AaS! 71: Who lives in the particle zoo?

What strange creatures inhabit the so-called “particle zoo”?  Why is it a zoo instead of something simpler? Is there anything that connects the forces and particles of our universe? I discuss these questions and more in today’s Ask a Spaceman!

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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., SkyDiving Storm Trooper, Lars H., Khaled T., Raymond S., John F., Anilavadhanula, Mark R., and David B.!

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).

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We've all heard stories of dystopian worlds, whether in the future or from our own past, like stories of the oppressors and the oppressed, of the haves and the have-nots, of the rulers and the ruled. And we have examples of these stories from medieval Europe, or we have stories of the far future, of, oh, it's going to be a horrible future. We hear a lot of these stories. I'm going to tell you another one of these stories of such a dystopian realm. But this world doesn't take place in the past. It's not from history and it's not in the future. This world is right here. It's all around us. But it's hidden from us. It's buried underneath layers and layers of powerful forces and energies. And only the most powerful experiments reveal the true nature of this reality. In fact, we knew hardly anything about it until about 100 years ago. We finally had the techniques developed where we could probe the subatomic world. Where we could probe the actual atomic world. It was only like 100 years ago or so that we realized that atoms were a thing.

And that there's stuff beneath atoms. Atoms are not the most tiniest, building blockiest things in the universe actually made of stuff. And what goes on beneath the level of atoms is crazy complicated. I mean, I'm not even joking. It is insane how complicated this stuff is, but I want to tell you a little story to get across the essence, the main essence of what's going on down there. We'll start at the top, the royal family, the top dogs, the big cheeses, the most powerful, rich, influential, dominant players of the subatomic world. It's the quarks. The Quarks are like any royal family. They're large. They're extensive. They're constantly infighting. There might be some examples of inbreeding. Like if you've seen like a family tree of royal families, you know what I'm talking about. There's claims to the throne. There's petty intrigue. All sorts of juicy court politics. in the quarks, amongst the quarks. The royal couple, the two at the top, themselves are called up and down. Up and down, the names we give to two of the quarks that sit at the top of the heap.

Between them, between those two, they form the most common, stable agglomerations in the universe, the protons and neutrons. Protons and neutrons are made of quarks of these royal couples, but it's not just two. For some very weird and complicated and deep reasons, this royal couple, they actually form triplets to form protons and neutrons. So they bind together. If you have two ups and a down bagged together, that gives you a proton. If you have two downs and an up, that gives you a neutron. And these quarks, these up and down quarks, rule the protons and neutrons. These are like the impregnable fortresses of the subatomic world. They are long-lived. They are stable. They are difficult to crack apart, protons and neutrons. But they don't get that strong from the qualities of the quarks themselves. They get that through the strong nuclear force themselves. The up and down quarks, these top two of the royal family, they rule by the power of the strong nuclear force. The strong nuclear force is so strong, its binding is so strong that it doesn't only form protons and neutrons, but it forms nuclei themselves, atomic nuclei.

It's able to bind together protons and neutrons. Two protons have the same charge. They would normally hate each other, but the strong force is able to overwhelm that. And It's because of this strong nuclear force that the strong nuclear force binds together the quarks, these ruling couple, the up and down quarks. And it's so strong that it leaks out of that range of the proton neutron is able to bind them together. So you can imagine the protons and neutrons are like the palaces, the fortresses, the keeps, the most powerful, the strongest part of the castle. And if you string a few of these castles together, like a few watchtowers together, you can get a whole castle complex on top of a hill. And that's the atomic nucleus. And like I said, it's only the most violent reactions that can bring down the walls, that can tear down the walls formed by the strong nuclear force that keep the up and down quarks safe in their cozy little palaces. The strong force is over 100 times stronger than any other force in the universe.

Over 100 times stronger. You just can't mess with the strong nuclear force. But it does have a trade-off. Even though that strong nuclear force can build these immense, powerful, strong castles, its range is limited. Inside the nuclear fortress, the strong force dominates all reactions. But outside, if these up-and-down quarks, these king and queens that are ruling the subatomic world, if they want to communicate or influence anything else outside of their fortress... They need to use other forces. The strong force provides not just the glue, the connection between the quarks, but also the mass. The mass of a proton isn't in the mass of the quarks. If you add up the mass of the quarks, you don't get the mass of a proton. You get something much, much smaller. But energy is mass. Mass is energy. We learned this from relativity. And This is how we get the mass of a proton is through the energy of the strong force itself. That's how strong it is. So it's like the castle isn't just the king and queen.

It's not just the up and down quarks. It's the walls and the bricks and the mortar. It's all the stuff. And it's the strong force that's actually putting that up. And so the mass of the castle is much more than the mass of the people that live in it because of the walls itself. Outside this castle, outside this castle is the great teeming masses of the peasants, of the underclass, living in poor little hovel villages clustered around those castle walls. And I'm talking about the Leptons. The leptons are the ones that do the work. If you've ever heard of chemistry, it's because the leptons are doing the thing of chemistry. If one castle, if one nuclei wants to communicate with another castle, it exchanges leptons. It will throw them back and forth, left and right. It will give up leptons, acquire leptons without a second thought. Doesn't care about the welfare, about their needs, their wants, their desires, their hopes, their dreams. They're just there to get the work done while the up and down quarks sit safe inside their castle walls.

The leptons are the ones doing the work. There's three leptons. The electron, the muon, and the tau. The electron I suspect you may be more familiar with. The muon is just like the electron, but bigger. And the tau is just like the electron and the muon, but bigger still. And the reason you don't encounter the muon and the tau all that often, why you tend to find electrons much more often, is that there's a rule in our universe, the rule in our universe, and especially in this realm, is that only the lightest survive. If you get too big, if you get too fat, if you get too wealthy, if you get too rich, you will be cut down. You'll be taken down. You are unstable. In this world, only the poorest survive. Only the smallest and weakest survive. If you're too massive, you are unstable. You will be torn apart into more fundamental particles. So the muon, even though it's exactly like the electron, it's like a peasant that's starting to get a little rich. Maybe they have a few businesses. Maybe they own a ship or something and they become a merchant.

That's not going to be allowed. They're going to be cut down. They're going to be taxed. They're going to be violent mobs. They're going to be unstable and they'll be torn apart into more fundamental particles. The electron is the lightest of the leptons. It's the poorest. It's the weakest. And so that's the one that gets to survive. This rule applies to the quarks too. I mentioned the whole quark family. There's actually six quarks. Six quarks, but only two of them, the up and down, are the ones that we encounter in protons and neutrons. The other ones, top, bottom, strange, and charm, are much more massive, hence they're much more rare. So even though up and down quarks get to rule as the royal couple, Paradoxically, they get to rule because they're the weakest ones, because they're the least massive ones, the least powerful ones, because anything bigger, any other heavier quark, if it forms, will immediately be cut down to size, just the same as it happens with the leptons. So you know what? In the subatomic world, it's the small guys ruling other small guys.

And that's just how it works. So you have a castle. Formed from the strength of the strong nuclear force, inside of it are the ruling family of the up and down quarks. Outside of the castle walls are the electrons, the leptons. So how does – if the strong force can't extend beyond the castle walls – How can the up and down quarks communicate with the leptons, with those electrons working the fields? How can they coordinate them? How can they tax them? How can they communicate with other castles over the horizon, over the hill? They have to use another force. They use the royal messengers. They use the photons. The photons are the carriers of the electromagnetic force. The photons are massless. The photons travel at the speed of light. The photons have infinite range. Of course, the farther you are away from the source, the weaker it will be, the fewer photons will reach you. But in principle, and even in reality, right now there are photons reaching us from the distant edge of the universe.

Photons are born, they travel, they die. They have only one goal, is to carry that electromagnetic force. They are able to communicate outside the castle walls so they can exchange messages between the royal family and the peasants outside. They can communicate from one castle to another, one atom to another, one atomic nuclei to another. They can travel across the universe carrying their very, very important messages. of either repulsion or attraction, doing what photons do. But not all particles can listen to a photon. These royal messengers, as important as they are, not everybody hears the message. If A particle is uncharged. If it doesn't have any electric charge, it is invisible to the royal messengers, to the photons. The photons can only communicate with a particle if that particle has some sort of electric charge. So what is the royal couple to do if they want to rule from their castle? They can't communicate with every particle in the universe outside their castle walls. What are they going to do? Well, they turn to their secret spy network.

They turn to gravity. Gravity is also massless. Gravity also travels at the speed of light. Gravity also has infinite range. And gravity sees everything in the universe. All matter. All energy. Everything. Nothing escapes the ever watchful eye of gravity. But gravity only communicates like a good spy in whispers. By far, gravity is the weakest force, 10 to the 40 times weaker than the strong nuclear force. 10 to the 40 times weaker than the strong force. That is weak. So that's the trade-off. Even though gravity sees everything, charged, uncharged, big, small, nearby, far, gravity sees everything, but its influence is very weak. It's very tiny. The up-and-down quarks in their castle keeps, in their fortresses, they can technically see everything in the universe. They can respond to everything in the universe. but not very strongly, because these spies only whisper. We have our castle keep with the strong nuclear force inhabited by the royal family of the quarks. We have our peasants on the outside, coordinated by the photons.

We have gravity, the extensive spy network, living on the fringes of society. are the ultimate untouchables, where even the peasants will turn their noses down at these unfortunate. These are like the leper colony of the medieval world, of the subatomic medieval world. These are the neutrinos. The neutrinos, once again, have three families. The electron neutrino, the muon neutrino, and the tau neutrino. They are leptons, just like their cousins, the electrons, but much less significant. They don't get to live in the villages. They don't get to cluster around castle walls. They're forced to travel, to roam the countryside. They can't be bound to anything, which can be bad, but also kind of good. Because they don't have any charge, they don't follow orders from the royal messengers, the photons. They ignore the quirks as much as they can. They can even come and go through the castle walls. That's how stealthy they are. That's how, like, they're just simply not noticed. Nobody cares if a neutrino is around.

Oh, did you feel that? What was that? Oh, that was nothing. I don't know. Maybe it was a neutrino. I didn't even see it. Whatever. Let's get back to feasting. Neutrinos are so lowly. that for a long time, we didn't even think they had mass at all. And it's only relatively recently that we discovered that neutrinos do have a little bit of mass. As invisible as they are, they do sometimes cause trouble. They do sometimes act as saboteurs because they can come and go through the castle walls without too much notice because everybody ignores them. Sometimes they do interact with a quark. And when they do, it causes havoc. One of the reasons they are so slippery is they don't even have fixed identities. They can wear masks. You never quite know what kind of neutrino you're looking at. You can look once and you say, that's an electron neutrino. You finally notice it. You finally pay attention to it and it's an electron neutrino. You look again and it's a tau neutrino. Travels a little bit across the room.

Now it's a muon neutrino. The neutrinos are strange beasts indeed. They can transform their identities. They can cycle through these three identities as they travel, as they propagate. That's how slippery they really are. There's this rigid hierarchy in the subatomic world. We have the collections of protons and neutrons, which we call atomic nuclei. The protons and neutrons are incredibly stable when they're bound to those nuclei in their fortresses with the electrons in the villages outside. Occasionally, order does break down. In this rigid, stratified, oppressive society, a neutron can defect. A clump of quarks that we call a neutron can escape the castle walls. Roam out into the countryside. Sometimes an electron can make it through the front gates and start roaming around the castle and eating all the food supplies and putting on gowns and suits. I don't know what you do inside of a castle. And sometimes a neutrino can completely slip through the defenses unnoticed. Who's there to do the dirty work? Who's there to clean up the messes? Well, the royal messengers, the photons, certainly aren't going to do it.

They're much too proud for that. They've got a job to do. The strong force is there, but it's too busy keeping the castle walls glued together. And besides, it has limited range. Gravity, gravity is all pervasive, but it's too weak to really do anything. There is one more force. to handle the rogue particles, say neutron defects from the castle, to deal with the occasional neutrino or electron incursion. And those are the Patreons. That's right, the loyal Patreons keep order in line and keep society functioning. Go to patreon.com slash pmsutter to learn how you can support this podcast and all my education and outreach activities. I really do sincerely appreciate all the support all of you have given me. over the years, and that's patreon.com slash pmsutter. Anyway, who does the dirty work that nobody else is willing to do? It's the special forces. The W and Z bosons. That's how special they are. They don't even have cool names, like photons or gluons. They're just W and Z, the carriers of the weak nuclear force.

The bosons, these W and Z bosons, the special forces are capable. They have a very, very special power that nobody else has. They're capable of transforming one kind of quark into another. They see an up quark, they can turn it into a down quark and vice versa. What does this mean? This means that they can transform protons into neutrons and neutrons into protons. This means that if an electron enters the atomic nucleus, enters the castle walls, or a neutrino does, they can use that to their advantage. They can use that to flip a neutron to a proton, a proton to a neutron. They're the only force capable. Of that very special exchange. Think about that. The weak nuclear force, probably the worst named force where it's just not getting a lot of it's not getting a lot of justice. It should be called the special nuclear force. I'm going to start. We should start right now just calling it the special nuclear force because it's how cool it is. What other force can communicate with quarks and communicate with leptons? Who? Nobody.

Well, I know the electromagnetic force can do it if they're charged, but who else gets to talk to neutrinos? Who can talk to a top quark one day, an electron another day, and a neutrino another day? It's the weak nuclear force. That's how cool it is. But that's why they really are the special forces. They do the dirty work that nobody else is willing to do. There is, in this world, a resistance. The anti-particles. All particles, the leptons, the quarks, everybody, have a mirror version of themselves where everything is the same, but the charge is reversed. Charge here doesn't always mean what you think it does. It can mean electric charge. I'm going to give you another example of a different kind of charge later on in the show. But you just take like all the mass is the same. The spin is the same. Everything is the same. But you flip the charges and you get an antiparticle. Matter and antimatter used to be in parity in the very early universe. There were equal amounts of matter and antimatter.

But something happened we don't fully understand. Feel free to ask. In the early universe to tip the scales to give the universe more matter than antimatter. Nowadays, antimatter is only occasionally formed here and there. From high energy reactions, whether in our laboratories or in energetic events in the universe, occasionally you will get antimatter formed. And when that happens, they are incredibly destabilizing, incredibly destructive. The last thing this structured, ordered society wants... is an antimatter particle floating around. Because as soon as an antimatter particle meets a normal matter particle, boom, a tremendous amount of energy is released. And you don't want that. You don't want energy released near your castle walls or in your peasants. As much as you hate the peasants, they still need to do the work of farming the fields and communicating with other atomic nuclei. So you got to keep them around. Would hate for them to go. You certainly can't have your castle walls destroyed because then that means you disassociate as an atom and anti-particles have the energy to do it.

So it's a good thing for these up and down quarks. ruling from their palaces and castles and their strongholds and their keeps and their fortresses, that there isn't a lot of antimatter around. There's one last aspect to this subatomic world. The shadow government. See, the up and down quarks... Think they're in charge, sitting inside of their protons and neutrons with their strong nuclear force, almost entirely resistant to any other force, to any other energy. But you know who's really calling the shots back there? The Higgs. The Higgs is the real power behind the throne. The Higgs is what gives both the leptons and the quarks, both the electrons, top, down, up, bottom, strange, charm, tau, muon, all of them. It's what gives them all their mass. The interaction of an electron with the Higgs field is its mass. The interaction of an up quark with the Higgs field is its mass. Without the Higgs, this whole society would break down. Nothing would make sense. The particles would not have their distinct abilities anymore.

and identities without the Higgs being present. And simultaneously, the Higgs allows for the splitting of the forces. If without the Higgs, we wouldn't have a separation between the electromagnetic and weak nuclear forces. We wouldn't have a separation between photons, the royal messengers, and the special forces, the WNC bosons. They would all be the same and it would be its own thing. And we wouldn't have the rich chemistry and interactions that we know in our real universe without the Higgs. So yeah, it may look like the up and down quarks are the rulers of the thrones, but there's someone right behind them whispering in their ear telling them what they need to do. This story... of the up and down quarks, the other quarks that really don't get to participate in normal everyday reactions, the electrons, the taus, the neutrinos are organized by what we call the standard model of particle physics. It's not really a theory per se, but like a framework of related theories. where the machinery for understanding all this comes from quantum mechanics and comes from special relativity.

You marry those together, you get theories called quantum electrodynamics, quantum chromodynamics, and this is how we understand the electromagnetic force, the weak nuclear force, and the strong nuclear force. There are many things, as it is a huge accomplishment of 20th century physics to work out what is going on at these incredibly tiny scales. But As much of a success as it is in something worth celebrating, something where researchers have received multiple Nobel Prizes for over the decades, there are things that the Standard Model does not explain. Things like neutrino mass. Things like gravity. Things like the nature of dark matter and dark energy. There are known physics that we have yet to incorporate into the Standard Model. What will it look like in the future? How can we extend the Standard Model or possibly replace the Standard Model with a whole new picture? We have no idea yet. That's a separate show. Besides the physics that we know that exists but we haven't incorporated into the Standard Model, like gravity, like neutrino mass, like dark matter, there are some other kind of overarching mysteries about the Standard Model.

Like, why are there three generations of matter? Why are there always three sets of particles? Why do we always get triplets of particles that have the same properties but different masses? Like the electron, the muon, the tau. Like the electron neutrino, muon neutrino, and tau neutrino. Even the quarks themselves, there's six quarks, but they're split into two families, subfamilies, groups, dynasties, whatever. Up, charm, and top all have the same charge, same properties, but different masses. And then down, strange, and bottom all have the same charge, but different masses. Why? Why? Who picked that? Why do we get that one? Why is that our universe instead of something else? We don't know. Why do we have four forces of nature instead of more? Why is there this huge discrepancy where the strong nuclear force is over 100 times stronger than anything else and where gravity is 10 to the 40 times weaker than anything else? Why? We don't know. There are a lot of mysteries in this universe.

The Standard Model is a huge success, painted this wonderful picture of our universe, but we don't fully understand it. And we don't fully understand what else is going on. There's one other thing I want to mention in this show before I go. And I couldn't figure out how to shoehorn it into the little mini narrative, the little picture of the medieval oppressive society that's happening at the subatomic world. And so here it is just kind of awkwardly tacked on to the end. And that's something called color charge. I did mention earlier that in anti-particles, when you take a particle and you keep everything the same, but you flip the charge. And it's not always just electric charge. There's something else called color charge that particles can have. And it's a horrible name, but we're going to go with it. Just like the electromagnetic force talks to particles via its charge, the amount of charge on a particle tells you how much it will respond to the electromagnetic force. Well, through experiments, we found out that there's something else that gives particles the ability to respond to the strong nuclear force.

And we decided to name a color because you need three of them to make a whole set, like primary colors, like red, green, blue, you need to mix together to make white. Well, you need three quarks to mix together to make a proton or a neutron. But there's complications. There's complications because you can also put a quark up with an anti-quark and they cancel each other out to give white. And you can solve a bound particle because a strong nuclear force is really complicated like that. Really, the strong nuclear force should be called the color force. It's what binds quarks together to form protons and neutrons and other groups of particles. It's so strong it spills out to bind them together to make atomic nuclei. The color force, not the strong nuclear force. I just wanted to mention that it really, really the strong nuclear force deserves its whole episode. But I wanted to just paint that little mini picture so you have some idea of what's going on. If you want to talk about color force, color charge, strong nuclear force, feel free to ask.

I'd be happy to do a whole entire episode on it. I just wanted to put that in so you have a complete picture of what's going on in the Standard Model. As depressing, as horrible, as dismal as that world is, that's the world we live in, subatomically speaking. I'd like to thank my top Patreon contributors this month, Justin G., Matthew K., Kevin O., Justin R., Chris C., and Helga B. Go to patreon.com slash pmsutter to learn more. Also, Astro Tours are a go. You need to go to astrotours.co. That's astrotours.co for more information. We have tickets available for the cruise, the Caribbean cruise with Fraser Cain and and the Atacama Dark Sky Expedition in December of 2018. Go there right now and make a reservation and then decide later where all the money is going to come from. It's going to be an amazing trip. I'm excited for both trips. They're going to be fabulous experiences. And I'd really love to share it with you. And space radio is also a thing. Go to spaceradioshow.com. We have tons of fun every week.

You need to try out that show if you haven't already. And of course, thank you to the listeners who asked the questions for this episode. We've got Alessandro M via email asking for an overview of particle theory in the Standard Model. Roger on the website asking about particle letter soup. Martin N on Facebook, what's beyond the Standard Model of particle physics. At Dan Chin on Twitter, please go into more detail on the forces. What are they? And at Pozoker on Twitter, can you please do an episode on the strong and weak nuclear forces and how they can help me be a better person? I missed that part. I missed that part about being a better person. You're just going to have to figure that out on your own. You can ask questions by going on Twitter and Facebook using the hashtag AskASpaceman. Also go to the website, AskASpaceman.com. You can also follow me directly on Twitter. My name is at Paul Matt Sutter. That's also good on Facebook too. You can go to YouTube. Go to YouTube.com slash PaulMSutter for...

All sorts of cool videos. Super fun. Doing lots of collaborations recently. Lots of cool stuff. If you can't donate, then I beg you to go to iTunes where you can give the show a nice little rating and tell other people about it. See you next time for more complete knowledge of time and space.

AaS! 70: Can we have some quark stars, please?

How does degeneracy pressure work? What kinds of particles exist below the level of neutrons? Can they hold up a star against gravity?  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.co/

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., SkyDiving Storm Trooper, Lars H., Khaled T., Raymond S., John F., Anilavadhanula, Mark R., and David B.!

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).

All Episodes | Support | iTunes | Google Play | YouTube

EPISODE TRANSCRIPTION (AUTO-GENERATED)

I want you to know that I do have standards when it comes to this show. Don't get me wrong. It is very, very minimal standards. And it's basically, I have a set of notes. So, yeah. I was developing another show. I had planned this episode to be totally devoted to the idea of quantum entanglement. And it was going to be awesome because it's a really, really cool concept with lots of intricate physics. But as I was prepping it, as I was reading, as I was taking my notes, it just... I wasn't liking the metaphors. I wasn't like the direction I was going in. I couldn't come up with any good jokes, even bad ones, especially bad ones. And I decided to pause it. And I decided to put it off. Maybe next month, maybe six months, maybe like 10 years from now. I don't know when I'm going to get back to it, when I'm going to feel happy with the subject of quantum entanglement. So I thought, instead, I'd just do something fun and lighthearted and easy, like, I don't know, QuarkStars. And I guess when it comes to the world of Ask a Spaceman, QuarkStars qualify as fun and lighthearted entertainment.

Well, it turns out as I was digging into the world of quark stars and figuring out and I really want to explain it to you. You know, the cool physics is happening with quark stars. Halfway through that topic, I found myself talking about entanglement. And here we are. I need to mention Entanglement in order to get across what I need to talk about with QuarkStars, whatever the heck those are. But I don't want to actually dig into the topic of Entanglement because I got entangled in it in a very bad way. And I want something better for all of us. So what I'm going to do, and that's the reason I'm kind of prefacing this episode with this discussion, is I'm going to allude... I'm going to wink and nod to entanglement where it figures in, but I'm not going to go into detail. I'm going to save that. So just put a placeholder. Say when I, when I say the word entanglement, I want you to ring a little mental bell and say, okay, I may not fully understand how that works. We're going to get there later.

I would have preferred it the other way around, but this is life. And I don't want to go into detail because who would want to spoil an entire episode on Entanglement? I've got to have some reason to bring you guys back every other week. I need some sort of hook where you'll just think you're done. We're never done with complete knowledge of time and space, but I have to convince you every single time. I need to talk about entanglement because I need to talk about degeneracy pressure. I've mentioned and I've spoken about degeneracy pressure before. We've met it. We've met it in white dwarves. We've met it in magnetars and neutron stars. We met it recently in metallic hydrogen. And while I've talked about it at a very surface level, we never got into the real nitty gritty dirt under your fingernails, hearty meal satisfaction detail that I think you deserve. So I'm going to start there with degeneracy pressure. Entanglement works in in a very cool way. And then we'll go on to quark stars.

So to get this story started, before we build up to quirk stars, whatever the heck a quirk is, I want you to think of two particles. Completely, 100% identical twins. You cannot tell them apart. They look the same. They talk the same. They smell the same. They act the same. They are identical. You can't tell. To help yourself out... To keep them distinguished, these two identical twins, you're going to give them labels, just little name tags. Nothing associated with the property of the particle itself, because there's twins, you can't tell them apart, but just totally random and artificial name tags that you're going to stick on them. Say one you're going to call Adrian, and the other you're going to call Enrico. Just two names out of a hat. Now, these two particles, because they're identical, they're a little bit mischievous. They like to play games. Sometimes when you're not looking, they'll swap name tags. And this frustrates you to no end because you would like to keep track of which one is Adrian and which one is Enrico.

And every time you turn around, they get together and they swap name tags. And then you're not exactly 100% sure if you're looking at Adrian or you're looking at Enrico. So to mitigate this, to try to stop them, you're going to keep them separate. You're going to keep them in separate rooms. If they're in the same room, they're going to be on opposite side of the dinner table. They're not going to get close to each other. And as long as you can keep them apart, you can keep track of each individual particle. As it moves around, they might have their own trajectories and positions and velocities, whatever particles do when they're up to no good. You're going to keep track of them. And as long as they're separated, you are confident that Adrian is Adrian and Enrico is Enrico. But if that situation happens, let's say, you know, you get a little lazy, something comes up at work, you're home late, whatever. And you've come home to find Enrico and Adrian very close to each other in the same room.

How do you know that? They've switched labels or not. How do you know which particle you're looking at? This situation, the definition of close might mean they're entangled. That if they're in an entangled state, they have an opportunity to switch labels. And you're not exactly sure which label goes on which particle. That happens in the entangled state. So how do you know you don't? They're identical. That's like the definition of identical. You can't tell them apart without these artificial labels. So that's the definition of identical. And when they're close, not only are they identical, they're indistinguishable. That's a very, very subtle thing, the difference between identical and indistinguishable, but we need to make that distinction. When they're far apart, they're identical, but you can tell which is which because you know there's no chance that they've swapped labels. Once they have the opportunity to swap labels, they become indistinguishable. You really don't know. Which one is Adrian? Which one is Enrico? Let's say these particles are like electrons or protons, even atoms.

Particles, tiny little particles, are ruled by quantum mechanics. And in quantum mechanics, we need to summarize every property of a particle so that we can keep track of how it might evolve when it's moving around or interacting or doing physics stuff. The summary, the list of everything associated with a particle, The label you might give it isn't necessarily a name, but it's called a state. When I say the state of a particle, I mean a list of its mass, its charge, its spin, its energy level. Everything that I can associate with that particle goes in a big list, and I call that list a state. When there are two identical particles next to each other in a tiny box, we have a little bit of a mathematical conundrum. When they are close to each other, when they are indistinguishable, when they can swap labels at any time, they are in an entangled state. And in quantum mechanics, it's not just good enough to describe each individual particle separately because they're entangled, because they're a little bit mixed together because I don't know which one I'm talking to at any given moment.

I need to create, I need to write a state. I really need to write a mathematical description of the combined states of the two particles. Come on. So one mathematical description that describes both particles simultaneously in the box. If I want to do any kind of physics and quantum mechanics, that's what I have to do. Now, it turns out that that mathematical description that we use to describe those combined particles can only take one of two possible forms. There's only two ways we can write down a mathematical description in quantum mechanics to describe these two indistinguishable particles. In one form of the equations, one way of writing the equations down of this combined indistinguishable state, when the two particles swap places, nothing changes. In the other form, the way the mathematics are written, the actual equations that we would write down, when the two particles swap places, a minus sign pops out in front. In the first case where you swap particle positions, when they swap labels or swap positions and nothing changes, that's called symmetric.

And if they swap places and in the mathematics and a minus sign pops up, it's called anti-symmetric. Just to be clear, that minus sign that pops up in the mathematics, it's not like a minus sign appears in space or the particles have negative charge or negative mass or negative anything. It's a minus sign in the mathematics and the mathematics only. It appears in the math. It doesn't appear like to your eyeballs. And I hope that makes sense. What I'm trying to get across is we need to separate the physics of what's happening, the physical reality of these two particles being close to each other, with our mathematical description of it. And in the mathematical description of two particles to a set of twins in a box where we can't tell them apart, if they swap positions... If Adrian is on the left and Enrico is on the right, and then I turn around and Enrico is on the left and Adrian is on the right, if the math that I use to describe their state doesn't change, then they're symmetric. And if it does change, if a little minus sign pops out, it's anti-symmetric.

Now, it turns out that particles in the universe must either be of the first kind, symmetric, or the second kind, anti-symmetric. If they're the first kind, if they're a certain kind of particle and they just happen to be symmetric, when they swap places, nothing changes. And if it happens to be an anti-symmetric kind of particle, when they swap places, the mathematics gets an extra minus sign. What does this have to do with anything? Don't worry, we're almost there. You remember particle spin? If not, check out the old episode. It's a great one. It's a fundamental property of particles. Like if you have a particle, it has mass, it has charge. It also has this property that we'll just call spin, even though that's kind of a horrible name. Different particles have different masses, they have different charges, and they have different spins. Some particles have spin that we call half or three halves or five halves. Other kinds of particles have spins of zero or one or two. You can either have a spin of a half or one or one half or two, you know, on and on and on.

It turns out that if you happen to be spin zero or spin one or spin two, then you are a symmetric particle. That means if you swap places with one of your friends, nothing changes in the mathematics. And it turns out if you're spin half or three halves or five halves, you're the second kind. You're anti-symmetric. That means if you swap places with one of your friends, a little minus sign pops out in the mathematics. Where'd that come from? Who asked for that? It is just how the universe kind of works. We give a name. to particles that are symmetric, that are spin 0, 1, 2, or 3. We call these bosons. And the half-spin, the half, three-halves, five-half-halves that are antispectric, we call them fermions. So here we go. This is the big bow to put on this particle present. If Adrian and Enrico, you've put these little labels on these two particles, And you want to know, like, hey, I wonder if they're symmetric or antisymmetric. I wonder if they're fermions or they're bosons. Well, you put their little label on and you let them swap places.

If nothing changes, then they must be bosons. They must be spin one or spin two or spin zero. And if a minus sign pops up in the mathematics, they must be fermions. They must have spin half, three halves, five halves. Okay, so what? Well, here's the juicy bit. The juicy bit is you need to go to patreon.com slash pmsutter to learn how you can support this show. Your contributions, your monthly contributions, whether it's a dollar or five dollars, any amount of dollars, even fractions of a dollar, half dollar or whole dollar, it doesn't matter. Fermion dollar, boson dollar, it doesn't matter. You can keep this show going. I greatly appreciate it. It's your contributions that keep this show alive. Go to patreon.com slash pmsutter. Now here's the real juicy bit. Let's say, let's say, go ahead and say Adrian and Enrico are fermions. They're half spin. They're antisymmetric. They're fermions. And they have the exact same state. They really are identical and indistinguishable. They have the same charge.

They have the same spin. They have the same mass. They have the same energy value. Everything about these two particles is identical. Adrian and Enrico. And they're fermions. If they swap places... If I put them in a little box and they flip around, by the quantum rules of fermions, a little minus sign pops out in the mathematics that describes their combined state. But for us, just looking at it with our eyeballs... The two situations must be identical because the particles are twins. Enrico on the left and Adrian on the right looks exactly the same as Adrian on the left and Enrico on the right. Because that's by definition. They're identical. There's absolutely no way I can tell one particle from the other. Nothing at all distinguishes them. So by just looking at it, if I flip them around, that situation looks exactly the same. But... In the mathematics, it's not the same. A little minus sign pops out. Something is wrong. Something doesn't add up. How can a state or a combination of states, a mathematical description, be a negative of itself? In one view...

The particles flipped around look exactly the same. I don't know which one's Adrian, which one's Rico. But the mathematics says, no, it's totally different. There's a minus sign. Like the mathematical description is off. The only number that is equal to its own negative is zero. The only way to resolve this situation where from one point of view, the particles are absolutely identical, have the exact same state. But from the mathematical point of view, no, there's something different happens when they swap places. Is that this situation can't happen. that Adrian and Enrico can't. It's impossible for them to have the same state. If these particles are fermions, if they have spin half, then there are rules that apply to them. This particular rule is called the Pauli Exclusion Principle, named after the guy who figured it out, Wolfgang Pauli. Two fermions cannot occupy the exact same state because the mathematics won't allow it. The rules of the universe... cast down upon us have said, hey, if you have spin half or three halves or five halves, you are not allowed to have the exact same state, the same charge, the same mass, the same energy level, everything the same as any of your friends.

Just not allowed. something about Adrian and Rico have to be different. They're not allowed to be indistinguishable. They're not allowed to be identical. They're not allowed to have the exact same state. They're just not allowed because a little minus sign. You don't always blame a minus sign. A minus sign pops up in the mathematics. They are not allowed to have the same state. Something has to be different. Maybe one is spin up and the other is spin down. Maybe they have to sit at different energy levels. It doesn't matter what's different about them. Something's got to give. Something has to be different. They cannot be the same. They cannot have the exact same state. To get to this point where no two fermions can share the same state. I said a lot. It turns out. It turns out this. It turns out that. It just so happens that this is the way the universe works. When we were first uncovering quantum mechanics in the early 20th century, these rules just appeared to be basic facts about the way the universe works.

We discovered them through experimentation, but they were just kind of shoehorned into quantum mechanics. Like, hey, we'll just make a list of everything that nature is telling us. We have no idea what's going on. But hey, we're going to call these kind of particles fermions. They can't share the same state. They're antisymmetric, et cetera, et cetera. We're just going to write it down. Back in the day, you could win a Nobel Prize for just doing that. Those, man, those were the good old days where you could just list things that you don't understand and not only write a paper, you could get the highest honor in physics. But, you know, that ship has sailed. You got to do harder stuff nowadays. The cool thing is that we do have a source for understanding where these fundamental rules come from. They don't just pop out out of nowhere. It's when you combine special relativity with quantum mechanics, you can develop some theorems. That's right, theorems, not theories. These are theorems. These are mathematical proofs.

that connect the spin of a particle to the properties of its symmetry, whether it's symmetric or anti-symmetric, whether it gets to share the same state with one of its friends or whether it doesn't. That comes from a very cool connection, very deep, a very mathematical connection happening. It's a rule of special relativity. It turns out it has something to do with special relativity applied to the case of quantum mechanical systems give you these things. That's kind of hard to talk about, so I'm just going to stick with it there. If you'd like to learn more about that very deep and fundamental connection, feel free to ask. So what does this give us? We have fermions like electrons, protons, neutrons, and quarks that can't occupy the same state. What? Who cares? Who cares? Well, atoms care. This is how you can get electrons in different energy levels orbiting a nucleus, surrounding a nucleus, I should say, which gives you, I don't know, all of chemistry. It's due to these rules, due to these symmetric rules, the exclusion principle.

This gives you, let's say, the behavior of metals. Kind of important. Gives you metallic hydrogen, which we talked about. And it gives you degenerate stars. Degenerate stars are stars, dead stars, that are held up by the rules of quantum mechanics itself. Most stars are not supported by degeneracy pressure. They're supported by just normal pressure. They're just super hot. They're a gas. And gravity wants to squeeze it in, but because it's so hot, the gas says, no, I resist you. I'm going to try to blow up in those two forces, the explosive outward expansion and the contraction of gravity, balance each other out, and boom, you get a star. If you take a gas of fermion, say you take a whole bunch of electrons. And cool it down. Get rid of its temperature. Ice it down. What if you brought it all the way down to absolute zero? Which you can't, but let's play pretend. You would expect, you would expect, if you took this cloud of electrons and cooled it down to absolute zero, it would scrunch way tight together.

But... You will be surprised. There is still a source of pressure because not all electrons can cram into the zero temperature, zero energy state. Only one electron will reach the zero temperature, zero energy state. And once it's there, it's like, hey, guys, I'm full. I already took it. It's mine. I'm in the ground state. I'm in the low energy state at zero degrees temperature. And none of you can come in. All other electrons, because they can't share that state, they're not allowed in. There's only one of them. They have to go into higher energy levels. So they will still have energy. A gas of fermions at absolute zero will still have energy because of this exclusion principle. And that energy translates into a degeneracy pressure. You can cool this ball of electrons, this ball of fermions down to absolute zero, and you can try squeezing on them and they'll resist because they've got nowhere to go. They're like, no, I can't go down to the ground and say, I don't care how hard you're pushing me, man.

I cannot go down there. It's already full. Can't you see? I'm going to have a certain amount of energy. like I mentioned in the episode with metallic hydrogen, there's another way to understand this or another, another way to approach this, I should say. And that's through the Heisenberg uncertainty principle where you cannot measure the position and the velocity of a particle with equal precision. You have to give up something. You can imagine, you can look at it through this lens, where you're trying to squeeze down electrons into a very, very, very, very, very tiny state. You know, small, compact volume. Say, no, I want you to go in this tiny little box, little electron. But the more you pin down its position, the more you know about its position, it means the less you know about its momentum, the less you know about its speed. So if you try to cram down an electron into a very tiny box, it's going to vibrate like crazy. It's going to have really, really high ridiculous velocity due to the fact that you're trying to cram down its position.

So it's going to bounce around a lot. It's going to fight you. It's going to be a pressure. It's going to be hard to do. When electrons support a star against collapse, we call it a white dwarf. And that's about the mass of the sun compressed into, say, the size of the Earth. This degeneracy pressure of a white dwarf was first worked out. It was discovered by supermanian Chandrasekhar, who is an awesome guy in physics and astronomy history. An amazing story. I'd love to tell this story sometime. Just ask. And if you can't write it down, just say, hey, that Indian physicist that figured out white dwarfs, happy to go into it. Chandrasekhar figured out how a star could support itself with degeneracy pressure, basically discovered white dwarfs before we knew what a white dwarf was, but figured out that there is a limit when it comes to electrons. Degeneracy pressure is super strong, but it can be overwhelmed. You can force the electrons into a different state. Chandrasekhar didn't really know what would happen if you took a white dwarf and overwhelmed it.

If it has a mass greater than 40% more than the mass of the sun, gravity will be too strong. It will overwhelm the degeneracy pressure. He wasn't exactly sure what would happen. We do know what happens now. When you take something like a white dwarf and squeeze on it so much that the degeneracy pressure of electrons overwhelm it. What we realize can happen is that you can take a proton, shove an electron inside of it, and turn it into a neutron. And so if you have a star made of a mixture, a nice healthy mixture, protons, neutrons, and electrons, if the gravity gets too strong, then the electrons, they're still fighting with degeneracy pressure. But due to the increased gravity, they'll find themselves being shoved into protons instead, turning them into neutrons. And you basically can convert an entire star into a giant ball of neutrons, just neutrons. Once you have that, the neutrons can support themselves again against further collapse by degeneracy pressure because neutrons are fermions.

They're in the same camp. They have the exact same quantum rules applied to them. So you can overwhelm electron degeneracy pressure and boom, get a neutron star. The neutrons are much more massive than the electrons, so they can be squeezed even tighter together. That's why you get these amazing creatures called neutron stars and magnetars, where you take two or three suns worth of material and cram it down into the size of a city or a neighborhood. That's how impressive these things are. But neutron stars, neutron degeneracy pressure, it can be overwhelming too. We're not exactly sure how massive a neutron star can get before the degeneracy pressure is overwhelmed in that case. Somewhere around two or three times the mass of the sun. It's much harder to figure out. Much, much, much, much harder to figure out because nuclear physics is kind of hard. And also gravity is strong enough inside of a neutron star that we need to understand general relativity. Basically, we don't fully understand what's going on inside neutron stars.

It's just super hard. And unless we crack one open, it's going to be kind of hard to figure it out observationally. We can only see them from the outside. We don't have any here on Earth. Kind of a sticky problem. So it's a good question to ask. Okay, if I overwhelm electron degeneracy pressure, I get a neutron star. What happens when I overwhelm neutron degeneracy pressure? Right now, we don't think there's any lower level. There's no other sources of pressure support. There's no other crazy exotic physics. Gravity just crushes everything to infinity and we get a black hole. Of course, like I talked about at length when it came to black holes, we know that the singularity doesn't exist, but we do know that black holes, the astrophysical objects exist. Black holes are there. We know that something happens in the singularity to prevent the formation of an infinite point of density because that's not a thing. But is there anything in between? Is there anything in between a neutron star and a black hole? Well, if you crack open an atom under high pressure, you get a bunch of electrons, you get a white dwarf.

Crack open that, you get, you know, push it down even further, you get converted into a neutron star. If you crack open neutrons under high pressure, you get a bunch of quarks. Yeah, quarks. Welcome back to the wonderful world of particle physics jargon, which I'm sure you've missed here on Ask a Spaceman. But you keep asking questions, and we need to dip our toes in the particle physics world with all its wonderful and Byzantine and horrible, I lied about the wonderful part, jargon that comes with particle physics. So it's really your fault that I'm here, and I'm totally blaming you. Very super quick version is electrons are just electrons. Protons and neutrons, however, are actually bags of smaller particles that we call quarks. Each proton and neutron is made up of three quarks all glued together with the strong force. There are six kinds of quarks called up, down, top, bottom, strange, and charm. If you have up, up, down mixed together, you get a proton. If you have down, down, up, you get a neutron.

You get various other combinations. You get various other kinds of heavy particles. One of the things that makes studying these so difficult is that quarks have an interesting property to be explored if you so desire. That they are confined to form groups like protons and neutrons. They can't exist on their own. You'll never see just one quark by itself. It will only ever be bound together with other quarks to make heavier particles. So no matter how much they'd like to be free and isolated, they'd always be forced to be in pairs or triplets or higher groups. So to get to the question, do quark stars exist? Is it possible to make a quark star, something between a neutron star and a black hole, that's supported by quark degeneracy pressure? Well, in order to figure out, we need to play some games of physics. In the game of physics, We follow the mathematics to make predictions and figure out what the observable consequences might be. We go hunting in the universe to look for a particular signature for evidence of a particular mathematical theory.

Or you can play it in reverse. You can find stuff in the universe that we can't explain and you can cook up an explanation for it. So let's follow game number one. What do we predict? If we're going to pretend that quark stars exist, what might they look like? Well, it's kind of hard to say. Neutron stars are hard to understand, but at least they're neutrons. I mean, come on, everybody has a neutron. Quarks are a whole new level of difficulty. We can't study individual ones in the lab, which sucks. And the math is super hard, which really sucks. We do know that to pop out some quarks out of a neutron, it requires incredible pressures and temperatures. And that if you tried to make a star out of, say, a mixture of the normal, familiar up-and-down quarks, like the ones a neutron is made out of, it would be very unstable. If it was exposed to space, it would just boil away, basically. But there are some possible pathways that if you're trying to scrunch down a neutron star, and it starts popping out quarks all over the place, and they start combining together in interesting combinations, that some of them might be converted into strange quarks, this...

one branch of the quark family tree and they might be a little bit more well-behaved like you can maybe kind of sort of construct a large object like a star and expose it to the vacuum of space and it might survive if it is possible if nature is even capable of manufacturing quark stars it must be very rare because there's only a thin window between a neutron star in an all-out black hole all-out gravitational collapse catastrophe. There's a transition from white dwarfs to neutron stars. And right now we think there's just the smooth transition. Like if you're too strong for a neutron star, boom, you're going to make black holes. We know neutron stars exist and we know black holes, the astrophysical objects exist. There's like not a lot of wiggle room to make a quark star. Well, what about a different approach? Maybe you could stuff a quark star core inside of a neutron star shell like an M&M. Except it's a Q&N. And it might be okay. It might live. Perhaps. Maybe all neutron stars really have quark cores.

And that is so hard to say. due to the extreme conditions in the cores. Well, then that's fine. We just need to rename it. That's just a renaming exercise. Instead of neutron stars, they're really quark neutron stars, and just call it a day. That's a big fat maybe, that maybe neutron stars, the cores, are so exotic that they really have quark cores. Say that 10 times fast, I dare you. That's super hypothetical, though, because like I've mentioned, we don't fully understand the material properties of quarks. We don't understand the strong nuclear force very, very well. It's hideously complex. We don't understand the interiors of neutron stars. Full stop. We don't know what's going on on the inside. So maybe they have quark cores. Maybe they don't. Either way, if they exist, whether quark stars exist inside of neutron stars or as their own independent object, it's very hard to tell a quark star from a neutron star. From the outside, they're both dense. They're both small. They're both super hot.

It's hard to tell if you just look at a neutron star or something weirder. So what about game number two? Is there anything out there in the universe that we can't explain that's just begging for an explanation? And wouldn't you know it, quark stars are just going to fit the bill. Well, there is a gap, right? There is a gap between the maximum neutron star mass, about two-ish times the mass of the sun, and the smallest black hole that we've ever seen, about three, a little over three times the mass of the sun. Maybe there's a nice snug little fit for quark stars right there. A little bit, I'll put it right there. A little bit, no one will even notice. Maybe. But it could be an observational bias, like it's easier to find big black holes. Maybe there are two, two and a half solar mass black holes floating around out there. They're just hard to spot. Possibly sometimes we see some explosions that look like supernova or regular nova, but seem a little off kilter. You know, the elements seem wrong.

The maximum brightness is a little bit off. The time it takes to cool down is a little bit off. Maybe it's what's called a quark nova. Yeah. We might be witnessing a transition from a neutron star to a quark star, and that releases a bunch of energy? Maybe, or could we just don't understand the finer details of supernovas? There are some neutron stars that might be a little bit too small and a little too dense to fit our current understanding of the strong force and how neutrons behave under high pressures. That could fit the bill as a quark star. Like, oh yeah, that's a candidate. Well, it could be due to the fact that we don't really understand, you know, neutron stars. So there's a lot of mystery around quark stars. Theoretically, it's hard to make progress because, you know, we don't understand quark physics and neutron physics, strong force physics very, very well. And it's hard to support observationally because all the candidates that you could point to could also reasonably be just other things.

So overall, do quark stars exist? I'm going to give it a weak maybe. A week, maybe. It's possible it hasn't been ruled out. There's no equation that's popped up saying, nope, nope, not in this universe, fellas. And there aren't a lot of observational hooks. A lot of things we can point to and say, you know what, that's really good Canada for a core star. We can't do that. We certainly don't understand many things about our universe. That's a given. But none of the mysteries really fit the bill for what a quark star would look like. There doesn't seem to be a lot of room for them. So they may end up as theoretical possibilities, but it's just that nature doesn't manufacture them. And you know what? That's just how physics works. Thank you so much for listening. And yes, I did change up my intros. Let me know how you like it. I can go back to the old way. I mean, you're the audience. You're in the driver's seat. If you like the old way of opening the show, let me know. If you like the new way of me just doing cold opens, going right into it, let me know too.

Go to AskASpaceman.com. There's submission form so you can tell me what you think. Thank you so much to AtWigabo. Not exactly sure how to say that, but you know who you are. On Twitter, for asking what's a quark star and its properties. At Shamanic Pistol. Also on Twitter, what's up with quark stars and strange matter. And Larry B. on YouTube asking, do quark stars exist? Big thanks to my top Patreon contributors this month. Justin G., Matthew K., Kevin O., Justin R., Chrissy, and Helga B. It is your contributions that keep this show on the air. Go to patreon.com slash pmstar to learn more. And before I go... Before I go, this is very cool. There is a new AstroTour available to northern Chile, to the Atacama Desert, the driest, some of the darkest skies in the world. I'm leading a very small select group. It's going to be a small tour, just no more than a couple dozen people. You need to go to astrotours.co, astrotours.co. to sign up, make your deposit for the Atacama Desert. We'll figure out the rest of the money later.

It's going to be amazing. It's like every night dedicated to some seriously hardcore stargazing. You need to go. You also need to go to spaceradioshow.com. That show is live and well, and you get to talk to me on the air every single week. It is just so much fun. There's a lot of cool stuff going on. Go to AskASpaceman.com. You'll see links for everything else. If you can't make a Patreon donation, I really appreciate telling your friends about it, telling people about mentioning it on social media, going to iTunes, giving a review, preferably a four or five star review. I'd really appreciate that. Whatever you can do to help keep this show going and growing, I am in your debt. And I try to service that debt by telling you about all the crazy stuff in the universe. Thank you so much. And I will see you next time. Keep those questions coming to hashtag Ask a Spaceman on Twitter and Facebook. Follow me on Twitter and Facebook. My name is at Paul Matt Sutter. Going to AskASpaceman.com. And I'll see you next time for more complete knowledge of time and space.

AaS! 69: What makes a blazar blaze so brightly?

What powers a quasar? Just how strong is a blazar? What’s the connection to giant black holes?  I discuss these questions and more in today’s Ask a Spaceman!

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EPISODE TRANSCRIPTION (AUTO-GENERATED)

One of my favorite parts of observing the night sky, of going sky watching, is the depth. That you're not just looking at things in our own atmosphere or even our own solar system. These objects there sending their light to you are thousands, tens of thousands of light years away. These incredibly, almost impossibly distant objects. And you get to see them. So there's this incredible richness and depth to the night sky that's almost overpowering, to me at least, sense of depth. And the things you look at, if you look in any one particular direction in the night sky, you are looking at something incredible. For example... If you look in the direction of the constellation Sagittarius, you're looking in the direction of the center of our own Milky Way galaxy. In the center of the Milky Way is a dense cluster, a bulge of stars, of nebula, of gas. It's the bustling downtown as viewed from way out here where our solar system is out here in the suburbs. And it's a beautiful, if you get a chance to see the center of the Milky Way galaxy through binoculars or a telescope, it's just flooded with stars.

But deep in the center of the Milky Way galaxy, there is a black heart. black hole four million times more massive than the Sun the closest example that we have of a class of giant black holes called supermassive appropriately named supermassive black holes this one particular black hole has a name Sagittarius a star and This object, like I said, four million times more massive than the sun, is a monster. It's a beast. But it's well hidden. It's obscured by the countless stars surrounding it and the clouds of gas and dust enveloping it. And right now, it's slumbering. It's sleeping. It's not active. It's sitting there quietly. But material falls onto that black hole, gets caught up in its gravity and funneled into it, crosses through the event horizon. As it does so, as that material compresses and falls onto that black hole, it screams. And the first person to notice this screaming was Carl Jansky, one of the founders of radio astronomy. He saw this in the 1930s when he first developed a steerable radio array so he could turn it around and he could use it to pinpoint positions on the sky.

And this particular radio array was sensitive to a range of frequencies. And it turns out those frequencies were loudest. The loudest thing emitting those frequencies were thunderstorms. And he was able to pick out nearby thunderstorms. He was able to pick out very distant thunderstorms. But once he isolated those sources, there was a faint hiss. a signal that wasn't connected to anything he could find in the atmosphere. In fact, it wasn't connected to anything on Earth. And at first he thought maybe it was the sun or maybe Jupiter, but it wasn't connected to those either. After months of observation, Carl Jansky found figured out that this strange radio signal, this background hiss, was strongest from the constellation Sagittarius, from the center of the Milky Way galaxy. That result, while interesting, was relatively ignored. He couldn't get his bosses, who were paying for all this work, for him to do continued astronomical research. So he went on to do other things. And it wasn't until decades later that...

Radio astronomy got into serious high gear and began really mapping the skies, doing surveys of the sky in the radio spectrum. And these later radio astronomers found hundreds of bright radio sources. And at first, it was a total mystery. These were not connected to anything that they could obviously see. It wasn't like the Andromeda Galaxy or a globular cluster or comets or planets. It was just all over the sky, appeared to be outside the Milky Way galaxy. Eventually, after a lot of dedicated work and some lucky coincidences, one of the first radio sources to be detected, and one of the loudest ever to be detected, for the curious the name of this source is 3C273, after enough work, this radio source was matched to an optical image. And this matching didn't solve any problems. It raised like a thousand questions because this optical image looked like a star. It was incredibly bright and incredibly small, just exactly like you'd See a star. If you look at a star through a telescope, it's small and it's bright.

If you look at something else like a galaxy, it's dim and diffuse because it's so far away, but it's so big. You look at a nebula, it's dim and diffuse because it's not very bright and it's very big. You look at a star, it's small and bright. Whatever this thing was, this object 3C273 was emitting serious radio emission and it looked like a star. And it gets worse. Eventually, we're able to take a spectrum of it, get its elemental fingerprints to see what it's made of. And all the usual suspects were there. Hydrogen, helium, carbon, oxygen, all the usual elements that you typically associate with stuff in outer space. But it was all wrong for a star. It had all the right elements in the right places, but everything was shifted to the red. Everything was moved over. And the only way to make sense of that, that this is a typical spectrum that we expect, that we associate with things like stars or nebulas or galaxies, but incredibly redshifted, is for it to be incredibly far away. Specifically, 2.4 billion light years away.

This one source, 3C273. 2.4 billion light years away. For some perspective, the width of the Milky Way galaxy is 100,000 light years. 100,000, this thing is 2.4 billion light years away. And it's so bright that it looks like a star. It's so intense. It's so intense that if you were to take this object, whatever this object is, 3C273, and put it, say, I don't know, a few dozen light years away, two or three dozen light years away, within range of some familiar nighttime stars, At that distance, this object would be brighter than the sun. That's how bright it is. Four trillion times more luminous than our sun. We didn't really know what to make of these at the time. It was a radio source, a source of radios, that kind of sort of looked like a star, hence the name Quasi-Stellar Radio Source. Shortened to Quasar because who couldn't resist coining an awesome name like that? I know I couldn't. If I see Quasi-Stellar Radio Source, I would want to shorten that to something cool like Quasar. Hence the name Quasar was born.

Over time, we discovered more quasars. It turns out most of these, if not all of these bright radio sources, were indeed quasars. Very, very distant. The closest were hundreds of millions of light years away. And most were incredibly far away, billions of light years away. The source of this emission of both the radio and the light is small. It has to be small because we would observe changes in the brightness over time. And let's say you make one observation, you measure the brightness at one time, and then say a year later you go back and look at it again, and its brightness has changed. That means over the course of a year, it's changed its brightness, which means the object must be smaller than one light year across. Otherwise, there'd be no way for everyone in the object to get all coordinated and communicate with each other and say, hey, everybody, we're going to lower our brightness. Make sure you set your clocks so we can all do it in time. Because of the speed of light, you have to be smaller than one light year across so that over the course of one year, you could change your brightness.

Well, we see changes in these objects over the course of a week. That means whatever this object is, whatever these quasars are, have to be smaller than a light week across, which is, I don't know, that's not much bigger than a solar system. which is not large. Considering this thing is four trillion times brighter than the sun, that's a small thing. What could these monsters be? The second side of the coin, they need to be small. The second thing is they need to be massive. to power the raw intensities that we observe. Something like a backyard star or a nebula doesn't have enough gravitational potential energy. It doesn't have enough oomph to drive something like that. It has to be massive. It has to be big just because of the raw energetic output that we're observing. So it has to be small, but it has to be massive. What could these quasars be? And that's when a big leap was made in about the 1970s because we have the case of Sagittarius A star, the giant black hole in the center of the Milky Way galaxy.

This giant black hole is emitting strong radio emission. Not the black hole itself, but the material falling into the black hole is emitting strong radios. Obviously not as strong as one of these quasars, but still pretty impressive. Loud enough for Carl Jansky to notice it in the 1930s. So if we have a giant black hole and it's emitting radio waves, and we see something super far away that is insanely bright and very small... Maybe quasars are powered by giant black holes. It's estimated. It's estimated that 3C273, the prototypical quasar, the first quasar, is powered by a black hole with a mass 800 million times greater than the sun. And it gets bigger from that. We see black holes 10 billion times more massive than the sun. True monsters sitting at the center of these galaxies. And now it's relatively commonplace. It's realized that almost every galaxy in our universe hosts a giant black hole in its core. We're not alone. So what's going on? How does a black hole emit bright and loud radiation? Well, you need two basic ingredients.

You need a giant black hole and you need a blob of gas. Pretty easy recipe. Gravity does all the work. The black hole's sitting there doing its thing, being massive, hanging out, not bothering anybody. The blob of gas is attracted to it gravitationally because that's what gravity does. The material falls in. If you take an enormous amount of material, like a giant blob of gas, and send it screaming towards a black hole, it's going to compress because everybody's trying to cram in through the relatively narrow area of the event horizon, the surface of the black hole, which is relatively small compared to the size of the stuff that's falling into it. So if you take a bunch of stuff and you squeeze it down, what's going to happen? It's going to heat up. That's what gases do. It's like a bunch of people crowding into a crammed subway car. It's going to get hot. It's going to get sweaty. It's going to get awkward. That's just the way things are. The material falls into a black hole. As it falls in, it gets hotter and hotter and hotter, releases all that gravitational potential energy.

Due to friction, it gets converted into heat and it glows. It glows. And it's hard to put a superlative on the amount of brightness of this gas falling into a supermassive black hole. To give you a picture, to give you a picture, you know supernovas, right? Good old supernovas, really, really bright. A single supernova detonation, the death of a massive star, can outshine an entire galaxy for a few weeks. An entire galaxy, that's hundreds of millions of stars, can be outshone by a single supernova detonation for a few weeks. When supernova occur in our own galaxy and the conditions are just right, we can see them during the day. The last time this happened was about 500 years ago. We can see supernova during the day. That's crazy, crazy intense bright. outshining a galaxy for a couple weeks. A quasar. A quasar, material falling into a black hole, can outshine tens of thousands of galaxies for millions of years. I'll say it again. I'll say it again. It deserves being said again. A quasar can outshine tens of thousands of galaxies for millions of years.

They are the single most luminous objects in the universe next to the cosmic microwave background itself. Next to the afterglow of the Big Bang itself. They are the most luminous objects. By far the most powerful engines. The energies released in a quasar rival the energies released in galaxy collisions. That is a lot of energy. That is raw output. Speaking of galaxy mergers, that's how we think quasars might ignite. How does so much gas get to a center of a galaxy? It doesn't happen a lot, but when two galaxies crash into each other, or more accurately, as we've explored, when the swarms of stars merge together, the black holes that each galaxy carries find each other in the center, orbit around each other, decay, and then merge, and you get a single, much, much more massive black hole. Wow. And lots of gas gets tossed around. Insert your own crude joke here if you want. The gas swirls into the center of the galaxy, settles into the center of the newly merged galaxy, falls into the black hole, and the show begins.

This relationship, though, is tough to tease out because it's not like we get to see this happen in real time. We only have before, during, and after snapshots. And so we have to rely on statistics to figure it out. But that seems to be it. It seems to be that when galaxies merge, we get an ignition of a quasar. And this might explain why the quasars are so far away. Farther away means you're looking at earlier and earlier epochs in the universe. And in the more distant universe, which equals the more earlier universe, mergers were more common because the universe was smaller and structure formation was really getting going. Galaxies were still building up. And as they build up, they would have a blast of quasar activity. And then the quasar would settle down. And then, oh, no, here comes another galaxy. And then a new round of quasar. Most modern day galaxies are quiet now. Structure formation has ceased about 5 billion years ago. Galaxies aren't growing the way they used to. They don't make them like they used to.

And so there aren't as many quasars. In fact, we don't see any nearby quasars. We have to go out hundreds of millions of light years before we see our first quasar. galaxies though are do still occasionally merge the andromeda and milky way are on the path to merger they will merge in about five billion years will that ignite a new quasar in our newly merged black hole most likely yes but that's not for five billion years from now but so far i've been talking about quasars what the heck is a blazar That's because if you want answers, you need to pay. That's right. You need to go to patreon.com slash pmsutter to learn how you can contribute to keep this show going. I truly appreciate it. It's your contributions that keep all my education and outreach activities going. I can't thank you enough. And if you want to unlock the rest of this episode, you need to make a donation right now. Of course, I'm just kidding. I'm just going to keep talking. The difference between quasars and blazars is that there's more to the story of just junk falling into a giant black hole.

And the story involves magnetic fields. Your favorite. You knew it. You knew they would come up, didn't you? That's right. Magnetic fields are here again to power quasars and blazars. Here's what happens. Here's what happens. This is so cool. You take a giant blob of gas. It's going to fall into the black hole. It's going to accrete onto the surface of the black hole. As that giant blob of gas falls in, it compresses, heats up, glows. We see it. Boom. Quasar. But there's more. If that giant blob of gas has just a little bit of spin, which it will just by random chance, then as it compresses, because of conservation of angular momentum, it's going to spin faster and faster and faster and faster. And as it spins, as it compresses, it's going to turn from a blob into a disk. Nature doesn't make a lot of shapes, right? Nature knows how to make blobs. Nature knows how to make balls. And nature knows how to make disks. And in this case, if you're spinning and you're compressing, you get a disk.

That's the same reason why the solar system is a disk. That's the same reason why the galaxy is a disk. That's why there are these accretion disks around these giant black holes. You have a swirling, whirling mass of high energy plasma swirling around a black hole, doing its thing. These are charged particles. They're gonna create electrical currents. Electrical currents are gonna generate magnetic fields. That disk contains a very strong magnetic field. And then dynamo actions kick in to amplify the magnetic fields to be much, much, much, much stronger than you would normally expect. This is the same kind of dynamo physics that happens in the Earth's core that gives us our magnetic field. The same kind of dynamo physics that happened in the sun that gives it its magnetic field. Now it's happening in these accretion disks around these giant black holes. These magnetic fields do something really cool. Relatively poorly understood because the physics is so complex here, but it still happens.

The magnetic fields twist and warp. They wrap themselves around the black hole. And due to their complex geometry, gas is responsive to that magnetic field. It will start following the lines of magnetic field. So most of the gas still falls through the event horizon into the black hole, never to be seen again. But some get caught on the magnetic field lines. Just like some of the solar wind gets caught on the magnetic field lines of the Earth and get funneled into the poles to create the aurora. This is like that in reverse. Some of the gas, as it's swirling into the black hole, gets caught up in the magnetic field lines. The magnetic field lines funnel them to the poles. Instead of going in, go out. and launch a jet, a relativistic jet, a jet of material traveling at close to the speed of light. The launching mechanism of the jet, like I said, is relatively poorly understood. It might be connected to the spin of the black hole itself. It might be tapping into that spin, extracting energy from the black hole.

It may be purely astrophysical, nothing to do with the black hole itself, just the physics of the accretion disk. We're not 100% sure, but we know it happens because we see it. These jets are enormous. And they're columnate. Columnate means the magnetic fields wrap around the jet like a straw, and they keep it nice and tight for tens of thousands of light years. That is bigger than a galaxy, folks. So this tiny little accretion disk, no bigger than, say, a solar system, as it collapses onto that black hole, gets spun up to a jet, and some of that jet leaves the entire galaxy. That's how powerful it is. Well outside the host galaxy before it finally dissipates. It does something else cool there. Once it goes beyond the galaxy, it can actually blow bubbles in the plasma surrounding galaxies. And I would love to talk about that in another show. So if you want to know about bubbles blown beyond galaxies, just ask the question. But this is crazy, crazy, crazy physics. Material jets jetting from the pole of a black hole getting shot out tens of thousands of light years at close to the speed of light.

Now, of course, most of these jets are going to point away from us. But every once in a while, the point right at us will be in the barrel of the blast. And then when that happens, we get an extra strong emission. We get a quasar that looks extra bright. One, because we have a giant ray of light pointed at us like a lighthouse. Because all this material traveling at close to the speed of light is hot, crazy hot. It's emitting radiation like there's no tomorrow. And it's blasting us full on in the face. So we're getting it. And there's a cool effect called relativistic beaming. If you take a light bulb, it's emitting equally in all directions. If you throw the light bulb at close to the speed of light, there's this relativistic effect where most of the radiation doesn't get emitted in all directions equally, but gets concentrated into a forward-facing cone. So at this material jetting away at close to the speed of light, if it's blasting us in the face, not only do we get the blast of the radiation, but all the other radiation that would have missed us, that would have gone off in all sorts of other directions, get focused onto us.

And because the gas is traveling at close to the speed of light, all the emitted radiation gets blue shifted into higher frequencies. So it's even more energetic and it's just nuts. And that's a blazar. A blazing quasar. A blazar. There's one blazar in particular that is powered by a black hole that is 40 billion times the mass of the sun. So think of the energy available with a system like that. 40 billion times the mass of the sun concentrated into a relatively small volume, like, I don't know, the orbit of Jupiter. That's a lot of energy available to do some interesting things. Add in magnetic fields, and you're good to go. gas falling in from a merger event so there's tons of gas available falls in compresses glows magnetic fields twist it up launch a jet and we see a blazar of course there's more to quasars and blazars they are two examples in a generic category of very bright and or loud galaxies When we do more detailed surveys in the radio or in the optical, we see all sorts of combinations.

Some galaxies have jets, some don't. Some are very loud in radio, some are quiet. Some are highly variable, some aren't. Some also spit out x-rays, some don't. All sorts of random names that seem like they've been pulled out of a hat to describe them, like Seifert or BL Lactase or Liners, etc., etc., etc., all grouped together under a common label called active galactic nuclei. Active because they're active, galactic because they come from galaxies, and nuclei because they come from the cores of those galaxies. Remember, this emission, this crazy hot emission, doesn't come from the whole galaxy itself, just the tiny little core. They're all powered by supermassive black holes. And the current guess is that it's the same physical scenario. It just depends on the direction we're seeing it, the angle we're seeing this object, or if it's in different parts of its life cycle. So maybe in some cases the jet is blasting us in the face and it's a blazar. Maybe it's not and it's just a quasar. Maybe the jet is very weak.

Maybe it shut off for some reason because there was a recent cooling event or heating event or vice versa. Maybe there's a disk of cloudy molecular gas surrounding the accretion disk that sometimes prevents us from seeing it very clearly. And so that gives it a different signature. That is in itself a completely different episode. on active galactic nuclei and all the varieties of active galactic nuclei, or AGN if you want to be cool. And of course, supermassive black holes are usually abbreviated SMBHs. Simbas? I don't know. Putting all the jargon together gives us the phrase of the day. Feel free to say this out loud with me. A blazar is a kind of quasar is a kind of AGN. Thank you so much for listening, especially the questions that led to today's show. We have at Ruth Kieran on Twitter asking, what is a blazar? At ChiliDog64 on Twitter, what is a quasar? TlockR on Facebook, supernova versus quasar, who wins? At KDA Welch on Twitter, is there a correlation between quasars and merging galaxies? Keith I on YouTube, how do black holes make jets? And Richard C on YouTube, how are all active galactic nuclei different? I'd also like to thank my Patreon contributors, my top ones this month, Justin G, Matthew K, Kevin O, Justin R, Chrissy, and Helgen B.

Thank you so much for your contributions. You too can contribute. Go to patreon.com slash pmsutter. Yes, I know I changed up the intro to this episode. Let me know if you like it. Thought I'd give it a shot. It's been about three years that Space, not Space Radio, that's the other show I do. It's been about three years since Ask a Spaceman has been on. So let me know. I thought I'd just change it up because sometimes change is nice. Speaking of Space Radio, you need to go to spaceradioshow.com. It is such a fun show. I do it every single week. It's live. You can call me. We have questions. We have discussions. Sometimes we even laugh a little. And you need to go to astrotouring.com. There are still some tickets available for the cruise, but it is booking up fast and we're launching new trips every single month. Uh, sneak preview. We're kind of going to Northern Chile in December of 2018 to the Atacama desert. And it's going to be super awesome. And you need to come with me, go to astro touring.com.

Thanks again. You can follow me on Twitter and Facebook. My name is at Paul, Matt Sutter. Keep those questions coming to hashtag ask a spaceman, or you can email, ask a spaceman at gmail.com or go, uh, go to ask a spaceman.com the website, uh, and go to iTunes to review. You know what to do. You know how this all works. Just please help me so that I can keep helping you. See you next time for more Complete Knowledge of Time and Space.

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!

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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!

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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.