Daniel and Jorge Explain the UniverseDaniel and Jorge answer questions from listeners, like you!
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Hey Daniel, what's been in our inbox lately?
Well? We get the usual stuff. People with minor corrections, people with you know, cosmic questions, people asking me for to send them special stuff for Father's Day.
So he said, people were asking about Father's Day.
Yeah, some people write in I like this because they're not actually fans of our show, but their dad or their mom is a fan of the show, and they want us to send a special Father's Day or Mother's Day message to their parents who listens.
So it's like young, cool hit people saying, Hey, my dad likes your show and I have no ideas for any Father's Day gifts. So do we charge for these or we.
Don't charge for these because we're nice guys and we like helping people, and we're also fathers, and so I want to give a special shout out to Paul Truslow, who's daughter Caitlin asked us to give you a special Father's Day message. So Happy Father's Day, Paul and roll Tide, I'm supposed to say.
Also, Hi, I'm Jorge. I'm a cartoonist and the creator of PhD Comics.
Hi, I'm Daniel Whitson. I'm a particle physicist by day and a podcaster by any other time.
And welcome to our podcast Daniel and Jorge Explain a Universe, a production of iHeartRadio.
In which we really do, honestly try to answer questions about physics, questions that we have, questions that you have questions that we just randomly float into our minds some days.
Yeah, and if you actually send us a question, either at questions at Daniel Andhorge dot com or any one of our social media channels like Instagram or Twitter or Facebook, we will actually get to your question and maybe even talk about it on the podcast.
That's right, because when you have a question, probably other people have the same question. And that's the wonderful thing about having people suggest questions because sometimes there's an angle to something that we haven't thought of because we come at it from a scientific perspective, and seeing it from the point of view of the audience helps us really explain these things, really get down and untangle all those mysteries that you have in your mind, because our goal is at the end of this day you have a crystal clear picture of what's going on in this universe.
And if you send us a question that stumps Daniel, you actually get a prize, right, Daniel.
Yeah, banana cake. I know it's a podcast that has to be audio, so the sound of whoorgete eating a banana cake that Daniel made?
How about that some reader shows give you your phone message, they'll record your your voicemail message, we will record one of the hosts eating bananas. What could be better than that?
Yeah, well, hey, that could be a good ring tone, right, that could be a good ringtone. Hey, I got a call coming in. How do you know it sounds like something's eating in your pocket?
Yeah, that's right. If you're if you're the kind of person who doesn't like people believe we you voicemails, this is the contest for you right here.
That's right, that's right. No, Seriously, I would love to get a question that stumps me. I do get questions. A lot of times. I get questions I've never heard before, and that's a wonderful experience because you know, there's the standard of the questions people ask. But then there's a question I'd never even thought to ask before, and that's wonderful because it gives me a little view into the mind of the questioner. I have to think, what did they understand or what was going on in their head that inspired this question, so that I can then figure out how to guide them from there to a clear picture of what's actually happening. And that's the challenge of teaching, and that's what I really love about it.
So these are questions you hadn't even thought anyone could ask or would ask.
Yeah, I'll give you an example. I give demonstrations at elementary schools sometimes and we use like liquid nitrogen and all sorts of stuff to you know, one time we froze bananas and shattered it on the ground and the kids thought that was cool. And afterwards we're open for questions.
Wait, wait, wait, you shattered a bananas.
That's right, some bananas were harmed in the making of this podcast. I have to admit it.
Oh man, my heart is bleeding, Daniel.
But afterwards we were open for questions, and some kid raises his hand and he says, if lightsabers were real, would they be made of liquid nitrogen? And I thought, I have no idea how to answer that question. You know, like, where do you even begin.
You rolled your eye. You're like, obviously they're made out of kyper crystal. Wookid through your research.
I had not done my research on fictional universes and how science might work in that fictional universe. But I love that he connected two things he found amazing liquid nitrogen and lightsabers, and thought, maybe these are the same things. And actually we get a lot of emails like that. They're like, hey, today you guys talked about the mystery of you know, dark matter. Maybe that's the same thing as this other mystery. Like after our time episode, a lot of people wrote in and said, maybe dark energy is just a mistake on how we observe time, and time doesn't just move forward constantly. It's sort of stutter steps, and that's dark energy. People love to connect to mysteries and try to solve them at once. So you know that little boy in the class, he really exemplify the kinds of questions that listeners ask.
We're all just little Star Wars fans inside.
That's right, that's right.
Yeah, Well today we are answering your questions on the podcast. Today's episode is about listener questions Part four, right or are we up to part PI? Are we sort of this version? Pie?
I think our podcasts are integered numbered. Yeah, so this would be number four. It'd be awesome to have point one four of a podcast, but I'm not sure how do you pull that off?
All right, so today we have three interesting questions from listeners from all across the world, right, or at least the United States.
I think some of them are international. They don't always tell us where they come from, but based on the accent, I don't think all of these come from the Southwestern United States.
Which seems to be a big hotbed for fans of our show.
No, it was just random. Last time I happened to pick three questions which all like came from the south I was totally just random.
But today we have three pretty cool questions from listeners. One is about gravity, another one about dark matter, and the other one is about the nuclear of Adam, Like, how do they stay together? And why don't we all just explode into balls of nuclear explosions?
Maybe we will. You'll find out on today's episode.
I think people might already know the answer. But teaser, you're you're okay for the next couple of seconds.
You'll survive long enough to hear the end of this episode at the.
Very least, and then you can you can then explode if you like, from knowledge.
Do you think anybody has ever perished while listening to our episode? That just dark thought just entered my head.
Oh my god, let's cut that on.
Can you imagine being the last thing anybody ever heard in their life? Oh?
Wow? Right?
And making a joke about an inn.
Is it blew their mind stand that their idea of what a joke could be, and it just overwhelmed their neural network.
Yeah.
I don't know if that means the joke was amazing, so good that they couldn't take it, or they're just like, you know what, I'm done after that, I can't take anymore.
People get paid to say those kinds of jokes. Then I'm out of here. There's no reason to go on.
That's right, Goodbye, cool, unfunny world.
Well help. Neither of these things happened to you, my dear, our dear listeners. But our first question comes from Florence from Texas, and she has a question about how gravity could keep the Earth in orbit. Here's what you had to say.
I have a question about gravity. You've described it before as the weakest force, and you said in fact that it's so weak that when you're picking up an object with a magnet, you're overpowering the entire Earth's gravity.
So that's pretty weak.
My problem is when I start thinking about the objects and a Kuiper belt, there are thirty to fifty astronomical units away, and that's billions in billions of miles, and yet the Sun's gravity is still able to keep them in orbit. And that just gives me the impression that gravity is really strong, not weak. So those two thoughts really don't go together. Would you help me with that?
All right? Thank you, Florence from Texas. So that's a pretty interesting question, right, Daniel. Is that we often mentioned on the show that gravity is the weakest force, and it's actually super duper duper weak. But at the same time, I think maybe a lot of listeners are thinking, but wait, if gravity is a weak how is it keeping the Earth going around in orbit and other planets in Jupiter? And how is it such an amazing and incredible force in the universe.
It is an amazing, incredible force in the universe, And you're right to wonder about that, because as you look out into the night sky, you think about like all the structures in the universe, the Solar System, with the planets going around the Sun, and even the galaxy and the structures of galaxies and the superclusters, all of that is determined by gravity. Right, So gravity seems to have a huge, huge role in organizing the way the universe works, right, and the way we discovered dark matter was through gravity, and so if you just looked at it, you'd say, well, gravity is one of the most important forces because it shapes the whole universe. So then to hear somebody say, actually, gravity is the weakest force in the universe. That does seem like a strong contradiction, right, It doesn't make sense in your mind because how can it be the weakest force and also be the thing that shapes everything else?
Right, It's kind of like the organizing force in the universe. Right. It organizes planets into solar systems, and solar systems into galaxies and galaxies into clusters. Like if we didn't have gravity, everything would just fly fly away and fly apart.
Yeah, that's right. We wouldn't have any of the good stuff that we have without gravity. So we own a big thanks to gravity. And I like the way you said it's I sort of organize as things. I think that's one of the big ideas to understand how gravity can play such a big role and be so weak. It's sort of like the way you make a big mess in your house and then you come back home and your mom is organized the room or whatever. Right, some mysterious forces organized it while you were gone.
Your mum still cleansed your house. That's pretty good.
No, your mom cleans my house, or hey, she doesn't clean yours.
She flies from Panama every way every week and she doesn't even call me. Oh my god, maybe because that would celebrate Mother's Day.
Yeah, exactly, Well, you should have sent her a banana cake. No. But the point I wanted to make, the actual physics point, not a joke, is that gravity is a force that's sort of left over like all the other forces in the universe, electromagnetism, the strong force, the weak force. All these forces are so powerful that they get kind of naturally balanced. Like there's no electrostatic force or electromagnetic force between the Earth and the Sun. Why because if there were, it would be incredibly powerful and it would balance itself the way like lightning is a balancing of the electrons between the Earth and the sky. Right anytime there's any imbalance, shoom, there's a huge bolt of lightning to balance these things out. And so as a result, there is no electromagnetic force between these huge celestial objects, and so it's Gravity's gravity can't be balanced though, it's the one force that cannot be neutralized because it only has mass. There's no negative mass to balance it out. So after all the other forces have made their big mess, gravity is sort of left to pick up the pieces. It's the only thing left on the playing field.
Right, Well, I think it's important to maybe mention that when we say it's the weakest force, it's a relative assessment, right, Like, we're not saying gravity is weak, it's just weak relative to the electromagnetic force.
Oh I'm saying it. No, I'm saying gravity is super weak. It's embarrassing, it's puny, it's pathetic.
But only because you know other forces that are stronger. But if you didn't know the other forces, you'd be like, oh my god. Gravity is what keeps the Earth from going around the Sun, and the Earth is pretty big, so it's like a huge force. You just know that in comparison, it's kind of wimpy.
I guess. So, I mean, I think in comparison is really the only metric we have. It's also important to recognize how much weaker it is. Like if you took electrons, for example, and you asked, like, what is the force of their electrostatic repulsion compared to their gravitational attraction. Then the difference is like ten with thirty three zeros after it. So you know, millions, billions, trillions, quadrillions. You run out of numbers really quick. It's a huge difference. It's like a completely different scale.
Right, So you're saying, if I have an electron and maybe a proton, they're both being attracted by two forces, gravity and electromagnetism. But you're saying the electromagnetism is thirty two orders of magnitude stronger than the gravitational force between them.
Yeah, exactly, they're totally different scales, exactly. Electromagnetism, I mean, is a gagdillion. What's the word for thirty two zeros.
It's banana aliens.
You go, banana ca keazillion. It's so much bigger you don't even really want to describe them the same level. It's like, you know, the mass of the Earth versus the mass of a penny or something. You know, you don't call a penny a celestial object because it isn't right, so tiny, you just sort of round it up into the Earth. Anyway. The reason that gravity can still play on the field at all is that these other forces are so strong that they balance each other out, and gravity you can't do that, right, Like we were talking about one electron another electron, they repel each other, whereas an electron or proton they attract each other. Right, Gravity only makes attractive forces. Everything with mass feels gravity, and it attracts itself. There's no way to have repulsive gravity. We did a whole podcast episode about anti gravity. As far as we know, it's not possible. So there's no way to balance gravity out. After everybody else has done their stuff and been neutralized, gravity is left over, and so then it gets to organize the universe.
Yeah, I was thinking, like maybe an interesting picture is to imagine a proton in the Sun and then imagine a proton and an electric on Earth. It's not that there's no electromenetic force between that proton and this proton and electron. It's just that that the proton in the Sun, it's pulling the electron towards the Sun, but it's also pushing the proton away from the Sun with the exact same force. So our pair of proton and electron here on Earth just doesn't feel any electronetic force with that proton in the Sun, but it does feel gravity.
Yeah, exactly. And you know, there's lots of protons and electrons in the Sun and so they all work, they all arrange themselves in such a way that there's effectively no net force, and there's no way to arrange the protons and electrons to get no net gravitational force. There's just no way to do that.
But I think it's interesting to think about. It's not that there's no force, it's just that there's no net force. You know, like it is pushing and pulling as electromagnetically the Sun, but it all just sort of cancels out.
Yeah. Yeah, like it's pushing on a proton and is pushing on an electron in the opposite direction.
Right, But because our proton and the electron are holding on together, they're going anywhere.
Yeah, that's a fine way to think about it. And I think the other thing to recognize is that gravity is really really weak, but the Sun is really really big, like really really really really big, so it can have a pretty strong gravitational effect on the Earth even though gravity is weak because it just has so much mass, right, and so yeah, gravity is weak, but the Sun is so big that those two factors kind of cancel each other out and it becomes an important force.
Yeah, the weakness accumulates exactly.
You have like a billion people all whispering your name, it's going to add up to a huge scream, right, And that's the way it is with gravity. All those protons in the Sun are giving a tiny little tug on the protons and electrons on Earth gravitationally. But there's so many protons in the Sun that it's enough to pull a whole planet around in a circle. Right. It's not a small amount of force to keep the Earth in orbit. Right, it's a huge force that keeps the Earth in orbit.
Oh, man, you just gave me a new nightmare. To imagine a billion people bring my name. That is so bizarre.
That is kind of creepy. Actually know where that came from.
Hey, let's all whisper Paul's name for for Father's Day.
Do you think he'll sense a disturbance in the force when.
That happens, everybody listens to to this, right now, go Father's Day, Father's Day, your daughter's awesome? Cool? All right, that's Florence's question about gravity, And so the answer for Florence is that gravity is weak, but it's also happening on such a large scale that it does it is enough to pool planets and keep galaxies together.
That's right. And after all the other forces have done their business, gravity's left over to organize the universe because it can't be balanced out.
All right. Well that's one question and we'll get to the two other questions we have today about dark matter and atomic nuclei. But first let's take a quick break.
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Our second question of the day comes from Marging. We have a question about DarkMatter.
Hey, Daniel Njorge, this is Marchie.
My question is how does dark matter influence the movement of the planets in the Solar System.
Does it make them all orbit at the same speed, and if so, how all right, that's a pretty interesting question. We've talked a lot about dark matter in this podcast and how it's there. It's all around us, it's in the center of galaxies, right all over the galaxy, and it's constantly pulling on everything and helping galaxies stay together.
Yeah, this is a wonderful question because this is a kind of question that shows me that people are doing physics in their mind. Right. It says you've learned how dark matter influences how galaxies rotate, Like we discovered dark matter because we saw the galaxies were spinning too fast, so they need more gravity to hold them together. So that means that dark matter makes enough gravity to be like noticeable about how things spin. Right, So then the natural physics thing to do is to say, Okay, I have my new understanding, let me apply it to something else. Does that make sense? And this listener obviously thought, well, if there's dark matter enough to affect the galaxy spinning, why can't we notice it here on Earth? Like, why can't we do that same measurement and see like, hey, the Earth is going around the Sun too fast? Can't we detect the dark matter in our solar system by looking at how the Earth orbits the Sun the same way we look at how the Sun orbits the center of the galaxy. So it's really a genius question. Oh, I see.
The question is is the Earth going around the Sun faster than it should be if dark matter didn't exist?
Yeah, because imagine, for example, that there wasn't just the Sun in the center of the Solar system. Imagine there were five suns, but you can only see the one of them, right, and the other ones were made of dark matter? What would happen in that case? In that case, there'd be a much stronger gravitational force than you would expect from one Sun, and for the Earth to stay in its orbit, it would have to go much much faster, and so you would see a discrepancy. You'd measure the speed at which the Earth was orbiting the Sun, and you'd say, huh, it's going way too fast. What's keeping it together, keeping it in the Solar system? Why isn't it just flying off? And then you would deduce the presence of all those dark suns? Right, So this listener is like, well, can we see the dark matter because we've said on this podcast several times that dark matter is everywhere. It's not just out there, it's here, it's in this room, it's on your planet, it's hanging out in that bunch of bananas you just ate. It's everywhere. So why can't we see it in our solar system?
Right? Well, I guess question number one is is there dark matter in our solar system? And then question number two is is does it influence the orbit of planets? So Daniel's is there dark matter here in our solar system?
We think so. Now, we don't know one hundred percent for sure. The reason is that gravity is pretty weak, right, as we talked about recently, and so it's hard to get a sense for exactly where dark matter is because the only way that we can see it is through its gravitational effects, and so we can see its effects sort of like on a galaxy size scale, but it's really hard to get a very clear map of where the dark matter is. But we think it probably is. We think it's probably distributed pretty evenly through the galaxy. There's a blob in the very center and then sort of just falls off gradually.
So we suspect, like we would see it as a haze just permeating everything exactly.
And you know what a deep question about dark matter is, like is it just a smooth haze or are there structures? It's stuff happening. Is there like life forms in dark matter? We really don't know because we haven't been able to see it with enough resolution because the only way we've ever been able to probe it is through gravity. And that's a's, you know, real frustration for us as scientists. It's like most of the matter in the universe is there, it's right in front of us. We can't see it. We can't tell if it's doing anything interesting or just sort of a smooth haze, right, And.
So the question is if we are kind of in a bath of dark matter right now, which we could be or could not be. Maybe we're like in a bubble of non dark matter. Is that possible? We might be in a little gap.
It's possible, right, But I think the most sensible and the simplest assumption is just that dark matter is smooth, and as you say, we're in a bath of dark matter. I think that makes the most sense. It's it's the most likely explanation.
Okay, so in that case, if we are bathing in dark matter, would it affect the orbit of the planets.
So the short answer is yes, but not in a noticeable way. And the reason is that the Solar System is not big enough, right Like, if you take the density of dark matter, and we expect this is about like one proton's worth of dark matter about every three cubic centimeters, So there's not actually that much dark matter spread out over the universe, right.
Like, if you sort of look at your thumb, there's probably only one proton's worth of dark matter in it.
Yeah.
If you take all the dark matter and you spread it out evenly through space, then you end up with about one proton per thumb. I Like, the thumb is a unit of volume. Yeah, one dark matter proton per thumb. Thumbs up. Yeah, And you might and you might be thinking, hold on, isn't there supposed to be more dark matter than normal matter? And there is, but this five times as much. But here we're sort of spreading it evenly through space. So we can imagine how it might affect the Solar System.
But we actually don't sort of know that, right, Like, it could be all concentrated in my thumb, or it could just be kind of this haze it's covering everything.
Yes, it could all be concentrated in your thumb. No, there's some limits. I mean, if dark matter was really, really clumpy and it was all concentrated in your thumb, that would be a huge amount of mass and we would definitely notice that, Like your thumb would be attracting stuff to it all the time, like a crazy weird magnet.
My thumb is pretty attractive.
Well do you hitch hike lot? Does your thumb stop a lot of cars?
Uh? Yeah, No, get I get compliments for about my thumb all the time.
I don't believe that for a second. I don't believe that for a second.
You're like, I've seen your thumb. Hoory, it's nothing special.
Next time we're in a random situation, I'm gonna ask somebody to come in your thumb and we'll just see what they say.
All right, let's do it.
If you take one proton's worth of dark matter per thumb and you add that all up inside the solar system, it adds up to a lot. It's like ten to the ten kilograms of dark matter in the Solar system, and that might seem like, oh my gosh, that's a huge amount, ten to the ten, but it's small compared the Sun, which is like ten to the thirty kilograms. So dark matter, if you spread it out evenly, there is not enough of it in our solar system to influence the gravity on top of what the Sun is already doing.
So you're saying, like, our solar system is as kind of a concentrated part of the universe where there's a lot of mass here as opposed to like in the empty gas between solar systems, And so you're saying, like, here in our neighborhood, there is just a lot more of the regular stuff than there is dark matter. So dark matter is kind of negligible right here where we.
Are, exactly. Dark matter is negligible for the gravitational effects of the Earth and the Sun exactly right, because mostly the Sun is a concentrated blob of normal matter, and we don't think the dark matter has been concentrated in that same way.
Not only is it negligible, but it's also kind of spread out evenly all around us, right, So it wouldn't it would be sort of maybe tugging us in all directions at the same time, and maybe not really affecting the orbit.
It would be tugging us in all directions. But physics says that if you're moving in an orb bit, you're affected by the mass of all the stuff that's the smaller radius than your orbit, and actually it doesn't matter how that's distributed inside that radius. If it's like you know, like if the Sun was a point particle, or the Sun was its normal size or twice its size, if it doesn't change its mass, the physics says that it doesn't affect how the force of gravity acts on that body. It all integrates out to be the same thing.
So the dark matter outside of our orbit is just cannot affect our orbit.
That's right. It's sort of like that episode we talked about where you jump into the center of the Earth. You're only affected by the mass of the Earth has a smaller radius than you do. Everything else outside of you cancels out because there's always one bit tugging you here and another bit tugging you the other direction, and the stuff with a smaller orbit adds up to give you an overall tug. That's the same as if you just put a particle with the mass of that stuff at the center of mass of it, which would be the center of the Earth. So in this case you would still be affected by dark matter, and we are, like the orbit of the Earth is affected by the dark matter in the Soul system, but it's you know, one part in ten to the twenty, so it's not measurable.
So you're saying that we do sort of have like equivalent of a dark Sun in the middle of our solar system affecting our orbit is just very small.
That's right. Dark matter is changing our lives. It makes our years shorter by one part in ten to the twenty because it speeds up the Earth because of its additional gravity. But it's you know, it's not something we can measure on the galaxy scale, though you can, and the reason it affects things on the galaxy scale, the reason that you can detect it at all, is that galaxies are just so much bigger than solar systems, and so they add up to a huge amount of dark matter compared to the mass of the Sun.
Like the stuff in between solar systems adds up, but maybe the stuff within a solar system doesn't add up to much exactly.
So when you're calculating the force of gravity on the Sun as it rotates around the center of the galaxy, it's influenced by everything that has a radius smaller than its compared to the center of the galaxy, and that's a huge amount of dark matter.
Well, I think that's probably why I was late to the recording of this podcast. It it was, you know, dark matter shortening my ear.
That's right, Well, you used up your one you know, one ten to one intend of the twentieth of a year, so you need another excuse next time.
No, no, build over my entire life and leading out to me being late to this podcast.
It's not that you were finishing that one last piece of banana cream cake.
No, no, I finished that yesterday, all right. So that's Margie's question about whether dark matter affects the orbits of the planets in our Solar system, and the answer is yes, we kind of do have a dark matter sun in our or a dark dark matter mass in our solar system, making everything just a little bit faster, go faster around the Solar System.
But it's really not measurable, and without seeing how galaxy spin, I don't think we ever would have discovered dark matter just by looking at the orbit of the Earth.
All right, thank you, Margie, and so we'll get to our last question from Prida when we get back from a quick break.
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All right. Our last question of this episode comes from Prita, and she has a question about why the nucleus is stable. I imagine the nucleus of an atom, right.
What else could it be about the nucleus of what the cell?
The nucleus of a bananadam?
This is a physics podcast, man.
So here's a predest question.
My name is Pritto, and my question is why is the nucleus of an atom even stable? The nucleus of atom has protons which are positively charged. They're supposed to ripple each other and they're not supposed to stay to Please explain why does this happen?
All right? So Prito wants to know how a nucleus can be stable, like because the nuclei of atoms are made up of protons mostly right andle and neutrons but mostly but a lot of protons, and all the protons are positively charged, so they should be repelling each other with the electromagnetic force. Yeah, so how can they all stay together?
How?
How is it that you and I are here, Daniel?
Yeah, I love that we're talking about forces and force balancing and all these questions today. This is a great question, right, And they all are positive and they are pushing away from each other. So what holds it together?
I don't know.
That's a really positive thing, I think, yeah, and kind of negative too. Well.
I'm kind of neutral on the topic. But I was wondering whether people knew about this, Like is this a common question? Do people have an idea? So actually, yesterday when my kids were watching a movie, I walked aroun around the mall here at Irvine and I asked people if they knew what kept the nucleus together? And I got some interesting answers.
Cool, So here's what people had to say, Do.
You know why the nucleus stays together? Like? What keeps it together? If it's all positive charges, opposite force on the outside, or what holds an atom together?
Huh right, I'm sure I learned that in physics long ago, but I can't remember. I don't know about that one.
I don't know. More electrons they stay together because the more protons there are, the heavier the atomic weight.
So what do you think? Now we're getting random people in the street to answer listener questions. Eventually we don't even need to be here anymore, right.
Yeah, we should just crowdsource this podcast, go in the mall and be like, hey, here's the question. We'll give you twenty bucks to talk about it for forty minutes exactly.
That's our retirement plan. No, this one was interesting enough, and I really was curious about what people knew, So I thought, we don't often do this for listener questions. I bet I did the man in the street interview for this one.
Well, I'm surprised that people kind of knew a little bit of what you were talking about, right, because they were like, oh, you mean, like they open at them and they sort of understood the question because it's not an easy question to get your head around, right.
No, it's not an easy question. It's not a simple answer. But you're right. People understood the question and that was cool. So I think it is a common question. And all these people after I asked them, they're like, wait, tell me, what is the answer. You can't just walk away after asking me that question. I have to know. Now. It's like inspire this burning desire in them to understand why their nuclei were not flying apart.
Do you try to when you're roaming the malls looking for people? Do you try to always hit like the you know, the dad or the mom just waiting for their kids or their spouse who's shopping.
I try to ask people who are on their phone board. Yeah. I don't interrupt people in conversation or people who look like they're going somewhere. I look for somebody who's like sitting there on their phone obviously waiting for somebody to like try on pants or something, so they don't they don't. I don't want to interrupt somebody's day.
You go into the dressing room, you're like, hey, I have a BISIGS question for.
You, friendly neighborhood physicists.
Exactly physicists arrested at local mall.
And then I ask people in the next cell when I get arrested.
All right, So let's ask you the question. So, how is it that protons stick together inside the nuclei of atoms?
Yeah, Well, to answer this question, you need to understand a little bit about how protons and neutrons are held together. Because protons and neutrons, remember, are not fundamental particles, but they're made of quarks. So this upquarks and down quarks, and those particles are held together by a different force called the strong nuclear force. And it's called the strong nuclear force because it's super duper strong. It's much much stronger than electromagnetism, which of course puts gravity to shame. So the strong nuclear force is the strongest, most powerful force we've ever discovered.
That's what holds the protons together.
Yeah, it's the reason the protons and the neutrons they're bound states of this force. So there's quarks inside the proton and quarks inside the new neutron, and they're exchanging gluons all the time. There is this particle called a gluon, which holds the quarks together into a proton and into a neutron.
So that's what holds the protons and neutrons together. But what keeps the protons from repelling each other?
Yeah, so the strong nuclear force which holds them together. It's very short range, like it's super powerful, but it doesn't go very far, but it extends a little bit of ways past the edge of the proton. And so what happens is that there's a little bit of the strong nuclear force left over between the quarks inside the proton and neutron to attract the protons and neutrons to each other. So even this little extra bit of the strong nuclear force is enough to overcome the repulsion of the protons because they have the same charge.
Oh really, I never thought about that. Is that? How you explain it is that the force that's keeping the protons together is also the force that keeps a proton stuck to another proton because it sort of leaks outside of the proton.
Yeah. Essentially, it's like the quarks in one proton are talking a little bit with the quarks and the neighboring proton or the neighboring neutron, and to them. The fact that there's like an overall positive charge in protons and not in neutrons is irrelevant because those forces are so weak. Compared to the strong nuclear force.
The strong nuclear force doesn't care about your electromagnetic charge.
Right, yeah, exactly, it doesn't care at all. And the quarks do have electromagnetic charges, and actually they're really weird that like two thirds charges and minus one thirds charge. They're pretty strange. But the forces are much weaker than the strong nuclear force. So the strong nuclear force sort of leaks out of the proton and into the next neutron and into that next neutron, and that's how they tie themselves together. There's enough leftover after you make the proton or the neutron to tie it to the next one.
How can there be any leftover? I mean, if the proton is stable, right, like it likes being held together, how can it have any leftover? You know, attraction, doesn't it all just cancel out within the proton? How can you have some leftover to attract more protons?
No, you're right, and it would if all the quarks inside the proton were like right on top of each other. But they're not. They're like all sloshing around. So if you're like on one side of the proton, you're a little bit closer to one of the quarks. Than the other two, and so the force from that one little quark is enough to have like a little bit of leftover charge.
So actually maybe two protons being stuck together makes them weaker inside, right, each one is maybe just a little bit weaker because they're stuck to each other.
You can think of it sort of the way you know, atoms form molecules, right, and atom is electrically neutral, right, because the protons and the electrons right are balanced. But how do atoms form molecules? They're bonds between the electrons because the electrons, you know, they talk to each other and one like jumps from here to there, and they exchange photons and stuff. And so this is like protons getting stuck together by those extra little bits of leftover forces. So it's a strong nuclear force that's so much more powerful than an electromagnetism that even the little extra left of ribits can overpower the protons pushing away from each other.
This strikes me as little bit as a nuclear infidelity. You know, like you got three quarts being perfectly happy in a bond to make a proton, but then one of them is like, hey, look at that. There's some other quarts over there in that other trio me Naja troua protons. I'm a little bit attracted to them too, And so that's what brings the two things together, right.
Yeah, quarks feel a lot of love, right, They're happy to share their love with quarks even inside other protons and neutrons. And you know, there's sort of a limit how much you can do this because these forces are very short range, and so the bigger the nucleus gets, then the weaker the sort of the stability of the nucleus. If you're trying to make a nucleus that's too big, then like the protons on the opposite sides of the nucleus, they'll feel the electrostatic repulsion, but they won't be close enough to feel the strong nuclear force anymore. And that's why like heavier elements are less stable and more likely like decay radioactively. That's why we use uranium like uranium two thirty five to do radioactive fission and not like helium or lithium.
Put enough protons together, they bunch up and at some point the nuclear force, the strong force, isn't enough. They start to repel each.
Other exactly because the strong force drops very quickly with distance, right, And so if you're far enough away from the proton then you don't feel it. Then then it's like all the quarks are on top of each other. And so that's why there's like a maximum size you can make to a nucleus because the strong force which holds it together it's a very short range. And when the nucleus gets sort of bigger than that range, then it can't do the job anymore. It's like, you know, you try to hold a bunch of balloons, right, Imagine you trying to hold a huge pile of balloons as a maximum number you can hold until somebody you need somebody else to come over and grab a bunch of them. So then the nucleus splits into two, right, And that's what happens in a radioactive.
Decay, all right, So then that's the answer to the question. The nucleus stays together even though the protons are are repelling each other, they're trying to push each other apart. There is another force that leaks out from inside of each proton that then sort of links up the two protons together, and that force is stronger than the electromagnetic repulsion.
Exactly that's what holds them together, and that's what holds us together with you listeners, the force of these questions. You guys have all these questions bouncing around your head and you send them to us, and we love thinking about them, we love talking about them, and we love trying to explain them to you. And really it's this love of the universe and this desire to ask questions and this hunger to get the answers that brings us all together.
All right, Well, thank you so much to Florence, Margie and Prita for sending in their questions, and thanks to all of you who are sending us questions as well. We enjoy reading them and it kind of makes our day to hear.
From you guys. Absolutely, please don't stop sending questions questions at Danielandjorge dot com.
All right, and that's our podcas. We hope you enjoyed those questions, and stay tuned for more amazing facts and questions and interesting perspectives about the universe.
And stay tuned for the sound of Jorge enjoying a banana cake.
It's right, one of you lucky people will win this prize.
Lucky unlucky. We're not sure, but somebody's gonna win.
It, positive and negative. See you next time.
Before 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 Danielandhorge dot 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. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact. But the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. House US dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last Sustainability to learn more.
There are children, friends, and families walking riding on paths and roads every day. Remember they're real people with loved ones who need them to get home safely. Protect our cyclists and pedestrians because they're people too. Go safely, California From the California Office of Traffic Safety and caltrans.
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