AaS! 68: Do we live in a hologram?

What’s the idea behind the holographic principle? What does it have to do with black holes and the early universe? Does this…mean something?  I discuss these questions and more in today’s Ask a Spaceman!

Support the show: http://www.patreon.com/pmsutter
All episodes: http://www.AskASpaceman.com
Subscribe on iTunes: https://geo.itunes.apple.com/us/podcast/ask-a-spaceman!/id958825741

Follow on Twitter: http://www.twitter.com/PaulMattSutter
Like on Facebook: http://www.facebook.com/PaulMattSutter
Watch on YouTube: http://www.youtube.com/PaulMSutter

Go on an adventure: http://www.AstroTouring.com/

Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!

Big thanks to my top Patreon supporters this month: Justin G., Matthew K., Kevin O., Justin R., Chris C., Helge B., Tim R., Nick T., Branea I., Lars H., Timothy G., Ray S., John F., James L., Anilavadhanula, Mark R., David B., and Silvan W.!

Music by Jason Grady and Nick Bain. Thanks to WCBE Radio for hosting the recording session, Greg Mobius for producing, and Cathy Rinella for editing.

Hosted by Paul M. Sutter, astrophysicist at The Ohio State University, Chief Scientist at COSI Science Center, and the one and only Agent to the Stars (http://www.pmsutter.com).

EPISODE TRANSCRIPTION (AUTO-GENERATED)

You know what time it is. It's time for Ask a Spaceman. I'm your host, Paul Sutter. You've got questions and I've got answers. You know how this show works, but let's compress it one more time. You go online to Twitter or Facebook. Use the hashtag Ask a Spaceman. You can also follow me directly on Twitter and Facebook. My name is at Paul Matt Sutter. You can also visit the website, AskASpaceman.com. You can also email AskASpaceman at gmail.com. You can also go to YouTube.com slash Paul M. Sutter. And I'm out of breath. So many ways to ask questions. Get those questions to me. Keep in common. I love all the questions because that means I can keep doing this show, answering them. It is so much fun. You have no idea. We have a simple goal with this show, complete knowledge of time and space. And on the road to complete knowledge of time and space, we have today's questions. We have Liberty on Twitter asking, how about making a podcast on the hologram theory next time? Well, it won't be next time.

I don't know when you posted this. I'm pretty sure it was a long time ago. We also have Andrew B. on email asking, what is the holographic principle? Very, very cool set of questions. I want you to take a bite of something. I don't care if you have any food around you. If there's someone sitting next to you on the bus or the train or the car or whatever, just reach over and take a bite of whatever they're eating. When you take a bite of something, your mass grows. When your mass grows, your volume grows. When your volume grows, your surface area grows. All in proportion to each other. Imagine eating the smallest possible morsel of food. One atom. You are going to pop into your mouth a single atom and swallow it. Your volume will grow by the volume of that one atom. Your surface area will also grow, but not as quickly. You don't get the entire surface area of that atom added to the surface area of your body, only a small portion of that. But you're not a black hole, are you? I hope not.

If you were a black hole, if you were to eat something, your mass, your volume, your surface area would all grow, but there's a crucial difference. When a black hole eats something, its surface area grows faster than you might expect. Let's say a black hole consumes one bit of information. What does information mean? Why am I using that word? Well, all atoms, all particles, all whatever, carry with them certain facts. Their position, their velocity, their spin state, their mass, their charge, et cetera, et cetera, et cetera. You can actually load up a lot of information in one particle. So when you consume an atom, you're consuming a tremendous amount of information. If you consume a single particle, you're still consuming a lot of information. What's the smallest amount of information a black hole can consume? Well, how about one photon, one bit of light with wavelength equal to the width of the black hole? Let's define that to be a single bit of information. That's the smallest thing that a black hole can consume.

And something interesting happens. When a black hole eats one bit of information, its surface area grows by the plank length squared. Planck length? Lots of jargon here. You know what the Planck constant is, right? It's the quantum constant. It relates how much energy a photon of a given wavelength has. It kind of sets the scale for the quantum mechanical world. It is the constant, named after the scientist Max Planck, who figured it out, that led us all into the entire quantum mechanical world. That's a whole other show, so feel free to ask about Planck's constant and its meaning. You can combine Planck's constant, which is a particular number, with other constants like the speed of light, like Newton's gravitational constant, like the Boltzmann constant, like the permittivity of freezes. There's lots of constants floating around in the universe, all right? You can combine them to get other useful numbers, and these useful numbers might have length, or volume, or mass, and they give us some guideposts about where the quantum mechanical party starts getting interesting.

The Planck length is one such number. It's equal to 1.6 times 10 to the minus 35 meters, which is small, I guess. I don't really have any useful metaphors here for you. It's just an incredibly tiny number. The Planck length is very important for our understanding, especially of quantum gravity. When you get to small scales, say subatomic scales, that's when quantum mechanics takes over from classical mechanics. And if you get to really, really, really small scales, like around the Planck length, That's where our concepts of space-time start to break down. That's where quantum gravity starts to become important, and we don't really have a theory of quantum gravity. So things are a bit hazy at scales below the Planck length, below 10 to the minus 35 meters. that's very, very small compared to things like the proton or an atom. So we can do lots of quantum mechanics at these scales without having to worry about what's going on at smaller stuff, but that is the signpost. So if you square that, if you draw a little box, a little square, that's one Planck length on one side and another Planck length on another side, that's like a Planck area.

It's like a fundamental quantum unit of area. And isn't it interesting? then when a black hole eats one bit of information, its surface area grows by this very precise amount. Its volume doesn't grow by the plank length cubed like you would expect. When black holes consume information, their area grows in a very specific way. So the information going into a black hole is related directly to its surface, not its volume. Hmm. It suggests it suggests I'm using that strong word suggests that the action of a black hole happens on its surface, not in its interior. It's like instead of eating things and you consuming them and then going inside your body, it's like you just tape them to your stomach and call it a day. That's a very, very different picture of eating than we're used to. It's not about volume growing. The volume does grow, but not in the way you expect. It's more about the surface area growing. And this is the core of what we call the holographic principle. The holographic principle, or a hologram, is when you can represent all the physics, all the information, all the guts of a full three-dimensional object on just its two-dimensional surface.

Imagine. If by looking at someone's skin, you could learn everything you needed to know about their organs, their blood type, what they had for breakfast, what they're thinking right now. It would be really, really, really gross. And so I'm very thankful that is not the world we live in. But imagine if you could just look at the two-dimensional surface of someone's skin, you could capture all the three-dimensional information. Just how weird is that if all the information contained in a living, breathing, three-dimensional person is mapped onto the two-dimensional surface of their skin? Another example is holograms. Usually when you take a picture, which is two dimensions, of a particular scene, which is three dimensions, you lose some information. If I were to take a picture of you and then look at that picture later, I wouldn't know what the back of your head looks like. Because I didn't take a picture of that. I lost information from that mapping from three dimensions to two dimensions.

But holograms are designed to preserve that info. A two-dimensional image that lets you see all three dimensions. That is the definition of a hologram. In general, and mathematics likes to be general, anytime you can preserve information in a lower-dimensional context... For example, from going from three dimensions to two dimensions, which is hopefully obviously important for physics, that is a hologram. That is the holographic principle at work. This technique of preserving three-dimensional information in a two-dimensional context might apply to black holes. We haven't fully worked out all the consequences. It might also solve something else we know as the black hole information paradox, but that's another episode, so feel free to ask about that. So that's nice. Whatever. Black hole might be completely described by its surface. What does that have to do with anything that we might care about? Well, black holes are regions of intense gravity. Strong enough... that we have to care about quantum effects and that's why we don't fully understand black holes because they live at the intersection between quantum mechanics and gravity.

We don't have a quantum theory of gravity so we can't fully describe black holes yet. Lots of interesting stuff happening on the surface of black hole at that event horizon. And a lot of interesting stuff happening at the center, the region we call the singularity. The point of infinite density that isn't really infinite, but the only tool we have of understanding the center of a black hole is general relativity. General relativity says it's infinite, but we know that's wrong. Singularity doesn't really exist, must be replaced by something else once we figure all that junk out. Black holes contain singularities. Where else does a singularity occur? Bingo, the Big Bang. The earliest, earliest, earliest moments of the universe was hot and dense and exotic. At some point, the universe was so small, so hot, so dense that quantum gravity took over. And we don't fully understand that earliest moments because we, like I said, we don't have a quantum theory of gravity. It's hard to make progress in understanding the very early, less than a fraction of a second universe.

So what can we do? Can holograms save us? It's now time to introduce the most jumbled, nonsensical six letters that you're likely to encounter in your entire life. ADSCFT. ADSCFT. It's not a labor union. It's not a secret spy plane. It's not word scramble. It's, and I'll try to say this with all due respect, the only interesting thing to come out of strength. String Theory is another episode, so of course, ask. Generally, I'm not the biggest fan of String Theory, and I'd love to get into it in more detail, but... The main reason is it's beautiful, it's elegant, it's mathematical, it's blah, blah, blah, blah, blah. It also doesn't do anything. It's a blueprint for a hammer, not a hammer itself. Or it's a sketch of what might be a blueprint for a hammer, not the hammer itself. So I can't use it to go around explaining the universe. It doesn't have any utility. It can be the most elegant and beautiful mathematical structure known in the history of civilization. But if I can't use it to explain real observable phenomena in the universe, it's just that.

And I love mathematicians. No disparaging mathematicians here. But mathematicians masquerading as physicists is where I start to draw the line. But again, that's another episode. I don't want to get myself worked up too much about that. The mathematics of string theory is hard, and nobody can make any real progress in solving it. That's the key issue. We've been trying for decades, and we can't make progress in solving these problems that crop up in string theory, except maybe through ADS-CFT. ADS-CFT. Burn it into your brain. It's an application of the holographic principle, and it stands for, are you ready for this? ADS stands for anti-de Sitter. CFT stands for conformal field theory. This is gonna take a while to unpack. First, I'll do the CFT first, conformal field theory. Field theories are our language for quantum mechanics. Quantum field theories is how we describe the electromagnetic force, the weak nuclear force, the strong nuclear force, in a properly quantum mechanical way. I've done episodes describing field theories in the past.

I encourage you to look those up, pull them up, where I go into all the glorious and gory details of field theories. They're just a language for describing physics that we know and love. Conformal ones are... I don't know. They're special. They behave nicely. The mathematics are especially able amenable to easy calculations. Let's put it that way. Anti-de Sitter is a particular solution to general relativity. Named after one of the early researchers in general relativity, De Sitter. In this, he described one particular solution as this is the opposite of that solution, hence Anti-de Sitter. Anti-de Sitter, a particular solution to general relativity, it describes an empty universe. completely devoid of anything, with negative spatial curvature. Negative spatial curvature means that parallel lines eventually separate on very, very large scales. Empty universe, negative curvature, anti-de Sitter solution. It's a particular space time. In the late 1990s, it was discovered that there are some interesting connections between anti-de Sitter space times and conformal field theories.

Of all things, who would have guessed? There's a correspondence. There's a connection. Specifically. Anti-de Sitter spacetimes, like any spacetime, has a surface. It has a boundary. And if you're trying to solve a super hard problem inside that boundary, inside the volume of the space described by anti-de Sitter mathematics, I don't know, maybe you're trying to solve quantum gravity with string theory. Just tossing that one out there. It turns out you can map all of the information contained in the volume of an antedecider spacetime onto its surface. So you can make that holographic projection from three dimensions to two. You map everything out onto surface. You take everything contained in that universe, splat it out onto its boundary, and just look at the boundary itself. And the nature of the problem changes. That super hard problem that you're trying to solve inside The volume of that space-time, like quantum gravity with string theory, transforms. It changes character. It changes nature into a conformal field theory on the surface.

We don't have the tools. We don't have the expertise to solve string theory problems. But we do know how to solve conformal field theory problems. We do it all the time in quantum mechanics. It's our bread and butter. We've been doing it for decades. So by mapping, by making this holographic mapping from three dimensions to two in this very special space-time, we can transform the nature of our problems from unsolvable to kind of solvable. I know this topic is a jargon minefield. It's a one-way trip to jargon town, and you're going to go. So why don't we take a little break and contribute to Patreon. Patreon.com slash PMSutter is how you support this show. I can't emphasize it enough. It is your incredibly generous contributions that keep this show alive. Patreon.com slash PMSutter. As little as a dollar a month is all it takes to keep this show going. And I can't thank you enough for your extreme generosity. Now that you've gone to Patreon.com slash PMSutter, you've made your monthly contribution.

Now you can come back to the show. ADSCFT, Anti-Desider Conformal Field Theory, is a pretty big deal. It's also incredibly technical, as you might guess, because, like, everything in string theory is incredibly technical. It hasn't. I need to emphasize, it hasn't solved string theory. It hasn't solved quantum gravity. It's maybe, maybe an important clue that there might be routes to a solution using this technique someday, maybe. Perhaps. Kind of. Sort of. If we're lucky. Here's the upshot. Here's the super high-level summary. There are some problems that are so hard in three dimensions that we basically don't know how to solve them. We don't even know if solutions exist. We don't have the right tools. So instead, we'll map everything to a two-dimensional surface. The problem changes character. to a form where we do have the tools so we can solve the problem there on the boundary, on the two-dimensional surface, then translate the solution back into the three-dimensional world to make progress.

It might work with gravity. Solving quantum gravity in three dimensions is hard and possibly impossible. So instead, let's map the problem to two dimensions. In two dimensions, gravity disappears. The gravity that we're trying to solve completely disappears. It's replaced with a bunch of field theories. So solve the problem there where gravity doesn't even exist on the boundary. The mathematics have changed so much that gravity just drops out. It's replaced with a bunch of field theories where we know that we have the tools to solve. So solve it there, map the solution back to three dimensions, and voila! You have a route to understand quantum gravity without ever solving quantum gravity. It's a shortcut. It's a dirty secret to getting around this horrible, horrible problem. While this works and has been shown to work in a few limited cases, we don't yet have a working correspondence to our real-life universe. Our universe, for instance, is not described by an anti-de Sitter spacetime.

For one, it's not empty. It's full of matter. It's full of radiation. It's full of dark energy. For two, it doesn't have negative curvature. It has zero curvature. We live in a flat universe. So the anti-de Sitter space-time provides the special trick that allows us to flip back and forth to make that mapping possible with the holographic principle. That does not apply to our real universe. We do not live in an anti-de Sitter universe. We live in a different kind of universe. And our universe is evolving with time. Our boundary of our universe is constantly evolving. It's constantly expanding. So all the known correspondences between anti-de Sitter spacetimes and conformal field theories aren't as neat and tidy as you might think. And the field theory is on the opposite side of the coin. So you've made this great transition. You've eliminated gravity from your equations. Now you just have to solve a bunch of field theory problems on your boundary. But guess what? Sometimes those field theory problems are super hard.

Just because you can solve them in principle doesn't mean you can solve them in practice. If they're very strongly coupled, if they're very difficult to navigate, you've just swapped out one problem for another. You've just gone from the frying pan right into the fire. And maybe you haven't made any progress at all. So it's an improvement from string theory, which looks impossible, and we've been trying for decades and haven't really gone anywhere, to a problem that's merely insanely difficult, which I guess you gotta take it when you can get it. Man, if you can make any progress at all, you gotta celebrate, and this is considered progress. And I use the example of the black hole to show this holographic principle at work. That's why there's so much interest in black holes, because it might give us a clue of how this correspondence happens, of how we can utilize holographic principles to make progress on this very, very difficult problem of quantum gravity. But let's say, let's say we do it.

Fast forward 10 years, 20 years, 1,000 years, however long it will take. Let's say we're able to find a correspondence where we can map our full, complex, rich, interesting three-dimensional universe to its boundary. And I'm using air quotes here on the word boundary. Our universe doesn't have like a physical boundary, but we do have a limit to what we can see. It's called the horizon. So that will do the trick for our purposes here in the mathematics. We can map our realistic, our real three-dimensional universe to its two-dimensional horizon, its quote-unquote surface or boundary. Let's say the mathematics transform so much that gravity disappears on that boundary, that you can make some solution there, make progress in the field theories, map it back with your solution, and make predictions for how the universe ought to evolve and behave. You know, do problems in quantum gravity. Does that mean we live in a hologram? Does that mean our three-dimensional universe is a mirage? That really life and everything you know and love is taking place on a two-dimensional surface? And it just seems like the universe is three dimensions? I've seen some theorists actually say things along these lines.

And I don't think it's accurate. It's a mathematical trick. It's a way to map a very complex problem to a domain where the solution is easier to obtain. Then you obtain the solution, then you map back so you can make predictions. We use mappings all the time in physics. We do it in mathematics, mathematical physics. When we're trying to solve problems, we get a set of equations and say, man, that's really hard. We can apply some transformations to it to make the problem actually solvable. And then when it's solved in that domain, we translate it back to the original situation that we were trying to get at all along. We do it all the time, but we don't claim that the mappings are reality. We don't claim that this is, oh, this is really the way the universe works, is in this mapped space. No, we just acknowledge it as a mathematical trick and move on with our lives. So I personally have a lot of trouble swallowing the concept that just because you can make solving gravity easier using the holographic principle doesn't mean that everything is a hologram.

Just because you can make this mapping happen, and by the way, we can't make it happen. This technique has not solved any problems that are applicable to the real universe, but I'll give them the benefit of the doubt. Let's say we can someday make that happen, that we can understand quantum gravity using this holographic technique. It doesn't mean the technique represents the real physical universe. Just because you can find a solution through one route doesn't mean that route is reality. Of course, that leads down to a huge rabbit hole of what is real. Are electrons even real? Because electrons, we just have a set of observed phenomena and we have a model that best explains that observed phenomena. So doesn't electron exist? And I'm thinking that's another show. I'm thinking that's another show. But I'm feeling pretty strong about the holographic principle that we do not really, quote unquote, live in a hologram, that our universe isn't really two dimensional in our three dimensions is just an illusion.

It's a way, a potential, a potential. But it's the best shot we have right now of solving quantum gravity. It doesn't mean that's what reality really is. Thank you so much to Libra T and Andrew B for asking the questions that led to today's episode. Go to astrotouring.com, by the way, before you go, after you've done the Patreon thing, go to astrotouring.com and sign up for a trip with me and Fraser. It's going to be so much fun. I'm really looking forward to it. And also, spaceradioshow.com. Space Radio is live. It's going. We're recording shows every single week. You can call in and talk to me on the recording. Go to spaceradioshow.com. for instructions for all the episodes. Thank you to my top Patreon contributors this month, Justin G, Matthew K, Kevin O, Justin R, Chrissy, and Helga B. It is your contributions and everybody's contributions that keep this show going. That's patreon.com slash pmsutter. Keep those questions coming. Just get out there and do it, and I'll see you next time for more Complete Knowledge of Time and Space.

AaS! 67: Why can't I be an astrophysicist?

Why is it tough to become a scientific researcher? What are some of the barriers in the field? Are there any other options? I have a PhD - now what? I discuss these questions and more in today’s Ask a Spaceman!

Support the show: http://www.patreon.com/pmsutter
All episodes: http://www.AskASpaceman.com

Follow on Twitter: http://www.twitter.com/PaulMattSutter
Like on Facebook: http://www.facebook.com/PaulMattSutter
Watch on YouTube: http://www.youtube.com/PaulMSutter

Go on an adventure: http://www.AstroTouring.com/

Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!

Big thanks to my top Patreon supporters this month: Justin G., Matthew K., Kevin O., Justin R., Chris C., Helge B., Tim R., Nick T., Branea I., Lars H., Timothy G., Ray S., John F., James L., Anilavadhanula, Mark R., David B., and Silvan W.!

Music by Jason Grady and Nick Bain. Thanks to WCBE Radio for hosting the recording session, Greg Mobius for producing, and Cathy Rinella for editing.

Hosted by Paul M. Sutter, astrophysicist at The Ohio State University, Chief Scientist at COSI Science Center, and the one and only Agent to the Stars (http://www.pmsutter.com).

     

      Tweet #AskASpaceman

EPISODE TRANSCRIPTION (AUTO-GENERATED)

You know what time it is. It's time for Ask a Spaceman. I'm your host, Paul Sutter. You've got questions and I've got answers. You know how the show works, but let's keep trying until we give up. You go online to Twitter or Facebook. Use the hashtag Ask a Spaceman. Send questions my way and I will send answers your way. How easy is that? You can also follow me directly on Twitter and Facebook. My name is at Paul Matt Sutter. You can also check out the website, AskASpaceman.com. We have show notes. We have archive of episodes. every single episode ever produced. You can also follow me on YouTube. That's youtube.com slash Paul M. Sutter. Send questions there. And there's all sorts of zany, wacky science videos available for your enjoyment on that show. We have one simple goal with this show, complete knowledge of time and space. And on the road to complete knowledge of time and space, I'm going to return to a set of questions that I talked about a month ago. This is at 92 Rufino on Twitter asking, what does it take to be an astrophysicist? Vicky K via email asking, what kinds of non-academic jobs are available in astronomy and physics? And how do I become a space woman and or space man? And the reason I'm returning to this topic is I think in the last episode that I did on this, I was able to flesh out what a career in physics or astronomy looks like.

But I didn't quite get to answering the question. So now I really want to dig in to those questions of what kind of jobs are non-academic jobs are available. And was it take to be an astrophysicist? And then what I want to extend those questions because I want to explore really some challenges that exist in the current state of the field. So. Previously on Ask a Spaceman. I talked about how you needed certain skills in order to become an astrophysicist, but not necessarily the skills you might think. It's more about grit and determination and curiosity and passion and appetite for learning and openness to critique and willingness to communicate than the skills you might traditionally or perhaps naively associate with a career in physics or astronomy. And that the knowledge of science, the raw stuff you need to learn, and the ability to use math are a part of your scientific training. That's the first part of your career is to learn the body of knowledge to make you an expert and to give you the ability to use mathematics, to wield mathematics like a sword against the villain of science.

Ignorance? I'm not sure where I was going to take that metaphor, but we'll go with it. You learn those skills in school and especially on the job. For example, you may barely know how to use a hammer, but I bet after 10 years of carpentry, you'll know how to use a hammer. You may not know how to play the oboe, but 10 years of determination and grit and willingness to learn and openness to critique... you'll learn how to play an oboe. You may not be the best oboe player in the world, but you'll know how to play an oboe. The career process for a physicist is pretty straightforward. Also for an astronomer, undergrad, grad school, postdoc, and then a faculty or research position. But I ended the last episode on this topic on a cliffhanger. There are no jobs. Dun, dun, dun! Before I get there, what are the jobs? I don't want to say there's zero jobs. There are some jobs available to someone who has a PhD in physics or astronomy. There just aren't a lot. So what are those jobs? Well, of course, there's the professor at a major research university.

What you typically associate with the word scientist, someone in an office with piles of books and handwritten notes and a chalkboard full of equations and diagrams. And maybe they're a bad teacher or maybe they're really inspiring teacher, but that like, that's like the vision you have the stereotypical vision. What does a professor do? Well, not a ton of research. at least personally. A professor spends a lot of time teaching. They have a required teaching load. They do a lot of administration and departmental service, like they'll serve on committees for picking undergraduate students or mentoring grad students or organizing postdoctoral affairs, et cetera, et cetera. They do a lot of service. A lot of the work done in a department organizationally is done by the faculty themselves. They'll spend a big chunk of time writing grants, writing grant proposals, trying to get that juicy, juicy grant money. They will mentor undergrad and graduate students. They will manage the team of postdocs.

A high-level researcher at a major research university. isn't necessarily a personal research, they will still engage in personal research, you know, they'll they'll write up some codes, they'll be drafting some papers, but they're more like a research boss. They're more like a research manager, they have a team. of people, of undergrads, grad students, postdocs, associated faculty that are working with them. And that role, that level of your career when you're a full tenured professor, it's more like managing that team to make a productive research life for everyone involved rather than you down in the trenches doing the dirty work yourself. I'm not saying professors don't do it. And there is, of course, a continuum. Some professors are more lone wolves. and do a lot of solo research, and some are managing teams of over 100 people in their labs. So there's, of course, there's a spectrum, but I'm trying to give you a picture. Typically, a research professor will have a guaranteed income at least nine months out of the year, and that's tied to the teaching and service.

They use the grants to pay for student assistance, to pay for postdocs, to pay for gear, for pencils, for summer salaries. Sometimes they can buy themselves out of a teaching obligation with grant money. So that's a professor at a research University. There's also many teaching universities and smaller say liberal arts colleges and they will hire PhDs in astronomy and physics. It's basically the same thing that I just said, but the balance between research and teaching is of course shifted to teaching. So you'll have a bigger workload. You'll have typically smaller grants to work with, less flexibility to hire big teams. You can still have a productive research career, of course, but a large chunk of your time is going to be devoted to teaching. Outside of the universities for physics and astronomy, there's also a bunch of national labs. These are primarily run by the Department of Energy. These will be Los Alamos Lab or Oak Ridge Lab or Argonne or Livermore. Dotted across the country, these lab positions are a mix of your own research, whatever your own personally interested in, and assigned projects.

So research projects that support the particular mission of the lab. Your income in these positions is not typically guaranteed. They're what's called soft money positions. It means that the funding has to keep flowing, either from the lab budget itself, like the lab budget will have a chunk of money devoted to it, assigned by Congress, given to the labs to portion out how they see fit to serve their missions, and you might get a slice of that. You can also go off and pursue external grants from the National Science Foundation, from NASA, or from whatever, and that will pay your salary. If you can't get any external grants, then you might be assigned 100% of your time to internal projects that are not of your choosing. And if your specialty isn't required anymore by those internal grants, then you won't remain competitive. And goodbye. That's it. No money for you. Sorry. Figure out something else to do with your life. So while they're nice jobs because you don't have to do a lot of teaching and you don't have to do a lot of administration, it's tricky.

Year to year, you never quite know where your paycheck is going to come from. There are other positions at universities and labs, typically with a title like research scientist. This is like a super postdoc. You're working for one particular research group. Again, you're dependent on funding for that research group. So maybe it's a huge collaboration, like one of these satellite-based missions, like Hubble or WFIRST or JWST. And your research is specifically tied to that mission. You play some important role with that mission. Again, in those large research groups, those large collaborations, there's various infrastructure jobs like running observatories, doing data science, doing computer engineering and computer science in support of those large projects. Sometimes they'll hire people with outside expertise, like they'll hire a real computer scientist. And sometimes they'll hire a PhD in physics or astronomy who happens to be very strong or happens to be an expert in one of those engineering focused fields and they hire them.

So like the Planck satellite or the large synoptic survey telescope or the dark energy survey or the square kilometer array. These are giant multi hundred dollar instruments, sometimes billion dollar instruments. And there's a lot of jobs to support one of those missions. There are jobs literally all over the world. You can get jobs in the United States, in Europe, China, the rest of Asia. You can get jobs in South Africa. You can get jobs in India, in Australia, in New Zealand. There are openings all over the world. The universal language of physics is broken English. So it sounds like a lot. And to be true, kind of gave a little bit of a clickbait headline. Sorry about that. There are a lot of jobs. But there are a lot more PhDs produced every year. Way more than the number of available jobs. And to be totally honest, I have a really hard time recommending kids going into the field, which breaks my heart because I love giving talks. I love speaking to kids. I love speaking to the next generation, finding out what they're curious about.

And every once in a while, well, not every once in a while, basically every talk, at least one kid will come up to me and say, I want to be an astronomer. I want to be a physicist. I want to be an astrophysicist. I want to do what you do. And of course I tell the kid, you know, chase your dreams, junior. But deep in my heart, I'm thinking, oh, There's a really good chance that you're not going to make it. There's a really good chance that just based on the numbers, the statistics involved, there is no long-term position for you. I don't have firm numbers in front of me, but there's about 10 PhDs produced in physics and astronomy for every one open position. Every year, a certain number of positions open up from people retiring, funding streams coming online, grants being available. But for every one open position that is created, there's about 10 people who are qualified to take that position. But that sink in assuming all PhDs want a career doing research. That's about a 90% dream crushing rate, which is pretty abysmal.

We are producing way too many young scientists that can not just based on the funding, based on the raw numbers, cannot have a long-term future in science. And that's a tough pill to swallow. The hiring for these jobs typically happens all at once. Jobs are announced late summer, early fall, all across the world. Everybody submits. The deadlines are usually December, January, and then the selections start and they're filled by April for a start in the next academic year. So basically all of astronomy and physics grinds to a halt every fall. Every fall from October to December, not a lot of science gets done because on the student side, on the young career side, the students, grad students, and postdocs, they're busy filling out applications. And they're not just filling out one, they're filling out a few dozen applications. And on the senior researcher side, they're writing letters of recommendation and they're reviewing applications. They're sorting through, you know, they put out a job call.

Here's 400 qualified candidates. and they have to review them very carefully. So not a lot of science gets done, and that happens every single year. There's a website that you can visit called the Astro Rumor Mill. This is a wiki, so community curated website. It is a list of all open postdoc and faculty positions. And since it's community curated, people will say, oh, I've been shortlisted. I'm in the list of top six. You know, they called me back. Oh, I got the job. I picked the job. So, you know, if you were hoping for that job, don't wait for a rejection letter. You can just read the rumor mill. Let that sink in. A single web page, one page on the Internet. That's not that long. can list every single job available in astronomy in the entire world. Imagine doing that. Imagine attempting that with, I don't know, accounting. What if there was an accounting rumor mill that listed every single open job in accounting? That would be a gigantic, unnavigable website. That's why other career websites like monster.com, I guess, I'm not sponsored by monster.com, but it was the first example I could think of, where you need jobs to sort by location and you can pick and choose and you can target selectively.

No, when it comes to astronomy and physics, here's a dump of every single open position. You're going to apply to basically every single one and maybe you'll get through. That page is total poison, by the way, for aspiring young scientists because you get to see very, very clearly who your competition is. And if they happen to get jobs and you don't, and you're trying to understand why, that can drive you insane. So I actually recommend to graduate students and younger postdocs that I work with or mentor not to bother with the rumor mill because it's just, it will drive you insane to read that page. And I mentioned the term postdoc before a few times. Let me explain that a bit and explain how there's been a cultural shift in the past few decades in the physics and astronomy community that led to this unfortunate situation where there's 10 PhDs produced for every open job. And it's very difficult to get a long-term position. When you get a PhD in physics or astronomy, you're not considered quite ready yet for a real job.

You need to prove yourself as an independent researcher. Maybe you've been nestling under the protective wings of your advisor all through grad school. And, you know, if we sunk a lot of money into you, gave you a faculty position, maybe it turns out you don't really have your stuff together and you're just not going to make it. You're not going to fly on your own. So we need a period of time where you can be separated from your advisor, separated from your graduate institution. Whole new group of people, maybe even a whole new line of research, and see if you can really prove yourself to be the independent scientist that you like to think you are. These positions are temporary. They're called postdoctoral research positions, or postdocs for short. They'll last two to five years. And... In the good old days, not that they're ever really a good old days, but back in the day, you would do a PhD, you get your PhD, you would compete for an open postdoc position, someone else's research group, and you do maybe one, and then you'd apply for faculty positions, and that'd be it.

And then you'd have a job. And it's not like back then there were tons and tons of research positions. We haven't lost a lot of faculty positions in the past few decades. There's always been not a lot of jobs in astronomy. But in the past, there were fewer PhDs being produced and there were fewer postdoc positions. So as soon as you get out of grad school, you get your PhD, you're in your mid-20s, you apply for a postdoc, postdoc is incredibly competitive, very low success rate, If you don't make it, all right, that's life. You're in your mid-20s, you're fresh out of grad school, you have your PhD, you've got time to pivot, to move on with a different career. But if you do make it, if you do make it into that postdoc, there's pretty much a one-to-one match in the pipeline. If you make it to the postdoc phase, if you make it to that temporary research position, then most likely somewhere out there, somewhere in the world, There is an open, long-term research position for you, like faculty researcher at a university.

It may not be your top choice. There may be a higher teaching load or research load, depending on your interests. It may not be in the location you would prefer, but there most likely is a job available somewhere. Starting in the 1990s, there started to be a lot more graduate students. As universities themselves started to grow, there started to be a lot larger undergraduate populations than we've had in the past, which means a lot more people are gonna go into every field, including physics and astronomy, So you're going to get a lot more people with bachelor's degrees in physics and astronomy starting in the 90s. A fixed percentage of these are going to want to attempt a career in the sciences, a long-term research career. So they'll go on to grad school. And there's more money for grad school to support the undergraduate mission. Like if you have a bigger department with more undergrads, that's more tuition money assigned to your department. So you can hire more grad students and you need more grad students to do the teaching and the grading and all that kind of stuff.

So undergrad population started to grow. Graduate students population started to grow. But there were roughly the same number of open faculty positions. What we need, what we would love to see is just more money, more long-term funding. Like, oh, wow, there's lots more people attempting a career in physics or astronomy. Let's find the long-term funding so we can open up some more faculty lines so we can keep up with demand. But over the same time frame, over the 90s and over the 2000s, funding for science has generally been going down or at best flatlining. There's not enough money. floating around to open up new long-term research positions. It is, however, easier to get short-term funding. I want to do this research project, and this research project is going to take three to five years to complete, and I want to hire an assistant. I want to hire one postdoc for this one project based on this one grant so that they can do a lot of the work. That's much easier because it's a lot less money.

it's much easier to convince a funding agency to let me hire a postdoc than for a university to open up a new faculty position. So there's more undergraduate students, there's more graduate students, and now there's more postdoctoral positions. But there's still this cutoff. There's still relatively the same number of faculty positions. So we've come about, now we have a career path where instead of doing graduate school, one postdoc to really test your mettle, and then onto a faculty position, you might do two postdocs. You might do three. You might do four before you're considered even potentially for an open faculty position. Unless you're a ridiculous rock star, they won't even look at your application unless you've done two postdocs. So there's still a major cutoff. There's still, you know, just 50 years ago, 60 years ago, there were more PhDs produced than open positions. That's okay. But back then, the cutoff was when you were in your mid-20s. Now, since there's a lot more postdoc positions, you can generally get a postdoc position if you want one, and you can get another.

And then you try to compete for a faculty position, and sorry about your luck. So there's still the cutoff, but now you're in your mid-30s. There's still a cutoff, but it happens a decade later. So what does this do to people? If you want to pursue a career in science, in physics or astronomy especially, what if you want a family? What if you want kids? What if you want, I don't know, to own a house? That's going to be tough because you're going to live in one place for your undergrad. You're going to live somewhere else for five to seven years for grad school. You're going to live somewhere else for two to five years for a postdoc. You're going to live somewhere else for two to five years for a postdoc. And then you might have a slim chance of landing a faculty position. Maybe. What does that do to human lives? And you know what? If that sucks, well, it does suck. But if that's the way the system is, fine. But it's not exactly advertised that that's how the system is. It's not exactly communicated well to undergrads and grad students that, you know what? You may try to pursue this career for a couple decades and then not make the cut.

And a lot of it's based on random chance. You could be an absolute 100% rock star, the best person, the best scientist to come along in decades. But if your particular field of interest isn't fashionable, if not a lot of people are hiring, or if they just had a round of hiring, Let's say you know Supernova. Man, you have cracked the code of Supernova. You know how their interior structures work. It's going to be awesome. Your work is groundbreaking. But we just hired a Supernova person last year when you were in the middle of your postdoc and you missed the application window. Well, we filled that position. We don't need a second Supernova person. We're looking for someone else with another specialty. Sorry. That's it. These postdoc positions, I'm trying not to just gripe here, but the postdoc positions pay okay, but not the greatest, especially compared to peers who go out into industry. Some postdocs are so poor they can't even afford Patreon. Patreon.com slash PM Sutter is how you, yes, you are able to support this show.

All it takes is a few bucks every month and a bunch of you are doing it at the same time and that lets me pay for this show. That's what keeps the show on the air. I can't thank you enough for all of your generous support. You are the kindest, the most generous, the most supportive audience. An astrophysicist could ever ask for. I'm incredibly lucky and privileged to share my science with you. And I can't thank you enough for giving me the tools, the questions, and the financial support to make that happen. I don't take ads on this podcast. This is the only ad you're going to get. And that's patreon.com slash pmsutter. So there aren't a lot of jobs. Long-term science. What other jobs are available? Well, if you have an undergrad degree in astronomy or physics, you can do pretty much anything. If you have a PhD, you can do pretty much anything. A lot of PhDs end up going into finance, into consulting, into data analysis. They'll go to Silicon Valley. Think of not the research that you do in grad school or even undergrad, but think of the skills that you develop.

You come in with a lot of passion, a lot of grit and determination. So that's already valuable. And then you add to that over the course of your education, the skills you need to be a successful scientist. You get critical thinking. You get analysis. Rigorous analysis. You get mathematical skills. Those are highly prized skills in any industry. Every employer would love to have all their employees strong in critical thinking and analysis and communication and mathematics. It's such a well-rounded package. And you can demonstrate by the fact that you completed a gigantic dissertation in your PhD work that you can commit to long-term projects, that you really do have demonstrated grit, demonstrated determination. The unemployment rate for astronomers and physicists is essentially zero. I'm not making that up. It's not necessarily a job in research, but if you have a degree in astronomy or physics, you have a job somewhere if you want one. So that is the good news. That is the silver lining, that the skills you develop to become a long-term researcher, even if you don't actually become a long-term researcher, is at least incredibly valuable.

So what do you do? What do I have to say to that kid? Or if you're listening or you know someone who has a passion for astronomy or physics, I'm never going to tell you to not go for it. But I want you to know the state of the profession, which isn't talked about a lot internally. It's not in the brochure when you enter grad school. In fact, graduate school assumes, the entire structure of graduate school assumes you will eventually be a full-time researcher. They don't really talk about other options or prepare for other options, although that is slowly changing at the glacial academic pace. But I want you to know that those are the stakes, that there is a very low chance, even if you're incredibly talented, even if you're incredibly successful early career scientist, there is a very slim chance that you'll end up in a long-term faculty position. People who leave the field are spoken about like the recently deceased. Like, yeah, you remember Susan? Man, what a great researcher. She had such talent.

Man, she was going places. It's a shame. It's a real shame, man. That's how people talk about people who leave the field. Kind of ridiculous. So, one option for you, if you have a passion for physics and astronomy, is to go for it. Just roll the die, know that you're going to have to make some sacrifices and some very, very tough choices, but that's the state of the career. Or you can get a real human job with reasonable hours and solid pay. You can have a family and a house and all that good stuff. I don't know, just a suggestion. There are jobs available in the sphere of astronomy and physics. I mentioned those giant collaborations. They really do. They hire engineers. They hire data scientists and computer scientists. They hire graphic designers. They hire administrators. If you have a passion for physics and astronomy, but a talent somewhere else, you can still be within the orbit of the physics and astronomy worlds. You can help support the mission, and you will probably have a normal job And you can live a normal, happy, successful life with a good work-life balance.

That's another option. You can also volunteer in astronomy. And this is something that's really interesting that's been coming up over the past 10, 20 years. Historical astronomy especially has a great tradition of amateurs making huge advances in science. It's a bit harder now because, well, the problems we're facing are a bit harder. But this is where citizen science comes in. Things like Galaxy Zoo or CosmoQuest, where there are huge problems. that we don't have the computing horsepower or the computing techniques to solve that require a lot of human input, human intervention, human guidance, you can contribute to that. You won't necessarily get your name on a research paper, but I'm sure you'll get some credit somewhere and you'll at least have self-satisfaction that, hey, in my off time, I volunteered to some really cool research. That's a pretty cool thing to just be able to drop at a dinner party like, oh, yeah, you know, I helped discover a new kind of galaxy, you know, whatever.

Oh, no, no, no. I'm not a professional scientist. I do it as a hobby and I still made this major contribution. You can join a local astronomy clubs. You can get involved with astronomers without borders, dark sky initiatives, the international astronomical union. There's all sorts of great volunteer ways where you can take your passion for astronomy, but you can still have a job that pays you a ton of money. and gives you some stability, and where you can still explore the universe, share that passion with a community, and educate, discuss, communicate, spread the word, and spread the love of science while making your job somewhere else. So there's plenty of options out there if you have a passion. And I'm not gonna say don't go after the obvious thing, which is a research career, but it might be hard. Thankfully, There's a lot of room out there for all sorts of different talents and passions and energies and all sorts of ways to contribute to the scientific mission. Before I go, I do want to mention astrotouring.com.

The next trip is a cruise of the Caribbean where we're going to get nice and close and personal with the night sky and explore some mind ruins. It's going to be super fun. I'm doing it with Fraser Cain. Go to astrotouring.com. Rooms are booking fast. I'm not joking. So get your name in now. It doesn't take a lot of money to get your name on the list. And also, Spaceradioshow.com. Spaceradioshow is how I talk about the latest news. It's such a fun show. You can call and talk to me live on the air. It's Spaceradioshow.com. Big thanks to my top Patreon contributors this month, Justin G., Matthew K., Kevin O., Justin R., Chrissy, and Helga B., and all the other Patreon contributors that help keep this show on the air. That's patreon.com slash pmsutter. And thanks again to At92Rufino and Vicky K. for the questions that led to this episode. Such brilliant, brilliant, insightful questions. I can't thank you enough. And if you have time, if you can't donate to patron, that's totally cool. Can you do me a favor and go to iTunes and drop a review in, tell the world how much you love this show that helps bring other people in, which means more questions, which means I don't have to stop doing episodes.

Thank you. Everyone go to ask a spaceman.com for the website. You can also visit me, follow me directly on Twitter and Facebook. My name is at Paul, Matt Sutter. I'll see you next time for more complete knowledge of time and space.

AaS! 66: What in the world is metallic hydrogen?

What in the world is metallic hydrogen? What does it even mean? Where does it exist in nature, and can we make it in the lab? I discuss these questions and more in today’s Ask a Spaceman!

Support the show: http://www.patreon.com/pmsutter

All episodes: http://www.AskASpaceman.com

Follow on Twitter: http://www.twitter.com/PaulMattSutter

Like on Facebook: http://www.facebook.com/PaulMattSutter

Watch on YouTube: http://www.youtube.com/c/PaulMattSutter

Go on an adventure: http://www.AstroTouring.com/

Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!

Big thanks to my top Patreon supporters this month: Justin G., Matthew K., Kevin O., Justin R., Chris C., Helge B., Tim R., Nick T., Branea I., Lars H., Timothy G., Ray S., John F., James L., Anilavadhanula, Mark R., David B., and Silvan W.!

Music by Jason Grady and Nick Bain. Thanks to WCBE Radio for hosting the recording session, Greg Mobius for producing, and Cathy Rinella for editing.

Hosted by Paul M. Sutter, astrophysicist at The Ohio State University, Chief Scientist at COSI Science Center, and the one and only Agent to the Stars (http://www.pmsutter.com).

     

      Tweet #AskASpaceman

EPISODE TRANSCRIPTION (AUTO-GENERATED)

You know what time it is. It's time for Ask a Spaceman. I'm your host, Paul Sutter. You've got questions and I've got answers. You go online to Twitter or Facebook, use the hashtag AskASpaceman, and I will take those questions and I will answer them eventually. You can also email me at AskASpaceman at gmail.com or visit the website AskASpaceman.com, kind of convenient, or visit my YouTube channel, youtube.com slash PaulMSutter.com. You can ask questions all over the place. We have one simple goal with this show, complete knowledge of time and space. And on the road to complete knowledge of time and space, we have today's questions. We have Tom S. and at Abguntha via email and Twitter, respectively, asking about metallic hydrogen with several question marks after that. We have Andres Del C via YouTube. Could you please talk more about liquid metallic hydrogen? And we have Colin E via email. What's inside Jupiter and how did it get there? Metallic hydrogen. Okay, I need to take a few steps back.

Let's talk about phases of matter. Good old phases of matter. We're used to thinking of things very simply. Solid, liquid, gas. And transforming from one phase to another is very easy. Like take water. Take some solid water, aka ice, add some heat to it, add some temperature, increase its temperature, and it becomes a liquid. Then add some more heat and it becomes a gas. Okay, so that's pretty easy. If I want to take a material and change its phase from one thing to another, I just need to add heat or subtract heat. But pressure also gets to play in the phase changing game. So let's take room temperature water, which is a liquid, and stick it in a vacuum. Put it up in space. Put it in a vacuum jar and suck out all the air. What happens? It boils. It becomes a gas. So same exact temperature. Same exact room temperature water. Water that would be neither pleasant nor disgusting to drink. Just kind of meh. In a vacuum, it becomes a gas. And so we need to play both the heat game and the pressure game in order to change phases.

And we map this out using what we call phase diagrams. These phase diagrams say, okay, if I'm at this temperature and that pressure, I will have this state of matter. And every element or molecule or material gets its own unique phase diagram. So I'm Hydrogen will have a different one than hydrogen combined with oxygen to make water. And that will be completely different than oxygen by itself. And from carbon and lithium, everyone has its own phase diagram. Everyone has its own response. to temperature and pressure. And the phases in a diagram are like the countries, are like countries on a map, where there's boundary lines. And if you have this temperature and pressure combination, then you're within this boundary, you're within fluid land, and you obey the laws of the physics of fluids. But if you have another combination of temperature and pressure, you're in a different section of the map. You're in Gazistan. And you have to obey the ideal gas laws. And usually they're very strict boundaries where you can travel along this diagram just like you travel in a country and then you hit a border and you go through border control and then boom, you're in a new country with a new set of laws.

And that's what we see as changing faces. You're a liquid, you're a liquid, you're a liquid. Boom, you hit a border in temperature or in pressure and you keep adding heat or you keep adding pressure or keep removing heat, keep lowering the pressure or whatever. Then boom, you cross that border and now you're a gas. But there are some interesting places in these maps, in these phase diagrams. There are no man's lands. There are places that don't follow the usual rules of solid, of liquid, of gas. And it's usually when you go outside our normal everyday experience that these strange things happen to these materials. I think these strange things are properties of the materials themselves, but we only get to see these properties under extreme conditions. We don't normally see how water might behave or hydrogen might behave in this weird way until we really crank up the temperature, really lower the pressure. Then interesting things get to happen. It's like international waters. Like if you really crank up the temperature and pressure, these definitions of solid, of liquid, of gas get really, really fuzzy.

And if you're out in international waters, well, what rules apply to you? You're not really in any country. So who do you obey? How do you govern yourself? An example of this is what's called the critical point when it comes to water. There's a certain temperature and pressure that if you increase the temperature and increase the pressure beyond a certain point, water is no longer a liquid and it's no longer a gas and it's definitely not a solid. It's its own thing. It's its weird mix of liquid and gas properties. It kind of has some properties of gas and some properties of liquid, but But then some properties are missing, so it's its own thing. And if you only get there by cranking up the pressure and temperature past a certain point, what's called the critical point. Hydrogen has its own phase diagram. We usually don't get to experience almost all of that phase diagram. Under normal conditions here on the surface of the earth, with everyday temperatures and everyday pressures, it's almost always a gas.

If you find some hydrogen and it's by itself, it's a gas. It's just going to be a gas. You can heat it down to zero Celsius or heat it up to 100 Celsius. Nope, still a gas. Very low pressure, very high pressure, still a gas. If you cool it way down to 33 Kelvin, that's 33 degrees above absolute zero, it does become a liquid. And if you cool it down below 14 Kelvin, so anything less than 14 degrees above absolute zero, it becomes a solid. So you can make liquid heat hydrogen and you can make solid hydrogen. It just has to be really, really cold. But that's at typical normal everyday pressure. So if you keep the everyday earthly pressure, one atmosphere, say, and you lower the temperature, then you get to liquid and a solid. If you crank the pressure up, you can raise the temperature and you can actually get back a hydrogen solid. So there is solid hydrogen at high temperature, but that's only at very, very high pressure. And hydrogen has these particular properties because hydrogen doesn't like to be by itself.

Hydrogen is just a single proton with a single electron in a shell around it. That's it. That's all it takes to make a hydrogen atom. And a single proton with a single electron is like the most eligible bachelor or bachelorette in the elemental world. It'll just hook up with anybody. Doesn't care. Usually, it just pairs up with itself. So we usually get hydrogen as twins. Hydrogen, in our normal experience, is diatomic. It merges with itself. It combines with itself to make molecular hydrogen that is much more stable, much less reactive, just likes to hang out by itself or with itself because it's a twin. All right. And so when you encounter hydrogen gas, you're actually seeing diatomic hydrogen gas. Hydrogen molecules are paired up together. When you cool it down to make a liquid, that's diatomic hydrogen as a liquid. Freeze it so it's solid when you're below 14 Kelvin, and that's diatomic hydrogen frozen solid. But if we're devious enough, if we're crazy enough... We can split those bonds.

We can break diatomic hydrogen apart. And we can get monatomic hydrogen. All right, it sounded, it looked cooler when I wrote it down in my notes, and it didn't sound that great, but we're just going to roll with it. We can play some games where we can split that hydrogen apart. What does it take? It takes Patreon. Go to patreon.com slash pmsutter to learn how you can support the show and all the education outreach activities I do. There's way more details on the Patreon page itself. I can't thank you enough for all of your generous contributions for this show, but I'm going to try again. Thank you so much. That's patreon.com slash pmsutter. What does it really take to split hydrogen apart so we can see the bare elemental hydrogen? It takes incredible temperatures and or incredible pressures. And if you just take a hydrogen gas and you really heat it up and you keep the pressure low, you're going to get a plasma where the protons and the electrons separate from each other and you just get a thin, hot, soupy mix of protons and electrons.

Like the sun, the interior of the sun is this hot, soupy mix of protons and electrons. It's a plasma of hydrogen. What if... You increase the temperature and you increase the pressure. What if you did both? So you get a plasma, a fourth state of matter, if you increase the temperature but you let the pressure go. What if you have both high pressure and high temperature? Well, past a certain combination of temperature and pressure, the bonds between the paired hydrogen are forced apart and and you get individual hydrogen atoms, aka protons, and they float around. What do individual protons floating around look like? It looks like a liquid. But this is a very different kind of liquid than the cold temperature liquid hydrogen. That one at 33 Kelvin was still diatomic. It was still two hydrogens glued together, paired up, fluiding around, doing whatever a fluid does. This is a very different beast because the bonds have been broken. Because the hydrogen has been ripped apart, now it's just single protons and single electrons floating around.

That's going to behave differently than the low temperature version, we think. I'm saying we think because this is largely theoretical. I'll get to the experiments in a bit. You need, in order to make this happen, this weird state of hydrogen, you need at least one million times sea level air pressure and preferably, you know, three or four million times sea level air pressure. And you need at least around a thousand Kelvin to do the trick as well. We think hydrogen will behave this way because we understand the chemistry, because we understand electrostatic forces, because we understand quantum mechanics. We can predict that this is how hydrogen ought to behave at high temperature and high pressure. Let me talk about this some more before I get to the experiments. The best word I can use to describe the state of hydrogen at extreme pressures and extreme temperatures is weird. Not only are the protons separated from each other... because of the extreme pressures, but the electrons are forced out of their shells and they also float around.

So you get a soup of protons and electrons like the more familiar plasma, but with insane pressures. And it's so different from a plasma that we give it a new name. We call it metallic hydrogen. Why metallic? Well, think of a metal. How would you define a metal? Is it hard, shiny, a good electrical conductor, probably dense, doesn't have to be dense, but typically dense? Metals, and most elements, by the way, are metals, have these properties because the atoms or the molecules that make up the metal, they link up, they link together to form a lattice. So their electron shells overlap, right? They link together, and each atom will have a few electrons left over. So they'll use some electrons to form the bonds, the linkages between them, and then there'll be some electrons left over that just float around and just hang out. So you get a lattice, a structure of ions, that's the atoms that are linking up together, and then these are embedded in a sea of free-floating electrons. And it's these free-floating electrons that give the metal most of its properties.

That's what makes it shiny, that's what makes them good electrical conductors. And if you melt down a metal, you get a liquid metal. You can take gold and melt it down and it's still gold. It's just the liquid phase of gold. And it still has all the essential properties, except for being hard. But it has a lot of the essential properties. There's still these linkups of the gold ions. There's still free-floating electrons. So you can have liquid metals. The concept of a liquid metal isn't that crazy. And it's the properties of those free-floating electrons that make a metal a metal. So here we have hydrogen at high temperature and high pressure. And hey, look at that. The electrons are floating around. That's a metal. It's probably shiny. It's probably a good electrical conductor. It's probably pretty dense. That's not so bad. All right. Metallic hydrogen. It turns out if you take hydrogen and subject it to high temperatures and pressures, it forces apart the atomic bonds. It forces apart the electric bonds and you get a new soupy thing that kind of sort of looks like a metal.

It's not the only element that does this. There are things like carbon that when you subject it to high temperatures and high pressures may not normally be a metal will start acting like a metal. And so that's not really the crazy part. Here's the crazy part. A normal medal, like a bar of gold, that you can donate to patreon.com slash bmsutter. When you pick it up and say you squeeze that bar of gold, you pick up that bar of gold and you want to squeeze it. It resists you. All right. It's pretty tough. It doesn't like being squeezed. What is resisting you? Well, it's those it's those ions. It's the atoms and molecules that are all linked together that have formed this lattice. They don't like being squeezed any more than they already are. So they share electrons so they can link up. But that's as close as they're going to get. And so you can try squeezing on it, but you're pressing, you're trying to overcome the electrostatic bonds, the electrostatic repulsion between these ions. They just don't want to get any closer to you.

And it's just the electromagnetic force that's supporting that pressure where you try to squeeze, but it's going to say, nope. I've got electrostatic. I am literally repulsed by my neighbor, and I'm kind of linked up to them against my will, but here I am, and there's no way you're going to get me to squeeze any tighter. Metallic hydrogen does not do that. It's a liquid. It's a soup. It is also not going to want to be pressed together, but... There's no latticework. There's the free-floating electrons, which make it behave like a metal, but there's no latticework of ions because the ion of hydrogen is just a proton. It's just a single proton. It's got nothing left to give. It's not going to link up. It's not going to share electron shells in orbitals and blah, blah, blah to form a lattice. It's just a proton, folks. It's not going to make that latticework. So it's not electrostatic. It's not the electromagnetic force that's preventing you from squeezing metallic hydrogen tighter together.

Instead, it's degeneracy pressure. It's quantum mechanics, folks. It's the good stuff. degeneracy pressure, normally you only encounter it in discussions of, say, white dwarves or neutron stars. You can only put so many electrons in a box. Say you fill up a box with electrons. They have all the same charge, so they're going to repel. They're not going to want to get closer together. That's electrostatic repulsion. You can squeeze on them and make them get closer together. And you can do a pretty good job. So if you take a bar of gold, you can put it in anvil or whatever. You can squeeze it. You can make them get closer together whether they like it or not. You can overcome electrostatic repulsion. But then you'll hit a limit. You'll hit a limit because no two electrons can share what's called the same quantum state. They cannot be in the same place at the same time. They just can't. So even if you're able to overwhelm the electrostatic force, you're going to hit a wall, and that wall is degeneracy pressure.

Here's another way to think about it and why it's a quantum mechanical thing. And this way to think about it is from the Heisenberg uncertainty principle. If you take, say, a couple electrons and you squeeze them really close together, what are you doing? You're pinning down their position. You're saying, you're going to be right here, not over there. You're going to be right here, right between my fingers that are squeezing really, really, really, really tight. So that is reducing the uncertainty in the position. They can't escape. They're being squeezed down. But if in the Heisenberg uncertainty principle, if you reduce the uncertainty in position, you increase, you enhance the uncertainty in momentum. Momentum is velocity. So it's the more you try to squeeze two electrons together, the more they're going to vibrate. the more they're going to buzz. And that buzzing, that vibration, that momentum is like a pressure. You know, they're like, imagine trying to take two bees in a small metal box and you're making that box smaller and smaller and smaller.

You're saying, no bees, you're going to be right here in this tiny little box. But they're going to go nuts. They're going to go buzz, buzz, buzz, and they're going to bounce against the walls of that little container, especially as you're trying to make it smaller and smaller. And that will resist them. you trying to push it together that will resist you trying to make it smaller. That is a pressure. And that is degeneracy pressure. And that is a pure quantum mechanical thing. This isn't the electromagnetic force supporting liquid metallic hydrogen against further collapse. It's quantum mechanics. That's what makes metallic hydrogen weird. It's a liquid, it's a metal, and it's dominated by quantum mechanical forces. That's the secret sauce. That's the specialness in liquid metallic hydrogen. To make liquid metallic hydrogen, you need pressure and heat. You need them both. Where can you get? The sun is pretty hot and there's a lot of pressure, but there's also a raging nuclear fire in the core, so it's a little bit crazy there.

So it turns out the material in the sun, the hydrogen in the sun, just turns into a plasma. Earth's core is very hot. And it's under a lot of pressure, but there ain't a lot of hydrogen there. So good luck with that. What about the gas giants? Yeah, yeah, yeah, yeah. Jupiter and Saturn are gas giant planets full of hydrogen, also helium. So you have all the right ingredients in Jupiter and Saturn. You have hydrogen, which if you're going to make liquid metallic hydrogen, good to have some hydrogen on hand. You have hydrogen, you have high pressure because, you know, just, you know, go down under the cloud tops and the deeper you go, the more stuff is going to be on top of you. So that's naturally going to provide a lot of pressure. What's really going on inside of Jupiter? Well, we honestly don't fully know. I mean, we haven't stuck a lot of probes deep inside Jupiter, especially thousands of kilometers where we think things might start getting really interesting. We know the cloud tops.

We know surface activity. We know about the atmosphere just underneath it. That's from observations with different wavelengths of light that can penetrate the very topmost layers. But also by looking at the formation of storms and cloud patterns that put certain requirements on what's happening just underneath it. We can use the strength of the magnetic field around Jupiter to understand what's happening mixing up deep in its core. We can use variations in the gravity as we orbit spacecraft around it. And we can use simulations and computer modeling and compare with observations and figure out what's going on inside. Mostly... Jupiter is hydrogen with helium and a few other things. And getting that higher pressure, again, we don't know for sure what's happening inside Jupiter, but slowly over time, we're getting a better picture, especially with instruments like the Juno spacecraft, which is in orbit around Jupiter right now, unless you're listening to the show deep into the future, in which case Juno was a spacecraft that orbited Jupiter.

Higher pressure is easy. Just go deeper. There's more crushing weight of atmosphere on top of you. Eventually, actually, the hydrogen gas gives way to a diatomic hydrogen fluid that passes critical point. So it's not quite a fluid or a gas, just like water passes critical point, blah, blah, blah. So there's like a thin transparent layer of hydrogen fluid slash gas. And then you go even deeper. But you need the temperature too. And how do you get hot inside a gas giant? It turns out it's this really interesting mechanism called the Kelvin-Helmholtz mechanism. Not to be confused with the Kelvin-Helmholtz instability, which is another show. Feel free to ask about that. This is the Kelvin-Helmholtz mechanism. Check it out. You have a ball of gas. Could be a planet, whatever. It's a ball of gas. Its surface is exposed to space. So it's going to radiate heat because that's what things exposed to space do. It'll glow a little bit. Radiate heat. What does a gas that radiate heat does? It cools off.

What does a gas that cools off does? It compresses. It gets smaller. So... You have the outer layer of the planet cooling off, which is going to make it compress. That squeezes the core. What does the gas that gets squeezed do? Doesn't happen? Whatever. It heats up. The core heats up. That makes the surface hotter. What does the hot surface do? It radiates. What does that radiation do? It cools off the surface. What does the cooling surface do? It squeezes the core. What does the squeezing core do? It heats up. What does the heat do? It's a cycle. It's a mechanism. It keeps the interiors of giant planets warm. This is what prevented them. Otherwise, they would have cooled off a long time ago. But this act of radiating heat, compressing, can make the cores very, very hot. There's other possible mechanisms of heating the interior of Jupiter. You can have helium rain form and falls through the metallic hydrogen. Spoiler alert, there's metallic hydrogen in Jupiter. There's friction here and that can generate heat too.

We don't know what is the most important mechanism, but there's a couple. How did these elements get inside of Jupiter? They were born with it. Our solar system was three-quarters hydrogen, one-quarter helium, and a small percentage of other stuff. The pre-solar disk, that's what it was made of because that's what basically everything in the universe is made of. And the gas giants got to, and the sun, got to retain a memory. Here on Earth, we lost our hydrogen, we lost our helium, we just have the heavier stuff. But the outer planets past where it's too cold to obliterate by radiation any ices that might form, you get to retain a memory. You get to keep that image, kind of that window into the early solar system. And that's why studying Jupiter is so important. It is a window into the very early solar system. It's a picture of what our pre-solar disk looked like before we got here. But that's another show. So there, in the core, or in not quite the core, we think the core of Jupiter might be solid, but there is a very thick layer.

Most of the volume of Jupiter actually has the right conditions, the right temperatures, and the right pressures to make metallic hydrogen. Liquid metallic hydrogen. So most of Jupiter, we call it gas giant. Most of it is actually liquid. Most of it is actually liquid with an atmosphere, a gaseous atmosphere on top of it. You dive down deep enough, you will encounter this strange state of matter. That is a liquid. That is a metal. That is supported by quantum mechanical forces. How crazy is that? Usually you think of these weird quantum mechanical effects and you have to go to a white dwarf or a neutron star. No, you can just go in our backyard. Right there. Go in your backyard, look up, find Jupiter, find Saturn. You're looking at a giant ball of liquid metallic hydrogen. How awesome is that? That is significantly awesome. Before I go, I do want to talk about the experiments that have been done. We've been trying to make liquid metallic hydrogen in the lab, or at least some form of metallic hydrogen.

You can also have solid metallic hydrogen. Every few years, there's claims of making it in the laboratory, most recently at the end of 2016, using a diamond anvil, which is a great band name, by the way. Feel free to use that if you're trying to cook up a band name. Diamond anvil creates an enormous amount of pressure, which is what you need to make metallic hydrogen. They thought the latest experiment, the end of 2016, may have been a lock. In fact, in the abstract of the paper where they announced it, they said, yes, we totally made metallic hydrogen. It was disputed almost immediately. And the sample of metallic hydrogen survives. It turns out metallic hydrogen, for various reasons, is what's called metastable, which means if you make it and you don't bother it, it will actually hang around for a while. But apparently they bothered it and then it disappeared and they haven't been able to make it since. And so that is still up in the air of whether metallic hydrogen has been created in the laboratory.

Right now, the only place where we're pretty sure metallic hydrogen exists is in Jupiter and in Saturn. But we're not 100% sure. Remember, this is a theoretical state of matter based on our understanding of the laws of physics and our understanding of chemistry. Maybe wrong, probably not. There's probably liquid metallic hydrogen in Jupiter and Saturn. More measurements by the Juno probe and... What's left of the Cassini probe after it plunged into Saturn. The data we're still analyzing, trying to understand that, you know, what is the character of this very exotic, very strange and yet kind of normal. Hydrogen had this superpower in it the whole time. You just needed to subject it to extreme stress in order to bring it out like normal superpowers. Before I go, two quick announcements. Again, Space Radio is live where you can talk to me on the radio and ask me questions and I'll answer right away. Spaceradioshow.com. We record every Thursday at 4 p.m. Eastern. Call 888-581-0708 to talk to me.

And also astrotouring.com. Fraser Cain and I are at it again. We are going on a Caribbean cruise to experience some beautiful dark skies, to experience the Kennedy Space Center, to experience some mind ruins together. And we want to do it with you. Not you, you. Yes, you. astrotouring.com. Sign up, because it'll be fun. Thank you so much to my Patreon contributors, especially Justin G., Matthew K., Kevin O., Justin R., Chris C., and Helga B. It is your contributions that keep this show going and growing, and all my education and outreach activities. I'm eternally grateful. Thanks to Tom S. at Abguntha, Andres Del C, and Colin E. for the questions for today's episode. You can ask more questions by following me on Twitter and Facebook at Paul Matt Sutter using the hashtag Ask a Spaceman. Go into AskASpaceman.com. Go into YouTube.com slash Paul M. Sutter. Whatever you do, just get me questions, and I will see you next time for more Complete Knowledge of Time and Space.

AaS! 65: How does one become an astrophysicist?

How does one become an astrophysicist? What are the challenges and rewards of that kind of career? Are there even any jobs? I discuss these questions and more in today’s Ask a Spaceman!

Support the show: http://www.patreon.com/pmsutter

All episodes: http://www.AskASpaceman.com

Follow on Twitter: http://www.twitter.com/PaulMattSutter

Like on Facebook: http://www.facebook.com/PaulMattSutter

Watch on YouTube: http://www.youtube.com/c/PaulMattSutter

Go on an adventure: http://www.AstroTouring.com/

Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!

Big thanks to my top Patreon supporters this month: Justin G., Matthew K., Kevin O., Justin R., Chris C., Helge B., Tim R., Nick T., Branea I., Lars H., Timothy G., Ray S., John F., James L., Anilavadhanula, Mark R., David B., and Silvan W.!

Music by Jason Grady and Nick Bain. Thanks to WCBE Radio for hosting the recording session, Greg Mobius for producing, and Cathy Rinella for editing.

Hosted by Paul M. Sutter, astrophysicist at The Ohio State University, Chief Scientist at COSI Science Center, and the one and only Agent to the Stars (http://www.pmsutter.com).

     

      Tweet #AskASpaceman

EPISODE TRANSCRIPTION (AUTO-GENERATED)

you know what time it is it's time for ask a spaceman i'm your host paul sutter you've got questions and i've got answers you know how the show works but let's ask the question and get the answer again you go online to twitter or facebook use the hashtag ask a spaceman and Fire those questions away, and I will catch them. I will catch them with my space internet powers, and I will put them in a file, and then I will peruse the file, and I'll pick ones to answer on this show. It is that simple. You can also email me directly at askaspaceman at gmail.com or visit... Ask a spaceman.com. That's the website. There's all the show notes, links to all the episodes. You can start to see if I've already answered the question. Maybe before you ask, you know, all sorts of stuff. You also, you can also go to youtube.com slash Paul M Sutter, where there's all sorts. Thank you so much for watching. At 92 Rufino asked, what does it take to be an astrophysicist? And we have Vicky K via email asking, what kinds of non-academic jobs are available in astronomy or physics? And how do I become a spaceman and or space woman? excellent excellent question i get these questions a lot especially from kids so if you you it may be too late for you to become an astrophysicist you're already set in your career and you're already living a a healthy and happy and productive life uh but maybe you have kids or maybe you're maybe you're not quite at that stage where you're set in your career and you're wondering about physics and astronomy and usually when kids are asking me this question they typically tend to be middle schoolers and high schoolers and they're worried.

They're stressed out. We talk so much to middle schoolers and high schoolers about careers and options and setting your path in life that I think they tend to get stressed out. They're worried about making the right choices, about picking the right classes, about extracurricular that and club this and what do I need to do? What's the best choice for college, et cetera, et cetera. I get it. I get it. If you're young and you know what you want in life, you don't want to screw it up. You want to hit every right note to maximize your chances of having your dream job. So to ease those fears, so when I get those questions, I tell my own story. I tell my own story of how I became an astrophysicist, and I think that might ease some of the fears. Or if you have a youngster in your life that you know that is interested in a career in physics and astronomy, you know what? The path might be a little bit different than you expect. And the number one thing I say, and this is 100% true, I did not take a single physics class in high school.

I am not joking. My high school had two options. You could either take a track of physics and chemistry, or you could take a track of computer science. And I picked computer science. And I was one of like two kids that did it. But there we were taking computer science when everyone else was taking physics and chemistry. And I didn't take any physics, any chemistry in high school, which is interesting because I had always loved reading books about science. As a kid, I loved astronomy and dinosaurs. And as I got up in the middle school and high school, I liked more technical subjects. So I was reading books about astronomy and physics and history and biology and all that good stuff. And two books I remember in particular, one is Elegant Universe by Brian Greene and And the other is Godel Escher Bach by Douglas Hofstetter, both very influential books into my life, my upbringing, and my current mental state. And I did have a telescope that I barely knew how to use. I got it for my birthday when I was 12.

12 or something. And, you know, I could use I could I could look at the planets. I figured I was able to pick out some nebula and some globular clusters and things like that. But I didn't I didn't bust it out a lot. But thinking back, I really don't know. Why I didn't take the physics track. I was also a computer geek, to be fair. I do love computers and programming and all that kind of stuff. And so it was natural for me to pick computer science. And so I went into computer science in college. I wasn't even on a science track, a physical science track. And... I really don't know why. I never took an interest in it. I never thought it was for me. Maybe I just never realized that being a scientist was an actual job. It was just something that other people always did. Maybe there were feelings of inadequacy. They're like, there's no way I could do something like that. Like, oh, this person's figuring out string theory. This person's figuring out dark energy. There's no way I could do that.

I'll just have to sit in the back and program some computers. And computer science was nice. And if you're a computer scientist, I'm very happy for you. But it wasn't really fulfilling for me. The kinds of problems we were using to develop our skills just weren't very intellectually stimulating for me. And the third year of college, I took an elective in astronomy. And I still remember the teacher, Professor John Poling. And I barely remember the content of the class. It was an astronomy course for... Like engineering majors. So it's slightly more technical. There was a decent amount of math involved and some jargon. But it was an overview of astronomy. And something about the class just clicked. And I remember having conversations with Dr. Bolling. And in the first... three weeks of the class so this is like before we even had our first test i'm like well i'm really digging this like i had taken physics classes in my freshman year and sophomore year and they were just physics class i didn't really think much of it but it was in this astronomy class that something really was pulling at me and in three weeks into the semester no joke i woke up one morning and i this thought popped into my brain i just woke up and said i'm gonna be a physicist Boom.

Absolutely crystal clear thought. And by the end of the week, I'd switch majors and I had to drop half my classes because they were computer science classes and no longer applicable to my new newly declared major. I was going to be a physicist. I didn't know if I was going to be an astrophysicist or a high energy theorist or, you know, or a whatever. I just knew I wanted to push in this direction. This direction made more sense to me for reasons that I can't really describe yet. The very next semester, I regretted my decision because that's when I started taking the serious physics classes, the physics classes for physicists, the physics classes designed to make you question your life choices, right? that are deliberately hard. And it was just a course on classical mechanics, rotational motion, drag, fancier things like Hamiltonian formulation of mechanics. And it was really tough. I mean, there were tears. I'm honest enough to admit I cried during that class. It was rough going, but it was clicking.

It was fitting. It was tough, but I kind of liked it. I never got 100% comfortable with the mathematics in pretty much my entire career. I don't consider myself an exceptional mathematician. I at least had ceasefire agreements with the mathematics so we could make progress together. And I started taking more classes. The more classes I took, the more I enjoyed it. I started taking classes on special relativity and general relativity and thermodynamics, statistical mechanics, all the guts that goes into doing lab classes and recreating famous experiments. And I was having a really good time. It was mind-blowingly tough, but I liked it. And as my bachelor's in physics was approaching, I was approaching graduation. Now what? And I decided to aim for grad school. Why? To be a professor, to be a researcher. I don't know. It just seemed like a good idea at a time. I think the thoughts I was having was, I'm feeling good. I'm liking this. Let's see how far I can push. Then I get into grad school at the University of Illinois.

And... When you first show up for grad school, you know, you have to write some essays like, I've always wanted to be a physicist. And it's really special to me. And I'm really interested in insert research topic here because of this childhood experience there, blah, blah, blah. So I wrote some essay. I don't even remember. It was probably horrible. But I got in. It was good enough, I guess. I got in. I didn't have a focus. Like, is it going to be cosmology? Is it going to be astronomical surveys? Is it going to be particle physics? It took me a few months to decide. But eventually I settled on astrophysics and cosmology. I found a good advisor and we had a really good time. And when kids ask me how long I went to school, how long did you go to school to become an astrophysicist? The answer is 11 years. And they usually lose their junk. I mean, it's just of all the space facts I've related to them, nothing blows their minds more than telling them, yes, I went to school for 11 years after high school.

But I have to explain because that sounds like a big number. It is a big number. It's a good chunk of my life. It took me five years to get my bachelor's and then six more to get the Ph.D. But in graduate school, in that six years of graduate school, you're only in classes for about two years. And this changes school to school. You're only in classes for about two years. And then the rest is basically a job. You're a trainee under a mentor, your graduate advisor, who's guiding you through a research project and teaching you how to become an independent researcher. And that's much more like a job. Like, you know, here's the list of things we got to do. Let's let's get to it. And then you have weekly meetings with your boss and you have colleagues and you have reports to write all the usual stuff. So it's much more like a job than it is school. And that advisor relationship is key. You pick your advisor in the first or second year of grad school, and it's basically your science parent, your science mom, your science dad, for half a decade.

For five, six, in the experimental physics, this can go to seven or eight years. Theory tends to be a little bit shorter, more like four or five. And It's like so important that you get the bones of your education in your classes. You're going to learn the basics of physics that every physicist needs to know. But it's up to your mentor, your advisor, to bring you up to speed in the discipline you choose because you're not going to learn about the latest in astrophysics research forever. from a class because it's changing all the time. It's changing literally every single day. And so it's up to the advisor to bring you up to speed and show you how to make advances in the field, show you how to become a researcher, how to write papers, how to coordinate with collaborators, how to present at conferences, how to ask intelligent questions, all the guts that go into being a functional member of the academic community. So you have the bones in your classes and you get the guts from your advisor.

And that's where the magic happens. That's where you're transformed into a scientist. It's not in your classes. It's not by getting the bachelor's. It's not by your first couple years of graduate school. It's not the degree itself. It's not the PhD itself. That's like the certification. That's the stamp. The transformation to becoming a scientist happens under the guidance of your advisor. And the coolest thing to me, something that seriously blew my mind, is that your advisor doesn't know the answers. When you pick a problem to work on, Usually your advisor will have say, OK, you know, here's a few things that I'm interested in. You know, pick one of them. That's going to be your focus. That's going to be your specialty. So you work on this together. You pick your dissertation topic together. And it's an intersection of your advisor's interests and your own interests. And your advisor doesn't know what the result is going to be. I remember multiple times and the first time this happened, it really blew me away.

When I would develop some new method or get some preliminary result, you know, I'd be working for a couple of weeks and I did computational astrophysics for my PhD. I run some simulation. I get some result like, OK. And then, you know, I have my meeting with the advisor, Paul Ricker, by the way. At University of Illinois. And, you know, I had to figure it out on my own. And then we'd have the meeting. And then I would have to tell my advisor how I figured it out and what the implications might be. And he would start asking me questions like, well, how did you do this? Well, how do you figure this out? I'm like, wait a minute. Don't you know? Oh, no, he doesn't. Because this is brand new stuff. Nobody's done this before. And the two of us, first me, I'm the first one to ever do it. And then my advisor is the second person on the planet to know about this fact or this insight or this method. And that blew my mind because I thought my advisor was most likely the smartest human being in the world.

And I still think that might be true. And he was light years ahead of me in knowledge. But we were pushing on this problem together as partners, as co-workers, as colleagues. And it was a very, very different relationship where he went from being Professor Ricker or Dr. Ricker to just Paul. Actually, there was a joke, North Pole and South Pole. But it was a very, very strange transition over the course of those six years. And I don't think that kind of relationship happens a lot in other lines of work. It's something very, very special in the sciences. It's a tradition that we've had since forever. since there's been a sciences. You can trace back your academic lineage, your advisor's advisor, your advisor's grand advisor, on and on and on. And this is how science is done. This is where scientists are trained in a very personal, very long-term relationship with an advisor. It doesn't really happen in the classes. It happens in that relationship with the advisor. So I wrote my dissertation, got my PhD.

And remember, when I went into grad school, I didn't exactly have a long-term plan. But as my PhD was approaching, OK, now what? OK, I'll give a crack at being a researcher. And that means getting a postdoc position, what's called a postdoctoral research position. These are temporary jobs used to see if you're really good enough, if you're as good as what you say you are, where you fly out from the nest of your advisor. You try to fly on your own a little bit before you're considered for a long-term faculty position. I had a chance at a job. I took it. It was accepted. And I was on a complete 100% academic research track until about two and a half years ago when I started Ask a Spaceman, this show that you're listening to. I started the show on a whim. I'd always been interested in trying it. And I just had a do or die moment. Let's give it a shot. And it changed my life. You've changed my life. And if you thought there was going to be a Patreon pitch, that's not here. It comes later. And I fell in love with outreach.

I fell in love with communication. I fell in love with sharing what I know and what I love about the universe with anyone who would listen and quite a few who don't want to listen, but they're going to hear it anyway. So now I still do research, but I am focused on outreach and communication. And I definitely wasn't trained in any of this. I didn't get a PhD in science communication because that's not a thing. I didn't have high school classes. I was taking computer programming in high school. I'm not trained in any of this. I'm learning as I go. I appreciate your patience over the past few years. This journey that you've gone on with me of I'm training myself to become a better science presenter so I can make science more accessible, more communicable, more There's a joke about diseases in there somewhere better for you so that you can understand the world that I've been immersed in for a really long time. Here's the point of my story. I didn't have a plan. I didn't have a plan and I did all the wrong things.

I made all the wrong choices to prepare myself with where I am right now. So looking back, I can tell where developing some skills, getting some practice would have been beneficial. But really, I was just winging it. I've been winging it like this feels good and I'm going to push as hard as I can in this direction. Oh, this feels good. I'm going to push as hard as I can in that direction. This feels right. I want to try it. And if it doesn't feel right, I'm not going to push in that direction anymore. And that's been the story of my career, of just my gut instinct, of what I seem to enjoy intersected with what my latent skills are. And then can I develop those skills and refine those skills over the course of my career? That was my experience. I can't tell you. That was a while ago. I got my PhD in 2011, graduated high school back in 2011. as practically ancient history may not be 100% relevant today. So maybe it is the case today that you need to make all the 100% right decisions. You know, if you're 13 years old, you need to start picking your classes, picking your extracurricular activities to get you down the path and that locks you in for the rest of your life.

I really hope that's not true because that's horrible and dystopian because human lives are fluid and imaginative and fun. And, uh, my life has been fluid and imaginative and fun. And I really hope the next generation scientists, uh, have are able to push in the direction of their dreams. That said, I do sit in meetings where we discuss new underground graduate evaluations and, and, uh, applications. I am on a graduate school fellowship committee for the Department of Energy. And so I see the applications I do every year. I get to see the crop of what the high schools and colleges are producing and how they're approaching these careers. So that gives me a little bit of basis that I can offer some recommendations. And these are recommendations in response to specific questions, specific questions like, do I need to take special math or astronomy classes right now, whenever right now is? Not necessarily. Obviously, you should be interested in this subject. But if I compare what I know about physics and astronomy and math and even computer science in what I know now to what I knew in 2011 when I got my PhD or 2011 compared to 2005 or 2005 compared to 2000, I would be frightened.

It seems like an unimaginable amount of stuff. And so I do have people emailing like, please help me. I want to read books. I need to get started. I want a career in astrophysics, so I just have to consume all the knowledge. It comes a little bit at a time, one class at a time. one homework set at a time, one exam at a time, one office hour at a time, one page of a textbook at a time, one conversation at a time, one video at a time, one article at a time. It's a little bit built up over decades where you build the base of knowledge so that you can talk about astronomy, so you can partake in the astronomical or astrophysical or physical conversation. professional world. It doesn't happen instantly, and nobody expects it instantly. Being a physicist is a skill that takes time to develop, a lot of time, maybe more time than most professions, so there's no rush. When I work with an undergrad research assistant, I give them different sets of problems. I have different expectations than when I work with a graduate assistant or when I work with a postdoc, when I'm collaborating with faculty, you know, a professor.

There's different levels. And even professors, maybe this is something outside their normal research line. It's always very fluid. We're always learning. There's a culture of you are always learning. There's also a culture of you are always wrong, which has some negative consequences on your ego, but also liberates you to be open to learning more. There's a culture of you are always learning. You're never done asking questions. Another question I get, is it important to get into a good school? Good is always hard to quantify when it comes to schools. There's various metrics that various organizations use. It's always recommended, of course, but it's not a deal breaker. And when it comes to good, especially when we're talking about graduate education, you're looking at good as usually means a large department, well-funded, good reputation. And your choice of graduate school has much more impact than your choice of undergrad. Nobody cares where I went to undergrad. Basically, nobody cares anymore where I went to grad school.

They care about the work I'm doing right now and the work I've done in the past few years. They don't care where I went to undergrad. But it's a ladder. Like, you know, every step matters for the next step. And then once you've reached that next step, nobody cares about the earlier steps. Quality of education in a graduate institution will be roughly the same. Of course, there are caveats. In fact, if you go to a large research-focused university, you might get a worse education than if you go to a university that only offers, say, bachelor's degrees where they're focused on education. That's because at the research universities, you might be taught by TAs more than the professor, teaching assistants more than the professors. The professors themselves will be more focused on research than actual teaching and education. There may not be a tradition of good pedagogy, of good teaching practices at the university. It varies from school to school, so I can't make general statements. But generally, at an undergrad, you're going to learn about the same stuff as any other place.

So you don't need to fret too much about undergrads. During your undergrad career, I do recommend you try to get at least some research experience. In fact, the National Science Foundation has a program called Research Experience for Undergraduates for exactly this purpose, where you spend a summer somewhere doing some small research projects so you can build up some credibility. So really when it comes – and so that's all I have to say about undergrad is do a good job, impress your teachers, and try to get some undergrad research in. Grad school is a little bit more important and it is better to get into a better school because those schools will have more funding. There's more options for advisors. There's more visitors giving seminars and more opportunities for travel to conferences. Why is this important? Because like all careers, it's all about the connections. You need to do good work. But it really helps to have someone very well-known vouch for you to say, yeah, yeah, this one's the one.

This one's pretty awesome. You should hire them. Those connections are very, very important, especially in a relatively small, relatively tight-knit community like the astrophysics community, like the physics community, like the astronomy community. A letter of recommendation from a rock star in the field is a golden ticket. that can open up many, many, many, many, many, many doors for you. And it's easier to get access to become a student of a rock star in the field because the rock stars in the field tend to be at the larger, better-funded universities. This culture of letter of recommendation writing is very strange indeed. It's very different from what you might experience or expect in the business world. Letters of recommendation, again, these date back for centuries in the scientific world, and it is how you get jobs, really. Because pretty much everyone has roughly the same GPA, like that even matters coming out of grad school, because most of it is research, it's not even your classes.

Just about everyone's done some level of research by the time they get their PhD. You know, they've written a couple papers. They've participated in a large collaboration, maybe. They've been to a few conferences advertising what they do. It's the letter of recommendation. And these are written in a very, very odd way. They are always exceedingly positive. If there is a hint of negativity in the letter, then that applicant is immediately dropped. And I should say, I should clarify, this is more the American style. The European style is much more cut and dry. And there can be issues if there's a European graduate student applying to an American school and their advisor writes a European style letter saying, oh yeah, this person's pretty all right. that will immediately sink their chances of getting into any job in the U.S. But these letters are very quantified. The letters will straight up say, and I've read and written letters like this, like this student was the third best student I've ever mentored.

But my fourth and fifth best students were so-and-so and so-and-so who went on to this university or this research position. And they had solid lives for themselves. So even though this person is number three, they're a really, really solid bet. They're great. And it's those letters that are the first and last thing they're read. Like you read the whole application. You pour through their academic history. You read their essays to make sure they are competent. You look up their research records. And it's just those letters are so important. And so that's why picking your advisor is so important because your advisor will give you The best letter. This is the person that knows you the best. They've had a direct experience with you for years. And so they're the best judge of your future prospects, of your quality. So getting into grad school, getting an advisor, having a good relationship with your advisor is incredibly important. And those letters just give you the better shot of making it to the next rung.

And if you make it to the next rung and do well there, then that opens up your chances of making it to the next one. Another question I get is, do I need money? Well, undergrad, typically, yes. You know, you need to pay for college unless you get some sort of scholarship or there's some financial assistance. Graduate school, no. You actually get paid to be there, usually from teaching assistantship. So you'll sign up for some department or you'll apply to some department. The department will take you on. You're both a student and an employee of the department. You usually have to teach on the side a few hours obligation per week. In exchange, that department will pay your tuition and give you a stipend. And if your advisor is well-funded, like they've got some money from grants floating around, then they can convert that teaching assistantship into a research assistantship. And then that means that instead of having to teach on the side, you get more time for research. And so that's why...

It's better to go to large, well-funded schools because there's more money sloshing around. There's a better chance your advisor is well-funded or your potential advisor is well-funded so that they can support your life directly and you don't have to teach on the side. But either way, you can always apply for fellowships. from National Science Foundation, from NASA, from Department of Energy. Fellowships are great because it's free money. They usually pay better than teaching or research assistantships. They are naturally very, very, very, very competitive, very difficult to get. But if you get them, you can pretty much say you can set your own agenda in grad school because it's your money. It's not your advisor's money. I can't tell you what to do. And so those are nice. Like I said before, it is exceedingly important to have a good advisor. They're your number one guide through the actual world of academic research. Their evaluation of you will make or break your career. Their connections will become your connections.

The people they collaborate with, the people they write papers with, the big collaborations that they're members of. Those are your initial set of contacts for the next job, for a faculty position, for an opening, for a postdoc, for whatever. They will be your champion. Remember, they hired you. They're spending money on you. They see you as an investment. They want you to do well. Their name goes on all the papers you write to. So they will defend you. They will defend your work. They want you to succeed. So they will, in general, write, unless it's a really toxic relationship, they will write you a very glowing letter. And they will push other people. They will call people and say, hey, I think you should hire this person. Oftentimes in a postdoc review committee or a faculty committee, they will straight up call your former advisor, your former mentor, and say, like, you know, tell me about the, you know, I read your letter. Is there anything you didn't put in the letter that you need to talk about? You know, because we're trying to make this decision.

And they'll be honest. They'll be honest. And that's just the way it is. Another question, what are the skills I need? There's an impression that you need to be really good at mathematics, that you already need to be good at science in order to become a scientist. But, you know, mathematics is incredibly important in the physical sciences, and the book of nature is written in mathematical characters. That's what Galileo said, and it's kind of accurate. But... Being good at mathematics is a skill that you develop over time. Being a research scientist is a skill you develop over time. And you don't get it all at once. So you don't need some great, incredible aptitude at the outset because you train, you spend 10 years figuring this stuff out. You will become a decent scientist whether you like it or not just through sheer force of will over the course of 10 years. And that, I think, is the number one skill. Force of will. Grit. Determination. You've got to want it. I'm going to be honest.

Being a physicist, being an astronomer is not an easy job. Doesn't really pay that well either. Patreon.com slash PM Sutter to help support this show so I can keep going and I can keep supporting all the education and outreach activities I do. Patreon.com slash PM Sutter. Thank you so much for your support. It's not a job that pays well. It's a pretty thankless job. It's not a very glamorous job. Scientists do it for the love of science because they're curious, and this is what it takes to be curious. And so the number one skill – and I've asked around. I've asked other faculty. I've asked postdocs. Just what do you think is the number one skill? And they say to a person, they say determination, grit, perseverance. Yeah. You need it to survive and you need it to break through because it's tough to justify the months of fruitless labor to get that one aha result. That takes guts, grit, determination, perseverance. You need it. It's the only way to make it through. Other skills, the mathematic skills, the analytic skills, the comprehension skills, the debate skills, the speaking skills, that comes with time.

You don't need it now. After 10 years, you'll have it. And you need hustle. You need to do good work and put it where people can see it. I mean, that's true in pretty much any job. There's about 50 papers written in astrophysics every day. Every single day, there's 50 new papers in astrophysics, plus or minus. Nobody can keep up with that. So you got to get to conferences. You need to talk to people. You need to introduce yourself. You need to give talks and defend your work and show people why it's a good idea and why their idea is a bad idea and be open to those debates, be open to being wrong and issue corrections and updates. And that takes hustle. You got to be out there. You got to be visible in the community so people know who you are. So it's like any other career, really. When it comes to careers, there's nothing that special about physics or astronomy. You need an interest or a passion. Otherwise, you never survive. And some base skills, at least a base level of aptitude, at least a base interest in willing to have an aptitude.

The rest comes later. It's part of the training. So I'm pretty much at the limit of how much I wanted to talk. I do have a few more notes about how there's basically no jobs in astronomy. What I think I'm gonna do is I'm gonna save that for a future episode. It won't be the next episode, But I do want to talk about the problems with the modern astrophysics career, physics and astronomy career, of how there are some institutional problems in the community that prevent people from succeeding. I do want to get into that, but I don't want to belabor that today. And so stay tuned. I'll do another episode. It might be a bonus episode. I may not go in the mainstream or something. Just stay tuned to that and we'll get through it. Before I go, I do have two quick announcements. One is Space Radio is live. It's happening. In fact, I just recorded an episode like an hour ago. And you need to go to spaceradioshow.com where you get to talk to me live. We record the show every Thursday at 4 p.m. Eastern.

You need to call 888-581-0708 to talk to me. Just go to spaceradioshow.com. There's all the instructions and info you need. So you can get on the radio and we can have a conversation about science. And the second announcement is AstroTour is back. That's right. With Fraser Cain. I know we're going to Iceland in February 2018. Now we're going to the Caribbean in September of 2018. And you need to come with us. You get to see Kennedy Space Center. Don't go on tour. You get to see the night sky like you probably have never seen before. You get special lectures and talks and show tapings with me, with Fraser Cain of Universe Today. And you get to explore mine ruins in Mexico and Belize. How awesome is that? It is significantly awesome. You need to go to astrotouring.com. Or you can just go to pmcenter.com, my website. That has links to everything. Thank you so much to my top Patreon contributors this month. Justin G., Matthew K., Kevin O., Justin R., Chris C., and Helge B. Thank you so much for your support and the support of everyone on Patreon and all the support for you for listening.

Please... Thank you for watching. adds up and it really, really helps. And I'm extremely grateful and keep those questions rolling in at 92 Rufino and Vicki K. Thank you so much for today's questions. You can keep those questions coming to Facebook and Twitter. My name is at Paul Matt Sutter. You can also use the hashtag ask a spaceman or email ask a spaceman at gmail.com or just visit the website, ask a spaceman.com. And I will see you next time for more complete knowledge of time and space.

AaS! 64: What fate awaits the Voyagers?

Why were the Voyager missions so important? Where are they now, and where are they going? What is their ultimate fate? And that Golden Record…good idea or bad idea? I discuss these questions and more in today’s Ask a Spaceman!

Support the show: http://www.patreon.com/pmsutter

All episodes: http://www.AskASpaceman.com

Follow on Twitter: http://www.twitter.com/PaulMattSutter

Like on Facebook: http://www.facebook.com/PaulMattSutter

Watch on YouTube: http://www.youtube.com/c/PaulMattSutter

Go on an adventure: http://www.AstroTouring.com/

Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!

Big thanks to my top Patreon supporters this month: Justin G., Matthew K., Kevin O., Justin R., Chris C., Helge B., Tim R., Michael C., Lars H., Ray S., John F., James L., Mark R., David B., and Silvan W.!

Music by Jason Grady and Nick Bain. Thanks to WCBE Radio for hosting the recording session, Greg Mobius for producing, and Cathy Rinella for editing.

Hosted by Paul M. Sutter, astrophysicist at The Ohio State University, Chief Scientist at COSI Science Center, and the one and only Agent to the Stars (http://www.pmsutter.com).

.

     

      Tweet #AskASpaceman

EPISODE TRANSCRIPTION (AUTO-GENERATED)

You know what time it is. It's time for Ask a Spaceman. I'm your host, Paul Sutter. You've got questions and I've got answers. You know how this show works, but let's travel out there one more time. You go online to Twitter or Facebook, use the hashtag Ask a Spaceman and send some questions and I will find them. You can also follow me directly on Twitter and Facebook. That name is at Paul Matt Sutter. You can also go to the website AskASpaceman.com, AskASpaceman at gmail.com, youtube.com slash Paul M. Sutter. So many ways to get questions, but really just one way to answer them. And that is through this show. We have one simple goal with this show. That is complete knowledge of time and space. And on the road to complete knowledge of time and space, we have today's questions. Rob H. via Facebook asking, what awaits the Voyager mission? Ryan asks via email, what is the sun's motion through the galaxy in the direction of Voyager? Wow. Voyager probes. This is historic. I'm recording this episode, by the way, near the 40th anniversary of their launch.

And it's hard to describe just how groundbreaking. Space-breaking? Yeah. Let's go with space breaking. It's hard to describe just how space breaking the Voyager missions were. And they happened at just the right time. It is such a cosmic coincidence, a lucky break at just the time that we were able to actually develop interstellar spacecraft, right? and launch them outside of the Earth's gravity well, send them into space, pack them with scientific gear that could take pictures, that could carry instruments to detect other things, be able to power it, and be able to communicate back with Earth. I mean, think of all the technologies that are packed into a spacecraft and how... 10 years before, 20 years before, 50 years before, 100 years before. That kind of package wouldn't just be impossible, it'd be inconceivable. Go back to the 1800s and try to explain to someone the concept of an interplanetary spacecraft. That's just not a thing that a 19th century mind could wrap itself around. But we're able to do it very, very quickly in the 50s, 60s, and 70s.

And at just the right time in the 70s and 80s, the outer planets lined up. That only happens about every 200 years. 200 years! So if we missed the window, say they lined up in 1910, we would have to wait another 100 years for this opportunity. The planets were in just the right orbit where you can launch them from Earth and swing from gas giant planet, gas giant planet, using the gravity assist to boost the spacecraft each time and kind of hop around like a monkey on a vine from tree to tree swinging from planet to planet. It didn't just make it easy, it made it possible. Because if the planets were on the opposite side of the solar system, you would get to visit one, maybe two. And, you know, that's an expensive mission no matter what, you know, politics and all that kind of stuff maybe just would have never happened. But we did get lucky and we took advantage of it. NASA took the Mariner design, which was very successful for Mars missions, and did two copies, two different spacecraft.

And those were the days when NASA could build two of everything. And sent them, these were the Voyager missions, Voyager 1, Voyager 2, launched from Earth. on a decades-long mission to explore the outer solar system. Do you remember the excitement from New Horizons when it first returned its images of Pluto? And just the fascination and the sense of adventure and excitement and curiosity and how we're seeing things that no one in human history has seen before. It was kind of like that times 10, right? Yes, we had the Pioneer missions before the Voyagers, but those cameras weren't nearly as good. Those were kind of just like test runs compared to the Voyager. The Voyager missions revolutionized our understanding of the outer worlds and brought... our solar system into the popular imagination. You know how like everywhere, like you can, I can just say Saturn and boom, you think of Saturn. It's because of the Voyager missions that I can say Saturn. And you don't just think of a little dot of light or a little blurry image.

You think of a detailed world with cloud bands in the rings and the moons. You can picture it in your mind because of Voyager. Voyager 1 just hit Jupiter and Saturn, plus visited Titan for a bit. Voyager 2 got to visit all four. To this day, by the way, to this day, Voyager 2 is the only spacecraft to visit Uranus and Neptune. Open up any book on the solar system. Search online, solar system. Go ahead, I dare you. If you look up, what is the picture of Neptune? That picture will be from Voyager 2. That's it. That's it. That's all we got, folks. It's hard to describe the amount of data gathered by those missions. It really opened up this frontier, this outer solar system. What New Horizons is doing now with the realm of Pluto and the Kuiper Belt, Voyager did for the outer planets. 30 and 40 years ago. There's detailed images of the Great Red Spot. There's the volcanic eruptions on Io. There's the cracks on the surface of Europa. There's impact sites on Ganymede. It's just, man. So much to discover and so many questions raised by this mission.

Like, what's going on there? What's over here? Why is this happening here? That all modern missions to the outer planets basically go back to the Voyager mission and say, hey, remember when Voyager detected this or saw this or we got this feature? Yeah, we want to figure that out some more. Voyager was the first one. It was not a short mission. It was launched in 1977, hit Jupiter in 1979, Saturn in 1981. Five years later, Voyager 2 gets to Uranus and finally Neptune in 1989. These spacecraft were built tough. They had to operate in the dead of space off and on for decades. And they spent a day tops at each planet. So cruising through space, doing nothing for years and then oh planet mission everything every all systems online full communication full power collecting data for a day and if it's gone they would loop around the total it spent about a month each spacecraft would spend a month around each system but the flybys of the planets themselves lasted about a day In that month, they would get images and detailed observations of the moons of those planets if there are lucky alignments.

But just think about a day like you've been waiting for years and then it's go time and then it's over in a day. The designers of the Voyager spacecraft knew that they would reach interstellar space. Spoiler alert, by the way. So they included a gigantic antenna dish. 12 foot diameter, that's 3.7 meters. That's a big antenna dish. And you're going to need it if you're going to be beyond the edge of the solar system and still communicate with Earth. And it just amazes me how much science and scientific gear the engineers packed into these spacecraft. Optical cameras, infrared and UV spectrometers, magnetometers, plasma wave antennas, triaxial flux gate magnetometer, which sounds way cooler than it actually is. Try saying it three times fast. Cosmic ray detectors, shields, thrusters, computers, targeting sensors, the works. So much stuff is packed into these spacecraft. And they're equipped to not just take pretty pictures, which are very pretty and also very useful, but really study the physical properties and the environment of these systems.

Remember, this was like a once-in-a-lifetime shot. They had to make it work. They had to make it count. They had to take data, they had to do science, gather as much information as possible. So not just a pretty picture of the atmosphere, but temperature differentials across different latitudes, magnetic field strength and penetration of the magnetic field, the whole deal, the whole deal. But enough of what they did. Where are they now? They're about plus or minus 13 billion miles from the sun. That's 21 billion kilometers. As if that means anything. That's just a large number to most of us. It's hard to picture that. That's 140 times further from the sun than the Earth is. Five times further than Pluto is. They've been trucking for a while. They've been going 30,000 miles per hour for 40 years. Some of the fastest spacecraft ever designed, and they've been cruising nonstop for 40 years. They're at such a distance from the sun that even the giant planets are just bright pixels in a grainy image.

Even here on Earth, if you pull out some backyard binoculars, you can see the disk of Jupiter. You can see the disk of the planet Saturn and its rings. Voyager has a much, much better camera than your backyard binoculars, but it's so far away, it can't even see Jupiter, Saturn, Uranus, and Neptune. One of the last images it took was what's called the family portrait, a series of images capturing each planet. And each planet is just like a little tiny dot. If you get out to the distance of Neptune and Pluto, that's like deep twilight. Like, you know, like say an hour into sunset where the sun has definitely gone down, but there's still some light left. That's what it's like at Neptune and Pluto. This is about 1 25th. of that level of light, that level of illumination. I can only imagine it's incredibly weird and isolating out there because the sun is also very small at these distances. It's just a point of light, just like any other star is a point of light, but it is still uncommonly bright.

It would still be painful to look at. You can definitely pick out the sun from the field of stars. Like, yes, that's the sun, but it's not a disk. It doesn't take up any area on the sky. It's just a thin point, but in an uncommonly bright point of light. And Voyager 1 really is in interstellar space. It reached it on August 25th, 2012. Voyager 2 is on the cusp of interstellar space. It'll reach there in 2019. How do we define interstellar space? You know, there's a few definitions that you could pick. The one NASA chose is a good one and good enough for my purposes. I would count this as truly interstellar space is based on the sun's influence, for lack of a better word. Not gravitational influence, that extends technically to infinity, but pretty far. But rather the bubble influence. It's the place where the solar wind meets the interstellar medium. The sun is constantly ejecting charged particles off the surface. And it floods. These charged particles flood our solar system. When they come to the Earth, they interact with our magnetic field.

They get funneled to the poles. We call them the aurora. But these particles extend way out into space, past the orbit of Neptune and Pluto, the Kuiper Belt, the whole deal. But our solar system is embedded in the galaxy, and the galaxy is filled with its own population of high-energy particles, you know, ejected from other stars, ejected from stars. supernova accelerated by magnetic fields. The whole deal, the whole deal. And there's a certain point where you can tell. It tastes different. Where you're like, nope, nope, this is the sun's. This is the sun's charged particles. And then... Nope, nope, nope. This is the galaxy. It mixes together. Almost as if I were to pass gas. No, in an elevator. I don't like that analogy. Let's say you were to pass gas in an elevator. There's a point where the expanding shell of gas coming out of you just mixes with the general atmosphere. And where there's a certain point, if you get further away, you couldn't even tell the difference. It's kind of like that, but made of charged particles.

There's a certain point where the bubble of our sun's influence just mixes and mingles with the galactic milieu. And we give names. Of course, this is astronomy, so we have to give names to everything. We have the solar wind. Eventually, the solar wind stops. It slows down where it meets the galactic interstellar medium. That's called the termination shock. Then there's a region called the heliosheath. and the heliopause after that, and the bow shock beyond that. And of course, it's not just a spherical bubble around us. Our solar system is moving through the galaxy. So it's compressed on one end and extends out the other. Kind of looks like a tadpole. That's our little region, our little tadpole region. For Voyager 1, there are multiple crossings, multiple crossing events where you could tell the difference between the solar environment and the galactic environment. So that suggests that it appears to fluctuate. It wibbles and wobbles back and forth. And that's new stuff, by the way. Voyager 1 is the only one to do that ever.

So we're basing this totally on its observations and its detections. We had no idea where the termination shock might be. We had no idea how thick the helio sheath might be, where it begins to mix from the solar environment to the galactic environment. This is new stuff. And that's pretty cool. So that's in addition. to the Voyager probes, and especially Voyager 1, opening up our outer solar system, reveals what's going on at the very edge of the sun's influence. It really is an interstellar space. It is beyond the influence of our own sun. It is the furthest human-made artifact. We are still communicating with Voyager 1 very weakly. Its power source is dwindling. Obviously, solar power isn't going to get you very far out here, so it has what's called a radioisotope thermoelectric generator. Pretty straightforward concept. You take a lump of radioactive plutonium, stick it in one end of a piece of metal, a semiconductor, and it will heat up the metal. But because you actually have two pieces of metal glued together, they're slightly different materials.

One will heat up faster than the other. because of the heat from the plutonium. And if you have a metal that's hot on one side and cold on the other, you get a flow of electrons, and a flow of electrons is called electricity. So it's pretty easy, straightforward device. It gives long-lasting power. It's like a nuclear battery. That's a good way to think of it. It doesn't last forever, though. One by one, we've been shutting off its systems. We shut its cameras off pretty early. Those are pretty power hungry. Just have a couple detectors, especially to study this helio sheath and helio pause and the bow shock and the determination for all that good stuff at the mix at the boundary between our solar system and interstellar space and to communicate back with Earth and to run the computers. So it's been on low power mode. We can still communicate with Voyager. And by 2025, there will not be enough power to run the antenna. It's a radio antenna, so it will go silent. It would be so quiet. It can't even contribute to Patreon.

Patreon.com slash PM Sutter is how this show and all my education outreach activities are funded by you, the audience, by my supporters. I can't thank you enough. It is your contributions that keep this show going. So thank you. Patreon.com slash PM Sutter to learn more. But Poitier can't even do it. It can't log in. It can't upload its credit card information to make that monthly donation. And eventually its credit card will expire and then it's bad news. So Voyager 1 is outside our solar system. according to that definition of the boundary between the solar wind and the interstellar medium, between the particles ejected from the sun and the particles that are just in the general galactic mix. There is, however, stuff associated with our solar system that's out there. There's the Oort cloud. The Oort cloud is a thin, diffuse shell of frozen debris that was kicked out when our solar system was formed. This is the home of comets that take tens of thousands or millions of years to complete their orbits.

There'll be these little rocks, frozen rocks, Hanging out in the distant parts of the solar system, they can get perturbed, they can get bothered, and they can fall in and swing in towards the sun. It will take about 300 years before Voyager 1 reaches the inner boundary of that Oort cloud. These are objects living in interstellar space, but still gravitationally bound to our sun. Voyager 1, however, is not gravitationally bound to our sun. It will keep going and going. It will never return. It will eventually pass by another star coming within 1.6 light years of a star called Gliese 445. And you know what? That sounds super far away. But when we're talking interstellar distances and galactic scales, 1.6 light years is pretty close. That will happen, by the way, in 40,000 years. Voyager 2 should reach interstellar space, we think, in about 2019, depending on its exact boundary of the heliopause. It, too, will pass by a star in about 40,000 years. It will come within 1.7 light years of Ross 245.

It will also come within 4.3 light years from Sirius, the brightest star in the sky. That will happen in 296,000 years. And then nothing. That's it. These are galactic scales. These are interstellar scales. And I love introducing the topic of Voyagers. I love talking about the Voyager probes in talks because it really hits home what it means to be interstellar, the true scales of our galaxy. It's like a punch in the gut when you really think about it. It took 40 years for Voyager 1 just to reach the edge of this bubble and see, like, oh, space isn't that big. That's four decades. That's not so bad. Oh, and then to even reach another star, 40,000 years. And then that's it. It's hard to predict, of course, because there is some chaotic motion to star movements. You know, new stars can be born and die. There can be molecular clouds that disrupt. But we're pretty sure it's never going to get that close to any other star ever. Our Milky Way galaxy is made up of hundreds of billions of stars.

And Voyager 1 and Voyager 2 will never encounter another one. Ever. Ever, ever, ever, ever. That's it. Forger one got to be close to our son and get to be close to Glees 445. Forger two will get close to Ross 248 and then kind of sort of close to Sirius. And that's it. The sun is sitting about two-thirds of the way out from the center of the Milky Way galaxy, situated on what we call the Orion Arm, one of the spiral arms of our galaxy. The sun itself has a speed of around 200 kilometers per second, so the speed of the Voyagers is that plus 38,000 miles per hour, which is still 200 kilometers per second, about. The Voyager probes themselves were launched going in front of the sun, so they take the speed of the sun, plus that they're kind of going out ahead of us. They really are voyaging out ahead of us. Going slightly up-ish and slightly down-ish, the interactions they had with the planets sent them on these slightly different trajectories. So they're not gonna keep going straight ahead of us in the galaxy in our direction, in our own orbit around the Milky Way, so they'll go up and down a little bit.

In 200 million years, they will circumnavigate the galaxy once. 200 million years after that, they'll do it again. It's weird to think about if you were attached to the Voyager spacecraft, wouldn't you be dead? But let's assume you were alive. Just the loneliness of being out there. Where slowly year after year our sun gets dimmer and dimmer and dimmer until you can't even tell it apart from the field of stars that surround you. And then dimmer still so you can't even pick it out. You can't even see it. And then dimmer still where you can't even pick it out with a telescope. And you'll pass by some other stars. Some will get brighter. Some will get dimmer. But that's it. You're never falling into another solar system. You're never seriously encountering another object. Nothing bigger than a microscopic grain of dust. A cosmic ray here and there. That's all you'll ever touch. That's all the Voyager spacecraft will ever touch. The story... of the voyager spacecraft isn't quite over even though their mission will end in 2025 no more communication no more data that we can acquire from those spacecraft there is something else on both spacecraft there's uh tucked between the instruments on the side is a small golden disc And we've etched some carvings into those disks.

Diagrams of people. You know, there's the dude waving high and the lady just standing there. Same as the pioneer plaques. The location of our sun relative to nearby known pulsars. And there's some basics about the hydrogen atom and the 21 centimeter emission line. Some basic facts that we think are totally universal. And there's some instructions. There's a little pictogram. And you could, it's hoped, look at this pictogram and realize that they're instructions. And if you follow the instructions, you end up assembling a spinning platform and a little stylus. And then you can take this golden disc, set it into that spinning platform and set the stylus in the grooves that are etched into the disc and start spinning the disc. And the stylus will start vibrating. And then you can interpret those vibrations as sound waves. And you could listen to those sound waves and those sound waves would carry information. There'd be some basic facts again, kind of establish what's going on. And then you would start to hear voices, sounds of nature, you know, crickets chirping in oceans crashing against the shore.

And then you'd hear music. There's a selection of songs placed on these interstellar spacecraft. It's taken from around the world. If I had to judge it, it seems kind of biased towards Western classical music. But there's a lot of cool stuff on there. And apparently, you would be wowed and brought to tears by that selection of music. And... This is like this is considered it was considered an emissary of Earth. Like, OK, definitely this golden record is going to outlive the designers and creators. It was led by a committee led by Carl Sagan, Frank Drake, you know, all the usual suspects. And it will definitely outlive them. And, you know, there's a pretty solid chance it's going to outlive humans as a species. And so like this is it. It's like a time capsule. of our time here on earth and an emissary like here's a little slice of our world a little slice of what we experience and a little slice of of us of our own culture of our own values of of who we are there's lots of recordings of people saying hi in various languages and the the the hope is the romantic hope is that you know someday eon literally eons from now Some civilization might encounter a Voyager spacecraft, recognize the golden record for what it is, follow the instructions, construct a spinning platform, look at the vibrations on the stylus, correctly interpret them as meaningful information, listen to the sounds and be like, oh, wow, okay, cool.

I honestly can't decide. If the Voyager golden records are this bold, noble emissary into the great void, the everlasting record of humane, a small piece, as small as it could be, as it is, it's still a part of us, and it's now permanently a part of us. So even in four billion years when the sun consumes the earth, when it dies, we've still got the Voyager probes out there with a little piece of our culture and who made them. I can't decide if that's cool or kind of silly because we know that those Voyager spacecraft are not going anywhere anytime soon. And the chances of the Voyager spacecraft coming within range of any star system are literally astronomically small, let alone one that is full of intelligent beings that could spot the Voyager spacecraft. They are kind of small after all. Toe it in, do all the stuff, gather meaningful information, and actually listen to the golden records. So it's... It's kind of, in one view, it's kind of self-serving and narcissistic. Like, oh, we need to make our mark on the universe.

So we have to send the golden records out just on the off chance that someone will encounter them. They have to know that we were here. They have to know that we existed. That seems, I don't know, that just strikes me as narcissistic and self-serving. Like, we're not doing it for them, whoever might encounter it, whoever they are. We're doing it for us to make ourselves feel good. But on the other hand, it's kind of noble and beautiful and poetic that we do have this emissary out into the great void. So is it a good idea or a bad idea? Is it silly or noble? I honestly don't know. I go back and forth. And I'd love to hear your thoughts on Twitter and Facebook. Go ahead and shoot me. What do you think? What do you think of the Golden Records? Good idea or silly idea? Let me know and I'd love to have that discussion with you. Thanks so much to my Patreon contributors this month, especially my top ones, Justin G, Matthew K, Kevin O, Justin R, Chris C, and Thanks to all the Patreon contributors, patreon.com slash pmsutter for more info.

And of course, thank you to the people who asked the questions for today's episode. Rob H. on Facebook and Ryan S. via email. Beautiful subject, the Voyager missions. The scientific return is enormous. Thoughts of where they are and where they will be. very sobering and then open up this interesting question on the voyager golden records thank you so much thanks again you can follow me on twitter and facebook directly at paul matt sutter love to hear your thoughts on this episode you can also go to the website ask a spaceman.com send questions to ask a spaceman at gmail.com go to youtube.com slash paul m sutter go to itunes and submit a review that really helps the show's visibility i really appreciate it and i'll see you next time for more complete knowledge of time and space