SIO353: A General Episode on Special Relativity!

Transcript

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

0:00:16 Thomas: And welcome to Serious Inquiries Only, this is episode 353, and I'm Thomas Smith, and this is a part two, so make sure you listen to the last one, because that's where we started this conversation, and now we're going to get to the second part, which is more in depth, a bit longer, and it's about relativity, it's time travel, it about time and space and light and all this good stuff, super fascinating, I love it so much.

I will say, after, after editing and kind of hearing this a second or 50th time, depending on how you count editing, um, there's some stuff in here I still didn't fully grok, so I'm gonna say maybe if you have questions, you know, post them on the Patreon or on the wherever you, I guess, can post them, post them where you see the episode, um, and maybe we can try more to have, have Ryan further help us understand this, or maybe it's just me and you all just 100% understand it, and that's cool, that works too.

Also, quick note, and I suppose this is for patrons because they're hearing this right away. But as I'm recording, it's announced that Trump will be indicted. That is major. And I'm going to get on with Matt as soon as I can to do a response on that because that is huge news. Absolutely huge. Looking forward to celebrating. But in the meantime, let's learn a bunch of really cool stuff about astrophysics and relativity and whatnot. Here we go.

0:01:31 Bryan: Think for this, let's start out with a bit of history about the speed of light, come at it from the same perspective that humanity does. So first, has figured out that light is a wave. It's in particular a wave of electromagnetism, that basically you get alternating electric fields and magnetic where the creation of one and then the destruction of that spurs the creation and destruction of the other, and they basically leapfrog each other, you get an electric field going up and down and a magnetic field left and right, one causing the other, and then it all moving forward, and so at the smallest scale possible is one photon of light, and so this was figured out, uh, in uh, the 1800s.

0:02:05 Thomas: Huh?

0:02:16 Thomas: Yeah. Yeah. How the heck were they, they figuring this crap out in the 1800s? I don't even, that's impossible.

0:02:16 Bryan: Um, I think one thing to remember is that humans were always as smart as present day humans. We haven't evolved to be smarter. We've just built new tools. So you've got a lot of really clever humans working with, you know, pen and paper, log tables. They figure out very clever things to do all of this. They don't need computers. They can do thought experiments. They can do some pretty good real world experiments to figure out a lot lot of this. And this is when we're getting into that pioneering work on electricity and magnetism, they figured out, okay, light is an electromagnetic wave and work like any other wave, and right? So, they start thinking about how other waves work. So, you can think of water waves or sound

0:02:20 Thomas: Yeah yeah You know, sound waves

0:03:04 Bryan: Waves and other wave travels through a medium that's basically the thing that holds the wave, so, yeah, in water waves, obviously water, yeah, it's air or walls or whatever, and then for light, well, what's the medium, and they, well, it seems to be able to go through empty space, but it must go through some medium, so there must be some medium. And they use the term ether to describe this, ether being a reference to what's considered one of the fundamental elements of reality in some teachings, not the four Greek classical elements, but there are other ones that have ether as one of the fundamental element. So they say, okay, whatever light travels through, that's the ether. And then, okay.

0:03:04 Thomas: Yeah yeah right the ether, so yeah and That's so intuitive, like, I know that ends up not being true, but But I've learned a little bit about this, and I just think it's so cool, some of ancient ideas, you know, that are like, well, that's obviously, obviously terrible. But some of them, it's like, no, that's actually a pretty good idea. Like atoms, you know, like atomists are from, you know, the year zero negative, whatever, BC, something.

0:03:52 Bryan: Yeah.

0:04:05 Bryan: That was ancient Greek in BC. They were thinking about atoms. They couldn't prove it for quite a while, but

0:04:07 Thomas: Yeah, exactly. Right. And it's super cool. No. Yeah. But the idea that there must be some reference frame that's like absolute in the universe, there must Be some like base thingy that everything is sort of within is really hard. If you don't have, benefit you of very very advanced discoveries in science, that's really hard to shake as just an intuition itself, in

0:04:11 Bryan: Yeah.

0:04:32 Bryan: And they said, "Okay, well, let's try to learn about the ether." The must have some reference frame, and light travels at the speed of light through that reference frame. And now the speed of light is very large, 300 million meters per second. It's hard to measure it that accurately, so they have to come up with even more clever ways to do it.

0:04:50 Bryan: And the Ways they do are basically interference patterns, which is basically you take a ray of light, you split it into two, so where the two waves match up, then you send them across a course, bounce them back and forth a ton of time so that the actual Path is very long, then you combine them back again, and if one of those paths is very slightly different, uh, the peak of one wave will be offset from the peak of the other, and they'll add up to not being as strong a wave as if they were perfectly aligned. And so this is what they call interference.

0:04:50 Thomas: Yeah, yeah.

0:05:23 Thomas: So was the idea that they're like, hey, we'll figure out which one of these directions in the course is against the wind, essentially, like against the ether wind, you know? Like, and that will tell us kind of the directionality of this, of, I don't know, of our movement with an absolute space or whatever, within the ether.

0:05:30 Bryan: Yeah. Yeah, yeah, thinking about this, you also have to consider, is the ether a perfect still reference frame? Because at this point, they're just imagining it. Maybe the ether doesn't interact with matter at all and is is always fixed everywhere throughout the universe, or maybe the ether interacts with matter a lot, so much so that as Earth moves around the sun, it picks up a big ball of ether around it that it drags along as it goes around the Sun, or even as Earth rotates, the ether rotates with it. All they knew, that was plausible.

0:05:51 Thomas: -hmm, right. Right?

0:06:16 Bryan: And so the first step on this is, okay, let's figure out, does ether get dragged along? So in the 1850s, the scientist called Hippolyte Fizeau does an experiment where he, Hippolite, his first name is Hippoleite, last name Fizeaud.

0:06:27 Thomas: Sorry, what? That's the best name ever. I don't think we can pass, you over there. What kind of nationality is this? What is that name?

0:06:35 Bryan: Oh, Fizeaut sounds French to me. I'd have to look it up. Yeah.

0:06:40 Thomas: Oh, I love it. Okay, this is great. This is my favorite character so far.

0:06:43 Bryan: Yeah, Hippolate does not sound French though, so who knows?

0:06:46 Thomas: Yeah, I'm not good at that stuff, but that's a cool name. Just want to point that out. I'm going to name my fourth kid that. No, No, we're not having 40, but another, our next pet is named that I'm just saying, saying 1850s. They're doing this.

0:06:49 Bryan: Yeah, okay. Yeah! Yeah. Okay. Yeah, okay. That'll work. Yeah 51. 1851.

0:07:01 Thomas: Just blows my mind. First off we we are enslaving other human beings at this time. And we're like simultaneously parts of the world or parts of people are geniuses. Like that's, that's crazy. Secondly, I mean, our best method of travel is like railroads and there you know and we're like but also let's figure out the directionality of the ether or you know that's so cool to me

0:07:06 Bryan: Yep. Yeah yeah yeah. So 1851, the the first step is figuring out, is ether being pulled along by anything? And the Fizeau experiment looked into this by basically shooting rays of light through moving water and doing this interference to detect that if the paths got offset. And this ended up showing very clearly, okay, the ether is not being dragged along by any thing. So this means that it's not being dragged along by water, it's not going to be dragged around by the Earth moving around the Sun. So we can assume the ether is going to fix whatever it's doing. It might be moving fast relative to the Sun, it might be stationary, but whatever it is, the rotation of Earth around the Sun isn't going to affect that. Then the next step is to figure out, by using the fact that that Earth is rotating around the Sun. This means that there's going to be a huge change in the velocity of the Earth relative to the ether over the course of the year.

0:08:22 Thomas: Yeah.

0:08:22 Bryan: Like six months later, It's a reversed direction. And you've got a huge chance. So if you track the speed of light doing the same tricks with interference patterns over this time, you can get an idea of, you speed changing throughout this time? So this is where the experiment that most people have heard of comes in, called the Mickelson-Morley experiment. Is in 1887, a few decades later. Had ideas about how to do this. It was mostly an engineering problem to get the accuracy to a good enough level to do this. And they were finally able to do it to a convincing level by this point. And so they set up an interference machine that tracked the speed of light both the course of the day and over the course of a year to see if there was any change in it and it came out that no, there was absolutely no change.

And the only way there could be absolutely no change is if the ether was being perfectly dragged along Earth's surface, but back in 1851, Faisal said no, the ether doesn't get dragged along at all. Yeah, was stumped and it's like, okay, what, the speed of light is always the same? And there's a lot of trying to figure this out. And so what happens is, in, guy thinks, okay, let's say the speed of light is always the same. Now, we talked about reference frames in the last episode and. And the rule I gave you is switching from one to another. All you do is subtract off all the values from one. You subtract the position, you subtract the velocity, you subtract the acceleration. But if the speed of light is always the same, you can't just subtract the speed.

0:08:24 Thomas: Yeah. Mm. -hmm, yeah. Yeah. Yeah.

0:10:00 Bryan: You can't subtract the philosophy as otherwise you've changed the speed -of -light. One guy starts thinking, okay, let's change how we switch between reference frames. Let's figure out a way we can do this mathematically and the speed of light constant. So he gets down, he buckles down, writes out a ton of equations, and comes up and says, oh mathematically this actually works. We can change how we shift reference frames and keep the speed -of -light constant. It causes a lot of weird effects, or squishing space, or expanding time.

0:10:28 Thomas: We just have to change some other, other weird stuff.

0:10:30 Bryan: It's really weird. And you know that man's name Einstein was Hendrik, no, Hendrik Lorentz. Yeah, Einstein came around about 20 years later.

0:10:30 Thomas: Yeah. Was Albert Einstein? Yeah, that was a good trick. I love that. I love that, that's, that's awesome. Oh.

0:10:40 Bryan: Yeah. These things are always more complicated. I'm already, I'm giving more details than comes to the standard detail. Like, no one hears about the Fizeau experiment, even though it's critical because on its own, the Michelson-Morley experiment doesn't prove the speed of light constant. It's only in conjunction with the Fazeau experiment it does. And most people in the common understanding don't realize that Hendrick Lorenz was actually only one few people who figured out that you can change how you do transformations to allow the speed of light to remain constant. And now, Albert Einstein, he deserves a lot of credit. He's one of those people whose genius is not overhyped.

0:10:46 Thomas: Of course yeah yeah Right.

0:11:22 Bryan: He came in like a wrecking ball and upended everything and was able to convince people of this. Before then, it was just something Lorenz had written down and said, well, I suppose this works, but that's weird, weird.

0:11:33 Thomas: Okay. I see, yeah. So in some ways it's like, for those who might be familiar with like string theory a little bit, now, I can't say I understand it, but but my impression is it's a lot of math to make stuff work, but nobody is like, yep, this is the universe, right here, this one that has 15 dimensions and whatever, you know, whatever. Is it kind of like that, where Lorenz was like, all right, well, this is the math that could kind of work for that, but but

0:11:34 Bryan: Yeah. Yeah. Basically. And then Einstein came along, it would be like someone coming along today and saying, oh no, but this is how it actually works, and getting people on board, giving very clear explanations and going a bit further, uh, with it, and eventually coming up with ways it could be tested and proven, uh, be true, uh, the hard work of convincing people, even if it, it wasn't his original idea. Things are never as simple as one person acting on their own. Yeah.

0:12:00 Thomas: Yeah. Right. Yeah. That yeah That's science. Yeah Yeah, totally, god, it's so fascinating though, this is my favorite subject like of all time because Einstein had like, the, I don't know, like the rail car thought experiments, right, where it's, it's like, there's a mirror and the light and the like. And so, is it just that he was like, so if before, they at least understood mathematically what might have to happen, it's a question of him just really saying, like, here's what this really means. It means that time actually slows down, or that mass actually increases if the following things happen.

0:12:37 Bryan: Yeah. Yeah. Yeah.

0:12:54 Thomas: Is that what it is?

0:12:54 Bryan: He laid It out very clearly. And he also went back and gave a re-derivation of the equations that Lorenz had come up that was a lot more intuitive and convincing so that more people could understand it. Now, keep in mind at this time, it wasn't proven to be true. It was just that this is a way it works. This is a way it makes sense. But we don't have you know, aside from the original experiment, we don'T have any way to test that this explanation of it is right. This IS one possible explanation, but maybe it's wrong and there's something else. So eventually they were able to figure out an for it. Yeah, light around the sun, basically looking at how the paths of stars get bent during an eclipse. If you accept Einstein's explanation, there's basically a factor of two difference in how light will get bent by gravity compared to if you don't. And when measured, it turned out that the relativity explanation turned out to match the data better the non -relativity explanation.

0:13:12 Thomas: Mm hmm. Mm hmm, right.

0:13:34 Thomas: Is the light around the what is it? Yeah.

0:14:03 Thomas: And I imagine it was just it a question of when you have the like instruments sensitive enough to to do that kind of thing. Right. Because I feel like it, if I remember right, wasn't like Einstein never thought this would be able to be confirmed in his lifetime. But it, but wasn't it, wasn't that part of it confirmed at least? Or was that after he died?

0:14:08 Bryan: Yeah, part of it was confirmed in his lifetime. There are some other parts where he predicted that have been later confirmed.

0:14:19 Thomas: Yeah. Yeah. Like gravity waves and stuff.

0:14:24 Bryan: Yeah, gravity waves, that was very recent. Black holes, I don't think were detected his lifetime. That was, yeah, yeah.

0:14:28 Thomas: Yeah, so cool. Cool, did He Predict Black holes before Oh, really? Oh, okay. Oh,

0:14:35 Bryan: Again, it's more complicated than you think. It's another way of Black holes working, but there were older perceptions of black hole's saying, once you accept that light has a fixed velocity, and then there were a lot of other work on gravitational mechanics that say, okay, for any gravitational field, there's going to be a necessary velocity to escape from whatever mass is attracting, so it you have enough mass, you can always get to a point, uh, yeah,

0:14:39 Thomas: Okay, Oh, Okay, where Light itself can't escape, so You're saying that's the part that was unique to Einstein was, was that I was just gonna ask you, like, what's the part unique to him that, like, black holes would confirm, or something about black holes would confirm, that's Unique to his Theories Dogs

0:15:19 Bryan: And Part Of The, the Unique part to Einstein is that once things reach that point of a black hole, space itself basically breaks down inside the event horizon, uh, that, that basically space and time are flipped inside out, in short. Time becomes space, space becomes time. It's really trippy.

0:15:40 Thomas: And cats living together, Mass hysteria, I love this. Here's, here's something I've always wondered, and I know now I'm just peppering you with stuff that I, you aren't, you have not prepped, I don't think, and I, you know, no, no worries for any of that, but I've always wondered, so we've got this whole ether thing that turned out not to be true, of course, and we're like, no ether, that's not it, uh, be, but I always wondered, like, once you start talking about space bending in these ways and these different things, like, why isn't space itself the ether? Like, what are the differences between, between what space itself ended up being and what we, what people thought the ether might be.

0:15:40 Bryan: Yeah.

0:16:14 Bryan: I guess my best explanation is that it could have been. It's just not how the laws of physics are. And this goes really almost into philosophical territory of why are the laws OF physics the way they are?

0:16:22 Thomas: Ooh, I love it. Well, I just mean like, what are the, like, what's a thing that we would have thought would be true about the ether that isn't true about space itself, I guess.

0:16:34 Bryan: Okay. Okay, so I think, well, for Aether, it's basically that the of light will always be relative to the Aether. And if you move relative to The Aether that will affect the speed of light to you. But what we see in our universe is that whatever frame of reference you're in, the speed light will be the same. Like, imagine I Take out a super powerful gun, shoot a bullet that from my perspective is going 99% the speed of light, then a man is on the bullet, he has a flashlight, and he shines the flashlight ahead of him, from my perspective, the light from that is going at the speed of light, but from Ant-Man's perspective, who, to me, is going 99% of the speed of light, the light is also going at the speed of

0:16:40 Thomas: Mm -hmm. Right. Okay. Mm -hm. Mmh -hm, mmh -hmm,

0:17:16 Bryan: Light. And so that's the difference, a

0:17:17 Thomas: Mm. -hm. And That's not because, like, space itself is is bending or warping in any way? Okay.

0:17:24 Bryan: We aren't even getting to space bending. Space bending is part of general relativity. Relativity.

0:17:27 Thomas: That's Probably. Okay, that's Probably what I've confused. I thought, I think I've maybe confused those things, and I thought space kind of bending around was part of that, so okay. So that explains the difference, I got you.

0:17:37 Bryan: Yeah. So Special relativity deals mostly with velocity, position, time, and the speed of light. General relativity deals with acceleration and gravity, so

0:17:38 Thomas: Mm. -hmm. So special, just to review, even though it's kind of a counterintuitive, but special relativity is the super easy one that my babies can understand with a book. General is like, like the impossible one, is the very, no, I shouldn't say impossible, the very complicated one that, uh, Oh,

0:17:54 Bryan: It is ridiculously complicated and tough, and it's one of those things that I learned while studying for my PhD. I took a course that went into it, I did the maths, and then it immediately exited my mind.

0:18:11 Thomas: I bet.

0:18:11 Bryan: That's how bad it is. There are people who specialize in it and learn how to do it, but even most working astrophysicists understand the principles and don't worry about the details. They let someone else handle it.

0:18:11 Thomas: I bet this might be dumb questions, but why Why is it both called relativity? Why is one called special one general? Is it like a special? Well, yeah, I'll just let you answer it.

0:18:32 Bryan: Yeah, okay. So yeah, first question first. Why is it called relativity? It's because it deals with with relative motion. So originally, the easy way to shift reference frames that I talked about before is what's known as Galilean relativity. This is where you just subtract off everything. And then Einsteinian relativity, or special relativity, is where you apply some extra complicated modifications, which we call the Lorentz factors, off of Frangic -Lorentz and use the Lorentz transformation rather than the Galilean transformation to account for this. And because it's relative motion, we call it relativity. And then the difference between special and general is that general goes a step beyond. Instead of just looking at what happens when you have fixed different velocities, what happens When you're accelerating between those. So we've gone from this one subset where where things are relatively static, to when things are changing. So special is a special case of general relativity, which covers all of it.

0:19:08 Thomas: Right, okay.

0:19:38 Thomas: What's a so, I know this is so I'm not an academic, so It's hard to put things in the right terms, but like a thing you might learn in special relativity is what, this I just, are we talking equals MC squared, are we taking the okay.

0:19:41 Bryan: Yeah, part of it, you would learn about length contraction, time dilation, are things that come up, like when you're designing a particle accelerator, you need to deal with time dilatation, because particles will last longer than you expect when they're traveling at high enough velocity.

0:19:57 Thomas: Oh God, that's so cool. And the things like, for example, fact the the that GPS satellites have to account for, you know, time dilation and all that. Is that still special relativity or is that that is both? OK.

0:20:09 Bryan: Yeah, It's both, actually. So the satellites are traveling at a high speed relative to us, and they're also at a different point in Earth's gravitational field. And so the speed means there's a special relativity correction, and the fact that they're at a difference gravitational potential means there is a general relativity correction.

0:20:37 Thomas: OK. So the gravity type stuff is more the the general.

0:20:39 Bryan: Yeah, yes. So whenever you're dealing with acceleration or gravity, you have to go into general relativity. And if it's just differences in velocity, then you can get by with just special relativity.

0:20:41 Thomas: OK, OK. Okay. That's so fascinating. I love it. And general, is the case that they're, that's like still not all of it is confirmed or like,

0:20:58 Bryan: Relativity at this point, I would say, is almost 100% confirmed. I'm not sure if there are really any predictions from it. Think I gravitational waves were the last bit of it that had yet to be confirmed. And just a few years ago, we detected the first gravitational waves. So

0:21:13 Thomas: Right. Okay. So maybe I'm just thinking about the fact that like, the unified theory thing is the thing that people can't figure out, right? With

0:21:20 Bryan: Yeah. That's something. So unified theory is trying to figure out how this works alongside other forces. Is there some simpler explanation which explains all of them? And there's also questions about how to reconcile general relativity predictions with a lot of quantum mechanics. And So it's not that it's unconfirmed, it's just incomplete, and the incomplete parts have theories to do it that haven't been confirmed. But what for Einstein did, I'd say it's all been confirmed.

0:21:37 Thomas: Quantum, yeah, yeah. Right, that's so cool. It's just so so cool. I I know it's again, like you say, no, often science isn't a question of like one genius figures everything out, but like Einstein's pretty close to some of that, right?

0:21:50 Bryan: Yeah. Yeah. He's a yeah, he, he's very close to that with how far ahead he got of many others, yeah.

0:22:05 Thomas: Yeah. And, and and, is there anything significant? I guess the thing he got wrong is the, like, God doesn't play dice stuff, right? He kind of didn't, wasn't in love with the quantum stuff.

0:22:12 Bryan: Yeah. That's a, that's subject for another episode. We'll have to get into. Yeah.

0:22:16 Thomas: Oh, another time. Okay. Yeah. I just, sorry. I'd just get carried away with this stuff. I love it. Well, did we, did

0:22:17 Bryan: Yeah. Yeah. We still haven't explained how faster than light travel is time travel yet. Okay. Yeah, so let's get into that. So first, let's go back to, uh, definitions, get a baseline. So I think we've actually covered a bit of ground, so I think the first definition, uh, ask is, um, is the the present.

0:22:23 Thomas: Oh, yeah, okay. Let's do it. Oh, Yes, I love this because one of those questions that seems so effing obvious and then turns out, science-wise, there is no present. Like, it's just like, there's this part, it blows my mind. So you, you would, I'll try to be the step on the rake, as I always say, answer where I just give you the obvious answer, which is, well, that's just now, that's just right now.

0:22:48 Bryan: Yeah.

0:22:59 Bryan: Yeah that's just substituting a synonym, basically. It's like defining speed as how fast you're going.

0:22:59 Thomas: Yeah Yeah. Exactly Well, how else would I do it besides it being now?

0:23:11 Bryan: So the best way you can describe it, so let's say you haven't gotten into relativity. It turns out philosophers were actually struggling with this question as well. But the best way you can say it is that it is a point in time where that point refers to the time at which you're referencing it. So it's a self-referential point in Time you can think about. The problem with relativity is that it gets complicated when you try to refer to that point in TIME to other points in space. So if you have one observer and their path through the universe, you can refer to that observer's present. But me and you, I can talk about my present, but it's hard for me to talk about what the present for me is for you. Because you're over in California while we're recording this.

That's around 0 .01 light seconds away to a rough approximation. So my present for you. So the signals that come from you are going to be taking 10 milliseconds maybe to get to me in the best case scenario. Scenario. And so is you 10 milliseconds ago, or is it 10 milliseconds in the future when the signals from me get to you?

0:23:33 Thomas: Yeah as, so, so as a, you know, as a filthy commoner, I would just think that, you know, oh, there is some, it's hard to sync up exactly, but there's got to be some truth of the matter as, as to, like, in an absolute sense, if I slam my hand on this table, that happens at the same exact time as something you're doing. Even if we don't, you know, precisely know what that is. But there must be some fact of the matter there.

0:24:31 Bryan: Yeah.

0:24:52 Bryan: So the intuitive. Like for what I said, can you come up with intuitive answers. I said was it 10 milliseconds ago or 10 in the feature? Well, why not split the difference? That seems to make the the most sense? Or what if we have a third observer looking at us that said, okay, yeah, yeah, They see us both, and when they get, and the signals they see at the same time from both of us, for them are the present. But let's think this through a bit. Let's pretend we're not on Earth. We can see in any direction. So let's say we have one observer right in the middle of us, um, they look over at both of us, we both have a, we both wearing giant clocks on our shirts and facing them, they look at, at me, see the, the number zero, look at

0:24:52 Thomas: Yeah.

0:25:05 Thomas: And they're in neutral time. They can, they're objective about it.

0:25:36 Bryan: You see the number zero

0:25:36 Thomas: So we're Flava Flav, you're saying. We're all Flava Slaves. Okay. Okay. I

0:25:37 Bryan: Yeah, yeah, we both got clocks on our shirt, okay, yeah, okay, it's the same time for them, them, when the times on their shirts match up.

0:25:48 Thomas: I want someone to make a video or TikTok, a YouTube or whatever, that's like an explainer for this, but it's with Flava Flaves, like that's how you, you, because I think Einstein did the whole clock thing, right, you gotta, you gotta train and you got a big grandfather clock, whatever the hell, but like I do this, we need to update it and we need from 20 years ago or whatever, which is Flava Flav. Okay.

0:25:58 Bryan: Yeah.

0:26:09 Bryan: Yeah. So the observer in the middle says, okay, the them is when their say the same thing. But what if we had a different observer? What if the observer was sitting next to you and it takes a while for the light from me to get to them? So when they're looking at both of those, they say, okay well Thomas's shirt says one and Brian says zero. So it's the same time for both of them when Thomas Thomas is one ahead of Brian.

0:26:32 Thomas: Yeah.

0:26:32 Bryan: And so, you know, you've got two different observers disagreeing on this. They're given two different answers for what the present is. And once you factor in the finite speed of light and that it looks the same from any perspective, things start to get even weirder. And that when you change your velocity, not only do you get a absolute difference between the two, but the relative difference changes. So, for instance, you might have somebody moving at enough of a speed that says, okay, it's the same time for both of them when Brian's clock shows exactly twice what Thomas' clock says. So they'll see my clock moving twice as fast as you, because once you do all the maths to figure out how you have to keep the speed of light constant, the only way you can succeed at that is by squishing space and pulling apart time. Yeah.

0:26:36 Thomas: Right.

0:27:28 Thomas: And that's the golden rule, right? That kind of led to most of this is like, you have to Keep the speed of light constant. And it's just looking at, yeah.

0:27:32 Bryan: Yeah, because that was experimentally confirmed, and with that confirmed, other things that seem sensible, like time being a constant for everyone, or space being a constant, or you change reference frames by simple subtraction, you have to put question marks on all of those, and the only way it works is if you fiddle with all three of them.

0:27:42 Thomas: Yeah, just goes away. Yeah. I love it. It's so cool. This is one that it's harder for me to keep in my head with the whole time, current time thing. Um, I'm not, I don't think I'm falling as well, but let, so you're just saying, okay, right.

0:27:52 Bryan: Yeah. Yeah. I all you really have to follow is that there is no way to define the current time. You cannot present one universal definition of the present. It's always relative to some observer. Observer, yeah.

0:28:15 Thomas: So for me, I can say, Oh, I'm looking at my clock right now. It's a, you know, and I got it out to the, well, actually quick, quick second. And if this is a, uh、 not worth going down, feel free to, to veto me, but already before talking relativity, I've, I was wondering like, just philosophically, I wonder how you'd say like, well what is the the unit of, what is the base unit of time? Like what's the smallest amount of time that even makes any sense to say, just because it's hard to say like when it's now, what, you know, like, it's sort of like, if you're talking about distance, if You're saying I'm talking about right here, you're like, well, you can always zoom in and be like, are you talking about it right there? Are you talking, you're not like the more you zoom in, what precise point at my desk am I actually talking about? How does the same thing kind of apply to time where you're like, yeah, you zoom in and what, how, how far can you go there?

0:28:38 Bryan: Yeah. Yeah. So, from a physicist's perspective, the answer you'll get is what's called the Plank time.

0:29:03 Thomas: The plank length.

0:29:04 Bryan: Yeah. Which is, so there's the plank length and the plank time, which are closely related, you multiply by the speed of light or divide, depending which direction you're you're going, and that's basically the smallest unit of time you can make sense of, you know. There are smaller units of time, but you can't measure a different, smaller than that. It's basically the lowest wavelength of time you can have where you can say, okay, these two things are definitely at different time. And once it's less than that, you can say okay, there may be a different time, maybe at the same time, it's just too close to call.

0:29:04 Thomas: Yeah. Okay.

0:29:39 Thomas: So, so with that in mind, as a person here, I would say I have a very sensitive, uh, clock widget. I can be like, all right, well now is down to this plank time of me right here that I see that's now, but you're saying, okay, that's no, but that can only be now for me. There's no fact of the matter. To try to understand this, I can't be like, all right, we our clocks somehow. We start them at the same, you and I, we start at the same place and we sink Our clocks perfectly down to the plank time, we'll say.

0:29:57 Bryan: Yeah. So now

0:30:12 Thomas: So now, just and I know you've already kind of said it, but just to I think it's very complex stuff to understand. Now, let's say, all right. Well, let'S say we've all done that. Let'S say We've We've all gathered together here on Earth and we've synced our clocks to exactly the same plank, whatever. And then anything else, you're just like, well, we'll keep one of those clocks. We'll just keep that somewhere. And we'll just say that is now. That is the perfect now time. And that is. So why doesn't that work?

0:30:11 Bryan: Yeah, so you can. I think the problem is that once any one of you you start moving. The moving causes special relativity to kick in, and you're going to get a bit of time dilation. And so once moves away, all of their clocks are suddenly unsynchronized. Now, you can go back and you can resynchronize, but as soon as you try to do anything practical at different points in space, you have to take into account the paths you took to get there.

0:31:04 Thomas: So even at non -relativistic speeds, even just like I walk away, hypothetically, wow, right.

0:31:09 Bryan: It's going to have an effect. It will be small, but it will be a calculable effect.

0:31:13 Thomas: Right. But it's enough to where the Planck time, you know, like it's enough to wear that becomes different because you're at the smallest possible unit of time.

0:31:16 Bryan: Yeah. Yeah. Now, for practical purposes, this doesn't matter. You can get it down to the accuracy we need for humans, but, it is something that you need to be careful with.

0:31:29 Thomas: But we drive in a car, we go kind of fast that. So you're saying so anything we do is if we all stood still and did nothing, but anything we, and furthermore, anywhere else in space, like other, you know, other stars, other whatever's there, just isn't. You can't do some adjustment and be like, okay, well, yeah, they're a little bit ahead but like east coast time for me, but you know, they're all, they're still now. When you watch, when you record TV from another solar system, you're just like, okay, I'll watch the East Coast feed versus the West Coast feed, that just doesn't work, you're saying, because there's no, there can never be full agreement on what the wow

0:31:31 Bryan: Yeah. Yeah.

0:31:59 Bryan: So from a physics perspective, what ends up happening is the present is only meaningful at a single point. And so we just don't think in terms of there being a present. So, from a physics perspective, we end up splitting space into three categories. So, talk about this in curves, is the terminology, which is basically the path you would take from one point in spacetime to another. Where spacetime here is just your four -dimensional coordinates, x, y, z, and t. so, let's say our origin is zero. So, the first is time -like curves. Curves. This is basically any position you could physically get to.

So from 0, ,0 ,0 .0, a straight line to 0 ,001, where that 1 is in T, where all you do is go forward in time. That's a time -like curve. So that would be something at rest. Or 0 .1, 0 .0 .1 would also be a time like curve, since in the unit I'm assuming here, I'm less than the speed of light. So I'm going to just take a side note to talk about units.

Anybody who's gone through a science course in school probably remembers the teachers beating into their heads, always use units. The dirty secret is theoretical physicists go back on that promise.

0:32:15 Thomas: Oh They don't have to, oh man, I was born to be a three, I, I always hated the units. So frustrating.

0:33:28 Bryan: Yeah, you Get to the point where they use what they call natural units, which is we take a set of fundamental physical constants, which is to use the speed of light, which can give you a conversion between distance and time, and the Planck constant, which allows you to also have a conversion to mass. And then you just normalize everything by, though, you have one fixed distance. It could be like a light year.

It could be a light second, or it could be a fixed time or a fixed mass, and then everything is a multiple of that, whatever unit it is. So here I'm using natural units, and let's say our fixed unit is the second. So a one in the T dimension is one second, a one and the X dimension is 1 light second, so 0.1 in X is 0.10 light seconds. Talk about time-like curves, this is basically anywhere you can get to.

Like if we go out to T equals one, we can go anywhere in X, Y or Z, where if you calculate the diagonal out to there, it's less than one, so you Could go to 0.9 and X, you could go to point four and X, point four in Y, uh, four in XY, and Zed is even a bit less, but uh, can't go to point nine and X and point nine in Y, as that will be, you'd have to travel faster than the speed of light to get there.

0:34:35 Thomas: Hmm. Okay. Okay.

0:34:54 Bryan: Is basically a It's a -dimensional cone.

0:34:56 Thomas: I keep thinking in terms of three dimensions, but you're talking four dimensions, right? So it's a little hard to... I was imagining like a sphere almost where it's like those are the boundaries of where you could go, but I have to imagine like a four -dimensional sphere somehow.

0:34:57 Bryan: Yeah. Yeah, yeah, yeah. So why don't we even simplify things further? Let's say we have one space dimension, one time dimension. We've got x and t. So

0:35:12 Thomas: Oh, thank God. All right. Sorry, everybody. You're all going to get a lot thinner right now, but we're just one dimension. Or maybe That's good, I'm gonna go step on my scale and see, see if I've lost weight.

0:35:17 Bryan: Just don't slip through it. But you're not going to have much of a cross -sectional area to keep yourself on top.

0:35:22 Thomas: Yeah. All right. We're one dimension or two, two space dimension, we're What, two Okay.

0:35:27 Bryan: So one space dimension. It's

0:35:29 Thomas: One space Dimension.

0:35:30 Bryan: Simple. Everything works here. So our time -like curves, so it could be any amount of time out into the future, any positive t. It's also a time -life going backwards in time. So zero minus one is also time -lite. We've just got a different direction on it, but it is distinct. The past and future are distinct. Then it's also anywhere within, And so in one of space, you've got a triangle here. So if you're going up to one T, you can go almost all the way.

0:35:30 Thomas: Okay. Right.

0:35:57 Thomas: We So I'm A man Hold on, let's step back, this is a little hard because we don't have the visual. I'm in that, now that we have one space to mention and one time dimension, I'm, I'm imagining an X, Y plot of like normal two -dimensional graphy thing that you would have done in every math class ever. Is that what we're imagining?

0:36:00 Bryan: Yeah. Yeah. Yeah. Yes. Yeah.

0:36:12 Thomas: Okay. And you're saying the thing you're trying to explain to us right now is time -like curves? Is that What it is? Time -like Curves. Okay.

0:36:13 Bryan: Okay. Yes. Time -like curves. Yeah. So a time -like curve is any path you could take without going over or equal to the speed of light. So?

0:36:29 Thomas: Okay. So you're not saying time -light curve, are you?

0:36:32 Bryan: No.

0:36:32 Thomas: You're saying time? Yeah.

0:36:32 Bryan: Time. Like it's Like time, yeah.

0:36:35 Thomas: Okay. All right. And so you'd imagine if you've got one, okay, which one, X or Y, which ones time? Who cares? What do you want to do?

0:36:37 Bryan: Uh, It Doesn't matter. I always visualize it as time is vertical, so like the X-axis horizontal is still X. We just replace Y with time. That's how I visualize it, but it doesn't matter, so

0:36:47 Thomas: Okay. Gotcha. All right. And so your, you're talking, if we have one time, which is whatever it is, what I forget what you said, a light second or, okay.

0:36:58 Bryan: One Second. Yeah. Yeah.

0:37:01 Thomas: One second now. So I'm imagining that. And you said that's the vertical axis. So you've got like, kind of a, like, like that's a barrier there, and then you're saying the the timeline curve is what within one?

0:37:05 Bryan: Yeah. Yeah. The time -like curve is any point in space you could physically get to in that time. So it would be everything up, to, but not including minus one, up to, but not included positive one. So minus point nine, nine, no, no.

0:37:12 Thomas: Okay. Okay. Okay. So is it like a square or okay.

0:37:27 Bryan: Well. At this point, we just have a line segment going horizontally, but a time -light curve could be any amount of of time. So I've just chosen one, but we could also choose two.

0:37:33 Thomas: No, I know, we're we were, yeah, we're choosing one for now, just to try to understand it, is what I was hoping

0:37:40 Bryan: Yeah, yeah. So but we also choose two. And at two, we can go out further, we have more time to work with. So we could go almost all the way to minus two, almost all the way plus two. So then when we get up to three, we go minus three to plus three. So essentially, this forms a triangle.

0:37:42 Thomas: Sure okay.

0:37:57 Thomas: I'm trying that for some reason my brain isn't doing that. What's, what's the triangle? And I can, okay.

0:38:01 Bryan: It might help to think that if If we have two dimensions, it becomes a cone, because I know the cone was in your mind earlier. And a triangle is just a slice of a cone.

0:38:12 Thomas: So I'm just imagining this frigging graph paper. And what's the, what's the triangle if we've got, we've got zero, we got one, a negative one going up and down and

0:38:15 Bryan: Yeah. Okay. So let's an X through the paper where the Xs are at 45 degree angles, split exactly evenly between the vertical and horizontal axis. And then take the pencil and shade in everything in triangle, that is, between where it goes up left and up right. All of those points are going to be on time -like curves from the origin.

0:38:45 Thomas: So sorry. So why is it a triangle? Not like a diamond or a square thing is what I'm wondering. Cause if you got positive and negative.

0:38:52 Bryan: It's a triangle. Okay, so it's actually kind of an hourglass because you also have the triangle at the bottom as well. Think about this. You're planning a trip. You're going on holiday, and you want to get as far away from home as possible.

0:39:09 Thomas: Yeah. Okay. We can all that. Visualize Yeah, sure.

0:39:11 Bryan: You're a law -abiding citizen, so you follow the speed limit. You're not going to exceed 65 miles per hour on the interstate.

0:39:17 Thomas: Okay, let's make it a hundred miles an hour. Easier number. 10.

0:39:20 Bryan: Okay, okay, 100 miles per hours, and we're not even going to bother driving on the roads. We're going to drive across land. We're gonna drive across water. And so we think, okay, how far can I get away? Well, how long can I drive? How far I can get away.

0:39:22 Thomas: Yeah yeah. Anywhere we want. Okay it's a circle isn't

0:39:32 Bryan: Yeah, it depends on how far you're traveling. So if you travel one hour, you can get a hundred miles away.

0:39:32 Thomas: It? Like isn't 100 miles and so that that okay so okay that's where I'm confused because that's a circle right? Okay there's

0:39:42 Bryan: Yeah, yeah, yeah. So if You travel one you get a miles away, yeah yeah,

0:39:47 Thomas: A radius. We We know this in the fugitive. You're like let's search Church, every outhouse, hen house within, I picture, however, that's our situation. It's Harrison Ford. He's trying to get away. He can get anywhere within that radius because of the constraints of, you know, 100 miles an hour is as fast as he could possibly go. Okay. So that's a circle.

0:40:01 Bryan: Exactly. So now let's think, as time goes on, this circle gets bigger.

0:40:09 Thomas: Wider and wider. Yep.

0:40:10 Bryan: It gets wider and wider. So let's say, let's Say we're tracking a fugitive. We keep drawing these circles. An hour later, we draw a bigger circle. Then an hour later we draw another. Now let's, say, Okay, we want to think about where he could have been over time. So we take all the papers we drew and put one on top of each other. So on the bottom, we've, yeah, that's the cone. And yeah.

0:40:15 Thomas: Yep. Yep. Mm -hmm. Uh -huh. Oh, that'S the cone. Now you're talking. Okay. Okay. Okay. Thank you.

0:40:35 Bryan: And so the one-dimensional case is where we just basically take a knife, cut right through the middle of it, and look only at what's happening along that middle. And when we look at that, we're yes, exactly.

0:40:47 Thomas: Okay. And that's why it's a triangle. Oh, thank you. Okay. Thanks for bearing with me. Now I think I get it. All right.

0:40:52 Bryan: OK, yeah, we got it. Worries. I'm sure it helps the listeners as well. Well.

0:40:58 Thomas: I know it's one of those things where if you were giving a presentation and had a single PowerPoint slide, I would have been like, oh, okay. But since we're all listening, it's little harder to visualize. Okay, so we've got our time cone thingy.

0:41:10 Bryan: These are your time -like curves. This is basically the points in space -time you can physically get to. So the next classification is light -like curves. These are the positions that an array of light or something else traveling at the speed of light could get to, and these are just at the barrier. So our time -light curves are the ones, you the triangle and their light -like curves are the ones on the edges of it.

0:41:11 Thomas: Okay. Okay. Hmm. Mm. -hmm okay.

0:41:38 Thomas: Because inside the triangle is like maybe you were a little lazier and you're like, yeah, I'm not gonna go the full speed like you're

0:41:41 Bryan: It's lazier or it's the speed of light that got a bit sidetracked along the way, took a rest stop.

0:41:44 Thomas: Tired yeah yeah Yeah, but the outside is like, this is as fast as possible if you're always running super fast.

0:41:51 Bryan: Yeah. So light-light curves can get to the same destinations as time-light curves, but time-like curves can, this is everything outside the triangle. This is what we call space-like curves. And this is the closest thing we have to a present. This the set of all points, we call this a locus when we're being fancy, that you can't get to. And you can shine a light. It's basically that you You can't interact with these points at well, eventually you can get signals from some of them, as long as we don't start talking about the expanding universe.

0:41:51 Thomas: Okay, hmm. Okay. Okay. Hmm. Ever? That spans into the universe.

0:42:35 Bryan: Yeah, the expansion of the universe does mean there are some points we can never have any contact with. But yeah, yeah, you

0:42:35 Thomas: Yeah. Okay, gotcha. But for now, it's just within a fixed amount of time. These are points you can't have had contact with if they're outside of that thing. Okay.

0:42:47 Bryan: Can't get to those points. Within those points can't gets to you. There's no direct causal link, but you can eventually affect the same points. So that region of space, that locus, which we call space -like curves, are the closest thing we have to the present.

0:42:52 Thomas: Mm -hmm. Okay so why is that how is that the closest thing we have to the present?

0:43:10 Bryan: Because we've successfully undefined the present as anything else. So anything in the time -like curve is a potential future or potential past. Same with the light -like curves. You can assign a ray of light there. So the time-like curve that have a greater time are potential futures. You could get there. It could be your future. You might not, but you might be able to. And the light-like curves, you could send a ray of light in either the future or past direction. It will be either future or pass. The space-like curves are neither the future nor the past, so if we're shoehorning the present into something, it's all of those space-light curves. Yeah.

0:43:17 Thomas: Oh, okay. See.

0:43:57 Thomas: Okay. Think I get it, but that's very tough. But okay, we'll move on.

0:43:59 Bryan: Yeah. It's one of those things where we've undefined the presence and then redefined it as

0:44:04 Thomas: It's just everything that's not the things we defined, basically. Yeah.

0:44:04 Bryan: Yeah it so we're defining the present as not the future and not the past. Yeah. So now let's say we have faster than light travel travel and we do. Well, it gets complicated. The the problem with faster than light travel is that not going to be outright time travel. We're not going go directly into our past, but we are going faster than the speed of light, which means we're going into those space-like curves. Yeah.

0:44:11 Thomas: Okay, now the whole damn graph paper I just drew goes out the window, right? Yeah.

0:44:37 Thomas: We're we're escaping the barriers we thought we had on this graph paper, right,

0:44:42 Bryan: So we're into the space-light curves and once you start doing this, you can start applying relativity trick. So special relativity shifts the frame of reference of everything. And once you start moving, it basically tilts the graph paper. So let's imagine you have the just same piece of graph graph paper. You take a photocopy of it and put one on top. And this one on top is going to start moving. So when pieces of graph paper, one showing where you are at rest and one showing where you will be if you travel. So for the one that you travel on, your future is going to be along a path.

0:45:00 Thomas: Hmm.

0:45:22 Bryan: So if you stay at rest, your future is just here. And if you're moving, it's going to be along a tilted line. So in that one, your axis of time gets tilted. So you can think of this as, okay, when you start moving, you rotate the graph paper.

0:45:36 Bryan: Do you follow me? Yeah. Is more complicated than that. Order to make the maths work, you can't do it with a standard circular rotation, as we call it. You have to do what's called a hyperbolic rotation. And so instead of actually rotating it, you squeeze it in a bit, but it's not really relevant to the point.

0:45:36 Thomas: I think so well yeah we're gonna have to fudge it. This is already at the- I think this is at the extremes of what we can expect an average podcast listener to try to follow. Okay.

0:46:00 Bryan: Yeah, yeah. So let's just accept that when you change your axis for time, because you're rotating your perspective, you also change your access of space. And your access to space shows shows what seems to be at the same time to you in different positions in space. And if you get really close to the speed of light, that axis for space is going to be rotated to be really quick, to that light -like curve. So from one perspective, everything that's in the future to you is going to be the top half of the graph paper.

But from another perspective, it's going to be a tilted region of that, some of which goes into the past, quote unquote. Quote, not the true past, but space-like curves at lower time. So you can think, okay, what if we shift our velocity and then travel faster than the speed of light along one of those space-light curves that goes into kind of the past? Then we turn around, shift our velocity, go in the other direction. So we take two trips along space-liked curves going into the pseudo-past, and then suddenly we're in the true past. And this is basically how -than-light travel opens the door into it's the time travel.

0:46:12 Thomas: Okay hmm.

0:46:39 Thomas: Into are you saying this- stupid, but is are you saying because you go, I'm gonna go over there faster and light and then you're like, no, I'm gonna go back to where I was, are you- you're in the past now if you do that could be. Wow.

0:47:24 Bryan: Yeah, could be. You have to do some shifting of velocities in order to make it work. But But essentially, all faster -than -light travel is is traveling through space -like curves. And once you open the door to traveling through any space -light curve, you can go, you say, slightly down in time and over to the right on the x -axis. And then slightly down -in -time and over -to -the -left on the X -axis, both of those being space -life curves. But once you add them together, you've got a negative time -like curve.

0:48:01 Thomas: Part where it's the kind-like curves of different labels is where it loses me because my brain isn't good at keeping those- which one of those things are, but I trust that you're giving a very good explanation and maybe this is the kind of thing we somehow need visuals for, but okay if we're- if we're just putting it- in okay, people are like math and they can't- don't really, it's like the old- you're tipping at a restaurant and you just write math and then you write the number you want it to be at the end- the number we want it be atthe end is kind of what I said. Like, if you- if you are able to travel faster than the speed of light, you can go somewhere and come back, and And you could end up in the past if you wanted to.

0:48:05 Bryan: Okay, yeah. Yeah. Yeah, where the visuals really help and doing the best you can over audio.

0:48:26 Bryan: Yeah. Yes.

0:48:38 Thomas: You end up... How would you get to the future? Or is it only...

0:48:41 Bryan: Just wait. You don't even need to move.

0:48:43 Thomas: But can you move further in the future than you would be otherwise? Or no?

0:48:46 Bryan: Yes, but you don't need to travel faster than the speed of light. Special relativity alone allows you to go there. That's just time dilation. When you travel faster, you go into the future faster.

0:48:57 Thomas: Oh, because for you, stuff is staying still, but then everybody outside your spaceship got older kind of thing? Okay. Interesting. I guess I didn't think of that as time travel, because in my mind, time travel involves a flux capacitor and all that.

0:49:03 Bryan: Yeah. Yeah. Future time travel is perfectly possible at normal speed and above normal speed. If you want to go lower than normal speed, but still into the future, you have to accelerate the rest of the universe, but not yourself, which is a bit tricky to pull off. Yeah.

0:49:25 Thomas: Ah, that sounds hard. That's the Futurama

0:49:29 Bryan: Basically, Yeah, it moves the rest rest of the universe exactly

0:49:29 Thomas: Joke, the ship works by moving the rest of the universe around it. Oh, boy, well, okay, so have we covered the thing we wanted to cover, which is why faster than light travel essentially can equal time travel. Nice.

0:49:35 Bryan: Yeah. Yeah. Basically, we've gotten there, and this also bringing it back to the Picard maneuver, what this means is, so we've got the Stargazer takes a jump faster than light and you see it at two places in once, and so what's happened is it's traveled along a space-like curve. So theoretically, if the Enterprise decided that they, uh, wanted to break time, they could take a subspace transporter, which is a real thing in Star Trek that comes up in a later episode that works faster than the speed of light, go into the old Stargazer and transport Picard out before he could have engaged the Picard maneuver.

0:49:47 Thomas: Sure. Yeah.

0:50:24 Thomas: I, time travel does break everything, right? I know, I feel like this is one of those places. This is where the common man, the Thomas Smith, every man intuition is probably the same as the the physicist, which is once you introduce time travel, storytelling becomes incredibly difficult. I know, maybe that's something to talk about at some point, which istorytelling that works within with time travel with physics. That's an interesting thing.

0:50:27 Bryan: Yeah. Yeah, yeah, yeah. Trying to make time travel work physically is very difficult. Even trying to make it work logically is difficult. You'll hear a lot of physicists say, oh, this is very definitely how time travel has to work. And I'm not going to make any definite statements on that. There are different theories, but basically almost any form of time travel would break reality as we know it.

0:51:10 Thomas: Yeah, yeah. OK, well, that's a topic for another time, maybe. I maybe this will be something we could cover at some point but Ted Chang, he, uh, he writes short stories, one of which was made into the movie Arrival, I believe, uh, and, uh, he's probably my favorite sci-fi author. Oh, that, and the guy wrote the spider one that I can't remember with all the the spider planet it.

0:51:28 Thomas: That one was freaking cool. But, um, he wrote a story, one of his short stories. One thing he does is I think he does try to do this where, where I think He tries pretty hard to write sci -fi that, that, That works, you know, more or less given, given some stipulations. And he had one that was very interesting time travel wise. And I'd be curious, maybe I'll, maybe I'll try to get your take on it at some point, but, uh, yeah, that'll, that'd be something to, to look into down the line, but

0:51:28 Bryan: Yeah yeah okay that sounds good yeah that's only some of the best, uh, fi to read is where the author really does their homework and tries to make things work. Like, um, Martian is a good example of that. Both the book and the movie, where almost all of the science is as right as possible. Yeah.

0:52:02 Thomas: I love it. Okay. Hold on. Go into my complaints about that, but you know what? We've gone on long enough. We'll just cover the Martian at some point and I can yell about the thing. It's the same thing as always where like these characters should already know this, but they don't. Um, all

0:52:11 Bryan: Yeah yeah yeah they the human parts, obviously. There are issues. The scientific parts, it was in effort to be as right as possible. And yeah

0:52:21 Thomas: Right. Yeah, yeah, for sure. Love it. Well, Um. For today's purposes, what do you think? Are we a set? I mean, mean we got a solid uh two -parter here and

0:52:32 Bryan: Oh, yeah I think we've covered this from every angle and then some, and gone back in time and covered it before we started covering it. Yeah.

0:52:36 Thomas: Some fake ones yeah all right Well, if you didn't understand this, just go faster than the speed of light and keep repeating it until you do. Oh, wait, you could just restart the podcast here, you could actually just do that, but or, you know, either way, either one, whatever one is more convenient to you, but thanks, thanks as always, Dr. Brian Gillis.

0:52:55 Thomas: And And you're just a person who wants to helpfully explain stuff to us and is asked nothing in return and has no social media. So I don't know what to, what to follow

0:52:46 Bryan: Yep. Yeah. Oh, you're very welcome, Thomas. Well, about this, I won't plug my own stuff, but I've got colleagues who deserve a plug.

0:53:07 Thomas: Oh, there you go.

0:53:07 Bryan: So one of them who's going through a tough time right now with long COVID is Dr. Katherine Haymans. She was recently given the title of Astronomer Royal for Scotland, lind but then got covet and got long covet and has been able to do basically nothing with it but she still does tweets, uh, part of what she does is try to bring attention to the plight of people with long covet right now, so I'll plug her to give her some attention, her handle on Twitter is AstroRoyalScott. That's A-S-T-R-O-R-O-Y-A-L-S-C-O-T.

0:53:08 Thomas: Sure. Oh. Oh wow.

0:53:34 Thomas: Oh I love it. That's, great.

0:53:44 Thomas: What a great use of your plugging abilities here. I'll put that in the show notes. Great plug. And Brian, thanks As always, looking forward to next time.

0:53:49 Bryan: Okay. Yep. You're very welcome, Thomas. I look forward to it too.