Cosmic Queries – Astrochemistry with Kate the Chemist

How is chemistry different in space? Neil deGrasse Tyson and comedian Matt Kirshen explore cosmic chemistry, the periodic table, and more with Kate Biberdorf aka Kate the Chemist. Is the periodic table complete?

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  In the next episode of StarTalk, it's a Cosmic Queries All Chemicals Edition. My co-host, Matt Kirshen, together we meet and greet Kate the Chemist. This is Kate Biberdorf, and she tells us all kinds of things in response to our Patreon questions. For example, what is the only F-word she does not allow in her classroom? That's kind of interesting. And can we use the gaseous constituents of farts to decide whether life exists on another planet? That's kind of freaky, weird there. And did you know you can take an inert element and make a molecule out of it?

• 0:45Neil deGrasse Tyson?

  I didn't. I learned in this episode. So, check it out.

• 0:52Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide.

• 1:01Neil deGrasse Tyson?

  StarTalk begins right now.

• 1:05Neil deGrasse Tyson?

  This is StarTalk Cosmic Queries. This is a special chemicals edition because some of my best friends are made of chemicals. Of course, all of my best friends are made of chemicals. I got with me my co-host, Matt Kirshen. Matt, how you doing, man?

• 1:23Matt Kirshen?

  I'm good. I've just found out I'm made of chemicals. That's a little bit worrying, but, uh...

• 1:27Neil deGrasse Tyson?

  Yeah, sorry. I meant to warn you in advance.

• 1:30Matt Kirshen?

  Aren't chemicals dangerous? Yeah, do we need to, uh... Does it need to be a warning? Does it need to be the yellow tape around me? What's going on? What are we gonna... Hopefully, we'll find out.

• 1:40Neil deGrasse Tyson?

  Now, so I know a little bit of chemistry because we need it in astrophysics, but not enough to be the source for this show. We combed the landscape and we rediscovered Kate Biberdorf. Kate, welcome back to StarTalk.

• 1:58Kate Biberdorf?

  Thank you so much for having me. I'm so excited to be back.

• 2:01Neil deGrasse Tyson?

  Yeah, Kate, Kate, your moniker, your online moniker is Kate the Chemist.

• 2:05Kate Biberdorf?

  Yes.

• 2:06Neil deGrasse Tyson?

  And I love it. Wow, you have a PhD in chemistry and you're now Associate Professor of Instruction and of Chemistry at the University of Texas at Austin. So, that's just the kind of expertise we need when we comb our Patreon members who get exclusive access to the questions on our Cosmic Queries. So, Matt, you've collected them? I haven't seen them.

• 2:34Matt Kirshen?

  I have.

• 2:35Neil deGrasse Tyson?

  I don't think Kate has seen these questions either.

• 2:36Matt Kirshen?

  There are a lot.

• 2:37Neil deGrasse Tyson?

  Only Matt has seen these questions.

• 2:38Matt Kirshen?

  There are a lot of very good questions.

• 2:39Neil deGrasse Tyson?

  So, yeah, we'll see if he stumps you.

• 2:40Matt Kirshen?

  It's gonna, it's gonna, I'm gonna try and get through them all. I apologize to any Patreons we, patrons we don't get through, but, uh, because there's a lot of good ones. So, let's kick off with Soran Sarkar asks, "At what point after the Big Bang can we say chemistry came into existence from the physics of the early universe?"

• 2:56Neil deGrasse Tyson?

  Whoa, whoa.

• 2:58Matt Kirshen?

  Yeah, sorry to drop that one right on you at the beginning.

• 3:01Neil deGrasse Tyson?

  Damn.

• 3:02Matt Kirshen?

  Tell us when your entire field of study started.

• 3:04Kate Biberdorf?

  Could we, could we start with like the structure of an atom?

• 3:06Neil deGrasse Tyson?

  Well, let me, let me tee up Kate here. So Kate, like early universe is really, really, really, really hot and as we expand, it slowly cools. So, as I remember, high temperatures are not good for making molecules. So, what are some molecules that you might make first in the highest of temperatures as the universe cools?

• 3:30Kate Biberdorf?

  Well, in the very beginning, we really only had two elements. I mean, we think that we only had the two of hydrogen and helium and that was the very beginning and the two of those reacted together. They kind of existed together for quite a period of time. And after some time when the universe started cooling down, that's when we were able to actually start the molecules, just like you were saying. Because chemistry and the formation of molecules is all about exchanging electrons. And so nuclear chemistry, which is what happens a lot in In space, that's about the core, the nucleus. But chemistry here on Earth is all about electrons. And so in order to form a bond between two atoms, we need to have some kind of electron exchange. So they're either gonna transfer atoms, or they're gonna electrons, or they're going to share their electrons.

• 4:15Kate Biberdorf?

  And unfortunately, when the temperatures are really, really hot, these atoms can't even hold on to their electrons. So in the very beginning, we didn't really have hydrogen and helium atoms. We had the nucleus. And so we had a species with one proton, or a species with two protons. And so, once the universe finally cools down, that's when we can start actually forming these bonds between each other, because the atoms can now hang on to their electrons. So a classic molecule that we just, there was like a big hoodoo about it a couple of years ago, was the helium-hydrogen molecule that was formed.

• 4:49Neil deGrasse Tyson?

  What?

• 4:50Kate Biberdorf?

  H E H plus.

• 4:51Neil deGrasse Tyson?

  What?

• 4:52Kate Biberdorf?

  Yeah. Yeah.

• 4:53Neil deGrasse Tyson?

  No, no, that's not allowed. No, no.

• 4:57Kate Biberdorf?

  What do you mean that's not allowed?

• 4:59Neil deGrasse Tyson?

  No, that doesn't have my permission.

• 5:01Kate Biberdorf?

  I was like, that's right.

• 5:02Neil deGrasse Tyson?

  Helium does not have my permission.

• 5:04Matt Kirshen?

  If there's one thing I know about helium, well, it's the squeaky voice thing. But if there's two things I know, that it doesn't form any, any bonds with anything. So what, what do you have to do to make helium?

• 5:13Kate Biberdorf?

  On Earth.

• 5:14Neil deGrasse Tyson?

  What magic are you, what sorcery are you committing in the early universe to make this happen?

• 5:19Kate Biberdorf?

  Well, we have to have high temperatures. That's a big piece. And so we have to have enough. And there's also a velocity component. Those are the two main pieces. So these two protons, or these two species, have to slam into each other with enough velocity and high enough temperatures in order to basically have that strong force engaged.

• 5:36Neil deGrasse Tyson?

  All fusion, oh, okay, got it. All in, all in. I, I thought they were somehow, the helium atom, like, full up with its electrons, was somehow mating with a hydrogen atom to make a H E H molecule. Okay.

• 5:52Kate Biberdorf?

  No.

• 5:53Neil deGrasse Tyson?

  Oh, man.

• 5:53Kate Biberdorf?

  Yeah.

• 5:54Neil deGrasse Tyson?

  I was sweating there for a minute. Okay.

• 5:56Kate Biberdorf?

  No, but it's just, usually in space, we don't find very many molecules, because it's very difficult. The, the, the temperatures are unique, the, the conditions are really unique. And so oftentimes, we find... Species without their electrons on them. So we're not finding full atoms. We're finding these charged ions. And so in order to have the molecule, you really need to have that atom component so that we can have that electron exchange. It's fascinating stuff. It's wacky stuff because here on Earth, that just doesn't happen easily.

• 6:22Neil deGrasse Tyson?

  We don't get the nuclear stuff. Yeah, the nuclear thing.

• 6:24Kate Biberdorf?

  Exactly. Yeah, we don't have nuclear chemistry. And so we have just regular old chemistry here.

• 6:28Matt Kirshen?

  There's a follow up question from Soren that I think is related to this. That is, is it possible for the periodic table of elements to be different in another part of the universe with vastly different conditions? Or do we need another universe with different fundamental laws for that to happen?

• 6:40Neil deGrasse Tyson?

  Ooh, I love that question.

• 6:42Kate Biberdorf?

  I do too. So let me give my answer. And then Neil, I want to hear your answer to that, if that's okay.

• 6:46Neil deGrasse Tyson?

  Sure.

• 6:46Kate Biberdorf?

  Because my answer would be no. In this universe, we all have the same building blocks. We all started with the hydrogen and the helium components. And so we are going to then form the exact same elements with these same building blocks when we change the number of neutrons or protons or electrons that a sample has. So here in our universe, I personally think our periodic table is locked in with these elements. We can discover new ones still, but I don't think we're going to have completely different conditions.

• 7:18Neil deGrasse Tyson?

  Yeah, I agree entirely.

• 7:20Kate Biberdorf?

  Do you agree?

• 7:20Neil deGrasse Tyson?

  Yeah, we get, we look at spectra of stars, galaxies across the universe. And the spectrum matches what we can produce in the laboratory for the various chemical elements. So you look at like what carbon looks like, sort of when you burn it in a lab, and it has a signature in the spectrum. And you find that same signature as you look out into the universe. So these, all these same elements are there. So we have no reason to think that the periodic chart would look different at all. And Kate, plus the chart is full, right? I mean, there's no room.

• 7:56Kate Biberdorf?

  Well, well, I'd fight you on that.

• 8:00Kate Biberdorf?

  They're Professor Ogden Eason. Yeah, let's go. So Professor Ogden Eason over in California would absolutely fight you on this. And so he has been responsible for the last like six or seven elements that have been discovered. He has this fascinating technology.

• 8:13Neil deGrasse Tyson?

  Oh, they have. Oh, wait. I get you. Okay. So we're adding at the extreme end, but we're not crowbaring other elements in.

• 8:19Kate Biberdorf?

  No.

• 8:20Neil deGrasse Tyson?

  That's all I meant. That's all I meant. That's all.

• 8:22Kate Biberdorf?

  Yeah, I agree with you that the first like 118 are locked in. But after that, we're still forming new ones. I mean, we could even go to another row on the periodic table. I don't know that I will ever see that personally. I'm optimistic that we will, but I don't know. Maybe like my like great, great, great, great grandchildren would see something like that.

• 8:39Neil deGrasse Tyson?

  Hmm.

• 8:40Matt Kirshen?

  I think this segues quite neatly into the question from Scott Bringlow, AKA Scott the Pilot, who has two granddaughters who are curious and science, science curious granddaughters, young kids. Firstly, says, can you say hi to Beatrice and Louisa?

• 8:53Kate Biberdorf?

  Hi Beatrice. Hi Louisa.

• 8:54Neil deGrasse Tyson?

  Okay.

• 8:56Matt Kirshen?

  And yeah, Scott's very grateful to have a growing community of female role models in science. And also asks, Scott was wondering about combining atoms under normal earthly conditions and then about where in the universe atoms combined because of extreme conditions of temperature oppression, perhaps. Where do we find strange compounds that would not exist on Earth? So you've already, you've already discussed this a bit with hydrogen and helium combining.

• 9:18Kate Biberdorf?

  Mm hmm.

• 9:18Neil deGrasse Tyson?

  Well, that, okay, but that would be a nuclear fusion, but I got a good one for you. Okay. Um, so Kate, we learned in, in chemistry class that hydrogen is sometimes a metal. Right? Like it's on both sides of the periodic table, which was kind of freaky to me. And I didn't fully understand that until I took astrophysics. So do they teach how it is that hydrogen can become a metal in the class? Do you teach it in your classes?

• 9:48Kate Biberdorf?

  Not in general chemistry. No, that's a little advanced.

• 9:50Neil deGrasse Tyson?

  Right. That's what I'm saying. It wasn't really there.

• 9:52Kate Biberdorf?

  Yeah, not, not in your basic classes. You really learn more about that when you go into the lab. So I, my first introduction to it was when I used lithium aluminum hydride. And my graduate student was like, okay, this could kill you. So let's have a conversation about it. And it's like, oh. Okay.

• 10:08Kate Biberdorf?

  Um, but yeah, just to answer your question.

• 10:09Neil deGrasse Tyson?

  Half the stuff on that table can kill you.

• 10:10Kate Biberdorf?

  Yeah, exactly. Half the stuff on the table could kill you. But usually it has to do with the charge on the atom. So when hydrogen is negatively charged, it can behave more like a metal. Whereas when hydrogen is positively charged, it operates more like the gas itself. And we have the cool properties that you probably are familiar with because it's similar to what would happen out in the universe and space.

• 10:30Neil deGrasse Tyson?

  Right. So in the core of Jupiter, under very, very high pressure, Jupiter has, is mostly hydrogen and helium. It's gaseous. It's damn near like a star in its composition. And the helium, but the hydrogen in the core, under very extreme pressures, creates the metallic properties of the hydrogen. And those metallic properties then create, enable dynamos to form, which creates a very strong magnetic field. So Earth has a magnetic field because we have an iron core and that itself is magnetic. But Jupiter has a magnetic core because of what it's done to hydrogen. And, and that's when I first saw hydrogen, or knew of a place where hydrogen behaved this way under natural causes.

• 11:15Matt Kirshen?

  That, so that kind of relates, Joey Santos asked, I'm just going to combine this. For, uh, are there any theorized molecules that are only made possible to exist outside of the bonds of this planet due to cosmic phenomena or some sort that we can't, that we can't recreate? And I'm wondering actually, because that second part of the question, it sounds like it might not happen naturally, but some of these things can be recreated under extreme lab conditions and.

• 11:38Neil deGrasse Tyson?

  Yeah, once you know how you can create it. I got one in the universe, but Kate, do you, do you have any, uh, were there any that eluded us until our lab experiments got better?

• 11:46Kate Biberdorf?

  Oh, yeah.

• 11:47Neil deGrasse Tyson?

  That you.

• 11:47Kate Biberdorf?

  Oh, absolutely. So like xenon, we thought xenon was an inert gas forever. It, it is in the periodic table. It's a couple below helium. So we would expect for it to be inert. But once we got into the lab, we were actually able to make, um, XE F4. Um, so put four fluorines on it and that was, that was shocking. People were not expecting that at all because you thought it was an inert gas. But it turns out it's only inert under certain conditions. What's the one in the universe you have?

• 12:12Neil deGrasse Tyson?

  Um.

• 12:14Neil deGrasse Tyson?

  Wait, wait. So, so that, okay, that reminds me, Kate. So the properties that we list for your 118 elements have to, we all have to agree under what condition those properties are being reported.

• 12:29Kate Biberdorf?

  Yes.

• 12:29Neil deGrasse Tyson?

  Right? So, so if we say it's liquid, well, it's only liquid in a certain temperature range.

• 12:36Kate Biberdorf?

  Exactly.

• 12:37Neil deGrasse Tyson?

  So it's not natively liquid. It's just happens to be liquid because we're measuring it in our own labs at 72 degrees.

• 12:45Kate Biberdorf?

  Fahrenheit to 25 Celsius. 25 Celsius. I gotta throw that in there.

• 12:50Neil deGrasse Tyson?

  No, excuse me. Okay.

• 12:52Kate Biberdorf?

  Go ahead.

• 12:53Neil deGrasse Tyson?

  25 Celsius. Excuse me.

• 12:55Kate Biberdorf?

  Well, you use Fahrenheit. That's like the only F word I don't allow in my classroom. Like, I'll take everything else.

• 13:03Neil deGrasse Tyson?

  So someone could say, "F Celsius," and that's just fine.

• 13:06Kate Biberdorf?

  I find that. I don't care.

• 13:10Matt Kirshen?

  Because they're more of a Kelvin fan? What are we doing here?

• 13:13Kate Biberdorf?

  Well, we just, in chemistry, you don't use Fahrenheit. You just don't do it. So it's either gonna be Celsius or Kelvin. And so, yeah.

• 13:18Matt Kirshen?

  Can I ask, um, because this is me remembering.

• 13:21Neil deGrasse Tyson?

  Wait, I'm not done with it. Wait, wait, wait. Hold on. Hold on. Okay, so I guess what I'm saying is on the chart, where you have room temperature at 25 degrees Celsius, that to say something is a liquid reported as a property of the element, it kind of doesn't make sense to report properties of elements unless you have a full discussion under what conditions you are measuring those properties.

• 13:48Kate Biberdorf?

  Yeah, that's an excellent point. And so we always talk about STP, so standard temperature and pressure. And so in general, if we don't say otherwise, it is safe to assume we are under the conditions of 25 degrees Celsius, which is like loosely room temperature, and then a pressure of one atmosphere, which is again loosely the pressure on Earth. And so in my class, I say this all the time. Like, we are only studying the things on Earth. So that's why we use these conditions. And then when we move to astrochemistry, that's when we take ourselves off of Earth and move into the universe, where it's more nuclear chemistry, whereas on Earth, it's more chemistry, chemistry, like traditional chemistry.

• 14:27Neil deGrasse Tyson?

  All right. And so, and one more thing, Matt, and then I'll, then I'll hand it back. You can have the, the speaker's mallet or whatever. What do they pass around?

• 14:35Kate Biberdorf?

  Microphone?

• 14:39Neil deGrasse Tyson?

  Okay, the early version of the microphone was, I think, was a speaker stone or something. You couldn't speak unless you had the stick.

• 14:45Kate Biberdorf?

  Oh, yeah.

• 14:45Neil deGrasse Tyson?

  Speaker stick. So, a friend of mine from the UK noted for me that there's an element that is solid in the UK, but liquid in the United States.

• 14:58Kate Biberdorf?

  Gallium?

• 15:01Neil deGrasse Tyson?

  Maybe it was gallium, because in, in the UK, their room temperature was colder than in the United States.

• 15:08Kate Biberdorf?

  I bet it was gallium.

• 15:09Neil deGrasse Tyson?

  By a few degrees. So what's the melting point of gallium?

• 15:12Kate Biberdorf?

  Uh, probably, let me look that up, actually. I'm really curious about that. It's, it's really close.

• 15:17Neil deGrasse Tyson?

  You had to memorize the whole table, I'm so disappointed.

• 15:18Kate Biberdorf?

  It's thirty degrees Celsius. So just a little bit warmer than room temperature. So, which is eighty-five degrees Fahrenheit for the Americans.

• 15:26Matt Kirshen?

  So, hang on, remembering from school chemistry, I like, I thought all the noble gases were inert because they've got full electron shells. So how do you get four fluorine atoms onto, onto one?

• 15:39Kate Biberdorf?

  First of all, fantastic job on that. That is amazing that you remember that they have full electron shells and that's why they're not reactive. So they're not hunting for another electron. I'm very impressed by that.

• 15:49Matt Kirshen?

  A-level chemistry from twenty years ago, still hanging on in there.

• 15:53Kate Biberdorf?

  Great job. Your high school teacher would be so proud, or whoever teaches A-levels at that. Um, but the, the, the answer is extreme conditions. Like, that's always the answer when it, when you make something work that you're not expecting to. It's extreme conditions. And usually for us, we can alter pressure, volume, and temperature. And so if we do something at a low volume, then it's going to force these atoms to interact. And so for chemistry, it's all about collisions. Did they collide and did they have the proper orientation? So for example, if I have one thing that's horizontal and another thing that's vertical and they slam into each other, it might not be a favorable interaction. But if they now move around the flask a little bit more and now they're both horizontal and they slam into each other, now they can actually form that molecule.

• 16:37Kate Biberdorf?

  So it has to do with how they collide and in what orientation. And so-

• 16:41Neil deGrasse Tyson?

  Man, that's more complicated than I ever-

• 16:43Kate Biberdorf?

  It's very complicated, yeah. Because you don't necessarily have a reaction just because the molecules collide. You have to have the proper conditions. And high pressure really helps that because it's forcing those collisions to occur. It's forcing those atoms or molecules, depending on what you're studying, to actually go through those collisions, breaking bonds, forming new bonds. And you just need to have those collisions in the right orientation.

• 17:04Neil deGrasse Tyson?

  All right, we gotta take a quick break, but when we come back, more with Kate the Chemist in Cosmic Queries, the chemicals edition. We'll be right back.

• 17:23Speaker 03

  I'm Joel Cherico, and I make pottery. You can see my pottery on my website, cosmicmugs.com. Cosmic Mugs, art that lets you taste the universe every day. And I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 17:46Neil deGrasse Tyson?

  We're back. StarTalk, Cosmic Queries, the chemicals edition with Kate the Chemist. All right, we got Matt Kirshen with us, reading us the questions.

• 17:55Matt Kirshen?

  Yeah.

• 17:55Neil deGrasse Tyson?

  So Matt, give it to me.

• 17:57Matt Kirshen?

  Don Lane from Michigan says, "I recently read an article about how the asteroid, is it pronounced Ryugu, R-Y-U-G-U, was full of organic molecules. What does that mean for possible life in the galaxy?"

• 18:09Neil deGrasse Tyson?

  Yeah, I mean, you know, when we looked out in the universe, wondering whether life was rare, and then we find the building blocks of life everywhere. So Kate, how important do you think, if, so let me say that differently, if these asteroids and comets hit Earth, delivering these basic ingredients, what more do you need to give us life?

• 18:34Kate Biberdorf?

  I mean, that's, that's a basic part of it, right, is you need the main things that our bodies are comprised of. So you need the carbons, you need your hydrogen. In our personal human body, we also need oxygen. That's the number one thing we need. And so, we were able to sustain life here on Earth because of its atmosphere. I mean, it is 21% oxygen, even though it's primarily nitrogen, that oxygen on Earth is what we need to sustain life. So, if we were to have life over on other planets, somewhere else in the universe, depending on what that, I'm just gonna say human, but whatever their body is, whatever their species is, they are going to have something else that they need in order to breathe and function. And so, maybe it's not oxygen, maybe it's nitrogen, because their system operates a little bit differently.

• 19:18Neil deGrasse Tyson?

  Okay, so, but you're saying it's, it's necessary to have these ingredients...

• 19:24Neil deGrasse Tyson?

  But maybe it's not sufficient. We need some other things going on. In other words, if if you just have a tide pool with all the right ingredients, will some creature crawl out given enough time? Or do we not know enough about that transition to to to say at this point?

• 19:41Kate Biberdorf?

  I do not think we know enough about that transition, but I do think that when we have atoms around each other under the right conditions, like like the extreme conditions, a lot of things can happen. I mean, we're very far away from doing crazy nuclear chemistry here on Earth, but we can see out in the universe that when you're at high temperature and when you have high velocity, really fascinating molecules can form. So it really just depends on the conditions and, you know, how close that particular planet is to their sun. Are they really close? Is it very hot? Because you're going to have different reactivity than if we're at something like Pluto, which is really, really, really far away from the sun, completely different chemistry.

• 20:20Matt Kirshen?

  Well, that that also kind of connects to a listener Kenneth from Atlanta, who says, we talk about the Goldilocks zone, the importance of liquid water and other chemicals in the periodic table that could be analogs to the biochemistry on Earth. But are there any models that investigate biochemistry based on completely different temperature scales and different phases of matter? So I think that relates to what you were talking about with these different conditions on these different parts of the.

• 20:41Neil deGrasse Tyson?

  Yeah, yeah, Kate, what is STP on another planet? Can can you do you guys think about pot life under those very different conditions? Maybe not liquid water, but.

• 20:52Matt Kirshen?

  Yeah, Kenneth says exactly that. It says, what might be different chemicals in liquid form that could serve as a metabolite on different and what gases could be breathed in different areas?

• 21:00Neil deGrasse Tyson?

  Right. My favorite, I saw a comic from The New Yorker where there's there's aliens that just crash landed in the desert and they're pulling themselves along the the desert floor and they're saying ammonia, ammonia.

• 21:16Neil deGrasse Tyson?

  So can you imagine that?

• 21:18Kate Biberdorf?

  Yes, I can. I can see a system based off of nitrogen. So our system here on Earth is typically pretty heavy in carbon, hydrogen, and oxygen. Like, those are our big pieces. And so something that is just a neighbor of that is nitrogen. And so it would not be that unusual for me to see or to, to, I guess, to believe that we could have other life forms that are dependent on nitrogen. So maybe they breathe nitrogen gas. Uh, maybe they need to drink ammonia because that's what works in their system. But for us, because our-

• 21:49Neil deGrasse Tyson?

  Ammonia is a chemical symbol for ammonia?

• 21:51Kate Biberdorf?

  NH3.

• 21:52Neil deGrasse Tyson?

  NH3, so that's your nitrogen showing up there again.

• 21:54Kate Biberdorf?

  Exactly, yeah. And but I think a huge part of it, just to go back to what you said about STP, is here on Earth is we do have an atmosphere. And so we do have all these gases that are pushing down on us, and we have chemical reactions based on that. But in other planets, they don't have the atmosphere, so they don't even have that pressure. So what people would, people, but what that life form would be breathing in or not? That's what's weird for me. I have a hard time with that piece. Because like, how would that work if there's no atmosphere? So for me, I personally believe that if there is life in other places, there's got to be an atmosphere in order for those natural chemical reactions to occur. What do you think?

• 22:32Neil deGrasse Tyson?

  All right. Yeah, I think, or it can happen underground, right?

• 22:36Kate Biberdorf?

  Oh, yeah.

• 22:37Neil deGrasse Tyson?

  I mean, you can have pressures underground where you don't have to worry about what's above ground. In fact, I, did I just recently learn this, Kate? You're closer to this than I am in the biology world, that there may be a greater biomass beneath Earth's surface than above it.

• 22:54Kate Biberdorf?

  I heard that too, yeah.

• 22:55Neil deGrasse Tyson?

  If you added it up, do you, do you, this is something you remember from biology literature?

• 23:00Kate Biberdorf?

  I remember hearing about that, yes, and so-

• 23:02Neil deGrasse Tyson?

  Yeah, I only just, I, I just heard about it, right? But if that's true, that's, that's just amazing, right? It meant, here we are thinking how important the surface is and sunlight and this and that and that. And it's like, no, most organisms don't give a rat's ass about the surface.

• 23:16Kate Biberdorf?

  Exactly.

• 23:16Neil deGrasse Tyson?

  And but what that also means is judging whether Mars has life should not be a conversation about how hostile the surface is to life.

• 23:26Kate Biberdorf?

  Perfect, yeah.

• 23:27Neil deGrasse Tyson?

  And tell me, I'm gonna slip this in. Matt, do I have permission to put in a question? Uh, granted.

• 23:33Neil deGrasse Tyson?

  Okay, thank you.

• 23:36Neil deGrasse Tyson?

  We learn that ultraviolet light, which is not shielded on Mars from the sun, is hostile to biology. What is going on there? What is the ultraviolet? Why is it hostile to anything at all if it's just light?

• 23:55Kate Biberdorf?

  Well, it's hostile here on Earth. I mean, the ultraviolet light is what causes skin cancer. And so it's such high-energy radiation that it actually can kick off electrons off of atoms. And so in our electromagnetic spectrum, our weakest energy is going to be radio and microwaves. Then you have infrared, and then your visible region. And then directly on top of that, that's where your ultraviolet kicks in. And so your ultraviolet, your X-ray, your gamma rays, those three main categories are such high-energy radiation that they can spit that electron off of the atom. And when that happens in our body, that's what causes skin cancer. And so we really need to wear a sunscreen because essentially we have sacrificial molecules that we put on top of our skin that die.

• 24:39Kate Biberdorf?

  They split, okay? They split, their bonds split. And that's what protects us because those molecules die. And then the ultraviolet radiation essentially goes to those molecules. So you need to reapply.

• 24:50Neil deGrasse Tyson?

  So you're saying the sunscreen is your sacrificial shield?

• 24:52Kate Biberdorf?

  Yep, 100%.

• 24:53Neil deGrasse Tyson?

  Okay.

• 24:54Matt Kirshen?

  Oh, interesting.

• 24:55Neil deGrasse Tyson?

  I hadn't thought about it that way. Yeah.

• 24:57Matt Kirshen?

  I didn't realize. I thought it sort of just bounces it in some way. I didn't realize it kind of works almost like a bike helmet where it just breaks instead of your head.

• 25:04Kate Biberdorf?

  It's sunscreen versus sunblock. And so sunscreen has molecules in there that essentially absorb the ultraviolet radiation. And when that happens, their bonds break. And now they're no longer active. They can no longer protect you. And so you only have X amount of molecules you put on your body. And so when you run out of those sacrificial molecules, now you're just exposed. You're just sitting there with the UV radiation hitting your skin.

• 25:26Neil deGrasse Tyson?

  Damn.

• 25:27Kate Biberdorf?

  Yeah.

• 25:27Neil deGrasse Tyson?

  Wait, wait. So, so my clothing would be a sunblock?

• 25:30Kate Biberdorf?

  Correct. Yeah. Physically, yeah, it's a physical blocker. And so the, the sunblock is like a physical blocker. And so for those, you're using nanoparticles, um, and yeah, like zinc or titanium.

• 25:43Matt Kirshen?

  Interesting.

• 25:44Neil deGrasse Tyson?

  But wait a minute, Kate. Uh, yes, we get that UV causes skin cancer, but there are UV chambers in hospitals that sterilize, uh, surgical equipment. And we're not asking whether those microbes are getting skin cancer. So what, what else is, what else is the UV doing to the, these?

• 26:05Kate Biberdorf?

  It's the same thing. It's splitting the molecules. And so if you have essentially bad molecules on, you know, your, your scalpel or whatever it is they're going to use in the hospital, you're killing the bacteria and you can actually use UV radiation to do that. Um, when COVID-19 kind of came out, they weren't sure in the very beginning if UV was going to be strong enough. They did a lot of research and they found out that we could actually use UV radiation to kill the COVID-19 piece. And so that's kind of neat.

• 26:31Neil deGrasse Tyson?

  So there's the, the virus, um, getting skin cancer.

• 26:37Kate Biberdorf?

  That's a good way to think about it, though. I've never thought about it like that.

• 26:40Neil deGrasse Tyson?

  Whichever the, the basic molecular structure of the virus is, the UV is bust, busting it open.

• 26:46Kate Biberdorf?

  The important part, not every bond. I don't want to imply every bond, but the important parts that make it dangerous, it breaks those bonds to basically make that virus no longer active. And so that's what sterilizes.

• 26:58Neil deGrasse Tyson?

  Very good. Very good. Okay. Thank you. I slipped my question in that I'm not even a Patreon.

• 27:02Matt Kirshen?

  I know, I know. Shameful.

• 27:04Neil deGrasse Tyson?

  Yeah, that's.

• 27:04Matt Kirshen?

  The, the real patrons are going to be furious that an interloader is sneaking in.

• 27:10Neil deGrasse Tyson?

  Yeah.

• 27:11Matt Kirshen?

  Terese Talbot from Columbia, South Carolina says, are there any places in space where we cannot go due to reactions between a rocket's exhaust and potentially volatile chemicals in surrounding space?

• 27:22Kate Biberdorf?

  I would say tentatively no, because usually space is the absence of molecules. And so I feel okay saying that there are protons moving around. I feel okay saying that there are some atoms in some areas. But in terms of having really big molecules that are going to have reactions, that's kind of limited. Now, all that being said, when we have, and Neil, you're gonna have to fine tune this, but when we have supernovas that explode, or they do their thing, then we can throw out those polyaromatic hydrocarbons. And those are out there, and we know that those can have reactivity. But in general, those are mostly stable.

• 27:59Matt Kirshen?

  So there's no need to strap a canary to the front of the rocket?

• 28:02Neil deGrasse Tyson?

  No.

• 28:03Kate Biberdorf?

  I love that.

• 28:04Neil deGrasse Tyson?

  It would die for other reasons, I think. It wouldn't. It has to die for the reason you had in mind. Not a... So I'm just thinking, in the app, in the empty space, of course, Kate, that's right. There's no, there's nothing for your exhaust to interact with. So it'll just stay there as exhaust. But it had to take off from Earth's surface at some point, or at some other planet's surface that might have had an atmosphere. So we can ask, does it interact with Earth's atmosphere when it launches? And I can tell you that the main rockets, not the solid rocket boosters, but the main large engines are just hydrogen and oxygen in liquid state.

• 28:46Neil deGrasse Tyson?

  And they're brought together with these valves. And Kate, tell us what happens when we combine hydrogen and oxygen.

• 28:54Kate Biberdorf?

  We have a very beautiful combustion reaction. And so this is clean energy. And so hydrogen is an excellent source of fuel. It releases something like 286 kilojoules per mole of hydrogen. It's a beautiful source of fuel. And it doesn't have any carbon. Okay, so hydrogen by itself doesn't have carbon. So it doesn't release carbon dioxide. And that's why it's very clean and green, and we're not contributing to climate change.

• 29:19Neil deGrasse Tyson?

  Yeah, so the rockets that you see with all their plumes, the exhaust, most of that exhaust is just water vapor, I guess, right? I mean-

• 29:27Kate Biberdorf?

  That's my understanding of it, yeah. It's primarily water vapor.

• 29:29Neil deGrasse Tyson?

  Yeah, I don't want to go and breathe it, like, while that's happening, because I think I would get cooked.

• 29:33Kate Biberdorf?

  Right.

• 29:33Neil deGrasse Tyson?

  But, right, there's no other chemicals. No, there are different chemicals in the solid rocket boosters, but our mainstay throttleable engines are hydrogen and oxygen. And Kate, isn't that what they're talking about as another energy source for cars?

• 29:48Kate Biberdorf?

  Oh, yeah. Absolutely.

• 29:50Neil deGrasse Tyson?

  How real is that? I mean, speaking as a chemist.

• 29:53Kate Biberdorf?

  I, so I am optimistic. I would love for that to happen. What I get nervous about is, in general, how would we do that? And so, do you strap a hydrogen tank to the back of your car? So, like, the logistics of it makes me extraordinarily nervous, because-

• 30:07Neil deGrasse Tyson?

  And these are called fuel cells, I guess, right? That's a fuel cell.

• 30:09Kate Biberdorf?

  Well, yeah, yeah. You would, you would likely use a fuel cell in this, and so you would need some kind of way to constantly input hydrogen. So, a fuel cell is a cell or a battery, depending on how you want to talk about it, where you're constantly introducing your source of fuel, and so you would need a source of hydrogen. What I would love to see is if we would find a way to kind of do that safely, so that we could burn hydrogen on our cars without producing carbon dioxide. To me, though, from my understanding of it, that just seems like a logistical nightmare.

• 30:38Neil deGrasse Tyson?

  So, let me remind people that the Hindenburg was kept afloat by hydrogen. Okay? So, if you have a tank of hydrogen, well, maybe it's not worse than a tank of gasoline. I mean, I don't know, I'd have to-

• 30:50Matt Kirshen?

  No spoilers, but how did it go?

• 30:52Neil deGrasse Tyson?

  Oh, with, for the Hindenburg?

• 30:53Matt Kirshen?

  Yeah.

• 30:53Neil deGrasse Tyson?

  Yeah, no, it, yeah, it, no, it was, it's, yeah, that didn't end well for the, for the Hindenburg. So, Matt, let's see if we can slip one more question in.

• 31:04Matt Kirshen?

  Okay, I'm gonna, I'm gonna be cheeky and, and combine two questions, because they're both about iron. Thomas Cochrane, who's also a hematologist, so, really, really into iron, and very happy to see Kate, the chemist, returning, says, "I think iron is pretty neat. I also learned iron is responsible for the deaths of the largest stars in the universe. What is the unique chemical characterization of iron that makes it consume energy when it undergoes fusion or fission?" And then Fadi Hayek says, "We learned from Neil that the fusion process when stars form ends with a thud in iron, so how come there are heavier elements on Earth? Where did they come from?"

• 31:35Neil deGrasse Tyson?

  Ooh.

• 31:35Matt Kirshen?

  I think those are two quite, those are two questions that I think are playing in the same, in the same pool.

• 31:39Neil deGrasse Tyson?

  Getting all up in it. Well, okay, we don't have time to answer that in this segment. We can put a pin in that. And when we come back, more Cosmic Queries, the Chemicals Edition with Kate the Chemist. Be right back.

• 32:03Neil deGrasse Tyson?

  We're back. Startalk Cosmic Queries, Chemicals Edition with Kate the Chemist. And it's Kate Bieberdorf, who is an Associate Professor of Chemistry and Science Instruction at UT Austin. And Kate, you now host a podcast.

• 32:19Kate Biberdorf?

  I do.

• 32:20Neil deGrasse Tyson?

  That is about to drop, that's sponsored by NPR, National Public Radio. So what's that about?

• 32:25Kate Biberdorf?

  I'm so excited to announce this. It's called Seeking a Scientist, and it's basically my dream job. I get to interview scientists doing cool, cool science and highlight their amazing research. And we're really focusing on unique things that you might not know that much about. And so, of course, we're going to tackle the fungus zombies. We've got to talk about that. There's some new research out where you can reverse aging. So you can actually reset a heart by 10 years. So we're talking to scientists doing that. So it's just absolutely fascinating research. And my goal is to just turn scientists into rock stars.

• 33:00Neil deGrasse Tyson?

  Excellent, excellent. Especially if the science they're doing directly affects people's lives. Oh, my gosh. All of a sudden, people will start caring about them in ways they never thought, that any of us thought was possible. So congratulations on that.

• 33:14Kate Biberdorf?

  Thank you.

• 33:14Neil deGrasse Tyson?

  We look forward, maybe you can come back and tell us, yeah, we'll totally get you back to talk about some of who you interview.

• 33:21Kate Biberdorf?

  I'm gonna hold you to that. Let's do it.

• 33:23Neil deGrasse Tyson?

  Okay, totally. And Matt, you're, you're still hosting Probably Science, correct?

• 33:28Matt Kirshen?

  Yeah, so that's, that's still going on. So yeah, I love it when we found a bunch of listeners, thanks to you and your show. So, hi, fellow mutual listeners. And then I'm on the road.

• 33:38Neil deGrasse Tyson?

  And I was a guest on, was it 30 years ago I was a guest on your show?

• 33:43Matt Kirshen?

  Open invitation, anytime. But I want to save you 20.

• 33:48Matt Kirshen?

  Yeah, the second you.

• 33:49Neil deGrasse Tyson?

  You don't call, you don't write, you know.

• 33:51Matt Kirshen?

  The second you need a 0.01% bump in your book sales, we are here.

• 33:57Neil deGrasse Tyson?

  Okay.

• 34:00Neil deGrasse Tyson?

  So what goes on on your on your on your show?

• 34:02Matt Kirshen?

  Well, normally we go through the weekend science news with other comedians. So we get comics on, we talk about what's been happening, we riff with them. And then every so often, we do a special episodes where we have real scientists on or science writers and communicators and then and we talk about them and their work. So Neil was a very special episode.

• 34:21Neil deGrasse Tyson?

  All right. Well, thank you. So we're getting back into that question you left off with. It was from a hematologist. How often do you get a conversation with a hematologist? Uh, I guess that's blood, right?

• 34:32Matt Kirshen?

  And iron specifically.

• 34:35Neil deGrasse Tyson?

  And iron, yeah, exactly. Iron specifically. And he was trying to get all up in the astrophysical situation for iron. And Kate, the, we know in astrophysics that the buck stops at iron. When you're fusing elements, it's exothermic until iron. And afterwards, it's endothermic. And then when you're fissioning elements, it's exothermic down to iron. And you try to fizz iron, then it's endothermic. So what's going on with iron that could chemically in the nucleus?

• 35:12Matt Kirshen?

  And follow up from Fadi, how how does, how do we get things that aren't iron as well in on Earth?

• 35:19Kate Biberdorf?

  Okay, so my understanding of the iron component is, like you said, it's an energy piece. It's not necessarily specifically iron or the fact that it has, you know, X, Y, or Z, but it has to do with the nuclear binding energy. And so binding energy, depending on what type of scientist you talk to, you're going to get a different definition. But when in my world, what it means is how tightly those protons and neutrons and electrons are held into that atom. So how easily can you split that atom apart into its components? And so iron has a really high binding energy. And so those protons, electrons, neutrons are really held into that atom. Nickel is right next door to it.

• 36:02Kate Biberdorf?

  And so my understanding of this is that you can actually generate some nickel, but then it radioactively decays back to iron. And so in general, when we get to iron, it's like we've run out of fuel. And so hydrogen you can use, helium you can use, carbon you can use, oxygen, silicon, all of these you can use and you can generate more fuel for the sun. I'll just call the sun. You can generate more fuel and so it can keep doing its thing. But once you hit iron, now you cannot change the atom's structure as easily. You cannot force iron to turn into another atom as easily because it takes too much energy. And so essentially it starts to implode and then you kind of just crash out.

• 36:41Neil deGrasse Tyson?

  So in a supernova explosion, there's so much energy available that it doesn't matter that you're endothermic. You can absorb energy and there's still plenty of energy around. So we can visit the heavier elements in the periodic table, but only when you have so much excess energy that it didn't matter that you ate some of it. And so, yeah, that's how you get right on up to uranium. Yeah, we're good there. Yeah.

• 37:08Kate Biberdorf?

  Pretty cool.

• 37:08Neil deGrasse Tyson?

  So Matt, what do you have next?

• 37:10Matt Kirshen?

  Okay, there are a bunch of questions from different listeners. So I'm going to combine Birin Amin, Birin Brat and Bjorn Fjörknap. I hope I pronounced that correctly. Because they've all asked questions about is there a limit to the amount of elements that can be in the periodic table? How you go about updating it? Whether you can discover new ones out there? And Bjorn wants to know whether there is a maximum possible size, whether you could even have an element that is the size, Bjorn says, of a Toyota Corolla.

• 37:39Neil deGrasse Tyson?

  I'd love that. Yeah, so Kate, where does it end? We're up to what, 118 now, you said at the beginning?

• 37:45Kate Biberdorf?

  Yeah, we have 118 elements right now on the periodic table. There's one professor who's been really driving the new formation of new elements. They're extraordinarily unstable, like they exist for less than a second. So it's unbelievably hard to characterize them and prove that you've made this element. You need high-tech equipment, you need all these things. And so it's very difficult for other places to replicate it. So right now, currently in 2023, I would say that the most Possible chance of us having new elements would be because of Oganesan in California, because he just keeps sending neutrons at different elements in different conditions to see what he can come up with, and it's absolutely fascinating research.

• 38:30Neil deGrasse Tyson?

  So I read that if you go a little heavier, maybe into the 120s, 120 number of protons, that we might have an island of stability. How real is that? Or is that just Oz off in the distance? And maybe it's not real, we just wish it were real? Where the element will last longer than a zillionth of a second?

• 38:51Kate Biberdorf?

  I don't know. I don't know. It really is going to depend on how many protons are going to be in the core, and more importantly, where the electrons are sitting in the outer shell. Um, so I don't know. I don't.

• 39:07Neil deGrasse Tyson?

  But you've heard about this, right?

• 39:08Kate Biberdorf?

  I have, yeah.

• 39:09Neil deGrasse Tyson?

  You're skeptical, you're saying?

• 39:10Kate Biberdorf?

  I am, I am. And it's just because our current research doesn't support that like at all. And so I understand why, I understand why there's the thought about that. And the position in the periodic table would absolutely affect that. So I do understand that. I just, that seems so far fetched for me, that it's just, it's one step outside of it for my personal comfort.

• 39:32Neil deGrasse Tyson?

  I wanted a fistful of element 125, whatever that would be.

• 39:35Kate Biberdorf?

  Me too, me too, someday.

• 39:40Neil deGrasse Tyson?

  All right, Matt, keep it coming.

• 39:41Matt Kirshen?

  Okay.

• 39:41Neil deGrasse Tyson?

  How many can we fit in?

• 39:42Matt Kirshen?

  Uh, Tom B. Knight, who's also a science fiction writer, wants to know, what is the most powerful chemical explosive? And is it possible we would discover something more powerful? What elements or compounds would you start with if doing this research? And that feels like both a sci-fi writer's question and also something every kid in chemistry class wants to know on the first lesson. Like, what will kill you? What makes the biggest bangs?

• 40:04Neil deGrasse Tyson?

  Cool. All right, Kate, what is it?

• 40:06Kate Biberdorf?

  Oh, hysterical. I get asked that question all the time. So that's very funny. Um, so we don't necessarily have like one, that's the most explosive, one molecule here on Earth right now. But in general, what I can tell you about these molecules is they typically have nitrogen in them. Um, not nitrogen with triple bonds bound to each other, but there are nitrogen placed across the molecule. A lot of times it's like in a nitrate form, and so those are usually what is quite explosive. And so if I had.

• 40:34Neil deGrasse Tyson?

  Interesting. So the N in TNT.

• 40:36Kate Biberdorf?

  Yes.

• 40:37Neil deGrasse Tyson?

  Comes from nitrogen, I guess, right?

• 40:38Kate Biberdorf?

  Exactly.

• 40:42Neil deGrasse Tyson?

  Wow. Okay. Because today, when we measure the strength of nuclear blasts, it's in units of TNT. So that kind of feels like we're maxing out on sticks of dynamite. But if dynamite, well, dynamite, I don't think, not technically the same as TNT.

• 40:59Kate Biberdorf?

  Right.

• 40:59Neil deGrasse Tyson?

  Are they slightly different, I heard?

• 41:01Kate Biberdorf?

  Well, it's the composition, because dynamite has other stuff in there to try to keep it stable until you want it to react, right? And so there's...

• 41:07Neil deGrasse Tyson?

  Oh.

• 41:07Kate Biberdorf?

  So you're not just like walk it around with actual trinitrotaline. That would be incredibly dangerous. So you need something to kind of stabilize it.

• 41:15Neil deGrasse Tyson?

  If you're gonna walk around with something, you want to walk around with dynamite instead of TNT.

• 41:18Kate Biberdorf?

  I mean, I guess. I wouldn't do either, but go ahead.

• 41:20Neil deGrasse Tyson?

  Oh, yeah. And Matt, that explains why the coyote always blows up.

• 41:26Kate Biberdorf?

  Yes.

• 41:27Neil deGrasse Tyson?

  Because it's TNT instead of dynamite. I remember that now.

• 41:32Matt Kirshen?

  Foolish.

• 41:33Neil deGrasse Tyson?

  He should have spoke to Kate the chemist.

• 41:35Kate Biberdorf?

  Foolish.

• 41:35Neil deGrasse Tyson?

  Oh, man.

• 41:36Matt Kirshen?

  Didn't study, didn't study enough.

• 41:38Neil deGrasse Tyson?

  Keep it coming.

• 41:38Matt Kirshen?

  All right. Well, again, I love combining questions, because James Hall from Texas says, "I'm wondering about chemistry signs of extraterrestrial life. Are we able to see enough chemistry in exoplanet atmospheres to ask if they have, to know if they have similar pollution from burning fossil fuels, for example, CFCs?" And then, this is why I asked that one first before I moved on to Richard Hart's question from Richard's nine-year-old daughter Kyrene, who says, "What kind of chemistry is happening in your body to cause you to toot? She wants to know if tooting is just you tooting at bacteria toots. I'm curious if these, quote, 'bacteria toots,' as she calls them, are what scientists are looking for in the search for life on other worlds."

• 42:17Neil deGrasse Tyson?

  Oh, my gosh. Oh, my gosh. Kate, there you go. It's in her lap now. You, I'll defer to Kate on this one.

• 42:27Kate Biberdorf?

  All right. Okay, so let's start with the extraterrestrial part. So the question was, would we predict the same pollutants in other areas? My response would be, it depends on the atmosphere of that planet. And so here on Earth, we have oxygen, and so when we burn fossil fuels, we form carbon dioxide, and that's what's causing climate change. And so if these other planets had oxygen in their environment, then yes, I would predict that CO2 would be formed if they burned something that's a hydrocarbon. I also want to fact-check what was just said. CFCs are not generated in a typical combustion reaction. Yes, they contribute to climate change. They are a greenhouse gas, but it's not necessarily a byproduct of combustion. And then

• 43:11Neil deGrasse Tyson?

  CFC chlorofluorocarbons.

• 43:13Kate Biberdorf?

  Chlorofluorocarbons, yeah, those are the ones that were banned back in the 80s when the ozone hole was getting really big. And a big piece of it is because they have a global warming potential of about 8,000. I think the number is like 8100, whereas carbon dioxide has a global warming potential of 1. And we're terrified of what carbon dioxide is doing, and that has a level 1. CFCs have 8100, so it's pretty extreme.

• 43:37Neil deGrasse Tyson?

  Okay, and then, okay, and how about tooting?

• 43:40Kate Biberdorf?

  Tooting, okay, so that has to do with what's in your body. And so essentially, what you eat is then broken down. In our stomach, we have a bunch of different versions of acid. It's essentially hydrochloric acid and some kind of derivatives of it. And so the acid goes in, your acid likes to donate a proton, and so it's going to react with what other molecules are that you just ate, and you're breaking down those species and then tooting them out. And so your toots could be composed of a number of different things based on what you've digested. So could we find life on another planet based on farts? I'm going with yes. If you somehow have a bucket of farts, then yeah, we could probably figure that out.

• 44:22Neil deGrasse Tyson?

  But, no, but the real question is, and I'm sure Matt is thinking this, he just doesn't want to ask it. Kit, are, are toots flammable?

• 44:33Kate Biberdorf?

  Absolutely.

• 44:34Neil deGrasse Tyson?

  This is the old camp question, okay?

• 44:38Matt Kirshen?

  We need to be careful about rocket exhaust in the vicinity of a gaseous person.

• 44:44Kate Biberdorf?

  Yes.

• 44:44Neil deGrasse Tyson?

  Yes.

• 44:46Kate Biberdorf?

  Yes.

• 44:47Neil deGrasse Tyson?

  I guess. So what is, what is it that's in the tooth that's flammable? What, what chemical?

• 44:51Kate Biberdorf?

  The two main primary ones would be methane. And so we know that from cows. When cows are eating their food, they're pushing out a lot of methane, so they're contributing to

• 45:00Neil deGrasse Tyson?

  I know methane because that comes out of my stove.

• 45:01Kate Biberdorf?

  Yes, yes, same thing.

• 45:03Neil deGrasse Tyson?

  That's my cooking gas, okay.

• 45:04Kate Biberdorf?

  That's CH4, and so that's extremely flammable. And then another part of it, and it's a very small portion of it, is hydrogen sulfide. And that's quite flammable as well. The sulfur typically has a rotten egg smell, and so if your, your farts ever smell egg-ish, there's likely a sulfur somewhere in your farts. I've never talked about

• 45:23Neil deGrasse Tyson?

  Wait, wait, but, but does, does methane itself have a smell? Because if it doesn't, then everything we attribute to the smell of fart would be the hydrogen sulfide, is that right?

• 45:32Kate Biberdorf?

  Yes, yes, I mean methane is definitely odorless. There's no color or anything like that. So I would say I feel comfortable telling you that methane, you're not going to smell it. But you're, you're pushing out a lot of things and so it's not just a hundred percent sulfur.

• 45:49Neil deGrasse Tyson?

  Okay.

• 45:51Neil deGrasse Tyson?

  All right, I don't, I don't know that we can follow that with another question. Okay. Let's leave that one exactly where it is. And thank Kate, oh my gosh, thank you for this. And like I said, we don't do enough chemistry on this program. And chemistry is everywhere at all times. And, and you're Kate the chemist. So I don't want to pass up any possible future opportunities to bring you back.

• 46:18Kate Biberdorf?

  I would love to.

• 46:19Neil deGrasse Tyson?

  And so when, when you're deep embedded in your new podcast, um, we'll give you another call. We'll come back and talk about how that's going. And maybe tell us about some of your favorite guests that you've had.

• 46:30Kate Biberdorf?

  Well, I've already learned you can't pick favorites. So they're all my favorites. Every scientist is my favorite.

• 46:33Neil deGrasse Tyson?

  There you go, okay. We'll pick a favorite.

• 46:36Kate Biberdorf?

  That's fair, that's fair, I'll let you do that.

• 46:38Neil deGrasse Tyson?

  All right. And Matt, always good to have you there as my co-host.

• 46:41Matt Kirshen?

  So good. And thank you to the Patreon patrons. And there were so many great questions we didn't get a chance to get to. So you're going to have to have more chemists and more, more of Kate on soon.

• 46:48Neil deGrasse Tyson?

  Yeah, definitely. We won't miss out on that opportunity. This has been StarTalk Cosmic Queries, the Chemicals Edition with our friend Kate Biberdorf. All right. I'm Neil deGrasse Tyson here, your personal astrophysicist. As always, I bid you to keep looking out.