Daniel and Jorge Explain the UniverseListener Questions 46: Mountains, ether and time!
Daniel and Jorge answer questions about reviving old theories, building tall mountains, and passing time.
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Terms apply. Hey or hey. How are the mountains in Panama?
They are wet and hot and beautiful.
Wet and hot in the best possible way.
That's right, the safest for work sounds plasma.
Are they like tall mountains? Is Panama famous for having tall mountains?
Uh?
Sort of.
We're a pretty small country, but there is a pretty large volcano there.
It's about twelve thousand 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.
And do they have mountains there?
You know? They think they have mountains. But the highest point in Denmark is like five hundred feet above sea level.
But the rest of the country is like two thousand 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 Himmelbierg, which literally means the mountain of Heaven.
WHOA, how big is it?
It's like five hundred feet above sea level.
I think the hill I live on is bigger than five hundred feet. Does I mean I live in heaven?
You live in Danish heaven?
I live in California Heaven Valhalla. I am Horhem, big cartoonists 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 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 then 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 open 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 ten year in University of California to 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 iHeartRadio.
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 if 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 the green biology, not as for physics.
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 is like the direction of up and down, not the person living inside the sun pulling a lever.
No, you'd need one lever for every planet, right, How do you rise over Jupiter and set 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. 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 physicist and wonder how does that work work? 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 I do like mountains in the winter, that's when you can ski and snowboard.
You see that, like those are good things. I don't understand.
Yeah, they'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 four or five every day around here.
Well, there you go. Should just take the four or five 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 inside. We answer all of our listener emails. Please send your questions to questions at Danielanjorge dot com.
So today on the podcast, we'll be tackling listener questions number forty six, 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 the podcast?
Oh?
Are we doing that kind of podcast today? 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.
Scotch that's right. How do I know you're not the alien?
Hmmm? Or I could be my brother shimone. You know that my mother can't tell us apart on the phone still after fifty years.
Oh boy, 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 answer 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 be come on Earth before phystics limits it. When the base of the mountain grow larger and larger, does the curvature of the 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 countess Vikings? I think I've been there, and I think I did see a Viking ship there right, Yes.
The Danes, the Swedes, and the Norwegians 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 cleaned that up on our podcast Scandinavian Culture and History.
And those countries all speak very similar languages, like if you speak Danish, you can understand nor Region. If you speak Swedish, you can understand Norwegian. If you speak Swedish you can understand Norgi. Norwegians 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 there no limit to how big a mountain can be or is there a point of which the mountain just can 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.
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 and 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.
Hmmm.
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 and 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, tho, 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.
M hm 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 is 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 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 float 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 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, 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 granite? For example, if you had the gravitational force of the Earth, and the answer you get is about twenty two kilometers high, which you know, for a physics model is pretty good, like it's order of magnitude the right answer.
Interesting.
I mean, you plugged in the numbers and you got twenty two kilometers, But what does your model say happens after twenty two kilometers.
After twenty two kilometers, then as you add rocks on top, the bottom breaks down and it spreads out. So it basically max is out at twenty two 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.
Yet, yeah, you get a fat or mountain exactly.
But this 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 forests 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 slimming into the Asian plate and creating the Himalayas m 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 all 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 a love rocks, it starts to sink into the earth.
That's true. But here you have two plates pushing on top of each other, so one plate 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 or me.
That's the biggest factor though, right.
Yeah, that's the overwhelming factor to within their arabars. And that means that if you've wanted a taller mountain, you need, like India, to zoom faster along the surface of the Earth before it's 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 that 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 me and we can never model all the processes that control these things, so we try to just isolate, like 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 were 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 twenty two kilometers is the tallest mountain you could make on Earth without the base of it flowing out from under you. And as you say, they're also buoyancy effects, so I would guess somewhere around that number, around twenty 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 pulvarized 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 twenty you're seeing out of about twenty two kilometers, the more rocks I if we're into the more, it's just going to flow to.
The sides, mm hmm, yeah, exactly.
And then and then what's going to happen is the Earth gonna end up kind of ovalong 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 and radius by more than twenty kilometers.
All right, Well, I guess that's the general answer for Nicholas Daniels says that Quartantio's model, the biggest mountain that you can get on Earth would be about twenty two kilometers above sea level.
But that's a simple physics model. It ignores lots of stuff, So before you submit a pitch to the US 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.
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All right, we're answering listener questions here today, and our next question comes from Martin.
Back in the seventeenth and eighteenth century, it was believed that there was an atha that which permeated the universe. Business, of course, has now been disproved. However, fast forward, many years, and scientists have shown that there is a Higgs both on field. Although not exactly the same, they do seem to be quite similar. My question is, are 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 if 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 work 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, ooh, well, that sounds like the ether revisited. Ha ha ha, we know how all that worked out.
Oh boy, I didn't know if this is since 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 build quantum theory, which sort of relies on an idea that's very similar to either right quantum field.
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 Michaelson Morally 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 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.
M I wonder if you're sort of getting up to our 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 physicists 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 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 quark 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're sort of it seems like you make fun of people who believed in the ether, but at the same time, now you believe that there is something you 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, 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 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, need 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's 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 the 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 Fune factor, a cosmo logical 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 he didn't need it? Like, what was his mistake?
Well, he was trying to describe a static universe, the 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. 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, There was 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 it without it.
Yeah, if the universe is expanding, then without that fudge factor, you have two options. Either will 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 constante. 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 two thousand 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 factor to return?
And is that the official name of it, Einstein's fudge factor?
Eff No, the much fancier name of the cosmological constant. But the cosmological cost 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 concept might be from the quantum fields that fill space give an answer that are off by ten to the one hundred. So we're nowhere near understanding why this constant has its number M.
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 talked about on the podcast. But originally, in like the fifties and sixties, people were trying to use string theory to describe the strong interaction, but it didn't really work very well. And in nineteen seventy three, when we discover the Jape side 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 an string theory total failure. Couldn't explain the strong interactions. And then about fifteen 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 eighties and nineties, 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 they's 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 dust bin of theories.
All right.
Sounds like physics is constantly changing, right, And things that ideas that we thought were working, we would start out to work, and things we thought work.
Some things don't work. It's a process.
It's definitely a process, and we're constantly mining the past. If you look at the history physics, there are lots of scenarios where like nothing happens for forty 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 to 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?
Pa sh Ion.
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, But first let's take another quick break.
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Right.
We're answering listener questions, and our second question was whether there are a lot of concepts in physics that we thought weren't true but then we realize we're 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, don hold, I'm looking for a place in the universe. Will time go way faster? Related to the outo envelopment of this place, is there a place like that? What can make this place. Really, I thought maybe some gravitational a different speeds effect can cause it. What did you say? Thank you here? Nadav from Israel?
All right, interesting question.
I'm not one hundred percent 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 may be referring to is that, you know, a lot of the ideas we have about time is that they're about slowing down time, right, Like if you go close to the speed of light or really fast and 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 will do the opposite, that make time go faster.
Yeah, it'll go faster for the people like in the box. Right, So that people step in the box, they're in the box for a year in our time and out and one hundred years is past 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.
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 an a dove, though I think it's probably impractical.
Hmmm, Well, in practicality has never stop 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 they.
Used 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 one hundred million years.
Yeah, there you go.
If you want to like warn jeans, but you didn't want to wait and be fashion, well with a pH you could use this machine.
Yeah, Or you could roast to 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 then one of them is based on gravity and a 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 porges in a spaceship, he's flying by the earth. He is a clock. I'm watching his clock from the Earth comparing it to my clock, and I see Hojey's clock is ticking slower. So Horay's time is passing slower than mine.
Right, It's going slow for everybody, which is weird.
Yeah, because it's symmetric. You might think, well, if Daniel is seeing Jorges 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, that 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'd 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've 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 paradogs, which is like, if you take two twins and you send one of them to the next star system, going at almost as spituit 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 down the spaceship, accelerates, turns around, comes back will be younger than the twin that stayed on Earth.
So like, yeah, so like if you want 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 stick everybody else in the 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 acceleration, while velocity is totally relative. 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 states 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. And in case where they're just passing each other in space, they both see the other one's time as 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. 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 is, 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 space ship and have it come back.
That's a little bit logistically hard mm hmm.
And it connects nicely with the other time dilation because, as we've talked about in 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. And 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 to 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 it's time can move faster while it's cooking.
Right, Right, But I guess what I'm saying is you don't need it the black hole. You could 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. 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 times 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 is 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 into the sky, although you won't get that much of 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 want it to just age faster than everybody on 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 strength. So we don't really understand what time is. So if I said absolutely not, then in fifty years somebody would be like, haha, 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 and they laugh at each other over hot cocoa.
It's terror, right, They're like that Daniel 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, m I send the twin out into space, they come back they have H slower. But to the twin that H slower, the other twin h 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 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.
Mmmm.
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 fryer or a deep fryer for your quirky That will definitely cook it faster.
Oh I see, I thought by air fiument a fryer which launches it up into the air like hind of the atmosphere where the gravity is less.
Oh there you go.
Yeah, and then bake it with baked with cosmic rays so it'll be not just crispy, but also maybe mildly radioactive.
Yeah, look for that. In the Daniel L. 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 down time.
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. 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 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 Daniel and Jorge dot com.
That's right, call that lever, that's 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, to org, Instant 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.
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When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact, but the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. House US dairy tackling greenhouse gases. Many farms use anaerobic digesters to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last Sustainability to learn more.
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