Daniel and Kelly’s Extraordinary Universe - Listener Questions 46: Mountains, ether and time!

Episode Date: December 26, 2023

Daniel and Jorge answer questions about reviving old theories, building tall mountains, and passing time.See omnystudio.com/listener for privacy information.

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Hey, Jorge, how are the mountains in Panama? They are wet and hot and beautiful. Wet and hot in the best possible way. That's right. Safest for work sense possible. Are they like tall mountains? Is Panama famous for having tall mountains? Sort of.

We're a pretty small country, but there is a pretty large volcano there. It's about 12,000 feet. Oh, wow. That sounds pretty impressive coming from like the Danish point of view. Are you from Denmark? My wife's family is from Denmark and we all speak Danish. Do they have mountains there?

You know, they think they have mountains. But the highest point in Denmark is like 500 feet above sea level. Oh, but the rest of the country is like 2,000 feet below sea level, isn't it? So it's a pretty big mountain relatively. No, that's the Netherlands. Denmark is mostly above sea level. Oh, right. Which makes it very flat and very nice to ride bikes around.

What's the biggest mountain in Denmark? They call it Himmelbier, which literally means the mountain of heaven. Whoa, how big is it? It's like 500 feet above sea level. I think the hill I live on. is bigger than 500 feet. Does that mean I live in heaven? You live in Danish heaven.

I live in California heaven. Valhalla. I am Jorge. I'm a cartoonist and the author of Oliver's Great Big Universe. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I love mountains in the summer. Oh, not in the spring or fall? Definitely not in the winter. Spring and fall can be acceptable.

Now, do you like to look at mountains? Do you like to climb mountains? Do you like to dig under mountains? How do you like to position yourself relative to a large rock? I like to be in the mountains in the summer. It's beautiful and the fresh air and hiking and the views and all that stuff. In the winter, I prefer to be far away from the mountains. though I do enjoy looking at them, you know, out of the window of an airplane.

But doesn't that require you to get out of your couch? Isn't that the problem here? I have no problems getting off my couch in the summer. I love going to Aspen and I love the Rockies. But man, in the winter, that is just not fit for human habitation. I see. So nine months a year, we can find you in a couch. Three months a year, you're up in a mountain.

It's a pretty good life. That's my personal Valhalla. That's right. It's called tenure. You just disappear into a mountain. When you get tenure at University of California, they actually give you a couch. Not a mountain. Not a mountain, no.

There's a lot more couches to go around than mountains. Just a mountain of paperwork. But anyways, welcome to our podcast, Daniel and Jorge, Explain the Universe, a production of IHeart Radio. In which we climb the mountain of mysteries that we have about the way the universe works. We want to take everything apart and understand how it all interacts, how those little particles push and pull on each other, how they dance together to make the reality that we're aware of

and how they build themselves up into mountains and planets and solar systems and galaxies and the entire universe that we one day hope to understand and explain to you. That's right. We stand on the shoulders of giants to get a better view of the entire cosmos, hopefully getting a little bit closer to the stars and what makes them turn, what makes them shine, what makes them explode, and what will happen to them in the far off future. One of the most incredible things about physics is that those questions about the stars and the questions under our feet can often be very closely related. They might even be the same.

The same laws of physics that tell us how the stars move and how they orbit each other and how the universe develops should be applicable to the rocks and the bananas and the white chocolate and everything else that we find around us. Especially ever you live on the sun, that would be the same physics, right? That's right. Solar Newton probably had that realization a lot earlier than ours. Yeah, yeah. He was probably sweating the details of living.

on the sun. My favorite model of how the sun works is actually Gary Larson's model. Oh yeah? What did he say about the sun? Well, he has this awesome far side cartoon where it's just like a sweaty guy inside the sun and he's got a big lever that says rise or set. I think he had a degree in biology, not astrophysics. No, obviously that makes no sense because if you're inside the sun, what do you do to rise and set, right? That's your quibble with the cartoon? It's like the direction of up and down. Not the person living inside the sun pulling a lever. need one lever for every planet, right? How do you rise over Jupiter instead over the moon? And yes, that's my quibble with the science of the far side. Maybe he was pulling the earth lever.

I think there's a lot going on in that cartoon at the same time. It's got layers. But speaking of layers, there are many layers to the earth. Some of them go pretty high, which gives us a view of everything that surrounds us and makes us all ask questions about how things work in the universe. It's just part of being a curious human in the world to wonder how everything works, to look for explanations, to try to tell stories about the universe that makes sense to us. That's what we try to do with the cutting edge of science. That's what we do here on the podcast. And that's what we want you to do when you are going about your lives. I want you all to think like physicists and wonder, hmm, how does that work? Or do I really understand how these two ideas come together? And do I

really want to climb that mountain in the winter? No. No, I want to take a helicopter to the top. That's what I want to do. I do like mountains in the winter. That's when you can ski and snowboard. You say that like those are good things. I don't understand. Yeah, you're super fun. What's not to like about strapping some planks on your feet and then jumping down a mountain?

Yeah, it's cold, it's expensive, it's dangerous. What couldn't you love? The thrill, the fun, the outdoor activity of it? I get that on the 405 every day around here. Well, there you go. You should just take the 4 or 5 to the top of the mountain. But anyways, people do have questions. We all have questions about the universe, about how things work around us.

And sometimes we answer those questions on this podcast. We encourage you to think deeply about the nature of the universe and to write to us when you are confused or you want insight. We answer all of our listener emails. Please send your questions to questions at danielanhorpe.com. So today on the podcast we'll be tackling. Listener questions. Number 46.

couch surfing edition. I'm pretty sure nobody who's asking these questions has visited the sun, for example. Well, how do you know, Daniel? Do you know all of our listeners? I don't know all of our listeners. And their travel experiences? But I know that nobody has visited the sun. So that rules out everybody, including our listeners.

How do you know, Daniel? Or how do you know there aren't any aliens listening to this podcast? Oh, are we doing that kind of podcast today? I don't know. Extreme skeptic edition. How do you know, Daniel? How do you know? How do you know I'm even Daniel today if you're going to be really skeptical?

That's right. How do I know you're not the alien? Or I could be my brother Shimon. You know that my mother can't tell us a part on the phone still after 50 years. Oh, boy. Oh, are we getting into the dynamics of you and your brother again? Let's answer some listener questions. Yes, let's get back on track here.

Our listeners have questions. And sometimes we answered them here on the podcast. And today we have three pretty awesome questions. One of them is about the biggest mountain possible. The other one is about the Higgs field, and the third one is about time. And can it go faster or slower depending on where you are? So let's jump right in. Our first question comes from Nicholas.

Hello, gentlemen. This is Nicholas from Sweden. Is there a limit on how high a mountain can become on Earth before physics limits it? When the base of the mountain grow larger and larger, does the curvature of Earth affects the height? Awesome question from Nicholas. Now, do you think Nicholas knows the difference of where Vikings come from in Scandinavia? I'm pretty sure Nicholas has a good grasp on his own history, yes. Did the Swedish count as Vikings?

I think I've been there and I think I did see a Viking ship there, right? Yes, the Danes, the Swedes and their regions all have Viking ancestry. The Finns are different. They're Nordic, but not Scandinavian. But did they have Vikings too? I mean, I'm sure some people who live in Finland today have Viking ancestry. the way people who live in like Sardinia have Viking ancestry because the Vikings went everywhere

and did horrible things to local people. But the Viking culture itself is more Scandinavian. Now where does Thor come into this? Was Thor technically Swedish, Danish or Finnish? Thor is part of Scandinavian folklore. So yeah, that would be Danish, Swedish, Norwegian. Well, I'm glad we cleared that up on our podcast, Scandinavian culture and history and mythology.

those countries all speak very similar languages, like if you speak Danish, you can understand Norwegian. If you speak Swedish, you can understand Norwegian. If you speak Swedish, you can understand Norwegian. Norwegian say they can't understand Danish, but we know they can. But a big difference between these countries is that Norway and Sweden have mountains. Denmark doesn't really have any. But anyways, back to physics on our question. Nicholas from Sweden has a question about how high a mountain can be on earth before there are physical limitations to it. Like, is Is there no limit to how big a mountain can be? Or is there a point of which the mountain just can't grow?

This is a really fun question. I love this question because there's lots of different ways you can answer it. You can answer it like a physicist or you could try to answer it like a geologist. And it shows you how different sciences think about different things and how all science is like about building models that kind of apply to the real world and have limitations. But wait, do you get different answers if you answer it as different scientists or do you come to the same conclusion. I would hope the same answer. You tell very different stories and you sometimes get roughly the same answer. Oh boy. This is going to depend on the definition of a

mountain now or like the definition of height or size. Like all of science, it's going to depend on what you include in your description and what you don't. So for example, if we're going to take a physics point of view, the physicist in me says, let's just think about a mountain like a big cone of rock and let's ask what's the tallest pile of rocks with the biggest cone. you can build where the top doesn't have so much pressure that it like crushes the bottom. Think of it like building a skyscraper. You're saying that if I just pile a bunch of rocks or dirt, at some point the weight of it is going to be so much that something's going to happen to the bottom of it.

Exactly. Rock is not infinitely strong, right? You make a super tall tower of rock and the pressure on the bottom rock is going to be so great that it's going to start to flow. It doesn't have to melt. It's not necessarily going to become liquid, but it will start to flow because the pressure. is so great. This actually happens already inside the earth in the sort of upper layers of the earth. The rock is not melted. It's not liquid, but it does still flow because of incredible pressure.

So all materials have something called compressive strength that if you push on it hard enough, it will flow or crumble. Right, but that assumes it has somewhere to flow, right? Yeah, that's right. Like if it can flow, it can be pretty almost infinitely compressible. Yeah, in this case, though, if you're building a mountain, then what's going to happen is that your mountain's base is going to flow and it's not going to get taller. So as you add rocks to the top, you're going to be adding pressure on the bottom and the bottom is going to flow and spread out. So there's a sort of physics model there that can help you calculate like what is the

tallest pile of rocks you can make without the base spreading out from underneath you. Right. I guess maybe it does maybe come down to the definition of a mountain, which is like a pile of rocks above some arbitrary level that you pick to be the base of the mountain. Exactly. And so if you define a mountain like that, you have a flat plane, you start by piling rocks and you build those up and build those up, then it's a pretty simple model. And the answer you get for like, what is the tallest pile of rocks you can build? Depends on just a couple of things.

It depends on the gravity because the more gravity there is, the more pressure there's going to be on the bottom, right? In a no gravity environment, there's no pressure. In a higher gravity environment, there's more pressure. And it also depends on the compressive strength of the material. Like if you build it out of titanium or you build it out of popcorn, you're going to get a different height mountain. But just really those two numbers are all that it depends on. Well, I think there's something in civil engineering where there's sort of like a maximum angle that you can pile a bunch of rocks or a bunch of dust or a bunch of a powder. And so I think what you're saying is that at some point, if you just start piling rocks, at some point the bottom rocks are going to flow outwards to the sides, right?

Exactly. And that's kind of why like a pile of rocks looks like a triangle, basically, right? Yeah, that's exactly right. And the more stuff you put into it, the more it's just going to basically fall off to the side and roll down the side of the mountain. And this is a very simplistic model, right? But we're ignoring everything happening under the surface of the thing that formed the mountain, right? Nobody actually builds mountains this way, starting with a pile of rocks and adding them one at a time. But in this simplistic model, you can plug in the numbers and say, how tall could you make a mountain out of grand?

it, for example, if you had the gravitational force of the Earth. And the answer you get is about 22 kilometers high, which, you know, for a physics model is pretty good. Like, it's order of magnitude the right answer. Interesting. Meaning you plugged in the numbers and you got 22 kilometers. But what does your model say happens after 22 kilometers? After 22 kilometers, then as you add rocks on top, the bottom breaks down and it spreads out.

So it basically maxes out at 22 kilometers. Like you add another rock and the base gets wider. Yeah, exactly. So you can get a higher volume to your mountain, but you can't get a taller mountain. Oh, I see. So the more rocks you add, the just the wider would get. Yeah, you get a fatter mountain, exactly. But again, this depends on a totally flat world, right? Yes, it depends on a totally flat world. And it also ignores the way we know that mountains are made, right? In reality, mountains are not made by people piling rocks on top of a flat plane. they're made by tectonic plates slamming into each other with certain force and certain speed

and then one of them subducting under the other forcing it up to create those mountain ranges like the tallest mountains on earth Everest come from the Indian plates slamming into the Asian plate and creating the Himalayas but pushing the rocks up pushing some of the rock up exactly and for a long time in geology there's been a debate about what limits the height of mountains some people arguing that it's the pressure from the tectonic plates and other people arguing that No, it's actually erosion because, you know, weather and water and rivers and wind and all that stuff breaks down mountains eventually. So for a long time, people were arguing about which of the two factors controls the height of

mountains. Well, there's also in geology buoyancy, right? And at some point when you pile enough rocks, it starts to sink into the earth. That's true. But here you have two plates pushing on top of each other. And so one place is being pushed up by the other plate. One is sinking down and one is getting pushed up, right? So I'm not sure that buoyancy is a factor.

I just read a paper in nature that came out last year that showed that the height of mountains around the earth is totally correlated with the pressure between the plates. Like you can measure the forces along the two plates and they show that the greater the pressure between the two plates, the taller the mountains, which suggests that actually erosion is basically irrelevant. And the only thing that determines the heights of mountains on earth

is how hard these plates are slamming into each other. Or maybe that's the biggest factor though, right? Yeah, that's the overwhelming factor to within their Arabars. Right, right. And that means that if you wanted a taller mountain, you need, like, India to zoom faster along the surface of the earth before it slammed into China because it would apply a greater pressure and make taller Himalayas. Right, but once you form a mountain, I think another limiting factor is, like I said,

the buoyancy of it, right? Because the rocks inside the earth are sort of soft in a geological scale. And so at some point, the mountain is going to sink into the earth. Yeah, I think that in reality, there's lots of things that all contribute. But in the end, we can never model all the processes that control these things. So we try to just isolate what is the dominant factor. Then this nature paper claims that it's the force between these two mountains. And that's really cool because it makes you think about like what might have happened earlier on earth.

Like when the earth was hotter than the convection cells within the earth were probably cycling faster, which might have meant plate tectonics or pushing things together harder, which might mean that there were taller mountains on earth earlier on. Right, right. But I guess this is, I think you're talking about the origin of mountains and, like, here on Earth, this is how mountains were formed. Maybe they're correlated to the pressure between the tectonic plates. But I think Nicholas' question is, like, what's the biggest one you can form? Yeah, good point. And there, I guess, physics says 22 kilometers is the tallest mountain you could make on Earth without the base of it flowing out from under you. And as you say, there are also buoyancy effects. So I would guess somewhere around that number, around 20 kilometers. And then he also had a bit of a question here about the curvature of the earth. How does that affect your calculation? Because your calculation assumes a totally flat earth.

Yeah, but on these scales, even a mountain is pretty small compared to the curvature of the earth. So your mountain would have to be like really, really huge before the curvature affected it. So I think that in every case, we can basically ignore the curvature. Well, I guess maybe the question is, what would happen? Like if I took the moon or maybe a whole other planet, I pulverized it into rocks. And I just started pouring those rocks in one place on Earth. It would at first start to make a mountain. And then at about 20, you're saying it out about 22 kilometers,

the more rocks I pour into, the more it's just going to flow to the sides. Yeah, exactly. And then what's going to happen? Is the Earth going to end up kind of oblong shape? Like a cone head? Yeah, I mean, eventually it would grow wide enough that it just becomes a feature of the Earth, right? Because the Earth varies in radius by more than 20 kilometers. All right. Well, I guess that's the general answer for Nicholas. Daniel says that according to his model, the biggest mountain that you can get on Earth would be about 22 kilometers above sea level.

But that's a simple physics model. It ignores lots of stuff. So before you submit a pitch to the U.S. government to build the world's tallest mountain, please get a more accurate model. All right. Thanks, Nicholas, for that question. So let's get to our other questions here about the Higgs field and the flow of time. So we'll dig into those. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled.

metal, glad. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice.

system on the iHeart radio app, Apple Podcasts, or wherever you get your podcasts. A foot washed up a shoe with some bones in it. They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases, but everything is about to change. Every case that is a cold case that has DNA. Right now in a backlog will be identified. in our lifetime. A small lab in Texas is cracking the code on DNA. Using new scientific tools,

they're finding clues in evidence so tiny you might just miss it. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha. On America's Crime Lab, we'll learn about victims and survivors, and you'll meet the team behind the scenes at Othrum, the Houston Lab that takes on the most hopeless cases, to finally solve the unsolvable.

of the unsolvable. Listen to America's Crime Lab on the Iheart radio app, Apple Podcasts, or wherever you get your podcasts. When your car is making a strange noise, no matter what it is, you can't just pretend it's not happening. That's an interesting sound. It's like your mental health. If you're struggling and feeling overwhelmed, it's important to do something about it.

It can be as simple as talking to someone, or just taking a deep, calming breath to ground yourself because once you start to address the problem, you can go so much further. The Huntsman Mental Health Institute and the Ad Council have resources available for you at love your mind today.org. Have you ever wished for a change but weren't sure how to make it? Maybe you felt stuck in a job, a place, or even a relationship. I'm Emily Tish Sussman, and on she pivots, I dive into the inspiring pivots of women who have taken big leaps in their lives and careers. I'm Gretchen Whitmer, Jody Sweeten. Annika Patton. Elaine Welterah. I'm Jessica Voss. And that's when I was like, I got to go.

I don't know how, but that kicked off the pivot of how to make the transition. Learn how to get comfortable pivoting because your life is going to be full of them. Every episode gets real about the why behind these changes and gives you the inspiration and maybe the push to make your next pivot. Listen to these women and more on She Pivots, now on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, we're answering listener questions here today, and our next question comes from Martin. Back in the 17th and 18th century, it was believed that there was an ather which permeated the universe. This, of course, has now been disproved. However, fast forward many years, and scientists have shown that there is a Higgs boson field, although no,

not exactly the same. They do seem to be quite similar. My question is, are there other theories in the past that were disproved, but are actually similar to theories or proofs that we believe to be true today? All right. Great question here. Going a little bit back in history about our ideas of what the universe was made out of. We used to have this idea of the ether in our cosmos, right? Yeah, the ether was an idea which was popular for quite a while to try to explain the mystery of what is light wiggling through we understood sound waves were wiggles in air and there were other kinds of waves and there were waves in the ocean and the idea that light was a wave raised the question of like what is light wiggling through and so for a long time

people imagine that space wasn't actually empty it was filled with something the ether that light was propagating through sort of like you know we have air around us here on the surface of earth and sound waves are really just you know pressure waves through air. Yeah, that's exactly right. And the speed of those waves is relative to the air. That's the medium. And so you can like catch up to a sound wave and move with it, for example, as it moves through the medium. And so there was this idea that maybe light worked the same way as sound, like maybe light is a wave that is being spread by something that's all around this. Yeah, exactly. And this was like a universe-sized idea that all of space was filled with

this stuff we hadn't ever discovered before. And then later the idea was, discarded. And ever since then, this idea of an ether is sort of mocked in popular science a lot. You know, anytime you suggest anything that fills the universe, people are like, well, well, that sounds like the ether revisited. Ha, ha, ha. We know how well that worked out. Oh, boy, I didn't know if it says we're so snarky. Well, I think there's an element to Martin's question, which is like, is this idea of a Higgs field, which fills the universe? Is that just the ether revisited? You know, like, should we be concerned about inventing ideas of stuff filling the universe because that didn't work out well

for us once. But then later you sort of built quantum theory, which sort of relies on an idea that's very similar to either, right? Quantum fields. Yeah. So to put a pin in the story of the ether, the reason we didn't believe the ether exists is because light doesn't move through space the way sound moves through waves, right? Sound moves at a constant speed relative to its medium, but light moves at a constant speed relative to any observer. So the Michelson-Morley experiment showed that light can't be moving through the ether, because as we move through the ether, we measure light to always have the same speed. It turns out that light just propagates through space, actually to propagation through these

quantum fields. So as you say, we have this sort of like new updated version of the ether. Instead of imagining the universe is filled with stuff as a medium for light to propagate through, we say that light propagates through space itself as fluctuations in the those quantum fields. But importantly, and this is the big difference, those fields don't have a frame of reference like air does. So you can't catch up to a photon. Photons are always moving at the speed of light relative to the observer. I wonder if you're sort of getting up to our, you know, limits of knowledge because you're talking sort of about relating relativity, right?

And relativistic speeds to quantum theory and quantum fields, which have the, has this actually been able to relate the two? So physicists cannot relate to general relativity, which is about the curvature space and gravity to quantum fields. But we have successfully married special relativity, things moving really, really fast and even at the speed of light to quantum fields. And so quantum field theory is fully special relativistic and incorporates speed of light transmission and particles moving at the speed of light, all that stuff. So we have a very robust theory that unifies quantum mechanics and special relativity. Meaning that these ideas that you can't go faster than the speed of light, that's built

into quantum physics. Yeah, that's built into quantum physics, exactly. And quantum physics tells us this fascinating picture of the universe, which sounds kind of familiar, like, hmm, the universe actually isn't empty out there. Space is filled with all of these quantum fields. There's lots of them. There's the Higgs field, but there's also the electromagnetic field and the electron field and all the cork fields and maybe fields for dark matter, we don't know.

But space is filled with all of these weird quantum fields that are sort of reminiscent of the ether in the sense of like, oh, space isn't empty. There's stuff out there happening. And so I think Martin's question here is like, you know, we used to, now you sort of, it seems like you make fun of people who believe in the ether. But at the same time, now you believe that there is something sort of like the ether that you call quantum fields. And so I think his question is like, are there other examples of that? like are there things we thought was right but then disproved but then later it turned out to be well it's sort of like this yeah it's a great question and it reminds us to be humble right that things that we like chuckle at today in the future people might be like hmm actually that was a

good idea and you should have pursued that a little bit more yeah like maybe you'll try skiing one day and like it and you'd be like oh my god i should have been doing this for years yeah maybe i'll learn how to ski at the speed of light that'd be awesome yeah of course of that it would take no time to do it. So see, like you would suffer very little. Perfect. Another really great story about the dismissal and the resurgence of a big idea

is also connected to relativity, but this is general relativity, and it's the idea of the cosmological constant. You know, Einstein, when he was developing his theory of the universe, how space is curved and how gravity is actually just the motion of stuff

through that curved space instead of a force, he put together his theory of space time and he looked at it And he realized, hold on a second, if this is true, the universe has a bunch of mass in it. Why isn't the universe just collapsing? Why isn't space getting curved in a way that everything just rushes together and collapses the universe? And he looked out in the universe and he thought the universe was static. He thought all the stars just sat out there in space forever.

So he added a fudge factor, a cosmological constant to the equations of general relativity to balance out the effects of mass and hang everything sort of on balance in place. he just made it up like he's like oh this is weird I'll just add a number here yeah it turns out if you add a number you avoid this disastrous prediction of the equations

and only a few years later he realized that that was sort of silly and unnecessary wait what do you mean he realized that he didn't need that constant or did other people think you didn't need it no he realized that we didn't need that constant

and he actually called it like a huge blunder later in life what do you mean you didn't need it like what was his mistake well he was trying to describe a static universe, a universe where nothing is happening. There's no expansion. There's certainly no acceleration. And this is kind of a crazy theory anyway, because it predicts a universe sort of like balanced on a knife edge, you know, a little bit more matter and things would collapse, a little bit more cosmological constant and things would expand. So it wasn't really

anyway, a great description of the universe as we saw it. And then a few years later, Hubble discovered that it anyway wasn't the universe we were living in. The universe wasn't static. It was expanding, right? this positive expansion of the universe. So Einstein figures, oh, well, you don't need the cosmological constant to balance the mass. You just have this positive expansion already. The universe somehow began with this expansion and the mass isn't enough to overcome that. And so that was Einstein's picture of the universe to accommodate what Hubble and lots of other people, of course, discovered that the universe was already expanding.

And so if you find out that the universe is expanding, then you don't need that fudge factor. You can just explain that without it. Yeah. If the universe is expanding, then without that fudge factor, you have two options. Either we'll never collapse because the expansion is so fast or we just haven't collapsed yet because enough time hasn't passed for gravity to pull everything back together. So that was sort of Einstein's new picture and he got rid of the cosmological constant. I see. He was like dope. He was like, oh, I didn't need that. That was a mistake.

But then decades later, it resurfaced. And now it's a crucial part of our understanding of the universe. What do you mean? What changed? Well, in 2000, we discovered. that the universe isn't just expanding, it's expanding and accelerating. The expansion is happening faster and faster every year. Remember Einstein's description of what was happening is, all right, there's some expansion, but it's slowing down because of gravity, and either it's going to peter out and turn around to come back to a crunch, or it's just going to sort of drift out gradually forever.

But then we discovered this expansion isn't slowing down. It's speeding up. And in order to make that happen, what do you need? You've got to put back in the cosmological constant to make that acceleration happen. What? So without the fudge factor, then you just get a universe that's evenly expanding. Without it, you get a universe whose acceleration is either zero or negative. You need the cosmological constant to have positive acceleration to the expansion.

And that's not to say we understand why that's happening. It's just like, can we even use the equations to describe what we see? And to do that, we need Einstein's fudge factor to return. And is that the official name of it, Einstein's fudge factor? EFF, no, goes by the much fancier. name of the cosmological constant. But the cosmological constant is just a number. We put into the equations to describe the universe. Again, we have no explanation for it, no mechanism that can describe it or predict it. Our attempts actually to calculate what the cosmological constant might be

from the quantum fields that fill space give an answer that are off by 10 to the 100. So we're nowhere near understanding why this constant has its number. Interesting. So that's kind of another modern day version of the either. Are there any other concepts like that in physics? They're all over the place. Another famous one is string theory. String theory actually originated as an attempt to describe how quarks interact. Now we describe quark interactions using the strong force and we have a really nice theory

of it called quantum chromodynamics, which explains the fields involved and the gluons and all that complicated stuff we've talked about on the podcast. But originally in like the 50s and 60s, people were trying to use string theory to describe the strong interaction. But it didn't really work very well. And in 1973, when we discovered the J-Psi particle, which is a bound state of two quarks, that was really a triumph for this other idea, this quantum chromodynamics theory of the strong interactions. So people abandoned string theory. They were like, ah, string theory, total failure, couldn't explain the strong interactions. And then about 15 years later, people realized, oh, actually, there are things you

can do to string theory to make it to be able to describe not just the strong interaction, but every kind of interaction, maybe even gravity. Then you had the string theory revolutions of the 80s and 90s. And now string theory is everywhere. It's like the best candidate for our theory of everything. So it failed to describe one little thing, but then people figured out it can describe lots of other things. But doesn't it still fail to describe the one thing that it had failed to describe before?

One of the challenges of string theory is that there's lots and lots of string theories. And so they thought initially that there was a basic problem with string theory that it couldn't describe the strong interactions. but that's because they hadn't yet considered, like, the right string theory. And so other people found ways to, like, put constraints on the strings and add bells and whistles to them that allowed them to describe accurately the strong force and all the other stuff. The problem is, of course, we don't know which string theory is the right one, and we can't test it. So it's not like string theory is proven, but it's definitely a deep area of research where it was

once abandoned. Right. It's exciting. It's maybe because of its potential, but we don't really know if it's true, which was sort of Martin's question, like, is there something we thought wasn't true, but now we think it's true? Yeah, that's fair. We definitely don't know that string theory is true, but it's no longer on the dustbin of theories. All right. Sounds like physics is constantly changing, right? And things that, ideas that we thought were working, we would turn out to work and things we thought

work sometimes don't work. It's a process. It's definitely a process. And we're constantly minding the past. If you look at the history of physics, there are lots of scenarios where like nothing happens for 40 years and then somebody reads an old paper and they're like hold on a second this is a great idea how come nobody's doing this and sometimes ideas just need their moment the right person or read them at the right time and connect them with current thinking so we're constantly digging into our own past to look for good ideas that we've ignored make physics sound kind of fashionable and fickle absolutely remember physics like all science is of the people by the people for the people it's not like methodical or consistent in the way that it explores all ideas

It's just like, what are people into? What are they thinking about? What ideas do they have? What inspires them? It's a creative process. What's trendy? Now, would you spell fickle with a pH then? Or fashionable with a pH, P-H-H-I-O-N?

You're in charge of the names, so I defer to you. Good. Thank you. I'll take that title. All right, well, let's get to our last question here of the day, which is about the flow of time and universal symmetry. So let's dig into that. First, let's take another quick break.

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but then we realized were true or sort of true and it sounds like there are oh absolutely and it sounds like physics is always changing and so that was the answer for that but now we have our third question of the day which is about time Hello, Daniel. Hello, Jorge. I'm looking for a place in the universe where time go way faster related to the outer environment of this place. Is there a place like that? What can make this place real? I thought maybe some gravitational or a different speed effect can cause it. What do you say? Thank you. Here, Nadav from Israel.

All right. Interesting question. I'm not 100% sure I understand it, but it sounds like they're asking, can you somehow make time go faster? I think he wants like a box. He can step in where things will go much, much faster than when he steps out. Less time will have passed on the outside than on the inside. More time, I think. Like, I think what he's maybe referring to is that, you know, a lot of the ideas we have about time, they're about slowing down time, right? Like if you go close to the speed of light or really fast,

then time will slow down for you. Or if you go near a black hole, time will slow down for you. I wonder if he's asking, you know, is there some sort of effect In physics, that we'll do the opposite and make time go faster. Yeah, it'll go faster for the people like in the box, right? So the people step in the box, they're in the box for a year in our time, and they come out and 100 years has passed for them. That's what he wants, right?

Right, right. So time moves, more time has gone by for them. They're older. Yeah. Time has flowed faster inside the box and outside the box. Right, right. Yeah, it's a good question. And you're right that this is not something that's easy to assemble in physics, not something we

naturally see, but we should dig into like why that works and how that works. But I do have an idea for a dove, though I think it's probably impractical. Well, impracticality has never stopped physicists. So why start now? Exactly. All right. So we're looking for a way to accelerate time. Maybe like if you wanted to age your wine faster, you could stick it in this box and it would get older faster. Or if you wanted to grow your vegetables faster, I guess it's one of the use for it. Yeah, absolutely. Or chemical reactions. could happen faster. You could, like, make new fossil fuels in the blink of an eye rather than waiting 100 million years.

Yeah, there you go. Or if you wanted to, like, worn jeans, but you didn't want to wait and be fashionable with a pH, you could use this machine. Yeah, or you could roast a Thanksgiving turkey in a minute, right, instead of hours. Oh, my gosh. That is the actual killer app for this. Fast, slow, organic food. There you go.

Physics saves Thanksgiving. Yeah, there you go. All right. So what's your idea for making this happen? So first of all, why is it that we can only usually slow down time in the universe? Well, there's two different kinds of ways to change how time flows. One of them is based on speed, velocity, and that one's symmetric. And then one of them is based on gravity, the curvature of space.

And that one is asymmetric. So the velocity one is the one people mostly think about. This is like if you see a clock moving past you really fast, you're going to see it ticking slower than your clock. Right? So Jorge's in a spaceship. He's flying by the earth. He has a clock. I'm watching his clock from the earth comparing it to my clock. And I see Jorge's clock is ticking slower. So Jorge's time is passing slower. Right. It's going slow for everybody, which is weird. Yeah, because it's symmetric. You might think, well, if Daniel is seeing Jorge's clock going slower, doesn't that

mean Jorge is seeing Daniel's clock going faster? The answer is no, because Jorge also sees Daniel moving fast. Like, if you're in the spaceship, from your perspective, the Earth is flying by you at high speed, and the same rule applies, moving clocks run slow. You see my clock moving fast, so you see my clock ticking slower. So I see your time moving slow. You see my time moving slow. nobody sees anybody's time moving quickly.

And that's the whole puzzle of special relativity and the twin paradox, which we dug into other times on the episode. But that doesn't give you any way to speed up time. Well, maybe let's dig into it a little bit. So that's just how it looks to the two of us for each of us as we pass by each other. But at some point, if we wanted to meet up again, one of us has to turn around. And for that person, time is going to move slower or faster, right? So if you decide to turn your spaceship around and come back.

to Earth so we can compare our clocks like right on top of each other without any velocity relative to each other, then the rules of special relativity don't really apply anymore because when you turned around, you accelerated. And this simple description of special relativity only applies to things moving at constant velocity. When you turn around, that's acceleration. But you're right, that something interesting happens when you turn around. When you turn around, you see time jump forward for me. So so far you've seen my time be slow when you turn around as you turn around that acceleration has this effect that you see my time jump forward so that when you come back to earth our times are very similar to each other right but like we're saying

there's something called the twins paradox which is like if you take two twins and you send one of them to the next star system going at almost a spute of light and then they come back one of the twins will have aged faster than the other that's right so the one that takes that trip that goes on the spaceship accelerates turns around comes back will be younger than the twin that stayed on earth so like yeah so like if you went to slow down time for yourself, you would hop in a spaceship and go away, right? Yeah, that's right. So to make time move faster, wouldn't I stick everybody else in a spaceship, send it off, and then have it come back, and then I will have age more?

I guess maybe the question is, like, why is it so one directional? Or is it one directional? Like, what's the difference, twin A and twin B? The difference is the acceleration. While velocity is totally relative, it doesn't matter who's doing the moving. it just matters what you measure, right? There's no absolute frame of reference. Acceleration is not relative.

So there is a difference between the twin that goes out in the spaceship and turns around, that's acceleration, and the one that just stays on Earth and doesn't accelerate. So the effects of the flow of time are different on those two twins. That's why they're no longer symmetric. In the case where they're just passing each other in space, they both see the other one's time is going slowly. And that's perfectly symmetric because they just have relative velocity. Nobody's accelerating.

one of them turns around then they're accelerating and that makes one twin very different from the other twin from a physics point of view and that's why they have different outcomes and that actually is an idea there it's like well if you accelerate then you see time jump forward for everybody else and so that's actually a way to accelerate the passage of time for the rest of the universe right right that's what I mean it's like accelerate send everybody else on earth and on a spaceship and have it come back that's a little bit logistically hard and it connects nicely with the other time dilation because Because as we've talked about on the podcast before, acceleration is just like another way to see curvature in space. From a general relativistic point of view, acceleration and curvature are basically the same. You can even like create an event horizon with acceleration. Remember we talked once on the podcast about how you can like outpace a beam of light if you're constantly accelerating. And so this connects with the other kind of time dilation we can talk about. And that's absolute time dilation due to curvature. If you see a clock near a black hole, for example, you will see its time going slower.

But if somebody's at that clock and they're looking back at you and you're far away from the black hole, they don't see your time going slower. They see your time going faster. In the same way that like the twin that's accelerating sees time moving faster for everybody, a twin near a black hole will see time moving faster for everybody else outside in the universe. So this is asymmetric time dilation because curvature is not relative. curvature is absolute just like acceleration is it's really the same thing so like for example if you want it to make time go faster for yourself you might go off into orbit right because the earth is

also creating some curvature and time is moving slower for things closer to the center of the earth right that's right if you're further away from the earth then your time will be moving faster so like a way to age your genes faster or your wine is to send it into space or send it far away from the earth yeah that's right so if you're hosting thanksgiving you should host it near a black hole so you can send the turkey away from the black hole so that its time can move faster while it's cooking. Right, right.

But I guess what I'm saying is you don't need the black hole, you can just do it here on Earth. Yeah, that's right. And it's a pretty small effect because the Earth doesn't have really dramatic curvature. Right, right. But the big picture we're sort of stumbling towards here is that for time to go faster,

you need a place with less curvature. And so if you want everywhere in the universe to pass time slower than like your box, You basically need everywhere in the universe to be near a black hole or be near high curvature except for your box. So like my very impractical idea, similar to your impractical idea, yours was make everybody in the universe accelerate except for the turkey or whatever. Mine is fill the universe with black holes except for where the turkey is and then time will pass faster for the turkey than everybody else. Right, right. Or just shoot it with a turkey gun onto the sky.

Although you won't get that much of an advantage. But I think maybe to answer the question of our listener, the answer is sort of like, yes, sort of. Like if you want time to go faster than how it does here on the surface of Earth, then you can do it by putting it in a box and sending it off into space for a while, right? Time will move inside that box faster for a little bit. Yeah, the same way that time near a black hole moves more slowly, time near the surface of the Earth moves more slowly than it does out in deep space.

So basically, our time is already slowed down a little bit. And you could take advantage of that by launching something into deep space where that effect isn't happening and its time will go faster. Right, right. So if you wanted to just age faster than everybody in the surface of Earth, that's doable. But I think maybe the question he had was, can you accelerate time where there's no curvature or where there's no black holes or a planet?

Like at the baseline speed of time in the universe, maybe out there whether you're nowhere near anything massive, can you make time go faster than that? We certainly don't know the answer. to that question. Current physics would say it's impossible, but we also know the current physics doesn't really understand what time is or what space is, whether they're fundamental or whether they bubble up from something deeper or like a theory of quantum gravity, like maybe string theory. So we don't really understand what time is. So if I said absolutely not, then in 50 years,

somebody would be like, ha ha, that guy didn't know what he was talking about. Right. And we know how snarky physicists can be. They would totally laugh at you. Oh, man, they're the worst. They go on these ski trips. They laugh at each other over hot cocoa. It's terrible. That's right. They're like, that Daniel, it doesn't know what he's missing. So current physics doesn't have a solution for you, Nadav,

unless you want to fill the universe with black holes or launch things into space. Right. Or accelerate everybody else. Although it made me think, like with the twins paradox, right? Mm-hmm. I send the twin out into space. They come back. They have age slower.

Mm-hmm. But to the twin that age slower, the other twin age faster. So what's the difference between the two? The difference is that one of them accelerated and the other one didn't. But they both accelerated relative to each other the same. Acceleration is not relative. Acceleration is absolute. They can both hold accelerometers and they can both tell which one is doing the acceleration.

They are not the same. Acceleration is absolute in the universe and velocity is relative. I see. Like by visual sight, they will both think they were both accelerating, but only one of them will really be accelerating. Yeah, if you're just measuring the relative distance between them, then you can't tell. But if you have an accelerometer, you can tell which one has had a force applied to them. I see.

It's a weird universe. All right. Well, I guess in the meantime, the best advice we can give is to just buy an air friar or a deep friar for your turkey. That will definitely cook it faster. Oh, I see. I thought by air fire you meant a friar which launches it up into the air, like high into the atmosphere where the gravity is less. Oh, there you go. So, yeah, and then bake it with cosmic rays.

So it'll be not just crispy, but also maybe mildly radioactive. Yeah. Look for that in the Daniel and Jorge merch store, the Sky Friar. That's right. Perfect for relatives. You don't like that much. Relatives, you want to fry with relativity. All right.

Well, I think that answers that question, which is that physicists are not quite sure if you can accelerate time. So far, we can only think of ways to slow. downtime. Yeah, very impractical ways to speed it up involving black holes and spaceships. Right, but even there, you'd have to like fill the universe with black holes except where you are. Yeah, that's an engineering problem. Right. Well, that's a big problem for everybody. I think if you did we would all suffer. Everyone at the Thanksgiving table. All right, well, thanks again to all of our listeners for sending in their questions. It's always fun to answer them here on the podcast and to see how curiosity works for everybody and what kinds of things people.

who are thinking about and wondering about. So engage your curiosity, ask questions about the universe. And if you get a good one, write it to us. Questions at Danielanhorpe.com. That's right. Call that lever that says, ask the question. All right, we hope you enjoyed that. Thanks for joining us.

See you next time. For more science and curiosity, come find us on social media where we answer questions and post videos. We're on Twitter, Discord, Insta, and now TikTok. Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio. For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their nuclear.

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