Daniel and Kelly’s Extraordinary Universe - Classic episode - Why is gravity so weird?

Episode Date: September 5, 2024

Why is gravity so much weaker than the other forces?See 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 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 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. 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.

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I haven't auditioned in like over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We'll talk about all that's viral and trending with a little bit of chisement and a whole lot of laughs. And of course, the great Vibras you've come to expect. Listen to the new season of Dacus Come Again on the IHeartRadio app, Apple Podcast, or wherever

you get your podcast. I just think it's fascinating that it's such a fundamental force in the universe, right? Like, it's basically the thing that builds galaxies and keeps planets moving, right? It gives structure to the entire cosmos. That's right. On the largest scale, it's actually the most important force. It's the reason why things look the way they do. It's a reason why our planet is round.

It's the reason why we're on the planet, it's pretty important. And yet we don't know a lot about it, right? Like there's some really deep and strange mysteries about it. On one hand, we have a theory which works really, really well. On the other hand, we have questions about it, which seem really, really basic. And not only that, it's very different than all the other forces of nature. That's right. One of these things is not like the other ones.

Hi, I'm Jorge. I'm a cartoonist. And I'm Daniel. I'm a particle physicist. And this is our podcast, Daniel and Jorge, explain the universe. In which a cartoonist and a physicist try to figure out how to make the universe understandable to anybody. Yeah. And today on the podcast, we are examining a very heavy topic. Gravity. And specifically, why is gravity so weak?

And strange. Gravity, as we said earlier, is something which controls the structure of the universe. I mean, the reason the solar system looks the way it does is because of gravity. The reason the Earth is round is because of gravity. The reason we have galaxies is because of gravity. The reason we weigh so much is because of gravity, right? It's totally not my fault. No, that's because of late night cake eating.

But it's such a fundamental force of nature, right? Like it's present in our everyday life. We spend a lot of time thinking about gravity, right? How not to fall down, how not to drop things, how to go up buildings, how to go down buildings, right? That's right. It seems like one of the most important forces. I mean, if you ask people to name up, force or what kind of forces they experience in their life. Gravity is the one that's present in

their lives, right? You're climbing upstairs. You're fighting gravity. You trip, you fall down, you're feeling gravity. You look around you, the shape of things is controlled by gravity. And that's why it's particularly strange that gravity is the weakest force of all the forces we've discovered. It's by far the weakest. Yeah, it's really strange to hear you say that. Or like, how can gravity be weak? Like, you know, like it's keeping the whole earth together. It's making the entire planet swing around, go in a circle, basically, right? Without gravity, we would just shoot off into space.

That's right. It's a really strange situation. And there's other things about gravity we don't understand as well. It's really strange. It doesn't play well with the other forces. It's very, very weak. It's a total mystery to science,

except that we have a theory which works beautifully, right? We can calculate exactly how Mercury orbits the sun. We can send things into outer space and know with two millimeter precision exactly where they're going to land. We have a working. theory that we can use, right? But we don't understand it on a conceptual level. We have these

basic, deep questions about what gravity is and how the universe works because of it. So it's a weird question and maybe one that people hadn't thought about before. So Daniel went out as usual and asked people on the street, why do you think gravity is so weak? Here's what a random selection of folks who were willing to talk to me on a Tuesday morning had to say about gravity. I don't know. I actually don't know about that. I always thought was a pretty strong force. I don't know. But yeah.

Because it depends on the distance and it's a long-range one. So that's why we feel it very weak most of the time. Cool. No. Okay. I have no. I'm sorry. It's not very fruitful.

Hmm. I have no idea. But I'd be interested in finding out why. All right. That was pretty good. Most people weren't surprised when you said gravity's weak. I don't know. I feel like of all.

the questions I've asked people, this is the one that flummoxed them the most. People were like, what? I have no idea. They had crazy ideas why gravity must be weak. I feel like usually we get one person who knows what the answer is or has a good clue about what's going on. But this time, I feel like almost everybody was pretty clueless. I mean, one person said, I always thought gravity was pretty strong, right? Which kind of sums up the situation, right? Gravity is omnipresent in our lives, it dominates our experience, and yet it's so weak compared to the other really powerful forces we've discovered. Well, some people, a couple of answers were that it had to do with distance, like gravity

gets really weak with distance. That's right. And the problem there is that all the forces get weak with distance. Like electromagnetism also falls as the distance grows, right? So all of these forces follow this one over R squared rule, or R is your distance from the thing that's giving you the force. Right. Maybe, maybe, right?

Maybe, yeah, mostly we think. And so that can't be the answer, right? Because all the other forces have that same feature. So when you say it's the weak as it's not that it changes over distances differently than the other forces. That's right. So maybe we should talk about what the forces are and compare them to each other. So we focus and get an understanding of how crazy weak gravity is. All right.

So, Daniel, what are the forces of nature besides a bad movie with Ben Affleck and Sandra Bullock? Well, I think comedy. Comedy is definitely a force of nature. You know, it solves big problems around the world. No, the fundamental forces are electromagnetism, right? That's the one that controls electricity and magnetism, obviously, and is responsible for the cool things like light and lightning and all that cool stuff. And then there's the weak nuclear force,

which is a force which is responsible for radioactive decay of a nuclei, right? And the cool thing about electricity and magnetism, and the weak nuclear force is that we actually have shown that they're two sides of the same coin. As a particle physicist, we refer to them as one force. We call it the electro-week. So it's sort of magnetism lost out there in the name merger, right? It should be electromagnetic weak, but nobody voted to keep magnetism in the name of the partners on the law firm. Nobody lobbied for weak electro or?

Magneto-week force, yeah. Yeah, again, we are suffering. the fate of some anonymous committee of scientists they get to name these things, right? Who are these people? It's probably some grad student, right? Or some, you know, like this is really weird. We'll call it this. Yeah. So we have electricity and magnetism, which is a single force. We have the weak nuclear force, which is really, should be combined with electricity and magnetism.

And then there's the strong nuclear force. And this is the one that holds the nucleus together. You know, the nucleus is just a bunch of positively charged protons and neutral neutrons, right? So there's only positively charged particles in the nucleus. So you might think what even holds the nucleus together, right? You have all this positively charged stuff should be repelling themselves. Well, it's the strong nuclear force. And it does so by exchanging these crazy little particles we call gluons. And that holds the nucleus together.

And it's pretty strong. It's even stronger than electromagnetism. Well, let's take a step back. So in the universe, there's stuff. There's like stuff that exists. I can confirm that there is stuff in the universe. Yes, good. Without reservation.

there is stuff. I'm glad we saw that question. But I mean, it's like there's stuff that has substance to it, that has mass to it, or, you know, that it sort of exists. And then there's also besides that how these things interact with each other, like how they affect each other. That's right. There's the matter and then there's the forces, right? And the forces affect how they interact with each other. And that's pretty much the universe. That's like, it's matter and forces. Yeah, one way to look at the universe is that it's particles, right? Or you would say matter and their forces. In modern particle physics, we think about one level deeper,

which we think of quantum fields, and quantum fields are responsible both for matter and for forces. So we can talk about that maybe in another podcast. What is a quantum field? And how can I get one for lease or rent? What can they do for me? But yeah, I think it's fair still to think about

the universe in terms of particles and forces. On that note, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal, glass.

The injured were being loaded into ambulance. ambulance is 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. 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. Hello, it's Honey German. And my podcast, Grasas Come Again, is back. This season, we're going even deeper into the world of music and entertainment with raw and honest conversations with some of your favorite Latin artists and celebrities.

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Listen to therapy for black girls on the IHeartRadio app, Apple Podcasts, or wherever you get your podcast. There are only four kinds of forces. Yeah, there are four kinds of forces. So electromagnetism, weak nuclear force, strong nuclear force, and then, of course, gravity, right? That's the fourth force that we've discovered. Okay.

The fascinating thing is that different particles feel different forces, right? Like some particles feel this set of forces, some particles feel those set of forces, for example, right? Particles with electric charge feel electromagnetism, right? The electron, for example, is negatively charged. The proton is positively charged. You bring them close together, they're going to pull on each other. They're going to suck each other together, right? Because they have opposite charges.

We all know that. But you bring a neutral particle nearby. It just totally ignores it, right? doesn't feel it at all. Right. It's like somebody's walking through a crowd of people shouting, but they have headphones on, so they can't hear anything. They're totally oblivious to it.

It's kind of like how we talked about in a previous podcast. They're almost like languages or like social media platforms. Like some people are on Twitter, some people are on Facebook, but some people are not on this. And so if you're not on Twitter and somebody sends you a tweet, you're not going to get it. And so it's just different ways that particles interact. That's right.

Gravity is the Google Plus of social media, right? Because nobody uses it. The frenster. The frenster. It's ancient but powerless. Yeah, and so different particles feel different forces. And for example, an electron, while it feels electromagneticism because it has a negative charge, it doesn't feel a strong force at all.

They'll pass right by a bunch of particles that are really tugging on each other with a strong force and not be affected at all. Whereas quarks, corks feel all the forces. They feel a strong force, which is how they get pulled together in the nucleus. protons and neutrons are made of quarks. Quarks feel electromagnetism because they have electric charge. They feel the weak force. They also feel gravity, of course, because

they have mass. So quarks get their fingers in everything. They get the feels for everything. They feel everything. That's right. They got the strong feels. They're really deeply emotional part of the thing. And on the other side of the spectrum, you got things like neutrinos. The neutrinos don't have

electric charge, so they ignore all electricity and magnetism, right? They don't interact with light. They're invisible. They pass right through anything that they ignore electromagnetic bonds. They pass through most materials. They don't feel the strong force. The only way they interact is with the weak force.

And the weak force is pretty weak, which is why neutrinos can mostly just pass through matter unaffected. So we have four fundamental forces, right? And gravity is one of these forces. And so when you say that gravity is weak, you actually mean it's weak compared. to these other three forces. That's right.

And so the ranking is the strong force is the strongest. So that one is actually well-named. Congratulations. For now, right? You know, anonymous group of scientists. Yeah. Yeah, we should be called the,

as of 2018, currently known to be the strongest force force. Right. After that comes electromagnetism. And, you know, we know that force. It's pretty powerful. You stick your finger in a socket. You're going to feel the wrath of electromagnetism, right?

It's not an unfamiliar feeling, right? Try to stick your finger in anything you feel right? Because it's electromagneticism is the force that keeps you from basically passing through the table or passing through your car, right? That's right, because electromagnetism is the basis of chemical bonds, right? And chemical bonds are really the thing that form the structure of your body, right? You think of your body is like a bunch of particles, but it's held together by all these forces. It's like a chain link fence binding together these little particles and prevents you from passing through something

else. Yeah, so we got the strong force and then electromagnetism and then actually the weak nuclear force, right? This is the force that powers neutrinos and radioactive decay. It's much weaker than electromagnetism and much weaker than the strong force. Even weaker than the weak is gravity. That's right. If you make a list like strong force, electromagneticism, the weak force, then you should leave like

a hundred blank pages and then you get to gravity. Because when we compare these forces, we put things like at equal distance. apart and we compare the strength of the forces. Gravity is 10 to the 36 times weaker than the weak force. But that's 10 with 36 zeros in front of it. But isn't that sort of a matter of units or scale? Do you know what I mean? Like it's much weaker, but only if you compare apples to apples, right? Or oranges to oranges. That's right. But put two protons next to each other, right? Two protons have a certain amount of mass and a certain amount of electric charge. And the force of their charges is going to be

much, much stronger than the force from their masses. Oh, I see. So, yeah, if everything was much, much more massive, then there would be stronger gravity. But you can compare these things apples to apples by comparing them at the same distance and the same basic unit of interaction. Right, but what if you take an apple, put it next to another apple?

Well, I think you can do that experiment. Nothing's going to happen because gravity is so weak, right? You don't see two apples like pulling themselves together on the counter, right? There's no built-in apple collider. You know, the apples are not drawn to each other, gravity is a super weak force. And you can see this yourself, right? You can do an experiment where you counter the entire gravitational force of an enormous celestial body like the Earth,

right? Take a small kitchen magnet and use it to hold up a nail and think about what's happening there. You have the nails being pulled down by every single rock in the earth. It's pulling with all of its gravity, but a tiny little kitchen magnet totally overcomes that. It can lift the even though it's pulling it's being pulled down by the whole entire planet earth right exactly now imagine a magnet the size of the earth right i mean that would be that would be extraordinarily powerful and so you have basically like a gravitational blob the size of the earth still pretty ineffective compared to electromagnetism so so it's weak if you sort of compare it by object like you said if you take a proton put it next to a proton the the force you're going to

feel from electron magnetism is so much bigger than the force of gravity they're going to feel towards each other. The same with like two electrons or two quarks and things. So in the scale of like the particles that we know, it's a really weak force. That's right. Exactly. And yet, and yet it seems to dominate, right? That's a bit of a puzzle. Like on one hand, it's super duper weak and we're telling you that it hardly counts for anything. On the other hand, it's responsible for the structure of the solar system and for the galaxy. And it's the reason the universe looks the way. it is, right? Right. And so that can be confusing to people. Like, how do you reconcile those two things

in your head? Yeah. Like, why doesn't the earth feel an electromagnetic force with the sun, which would be so much bigger than the force of gravity? Yeah, well, it would be pretty shocking. And that's actually the reason, is gravity is different from the other forces in that it can't be cancelled

out, right? If there was some huge electrostatic difference between the sun and the earth, like a bunch of positive charges there and a bunch of negative charges here, it would create such an enormous force that it would be very quickly balanced. That's what lightning is, right? When there's a charge differential between clouds and the ground, it doesn't take that much

before those charges want to rearrange themselves to a lower energy configuration. They rush down to the ground or they rush up to the clouds or they jump from cloud to cloud to balance themselves out because you have two kinds of charges. You have positive and you have negative. So you can find an arrangement where basically everybody's happy. It's an equilibrium, right? but that's not true for gravity. Okay, I get it.

So, for example, if the Earth was, every particle on Earth had a positive electromagnetic charge and every particle in the sun had a negative electromagnetic charge, there would be a humongous pull from electromagnetism pulling the Earth into the sun. Yeah, we'd be toast pretty quick. Yeah, right? That would not be a very long-lived experiment.

Yeah, it would be huge. Even the opposite. If we were all positive and the sun was all positive, if we would get shot out of the solar system very quickly. That's right. And that's why early days of the solar system being formed, you have these gases and gas and dust coalescing, and very rapidly things neutralize, right?

Because anything that feels an electrostatic force to something else is going to find the opposite charge and they're going to coalesce and they're going to make something neutral, right? That's why most of the things around you are neutral, right? Most of the elements are neutral because any deviation from neutral results in a power force to neutralize it. So thankfully the earth is made out of both like equal amounts of positive and negative particles, right? That's right. Thankfully, we're sort of balanced electromagnetically. And so even if the sun was all positive, we would look like neutral, like a neutral ball to the sun.

Yeah, that's right. We're on large scales, the earth is neutral, right? I mean, there might be some residual positive or negative charge depending on the solar wind, et cetera. But basically the earth is neutral. And so the largest force of the earth feels is the gravity from the sun, even though gravity is super duper weak, right? It doesn't take a lot to counteract gravity, but it's the only player left because everybody else is sort of pare it up and danced off for the night. And gravity's just there left holding the bag. And gravity can't be balanced, right? You feel gravity if you have any mass, right? But it's only positive masses. There's no such thing as a negative mass to give anti-gravity. Wow. Well, let's keep going. But first,

let's take a quick break. Okay, so that's how gravity is so much weaker than the other forces. So how is it different than the other three forces of nature? There's like no end to ways that gravity is weird. You know, there's no end to like the puzzles of gravity. It's fascinating. pit. That's right. It's a black hole of questions. And one of my favorites is just that we have no way to sort of fit gravity in with the way the universe works according to everything else. You know, we talked

earlier about how we have particles and we have forces or quantum fields equivalently. And that's a really successful way to describe the universe. You know, we have the large hajohn collider to explore these things really high energies and we've understood all sorts of things using this theory. But that theory is uses quantum mechanics. So the way we describe interactions, you know, the way we talk about two electrons repelling each other or the way lightning is formed or anything involves passing quantum particles back and forth. And that's just not true for gravity. What does that mean passing particles back and forth? Like when, like if I have two magnets and they're attracted to each other, they're not, it's not like an invisible telekinesis pulling on each other. They're actually

swapping particles and I can't see that. that kind of what you mean? That's exactly what I mean, that the way two things interact via some force is by exchanging particles. And so, for example, electromagnetism, right, is the force behind a magnet. And the way electromagnetism works, we think at a sort of microscopic particle level is that there's a particle that transmits that force, that sends sort of the information back and forth between two things that are feeling it. And in the case of electromagnetism, that particle is the photon, right? The particle is also a packet of light. So each of the quantum forces that we talked about before,

electromagnetism, the weak force, and the strong force, each of them have a particle we associate with it. And that's not just like some name tag we put on and say, hey, you get this one, you get this one. We think that that's the particle that's responsible for making the force work. So when two electrons come near each other, how do they repel each other? How does that actually happen?

Well, we think that they send photons out, right? the electric field of a moving electron, an accelerating electron generates photons, and those photons interact with the other electrons. And so basically the passing messages back and forth using these quantum particles. So gravity is weird because we don't know that there is a quantum particle being exchanged

when two things get attracted gravitationally. That's right. So we have this great framework. We say, oh, maybe all forces are quantum mechanical fields, interacting with each other, right? Let's apply that to the electromagnetic field. Yeah, it works.

Let's apply that to the weak force. Yeah, it works. Let's apply that to the strong force. Ooh, cool, it works. Maybe this is something deep about the way the universe works. Let's apply it to gravity. Uh-oh, it doesn't work. Right?

So what does that mean? What does it mean when it says it doesn't work? Well, for a theory to work, it has to provide predictions for experiments. You have to be able to say, okay, theory, what would happen in this configuration? If I shot a proton and another particle, predict what would happen. And then you can go off and do the experiments and compare it, right? Well, when you do that for gravity, you try to form a quantum theory of gravity. It doesn't work.

You get nonsense answers. You get answers like infinity, right? Or things disappear. Or it just doesn't mathematically function. Like there's no way to build a theory of gravity that we've discovered so far that works. That actually explains the way these things happen. there are a few candidates out there they're pretty far from being a functional

theory of quantum gravity things like loop quantum gravity or string theory but the basic problem is that quantum mechanics and general relativity which is our best theory of gravity do not play well together we have no functioning quantum theory of gravity so does that mean that we don't have the right theory

or is that gravity is just not quantum in nature that's exactly the question we don't know the answer to right in a hundred hundred years from now, somebody will know the answer that, I hope. And they'll look back and they'll wonder, you know, oh, why do those guys see the clues? But we don't know. It could be that there is a quantum theory of gravity. We're just not smart enough to think it up yet, right?

Like the right person hasn't been born yet to put the math together. Or maybe it requires a different kind of math that we're using, right? There's some assumption we're making that's a mistake. Or maybe we're just giving it a wrong name. Like maybe it should be gravitunis or. Gravitinos. Gravitinos. Gravititas.

way that's taken. Exactly. That's definitely the problem. That's step number one. We made a mistake in step number one when we could define the particle. The other option, of course, is that maybe gravity is not a quantum force

the way the other forces are, right? The other forces, we call them quantum forces because they're well described by quantum mechanics. But gravity is kind of different. I mean, the current theory we have a gravity, general relativity, it doesn't like to describe gravity as a force. It describes gravity instead as a bending of space.

It says that when you have mass somewhere in space, space no longer becomes straight, becomes bent. Right. So the things move in curves and circles. And it's not like an actual, just a mathematical nuance or a mathematical perspective. What really confirms it is the idea that gravity can affect things that don't have mass, right? That's how we know it's more than just a force between things that have mass. It actually, like, affects space for things that don't have mass, right?

That's exactly right. So if you shoot a photon through space that has mass nearby, the photon will not move in what we consider to be a straight line, right? It'll find a path through this bent space that involves basically curving. And this is what Einstein predicted with his theory, and they saw it. You know, and you can see in space, it's called gravitational lensing. You can see photons get bent by heavy objects. And it's because, as you say, the heavy objects are bending space itself. Right.

It's not like gravity is pulling the photon because the photon, doesn't have any mass, right? That's right. The photon doesn't have any mass, yeah. So that's how it's different. Gravity seems to affect things that don't have sort of its fundamental property, you know?

Like, electromagnetic forces can affect something that does not have an electric charge. But gravity can affect everything else, right? Yeah, that's a pretty deep insight there. Not bad for a cartoonist. Not bad at all, yeah. That's a fascinating way to think about it.

I think that's totally correct. Yeah, and so if gravity is instead of being a force, if it's a way we change the shape of space itself, then maybe that's why we don't have a quantum theory of it, right? And that's amazing, and it's fantastic, and it's exciting. And another reason why we have a hard time bringing these two things together is that quantum mechanics, the theory we've developed, only works so far in flat space.

That is, if there's really heavy stuff nearby, we don't know how to do those quantum calculations. We can basically only do quantum mechanics in places where there isn't really strong gravity. So wait, so quantum physics doesn't work in reality, basically. Is that what you're saying? Like, it doesn't work in the space that we actually live in. Well, it works basically everywhere except for close to black holes. Right?

You need basically a black hole to have enough gravity to break down quantum mechanics. Because it's when space gets really distorted that you start to see the effects of gravity on space and then it becomes comparable to the strength of other stuff and that's when that's when quantum mechanics breaks down yeah quantum field theory works basically what we call flat space whereas gravity bends space wow so earlier when we categorize gravity as part of these four fundamental forces maybe that's just the wrong approach maybe you know do you know what I mean like maybe um we shouldn't be categorizing these four things as as one category of quote, forces, unquote.

That's right. It could be that there is no quantum theory of gravity as a fundamental force because it isn't one. And it's just a feature of space, right? Absolutely, that's one possible explanation. But then we still need a way to make quantum mechanics work in bent space, right? And we still need

to understand how to make our theory of general relativity play well with quantum mechanics. Because we think quantum mechanics describes the universe, right? And general relativity is not a quantized theory. It's, it's continuous. It treats space and everything as if it's infinitely divisible, right? It's not a quantum theory at all. In fact, it came about before quantum mechanics was even invented. And so while

the basic tenets of it, how it distorts space are probably correct. I mean, it's been verified to zillion degrees of accuracy. It doesn't feel like it can be a fundamental description of nature because it's not quantum mechanical. So like we want to call it a force because it seems to move things like all the other forces, but maybe it's not a force. Maybe it's just kind of like some other weird property of space. Yeah, exactly. Maybe we've been trying to put a round peg into a square hole all these years. A gravity peg in a quantum hole. That's right. That's right. And there are other ways that people are trying to solve this problem. Like one way is thinking that maybe gravity is a fundamental force, but it just works a little bit differently from the other

forces. For example, people think about how the universe might have additional spatial dimensions. Instead of just being able to move in three directions, maybe there's like four or five, six dimensions that you can move in. And folks who are interested in that should listen to our podcast on extra dimensions. No, yeah, we did a whole episode on extra dimensions, but we didn't sort of get into this particular topic. So tell us how extra dimensions might explain why gravity is so weak. Yeah, the idea is that maybe gravity isn't so weak. Maybe gravity is just as strong as all the other forces. But if there's a whole other set of dimensions out there, that is ways, directions that thing can move, it might be that gravity is the only thing that

feels those dimensions, right? It might be that those dimensions are invisible to electromagnetism and to the weak force and to the strong force, but visible to gravity. And what that means is that gravity might be basically leaking out into those other dimensions. You know, we talked about how the farther away you get from something, the weak of the force is. So like, Like, Mercury feels the force of the sun's gravity much more strongly than Pluto does, right? Irrelevant of whether or not you call it a planet, it doesn't feel gravity very strongly. And that's because it's further from the sun, right? I mean, that goes like 1 over R squared, or R is the distance.

It's one over R squared because we have three dimensions. If we had six dimensions, it would be one over R5, right? Which falls much more rapidly. So if there are additional dimensions out there, okay, and only gravity feels them, That might be the reason why gravitational force falls so quickly. Maybe gravity is actually just as strong as everything else when you get really, really close, but then these extra dimensions exist, and most of gravity leaks out into those other dimensions. Sort of like between you and me, there's not just the three dimensions between you and me.

Maybe there are other secret hidden spaces kind of between you and me, or these other dimensions. Exactly. Other ways for gravity to spread out, right? And so gravity would be like just as strong as all the other forces, but it's just flexing its muscles in these other spaces that we can't see or feel. Exactly. It's like, you know, if somebody's at the center of a crowd and they let go a really stinky fart, right? The people next to them, they smell it strongly.

And the people further away, they smell it much more weakly. And people outside don't smell it at all. Okay. Yeah. We jump into farts really suddenly, but let's go with it. Hey, I'm trying to make this accessible, you know. This is something everybody can appreciate it. You're trying to make win.

I get it, cut it. But if there was somewhere else for that fart to go, if it could move not just sideways, but also it could float up, right? Say you had a really tall room and the fart floated up, then people wouldn't feel it as much because most of the far would dissipate into the upper corners of the room. And so gravity might be the same way. It might be that, you know, for the first millimeter or so, the first centimeter or so,

gravity gets very weak, very quickly. It falls off really rapidly. and that then at normal distances like a meter or 10 meters or whatever you don't feel those other dimensions anymore because other dimensions only activate at really, really short distances. This is the theory people came up with

and we don't know if it's real, you know, we've tested it. So far it seems like gravity works the same way for galactic scales and for Earth scales and for microscopic scales. It seems to always fall off at the same rate as a function of distance. So nobody's ever seen any evidence of these extra dimensions. But it's a

fascinating theory and it's a, you know, It's one that would give kind of a natural explanation for why gravity would fall off so quickly and why gravity is so weak. It wouldn't explain all these other things. In fact, people sort of try to use gravity to see if there are other dimensions, right? Yeah, that's right. It would be a really cool clue, right? And that's a fascinating way that science is done. You know, you try to look at everything around you and see if you can fit it all into one framework.

Like, can I use this one set of ideas to describe everything? Right. Can I merge everything into one set of concepts? Yeah. That's right. Yeah, my fart theory of the universe. The best possible way I think to unravel this is to actually go visit a black hole because quantum mechanics and general relativity tell you very different things about what's happening inside a black hole, right?

As we said before, general relativity tells you it's an infinitesimal dot of almost infinite density. Quantum mechanic says, you know, the universe is quantized, first of all, so you can't have infinitesimal. dots. And also there's sort of a minimum size to stuff, right? And you can't have all that stuff compressed in such a tiny little area. And so if you could see inside a black hole, you would learn a lot about gravity. So what would be the plan? You would go into a black hole. You would observe and discover how the universe works, and then you'd be stuck there. That's right. They would have to send you a Nobel Prize into the black hole after you. Just assume you'd figure it out and toss it in there. The Nobel Prize into space, into the black hole. Congratulations.

anybody who's listening please do not go into a black hole please please do not go into a black hole but you know we don't need to visit black holes we could try to create them here on earth that sounds like a great idea yeah doesn't that sound like a great idea i mean wow i'm excited make a black hole on earth so sell me sell me yeah let's create a black hole and study it right um if gravity gets really really powerful when you get to really short distances because of this extra dimension theory then it might be that if you shoot two protons together really really hard and they get really, really close to each other, that you can create a super-duper mini,

extra cute little fuzzy black hole, right? I'm trying to make it sound like a cozy thing, not a dangerous thing. Yeah, you're trying to sell it. Sell it merchandising right. And so before we turned on the Large Hedron Collide about 10 years ago, people thought maybe by smashing these protons together, we could actually create black holes and we could study them, and we could reveal the deep secrets of gravity, right?

So then the idea would be to try to make them at the Large Hadron Collider and just kind of see what happens. Like does it tell us something about gravity or quantum physics at the same time? Yeah, exactly. By seeing how often they're made and how strong they are and what they turn into, when they decay. We could understand something about the way black holes work. And that would have been really powerful. But unfortunately, or fortunately, depending on how you feel about black holes, we haven't made any black holes at the Large Hadron Collider that we've discovered.

That you've, but maybe, isn't it true that maybe you've made them, but they evaporate? Yes, these black holes would be very short-lived. But, you know, everything we make at the Large Hadron Collider is really short-lived. These things last for like 10 to the negative 30 seconds or 10 to the negative 23 seconds. We're pretty good at seeing short-lived stuff because it usually blows up into other things. And a black hole would have a really unusual signature in our detectors. It would be pretty clear to see if we had made them. Okay.

But short of going into a black hole or detecting farts in extra dimensions, we, may not know in the near future what makes gravity so different. That's right. It's going to take some work. I mean, the other direction is theoretical is to build up a theory of quantum gravity sort of from the bottom up. Like start from the beauty of math and physics and then try to build it up to our level. Exactly. And that's a wonderful way to do is to say like maybe the universe works in this way, this most basic fundamental nature, and build it up from there and see if you can describe the universe that we see around us.

Oh. All right. Well, that's pretty shocking to think gravity plays such a big role in our lives. And yet it's like the weakling in the universe, right? It's like imagine if gravity was stronger. Life would be a lot more chaotic, right? And crazy. Yeah, exactly. We would be closer to the sun and everything would feel more intense. It's fascinating to me that gravity has been a mystery to physics for hundreds of years. I mean, it was the focus of Isaac Newton's studies, you know, like hundreds of years ago people working on gravity. And still today, even though we've made so much progress in terms of gravity, we still have so many basic questions about it that we don't know the answers to, not even the really beginning of how to answer them. To me, that's fascinating. Gravity is such a rich source of mystery for physics and for everybody.

Wow. All right. Cool. I think it's maybe time to push down this question. Thanks for joining us. 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. Ah, come on, why is this taking so long? This thing is ancient. Still using yesterday's tech, upgrade to the ThinkPad X1 Carbon, ultra-light, ultra-powerful, and built for serious productivity, with Intel core ultra-processors, blazing speed, and AI-powered performance.

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Hi, it's Honey German, and I'm back with season two of my podcast. Grasias, come again. We got you when it comes to the latest in music and entertainment with interviews with some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition. I haven't auditioned in like over 25 years. Oh, wow.

That's a real G-talk right there. Oh, yeah. We'll talk about all that's viral and trending with a little bit of cheesement and a whole lot of laughs. And of course, the great bevras you've come to expect. Listen to the new season of Grasias Come Again on the IHeart Radio app, Apple Podcast, or wherever you You get your podcast.

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