SIO376: What Portal Teaches Us About the Physics of Our Universe

Transcript

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

0:00:15 Thomas: And Welcome to serious inquiries only. This episode 37 six. I'm Thomas and with me are several colds, but that's okay because when I recorded this interview, I didn't yet have this many colds. I got a friggin cough for like a month. I don't know what's going on. But then before I got over over that one, I got like a bonus one, another virus. I think I'm two, at least two viruses in right now. So that sucks.

Like I said, back when I recorded this, I was only one virus in, so you can't even tell. And today I've got once again, Dr. Brian Gillis, favorite astrophysicist. We're going to talk about the video game portal and what it teaches us about the physics of our universe. And I suppose possible other other universes. I interesting stuff about physics that I've actually never even heard of. Wanted to say too, we were considering maybe doing like a Q &A for Brian.

Like if I put up a thread on the Patreon, you people have questions for an astrophysicist? I know I would. That's why I do the show with Brian. But I thought that might be kind of cool. If not, we've got plenty of topics all the time. But yeah, the comments on this episode, let me know if you think that would be a good idea because we could totally do a, you ask an astrophysicist anything episode and that would be tons of fun for us.

So let me Know what you think on that. patreon.com/seriouspod if you'd like to get in on that and of course the ad free shows the monthly bonus. I can't wait to the next one of those Armageddon was so much fun. You really, really have to hear that whole thing if you haven't. All right, that said, let's get on over to Dr. Brian Gillis, and we're talking about Portal what we can learn about our universe from that little universe.

0:02:00 Thomas: I'm once again joined by Dr. Brian Gillis. How you doing today, Brian?

0:02:04 Bryan: Doing well, thank you. How are you doing, Thomas?

0:02:06 Thomas: Well, so did you see any cool space stuff lately. How's your space life as an astronomer over there?

0:02:12 Bryan: Oh, well, the Euclid telescope managed to launch without blowing up, which is a plus.

0:02:16 Thomas: Right but still a while until that thing's fully set up, right?

0:02:21 Bryan: It's in what's called the commissioning phase now, where they do a lot of steps that they, you know, just setting everything up. It's like, well before an audio recording, It's turning things on, hitting record, and a lot of other things. They've got to do calibration and that, and there are some minor risks there. I mean, orders of magnitude less likely to go wrong than something at launch.

0:02:45 Bryan: So, yeah, it's mostly not a worry. But, know, you one of the things we're a little bit worried about is that for the calibration of basically focusing it, One of the things we have to do is take it way out of focus, take some out -of -focus images to get some science data, which we can use to calculate how exactly the telescope's optics are set up through some really complicated math, and then put it back into focus. And there's a little bit of fear that it might get stuck out of Focus, but yeah, not. Yeah,

0:02:33 Thomas: Yeah Hmm Yeah I imagine there's a there's somebody's very anxious about the entire thing. I imagine there's a lot of people who will not be relaxed until it's all good, right? It's all like, all right, finally we know it works.

0:03:27 Bryan: Yeah, yeah. Definitely. Once data starts coming in, we can really relax. I mean, it's never a sure thing. I mean, you think of space as being empty, nothing can happen to it. But for one, this is something that was built by humans, there could be some subtle mistake in there somewhere. And another space isn't entirely empty. There's Actually, one of the threats that we have to deal with is what's called micrometeoroids, which are these really tiny chunks of rocks that we can't see up there, but could slam into the telescope and knock it about. You know, we could put it back, but they might knock the optics out of alignment. Worst case scenario, they could scratch them and screw things up. And you just have to hope for the best, really.

0:03:58 Thomas: Yeah, yeah, yeah. Well, we'll continue to hope and I can't wait until you can announce that that's all set up. But for now, today we're going to talk about Portal. I am very curious to what you have for us today.

0:04:24 Bryan: Yeah. Yes. So the reason I wanted to talk about Portal is that video games are actually very useful to help us understand physics when they can play around with it a bit. One of the things I realized is that if you want to understand how something is set up, one of the easiest way to do that is to look at specific components, take them away, and see what happens without them. And Portal does that with basically the fabric of space. It takes away some of our key assumptions about how space itself works. And from how things change, what aspects we lose, we learn a lot about how things are connected together in the first place.

0:05:12 Thomas: Well, for all the just, you know, there's a lot people who probably haven't played the game, weirdly enough, so we'd better explain the basics. I love Portal. I played. I actually haven't played as much Portal 2 as I should have, but I definitely played Portal 1. I mean, it's, it was so cool because I don't know if you know the actual, like, you history of like how it was made or anything. I don't, but I just remember, like, when it came out, I remember a lot of people thinking like this came out of nowhere. And it's the simplest concept, which is you have two portal guns. You You got one that's red and one that blue. And when you go in one, you know, one that makes a little portal, you go in, you come out the other. And just with that little bit of conceit there, just really cool game came out of it, you know, with these puzzles

0:05:19 Bryan: Oh, yeah, Yeah. Well,

0:05:55 Thomas: And things you got to solve and cool like momentum tricks, you so that's the game we're talking about. And I just remember it kind of coming out of nowhere, but I don't know if that's if that's accurate. Yeah, so you're going to tell me these portal guns aren't real, huh? We don't actually have those.

0:06:09 Bryan: Creating a portal is a bit difficult. Portals themselves, well, wormholes actually, that, that's one of the things I wanted to bring up, but, uh, the real universe, there, laws of physics don't actually forbid portals as such, just we call them wormholes. Uh, it is possible to that space, space could be set up in such a way to connect two distant points. It violate any law of physics that we can see. Opening a wormhole is something that we think is basically impossible to do, unfortunately.

But if one were to exist, it wouldn't violate a law of physics. Now, the fact that it doesn't violating a law physics doesn't mean it's true. Like, it doesn't violate a lot of physics for me to have a hippopotamus in my living room, room that doesn't mean it's likely to be true, though. So, um, would be very lucky to find any wormholes. Um, yeah, interesting to think about and do maps on what they might or might not allow.

And yeah, wormholes themselves, like, actually a call back to our episodes on special relativity, we talked about about how traveling faster than light is equivalent to time travel. And that's one of the things wormholes actually allow you to kind of sidestep the speed of light. And just thinking about it that way raises the question, would wormholes allow time travel? So

0:07:36 Thomas: So are we going to get into wormholes a little bit? Are you going to explain the basics at all? Or was that just a kind of quick stop along the way?

0:07:41 Bryan: Yeah. We can talk a little bit about wormholes, how things work in reality, and then go to the game and how things are different, and why that's relevant. So wormholes, wormholes in reality are purely theoretical. It's, you know, you get a bunch of physicists imagining, brainstorming about space and time and what could exist. And once you have the mathematical underpinnings of general relativity, and you start to think about space in time a bit differently, they came up with the idea, is it possible for space to be curved such that there's a hole in it that allows a shortcut between multiple different places? And the math in general relativity is ridiculously difficult. So I can't even begin to explain it here.

0:07:48 Thomas: Okay.

0:08:33 Thomas: But is it essentially like, okay, we always do the analogy of the earth. Is it just like going through, you know, if you were to tunnel through the earth and get to the other side rather than walking all the way there.

0:08:43 Bryan: That's a a good analogy to it. You can take shortcuts through space if it happens to be set up the right way. And people over time have done the maths on this and shown a few different ways, wormholes that could be set -up that were possible. The first is, they called it a plug hole, actually, because it only allowed one -way travel. You go in one side, out the other, which is what a lot of people imagine black holes like. You go into a black hole, you come out a quote-unquote white hole on the other side.

0:09:17 Bryan: And it is possible physically for a wormhole to be set up like this. Creating it, that's another issue, but one existing doesn't seem to violate any law of physics. Later, they were able to come out with models for wormholes traversable in two different directions. A lot of interesting ideas of what you could do with wormholes, and a lot people trying to figure out how to travel back in time with them, just because that would be like the holy grail of unraveling our understanding of physics.

0:09:17 Thomas: Oh, hey, look, I'd be satisfied to just travel someplace cool. You know, I don't need to go back in time.

0:09:53 Bryan: Yeah. I mean, just being able to get to somewhere else in the universe where there's something interesting would be night yeah yeah It takes years traveling at the speed of light to get anywhere, and that anywhere doesn't seem to have anyone interesting there. But if, like, well, like in Star Trek Deep Space Nine, you got a wormhole set up connecting you to another civilization across the galaxy, that would be amazing.

0:09:58 Thomas: No kidding. So disappointing. We're just stuck here.

0:10:19 Thomas: Yeah.

0:10:19 Bryan: Yeah.

0:10:20 Thomas: Now we're talking.

0:10:21 Bryan: Yeah, unfortunately you just have to luck into it. You, you know, with people doing this, we do believe there is one way wormholes could be created, but it unfortunately comes down entirely to luck. So what it is, is there's this thing called the quantum foam, which, have you ever heard that term before?

0:10:40 Thomas: Oh. I think I've heard that term and I thought it was just like like the ether that, you know, not literally, but just like that's what all of kind of reality might be.

0:10:51 Bryan: Of. Foam, you can more think, is like the zero point energy of empty space. It's

0:10:57 Thomas: I don't know what that is. What's zero point energy?

0:11:00 Bryan: Mechanics us in some ways that you can't have anything that is perfectly empty with no energy, and the zero -point energy is the absolute minimum of energy you could have anywhere.

0:11:12 Thomas: Oh, I see. It's like the resting, like just the default kind of energy of anything. Space, I guess.

0:11:20 Bryan: And what ends up happening is with this zero - point energy, which is non -zero in empty space, quantum mechanics takes a hold and random things happen because quantum mechanics is not deterministic, there's you probabilities know. And so every once in a while in empty space, you get weird things happening, like two particles will pop into existence out of nowhere, borrowing from the zero-point energy and then collide back into each other, annihilate each other, and return that energy, usually before anyone looks at them. In just the right circumstance, like if two of those particles are created right near the event horizon of a black hole, one might fall in and the other escapes, and they end up stealing the energy from the black hole. And this is one way that black holes can actually lose mass over time,

0:11:46 Thomas: Hmm. Ah, I remember this. Remember that. That's in Stephen Hawking's book. Is that Hawking Radiation? I remember reading that and just thinking like, really?

0:12:20 Bryan: Is yes, that's it, Hawking radiation, yeah.

0:12:27 Thomas: Like it just seems So, I mean, for one, how often is that happening? Like, is that just a massively slow process that, you know, would take all of the entire length of the universe or does that happen more often than I would think?

0:12:39 Bryan: Even more slow. It does happen, like, number of events is significant, but black holes are so ridiculously massive that it would take many times the current age of the universe for black holes to evaporate. They eventually would, but we're talking eventually in astrophysical terms. So it's, it's not something you're just going to sit there and watch a black hole evaporate.

0:12:40 Thomas: Oh, okay. Yeah. Yeah. All right. Well, I won't, Won't Mark yeah, My Calendar or anything, but why, we know that for a hundred percent certain? Like what, wow.

0:13:05 Bryan: Yeah. Quantum foam has been experimentally proven, um, they went through, um, tested, um, some of the predictions of it, and, um, basically it comes down to you can measure the difference in zero point energy of empty space just out in the broad universe versus empty space in a contained area. And quantum mechanics and the understanding of quantum foam predicts that the empty space in a small contained area will have a lower overall energy than empty space in the wide open universe. And this will cause a measurable pressure on, if you have two metal plates very close together.

0:13:51 Thomas: Oh, yeah.

0:13:51 Bryan: There'll be a pressure pushing them together, which is called the Casimir effect, and this has been tested and shown to be true.

0:13:51 Thomas: The metal plates. Oh. Wow.

0:14:00 Bryan: So quantum foam is experimentally tested, as weird as it is. Where it gets into wormholes, it's believed that quantum foam could give rise to wormholes, just pair -producing small wormholes with ends being separated by a bit. And then like most things created from quantum foam, most of the time they'll just collapse right back into each other and disappear. But the trick is, very early on in our universe's lifetime, it expanded ridiculously rapidly, a period we call inflation that happened right after the Big Bang. I mean, by our timescales, almost instantly after it. And so the idea is if right before or maybe during inflation, a wormhole was created out of the quantum foam and then space itself stretched out to a ridiculous extent, the two ends of the wormhole get very separated in space and it gets stuck open. It can't fall together. And so we're left with the wormhole just randomly existing.

0:14:00 Thomas: Yeah. Oh.

0:15:12 Thomas: That would be so cool, but how would it be stable, like,

0:15:15 Bryan: Are questions that get into quantum gravity, which I'm unfortunately not qualified to explain. Yeah, yeah. Quantum gravity is in some sense, the final frontier of theoretical physics, trying to combine general Relativity and quantum mechanics. And it is very tough. But that actually kind of gets into one of the things I was going to lead us into with talking about Portal, is wanted to talk about, is basically getting down to the most fundamental laws of the universe. Use an analogy a while back when Twitter had just been bought up by Elon Musk, and he had the brilliant idea to fire all the programmers who have written the fewest lines of code. There was a meme I saw. It was one those formats where you see the IQ bell curve distribution and

0:15:21 Thomas: A quantum gravity, oh, when will it end? Yeah. Right, yeah.

0:16:07 Bryan: At one end you have the low IQ, mid IQ, high IQ people. And on the low end, you see a programmer, okay, writes code plus 10 lines. Middle writes code plus 200 lines. And the high IQ programmer writes code minus two lines. The idea is the really smart programmers are able to cut out the cruft in code.

0:16:22 Thomas: Yeah. The old, if I had, uh, more time I would have written you a shorter letter, or whatever the hell that is, yeah.

0:16:33 Bryan: Of the things that kind of goes on with physics, that it's great if you can discover a new law of nature, but it's even better if you can discover negative one laws of nature.

0:16:33 Thomas: Oh.

0:16:43 Thomas: You can get rid of the law of nature.

0:16:45 Bryan: Yeah, or show that two laws of nature that you used to think were independent actually come from the same source. And this is what Albert Einstein spent like the latter half of his life doing. He came up with general relativity, which covered a lot of gravity, and his holy grail was a theory of everything. He wanted a theory that not only explained gravity, but all the other forces of the universe, as electricity, magnetism, the strong and weak nuclear forces. He wanted to take those four different forces and compress them down into one. He wasn't able to do that. And we're still working on it today.

I wanted to give an overview using Portal to help explain things of one of the big strides we've made into cutting down the number of fundamental laws of physics we have. And that's a tool called Nutter's theorem, developed by the theoretical physicist and mathematician Emmy Nutter, who is one, say, my favorite physicist, for just what this theorem does for us. So basically, this theorem connects not just a couple different laws, but a large number.

Boiling it down, what theory says is that for any symmetry of space, I'll come back to that, what that means in a second, and there is an associated conservation law. So what this means is that every conservation law we have, in some way, it gets a bit more complicated with quantum mechanics. We don't need to go there. Every conservation law we have comes back from some symmetry of

0:16:45 Thomas: Cool. Cool. Yeah. Yeah, yeah.

0:18:31 Bryan: Space. Space.

0:18:31 Thomas: And do you mean like conservation of momentum, energy, those those ones? How many of those things we got?

0:18:35 Bryan: Exactly. The ones that come out of Nutter's theorem are momentum, energy, angular momentum. This is like how things are spinning. And the one, oh, in some extent, the fourth one, which is really patterning the called the center of mass theorem. It doesn't even get to be called a conservation law, and it falls out very nicely of just regular conservation of momentum. Basically, center of mass theorem says for an isolated system, the center of math will move at a constant velocity. Conservation of momentum, you can see, is already pretty close to that, that within an isolated systems, the total momentum. Momentum, so that one, yeah, if you look for the lists, center of mass theorem shows up, but it is kind of padding the

0:18:48 Thomas: Are you padding the resume with that? That's just momentum still.

0:19:17 Thomas: Yeah.

0:19:26 Bryan: Resume. Yeah, when I learned about this, I found this amazingly cool as it's uh, connective tissue behind uh, lot of laws and

0:19:36 Thomas: So How does that, so you're saying I think I totally understood so, so for each of those conservation thingies that some, some more real than other, they're is it they're created by or they're caused by?

0:19:37 Bryan: Yeah. Yes. Each of these is a... So conservations, what it says is these aren't fundamental laws of the universe, but each is a consequence of other properties of the universe. And in particular, they're consequences of symmetries of space. So I think now we need to define this. So first of all, when I say symmetry, what does that mean to you?

0:20:09 Thomas: I don't know. Just the same on both sides.

0:20:11 Bryan: Okay, yeah, that is one type of symmetry. And in physics and math, we use it for an expanded definition. It's not just the same on both sides, but it's the same when you do something to it. So an example example would be like imagine you have a perfectly smooth round ball with no defects in it. You might say that this is spherically symmetric as whatever angle you orient it at, it'll look exactly the same.

0:20:38 Thomas: All right. Right. OK.

0:20:46 Bryan: Now, it also has the reflective symmetry, as you mentioned, that if you reflect it like in a mirror, it'll be the same. Could also have things like an infinitely long line with no defects. In this case, we call that translational symmetry, that you can move anywhere along the line and it's still infinitely long in either direction. In the most general sense, a symmetry means that things are unchanged over some transformation of coordinates. That is, We move our perspective in some way, and things are still the same. So it might be we move position, we flip our perspective around in a mirror, we turn, or as we discussed in the relativity episodes, things are the same if we move to a different velocity. Velocity, so all of those are symmetries, and Nutter's theorem tells us that every one of those symmetories will give us a conservation law.

0:21:07 Thomas: Huh.

0:21:44 Thomas: How?

0:21:45 Bryan: And that's where portal comes in. The how, what Nutter'S theorem said, it came of calculus of variation, so if you want, we can go into the calculus proof for it, but I think portal might be a bit more easy for people to understand.

0:22:02 Thomas: We can do that on our own time. Still.

0:22:03 Bryan: Yeah. Okay, so let's go into portal, and this really helps us. And first, I think we should actually just list the key ones, momentum and energy. I think those are the most important ones we'll get out of this. So momentum specifically comes from the symmetry of space. That is, the fact that space is the same everywhere gives us conservation of momentum. And energy comes from symmetry of time. That is the fact that things don't change over time. The laws of physics now are the same as the laws ofysics two minutes from now. And it gives us preservation of energy.

0:22:45 Thomas: Don't know how, but okay. Ah.

0:22:47 Bryan: Okay, yeah, I'm just saying where things connect up, and once we get into portals, we can see why. So. So. The game Portal, a lot of the fun of it comes with you introduce portals, which are basically like wormholes, except, you know, real world wormholes would be spherical. These portals are flat surfaces, so one flat surface on one wall connects to another. So for instance, you could put one down at the ground floor of a building, the other at the top floor, walk in the portal at the ground floor, and all of a sudden you come out at the top floor of the building. So.

0:22:55 Thomas: Okay. Yeah. Yeah.

0:23:27 Bryan: That's basically how portals work in the game. And this allows for a lot of interesting puzzle solving. The game starts you off simply with using them to help navigate around, and then once you've got the hang of things, it starts introducing twists on it. And the first twist is that speed is conserved going through a portal. Now, actually, the first game incorrectly says momentum, which isn't true because momentum is directional. So imagine this way. You've got on the north wall of the room you're in, you've got two portals, one beside each other. You go into one heading north, you'll come out of the other heading south.

0:24:11 Thomas: Oh.

0:24:11 Bryan: So the momentum you have going in has both the speed and the direction. So speed, yeah, yeah.

0:24:17 Thomas: It's why it's A vector, it's one of those vectory ones. That has to, okay, yeah, gotcha, so it's reversed. Essentially. In that case, right.

0:24:22 Bryan: Or you could have a portal on the west wall, you come out going east, it gets turned.

0:24:28 Thomas: 90. Degrees. Yeah, right.

0:24:30 Bryan: Or it could be on the south wall, Maybe you go in and the momentum doesn't change. It doesn't have to change Going through a portal, but it certainly can. Fact that it does change allows them to do a lot of interesting things with it. One, the simplest, is you put a portal face down on the ground, then you jump off into to the portal, then all the speed you get up, uh, going down through gravity will be translated into horizontal motion. So you set up another portal over on the wall, jump down into one, come out out the other, and you can shoot yourself a claw across a big gap and So yeah, lots, lots

0:24:37 Thomas: Right. Right. Right. Yeah. And

0:25:11 Bryan: Of puzzles Like This

0:25:11 Thomas: Even lets you like put you put one on the ceiling, put on the floor and then gravity just kind of keeps accelerating you for until I guess you reach the terminal velocity or something.

0:25:12 Bryan: Yeah Yeah One Of those things Yeah Yeah At some point you're going so fast air, air resistance balances out against gravity, and you just create like a heat engine, heating up all the air around you. When you look at it this way, so momentum isn't conserved with portals. It also turns out energy isn't conserved because, yeah, you can do this thing, put one on the floor, one on this ceiling, keep going down, keep doing faster and faster, faster and eventually, yeah, um, well, just imagine the um case you came up with. You put one portal on the ground, one on the ceiling above it. Jump into the one on the ground, you'll come out on the ceiling, then you'll fall down to the ground again, uh, picking up speed as you fall further,

0:25:29 Thomas: Yeah. Yeah, yeah. Oh, wait, that means energy isn't conserved. I thought it it was. Yeah yeah. Right,

0:26:05 Bryan: Go through it, come out the top again, fall again, pick up more speed.

0:26:06 Thomas: But I thought the very thing that it is doing is conserving the energy because you're the gravity is still gravity is still gravity, right? So the gravity is just increasing your speed, but

0:26:10 Bryan: Uh Well, it's conserving the kinetic energy energy. What it isn't conserving is the potential energy. Energy unlike momentum. Momentum can only ever be one thing. It's the motion of mass. Energy can be many different things. So there's kinetic energy, which is from the motion -of -mass, though unlike momentum, energy has a scalar, and it depends on the square of velocity. It can be complicated complicated structures of the motion of mass, like sound waves, can be energy. Energy can be turned into matter, or matter can be turned into energy through nuclear reactions and similar. Energy can Be turned into rays of light, photons store energy, or energy can be held in potential energy. And potential energy is, in a sense, a fiction that physicists come up with to keep energy conserved. So you can think of it this way. Imagine our universe is a flat earth with constant gravity downwards.

0:26:25 Thomas: Okay, right. Yeah okay ah

0:27:24 Bryan: If all the energy you care about is the kinetic energy of things moving, that energy on its own isn't conserved because let's say you take a ball, you toss it up into the air. It'll start out with some velocity, it'll rise up a ways, and then eventually it'll slow down, do the gravity, and come to a stop. And at the point it stopped, it has no kinetic energy. We introduce potential energy to kind of fill in the gaps of where the energy is gone.

And potential just kind of means what it intuitively does. It's the energy that could be added to particles if all the forces that exist on the universe were able to act on them to the maximum extent possible. So potential is like how much energy could this have if it were to go down as far as possible from gravity? Back to our portal example, you've got one portal on the ground, one on the ceiling.

When you go through the one on the ground your speed stays the same, so your kinetic energy stays the sam, but you've gotten up a lot higher, which means you've gotten a lot more potential energy.

0:28:35 Thomas: I see, gotcha.

0:28:37 Bryan: So by the time you fall back down to the ground, you've picked up even more kinetic energy. And this just keeps going into a loop, all the time gaining kinetic energy, and every time you go through a portal, gaining potential energy?

0:28:49 Thomas: So So you're essentially just cheating into free potential energy, and that's why you said we're not conserving energy because we're sort of just adding Okay, gotcha, that makes sense, hmm.

0:28:58 Bryan: Yeah. Yeah, yeah. This is where Nutter's theorem comes in to explain things to us. And let's start with momentum, as that's a bit simpler to explain. If you go at it from a mathematical perspective, Nutter's theorem tells us that translational symmetry of space is what gives us conservation of momentum, means that if you don't have have symmetry of space, you don't necessarily have conservation of momentum. It's one of these one-way theorems that you can have a conservation law without the symmetry, but if you do have the symmetry you must have the conservation law. And essentially you can think of it kind of intuitively. If space is the same everywhere then you're not going to automatically lose any energy or anything by moving to a different spot in space, unless there's something else acting on you. And if there's nothing else acting you, Newton's third law comes into play, which says for every force, there's an equal and opposite force in the other direction. So it kind of works like that, that you don't just spontaneously lose momentum. If you're going to to lose momentum, you have to give it to something else.

0:30:04 Thomas: Yeah like wind resistance or something, something something will be acting the other way, gotcha.

0:30:29 Bryan: Yeah. Yeah, and like gravity, we talked about this in a previous episode that, you know, we had the neutron star and the big ball of junk that it's sucking in, and they both orbit each other because the neutron start has gravity, attracts the ball of chunk. The ball of junk's has gravity attracts the neutron stars, so they trade off momentum between the two of them, but the total momentum is always conserved.

So, if you wanted to violate conservation of momentum, you would have to lose it, but not give it to anything else. And the only opening for this is if space itself breaks down. And it turns out space itself breaking down is exactly what portals do.

That, yeah, is, if you open a portal on one wall and have it change into a portal facing a different direction, you've got a big breakdown in the fabric of space itself, and so you can think about that, as soon as you go through that portal there's, you know, one discrete instant where you get transported to different place, or different parts of your body will be transported at different times. But But there's one specific place where space breaks down.

And it's as you're traveling through that, that conservation momentum is no longer guaranteed. Now, as we've gone before, you might still have it. Like if you have one portal

0:30:32 Thomas: Right

0:31:58 Bryan: On the north wall, one on the south, you still go north.

0:31:58 Thomas: And they're at the exact same, like, elevation, so you're not adding any gravity potential energy kind of thing, yeah.

0:32:04 Bryan: Yeah. So you might still conserve momentum, but you don't have to. There are a lot of ways. So it opens a door. And Nutter's theorem is what tells us that our intuitions, like what the game is doing here, is right. If break down space, yes, you do lose conservation of momentum, momentum, and so this is just kind of giving us insight into the scaffolding that holds up our core laws of that physics, conservation of momentum is one of these consequences, and you, if you play through the game of Portal, you can explore all of the consequences, and it's interesting to play around with it and think, could the universe actually exist this way, does, does the lack of conservation of momentum or conservation of energy, actually, yeah, yeah. It can make things very convenient.

0:32:53 Thomas: I it's self-traffic, am I right, well, I bet there'd be a lot of wormhole traffic, like, eventually be like, I shot a portal and someone else comes out of it, damn it, just, ah, man, rush hour, so,

0:33:10 Bryan: Oh, yeah yeah that would be the risk. Imagine if the wormholes themselves can collide and, or you shoot one, shoot but the tubes crossed and you come out in Bangladesh when you're trying to get to New York.

0:33:23 Thomas: Yeah, is that actually possible? I'm now, I'm trying to think, like, the real wormhole, if it existed, like, is there something that could get tangled, or is it literally just, like, you've poked a piece of paper, you fold a piece paper in half, poked the pencil through it, you can't really, I guess there's no, there's no, like, ether you go through, there's not, like, you know, it's just, you're, you're just physically out on the other side, no matter what, right?

0:33:44 Bryan: Yeah. Something that's a bit beyond me, unfortunately. I haven't gone into all the general relativity and quantum gravity behind that.

0:33:49 Thomas: Oh, okay. Yeah. Maybe when portal three comes out. Okay.

0:33:56 Bryan: Yeah, yeah, I don't know if Portal 3 is coming out. Although I do have good news for you. There is a fan sequel called Portal Reloaded that basically adds a time travel portal to the game. I've been playing through that recently, recently it's up on my YouTube channel. So if you want to get an idea of it, you can check it out there. And it is quite fun, although very hard, as they start out assuming that you've already beaten Portal 1 and 2 and you're ready for expert level puzzles with an extra portal.

0:34:25 Thomas: Nice. I love that.

0:34:27 Bryan: Back to the game, what's fun is seeing that, you know, reality gets gets more interesting with portals. But the conservation of momentum, it turns out wasn't it one of the core pillars of our reality. We can get rid of it and it allows weird and interesting things to happen, but reality itself doesn't break down. And it turns out the same is true of energy as well. Things will be different if you lose energy, but but things don't break down. And it's at this point that I actually have a dirty little secret for you, Thomas.

0:35:02 Thomas: A portal.

0:35:02 Bryan: Don't actually have conservation of energy in our universe. It's one of those things we say we do. And well, we...

0:35:03 Thomas: Oh, It's just a conspiracy made up by physicists. You'RE SPILLING THE BEANS. We found the one physicist willing to tell the truth. They're going to come for you. We might, we gotta be, have we anonymized you? Cause you know, know, the physics cabal. They're going to assassinate you.

0:35:16 Bryan: Yeah. Yeah. Oh. Are some who argue that, okay, well, it's just potential energy, it's going into potential, but as I said, potential energy is kind of a cheat, so let me explain what's actually going on. The reason we don't have conservation of energy in the real universe, you can explain from Nutter's theorem, is that we don't actually have time symmetry in the universe. And the reason we don't have time cemetery is the universe is expanding.

0:35:36 Thomas: Yeah.

0:35:56 Thomas: That's why we don't have time symmetry? Okay.

0:35:58 Bryan: Yeah. I mentioned before, it isn't just that things are getting farther apart from other things. It's space itself expanding. Is And something that you only see over extremely large scales, but it does have an effect. This is what causes light to be redshifted over significant amounts of time. So one way to think about this is from the perspective that if we think about it as like us stationary, everything else is going away from us, redshift makes some amount of sense as like a Doppler effect on light.

0:36:17 Thomas: Right.

0:36:33 Bryan: It's going away so the peaks between the waves get farther and farther apart. And then you can change your frame of reference, look at it from something else, see the same thing there. But things get a bit complicated if you look at the entire universe at once. If you look like all the photons going through the universe at once, track them going in every direction, you'll see all the photons steadily getting redshifted.

0:36:33 Thomas: All redshifting. Yeah, it's not like there's some blue shift somewhere compensating. And so are you saying that's essentially we're losing energy there and it's going anywhere?

0:37:01 Bryan: Yeah. Yeah, the redder light is, the lower the energy is. And it's this expansion of the universe that very slowly takes away energy from everything moving, most notably with the redshifting shifting of light. And so on a cosmological scale, energy is slowly being sapped away from the universe.

0:37:21 Thomas: Yeah.

0:37:30 Thomas: Someone's stealing our energy. We got to find Out who it is. Yeah.

0:37:32 Bryan: Yeah. I the Christians have an idea about that. I'm not too keen on their solution, though.

0:37:36 Thomas: Yeah. Is there some way that potential energy solves that with this particular thing? Like, do you say like, oh, no, it's just the, the photons have now traveled more to, I don't know.

0:37:49 Bryan: Could, but it kind of exposes potential as even more of a cheat as you're saying potential, okay, the potential is slowly increasing over time. We're losing energy from the photons, but that's because it's going into a higher potential energy as the universe expands, which It, me, honestly, I see that as a bit more of of a cheat. Potential energy in normal circumstances is kind of fictional, but it's a very useful fiction. It works a charm for calculations. But when you get into the of the universe and just having a flat potential across the universe, which changes over time to explain the loss of energy, in fact, the potential increases over time as the universe expands, you can maybe argue that, but again, we're really just splitting hairs.

0:38:08 Thomas: Yeah.

0:38:44 Thomas: That Just that's Just Creative accounting, that's just saying, no, we have the same amount of money. It's because this fund over here, it just happens to go, I donno, up the same amount that our bank account is going down. But it's nothing, it's just you writing a number that's the opposite of the number to compensate? Is it like that kind of?

0:38:44 Bryan: On The Yeah. Yeah. Yeah. Basically.

0:39:01 Thomas: Whereas with potential energy and like basic calculations, it makes it, you know, what's funny is the minute you said potential energy earlier, it's something that I just haven't thought about, you knows, since like high school physics or something. No, I probably thought about since then. Oh, I had college physics now that I think about it. But the minute I, you said that, I was like, oh, that is kind of a weird concept. It's like you take the same, I don't know, like a banana or something.

And I'm holding it right here. It's got one amount of some sort of potential energy. And then I move it up and then like it's sitting somewhere and I've, to it's like, potential energy, because theoretically now it could fall from there and have more energy than it did. Right. Is that what it is? But there's nothing in the banana atoms where you'd be able to look at it and be like, Like that's got more energy. It's not, there's nothing, it's not energized more. So it is kind of curious, but it does make sense. Cause it's like for every force, there is an equal and opposite, for all that stuff. It's just like the time delay kind of, right? Like, it does happen. It's juste, it hasn't happened yet. So it's kind of the, the accounting there is more like a real kind of accounting where, oh, we actually do have a different bank account, and it is a real amount that we've moved the money into, and someday we'll move it back, and that's all fine.

0:39:40 Bryan: Yeah. That's Right, yeah. Yeah.

0:40:11 Thomas: Does that make sense?

0:40:11 Bryan: And Yeah. It is, and potential, I think is a very well named concept because it's energy you could potentially get out of. It, you could like take a banana up, and then you have the potential to drop it, get the energy back as kinetic energy, but it's only potential. You could eject the banana into space, give it a ton of potential, but it might never come back. So it's a maybe thing. And the reason I don't like using potential for the expansion of the universe is we can't get that energy back.

0:40:19 Thomas: Yeah. Yeah.

0:40:45 Bryan: It's going into some bank account that we never have access to.

0:40:49 Thomas: I was curious if you were going to paint some like image of a way that that makes sense. Like that's some, but it sounds like there is no, you know, is there some quantum -y way that this energy is potentially there for someone to use? But it sounds like, no, there is a way to make it possible. There is no way for anyone to kind of like use that energy that would have been hypothetically stored up, right?

0:41:10 Bryan: Maybe. I'm trying to think, but

0:41:13 Thomas: It need to be like external to the universe? Would Would it need to be like, okay, if you could imagine our universe as like a, you know, some sort of orb somewhere floating in a cosmic foam, it's expanding and it's actually that in itself has more energy now or something. I don't know.

0:41:28 Bryan: Yeah. That's possible. If there's something outside our universe that it exists within and can act on it, maybe there's some way this can can happen. But, you know, as I said before, Noether's theorem tells us, if we don't have time symmetry, we don'T need to have conservation of energy. So we might just be so committed to the idea of conservation of energy that we're trying to shoehorn it in when we don' t need to.

0:41:47 Thomas: Ah, yeah. Ooh, you Know What? Nother is the Fed. Nother was like, yeah, we can print money, man. It doesn't matter. We can print monies. Fine. This is a fiat currency. See, we don't why are you so attached to the gold standard over there with your conservation? Among oh, this is a great analogy, actually. I think this is working. This is helping me.

0:42:12 Bryan: Okay, that's the big conspiracy about conservation of energy. But now I want want to bring you back to Portal, because there was one subtle point which occurred to me while I was thinking about this and prepping for the episode, and got me going down a bit of a rabbit hole of figuring out the physics. And that point is, Noether's theorem tells us we get conservation of energy from time symmetry. And in Portal, we can break conservation of energy if we have, for instance, like one portal on the ground and one on the ceiling. But a setup like that, where the portals just exist there, doesn't actually break time symmetry. We've just got a static setup. And

0:42:52 Thomas: Because the portal universe isn't expanding we're just in a just a normal whatever's the- yeah, what's the opposite of that? Just a stable, you know, no, okay. Gotcha.

0:42:56 Bryan: Yeah, yeah. Steady state.

0:43:05 Thomas: Yeah. State- State-to-state Portal universe.

0:43:05 Bryan: Well, no, steady state is a different model, But we could just say it's static static. That's the word Yeah, So we've got a non-expanding universe, one portal on the floor, one at the ceiling. You could toss something through the one on the, it comes out the one, the ceiling. And there's no breaking of time symmetry. Because the laws of physics, the set up doesn't change. So why don't we have conservation of energy? And I actually went through a lot of thinking and research to figure out, and and it turns out that I was actually missing it at the beginning of Noether's theorem. And there is that Nutter theorem doesn't exist in the vacuum. It has one underlying assumption.

0:43:08 Thomas: Oh, yeah. Yeah. Okay. Hmm.

0:43:39 Thomas: Interesting.

0:43:50 Thomas: Ah.

0:43:50 Bryan: Well, technically more than one. One of the assumptions is that math works. Math makes sense. You do have to assume you...

0:43:58 Thomas: This sounds like my... Like, this... Honestly, can I be honest? This sounds, like, you really fudging an explanation for why you couldn't figure out your homework. Oh, no. Here's the thing. I was missing. Math has to work for this to make sense. And you're like, oh, okay. So, the problem is math, Brian. The problem is not you. It's math. Half.

0:44:14 Bryan: Well, that's one of them. No, no, no. It's not. Math still works. Portals don't break math. So that wasn't it. It's the other underlying assumption. And underlying is that, well, there are a few different ways to define it, but the way Wikipedia lays it out is that all forces are conservative. That is, so what a conservative force means is that basically amount of energy transmitted by a force or lost to a force is independent of the path you take between any two places. So let me just explain this so let's

0:44:21 Thomas: Oh, okay. Okay. Huh. All

0:44:53 Bryan: Get our banana up in the air Let's say I put a banana on roof of my house and I want to take the banana down, put it in in front of my front door. So we've got two places now. There are an infinite number of paths I could take between these two places, and you've got the forces of gravity pulling it down. And you've got a lot of other forces acting on it, but let's let's just think about gravity right now. So one option is it just falls down to the ground and then I push it over to the side. So it gains energy from gravity going directly to the.

Another option is it goes blasting off into space nearly at escape velocity, but eventually comes back and hits the ground And, you you can list off option after option after option, but to make the forces conservative, it means that whatever path you take, the net energy change is going to be the same. And this is the fact that actually allows us to define a potential at all. A potential is basically, okay, if the energy you gain from going from point A to to point B, is always the same, then we could define a potential as the opposite of that energy gain, and the energy you have plus the energy of the potential will always be a constant.

0:44:55 Thomas: Right. Yeah. Yeah, yeah, yeah. Right. Right, yeah

0:46:27 Bryan: So this is where potential really comes from, and why it's not entirely a cheat is because the energy does depend on position, and really only on position, but not true when we have portals, because if we go back to our case of one portal on the ceiling, one on the floor, then imagine we take the banana example. You could go direct down to the ground, or you could go put it between the two portals, drop it into the bottom portal, let it fall through 10 times, then grab it out and move it to the final position. And those two cases are going to end up with different amounts of energy transferred to the banana.

The reason that conservation of energy breaks down isn't because we've lost time symmetry, although we could also do it if we lost time cemetery. It's because we've We've broken the other fundamental assumption, which is that forces are conservative or you could define a potential. We've basically broken the concept of potential energy. It's as if in a Fed example, we got fed up with all of this creative accounting and just invented, OK, here's your bank account. Your bank account looks like a portal. As soon as the amount of money in your account goes negative, you're back to $10,000 in the account. Well,

0:47:13 Thomas: Yeah. Huh, interesting. I, you know, there's, this is obviously complex and this could be hard to articulate, but there's a feeling in my brain somewhere that, it this just sound like restating the problem in some way? Like, I can't, I I can't fully articulate this, but part of me feels like we're just saying, oh, yeah, the reason this doesn't work is because it doesn't work. Like, is this really adding more explanation to us? Does that make sense? Sorry if it doesn'T. I can'T fully articulate why I feel that way.

0:48:20 Bryan: Yeah. Well, that's what a good mathematical proof does, is it just restates everything you already have, but in a more informative way. And Nutter's theorem is purely a mathematical theorem. It doesn't add any extra laws of physics. It just shows that things are already connected. And there are a lot of things that are tautological, which is just if the premises are true, the conclusions are necessarily true, but it doesn't mean it's not interesting. One useful example is what's called the anthropic principle, which is the very simple statement that life will only exist where it's possible for life to exist, which on its own doesn't really add much information. Transformation, but it is informative to think of it that way, because if you turn things around that simon tells you we shouldn't be surprised that life exists in a place where it's possible for life to exist, like we shouldn't be surprised that we exist on a habitable planet, life isn't going to spring up in into existence in a place where it's impossible, so we have to be careful that we don't take it as, well, it's like Christians, the argument from fine-tuning, they're saying,

0:48:28 Thomas: Ah, right. Okay. Yeah. Sure. Yeah, yeah.

0:49:41 Bryan: Well look how fine-tuned this environment is for us. Well, if it weren't fine-tuned, we wouldn't be here to be surprised by it.

0:49:48 Thomas: Yeah. So, I guess, okay. Refresh then. What were we trying to explain? You were trying to do your, you know, sort of your own personal calculation of why, what was the time or what?

0:49:57 Bryan: Yeah. Why we don't have conservation of energy in the portal universe, and yeah

0:50:02 Thomas: Oh, and so it's not, okay, so you were saying it's Not because time is not symmetrical, because in the portal universe, time, I guess is symmetrical, you're saying, but It's because of this other thing. And okay, so here's, I think here's where I'm getting a little hung up, is it sounds like the thing we are trying to explain is why do we gain energy when we take a different path? And then the answer is it's because we gain energy when we take a different path. Is that unfair of me to think? Like, if that kind of feels like what we're doing, what am I missing? Okay.

0:50:09 Bryan: Yeah Okay.

0:50:35 Bryan: Don't we have conservation of energy when we go through a portal? And I think the, I see it coming out, is what's actually changing is that we have, by introducing portals, we have broken the concept of an energy potential, and that you can only have an energy potencial if the change in energy is independent of path. That's basically the definition of a potential, is giving you the difference of energy between two points without caring about the path. And by introducing portals but still having gravity go directly down between portals, we've broken the concept that allows us to define a potential energy at all.

0:50:53 Thomas: Okay. Yeah.

0:51:23 Thomas: Okay, but, but in the world of portal, a portal that we do still have all of that stuff, it's just the portal kind of breaks it. Okay, so, I mean, it is kind of restating, but, like you said, it might be restating it in a useful way that kind of gives you more information about it.

0:51:38 Bryan: And like the more information here might be, If we existed in the portal universe, we couldn't do our mathematical calculations assuming a potential energy, which is something that if you're solving physics problems, you would do all the time. But in that universe, you don't have a potential. So if there's, yeah,

0:51:38 Thomas: Uh. Yeah. In the portal classrooms you'd be like, "All right, guys, folks, assume there's no portals, we gotta assume no portables to do these calculations, I know it's not the real world, but like," you know like teacher this isn't useful, I'm always gonna have portals, and I know, I know, but we gotta, this is how we do math here in this portal universe, universe.

0:52:07 Bryan: Yeah. We got to imagine this weird, crazy world without portals.

0:52:18 Bryan: Yeah, so there are ways you can get around and do all the math without a potential, but often a potential is the most convenient way to do it. But in Portal, they've broken that. It would make math a lot more complicated, but it doesn't cause reality itself to break apart, which is the fun thing. You could still do interesting puzzles in it.

0:52:35 Thomas: Yeah. Why it break time? When we go, is it that we're not actually traveling faster in the speed of light because space itself is just moving for us? Same way like the expansion of the universe doesn't violate that, even when it accelerates so fast that stuff might be moving away from us faster than the speedoflight?

0:52:56 Bryan: Well, there are a couple reasons for this. One is that the limitation of special relativity is only a local limitation. That all of the math assumes continuous space that doesn't have any holes in it. And you always have that locally. And even with wormholes, you have locally continuous space. So you can't travel faster than the speed of light locally. But you can take paths through it that allow you to take shortcuts.

Cuts, and now that those taking paths do allow you to maybe break time travel, and there have been a lot of people looking at this and trying to figure out, okay, we've established that faster than light travel is equivalent to time travel, so can we use this to send information back in time? And and so, so I was doing research on this, and so back in 1997, a theoretical physicist named Matt Visser came out with a paper saying, okay, if you set up multiple wormholes in this way, basically one wormhole out, one wormhole back, it certainly looks like, according to all the math I've done, that you could travel back in time, or at least with some relativity tricks, travel back in time.

And no one's been able to disprove it. This isn't an active area of research since it's so ridiculously impossible or improbable to happen. But Visser's conclusion from reading this is, well, other people have been looking at ways to travel back in time with wormholes. Like there was one idea a while back that you have two mounts of a wormhole, one stationary and one moving at a great fraction of the speed of light.

And so over time, the one that was moving would lag due to special relativity, and so you'd come out. But once we understood more about quantum gravity, we're able to show that that wormhole was unstable. And it really feels like the universe has some sort of property to it that prevents time travel. So although this model for now looks like it works, I suspect what this is really showing us is that we don't understand enough about quantum gravity to know why this is wrong.

Yeah, this is something amazingly humble for a scientist to say. You can can think of many people would say this, look, I've discovered a way to travel through time. He said, oh, okay, look, I discovered a away that would theoretically allow us to travel through time, but I'm probably wrong here.

0:53:36 Thomas: Yeah, yeah.

0:55:32 Thomas: Yeah. Yeah, interesting. So, I know where you plan to go with Portal, but I, okay. So in the quantum episode I did, we talk about quantum entanglement and information that can't be used for, you know, for different reasons, to transmit information faster than the speed of light. And during that discussion, um, uh, about how if you could do that, it might violate, I don't know, something like, it might allow some crazy, I don't know if it's time travel, but some crazy effect where like a cause could happen after an effect or something like that. And now I'm wondering if you just substitute in, instead of the quantum entanglement, implement using that to transmit information faster than the speed of light, if you just substitute in wormholes, why it be any different? Like if I'm in a ship and I take a wormhole forever out in the universe, and then, you know, now all of a sudden we can transmit, we can pass notes to and from, does that violate? And I'm wondering, like, if we were all worried about the quantum -y thing violating stuff, does that violate anything?

0:55:33 Bryan: Yeah.

0:56:24 Bryan: Well, So it's a bit complicated there, so if you listen to Matt Visser, he says yes, the math says you can, but that's ridiculous, there's probably something wrong with the math. Um, lot of other people have looked at it instead that, you know, if you look at all the laws of time and space very carefully, there's actually nothing prohibiting time travel that doesn't change the past. Basically, this is the Terminator One style time travel.

0:56:55 Thomas: Yeah. I like the like, like, well, we checked the bylaws and then you got somebody with a monocle looking at the scroll of the universe. Oh yeah. There's no rule. It says a dog can't travel back in time. As long as the dog doesn't play too much basketball and change the past. Okay.

0:57:00 Bryan: Yeah. Yeah, yeah. There's no reason John Connor can't send Kyle Reese back in time to, in the past, Father John Connor, who sends him back in time and creates this loop. And so there are people who believe it's possible to travel into the past, but it would only be possible in a way that would create a perfect time loop. And

0:57:18 Thomas: Yeah.

0:57:33 Thomas: It still would be where it wouldn't, you still have a bootstraps problem. How'd you get there to begin with then?

0:57:37 Bryan: That is part of it. One of the things you could use to get around of it is stop thinking of it so much as cause and effect and think of all of time as like one big tapestry that pre -exists. Exists. There are laws determining how one step in it gets to the next and how these can relate. It's like, imagine you have a big quilt before you and you have one rule.

Okay, every blue square must have a red square above it, then a yellow square, then back to blue. Now, you could take that quilt and you could cut one branch of it off, bend it around, and connect it to the bottom so that you get your blue, red, yellow pattern still following it, and you haven't violated any law of causality. You've just, okay, it always goes in this order, and it still does even though there's a loop here.

If time is really something that's pre -existing and we just have the illusion that we're traveling through it and causality is something we've invented to explain how past relates to future, then in some sense, time travel almost makes a little bit of sense.

0:58:51 Thomas: Okay. Well, Brian, we've time traveled, you know, but it's something like an hour into the future. And so now that we've done so, yeah, interesting. That's definitely not exactly what I imagined would be the physics of Portal that you would break down, but that's cool because, you could have been a really boring episode where you're like, like, yeah, no, that wouldn't work. But it wasn't. It's more like, yeah, look at what this tells us about how the universe works. And I think that's really cool. So the reason you don't have conservation of energy and different things and momentum, you explained all that. And let's see, what do we have in store for us for future portals? Is there anything else from Portal that you wanted to teach us that you didn't get to? Hmm.

0:59:33 Bryan: I do have one interesting aspect of it, but it actually comes from Portal Reloaded and just thinking about time travel portals and all of the fun you can get to there. But I think the one last thing I'll tell you is one of the reasons we can't go back and change the past is that if you want to change the past, that implies the existence of an extra dimension. Dimension.

0:59:59 Thomas: Yeah.

1:00:00 Bryan: Basically, time, you can think of going forward in time is changing how things are in space. And if you want to have two different versions of the past, like the grandfather paradox, you go back in time and kill your grandfather, you've got one version where he's alive, one version, where he dies early, then you've Got two versions, that means you must have an additional dimension. And

1:00:17 Thomas: What? How would the- how would a dimension do that? What would it- what would it do exactly? Is-

1:00:27 Bryan: It's basically space to allow differences to happen. Dimensions, yeah, time-like dimension, mostly.

1:00:31 Thomas: It like another- Time dimension or is it a spatial dimension? Okay, yeah.

1:00:39 Bryan: So if buy into this argument, then the reason we can't change to the past becomes rather simple. Because you can take the argument, if time travel can change tothe past, we must have extra time dimensions. And flip it around, take the contrapositive, if we don't have extra time dimensions, then time travel cannot change the past. And what are the chances our universe would be built with extra time dimension just in case Someone wanted to come along? And, you know, it's possible. You can build a video game with that, put in extra time and dimensions, but for a spontaneously arising universe that doesn't seem very likely. And so final thing I'll leave you with is that's probably the simplest explanation of why time travel that changes the past is impossible is we don't have the extra dimensions we would need for it to work.

1:00:39 Thomas: Yeah. Yeah. Makes- Sense. Well, let's get working on those. See if we can build them.

1:01:35 Bryan: Yeah. Yeah, see what we could do.

1:01:38 Thomas: Right, well, that was a lot of fun, um, forward to next time, uh, right, Dr. Brian Gillis. Hey, uh, your, uh, channel that people want to follow you.

1:01:45 Bryan: If you want to see more of me and check out me playing Portal Reloaded that's the fan sequel to Portal 2 with an extra time portal you can find me at Brian Gillis on YouTube that's B-R-Y-A-N-G-I-L-L-I -S I'll also be giving Bridge Constructor Portal a bit as well soon so come watch me try that out

1:02:04 Thomas: What's- That is- that another different version? Yeah.

1:02:08 Bryan: Not actually a fan game, it's an officially licensed game. The company that made these Bridge Constructors mobile games, you try to build a bridge that trucks can cross, got a license from Valve to incorporate portals. So basically, you build bridges that go through portals and do all the wacky things that portals can do, like these conservation momentum violations. Like you build a bridge which drops cars off into a portal below and shoots them out with velocity to try to get them across. It is very fun and wacky.

1:02:34 Thomas: Awesome. All right, we'll go check that out, out, everyone. And looking forward to next time, Brian. Until then.

1:02:45 Bryan: Right. Thank you for having me on, Thomas.