Daniel and Jorge Explain the UniverseListener Questions 44: Deep questions from listeners like you!
Daniel and Jorge wrestle with the Earth's tilt, steampunk atoms and fundamental pixels of rad.
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Hey Daniel, are you happy with quantum mechanics?
You mean, like, do I understand it well enough?
Well?
I said, nobody understood it. But I guess I'm asking if you think it was a good idea, you know, like, if you were designing the universe, would you have made it quantum mechanical?
Oh that's hilarious. I mean, I'm pretty happy with our universe and all of its weird, glorious beauty. I hate to give that up.
But wouldn't be cooler if it made more sense? You know, if like electrons were really kind of little also stuff instead of fuzzy on certain random things.
It might be easier, but it might also be less interesting.
I don't know. I wonder if people would find it more interesting if it was easier to understand.
We might have more particle physicists in that case. Would that be good or bad?
No? No, No, you had have fewer, right, because it'd be easier to understand. You could be doing something.
Else, like hosting a podcast.
There you go, a real job. Hi am Jorgemy, a cartoonist and the author of Oliver's Great Big Universe.
Hi. I'm Daniel, and I'm a professor at UC Irvine and a particle physicist. But it's been a long time since I had a real job.
Or really, they've all been imaginary.
I think my last real job was working in the kitchen at McDonald's.
I see, what did you consider both jobs to be kind of the same. You're making hamburgers, You're making physics theories. It's all very high in calories, a lot of additives.
One of them is brain food. The other one's got food.
It's sort of food, right.
There's a little more creativity involved in one of these jobs than the other one.
MM, which one.
I'll leave that as an exercise to the listener.
Well, at least you did the experiment. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of iHeartRadio, A.
Grand experiment to see if we can explain everything in the universe to you. All the stuff that we understand about how things work at the smallest scale, to everything we don't understand about the little bits and the big bits and everything in between about the universe. This joyous adventure, the exploration of everything we do and do not know, we think should be shared by everybody out there, everybody who has that curious itch to understand the nature of the universe, to zoom forward to the forefront of human knowledge and understand what we do and do not know.
The tread because it is an amazing universe full of fast foods, slow foods, medium speed foods, all kinds of foods, food for thought, food for your belly, food for your soul as well. Do you consider physics to be soul food? Perhaps?
I think it nourishes philosophy, which is definitely soul food. You know, all the big questions and physics in the end have philosophical implications. Physics tells you, oh, the universes this way, and philosophy wonders, well, why and why isn't it that other way? And what does it mean anyway?
Well, sounds like we need to have an episode about the physics of the soul. Perhaps it'll be very soulful.
I think a lot of what we call the soul is the spirit of humanity, and that's where our curiosity comes from our desire to understand our context, why we live, to motivate the choices we make. I think a lot of that can be informed by physics and what it reveals about the nature of the universe we live in.
Wow. Nice, that's a great McDonald's answer. You spun that around really fast.
Would you like fries with that?
Yes, it is a pretty amazing universe out there, full of mysterious things and things that we've learned and things that we have yet to learn and figure out. And it all starts with having questions about all of these things.
And you can ask questions that are big, huge, Thanksgiving meal sized, or you can ask little questions, little snacks see individual French fries kinds of questions. We encourage you to ask all of them, and we're here on the podcast to try to help you answer them. All of our episodes are designed to scratch a piece of curiosity inside your mind. But it's not possible to cover every possible thing anybody could imagine, and so we want you to write to us with more questions the things that you wonder about the nature of the universe.
That's right, because everyone can have questions about the universe. You can be a professor of physics, you can be a philosopher. You can even be someone who works in the fast food industry, or maybe someone with a real job, like being a podcast host. Anyone can have questions about the universe.
Yeah, or you can be a combination professor, philosopher, podcast hosts, and McDonald's fry cook.
That's right, But accept a cartoonists. Cartoonists know all the answers already.
And I'm terrified to ask you. Is being a cartoonist a real job.
No, it's not a real job. Getting paid to have fun and doodle things. I don't know. I don't know if that counts as real. It's certainly a dream come true.
It's a scam, folks. You heard it here on the podcast.
No, No, I mean it's a dream. Oh I see the dream come true.
I think Ponzi had some dreams. Also, didn't he.
Bonse had dreams of getting other people's money. I just have dreams of drawing for fun.
Well, I think a lot of people out there dream about understanding the universe and getting their questions answered, having that experience when things click into place and you go, oh yeah, now I get it. So if you have questions about the nature of the universe, for example, how you could get paid to be a cartoonist or a physics professor, then please write to us two questions at Danielandjorge dot com.
Mmm, has this become a career advice podcast? That might actually make this more of a real job.
I think both of us have very odd and unusual career paths.
Yes, I don't think anybody went to our advice in terms of to make money or not make money, I guess.
But I do hope that people will write to us with their questions.
Yeah, and so today on the podcast, we'll be tackling listener questions number forty four. This is our forty fourth episode answering listener questions Daniel. Is there a theme to these questions?
The themes of these questions is that they come after the forty third episode and before the forty fifth episode.
Mmm. Does that make it like a special like numerical magical number?
These questions all came in within the same week, and I thought, ooh, these are interesting questions, and so we're going to answer them today. That's the theme I see.
The theme is that Daniel was too lazy to find questions with a real theme. Oh, it's all chronological, you mean, like all this time we've been answering questions chronologically as they come in.
I mean it's rough. Chronologically. I try to answer people's questions within a reasonable time frame. You know. They send me the questions that go on the list, we record the episode, it gets edited. It can be a few months between asking the question and getting the answer, so I try to shorten that. But then I also try sometimes to group the questions by theme when possible, but it's not always possible.
I guess it's more like a true representative sample of how we get the questions right.
Yeah, we are core sampling our listener's brains today.
Metaphorically, philosophically, in a cartoony kind.
Of way, auditorially.
Well, we have three great questions here today from our listeners. One of them is about the weather and the tilt of our planet, dealing one is about the structure of the atom, and the last one is about the fundamental nature of reality itself.
And radical angles.
Oh, we have radicalized questions, right, Well, let's jump into our first question. The first one comes from Chris, Hi.
Daniel and Jorge. What would weather be like on Earth if we rotate it around a horizontal axis rather than the readly vertical access we rotate around. Also, how would that weather differ if our axis pointed either towards the Sun or in line with our orbital path. Thanks for the great podcast.
All right, awesome question, although I'm confused, Like, is there a horizontal and vertical in space?
Well, there's horizontal and vertical relative to the Sun, right. The Sun sort of defines the axis of the Solar system. It spins around that has a north and a south pole of that spin, and then most of the planet's orbit in a plane that's perpendicular to that axis, and so the Earth tilts relative to that plane of the Sun.
WHOA, But are they I wonder if they're exactly the same, Like the axis of spin of the Sun is the same as the axis of spin of the whole Solar system, Like, exactly the same or has it changed a little bit?
Yeah, these are great questions. It's not exactly the same. Like some of the planets do not orbit in that plane, right, or they orbit a little bit off from it. It's the complex system with lots of things tugging on it. So it becomes chaotic. As other stars come nearby, they give little tugs to Jupiter andto Saturn. All these things accumulate over millions of years so that everything is not perfectly aligned.
Okay, So then if the axis of rotation of the Sun is the perfect vehicle, it's say, in our solar system, the Earth is sort of aligned to that, but not exactly right.
Yeah, the Earth's angle is tilted relative to the angle of the Sun by what seems like kind of a big number. It's like twenty two to twenty three degrees, where you know, ninety degrees would be totally tilted over and zero degrees would be perfectly aligned with the Sun. I was sort of surprised to look that number up. It seems kind of big.
Yeah, it seems like a lot.
It seems like a lot, And it's the reason why southern California is such a wonderful place to live, because we don't have winters. Winters are the direct cause of the Earth's axis being tilted.
Wait, what do you mean if we didn't have the axis tilted, we wouldn't have winter, or we would have winter.
If we didn't have an axial tilt. If the Earth rotated along exactly the same axis as the Sun. Then parts of the Earth wouldn't get more or less sun during different parts of the year.
Doesn't our orbit sort of just closer and a little farther from the Sun anyways.
Yes, there's also that effect that you get a little bit closer and a little bit further. Most of the reason we have seasons is because the axial tilt.
So if we didn't have the tilt, we wouldn't have seasons.
Yeah, we wouldn't have seasons, or we'd have much much milder seasons. It would be due to smaller effects like the eccentricity of the Earth's orbit.
Although I didn't know we had seasons in California here? Do you have seasons where you live three hours away?
We had a hurricane two weeks ago.
That's not a season, that's a weather event.
Now we have a hurricane season.
Yeah, it happens once three hundred year ins.
Or something something like that. No, of course, things are very mild, and as you get towards the equator, things get milder and milder. These seasons are more dramatic at the axes, where the tilts has a bigger impact.
Well, no, actually it's more dramatic. If you're closer to the poles, then the seasons are more dramatic due to the tilt.
Right, Yeah, you're right. It's milder if you're near the equator, and more dramatic if you're near either of the poles, which is why, for example, at the North Pole the sun goes down in the winter and doesn't come up for months, and in the summer you can see the sun four months. Right, These effects are more dramatic, and they're all due to the axial tilt.
Right. So now Chris's question is, like, what if that tilt of the Earth of its spin axis was not just twenty six degrees, what if it was ninety degrees? So, like, what if our spin axis was kind of in the same plane as the disk of the Solar System.
Yeah, it'd be awesome and strange, but first of all, it'd be very weird from a physics point of view, Like, it's not a coincidence that all the planets are orbiting around the same plane and that happens to line up with the axis of the Sun. It's because of conservation of angular momentum. The original blob of stuff that formed the Sun and the planets had a single overall spin, and that spin can't go anywhere. It has to stick around. So everything that forms from it eventually has that spin. So anything that's spinning in a different way is due to something happening, like a big event. For example, Urinus has an axial tilt of nineties deven degrees, and we think it's probably due to some huge collisions. Something came in balked Urinus and gave it a different kind of tilt. That's the kind of thing that needs to happen to have a big tilt.
Yeah, I was going to say, like Urinus has a tilted spin axis kind of like Chris is asking about, right, Like Urinus is flying through space kind of like a football in some cases, right, like an American football.
Yeah, it's spinning along the direction of its motion, whereas the Earth is spinning more like a basketball on the fingertip of a Harlem lobe trotter as walks across the basketball court.
Now it urinus spin axis is pointing towards where it's moving sometimes of the year, right of its year, like it's always pointing towards like, let's say the center of the Milky Way or something like that, even as it goes around the Sun exactly.
And that was the other part of Chris's question, whether the axis would always be towards the Sun or along the orbital path or what. And conservation of angle momentum tells us that it always points in the same direction. You can't have like a spin that follows your orbit perfectly like a football, because and the direction of that spin would be changing as you go around the Sun, and that takes a tork. It takes some kind of external force. There's nothing to apply that. So as the Earth goes around the Sun, the direction of its axis doesn't change, right, which is why the north pole sometimes further from the Sun and sometimes closer to the Sun. And the same is true for Urinus. It's always pointing in the same direction as it goes around the Sun. The direction of its spin. Its axis doesn't change, so neither is always pointing towards the Sun or always pointing along its orbit. As you say, it's always pointing in the same direction.
Yeah, And in fact, sort of I imagine the spin of Urineus actually sort of keeps That helps keep that axis from moving or changing, right, because then you have angler momentum pointing in one way, and so as it goes around the Sun, it tries to stay in the same direction.
Yeah, exactly. It's like a big gyroscope, like a huge planet sized gyroscope, always keeping its spin pointing in the same direction.
All right, So then the question is what would the weather be like if the Earth was spinning sideways, kind of like uranus.
It would be more severe seasons, right, it'd be warmer summers and colder winters.
Mmm, what do you mean?
The Earth rotates every twenty four hours, right, And if the Earth axis is aligned with the Sun axis, that means you see the Sun every twenty four hours because the Earth turns and you get a view of it. But if the Earth axis is tilted, then is rotation can't show you the Sun? Right, There's no way for the Earth to rotate to show you the Sun. The only way to see the Sun is to wait for the Earth to go around the Sun. So you are now on the sun side of the Earth.
That's only if you're like in the north pole of this tilted Earth, right, But if like if you're in the equator of the tilted Earth, some parts of the year, you would see the sun every day, right.
Well, I think half of the Earth would be in darkness and half the Earth would be in sun and the equator would be the dividing line between.
Those, right, Like if your spin axis was pointing directly at the Sun or directly away from the Sun, then yeah, half of the Earth would always be in darkness, half of the Earth would be in daylight, no matter how it spins. But then that's the axises pointing. I get the sent But on the other parts of the times of the year, right then everyone sees a day right.
Yeah, that's right. So you have very dark winters and then in spring and in fall you do have daytime and nighttime, and then it's summer it's one hundred percent sun. So the effect is more dramatic seasons.
Yeah, so like never mind the seasons, Like your day to day would totally vary depending on the year, right, Like in some parts of the year, six months a year, everyone would have like a twenty four hour day, but then the other parts of the year, you'd it'd be like living in the North or South Pole, like you never get sunlight or you would never get nighttime exactly.
You'd have continuous daylight for months and continuous nighttime for months, and then periods in between where you had short days or short nights. So it'd be very dramatic, be like currently living at the North pole or the South pole.
But then that would be sort of your daytime experience or what I wonder Chris's question is what would the weather be like? Like, would the weather be different, would we get like super crazy storms, would everyone on one side of the Earth, would you get no weather at all? What would that be like?
So it would mean more severe seasons, which probably means more storms, right, Hotter summers, more energy in the oceans, more storms being formed, deeper winters, more snow falling, which means more dramatic melt off, which means more flooding. So I think it means more dramatic weather events, right.
I guess like if the spin axis is facing the sun right, and like the top half of the spinning Earth gets sun twenty four hours a day, then things would sort of overheat, right, I guess, like if there wouln't be any poles, maybe things wouldn't be melt, but then when it gets to the other side, things will probably freeze on that part of the.
Earth m m exactly. But in order for the Earth itself to like freeze and form ice sheets and ice ages requires cool summers. So when you have less severe seasons, when you have cool summers and mild winters, like if the Earth had less tilt, you would actually get more ice build up. And if you have more severe seas since warmer summers, even if you have colder winters, you don't build up that ice because the warm summer obliterates it.
So then hear you, what would happen just be more extreme, Like you would freeze a half of the year and you would roast the other half of the year.
Yeah, exactly, So you'd have to get more into extreme sports, more surfing and snowboarding.
Yeah. I wonder if we would even be alive, Like, what could life evolve in a planet like that?
I think that some kind of life certainly could. I mean, even our situation is kind of weird if you approach it with no priors, but some kind of life could evolve. It would have different strategies and different rhythms for sure, and that would be fascinating. And we've looked actually at exoplanets to try to understand like, how common is our kind of tilt? What kind of tilts are out there? We'd love to know that about exoplanets, to get some sort of context for what's happening, but it's very difficult to measure the spin of exoplanets.
Although just from our Solar system, it seems like having a spin a line with your Sun is the norm, right.
Yeah, the normal thing, if they're there are no collisions, is to be aligned with your Sun. But how likely is it to have no collisions? In our Solar system? Venus is spinning like the wrong way, Urinus is tipped over, so it seems also not unusual to have big events and weird spins, though this is just from the one example of our solar system. We do know, however, that the Earth spin is changing. It's around twenty three degrees now, but it's not constant.
Wait, what what do you mean?
So it changes because the Moon pulls on it and other planets pull on it. Again, the Solar system is a chaotic place. Nothing is a simple two body system with a stable orbit, And over the last five million years, the Earth tilts has varied between twenty two and twenty four degrees, so it goes back and forth with a period of like forty thousand years.
Whoa like it has a wobble to it.
Yeah, it has a wobble. It has a big wabble over forty thousand years, and then a smaller wobble every like nineteen years. They call it a nutation, and that's due to the orbit of the Moon not being aligned with the orbit of the Earth Earth. It's like tilted a little bit or relative to the plane of the Solar System, so it tugs on the Earth a little bit differently as it goes around, and this tweaks the Earth a little bit, so there's like a big wiggle and then a little wiggle inside it.
I wonder how we've measured that, Like, how do we know that the tilt is changing over forty thousand years.
So we've been making these measurements over about the past thousand years, and then we can project back using our model of the Solar system. So a lot of this is speculative. It's like understanding the gravitational effects and projecting it backwards. We can model these things. We can also project it forwards. We know that the Moon is drifting away from the Earth, which means it's going to have a weaker and weaker effect gravitationally on the Earth, and a lot of the models I was reading about suggests that the Moon has a stabilizing effect on the Earth's tilt, like it does cause it to wiggle, but it prevents it from getting pushed out by even larger forces like Jupiter or Saturn or other orbital resonances. So it sort of like stabilizes the Earth, which means as it drifts away, it's less and less able to stabilize the Earth. One paper I read suggested that if the Moon drifted away, if we didn't have a moon, then within a few million years, the Earth's axis would be ninety degrees. It would be knocked totally over by orbital resonances and chaotic behavior in the Solar system.
Yikes, it's a good thing we have the moon then.
Yeah, exactly, think you moon.
Oh no, how we even got this tilt in the first place, the twenty three degree angles. Was it because of the impact we had maybe when the moon was formed.
Yeah, that's a leading theory. It has to come from outside the angular momentum of the Solar system to get that kind of tilt. And we think the moon was formed by a big collision with a proto planet, and so that might have done it.
All right, Well, I think that answers the question for Chris, what would the weather be like? It'd be pretty extreme. Like, first of all, your day to day would be really different, like sometimes of the year you would have a day cycle, but then the other half of the year you would have either complete darkness or complete daylight all the time. And then that would make the weather more extreme.
Exactly. Maybe McDonald's would be open twenty four hours a day, giving lots of young people jobs.
Or maybe closed twenty four letting people eat more healthy.
Perhaps, yeah, or stay at home and develop their cartooning skills.
That's right, then they get a smarter All right, let's tackle these other questions about quantum mechanics, the structure of the atom, and also the fundamental nature of the universe. But first, let's take a quick break.
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All Right, we're answering listener questions your today, and our next question comes from Josh.
Hi Daniel Jorge. I'm a big fan of the show. I know that quantum mechanics is necessary to describe our universe in the way Adams form, but it has of course been a somewhat unsatisfying theory to many, including that guy Einstein, given how strange and unintuitive it is. That got me wondering would it be possible to engineer a different atomic structure governed only by classical mechanics rather than quantum mechanics that would look roughly the same when zoomed out? So could there theoretically be a different universe that looks similar to ours, governed only by classical mechanics. Thanks so much for considering this question.
Hmm, interesting question, Thank you, Josh. All Right, I think he's saying that he doesn't like the universe and he wants to change here.
He's gotten news.
Yeah, he's got opinions about the structure of the universe.
Yeah, he's like, I like what you've done here. Mostly we just have a few thoughts about what's going on inside the atom.
I wonder if he's more asking like, could you change it? Could the nature of the universe be different and not and not be noticeable.
Yeah, he's wondering if behind the curtain of atomic structure, we could like re engineer it to be classical, to not follow the quantum rules and still reproduce the world that we experience. It's a really cool question because you know, one hundred years ago, that's the direction we were headed. We thought we understood physics the way things move, the way things spun, and we thought as we zoomed in on matter, we would find the same rules apply, that the atom really would be like a tiny solar system. So that's sort of what physics expected to find up until about one hundred years ago.
Right, and then he said we got quantum mechanics and not even Einstein seemed to like even Eistein gave it a bad review.
Yeah, well, it certainly was not what we expected. It was counterintuitive. We discovered that electrons are not tiny little dots of stuff moving in smooth classical paths the way other stuff does. It follows a different set of rules. And we discovered that because we saw things operating in ways that classical physics just could not explain. So I love the part of his question where he says when zoomed out, like he gives up explaining the atomic structure when you zoom in and examine the quantum nature of the universe directly in the eye, But he wants to zoom out and say, could we build our classical world without quantum mechanics as an underpinning right?
Well, it's interesting. I think he said first of all that he finds quantum mechanics unsatisfying and unintuitive. I wonder if you feel the same way. Do you find it unsatisfying when.
You're first learning quantum mechanics. He certainly find it frustrating because it doesn't give you the kind of answers you're used to getting. What it teaches you, though, is you have to ask different kinds of questions, and in the end getting a different kind of answer is really teaching you more about the nature of reality. Things that are weird and counterintuitive and surprising are always more informative, right, That's how you're learning, You're updating your model about the way the universe works. In the end, I just want to know what the universe is. I accept it. You know, universes are universes.
Yeah, and he also said he finds it unintuitive. You know, that's a kind of an interesting statement, you know, because intuition kind of depends, right, and your intuition can change as well.
Yeah, that's certainly true. And eventually, if you play with quantum mechanics long enough, you can develop quantum intuition. But most of us have a classical intuition. We imagine that things move smoothly, that they always have a location and velocity. So the idea that things can have like only probabilities, and those probabilities can interfere in weird ways and they follow fundamentally different rules. It's definitely unintuitive.
When you develop that intuition. Do you call it quintuition? I will now, yeah.
Coin here on the podcast, but there is this part where he talks about being zoomed out, like how our world is, and I want to make sure the listeners understand that most of the structure of our world, what we do experience, the things that developed our intuition, these aren't built on a quantum platform. Like most of the nature of the world we experience comes from the underlying quantum mechanics. When you zoom out how the atom is formed, and how light it's ebmitted, and whether things are transparent, and all of chemistry, all these things are built on essentially quantum properties of the atom.
Well, I think that's this question is like, could you have a universe that behaves that way at the macro level, but that doesn't have quantum mechanics at its core, Like does the universe have to have to be random at the atomic particle level or could it be deterministic for example, and not be quantum.
Well, not all of quantum mechanics is random. There are branches of quantum mechanics like boemium mechanics, which are deterministic, so that's not actually even necessary to be fundamentally random. But there are essential elements of the atomic structure which are quantum mechanical, which are very challenging for any sort of classical physics to reproduce. For example, even just the structure of the atom. Like if you try to build an atom as a tiny little electron orbiting in nucleus like a little solar system, right, and you said, it really has an orbit, it really has a location and a velocity. There's none of this uncertainty stuff. Everything is somewhere all the time. You would find that that is not a stable orbit. The same way that, like the Earth eventually will spiral into the Sun, that electron eventually would spiral into the nucleus because everything that's in orbit radiates away some of its energy and would eventually collapse. So the simplest idea classical atom just doesn't work. Doesn't mean that it's impossible to develop a classical atom, but there are big challenges there.
What if you adjust or add something new to classical theory, Like that would be like an electron would fall into the nucleus eventually if we only had certain the forces that we know about now. But what if there was another force that pushed the electron out or prevented it from falling in.
Well, anything that's in orbit, anything that moves in that pattern, is accelerating and it has to radiate. Any classical object at least, that's pretty unescapable even if you add another force. But you're on the right track. There is actually an alternative theory of the electron that uses just classical waves. It gets around this problem with the electron radiating away its energy by saying, maybe the electron isn't a particle, it actually is just deeply a wave, and it finds a wave solution to the atom. There's a paper by Rishikovsky in twenty sixteen. I remember reading it when it came out, and it's a very radical reimagining of how the atom works. And you give up both quantum mechanics and the concept that the electron is a particle at all. It's just like a wave solution. It says, the electron fundamentally is a wave, not a quantum wave, but a classical wave.
I guess maybe it would help to break down what you mean by something being quantum, right, because quantum means both it has a wave nature and also that it's random in its fundamental nature. So are you saying, like, if you take out one of them, you could still have a wavy electron.
I would say, what makes something quantum is that it obeys the Schrodinger equation instead of like classical equations, Shortinger equation is a fundamentally different equation. It says that the laws of physics do not apply to a particle or to the wave itself, but to this other thing, the wave function, from which you can then derive where things are likely to be. It's really a very different way to start your physics. You know, you don't just say, like F equals M and from that everything flows. You start with a completely different equation and from that everything flows. And where does that equation come from? You know, it just sort of came out of Schrodinger's head, and Heisenberg came up with another one, and we use it because it works, because it reproduces what's out there in the universe. So I would say that's sort of what defines something as quantum mechanical, that it deals directly with the wave function rather than with the actual motion of the object.
But then you were saying that it might be possible for an electron to be a wave but not be random.
Yeah, exactly. So there are these classical wave theories, like the original theory of light was a classical wave theory of electromagnetic fields that were oscillating. This was Maxwell's theory before quantum mechanics came along, and it said that light was a classical wave, that it operated the same way that like waves in the ocean do, that the fields always has very specific kinetic energy and locations and all this kind of stuff. So you can have a classical wave theory. And there are some theories of the atom which are built on classical waves, so they're not random, they're not quantum mechanical, and they do have this alternative view, but there's a lot of challenges there. It's not like they've worked out a complete theory of physics using classical waves for the atom. It's just really sort of a directionist start. People are saying, is this possible?
So then you're saying, like, the main thing that would not make the classical universe work is that the electron would eventually lose its energy and fall into the nucleus. But why doesn't that happen in quantum mechanics.
So in quantum mechanics that doesn't happen because those same rules don't apply. The particle doesn't have an orbit, it's not moving in a circle, it's not accelerating, so it doesn't have to radiate. In quantum mechanics, the particle doesn't have an orbit. It has a quantum state, which is a solution to the Shronninger equation, and that quantum state has a minimum value which is not add zero. Like all quantum particles have a minimum energy to them. It's impossible for a quantum particle to have zero energy. If it had zero energy, it would violate the Heisenberg uncertainty principle, which tells you you can't know the position and momentum simultaneously. Something is at zero energy, You know where it is, and you know how much momentum it has zero So boom, you violated the rules.
But doesn't that mean that there's some sort of like fundamental energy to the universe or force that's preventing all of these particles from collapsing.
It tells you the fundamental nature of these objects is that they have to have a minimum energy. They just cannot satisfy the equations we use to describe these physical objects do not have solutions with zero energy. The universe just does not do that. So yes, it's a fundamental property of the quantum nature of these objects.
I guess couldn't you have that in a classical theory, like you could have an electron orbiting the nucleus sort of like a little planet around its sun. But then there's some rule to the universe. It says it has to have a minimum amount of energy, and so that prevents it from collapsing.
That's the direction this classical electron wave theory is going, is saying, let's avoid being a particle that has acceleration. Let's just find solutions to the waves. Because in quantum mechanics, the way you get around this is finding the solutions to the shortening equation, which is a wave equation, and so they're trying to build a class wave equation that has similar structure to it that avoids those minima in the same way. That's the reason why maybe this classical wave theory could ever work.
Right. But I mean, you're sort of basically saying the same thing as quantum mechanics, right, Like quantum mechanics saying, no, you have to have a minimum you can't collapse. Well, why if I make a classical universe where I say you can't collapse either.
Yeah, and you can try to go that way. It's going to be really challenging to reproduce all of the features of quantum mechanics right in physics. It's easy to sometimes pick at one particular theory, say I have another theory which explains that better. Yeah, that's cool, bro, But we have lots of things that you have to explain. Not only do you have to explain why the atom is stable, you have to explain why there are quantized energy levels to the nucleus. You have to explain why we see spectral lines. You have to explain why some things are transparent, and why some things have certain colors. All of these things are due to the quantum nature of the atom and the energy levels. All of chemistry comes out of this, so you have to explain much more than just keeping the atom stable. So it's a huge challenge.
Yeah, Bro, Yeah, Bro, I don't believe Bro. I feel like you've had this argument in your head now for a long time.
No, this is me picking up my daughter's slang. She calls me bro. Whenever I try to talk physics.
To me, did you inform her your her father, not her brother.
Whatever. I try to explain some physics to her, she says, cool, story, Bro.
Now does she staid bro o or b r u h. You know that that's totally a different connotation.
I'm gonna have to listen more carefully.
I think maybe I wonder if you should just stick to Josh's question, Like, I know, it'd be really hard to make all of the universe be explained without quantum mechanics. But let's say, like his question about the atomic structure, could you make an atomic structure that works without quantum mechanics, And it seems like the answer is yes.
Maybe I think the answer is yes, it is possible. I don't know about this classical wave theory, but you can go much more baroque. You know, if you just need to reproduce all of chemistry and the atomic structure and the spectral lines and all these behaviors of the atom, you could engine you like a little machine that has really complex interaction that does all this kind of stuff. It wouldn't be simple. In order to reverse engineer all this behavior. You have to fold it a lot of really complicated stuff. One of the beautiful things about quantum mechanics is that it is pretty simple. You start from a single equation and everything else flows from that, and that has sort of a ring of truth to it. You could always replace physics with like a huge, complicated Rube Goldberg like device that does the same thing. It just wouldn't have the same explanatory power.
Mmm. But I guess you're also shouldn't be led by oakrams razors all the time, right, Like, just because something simpler in it doesn't mean it's true.
Yeah, exactly. The universe could have been an incredibly complicated, steampunk engineered version of the universe, with like all sorts of pulleys and things rolling down planes and bonking into stuff and banging with themselves with rubber chickens in order to release a little packet of energy which then goes into your microscope. Like that certainly could explain the universe. You could engineer a steampunk version of the atom that gave you the same experience and zoomed out, And.
In that universe, your daughter wouldn't say yeah, Bro, should say yeah, Baroke, which is which is a terrible truth?
I laugh at all your jokes terrible or not?
Yeah, Bro? All right, Well, I think that ANSWER's Josh's question. Would it be possible to engineer a different atomic structure that doesn't follow quantum mechanics. Uh maybe, yeah, it's possible, I guess, but you're saying probably not because quantum mechanics is so convincing, not just in its simplicity, but it's an ability to explain not just the atomic structure, but other things about the universe. All right, well, let's get to our last question of the day, and this one is pretty interesting. It's about the fundamental nature of reality and also radical angles. So let's stick into that. But first, let's take a quick break.
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All right, we're answering listener questions. We've answered questions about the tilt of the Earth and how different weather would be, and also about the fundamental structure of the atom and quantum mechanics. And now we are attacking something a little bit more radical.
And I have a question that I hope you think is rad. I was wondering, when we analyze the universe using a spherical coordinate system, would there be such thing as a plank angle, That is, would there be such thing as an angle below which we can't resolve the universe anymore? Finally, a fundamental pixel of rat. Thanks you guys are dope.
You're dope, Bro, I canna say we're rat and dope and Bro I like answering. I feel like he's our age. He's using the same lingo.
I think his question is super awesome. I really love this question.
Is it tubular? Totally tubular? Or is igneto?
I love it because it relates to the fundamental nature of reality, but also to the systems we impose on that the way we think about it, Like, does it matter if you're thinking about the universe in xyz or in polar coordinates and R data five? Does that have an impact on the universe itself?
Yeah, because, as we just talked about, the universe is quantum mechanical, which means there's a minimum amount of energy like matter can have. And that's also made physicists think that maybe this quantumness applies to space itself.
Right the quantum mechanics tells us that everything is discrete, nothing is continuous, There are no smooth pass or no real numbers. You can have like one electron or two electrons, but not one point seven. That everything is like in pixels or on a ladder. That things are chunked right, not smooth. And that makes people wonder if space itself is pixelated. If you zoom in far enough on the screen in reality, you can actually see those quantum pixels.
Yeah, it's a theory suggested by quantum mechanics and physicists has sort of a candidate for what that minimum distance in the universe can be, right.
Sort of. I think this is really over sold. I mean, we have like a back of the envelope sketch of maybe the vicinity of the region in which that number might fall, and we use it all the time because it's the only estimate we have. But that doesn't make it any good. You know, if we call this thing the plank length, and you arrive at the plank length by taking all the constants that we know about gravitational constant, the speed of light, these kind of things, and arranging them in a way, multiplying them by each other square rooting them, et cetera, et cetera. So you get something with units of distance, and that's saying, well, maybe that's a fundamental number in the universe. Maybe that distance means something. Oh, and also maybe it means that this one particular thing we're wondering about distance the shortest possible distance. It's very, very handwavy kind of an.
Argument, right, But it's called the plank length, right.
Yeah, it's called the plank length. Or you can make a version of it in time, which is the plank time. Or you can make a version of it in energy, which is the plank energy. So in general terms we just call this the plank scale. It's a short distance, high energy, short amount of time. And I want to really emphasis that this is simultaneously like a terrible estimate of this distance. It's like saying, you know what is horror salary as a cartoonist, Well, I know that answer is in dollars per year, and then just doing any random calculation that gives you an answer with the right units and saying, oh, the GDP of the US is three trillion dollars per year, so therefore that must be horge salary because it has the right units.
I can't confirm or deny that.
Just having the right units doesn't mean you're the right answer right. On the other hand, it's the best estimate we have because we have no idea how to do anything better. So that's why you hear it battered around a lot, because it's the best terrible estimate we have.
Yeah, it's called the cham salary. It's the minimum amount of money a human being can while still having fun all the time.
Yes, I want to alert IRS agents who might be listening to the podcast that Jorges Return will feature three trillion dollars this year.
Yeah, that's so we don't have any attorneys or CPA is.
Listening, right exactly. And that's a ridiculous example because it's a terrible estimate, just like the plank length is.
It's sort of a tourt way to get at it. But it's sort of like the idea is like, well, we have all these fundamental things in the universe. If you mix them up, maybe it gives you sort of a sense of the length of things, below which the universe just doesn't make sense.
Yeah, it's probably correct to within a factor of ten to the trillion. Yeah, there you go by which I mean ten, and then the trillion.
Zeros like, sure you don't know either way, right.
No, you don't know either way. You really have almost no information. It could turn out to be totally bang on, It could turn out to be close, It could turn out to have nothing to do with the universe at all.
I see, I see how strong opinions about the plank length, like you have more than a plank length of well thoughts and apparently negative feelings about the planklinth.
I want our listeners to understand what we do know and what we do not know. And I see in popular science a lot that people refer to the planklink as the minimum distance scale the universe. We don't know if the universe has a minimum distance scale and what it is, and if the plank length is anywhere close to it.
There's a lot we don't know. But I think the idea is that maybe it's like it's like a big maybe, like maybe the universe has a minimum distance below which things just don't exist or don't make sense or things.
Are fuzzy mm hmm exactly.
And you said that applies to distances and to time, And now I think ANSWER's question, as s'ce radical awesome, totally tubular question is can that idea be applied to angles, like is there maybe a minimum angle to the universe?
Yeah, And it's really sort of asking what is the most natural set of units for the universe? Is it x, y z or is it r A theta five? Where should we apply this distance too? Like what kind of unit? An angle particularly tricky because you know, if you make a triangle and you make it really really long, the angles can get really really small. Imagine a triangle it's like one millimeter on one side and a light year on the other two sides. That angle would be pretty tiny and so almost zero, right, almost zero exactly. And so I think the short answer to this question is that there shouldn't be the shortest angle because we think that the Cartesian coordinate system is a natural way to describe the universe. And that's because those are the directions along which momentum is conserved. And it's this conservation momentum and the uncertainty of momentum position together that gives you the Plank constant, which gives you the Plank scale, and that's naturally described in linear coordinates. An X, Y, and Z.
It sounds like you're leaning towards no. But like, what if I I don't know. Just take some of these fundamental things in the universe, like the plank length and maybe the distance of the universe, and I make a triangle for one side is the plank length and the other two sides are the width of the universe. Wouldn't I get maybe a minimum angle to the universe.
Yeah, exactly. I love that construction. So you're imagining a triangle. One side is the plank length in like X, and then the other point of the triangles across the universe. Would that effectively be a minimum angle? And the answer there is yes. If the universe has a finite size, that would limit the size of your triangle in one direction, and so it would be a minimum opening angle of that triangle. But we don't know if the universe is finite in size or if it's infinite. If the universe is infinite in size, then there's no limit to the size of your triangle. You could have a plank length on one side and infinite lengths on the other side, making that angle zero.
I wonder if you need an infinite universe to disprove an infinitely small angle, Like, couldn't you have an infinite universe but also have a minimum angle? Right, Like, you can have an infinite universe and still have a minimum distance or minimum time, even though time might be infinite. Couldn't that also apply to angles?
Yeah? And I love this question because anytime I make an argument, there's like two different possible loopholes, so you can go the other way and here there I think there are really two different loopholes. One is you don't even need an infinite universe. You just need like a curved universe. Imagine a universe that's closed what it loops around on itself, And principle, you could draw a triangle that like loops around on itself, like on the surface of a sphere that's essentially infinite, right, And in that case you could have an arbitrarily small angle. And the other side, I think you're asking about whether angle itself could be fundamentally limited, not as a product of the limitation of space or time, but angle itself could be fundamentally limited, and it's a possibility. We know that quantum mechanics has a very strong relationship too. Angles two rotations, For example, we know that angular momentum how you spin, is quantized, whereas linear momentum like how you move, is not quantized. I mean, you can have any value of kinetic energy of velocity as you fly through space, but there are certain limited values of angular momentum that are allowed. Angles are in some sense more naturally quantized than distances.
But I think you're referring to quantum spin, right, are you referring to quantum spin?
Well, quantum spin is an example of angler momentum, and it's also quantized. But even just anglar momentum is quantized, like the angle momentum of the electron in its quote unquote orbit around the nucleus is quantized for the same reason that the electron energy levels themselves are quantized. That it overlaps on itself. The electron state envelops the entire atom and overlaps itself, and so it has to satisfy certain boundary conditions, which is where quantization comes from. So not just quantum spin. Even orbital angular momentum like the Earth going around the Sun is quantized.
But couldn't you say the same about its distance, like the width of its orbit. Perhaps that it's also quantized In that way, you.
Can always relate angular momentum to linear momentum. That's true, right. Anglementum in the end is just linear momentum around an axis, but the angler momentum is quantized that the linear momentum is not. And that's something we don't understand, I think, more deeply than what already explained. But it points to angles being important to quantum mechanics. I've never seen a calculation directly of the plank angle. One issue is that radiance, for example, although they're super rad they really have no units other than radiance. They're just numbers, and so it's not hard to put together fundamental constants to just give you a number. But an interpreting as an angle is kind of a stretch.
But I guess you know, just like you can't assume that the universe has a minimum distance or pixel to it just because electrons are quantized, you know, you also can't assume that, just because anglo momentum is quantized, that the universe itself has a minimum angle to it.
Yeah, exactly, you can't. It's just suggestive. It just tells you that angles are kind of quantum mechanical. It's not a concrete proof, or even really a strong piece of evidence that angles themselves are quantized, and if I had to guess, I would guess that they're not. I think probably the universe is infinite, and you can draw as long a triangle as you want with the smallest angle possible.
Are you also guessing that it doesn't have a minimum distance.
Even if it does have a minimum linear distance. If the universe is infinite, remember, you could make as long a triangle as you want, and so as small as angle as you want. I think that's probably the universe that we.
Live in, if it's infinite, If the universe is infinite, If.
The universe is infinite, which again we don't know.
I wonder even if it's not infinite, like if you start to get into limits of like just practicality, like at some point it's so far away you can never measure this triangle, right.
Yeah, that's a good point. Because of relativity, the idea that a triangle could exist across the universe is a fuzzy notion because points separated in distance are not well defined in time, and so like measuring a triangle across the universe, can such a triangle even really exist.
And I guess then in that case, and this gets very philosophical, the limitation is not like a fundamental property of the universe. It's just like it's just not possible to do it. But it might be there.
Yeah, exactly the same way that like some of the velocities we talk about with galaxies. We talk about those velocities, but you could never actually measure them. In the same way, it might be something you couldn't act sally measure even if it isn't the fundamental property of the universe.
All right, Well, then it sounds like the answer for Anson is that it's possible that the universe has a minimum rad angle to it. But Daniel the physicist says, no, bro, I don't think that's true, which is totally a bummer dude.
But I do like the idea that there's a minimum amount of rad in the universe. You know, it's just sort of like relaxing to know that, no matter what you do, there'd be a minimum radness to the universe.
Yeah, everybody's rad. Everybody has a minimum amount of rad.
If there's a minimum radness and the universe is infinite, that technically means it's an infinite amount of radness for us all out there to enjoy.
Yeah. I guess you just need to look closely, I guess, or keep asking questions.
That's the recipe for a happy life.
Yeah. Now the big question is that do you want fries with that?
Daniel?
Do you want fries with that?
Bro depends? Is the cartoonist paying with this trillion dollar salary?
No, there's a minimum amount of generosity that the cartoonists have. Okay McDonald's us are too expensive apparently.
All right, I know what our friendship is worth.
All right. Well, that answers all of our questions for today. We'll be answering more questions in future episodes. If you have a question, please send it in.
Wright to me directly Daniel Whitson at gmail dot com, or write to us to questions at Danielanhorge dot com, or find us on Twitter just google us. We're not hard to find and we really do answer all of our emails.
All right. Well, we hope you enjoyed that. Thanks for joining us, see you next time.
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.
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