SIO424: Semen Caught Violating Newton's 3rd Law? (the one about cum)

Transcript

This transcript was generated automatically and may contain errors — the audio is the record.

0:00:16 Thomas: Hello and welcome to Serious Inquiries Only, this is episode 424. I'm your host Thomas Smith, and I know we give you a bit of a flurry of stuff at the end of the month, just say things have been happening, as they often are, and so a few episodes at the end of month here to make up for some of the spottiness in the beginning of the month, but it all evens out to the same of things, I hope you'll enjoy them and catch up on them when you can.

So this one, been far too long since we have had Dr. Bryan Gillis, astrophysicist to the stars. That's, he doesn't call himself that, but I think he should. I feel like every astrophysis should be an astrophisicist to the stars. Unless some of them are like, I only study planets. I, I don't touch stars. I hate stars. Actually, they're the worst.

No, uh, he sent me an article a while back that he said we must do a sciencing on this one, so he's here to do a science in the clickbait article headline from newscientist.com was "Sperm Caught Breaking Newton's Third Law of Motion," see if that holds up, we'll see if that ends up being true.

0:01:15 Thomas: I have my doubts, but you know, if anything could break Newton's third law, it might be sperm, maybe. So who knows? All right, let's get on over to that. Before we do, of course, go to patreon.com/seriouspod. If you'd like to not have to hear the auto ad that's about to come. And if you want to enjoy the goodies every month, that bonus, you got a big sample of, and next month's hangout, and never having to hear auto ads, and also not having to to hear auto ads, all that good stuff, make sure to go to patreon.com/seriouspod. Thanks so much to the patrons who do, and you can enjoy going straight to this interview right now, while some non-patrons aren't so lucky. So let's get to the interview, fun guest. And Dr. Bryan Gillis, how are you doing?

0:01:56 Bryan: Oh, I'm doing well. Thank you, Thomas. How are you today?

0:01:59 Thomas: Good, although I am worried that my semen may be violating Newton's third law. Now, stay with me, listeners. It is not me saying that. That's the article that Brian sent me. I'm not just being weird, but there's something weird going on with Newton and the semen. I excited to talk about this.

0:02:16 Bryan: I'll tell you this, Thomas, there's no worry about Newton's third law applying to your semen here. Your semen is exempt.

0:02:22 Thomas: Thank God. What is the third law? Is that the equal? No, I don't know. What's the third one?

0:02:27 Bryan: Okay. Yeah. Yeah, it is. Third law is, well the way Newton originally said it is he said for every action, there is an equal and opposite reaction. Now, when he said action, we call that force these days, and action is something else. So basically, for every force, there's something else pressing back. And the way I like to describe it is, Thomas, you have cats, right?

0:02:29 Thomas: Okay. Right.

0:02:51 Thomas: Sure do.

0:02:52 Bryan: If your cat is happy, and you pat the cat, the cat will push its head up up into your hand. That's basically Newton's third law. You pat the cat, the cat pats back. And that force is always equal and opposite. When you press down, the kat presses back up against you.

0:02:58 Thomas: Right?

0:03:08 Thomas: Well, the cats actually, now maybe we need to write another news article because cats violate Newton's third law. However much you push against them, for my cats, they push about twice as hard back when they're into it. You know, they're like, Like, like they really get their head into it.

0:03:20 Bryan: Yeah. Oh, well, that actually gets into what we're seeing today because kind of the secret here. Well, but we'll get into it. Let's not spoil. So the article headline is Is sperm caught breaking the law? Newton's third law of motion, that is.

0:03:38 Thomas: I love caught. Like, I love the idea of there's just like a, there's actually a mugshot of like one sperm, you know? And he's just, oh, he's looking a little, looking worse for wear, you don't know.

0:03:40 Bryan: Yeah. Yeah. Well, imagine how hard it is to handcuff a sperm. What do you do? Wrap its tail up and then handcuff part of its tail to another part?

0:03:50 Thomas: You Yeah. Oh, you caught me. Fuck, all right. I'll do some. Community service. So what are the penalties for violating Newton's third law?

0:04:00 Bryan: Yeah. There's got to be some good sperm joke here. It's not coming to me, but effects are you basically tear apart the fabric of space-time, that space is no longer the same everywhere. It's bad, Thomas, it's bad.

0:04:13 Thomas: Okay. Oh, okay. That's real bad.

0:04:17 Bryan: Yeah, well, yeah, it's just that you have to pre-tear it apart in order to violate the third law. So some of the regular listeners might remember the episode we did on Portal, where I talked about kind of how the laws of physics are put together and how some laws are consequences of other laws. So do you remember that, Thomas?

0:04:18 Thomas: Execute that spurt! No, I'm just kidding.

0:04:41 Thomas: Yeah, I love that episode. Everyone should check it out. It's really interesting.

0:04:43 Bryan: Yeah. Yeah. So for those who didn't listen to it, The conclusion was that laws like Newton's third law of motion or conservation of momentum and conservation of energy, both of which are contributed to by the third law of motion, are caused by other underlying more fundamental aspects of the way the world works.

0:05:08 Thomas: Yeah, like symmetries, right? In space-time, kind of. What I love just to remind people from that episode, what I loved about it was, I- I'm sure most people probably know the game Portal, but just real quick, if not, you know, you shoot- you have portal gun with two doors, and then the game is really fun because you open one red door, and then you come out the blue door, wherever it is, and you can create, like, this kind of almost infinite momentum. It feels like by jumping through one in a ceiling, you know, in the floor, landing out of the ceiling, coming down. And what was so fascinating about your episode on that was when you pointed out that actually momentum momentum was not conserved, and is that because you know momentum has like a direction to it as well, right?

0:05:10 Bryan: Yeah, yeah. Yeah, momentum exactly.

0:05:46 Thomas: And that was actually really interesting to think about, because it actually matters, you know, us non-physicists, Brian. I think a lot of us remember the whole, like, oh yeah, there's velocity, and that is a direction, and you know, speed with direction. The speed is just speed, and, like, for most of us that doesn't really make a difference in our lives, that distinction in terms, you know, so yeah, whatever, velocity, speed, we're just we're moving.

0:06:04 Bryan: Well, I'll tell you, Thomas, it'll make a lot of difference to you if a bullet is going away from you versus coming towards you. Yeah.

0:06:09 Thomas: That's That's fair, but, but like that, we still would think, like, oh, okay, that's a lot of speed though. We're just like, you know, it's speed. We don't, us normies, I'm just, look, I'm representing the normies. We don't really think a whole lot about like, yeah, but is it speed with like, is it a vector though? And we're like, I don't know, man. But when you said that in the portal episode, it was actually really fascinating and telling. Like it actually made sense. You're like oh, yeah, the fact that it preserves just speed, meaning you can like switch directions kind of instantaneously and it's not actually preserving momentum, even though I think that's the thing any non-physicist would have said it was doing was like, oh, it keeps your momentum. I just found that really interesting and memorable from the episode. So maybe it'll refresh people a little bit, or if they haven't checked it out, go check it out.

0:06:20 Bryan: Yeah.

0:06:51 Bryan: Actually, and one of the notes in the, get the original game Portal, they said it conserved momentum, and I think they actually realized that and fixed it for Portal 2.

0:07:00 Thomas: They had a Brian right in.

0:07:02 Bryan: Yeah, okay, so anyways, the point there is that conservation momentum is caused by two things. One is what's called the symmetry of space, which is basically the laws of physics are the same everywhere. Like if you go over into the next room, you're not going to have different physics. They aren't even going to be slightly different, like with different constants. You're not going find gravity is weaker over there than it is here. It's all going to work the same.

0:07:31 Thomas: Except in France, it's just different, you know, it's just, they got different physics it's, you want to blend in, but you're like, I don't know how your physics works, I'm sorry.

0:07:38 Bryan: Know, you, that's really the only way they could have built the Eiffel Tower, you got to weaken gravity a bit.

0:07:42 Thomas: Then You got the leaning tower in Italy, God knows what their physics is doing over there, but okay, so things the same everywhere, got it.

0:07:47 Bryan: Yeah. Yeah. Okay. And then something that's called, the principle of stationary action, it used to be least Action, but people got a bit technical of about it. This is action in the more modern sense, which probably don't talk about it in high school physics, not really until university physics, where you talk about action, but it's basically energy in a sense, and its energy over the course of how something acts. But boiling it down, all this says is that things only move in response to forces, and all the forces are conservative. That is, they don't care what path you take to get to somewhere, they only care that you get there, which now that I say it doesn't sound conservative at

0:07:52 Thomas: My life, yeah.

0:08:31 Bryan: All. But never mind that.

0:08:31 Thomas: And they hate the social safety net

0:08:32 Bryan: Yeah. So two components. Space is the same everywhere, and all forces are conservative, things don't move except in response to a force. And you put those together, you have conservation of momentum. And it turns out conservation of moment is very closely tied to Newton's third law. In fact, the third law is one of the ways that momentum is conserved. It's basically that when a force acts on one thing, that thing will change momentum. And then that change has to be compensated for by the opposite change in something else. So this is when you pat the cat, you push down, the cat has to push up on you against your hand. So the momentum change balances out.

0:08:32 Thomas: Got

0:09:21 Bryan: And so if sperm were to violate, violate Newton's third law, then well, let's just go back to logical analysis, what would have to be true for sperm to be able to violate the third law?

0:09:35 Thomas: It. Don't know what would be true if it was violent, I'm not even sure in what sense this is meant,

0:09:39 Bryan: Well, so let's just think about in it, basic logic, if you have a statement of the form, if A then B, that is, in all universes versus where A is true, B is also true. So here we have, space the same everywhere, etc., then Newton's third law. Now, we're flipping this. We're saying, okay, what if not Newton's third law?

0:09:46 Thomas: Okay. Okay. Hmm. Okay?

0:10:03 Bryan: Then you can take that original statement, flip it around, reverse it, also also known as the Missy Elliott transformation, and get what's called the contrapositive of it. So if not A, then not B, which is equally true to the original statement.

0:10:20 Thomas: Oh, it is. Okay, I wasn't sure if it was one of those ones where it's like, well, there could be a different cause or something, you

0:10:22 Bryan: Yeah. Yeah. Well, let's go with a simpler. Let's say if an animal is a raven, it is a bird. So the ways you can modify that.

0:10:31 Thomas: Oh, so if it's not a bird, then you know it's NOT a raven? Okay. Gotcha.

0:10:35 Bryan: Yeah. Yeah, and that one's always true, but there are also two others which aren't always true. There's the inverse, which is where you flip either side of it, so if it's not a raven, it's Not-a-Bird. Well, yeah, that doesn't work. You know, it might be true. It might be a bat, or it might not be true, it may be a robin. And then there's the converse, which you keep it the the same, but flip the order. If it's a bird, it's a raven.

0:10:38 Thomas: Sure. Oh, yeah. That's the one that doesn't work out. Yeah.

0:11:05 Bryan: And, well, you have the Same examples here. It could be a raiven, but it could be a robin. But the contrapositive, by both flipping and reversing, you guarantee that it's always true. You can't find something that is not a raven that is also Or sorry, no, not a bird. You can't find something that is not a bird that is not a raven.

0:11:04 Thomas: All right. Also not true.

0:11:23 Thomas: Wait. No. No. Not No, I think it's not a bird. But is a Raven. Yeah, that's what it is.

0:11:30 Bryan: Yeah, that's it. Okay. Okay.

0:11:32 Thomas: We nailed it. Got it. Okay. So how does that apply here? To our cum. Sorry.

0:11:34 Bryan: Yeah. So so If we have not Newton's third law, then one of the things that lead up into it must be wrong. So remember, our argument is if space is the same everywhere and principle of stationary, stationary action, than Newton's third law. So we flip it, we reverse it. We get not Newton's third law, therefore not space is the same everywhere and principle of stationary action. So you can also distribute a not over an and. Not and, parentheses, A and B, is has the same meaning as not A or not B. So it means if we don't have Newton's third law, one of the following is true: either space isn't the same everywhere, or we don't have the principal stationary acts.

0:11:46 Thomas: Okay. Okay.

0:12:26 Thomas: Right. Could be both of

0:12:27 Bryan: Could be both.

0:12:27 Thomas: Them? Okay. Okay. Interesting.

0:12:30 Bryan: So in this case, space not being the same everywhere, because sperm are weird, that would be a pretty big statement, and principle of stationary action, uh, this is something that, yeah, it's complicated name and it's a complicated thing, but remember the two things I said lead up to it, basically conservative forces, which in a way is closely related to conservation of energy.

0:12:54 Thomas: Mm-hmm.

0:12:54 Bryan: That the energy you put into something, you get out, and they're also, there's also only one way, um, through the universe. You can't take a shortcut. It's also, it's like the no portals theorem. Yeah, portals break the principle of stationary action, but that doesn't mean they can't exist. They just mean if they do, then we don't have all these other things that result from them.

0:13:05 Thomas: Oh.

0:13:16 Thomas: Oh, okay. Thank God.

0:13:18 Bryan: There's still a chance we could, we could find wormholes, not a good chance, but there's a chance. So one of those must be false if Newton's third law is broken, even if it's a ridiculously minor, uh, scenario that happens only in one specific interaction that almost never occurs in reality. If it can ever be violated, then that means that one of those building blocks that build up to that law must not be true. So if this article is telling the truth, then basically some of the fundamental aspects of what we think we know about physics are wrong.

0:13:58 Thomas: And to think. We all discovered it because someone's ejaculate or. Crazy. But what did the article actually say? We haven't exactly told people.

0:14:00 Bryan: Yeah. Okay, yeah, I think that's kind of worth thinking about. That's a good first wave of analysis is when thinking of a claim like this, okay, what would it actually mean if what it says is true, and here it basically breaks all the physics as we know it. So maybe all of physics is wrong, but Okay, that's the right way to go. So, if we look into the article, let me just skim down until I find a pull-out quote here.

0:14:16 Thomas: Yeah.

0:14:25 Thomas: Consider me skeptical, Brian. I see what you're doing with these puns.

0:14:36 Bryan: Okay. So, basically, I'll just summarize what the article says. Says, that sperm cells move around because they have a long tail called a flagellum, which wiggles around in order to propel it. It's basically a miniature propeller. The way they work, let me quote from the article, they do so in a non-reciprocal way, meaning they don't provoke an equal and opposite response from their surroundings and therefore flout Newton's Third Law. So that's what the article says. So the article is still saying it floats Newton's third law, and there isn't really any clarification. They're not saying, well, in a sense, but not really. No, the article saying they flout Newton's 3rd law. Talk a bit more, but it doesn't really give you a good explanation of it. So this is the point. Okay, they're still making this claim. Well, this article is written by a journalist who's talked to the scientists. Hopefully they've talked to The Scientist behind it.

0:15:19 Thomas: Wow. Yeah. But have they listened to the scientists, though? They may have talked to them.

0:15:38 Bryan: Yeah, yeah, Yeah. So it's possible the journalist got something wrong, or they let their instincts better get of them and tried to puff it up to something more than it was really saying. So journalist's article does have a link to the scientific publication. They don't always, but you can find it if you search the author's name. Google Scholar is a good way to do that. There's also a site called arXiv. That's A-R-X-I-V dot org, which hosts preprints of many scientific papers.

0:16:09 Thomas: Hmm. Note to editor Lydia and I for later.

0:16:16 Bryan: This is a good one. I'll give you a link. I've prepared a show notes for this, which you can link, which will have This links to Google Scholar and arXiv, and arXiv has preprints, which anyone can see without paying money. Um, this one, it looks like it's been made open access. Um, it's a recent paper and there's been a movement, uh, for a lot of, in a lot countries recently, to push, scientists to make everything open access by default.

0:16:41 Bryan: So A For people who want to stay ethical, definitely do not go to a site called SciHub. That's S-C-I-H-U-B.

0:16:21 Thomas: Nice. Yeah, that would be nice. Sure.

0:16:50 Bryan: Do not search that up. I mean, even if you were to search it up, you might have a bit of trouble finding it on Google, but Wikipedia directly links to it. So don't go to the Wikipedia article on Sci-Hub to find out where it is.

0:16:52 Thomas: Good good safety tips. Internet safety.

0:17:04 Bryan: Yeah, OK. So we're at the article. This is modern enough that it's open access. We don't have to deal with all of that crap and can just read it. They've got an HTML version right here, or you can download a PDF what does the article say?

0:17:20 Thomas: And are there any pictures? Sorry.

0:17:23 Bryan: Yes. So, the title here, "Odd Elastohydrodynamics, Non-Reciprocal Living Matter in a Viscous Fluid." It okay if you're not a scientist, you might have, uh, taken away the words "odd" in "up" something like that

0:17:37 Thomas: Yeah. I think I know what viscous means. Yeah, I know viscosity. Yeah. It means you got to drink more water. Brian is a professional, everyone.

0:17:42 Bryan: There we go but yeah okay no actually you want your semen you want your seman to be viscous I don't know why that's a question for the biologists, but yes, semen is supposed to be viscous. And that's where sperm swim in. I'm not sure why it needs to be. That's question for the biologists.

0:17:51 Thomas: Oh, is that the one I always reverse?

0:18:02 Thomas: More liquidy or less liquidy? Wait, now maybe I forget what that, right, right. That's what I thought. Okay. But you don't want the, you know, you don'T too much.

0:18:05 Bryan: Less liquidy. So more viscous is like honey or ketchup and less viscous like pure water.

0:18:17 Bryan: And in fact, that's kind of the issue that they're talking about here is that the more viscus the fluid is, the harder it is to swim through it. Like, just imagine trying to swim in honey.

0:18:26 Thomas: Right. Hmm. Sounds delicious.

0:18:29 Bryan: It resists your movement a lot more and you tend to lose a lot of extra energy. So the kind solution here, they say, is this odd elastohydrodynamics, which is mean by that we'll get into in the article. But that's actually where they bury all the stuff about Newton's third law breaking and stuff, supposedly. But okay, you're reading this. And the course of action we've gone through, we've gotten through the article, seems to make the same claim. Okay, we go to the original publication, title probably doesn't make any sense to us, so next is to read the abstract, which is your next best chance at making some sense of

0:18:29 Thomas: Yeah. Hmm, also known as the only part I usually ever read.

0:19:11 Bryan: It. Order of operations is title then abstract then introduction, figures, and conclusions, and and then maybe the rest of the article.

0:19:20 Thomas: Gotcha.

0:19:21 Bryan: So we're on the abstract now, Motility is a fundamental feature of living matter encompassing single cells and collective behavior. Such living systems are characterized by non-conservativity of energy and a large diversity of spatio-temporal patterns. Patterns. Thus, fundamental physical principles to formulate their behavior are not yet fully understood. This study explores a violation of Newton's third law in modal active agents by considering non-reciprocal mechanical interactions known as odd elasticity. By extending the description of odd elasticity to a nonlinear regime, we present a general framework for the swimming dynamics of active elastic materials in low Reynolds number fluids, such as wave-like patterns observed in eukaryotic cilia and flagella.

0:20:09 Bryan: We investigate the non-local interactions within a swimmer using generalized material elasticity and apply these concepts to biological flagellar motion. Through simple solvable models and the analysis of chlamydomonas flagello waveforms and experimental data for human sperm, we demonstrate the wide applicability of a non-legal and non-reciprocal description of internal interactions within living materials in viscous fluids, offering a unified framework for active and living matter physics. Okay, so now it's 100% clear, right?

0:20:22 Thomas: Ooh, it's got chlamydia. Chlamydia.

0:20:42 Thomas: Yeah, absolutely, I get it. It sounds like some dude named Reynolds who comes a lot has chlamydia, and also, um, it doesn't make any sense that given how viscous the fluid is that it's able to still go quickly. Is that something like what we're talking? We ignore the jokes, but like, Is that the problem?

0:20:57 Bryan: Not viscous fluid, which in science terms they call a low Reynolds number fluid, Reynolds number is just a way of measuring how viscous it is. You lose energy too much to the environment through normal elastic motion. But in this so-called odd elasticity of sperm tails, you don't lose as much and you can actually get into kind of a steady state of the tail spinning around. And as it's spinning around, propelling the sperm forward.

0:21:05 Thomas: Yeah. Okay. Okay.

0:21:31 Thomas: But I kind of think that's what I was saying. Like, it's the thing that's happening. The violation that's happening is it's able to still go fast, even though you got the super viscous thing. Is

0:21:39 Bryan: Okay. Yeah, now okay, what is it going on with the violations of Newton's law? So let's pull out that one sentence again. This study explores a violation of Newton third law in modal active agents by considering non-reciprocal mechanical interactions known as odd elasticity. So that sentence again, it's just saying there's a violation of Newton's third law, so the authors are putting it in the abstract. There's the violation, they aren't qualifying it in any way. They're saying the mechanism through which it's violated is this non-reciprocal mechanical interactions called odd elasticity. Okay, we'll Figure out what that is, but they do claimed there's a violation. So, unfortunately, we're going to have to go a step further and read the introduction, conclusion, and figures.

0:21:56 Thomas: Hmm. Mm hmm. Mm-hmm, got to keep reading. Damn it. I'm always hoping we're going to get bailed out. Well, maybe it just violated like the trust of Newton's third law. You know, maybe it's not violate the personal space of it. Maybe it didn't actually like break it.

0:22:28 Bryan: Yeah. Yeah. Yeah, there you go. So, pulling up the article. We don't have read to the whole introduction and conclusions or it's too long. I'm just going to do it. Control F Newton. Newton. Okay, Newton shows up twice in the article, once in the abstract, we've already read that, and once in The Introduction. So this right now is a bit of a, maybe a yellow flag, that they're only talking about Newton's Third Law in The introduction. You think if Newton's third law is violated, you're going to mention it a lot.

0:23:03 Thomas: Yeah, that's going to be like title, body, main, everything. Yeah, you're going to mention it.

0:23:09 Bryan: Yeah, it okay. Shows up in the introduction in the first paragraph, let's read the sentence where it shows up. Crucial feature of these systems is that interactivity units convert energy into mechanical forces. In turn, Newton's third law may be violated when we regard it as an open system with its mechanical energy being injected from microscopic active units. We've come all all this way. And now we find out that they were hiding this little bit from us.

0:23:38 Thomas: So like if you look at it a different way than it is, then what is it? I didn't understand.

0:23:44 Bryan: Well, yeah, when we regard it as an open system. So an open system means that there are interactions with things that you aren't considered part of the system. So this would be like, go back to the original example, you pat a cat, you feel the reactive force on your hand, but let's say the system, we're just regarding your hand. We're only looking at the forces on your head and look, oh, there's this odd unbalanced force in the shape of a cat's head. That's a violation of Newton's third law. That shouldn't be happening.

0:23:55 Thomas: Ah, but if it's that dumb, though, like that's crazy to even put in your paper. Isn't that always going to Be True? Like no matter what we're talking about. Yeah, well, if we pretend part of this is like different than it is, than what boy, it sure looks weird. What is that adding?

0:24:27 Bryan: Yeah. So in this case, think I it's a bit more reasonable to Do this as kind of looking at the system as the fluid plus elastic sperm particles. And the part that's relevant that impacts it is the internal energy of the sperm. So sperm have, you know, that if you go back to your middle school, high school biology, the parts of the cell, the mitochondria of the cells, as the powerhouse of it, that causes things to happen, and cells with flagella usually a mitochondria lined up around where the it connects to the flagellum to move it about in the ways that it wants

0:24:32 Thomas: Okay. Hmm. Freaking

0:25:11 Bryan: To Yeah, it's it's amazing how complicated things are even at these scales.

0:25:11 Thomas: Crazy. It really is. Yeah.

0:25:16 Bryan: Yeah, so they've got multiple mitochondria lined up to wiggle the tail, and so we zoom out back to the larger scale, you can either try to model the whole system including these mitochondria in the cell trying to wiggle the tail, or you can do an approximation of it, which which you hope is good enough in order to model decently how things behave.

0:25:46 Bryan: And I basically, assume a spherical sperm and Newton's third law is being broken, and you actually get a decent approximation of what's really going on. And they basically say that way they formulated it, treating this as an open system with a Newton's third law violation within it, which is caused by the fact that the mitochondria are deliberately wiggling the sperm's tail, is the easiest way to model it that actually works reasonably well. And it's actually, you end up with a surprisingly simple model, relatively speaking, for how the sperm's tail will twirl in a consistent manner over time. Just have to do that by slightly tweaking how physicists normally do calculations regarding elasticity and turn it into this new thing they call odd elasticity.

0:25:46 Thomas: Oh, is this assumed spherical sperm? A... Okay. Okay.

0:26:46 Thomas: Okay. For So, the sake of calculating this, let, it is easier if we just, like. Bend Newton's Third Law a little bit and it makes this calculation easier. Okay, okay, I thought it was. Cause papers that allegedly, you know, phenomenon or whatever that allegedly break some sort of law is a great genre for the show for the, especially, uh, the Dr. Bryan Gillis episodes. And there was one involving the, what was it? The, was it the magnetars? And it was like, Hey, because um, this violates the law or seems to violate laws, we need to change our assumptions about what's going on here. We need to figure that out. And this sounds, I was putting it in those terms at first, but this sounds like, hey, no, we found a great way to like approximate something. And it involves like, just on paper breaking a law here because it makes it easier to calculate.

0:26:51 Bryan: Yeah. Yeah. Exactly. Yeah.

0:27:28 Bryan: Yeah, that's pretty much it. So that part, I get what they're doing there but when we zoom out a bit and go to what they say in the abstract where, let's read that sentence again. This study explores a violation of Newton's third law in modal active agents by considering non-reciprocal mechanical interactions known as odd elasticity. Realisticity. So for people who only read the abstract, which are going to be a good fraction of the people who look at this paper, they're not going to see the explanation that it's not a real violation. It's just this is the easiest way to calculate things.

0:28:02 Thomas: Yeah. Yeah.

0:28:03 Bryan: And so I'm not going to blame the journalists on this one. They were reading the abstract. I think blame the goes here on the authors of this paper. They're engaging in what I think is a legal term is a puffery. They are trying to build it up. And in or technically not lying or you can kind of imply so reality can be shoehorned into what they say. But if you you listen to what they say, it implies something a lot different than what's actually going on.

0:28:18 Thomas: Ah, yes. Yeah, yeah.

0:28:33 Thomas: Yeah. They're like, I can't believe it. Cum is not selling enough. We thought that just studying that would get eyeballs on it, but it's not. So let's also add in a pretend violation of Newton's third law. Okay. And that, you know what? We're talking about it. Any PR is good PR. And I don't know.

0:28:45 Bryan: Yeah. So let's talk a bit about, what's you actually going On here. What is the supposed third law violation? Do that, let's have a look at the paper, see if they have any useful figures for us. So So, Thomas, I'll send you a link. This will be in the show notes. You can find a link to the paper.

0:29:10 Thomas: I get to try to have my computer do anything else while opening a PDF, which is somehow impossible. PDFs, technology still not figured out. It's hardest the thing a computer can do is have a PDF open. What page am I going to?

0:29:21 Bryan: Well, let's start on page two, where we have a nice color figure.

0:29:26 Thomas: Right. Page two. That blob? That blue blob? Okay. Jeez. I think that person needs to go to the doctor if it looks like that.

0:29:29 Bryan: Yeah. Yeah. So, if your sperm looks like a blue blob with wiggles and no tail, yeah, go see a doctor.

0:29:42 Thomas: It's like a crime scene. Someone killed the sperm.

0:29:46 Bryan: Yeah, it's basically just a splat. So I think what they're trying to do here is just show a mock-up illustration of a generic microswimmer, as they call it, which is their way of representing some elastic thing, probably like a single-celled organism, a bacteria, or whatever, that responds.

0:29:48 Thomas: Yeah. Okay.

0:30:10 Thomas: All right, or whatever. Yeah.

0:30:13 Bryan: Yeah. Well, it could be like protist. There are other types. Yeah. They show within it. So they've got these little yellow circles connected by a zigzag. So the zigzag pattern is used in diagrams to refer to a spring-like force. So we've basically got a bunch of white dots, which are just like elements of mass connected by springs and this

0:30:15 Thomas: Sure. Sure. Yeah. Okay. Knew it. Sperm is entirely composed of little springs. It's just little gears and springs in there. I knew it. Blowing the lid off this thing.

0:30:40 Bryan: Yeah. So this is the way scientists, uh, like to model, elastic materials as individual components connected by strings, so you can kind of imagine this, like, you've all seen a spring or are played with the slinky and you know how if you press in on it, it'll press out against you, you pull out on it, pulls in against you, and so if you put enough of these together form up a grid-like pattern, you can get a wobbly material made out of these springs

0:30:48 Thomas: Ah, okay. Yeah. It is really interesting to try to consider modeling, like, jokes aside, how hard it must be to try to model things like this, like, well, it's a, it's viscous springy fluid and you're like, all right, we're trying to calculate it based on like assume little dots and springs inside, but it makes sense because you can't, it's gonna, the force is gonna act on it in a way, and there's gonna be, and it's going to travel through the liquid, you know, and be delayed in a way and then come out the other side maybe, and it must be really challenging to try to scientifically model that, yeah.

0:31:45 Bryan: And This way with the springs is probably the best way we have. So let's take an example that's a bit more tractable than a random blue blob. Let's say we have a jelly cube. So y'all know a cube has, made you out of squares, has six faces on it and has eight corners.

So the way we can model a cube of jelly is, say, we have one point of mass at each of those eight corners and each edge is a spring, spring, so then we have 12 springs for each of the edges connecting it up and we have this, basically, a spring cube, and that will to some extent model the wobbliness of jelly if you press in on it, it'll spring back, like, if you think, if you just press in on the top, this will be the simplest way, the four side edge springs will all be pressed down and they'll press, push, push it back up and it'll just bounce back and you know, you can also push the whole thing, like, the top of it to one side, the bottom to another, and it will wobble back as the, they try to, restore to the original position, so, you this method can do a decent job at simulating this, thing this is often called soft body physics when

0:31:58 Thomas: Yeah. Mm-hmm. Yeah. Yeah, Mm-hmm. Oh,

0:33:04 Bryan: People use it to simulate things in, uh, video games or movie CGI which is, becoming more and more necessary as graphics advance, for, for a while, uh, people will get by with only hard body physics with just like an individual thing with a shape and you can't deform it, but now we want things to be able to deform a lot, and to do that you need to do this type of thing with, it's much more complicated, like, instead of having one object, say it's a cube, you now have to have, okay, eight objects, each of these objects is connected to three of the others with the spring force, and model them all, yeah.

0:33:10 Thomas: Yeah. Right. Yeah yeah. Yeah

0:33:44 Bryan: It's a mess.

0:33:45 Thomas: I'm really like We're so spoiled. Those of us who only took high school, well, I actually took college physics too, but, but, basic physics, we're so spoiled, we always get, like, well, you know, just assume it's like a point, you know, like a cannonball, and you just, the center, you know, use that for calculations, ignore air resistance, ignore all that, and it's like, yeah, if you're trying to actually model a lot of this stuff, it's really complex to try to figure out what's going on at all points in this gelatinous cube even. So, okay, yeah. That must be really interesting.

0:33:46 Bryan: Yeah. Yeah Yeah.

0:34:11 Thomas: I see why we're studying sperm now. Okay. I get it.

0:34:13 Bryan: And the thing is, sperm are even more complicated than this because they're, are living. They have mitochondria inside, which can convert fuel into energy, and they have some amount of intentionality to what they do. They don't have a full intelligence, but there's a deliberate response to their environment, which has been evolutionarily set up to achieve a specific end. So what they do in response to the environment isn't random.

0:34:20 Thomas: Yeah. Mm-hmm.

0:34:42 Thomas: Mm-mm. Yeah.

0:34:46 Bryan: So when you put these together, you get what they call odd elasticity, which is when you deform the sperm in a certain way, it will act in a sort of predictable way in response. And this action, by the additional energy created within it, will be in addition to whatever normal restorative force would occur just by Newton's third law reaction on its own. So this okay, let's go to cat physics again. You've got an unhappy cat. If you try to pat an unhappy kat, in addition to the standard reactive force on its head, you might get clawed.

0:35:27 Thomas: Claws. Claws are coming out.

0:35:29 Bryan: Yeah, so when you have living things, you get reactions beyond the standard third laws because they do things in response to actions. So an unhappy cat will reliably scratch you. A sperm that you stretch out, well, it's not as complicated as scratching, but it will cause its own motion in response to its tail being deformed in a certain way, yeah.

0:35:52 Thomas: Gotcha.

0:35:52 Bryan: And so the way they choose to model this is, you instead of this kind of second order effect, they argue that they can just model this using the normal um elasticity calculations of soft body or elastic body physics, but modifying a bit it a bit in a way that breaks the Newton's third law assumption. So one the of key ways Newton's third law plays into this is that there's a reciprocal relationship, that the amount of force it takes to move an elastic body from one position to another is the same as the force applied by that body once it's moved into that position. So that is, it balances out.

0:36:38 Bryan: If you compress a spring, the spring will be pressing back on you exactly as much as you're pressing in on it. We've said before, this isn't true with living creatures, because if you press down on the head of an unhappy cat, yeah, you're going to get force up from the head, but you're also going to get force up from the claws. So you're going to Get a Bit More Than You Bargain For.

0:36:45 Thomas: Okay.

0:37:01 Thomas: Yeah. And you'll get a... Give you whatever that is, like that little gobble gobble almost. That's what my cats do. They're just like, I've had a bad cat day. Don't mess with me.

0:37:03 Bryan: Yeah. Yeah, that too.

0:37:15 Bryan: And sperm do this too. They don't have claws. If your sperm have claws, see a doctor. But they do want to move their tail. And in particular, they want to rotate their tail and, you know, so this paper gets into a lot of details here, and I haven't figured out all the details of it because, you know, Thomas, I'm going to share a secret with you.

0:37:20 Thomas: Yikes.

0:37:36 Thomas: You're not a cum scientist. Yeah.

0:37:36 Bryan: Yeah, astrophysicists don't tend to deal with a lot of liquids.

0:37:42 Thomas: Hey, sometimes you discover a pool of semen on a plant. No, you got water on plants, but it's usually frozen. Not often liquid water on, on stuff, huh?

0:37:43 Bryan: Yeah, no. Some will deal with like the indicators of liquid, but fluid dynamics, Well, you'll have gases for fluid dynamics but not liquids. Woods, there's no viscosity. And basically anything we deal with. Uh, so the extent I went into this is, um, I focused on the sperm because there is a lot of sperm in space. Um, they don't want you to know about it, but I am breaking it to you right now.

0:37:55 Thomas: Yeah. Right, right, right. Oh, I have heard of panspermia.

0:38:13 Bryan: Yeah, there you go.

0:38:15 Thomas: I thought that was a really good joke. Damn. All right.

0:38:17 Bryan: Yeah. No, it is, it's actually, uh, quite literal, because the the sperm in panspermia is exactly sperm, is what we're talking about, it's seeding things from space. But yeah, space sperm.

0:38:27 Thomas: Yeah. Space sperm. Okay.

0:38:29 Bryan: Well, anyways, let's look down in the paper, go a couple pages to page four, and at the top left, they have a couple more illustrations. What they're showing here is just basically a couple ways of illustrating that over time, the tail of a sperm goes in a somewhat circular motion. It's actually rather complicated the way it twists around. So if you look at panel C of this, they show a superimposed image of snapshots of the sperm and its tail over time.

0:38:51 Thomas: Oh, yeah.

0:39:04 Thomas: Oh. It's very Matrix 2 and 3, actually. It's like squid-like almost, right? It's kind of, yeah, interesting.

0:39:10 Bryan: Yeah, yeah, Yeah, now keep in mind the sperm only has one tail, this is many shots of the same sperm.

0:39:17 Thomas: Okay, oh, they don't swim in teams like that?

0:39:17 Bryan: Yeah. No, just one sperm that's been overly photographed and they smushed all the photographs together.

0:39:26 Thomas: Yeah. Boy, boy, it's really interesting. It's almost like a sine wave type thing. Yeah. Very interesting to try to figure out how to calculate some of this stuff.

0:39:26 Bryan: Yeah. Yeah, and and so what they're looking at is, let's look at the elasticity of the tail, so they modeled the tail as a bunch of individual points, which are all connected to each other. And any two points can be moved apart from each other with a spring-like force, essentially. So you've got long a chain of springs to model the tail. And they've said is that in the simple case where you assume the Newtonian approximation, you can't keep the tail wiggling. It loses energy to the environment way too quickly.

0:40:07 Bryan: But if you model it with allowing these violations, then you can keep it going. It will enter this steady state, which is what they show. And I think panel B is showing this. So panel B shows many points of where it is. You can imagine that they're tracking the tip of the sperm's tail over time. They aren't really doing this, but imagine they are. And like they take snapshots over time, they take the X position of the tip and the Y position of tip and plot them. And then over time they work their way around a circle. So you say, oh, it's just, it just keeps following the same path over and over. It doesn't just go on this one path,

0:40:05 Thomas: Hmm. Oh, wow. Yeah, yeah. Wow. Is that not, you're saying that's not real though? Because it forms like a perfect circle almost. It is crazy.

0:40:58 Bryan: It's not tracking the tip. It's tracking some more abstract quantities. But what they're saying is the fact that it's a perfect circle means that these abstract quantities are in a repeated pattern, that it keeps following the same path of these, what they call PCA modes, which are very abstract ways of characterizing the whole motion of the sperm. But in the end, And it does result in the whole tail entering in a sort of periodic motion over time.

0:41:11 Thomas: Yeah okay.

0:41:30 Thomas: Yeah really interesting, me of like Spirograph. Do you remember those? It's like an emergent pattern, a little bit, from another pattern, you know.

0:41:34 Bryan: Yeah, Yeah, they're looking for these patterns. And in fact, these modes aren't things you can easily describe. These are ones that they had to calculate. Once they notice that the motion is periodic, they can look at it and find, okay, what are the the modes that are repeating over time, and they've shown that there are actually many modes, not just the two that are plotted here. It's just limited to two because paper is two-dimensional, but there are many repeating modes showing how the tail wiggles over time. And they've showed that, look, if you look at these two over time, they go into this repeating pattern.

This extends to the whole tail of the sperm, goes in a repeating pattern over time, and this works very well, and all they had to do was modify the elasticity matrix of the tail, breaking the third law assumption, but saying, yeah, yeah, we understand where that's coming from, it's coming from the mitochondria in the cell powering it in a specific way, but all we we care about for modeling the physics is we've just got a different matrix to calculate. So they can do all the same physics calculations as before. They don't need to make the simulation any more complex.

0:41:54 Thomas: Yeah interesting So it's a very known and intentional violation of uh Newton's laws and not something that's been discovered per se or we don't need to call the space force police, everything's under control, nothing to see here.

0:42:59 Bryan: Yeah. Yeah, yeah, yeah. So boiling it down the sperm are not actually violating Newton's third law. Nothing here is. It's just that there's a way you can model the motion of a sperm's tail, which includes a Newton's third law violation a known source for it and works very well for modeling it. And honestly, we do this all the time in physics. Like in high school physics, you've probably done examples of throwing a ball in the air. And When you do this, you say, okay, gravity acts on the ball. We're going to say it's just an acceleration, 9.8 meters per second squared or whatever it is in imperial units good

0:43:42 Thomas: No.

0:43:53 Thomas: We do, we actually do use that here, we use 9.8 meters per second, the physics classroom is the lone bastion of communist metric uh systems in in America.

0:44:02 Bryan: Good Okay.

0:44:03 Thomas: Like they don't make them do feet.

0:44:05 Bryan: Good, good.

0:44:06 Thomas: Ron DeSantis passes something, I'm actually surprised they haven't gone after that, you know, with the critical race theory. Also, I heard they're using meters in physics class, and then you have to do everything. That would be horrible.

0:44:06 Bryan: Thomas.

0:44:16 Bryan: I don't want to scare you, but they're actually doing that in the UK, they're trying very hard to find some way they can say Brexit gave the UK benefits, and the only thing they've gotten is, okay, we could use imperial units for stuff, we can start selling beer by the pint again.

0:44:19 Thomas: No.

0:44:33 Thomas: Oh, God, that's so. Pathetic. OK, yeah. All right. Nine point. So you're saying we use nine point eight meters per second squared. Yeah. Where's the violation coming from?

0:44:35 Bryan: We yeah, yeah well Violation is we've only got the one force on the ball, we're not modeling any reactive force from that, and that's because the system we're looking at is only the ball, and we ignore the fact that gravity is caused by Earth, and so in reality you get the exact force on either end, Earth pulls the ball down, the ball pulls uh the earth up by exactly the same force, now the earth is so much more massive that you don't notice the acceleration, because it's you pretty hard to move something that big when, when we want to do calculations, we just simplify. Oh, okay, okay. This is an open system. We acknowledge there are things outside of the system that impact it. Newton's third law isn't strictly followed within this system.

0:44:46 Thomas: Yeah. Mm hmm. Mm hm. Wow.

0:45:28 Bryan: Oh, you might be picking up some cat meals.

0:45:28 Thomas: You got a mad cat. Yeah. Yeah,

0:45:30 Bryan: Yeah, Yeah, he's mad the door is closed, I think. Closing doors violates cat laws. And this one is a violation, trust me.

0:45:30 Thomas: Cat law. Yeah Oh for sure cats have a code, you know, you have they rules They're like, hey, this is against the rules, sir, sir And then they meow at you for the entire time. It's interesting

0:45:40 Bryan: Yeah, I closed the door to try to cut down on sound, but equal and opposite reaction, more sound is created.

0:45:54 Thomas: Yeah Yep. Yeah it's a real gamble. It'll buy you a few minutes until the cat wisens up Okay, so you're saying this is essentially no different than, it's sort of what I mentioned earlier too with the wind resistance, like there's often, you just, for the sake of being able to do a calculation, if you really had to take into account every friggin' variable, to do even the most basic physics calculation would be extremely difficult.

0:46:00 Bryan: Yeah, Yeah, Exactly.

0:46:17 Thomas: Called. I mean, wind resistance, elasticities, the, the furthermore, even, even if you were trying to do that, like the, uh, the slight differences in, in, uh imperfections in like the shapes of the thing you're talking about, the surface, all this stuff. And you're saying this quote unquote violation is no no different than just a constraint of doing a calculation or maybe a, good way of doing a calculation that you're doing on purpose. Us.

0:46:39 Bryan: It's just like the case of throwing a projectile. Yes, properly you should do it by modeling the Earth's motion as well, and you You shouldn't treat the Earth as flat. You should treat the Earth as a sphere. But practically speaking, most of the time, it's simpler and good enough to ignore all of that. And it makes things a lot easier to handle. And that's what's happening with the sperm here is that when you ignore the requirement for Newton's third law and allow this, what they call odd elasticity, which is just a different way of modeling elasticity that doesn't have that constraint and allows you non-equal reactive forces, then you can model things pretty well increasing the computational overhead or difficulty of

0:46:52 Thomas: Right. Mm hmm. Oh, you

0:47:31 Bryan: It significantly at all.

0:47:32 Thomas: Could have said computational load, Brian. You could have said computational node and So don't worry. The cum is not violating physics. It's just a bit of a clickbait thing, but really interesting to take us through that. I appreciate that. All jokes aside, it is really interesting trying to think about how they model these things. And, I think the, this time-space continuum though, no tears, we're all good. Everything's healthy.

0:47:34 Bryan: Oh, yeah, there you go. Sorry.

0:47:53 Bryan: Yep. I think we're safe. Well, everything's healthy except my cat right now. He really wants to be let in. So I

0:48:00 Thomas: Well, for the sake of your cat, we'll call it Dr. Bryan Gillis. Thank you so much as always for joining us. Anything you want to send listeners see any plugs you want to make?

0:48:02 Bryan: Yeah. Let's see. I can't really think of anything Don't Commit Genocide. I used to think that one went without saying, but I think it needs to be said don't commit genocide

0:48:11 Thomas: That's a good one. Apparently not. Yeah, yeah, yeah. That's good tip. Good tip there. Love it. Thank you so much. And we'll see you again very soon.

0:48:17 Bryan: Yeah okay thank you everyone for listening