Daniel and Kelly’s Extraordinary Universe - Daniel answers Listener Questions about diamond rain on Jupiter, travel near the speed of light and the tilt of Uranus.

Episode Date: February 23, 2021

Daniel answers questions from listeners like you! Got questions? Come to Daniel's public office hours: https://sites.uci.edu/daniel/public-office-hours/ Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

This is an I-Heart podcast. Have you ever wished for a change but weren't sure how to make it? Maybe you felt stuck in a job, a place, or even a relationship. I'm Emily Tish Sussman, and on She Pivots, I dive into the inspiring pivots of women who have taken big leaps in their lives and careers. I'm Gretchen Whitmer, Jody Sweetie. Monica Patton. Elaine Welteroff. Learn how to get comfortable pivoting because your life is going to be full of them.

Listen to these women and more on She Pivots, now on the IHeart Radio app, Apple Podcasts or wherever you get your podcasts. Don't let biased algorithms or degree screens or exclusive professional networks or stereotypes. Don't let anything keep you from discovering the half of the workforce who are stars. Workers skilled through alternative routes rather than a bachelor's degree. It's time to tear the paper ceiling and see the stars beyond it. Find out how you can make stars part of your time. talent strategy at tear the paper sealing.org.

Brought to you by opportunity at work in the ad council. The U.S. Open is here and on my podcast, Good Game with Sarah Spain. I'm breaking down the players, the predictions, the pressure, and of course the honey deuses, the signature cocktail of the U.S. Open. The U.S. Open has gotten to be a very wonderfully experiential sporting event. To hear this and more, listen to Good Game with Sarah Spain, an Iheart women's sports production in partnership with deep blue sports and entertainment on the Iheart radio app, Apple Podcasts,

or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. Is our corner of the universe weird? For the longest time, we thought that Earth was everything. When people used to wonder about the nature of the universe, they were mostly thinking about the rules for how things worked down. here. Even the stars just seem like sort of decorations in the sky. Now, of course, we know that

there's much more out there. And our little slice of this planet is the tiniest fraction of the space in the solar system, which is an infinitesimal speck of the volume of the galaxy, which of course is a tiniest drop in intergalactic space. And the stuff that goes on out there in the rest of the universe is super crazy. It's a bonkers universe out there filled with black holes and pulsars and giant jets and crazy conditions. So is our corner of the universe weird? Or is it the least weird place in the cosmos? Hi, I'm Daniel. I'm a particle physicist, and I have the weirdest questions about our weird cosmos. And welcome to the podcast, Daniel and Jorge Explain the Universe, a production of iHeartRadio,

in which we dare to ask the biggest questions about the biggest things in the universe. We explore the tiniest little particles and ask those tiny little questions about what those crazy little quantum objects are doing. but mostly we join you in the struggle to understand the nature of this universe that we find ourselves in but we marinate in the joy of that wonder and that curiosity we embrace it we ask those questions about the nature of the universe and we dare to demand answers we're not always satisfied with what we find but we understand it's a process science is not a list of answers it's a way of figuring out how the universe works it's daring to expect that we can actually understand the way the universe functions that we could hold in our head a model for how the

universe works and actually makes sense of it. That would be an exciting day. That is a day in the future, but until then we can peel it apart one little bit at a time and try to help you understand something about the nature of the universe. And to do that, we want to encourage you to ask your questions, to think deep thoughts about how the universe works, and to wonder when things don't fit together. And so for that reason, we love on this podcast answering questions from listeners. And so you probably notice by now it's just me here in the studio today. So as usual, I'm going to use this opportunity to catch up on some listener questions. And so on today's program, we have listeners questions about diamonds in Jupiter, about ships approaching each other

near the speed of light and about what knocked Uranus on its side. So thank you to everybody who writes in with their questions via Twitter, via email, or sends us an audio clip that we can actually use on the podcast. If you have questions that you aren't answered, we answer every tweet, we write back to every email. Please send us your questions to questions at danielanhorpe.com. We really want to explain the universe to you. And if you're too shy to send us questions, you can also drop into my public office hours, where I hang out on Zoom and answer physics questions from anybody and everybody, including follow-up questions and crazy hypotheticals.

So please come join us. If you want connection and schedule details about my public office hours, check out my websites at sites.ucy.edu slash Daniel, where you can find all the information. All right, so let's dig into some of these super fun questions from listeners. Here's the first one. It's all about diamonds. Hey, Daniel and Jorge, this is Andy in Indiana, and I just had a hypothetical question for you. Suppose it were possible to fly a spaceship up next to Jupiter at the very top of its atmosphere, and you tossed a piece of coal out the window.

Would it turn into a diamond before it hit the ground? Thanks, guys. I love the podcast. All right, so Andy and Indiana doesn't want to go to the market. to buy a diamond for an engagement ring and instead wants to fly to Jupiter, drop a piece of coal into the atmosphere, and see if that will turn into a much cheaper diamond. Well, I'm not sure that's a good return on investment given the expense of getting to Jupiter, but it's a really fun question about what actually happens in the crazy intense heat and pressure

of these gas giants. So let's break it down. How do you actually make a diamond? Like, how does that happen here on Earth? Could you just take a piece of coal and squeeze it really, really hard and form a diamond? Well, it's true that diamonds are just another form of carbon, right? And carbon has lots of interesting forms. Coal is mostly carbon.

Graphite is carbon. Nanotubes are carbon. You can assemble these little bits of carbon in lots of different ways that have lots of different properties at the macroscopic level. And to me, that's super cool that like the same basic building blocks, you can reassemble in different ways and get really very very very. different materials, right? It tells you that there's something deep about the arrangement of stuff. It's the arrangement of those carbon molecules that makes a diamond, a diamond and a piece

of coal, not the thing it's made out of. And that's a deeper truth that we've learned about the whole nature of the universe, right? That it's not what you're made out of, but how you're put together. And that's why, for example, you are made out of the same particles as 80 kilograms of lava or 80 kilograms of hamster. It's all the same stuff, just rearranged in another way. And that's the cool thing about diamonds. If you start from carbon and you get them under really intense heat and pressure, we're talking about like 2,000 degrees Fahrenheit, they will form this really interesting structure, which will then survive when it goes back down to lower temperatures, right? It's not like the diamonds form only in that intense heat and pressure and then sort of break

apart. You form this really intense thing under pressure and then it holds up when it gets back down to lower temperatures and lower pressure. That's the really awesome thing. It takes this energy to build it, but once it clicks into place, it's super duper strong. Now, you don't get diamonds under normal conditions on the surface of the earth. Most of the diamonds that are on people's engagement rings walking around come from like 150 to 200 kilometers below the surface of the earth. That's where the temperature is high enough and the pressure is intense enough to make it. But it doesn't come from coal, right? Most diamonds that we have are not the byproduct of coal getting squeezed because coal is

actually a relatively late addition to the earth's crust. Remember, coal is basically dead plants. Plants form and grow and they pull carbon out of the atmosphere and then they die and they get squished down and you get oil or carbon. All these fossil fuels are the remnants of. of dead plants, but diamonds have been forming on earth since well before there were even plants. And so the raw materials are the same for coal and for diamonds, but that doesn't mean that the diamonds we have actually form from coal, right? And also, coal tends to be in these sort of

horizontal seams. It's laid down in layers, whereas diamonds, we typically find them in these vertical pipes inside the earth. And the reason is that these diamonds are formed deep, deep under the Earth's surface, 200 kilometers, but for us to find them, they need to somehow get up to the surface of the Earth. And that's done by volcanoes. So you need these like vertical pipes of lava that carry the diamonds up from deep under the Earth's surface to near the surface where we can find them in mines. So that's where most of the diamonds come from. But there's actually another super cool kind of diamond that's made on the Earth's surface. And that's an asteroid impact diamond. Remember when a rock hits the earth, usually it burns up in the atmosphere. But if it's big enough,

it can make it all the way down to the surface of the earth and impact. And if it's large enough, that can have as much energy as like the explosion of a nuclear weapon. Remember, the rock that killed off the dinosaurs was a really big one. It tossed a lot of ash and dust into space blocking out the sun. So that was definitely capable of creating the conditions you would need to form diamonds. You get super high temperature when that thing impacts. And at the impact side, you also have really high pressure, which means you can form diamonds when they impact. And if you go to Meteor Crater, this crazy hole in the ground in Arizona, you can actually see these things. They find these millimeter size micro diamonds in Meteor Crater.

All right. So what would happen if you actually took a chunk of coal and went to Jupiter and dropped in there? Is Jupiter really capable of forming diamonds? And the answer is yes, Jupiter's like a diamond forming factory. Now, a lot of this is speculation or based on models, but we have ideas for what the pressure and temperature are in the various layers of Jupiter's atmosphere. And we have this from models that we've developed and then we can test them from various probes that have gone to visit the planets and gather a little bit of data and constrain those models. And those models tell us that in the interior of Jupiter, you do have the pressure and the temperature necessary to make diamonds. And for a long time, people thought that it was mostly Uranus and Neptune that were diamond

making factories because they have the raw materials you need to make diamonds. That is methane. Methane is a very carbonaceous molecule and so it has those raw materials. But these days, we think that Jupiter, which has less methane, also has enough to be making diamonds. And so what happens is you have this atmospheric methane. sort of in the higher levels, and then you might get, for example, a spark from lightning storms and the surface of these planets, and that can spark the formation of a diamond, which then

drops into the interior and gathers more material as it goes. And so these diamonds, which then get heavier, fall deeper and deeper and they grow. And nobody actually knows how big these diamonds can get. They might just be small, like super tiny nano diamonds and you have a whole lot of them, or it could be that they accumulate, like hail falling in the Earth's atmosphere, gathering up more and more water. You could even get these like massive diamond bergs, they call them, forming in the interior of Jupiter. The only way to really figure that out is to go and to probe it, but we haven't had a chance to do that yet. So we think that the conditions are right for Saturn and Jupiter to form diamonds, to have this essentially constant rain of diamonds. And according to calculations, they were produced tons and tons of diamonds every year.

So they anticipate there are something like 10 million tons of diamonds on Saturn and Jupiter. So if you could get a probe out there, you wouldn't need to bring your own coal. There are already tons of diamonds in Jupiter. But the question was about whether it would form a diamond before it hit the ground. Remember the definition of the ground or the surface of Jupiter is a question. bit fuzzy. There is a rocky icy core, but things get really dense before you even get there. And so a bit of coal that turns into diamond would probably stop well before it reached that rocky icy core. It would stop when it hits a point where it's equilibrated, right, where it has the

same density as the stuff that's around it. And we don't actually know what would happen to these things as they drop into the core of Jupiter. Because on Jupiter specifically, the conditions are so extreme that it might be possible that these diamonds form liquids. These diamonds get so compressed that you get like liquid diamond oceans on Jupiter. We think on Uranus and Neptune to contrast that the temperatures are much cooler and you don't reach that like 8,000 Kelvin degrees you need to melt diamonds. So Uranus and Neptune probably have huge collections of diamonds in their interior. But on Jupiter, those diamonds may have melted and contributed.

to these vast oceans of liquid diamond. It's fascinating that we still don't know really what's going on inside Jupiter. We know it's crazy. We know that it's very different from what's going on here on Earth, which makes it hard to extrapolate and hard to measure. But until we get more probes out there, dropping coal or just dropping instruments into the atmosphere of Jupiter, then we won't really know what's going on.

But it's a fascinating place to learn about what materials can do. You know, it's all the same basic elements, just playing different roles, just fitting together in different ways. And in some cases, you need special conditions in order to make them. But the amazing thing is that they last even after those conditions have broken. Even when they get pulled out into lower temperature and pressure conditions, we still have these literal crystals of knowledge that come out of those situations. So thanks, Andy, from Indiana for asking a fun question about dropping coal into the atmosphere of Jupiter. I want to answer a couple more questions, but first, let's take a quick break. A foot washed up a shoe with some bones in it.

They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases, but everything is about to change. Every case that is a cold case that has DNA. Right now in a backlog will be identified. in our lifetime. A small lab in Texas is cracking the code on DNA. Using new scientific tools,

they're finding clues in evidence so tiny, you might just miss it. He never thought he was going to get caught. And I just looked at my computer screen. I was just like, ah, gotcha. On America's crime lab, we'll learn about victims and survivors. And you'll meet the team behind the scenes at Othrum, the Houston lab that takes on the most hopeless cases

to finally solve the unsolvable. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation about exploring human potential. I was going to schools to try to teach kids these skills, and I get eye rolling from teachers or I get students who would be like, it's easier to punch someone in the face. When you think about emotion regulation, like you're not going to choose. an adaptive strategy which is more effortful to use unless you think there's a good outcome as a result of it if it's going to be beneficial to you because it's easy to say like go you go blank

yourself right it's easy it's easy to just drink the extra beer it's easy to ignore to suppress seeing a colleague who's bothering you and just like walk the other way avoidance is easier ignoring is easier denial is easier drinking is easier yelling screaming is easy complex problem solving, meditating, you know, takes effort. Listen to the psychology podcast on the IHartRadio app, Apple Podcasts, or wherever you get your podcasts. Have you ever wished for a change but weren't sure how to make it? Maybe you felt stuck in a job, a place, or even a relationship. I'm Emily Tish Sussman, and on she pivots, I dive into the inspiring pivots of women who have taken big leaps in their lives and careers.

I'm Gretchen Whitmer, Jody Sweeten. Monica Penn. Elaine Welteroff. I'm Jessica Voss. And that's when I was like, I got to go. I don't know how, but that kicked off the pivot of how to make the transition. Learn how to get comfortable pivoting because your life is going to be full of them. Every episode gets real about the why behind these changes and gives you the inspiration and maybe the push to make your next pivot. Listen to these women and more on She Pivotts now on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, we are back and we are talking about the crazy things that go on in our universe and answering listener questions about the extreme conditions that we find in our solar system and out in deep space. So here we have another fun hypothetical question from Cole.

Hello, Daniel and Jorge. This is Cole Packard and I'm from Reading, California. I'm a big fan of the podcast and I love listening to you guys while I'm driving. I was listening to your episode about how special relativity affects how we perceive time and it got me thinking. What if two observers were traveling towards each other both going near the speed of light? Would their relative velocities be close to twice the speed of light? Would the time distortion make each observer look extremely slow to the other?

Looking forward to hearing your answers. Thank you. All right. Thanks very much, Cole for asking a question about one of my, favorite topics, which is the crazy bonkers nature of our universe at high velocity. Because we here on Earth are used to things moving pretty slow. And we developed an intuition that tells us what happens when you throw a baseball. How fast is that baseball moving relative to the ground? And it turns out that intuition is just flat wrong. I mean, it mostly works if things are

moving slow, but it turns out the rules are actually fundamentally different. And that only when you get to very high velocities, velocities approaching the speed of light, do you see that intuition breaking down and reveal the true nature of the universe? But this is one of my favorite examples. This is why we push ourselves to understand the extreme situations of the universe because it's there that the truth is revealed. And we don't want just an intuitive understanding of the universe that sort of kind of works. We want to know the truth. We want to read the fundamental truth of the universe. We want to reveal its source code. We want to understand how the universe actually works,

not just some approximation that kind of works in some situations. So that's why I love special relativity and examples like this that make us try to understand how things work in crazy conditions. Now, Cole was asking us a fun question about what happens when two ships approach each other, each moving close to the speed of light. And also, what happens to the clocks on those ships? So Coles managed to touch on basically all the critical elements of special relativity. So to answer this question, we're going to need to remember a few things.

First, remember that all speeds are measured as relative speeds. You can't talk about a spaceship moving near the speed of light. You have to say moving near the speed of light as measured by who or moving near the speed of light relative to what because there are no absolute measures. There's no like reference frame floating out there in space that can measure the speed of a ship, you always have to say the speed relative to what. And it's especially important in special relativity because two different observers moving at different speeds will see the same ship and report different results. The thing we have to remember number two is that

we can't simply add velocities. You know, if you are in a car moving at 20 miles an hour relative to the ground and you throw a baseball at 20 miles an hour, how fast is that baseball moving relative to the ground? Well, you think, oh, that's easy. It's 20 miles an hour from the car plus 20 miles an hour from your arm, you go 40 miles an hour. And that's true for small velocities. But because in special relativity, nothing can go faster than the speed of light, you've got to change that rule. And it turns out that as you get too high velocities, you can't just add those velocities in a simple way. The velocities add in a really weird, nonlinear way.

And that's one thing that prevents you from going faster than the speed of light. So, for example, if you are in a spaceship flying at 7 tenths the speed of light relative to the earth and you throw a baseball with your amazing arm at 7 tenths the speed of light in the same direction, do we measure that baseball going at 0.7 plus 0.7 or 1.4 times the speed of light? No, we don't because you can't just add those velocities. Instead, you get something like 0.95 times the speed of light. things don't just add up linearly. And that's another thing that's going to make it really weird to observe the same events at different velocity. And the last thing we need to understand to answer Cole's question is how time is affected

by special relativity. And the thing to understand there is that moving clocks run slowly. If you see a clock that's moving away from you really, really fast, you will observe its time running slowly. All right. So with that in mind, let's dig in. to Cole's question. Cole says what happens if these two ships are approaching each other and both are moving

near the speed of light? So first, let's clarify if both are moving near the speed of light, who is measuring that speed? So let's put Earth at the center of that and say that one ship is coming at Earth near the speed of light and the other ship is coming at Earth from the other direction also near the speed of light. So we're on Earth and we measure ship one coming at us near the speed of light from Mars, for example, and the other one is coming the other direction and also near the speed of light.

Now, you look at those two ships and you ask yourself, how fast are they moving relative to each other? If these velocities were very, very slow, we were on the surface of the earth and you had, for example, two cars both coming at you at 20 miles an hour, you could say, oh, the cars are approaching each other at 40 miles an hour. But zoom back out to space, if both ships are approaching you at 7 tenths the speed of light. You can't say that they're approaching each other at 1.4 times the speed of light because the velocity addition is not linear. Instead, on each ship, they could measure the speed of the other ship and they would see something like 95% of the speed of light. And that works for both ships because the situation is symmetric. So on earth, we measure

each ship as coming towards us at like 7 tenth the speed of light, but each ship, but each ship, ship doesn't measure the other one is traveling faster than the speed of light because you can't just add the velocities linear. We have this crazy nonlinear velocity addition rule which changes things. Now here's a bit of a brain twisty part. The distance between the two ships as seen from Earth is decreasing at faster than the speed of light. That is from Earth, both ships are moving at less than the speed of light. But if you measure the distance between the ships from Earth, that number is decreasing faster than light could move between the two ships, right? Because that's just measuring the distance between the two ships.

And we see one ship going in one direction at seven-tenths of speed of light and the other one going in the other direction at seven-tenths of speed of light. So we see the distance between them decreasing at faster than the speed of light. And that's okay because nobody in the scenario is moving faster than the speed of light relative to anybody else. Because if you transform to the frame of one ship, They only see that distance decreasing at 95% of the speed of light. And that's the crazy thing is that different people can see the same events and report different answers.

And everybody can be correct, right? We can give different conflicting reports of the same scenario and all be correct. That's the most crazy thing about the universe I've ever learned about in physics, that there isn't one true history of the universe that we can. could all agree on. That if we all had accurate clocks and devices and rulers, then we could all figure out like, what really happened. There is no what really happened for the whole universe. There's a what really happened if you were at this location and moving at this velocity. Then there's another what really happened if you were over there moving at that velocity.

And the crazy thing is that they do not have to agree and they can all be correct. We talked about this in our episode about time dilation, for example. Different people might have different stories to tell about who won a race. And that's because the definition of now about whether two things happen at the same moment also depends on where you are and how fast you are moving. And that leads us to the second part of Cole's awesome question about time. You see, we know that moving clocks run slowly. That means that if you see a clock moving at high velocity relative to you, you will see that clock's time running slowly. So say both of these ships, which are approaching Earth at 7 tenths of speed of light in opposite directions.

Both of these ships have a clock on them and they have awesome telescopes so that the people on the ship can read their own clocks and they can also peer through these super telescopes to read the clock on the other ship. So you're on a ship, you're moving at 7 tenths to speed of light. Most people make the mistake of thinking that you will feel time as running slow. You won't. You always feel your time running the same way, running at one second per second. And if you look down at the clock in your hand, you will see it running normally. Why is that? Doesn't time move slow at high speeds?

It does, but it only slows down for moving clocks. And your clock, which is in your hand, is not moving relative to you. You are not moving relative to you. And that's why time passes normally for you. Now, if you look through your telescope and you look at the clock on the other ship, you see that clock moving really, really fast coming towards you at 95% of the speed. speed of light. And so you see that clock running slowly. You think for every 10 seconds the passes on your clock, you only see one second tick on that clock. So that's really weird, right?

Is time passing differently on that ship? No, you can't make statements about that. You can only make statements about what you observe because now flip it around and put yourself on the other ship, right? That other ship, they see their clock running normally. They don't see their clock running slowly the way you see it. They see their clock running normally. And when they look to their telescope, they see your clock running slowly. It's another example of how two people, two observers, can give faithful accounts, but come up with different stories about what happens. You say their clock is running slowly. They say your clock is running slowly. The physics part of your brain says, what, what actually is happening? And the answer is, there are different things happening based on

where you are and how fast you are going, right? Because truth and history are not absolute anymore. They are relative and they are a function of location and velocity. And you might think to yourself, how can that possibly be the reality? How can our universe actually work that way? Doesn't it lead to all sorts of contradictions? Well, you know, all of these effects happen when people are far apart or moving relative to each other at very high speeds. And so it makes it hard to spot these things. And you just have an intuition that the universe works in a certain way, that there's like a universe clock that ticks forward and the universe has sort of a state right now and then it ticks forward and has another state, sort of like a universal movie that's sliding

forward in time. But that's just not the situation. What we've revealed through our experiments is that things really do depend on where you are and how fast you are going, that there is really no absolute truth to what happens in the universe. All right, cool. Thanks very much for asking that super fun question. I want to get to one more question, but first, let's take another break. A foot washed up a shoe with some bones in it. They had no idea who it was.

Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases, but everything. is about to change. Every case that is a cold case that has DNA. Right now in a backlog will be identified in our lifetime. A small lab in Texas is cracking the code on DNA. Using new scientific tools, they're finding clues in evidence so tiny you might just miss it.

He never thought he was going to get caught. And I just looked at my computer screen. I was just like, ah, gotcha. On America's Crime Lab, we'll learn about victims and survivors. And you'll meet the team behind the scenes at Othrum, the Houston Lab that takes on the most hopeless cases to finally solve the unsolvable. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Dr. Scott Barry Kaufman, host of the Psychology Podcast. Here's a clip from an upcoming conversation about exploring human potential.

I was going to schools to try to teach kids these skills, and I get eye roll. from teachers or I get students who would be like it's easier to punch someone in the face. When you think about emotion regulation, like you're not going to choose an adaptive strategy which is more effortful to use unless you think there's a good outcome as a result of it if it's going to be beneficial to you because it's easy to say like go you go blank yourself, right? It's easy. It's easy to just drink the extra beer. It's easy to ignore to suppress seeing a colleague who's bothering you and just like walk the other way. Avoidance is easier. ignoring is easier, denial is easier, drinking is easier, yelling, screaming is easy, complex problem

solving, meditating, you know, takes effort. Listen to the psychology podcast on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. Don't let biased algorithms or degree screens or exclusive professional networks or stereotypes. Don't let anything keep you from discovering the half of the workforce who are stars. Workers skilled through alternative routes rather than a bachelor's degree. It's time to tear the paper ceiling and see the stars beyond it. Find out how you can make stars part of your talent strategy at tear the paper sealing.org,

brought to you by opportunity at work in the ad council. Okay, we're back and we are talking about the crazy things that happen in our universe, things that happen at light speed, things that happen at super high pressure and temperature. And now we're going to talk about some of the weird things that we see in our universe, specifically in our solar system. Hey, Daniel and Jorge. This is Brendan from St. Louis, Missouri. And I have a question for you guys that I've been thinking about for a little while now

and can only find that we apparently don't know. I'm just wondering if that's really true or what our latest understanding is of what happened to Uranus to make it sideways. And could that have been what gave it its rings or is that just wild speculation? We'd love you guys as input on something like this. All right. Thanks very much for that awesome question. I love Uranus because Uranus is really weird. It's not just that it makes diamonds that rain in the interior. It's a very unusual planet relative to the other planets in our solar system. If you look at the solar system sort of from the top down, the sun is spinning counterclockwise. And you notice that most of the things in the solar system follow that pattern. They move around the sun

counterclockwise and they rotate counterclockwise. And there's a reason for that. That's not an accident. That's conservation of angular momentum at work. You see, all the stuff that made our solar system, the big blob of gas and dust and little particles and flex of gold from previous solar systems, all that stuff when it formed was already spinning. And that spin can't just go away. right? If you start something spinning in space and leave it, it will spin forever. And so if you have a huge cloud of gas and dust, it might be spinning slowly. But then when gravity coalesces it into something smaller and denser, then it needs to spin faster in order to have the same total amount of spin. It's like a figure skater. If she pulls her arms in, she goes faster because she has to have a higher rotation rate to have the same total angular momentum. And so as a huge cloud of slow, slowly spinning gas and dust coalesced into the sun and the planets, that spin couldn't just go away. And that's why we get the planets mostly going around the sun in the same direction that the sun is spinning and also spinning around their axes in that same direction. And that's why it's really interesting and really weird that it's only mostly the case.

Those exceptions are fascinating because they might just reveal crazy stories about what happened in the formation of our society. solar system. And so Uranus in particular is an oddball, quite literally, because it's tilted more than 90 degrees. It's not just on its side. It's on its side plus a little bit. And it spins clockwise instead of counterclockwise. So it really stands out. And because Uranus is not a small thing, right? It's not like one tiny and little rock that happens to be spinning the wrong way. It's an enormous ice giant of a planet. It's got a lot of mass, which means it has a lot of of kinetic energy and a lot of angular momentum. It's not something that happens very easily. And the more you look at Uranus, the more you see that it's weird. I mean, it's not just that

it's tipped over, so it has like vertical rings and vertical moons, but in the summer, its North Pole points towards the sun, right? That makes for really weird seasons. And the definition of North Pole is sort of odd on Uranus also, because it's defined by the axis, but the magnetic poles are not very well lined up with its spin. It has this really weird, off-center magnetic field. And, you know, on most planets, we think the magnetic field is formed by, like, the sloshing around of currents of molten metals, but we don't really know what's going on inside Uranus, and we don't know why that spinning would give you a different magnetic field direction than the

actual spin of the planet. So for a long time, people have thought this must be evidence of some cosmic collision. Why would you think a cosmic collision? Well, the reason is that in order to have something stop spinning or to change its spin, you need something external. You need something to come from outside the solar system, some new source of angular momentum that comes in and can stop the spin or knock the spin or change the spin.

That's why we think about Uranus maybe having such a strange configuration because it got knocked into by some huge thing that came in from outside the solar system. But this thing would have to be huge. Like the calculations, until about a year ago, people were thinking this needed some object like twice the mass of the earth. So again, this is not a little rock that hit Uranus, you know, a little rock like the size of the one that killed the dinosaurs. This is a rock twice the size of the earth that collided into Uranus and knocked it over. At least, that was the theory for a while. But, you know, let that marinate in your head for a minute.

Like, what would that have looked like? If you could have seen that up close, oh my gosh, it would have put Michael Bay and all the Transformer movies to shame. I would have loved to see that sort of real effect in action. Of course, from a safe distance. The problem is that it would have been a very cataclysmic event, and we should see records of it all around the environment of Uranus. But when we look, for example, at the moons of Uranus, we don't see that.

If such an event happened, you would expect, for example, all the ice to be stripped from those moons and to have mostly just like little bits of rock as those moons would have been obliterated. But we don't really see that. And so there's not the evidence of that huge collision, but we still have uranus knocked over on its side. What could have done that other than some weird external source of angular momentum? Well, it could also be a weird interplay, but with the angular momentum inside the solar system, which you can sort of slosh around from object to object. And you might wonder, well, how can that happen without collisions? Well, remember that there's still gravity here and there's lots of different objects sloshing around. Uranus is there and it has

rings and various objects in the solar system can transfer angular momentum back and forth between each other just using gravity. For example, the Earth's moon is slowing down the spin of the Earth as it leaves. It's sort of stealing our angular momentum because of these gravitational interactions. And so recently there's been a new theory for how you Uranus might have gotten its weird direction and weird spin, and it has to do with how Uranus's orbit around the sun interferes and interacts with its spin. And that is that Uranus, like most planets, doesn't orbit the sun in a perfect circle. It orbits it in an ellipse. And an ellipse, unlike a circle, has a preferred direction, like a long axis. Well, that long axis moves around the

sun, and that's called precession. And in a similar way, there's a precession for the spin of the planet. It turns out that those two things can create a resonance, which can actually affect the angle that the planet is tilting at. Sort of like if you think about a gyroscope here on Earth, you can spin a gyroscope and then see it sort of like tilt over. There are all these really complicated dynamics with angular momentum that can get your brain sort of twist it up. But they've done these calculations and they've done these models and they've seen that like a gyroscope effect, if you get Uranus in the right configuration, then it's spin procession and its orbit can interfere in a way that tilts it over. But the funny thing is that in these models for their

calculations, they've only ever gotten a uranist-like planet to tilt over about like 65 or 70 degrees. They can get it to tilt all the way over to 90 degrees just using this trick with the interference of the processions. And so then they added the collision of a smaller object. So it turns out if you tilted over using this gyroscope procession effect and then you toss in a planet just about half the size of Earth instead of twice the size of Earth, then you can knock Uranus over on its side without blasting all the ice from its moons. So that means that if you hit Uranus with an object, half the size of Earth instead of twice the size of Earth, it can survive, it can get the right tilt, and the moons can keep their ice. So, you know, a lot of this is guesswork. We really just don't

know. What we're doing is we're looking at the clues that we see here today in our solar system. and we're trying to explain things that happened maybe billions of years ago. And we're doing these calculations and trying to say, hey, could this be an explanation? So we're building up more and more sophisticated possible explanations for what might explain what we see. That doesn't mean conclusively this is what happened, right? The way science works is you come up with a potential explanation for what you see. And then you ask yourself questions like, what would be unique about this? Or what can I predict?

How else could I test this model? And that's, for example, how people came up with this curiosity of the fact that there is still ice on the moons of Uranus, which is not consistent with having Uranus be impacted by an object twice the mass of the earth. So as you make more refinements, you ask yourself more questions, does this explain this? Could I test it in this other way? You come up with more and more clever ideas for how to test your theory. And if it keeps passing those tests, then you build confidence in this explanation. And if it fails one of them, go back to the drawing board and you come up with a new idea. idea. But hey, that's the process of science. That's why we ask these questions because by asking

them, we learn things and we slowly peel back layers of reality to reveal the true nature of the universe. And so I'm just excited to be on this journey here with you, trying to understand the universe, trying to peel back those layers of reality, trying to get us closer to the ultimate truth about the way the universe actually works. So thanks to everybody who's sent in those questions. and thanks to everybody who engages with us on Twitter at Daniel and Jorge or sends us questions to questions at Danielanhorpe.com. We love hearing from you. We want to answer your questions about the universe. We want to explain the universe to you. So thanks everybody for your attention and your questions and for sharing your curiosity with us. Tune in next time.

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