Daniel and Kelly’s Extraordinary Universe - What is the Cosmological Constant?

Episode Date: April 21, 2020

Was it Einstein's greatest blunder, or smartest prediction? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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On the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want or gone.

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Listen to the Good Stuff podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hey, Daniel, what happens if you have a great new physics theory? I mean, just really beautiful, gorgeous. perfect explains almost everything this sounds great so far but oh i knew there was a but coming but but it's wrong about one thing well is it like a little thing yeah just a little thing called the whole universe all right well is it like just a little bit wrong it's wrong by about the size of the whole universe doesn't sound like such a great theory but you know there's always a fix oh yeah what's that oh well engineers would love it we just add a fudge factor and yours have safety factors

not Fletch factors. But that's it, really? You just put a big number in it and you can fix it. Yeah, step one, put in a big number. Step two, give it a fancy sounding name. Hi, I'm Jorge. I'm a cartoonist and the creator of PhD comics. Hi, I'm Dan. Daniel Whiteson. I'm a particle of physicist, and I have never fixed a theory with a fudge factor.

Not yet, Daniel. How about a podcast? Have you fixed a podcast? I've never fudge the physics on this podcast. But I've also never come up with my own theory of the universe. Have you had fudge while you were recording this podcast? My theory is that fudge is the basic element of the universe because it brings joy. And in the end, what's life about other than beauty and joy? And chocolate, obviously. But welcome to our podcast. Daniel and Horhead. Explain the Universe, a production of iHeart Radio. In which we compare the universe to various snack foods, delicious and dark and dense sometimes. But with all the stuff that's happening out there in this crazy world, we want to take you on a tour of the grandest, deepest, most amazing, but yet strangely accessible questions of the universe. That's right.

We want to take your mind and have it go on a trip out into the far reaches of the cosmos and to think about what it is that we're all doing here. and how did this crazy universe come to be? And why is it the way it is? That's right, because the universe belongs to all of us. And wondering and being curious about the universe is as old as being human. And we think that everybody should understand

what scientists are thinking about what the deepest questions are and what scientists are pretty clueless about and only pretend to think they understand anything about it. Physicists are a bunch of things sometimes. That's right. And not little questions, and not by a little bit. Sometimes we need a really, really,

massive fudge factor. That's right, a really big bowl of fudge. Hey, you know, on a bad day that sometimes that's all that makes you feel better. That's pretty good about right now. Yeah, I wouldn't mind swimming in a swimming pool full of fudge. All right, we'll wipe that mental image, folks, and replace it with questions about the universe. So to the end of the program, we'll be talking about what such fudge fact about the universe that physicists have come up with, and this comes up a lot in discussions about the entire universe and the theories that underlied like general relativity and dark energy. That's right. And this is one of my favorite topics in physics because it's a topic where we are absolutely sure that we are in the beginning days of

understanding. Like if you go back and read in history about people thinking about the nature of reality and are things made out of atoms or made out of fire and water, it feels like, man, they had some pretty crazy ideas back then. They had no idea what they were doing, right? Yeah. Well, there are fields of physics where we are also just starting out having all sorts of crazy ideas, which physicists in 10, 50, or 100 years will look back and snortle at. Yeah, and this one's particularly interesting because it all sort of comes down to a number. Would you say it's the biggest number in physics? It's definitely the wrongest number in physics.

The wrongest and the biggest. Oh, man. One of the weird things about this number is why it's so small. Like, we think it should be a lot bigger, and it turns out to be kind of small, and we don't understand that. I see. It's a small number numerically, but I'm saying, like, in terms of significant, and it's a huge number. It's a little number with big significance.

It's the biggest slice of the fudge pie of the universe. So to the end of the program, we'll be talking about what is the cosmological constant? All right. So this was a question that was sent to us by someone from Belgium. So this is Pascal asking, what is the cosmological constant? Hi, Daniel and Hawke. I have a nagging question about the cosmological constant.

I understand that Einstein introduced the cosmological constant in the field equation because he thought that this would make the universe static. But in fact, the presence of the cosmological constant in the field equation actually shows that the universe is expanding. So that's why he said that this was the biggest mistake of his life, which by the way, shows one more time how brilliant he was. Even when he was making a mistake, it turns out that he was right. So my question is, how does the presence of the cosmological constant in the field?

field equations showed that the universe is expanding. And more deeply, where did this cosmological constant come from who, quote, unquote, invented it? Thank you so much for your podcast and cheers from Belgium. All right. Cheers, Pascal. Thanks for sending in that question. And I think it's awesome that it's a question that's nagging her. Is it a question that nags you also, Daniel? Does it keep you up at night? Oh my gosh. The history and future fate of the universe totally keeps me up at night. I mean, that's like the biggest question in physics, you know? Literally. Literally the biggest question in physics. Are we living in a space that's going to be crunched? Are we exploding out into the heat death of the universe? What is the shape, the size,

the nature, the dynamics of the universe? Like, thought of as a whole object. It's, it's incredible that humans can even consider things so vast in our tiny little minds, right? And sort of comes down to one number, almost. It seems to come down to one number, a number we had to insert into the equations to explain what we see. And you know, the reason I love this topic is because not only do we have fresh new ideas for how to explain what we see, but our understanding of what we've seeing has also changed. You know, a hundred years ago, we thought there was just one galaxy in the universe. And then we discovered there are other galaxies and they're zooming away from us. And then we discovered, oh my gosh, the things are expanding even faster and faster. So like,

only 20 years ago did we figure out that there was this weird thing called dark energy tearing our universe apart. And now we're struggling to explain it. So yeah, it's a big knack and question. Is dark energy just fudge? Maybe. Hmm. Something to think about. Fudge energy would have been a better name. There you go. Quantum fudge energy. The number is called the cosmological constant. And so as usual, we were wondering how many people out there know what this term means and where it came from. So as usual, Daniel went out and asked people on the street, what is the cosmological constant? And before you listen to these answers, think about it for a second.

And if someone asked you what it is, would you know what to say? Here's what people had to say. I have no idea what it is. The idea that there's one constant that explains all the others, so we don't have to have, like, 42 to explain all the different little stuff. I think so. I have no clue. Does that, I mean, it has something to do with light, maybe, I don't know, because that's a, yeah.

Cosmological constant, so I would say it's something to do with, like, creation of life or along those lines. Probably, like, a number. like the Uler's constant or something, some mathematical thing? It's some sort of scale factor, I guess, is the best way to describe it. No. If you had to guess, just fixed on the words. Like movement, something like that. Something that's more fixed and something that throughout time they've seen constantly there.

Heard of it, but I can't remember it right now. Okay. I believe that refers to Einstein's whoopsie in which he had to add a factor to an equation. to account for either the repulsion or attraction that would actually make the evolution of the universe's topology, I guess you might say, stable or not stable. I know I'm getting that way right. It's also synonymous these days with dark matter, I think, or the effect of dark matter. Totally.

I guess something to do with how the universe expands? Okay. Something about the shape of the cosmos? I'm not sure. All right. Some pretty good answers out there. Yeah, some people are pretty close. And then some other people sort of grasping at, you know, broad things. Because it sounds broad and consequential, right?

Cosmological. Yeah, it's not like the local neighborhood constant or my sofa, my sofa constant. It's like, it's going for the, it's going for the fences. Yes. Cosmological concept. Yeah, it's a dramatic name. What do you think about the name? You approve it? Well, let me see what it is, you know.

Is it cosmological and insignificance? I think you'll find that it is. My guess is that it's not even a constant then. Like, you guys got even that part of the name wrong. That's a good guess. And, you know, it's a kind of thing where you think it's a constant, you call it a constant, then you discover, oops, it's changing, and you still call it a constant. The only thing that's constant is the name.

Right, yeah. The only thing that isn't changing about it. But it is sort of a pretty big topic, and it all sort of, originated with Einstein, right? This is something Einstein came up with, kind of by accident? So tell us about the history. Yeah, this is something you have to understand the history of it. And Pascal's question really goes to that. You have to understand sort of where Einstein's mind was when he was trying to explain the universe. And you're right, it began with Einstein, but really was Einstein building on what Newton did. This was like in 1915 around, right?

Yeah, this is the early 1900s. And Einstein was trying to understand the universe and its shape and how gravity works because he had gotten these ideas from Newton that everybody else had that gravity is something where two objects with mass pull on each other and he didn't like this idea and he tried to come up with a more general idea

for what gravity might be and he reimagined gravity completely his idea of gravity was not that gravity is like a force where two objects pulling each other but that it's sort of the effect of mass on space itself right so space is no longer

just like a backdrop. It's not like an emptiness on which things happen. It's a dynamical part of the universe, meaning you put mass into space, space changes. And so he imagined gravity as a bending of space. Any local density of energy will bend space around it, changing the shape of the universe. Right. And this idea sort of came up from the equations, right? Like if you sort of look at the equations of gravity and things moving because of gravity, you can sort of look at the equations in two ways, as a force or as a kind of a bending of space. It's not like he suddenly came up with this idea. Well, I think it had a complex history, and it required him to merge some ideas and mathematics that had recently been developed. But I think it's a pretty big conceptual

shift to say gravity is not just a force between two objects like electromagnetism, but it's something conceptually very different. It's a changing of the shape of space itself. I think that's sort of mind bending the way. You know, the mind bending to think about space bending, right? And so he came up with this idea, and it worked really well for lots of things. He was able to recover Newton's theory from it. He showed that thinking about gravity in this way gave the same predictions that Newton gave, right? It didn't mean apples should fall differently from trees, right? Because Newton's theory sort of worked, right?

It's been tested a lot of ways, and it even explained the motion of the planets mostly. And so it's important when you come up with a deeper theory that it still explains all the stuff that Newton had gotten right. Right. In Einstein's theory, the apple doesn't fall from the tree. It just sort of rides down the space time or sits in the same space time divot. Yeah, it surfs, right? It surfs on space. But the motion is the same, right? Einstein doesn't predict that you'd see anything different from when an apple falls. But then it did make small differences in predictions for like how Mercury moved. Oh, really? Yeah, it's the procession of Mercury. And so he proved that his idea was right and that Newton's idea was wrong. But then he took the idea even bigger.

all right, if we think about this, what does that mean for the whole universe, right? Can I understand what that means for, like, everything? He also swung for the fences. Yeah, he went cosmological. He's like, hey, it predicts his apple. Let's go for the universe. And you only have to think about it for a moment to realize, well, if the sun bends space so the earth moves around it, right?

That means that mass and energy is bending space sort of towards itself, then what's going to happen when you have a lot of mass, like a universe-sized blob of mass? Well, it's going to cause things to contract, right? It's going to cause things to contract. What do you mean, like it under its own weight? Yeah, the gravity of all the stuff in the universe should pull all the stuff together, right? If you're Einstein, you think, okay, I have an empty universe, space is flat. Then I add galaxies and stars and gas and dust.

What should happen? Well, space will bend in a way to pull all that stuff eventually together. And so in Einstein's universe, originally, all that stuff should compact, should fall into itself, and eventually create, you know, like a huge black hole. But do you need Einstein's gravity formulation that way? Would a Newton also predict that everything would just pull on itself and collapse? Oh, yeah, that's a great question. Right now, in Newton's universe, you don't necessarily get a collapse.

I mean, you have gravity, and it's pulling stuff together. But in Newton's universe, space is flat. And so it's possible for stuff to be arranged in a way that's sort of stable and static, like the way that our planets orbit the sun and don't call it. collapse the way our galaxy doesn't collapse because it's spinning. And in Newton's time, remember, they only knew about our galaxy. They didn't know about other galaxies out there. So even this concept of the larger universe was not around.

But for Einstein, space can bend. And so even if things are in stable orbits like they are here, they would still eventually collapse. In fact, Einstein's calculations were done assuming that everything was smoothly distributed. So even in a universe where gravity would all cancel out like that, Even in that scenario, he predicted that everything would collapse. So in Newton's universe, things could be arranged stably so they don't collapse, where Einstein, without the cosmological constant, predicted everything would eventually collapse. But that's a problem, right?

This prediction, this consequence of his theory or consequence of gravity, that the universe should be, like, falling in on itself, is not what Einstein thought was happening at the time. Because back then, if you looked out into the sky, things looked pretty static, right? Nothing looks like it's crunching together. Yeah, back in 1915 or so, people thought the universe was static, that the stars were just hanging there in space,

and there was no relative motion, and things were just sort of fixed. They'd been that way forever, they would be that way forever. Things looked pretty peaceful. Yeah, and so when Einstein came up with this theory, and it predicted that the universe should be falling out in itself, he thought, uh-oh, there must be something wrong, right?

Something must be wrong with the universe, or with his equations? well he didn't doubt that the universe was static he tried to fudge his equations he says all right well if the universe is not collapsing it on itself then I need something to prevent it from collapsing something to push in the other direction to keep it static to balance it because if you apply

his theory to the universe or just really it doesn't have to be the universe right you had just any collection of mass back at least in the way that they thought space and mass was like back then then that's sort of inevitable right? If you have gravity, everything's going to come crunching down together. So he's like, wait, that's not happening. So therefore, I'm going to fudge my equation.

Yeah, he fudged it. He said, all right, so what I need is something to balance gravity. So he has this equation, which predicts the, basically the velocity, how things will move through space based on the matter and energy density. And he just added another number with a minus sign. To balance it out. To balance it out. To make it match the idea of a universe that's not collapsing. Yeah. He said, if there's some effect on gravity from mass and energy, what if there's something else which is pushing back, something else which provides a counterbalancing influence so that there is no overall gravity? And so this is his famous fudge factor, right? And did he call it the cosmological constant or was that name given to it afterwards? He called it the cosmological constant. He named it capital lambda and he chose this minus sign. And there's no explanation for it. It's not like it comes from any.

anything. It's not like there's a bottoms up physics reason why it should exist. It was really just added to try to describe the universe that he was seen. Interesting. All right. And so this number has been described as Einstein's biggest blunder. And so let's get into whether or not it was a blunder or not and what that means. But first, let's take a quick break. 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 glass. 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. My boyfriend's professor is way too friendly, and now I'm seriously suspicious.

Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. It's even more likely that they're cheating.

He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Your entire identity has been fabricated. Your beloved brother goes missing without a trace. You discover the depths of your mother's illness

the way it has echoed and reverberated throughout your life, impacting your very legacy. Hi, I'm Danny Shapiro. And these are just a few of the profound and powerful stories I'll be mining on our 12th season of Family Secrets. With over 37 million downloads, we continue to be moved and inspired by our guests and their courageous.

told stories. I can't wait to share 10 powerful new episodes with you, stories of tangled up identities, concealed truths, and the way in which family secrets almost always need to be told. I hope you'll join me and my extraordinary guests for this new season of Family Secrets. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, Daniel, did Einstein commit a blunder or not when he introduced the cosmological constant in his equations? What do you think?

I think it totally is a blunder because... Really? Yeah. Well, it didn't even really solve his problem. Like, the problem he had was that gravity was pulling in and he needed something to be sort of pushing out. But the way he described it was a very delicate balance. like he needed this number to be exactly the right thing

so that the effect of gravity from mass would be balanced by the effect of gravity from this weird cosmological constant. But it doesn't work unless they're exactly balanced. But I guess why do you call it a blunder? I mean, I would just think he's just being a good scientist and be like, oh, I need something. I'm trying to work with these equations

to make them fit what I'm observing. Therefore, I'm going to add this. It's not like he maybe thought something wrong, did he? No, but my complaint is that it doesn't even really work. Like, if you actually had a universe like that, then it wouldn't be static because any little extra pocket of mass that was over-dense, like, you know, a solar system or whatever, would start this runaway effect because it's not stable. Like, an extra pocket of mass very quickly generates extra gravity and overcomes this cosmological constant. And so while he wouldn't have, like, everything drawing into the center, there would be lots of little collapses. Oh, I see.

His theory doesn't even really predict a static universe. I see. You're saying putting it into the same equations that he had before made it balance, but it's like a super precarious balance. Yeah, and technically it only works if matters totally evenly distributed through the universe and there's no extra little spots of extra density. And if there are, then those very rapidly coalesce and collapse. But isn't that what happened with galaxies, aren't galaxies and planets really just like small concentrations of mass?

And so he's not describing what's happening, right? he's trying to describe what he thought was happening, which is a stable universe, but his description doesn't even lead to a stable universe. You mean the whole equation's wrong, not just that constant? Yeah, I don't think the equation is he put it together describes the static universe that he was trying to describe. All right, so how did they know it was a blunder?

Well, I think it's a blunder because it doesn't even describe the universe he thought he was describing, but then it turns out that the universe is different from what he thought, that the universe is not static, right? that the universe he was trying to describe suddenly shifted from under his feet. Right, because we now know that the universe is expanding, right? That's right.

Later on in the 1930s, they discovered that galaxies were actually moving apart from each other. That's right. Hubble, building on work of various other people, discovered that there are other galaxies out there, and they're really far away, and they're moving away from us faster and faster. So he discovered that the universe is not static,

that it's expanding. And so this sort of blew up Einstein's idea because he had worked carefully to add this number to his equations to describe a static universe, and then it turns out, oops, the universe, not actually static. Well, his problem was that he called it a constant, right? If he had called it not, or is it that even did that whole math equation is wrong? No, the problem is not that he called it a constant, that we can talk about later about whether we think it's varying in time.

The problem is that he put this number in to fudge his equation to describe a static universe, which is not our universe. Okay, so we don't live in a static universe, therefore any equation that assumes that is wrong. That's right. And so then Einstein abandoned the cosmological constant, and he never actually said it was his greatest blunder. But after that, he was definitely not a fan of it. He thought it was not well motivated, and you're sort of putting it in by hand, and it doesn't come from anything. It doesn't really make sense.

Oh, I see. Well, he was pretty cool about it then. He didn't try to hang on to it. And this part is a little bit confusing because you might think, Well, Einstein put the cosmological constant in to prevent the universe from collapsing in his model, but then he discovers the universe is expanding. How does he get rid of the cosmological constant, right?

Just put another number in it, a plus number. Well, the cosmological constant already was pushing in that direction, right? The cosmological constant he had kept the universe from collapsing. It was a positive, repulsive force, right? Can you just make that number bigger and it'll explain expansion? Right. And so down the road, in order to explain expansion and accelerating expansion, we're going to have to make that number bigger.

But what Einstein did was get rid of it, right? Not make it bigger, but he just made it zero. He's like, oh, this is wrong. And that seems confusing, right? Because then... He went the wrong way. There are two things to keep in mind here at once. The expansion, which is like a velocity.

And then the change in expansion, which is like an acceleration. Just like in your car, you have a certain velocity. And then the engine or brakes gives you acceleration to change of that velocity. Now, the cosmological constant is more like the engine. It gives acceleration to the expansion, either positive or negative. Now, Einstein had originally assumed that the expansion velocity was zero, that we lived in a static universe, and so he set the cosmological constant to zero to also give no acceleration. So what Hubble discovered is that the expansion velocity was positive. Hubble didn't measure the acceleration. He couldn't. So Einstein at that point knew that

his no expansion, no acceleration description was wrong. Now, when Einstein tossed out the cosmological constant, it gave him a universe with negative acceleration because gravity was collapsing it. But it could still have positive expansion velocity at that moment. Sort of like driving at high speeds at the same time as hitting the brakes to slow you down. So no cosmological constant means negative acceleration, which would eventually turn the universe's expansion around into a collapse. But Einstein was more giving up on the whole idea, using the cosmological constant to get balanced and get zero acceleration and zero velocity. So the cosmological constant tells you how fast the expansion is changing. Yeah.

Okay. And so by making it zero, then Einstein thought that he was saying, okay, it's expanding, but it's not accelerating. It's not getting faster and fast. Yeah. So Einstein's vision, I think, was the universe is expanding right now, but I'm going to get rid of the cosmological constant, which means that expansion. which means that expansion is decreasing. And so in the future, Einstein thought the expansion would slow down, stop, and eventually the universe would still collapse.

Boy. Can this Einstein guy get anything right? I mean, but he was kind of wrong about that too, right? Because later on, more recently, we discovered that the universe is expanding faster and faster and faster. That's right. Hubble was right. The universe is expanding. And the question was, is that expansion slowing down quickly or is that expansion slowing down slowly? And we went out to measure it.

it and discovered that neither of those are true, right? That the expansion is accelerating, that it's going faster and faster every year. Right, yeah. And we figured this out by watching supernovas explode, which has let us understand how far away things are, and how fast they're moving away from us, and we reconstructed this sort of history of the speed, the things are moving away from us. And that told us that things are moving away from us faster and faster every year. And so not only is Hubble Saw is the universe expanding, but that expansion.

is getting faster every year. Right. We've had podcast episodes about this, about the idea that the universe is kind of exploding. Yeah, the universe is sort of being torn apart. Yeah. It's going through puberty or something. The most precise way to think about it, I think,

is that space is expanding, right? We're creating new space between us and other galaxies. And a very common question from listeners is, if space is being created between us and other galaxies, why isn't it being created between us and the sun or between me and you, or between Jorge and his banana. And it is, it's just that we're getting pulled together by gravity. That's right, it is.

It's being created equally everywhere. That's why it's a cosmological constant. It's constant in space. Everywhere in space is being stretched the same way. But as you say, the Earth is holding you onto it, and the sun is holding us by its gravity, and our galaxy is holding itself together. Even like the air inside of your mouth right now is literally expanding.

It's literally expanding. Yeah. Everyone's brain is literally. exploding right now. Not just because of us. That's right. And we call this dark energy, right? It's just physics shorthand for we have no clue what's going on.

This is, you know, something we observe. We see that the universe is expanding. And this is something we only discovered, you know, 20, 25 years ago. It's mind-blowing to realize that before that we were ignorant of this really basic fact about our own existence. Right. Well, so I guess my question now is then, is dark energy related to the cosmological constant, you're sort of making it sound like it's made the same thing. Like what Einstein was missing in his equation was the idea of dark energy and that maybe this constant is related to it or is it totally separate?

It's related to it. And, you know, the idea is you see something out there in the universe, something you don't understand, which is like the universe is expanding and that expansion is accelerating. That's dark energy. Just the observation that the expansion is accelerating. No cosmological constant idea involved yet. there's several possible explanations for dark energy, one of which is the cosmological constant, right?

How do you describe it? You want physics equations that describe it so you can understand it, so you can predict it. So you need to somehow describe it. And so one way to describe that is to take Einstein's field equations, which are awesome, and put the cosmological constant back in. Back in. Put it back in.

He had taken it out, and now everyone is saying, no, no, wait, don't take it out. It actually helps us understand what's happening. That's right. And you need to put it back in and put it back in larger than he did, right? He put it back in to try to balance the universe on a knife's edge to keep it static. And then he pulled it out again. He's like, oh, the universe is not static.

I'll just let it collapse in the future. Now we've got to put it back in and crank it up so that it's accelerating the expansion of the universe. Everyone's like, more fudge. Put more fudge in. Don't put it in the fridge. Just pour the whole thing in. That's right. He put in some fudge.

Then he took the fudge out. and now we've doubled the fudge. Now it's double fudge. It's a double fudge universe. Maybe Einstein's blunder was just picking the wrong ice cream flavor. You never know. All right, let's get into whether or not this cosmological fudge constant is real and what that means for the fate of the universe.

But first, let's take a quick break. 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 glass. The injured were being loaded into ambulances. Just a chaotic, chaotic scene.

In its wake, a new kind of enemy emerge. 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. My boyfriend's professor is way too friendly, and now I'm seriously suspicious.

Oh, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy?

That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast.

I had this, like, overwhelming sensation that I had to call her right then. And I just hit call, said, you know, hey, I'm Jacob Schick, I'm the CEO of One Tribe Foundation, and I just wanted to call on and let her know there's a lot of people battling some of the very same things you're battling. And there is help out there. The Good Stuff Podcast, season two, takes a deep look into One Tribe Foundation, a non-profit fighting suicide in the veteran community. September is National Suicide Prevention Month, so join host Jacob and Ashley Schick as they bring you to the front lines of One Tribe's mission.

I was married to a combat army veteran, and he actually took his own life to suicide. One tribe saved my life twice. There's a lot of love that flows through this place, and it's sincere. Now it's a personal mission. I don't have to go to any more funerals, you know. I got blown up on a React mission. I ended up having amputation below the knee of my right leg and a traumatic brain injury because I landed on my head. Welcome to Season 2 of the Good Stuff.

Listen to the Good Stuff podcast on the Iheart Radio app, Apple Podcast, or wherever you get your podcast. All right, we're talking about the cosmological constant and we're talking about how it's something that Einstein put in, then took out and then people put back in because it explains how the universe can be expanding faster and faster. So it's kind of a real thing because we're seeing it. But Daniel explained to us what it actually is and physically what it means and how does it explain?

explain how the universe is expanding. Yeah, so nobody knows the answer to any of those questions. So we could just end the podcast. All right, well, then, thank you very much. We'll end the podcast right here. It's a fascinating question, and it's something physicists are thinking about a lot, and it's worth understanding what physicists do not yet understand. And the first thing to know is sort of the mechanics of it, like, how did he put it in?

Well, the equations for general relativity are very complicated, but you can solve them in some sort of simplifying assumptions, and you get like two equations, one that gives you the expansion in the universe, the other that gives you the acceleration. And if you look at those equations, you can Google them later. You see that there's a term there for mass and energy, and that has one effect. And he just literally put in a number with an opposite sign to balance it. And so it's something, Einstein's description of mathematically would be something, which has the opposite gravitational effect of mass and energy.

And you have to put it in a certain sort of solution of the equation. Yeah, you have to put it into the equations in a certain place. Because it's not in like E equals MC squared. That's not where it is. It's somewhere else in the equation. That's right. That E equals MC squared is not part of Einstein's field equations for general relativity. And so it goes into those field equations.

And this is what we do in physics. We're like, all right, this model, these equations describe what we see. Then what does that mean? The next step is interpretation. Like, why is it like this and not something else? What does that tell us about the universe that we need this number here? Okay. So people agree, he put it in the right place.

But they don't agree that it's actually a constant, is it? Well, we don't know. And the way you can interpret it sort of physically is to think about it like maybe it's the energy of empty space. Right? Because if space itself has some energy inherent in it, then it could have this effect. I see. Right. So we're like searching for a physical explanation.

And this could be totally wrong, right? This could be like, you know, maybe the universe is made out of air, fire, and water. It could be that level of idea, which in a hundred years people scoff at. But we're just groping around in the dark here. And this is what we came up with. What you came up with was that space is not space and emptiness is not emptiness. There's actually something not in empty space. Yeah, there's something in empty space.

And it's important that this gets something really big right. If you think of it as the energy of empty space, not as something in space, then as the universe expands, as space expands, you get more space. You get more of this stuff, right? because say you have like a cube of space and it has two hydrogen molecules in it and then it expands, right? Well, you still only have two hydrogen molecules in it. So the density of stuff in the universe has decreased.

So the gravitational effect of that stuff has decreased. But the cosmological constant, the energy of empty space, is constant. So you get twice as much space, you have twice of much of this mysterious dark energy. It kind of sounds like magic. Like you're like the, you know, like the total energy in the universe.

it just bubbles up from like an infinite fountain. Yeah, it's pretty weird. And gradually, it sort of takes over. Like, as the universe expands, you get more dark energy. And so the fraction of the energy of the universe that's in dark energy just grows and grows and grows and grows. And eventually, it's going to be totally dominant. Does that mean that the energy of the universe is not being concerned?

Well, that's a whole other question. It's a great question. It's pretty complicated. I think we should dive into that in a whole other podcast. But the brief answer is that the energy of the universe might just be zero. So where is all this new energy coming from? There's a lot of negative energy in the universe

that's bound up in gravitational interactions. And so this new energy can be balanced by negative energy of the gravitational interaction. That's, oh, I see. When you create something, oh, I see. Like if you're creating space between you and me, there's energy being created by the space, but we're also sort of storing it

in the gravitational potential energy between us? Yeah, there's negative energy in our gravitational potential because you need to add energy to free us. Like, if you have Daniel and Jorge orbiting each other, right, we're bound together gravitationally, then in order to make a free Daniel and a free Jorge, you need to add energy to the system. In order to pull it apart.

Yeah. So that means that that has negative energy. Weird. But it's weird that the universe kind of wants that. It wants to free you, Daniel. I don't know. Why didn't want you to come to me? I don't know.

I don't know why the universe wants what it wants. But it's weird to think about dark energy because it feels like a strange coincidence. Like we are living at a time when right now dark energy is about 70% of the universe. We know eventually it's going to take over. So why is it that we happen to live at this time when like matter is 30% and dark energy, matter and radiation and all that stuff is 30% and dark energy is 70%. It feels like sort of a weird balance. Really? Why? I mean, like if we were, if the human race had come up a billion years ago,

we might be asking the same question, like, oh, why is it 67% and 33%. But if you look at the history of the universe over a trillion years, only the very first blip is going to have any sort of balance between matter and dark energy. Most of it will be dominated by dark energy. Even before us? No, no, the dark energy is the future, not the past. Oh, I guess I mean like we're wondering why it is the way it is like that now, but if we had been born a billion years before, wouldn't it also be odd?

It would also be odd, yeah. It's weird to find two things in balance. that won't stay in balance, right? We don't think that there's anything that's keeping dark energy in balance with these other forces. Eventually, it will take over. And so it's just sort of weird

to be alive at a moment when it hasn't yet taken over because most of the history of the universe in the future, it will be in charge. But in the past, is it less or more? Less. Okay.

Less because, yeah, the universe is getting more and more dilute, and so dark energy is growing in importance. Oh, okay. All right. So these are all related to each other,

the cosmological constant, the energy of empty space and dark energy, are these all different names for the same thing? Or I guess help me understand why we have three names for it. Yeah, there's sort of three layers of ideas there, and there's one more layer we should get into. Oh, great. The dark energy is the description of the accelerating expansion in the universe.

That's like experimental. Something is out there doing this. We call it dark energy. The cosmological constant is an attempt to describe dark energy using gravity. Say, well, maybe it's just a feature of gravity, right? Oh, it could not be. It could be something totally different. We could not need a cosmological constant,

and there's something completely different going on. Oh, really? Oh, I see. I get it. All right. Yeah, yeah. There are other explanations for dark energy that don't involve the cosmological constant.

So the cosmological constant could still be zero, like Einstein said. It could still be zero, yeah. Oh, see, you guys were calling him a blunderer, and you don't even know. I'm going to switch over to T. Einstein here and say maybe, I'm going to keep with him. I think that's bananas. And the cosmological constant is an attempt to describe that, right?

And then we go, we say, well, how can we explain the cosmological constant? If it exists, if it's real, if it's there, what could be creating it? This energy of empty space is an attempt to calculate what the cosmological constant should be. Oh, I see. It's a theory, it's a hypothesis built on a hypothesis of a hypothesis. Yeah. And because maybe it would work. Like, if you then sat down and said, all right, what is the energy of empty space?

and can I calculate it? And if I get the right number, if I get the number that actually measuring out there in the universe, that suggests that I'm right. Okay. So they sat down and they said, all right, how much energy do we expect there to be in empty space? And you can calculate this

because we know that there are quantum fields out there in empty space, like the Higgs field, which is not at zero. When the Higgs field is at its lowest level, it's not at zero. And we talked about this in another podcast, what would happen if the Higgs field collapsed down to zero would destroy the universe. So we're lucky, we're happy that the Higgs field is not at zero.

But then if you add up all the energy you think is stored in the Higgs field and various other fields, you get a number. And you compare that number to the number that we measure for the cosmological constant. And they're different. Oh, I see. So this idea that there's energy everywhere is not unusual. You're saying that all of the quantum fields have energy in them. And you're saying that they actually have too much energy.

Yeah. The number you get is too big by a factor of 10 to the 120. Maybe Higgs is fudging it too, you know? Higgs-flavored fudge. I don't even know what that means. But could it be also maybe like a field that we don't know about? Is that possible too? Or like thinking like, you know, maybe these fields are leaking or something.

Yeah, exactly. People say, well, maybe there's another field out there we haven't discovered. And it happens to cancel all the other ones to give us a really tiny number. And that's weird, right? Like, it's weird if these two things balance each other to 120 decimal places to give us the number that we measure. Let's call it the fudge field. The fudge field. And so that's not very satisfying, right?

And then other people say, well, who cares about those other fields? It doesn't even have to be a field. It doesn't even have to be the energy of empty space. It can just be a basic number of the universe. Like maybe it's just a parameter of the universe. Like a remainder. Or just like the speed of light, you know, or the, Plank's constant.

You know, maybe there's just a number, and it's part of the universe. Like pie? Yeah, yeah, exactly. And people don't like that answer either because then, well, why this number and not any other number? And to answer that, you have to go multiverse, which is also unsatisfying. I feel like we're stacking crazy hypothetical ideas one on top of the other. How deep does this go, Daniel? This is about as deep as it goes.

Once you get to the anthropic principle and the multiverse, you really can't go deeper into the scientific baloney. I see. You've got to throw your hands up and be like, That's just the way it is, folks. Well, you're drowning in scientific bologna at that point. We're out of fudge. That's it. We filled the pool with fudge, and we're in the deep end now.

Well, what is this anthropic principle? I think it means that things are just the way they are, and we think it's weird only because we happen to exist. Yeah, it says when you have a random number, you can't explain. It says, well, maybe there's an infinite number of universes, and each one has a different random number, and only in the universes where that random number happens to be what it is so that you can have intelligent life.

Do you have intelligent life asking why is that number what it is? I see. There are other universes where this cosmological constant is different, but there's nobody around to ask the question. Yeah. If on those other universes, the cosmological constant was some crazy big number, and the universe just like exploded in the first bill a second

and no interesting structure formed, then you didn't get awesome podcasts asking about the nature of the universe. Or maybe there are universes where, you know, the two guys having a podcast that are wondering, I wonder why Pi is 7.6. They must live in a different geometrical space then.

Yeah. But, yeah, and I find that answer totally unsatisfying because it's kind of like saying there is no answer. Stop asking. There's nowhere deeper to go.

And that's not who I am. You know, I'm always going to be asking questions. I always want to dig deeper. I want to just want to know why. You're like, I'm sure Einstein was wrong. I know it. I'm pretty sure Einstein was wrong. I have to go on team, not Einstein.

Oh, I see, anti-Einstein. Oh, man. I mean, I'm pro Einstein in general, but in this one, I don't think you got it right. All right. Well, I think that clears it up a lot for me, how all these things are related. So let me try to recap then. So we know the universe is expanding, and we call that dark energy. We know the universe is expanding and its expansion is accelerating.

Right. It's getting faster and faster, and we don't know what it is in any of our equation. So we just call it dark energy. And so we have a theory about what that could be, and maybe it's due to gravity and so that's where the cosmological constant comes in and then we don't have a good explanation

for the cosmological constant so we just poured a lot of fudge in it and then call it, call it the energy of not energy. That's right, the fudge of empty space. All right, well I think it's pretty interesting though to think about these huge questions

about the universe, you know, and how, A, we don't know what's going on and B, how even people like Einstein and are sort of grasping at straws sometimes. That's right. And we made a little bit of fun of science here for having silly ideas. But, you know, this is how real science gets done. When you're on the forefront of human ignorance, you try crazy stuff.

And you say, well, maybe it's something like this. Can we make this work? Can we make that work? Because, you know, the universe is ridiculous. And so no ridiculous ideas should be discarded because it might be correct. It might be accurate. It might describe our ridiculous reality. Right.

This is the best we can do, folks. It's a process, right? If you want to join in the fun, go study physics. That's right. If you've ever done any writing, you know the rough draft is always pretty rough. And that's where we are now. All right. Well, thank you very much to Pascal for asking this question.

And we hope that helps you sleep a little bit better at night. That's right. And remember that the biggest questions in the universe about the biggest universe out there are still unsolved, which means you might be the person to figure them out. Thanks for joining us. See you next time. If you still have a question after listening to all these explanations, please drop us a line.

We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge, that's one word, or email us at Feedback at danielandhorpe.com. 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 new Christmas toys.

Then everything changed. There's been a bombing at the TW. UA terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. 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. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit.

Well, Dakota, luckily, it's back-to-school week on the OK Storytime podcast, so we'll find out Soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast and the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation about how to be a better you when you think about emotion regulation you're not going to choose an adaptive strategy which

is more effortful to use unless you think there's a good outcome avoidance is easier ignoring is easier denials easier complex problem solving takes effort listen to the psychology podcast on the iHeart radio app apple podcasts or wherever you get your podcasts this is an iHeart podcast