Speaker 1: Is our corner of the universe weird? For the longest time,
Speaker 1: we thought that Earth was everything. When people used to
Speaker 1: wonder about the nature of the universe, they were mostly
Speaker 1: thinking about the rules for how things worked down here.
Speaker 1: Even the stars just seemed like sort of decorations in
Speaker 1: the sky. Now, of course, we know that there's much
Speaker 1: more out there, And our little slice of this planet
Speaker 1: is the tiniest fraction of the space in the Solar System,
Speaker 1: which is an infinitesimal speck of the volume of the galaxy,
Speaker 1: which of course is the tiniest drop in intergalactic space.
Speaker 1: And the stuff that goes on out there and the
Speaker 1: rest of the universe is super crazy. It's a bonkers
Speaker 1: universe out there, filled with black holes and pulsars and
Speaker 1: giant jets and crazy conditions. So is our corner of
Speaker 1: the universe weird? Or is it the least weird place
Speaker 1: in the cosmos? Hi? I'm Daniel, I'm a particle physicist,
Speaker 1: and I have the weirdest questions about our weird cosmos.
Speaker 1: And welcome to the podcast Daniel and Jorge Explain the Universe,
Speaker 1: a production of I Heart Radio in which we dare
Speaker 1: to ask the biggest questions about the biggest things in
Speaker 1: the universe. We explore the tiniest little particles and ask
Speaker 1: those tiny little questions about what those crazy little quantum
Speaker 1: objects are doing. But mostly we join you in the
Speaker 1: struggle to understand the nature of this universe that we
Speaker 1: find ourselves in. But we marinate in the joy of
Speaker 1: that wonder and that curiosity. We embrace it. We ask
Speaker 1: those questions about the nature of the universe, and we
Speaker 1: dare to demand answers. We're not always satisfied with what
Speaker 1: we find, but we understand it's a process. Science is
Speaker 1: not a list of answers. It's a way of figuring
Speaker 1: out how the universe works. It's daring to expect that
Speaker 1: we can actually understand the way the universe functions, that
Speaker 1: we could hold in our head a model for how
Speaker 1: the universe works and actually makes sense of it. That
Speaker 1: would be an exciting day. That is a day in
Speaker 1: the future. But until then, we can peel it apart,
Speaker 1: one little bit at a time and try to help
Speaker 1: you understand something about the nature of the universe. And
Speaker 1: to do that, we want to encourage you to ask
Speaker 1: your questions, to think deep thoughts about how the universe
Speaker 1: works and to wonder when things don't fit together. And
Speaker 1: so for that reason, we love on this podcast answering
Speaker 1: questions from listeners. And so you probably noticed by now
Speaker 1: is just me here in the studio today, So as usual,
Speaker 1: I'm going to use this opportunity to catch up on
Speaker 1: some listener questions, and so on today's program we have
Speaker 1: listeners questions about diamonds and Jupiter, about chips approaching each
Speaker 1: other near the speed of light, and about what knocked
Speaker 1: Uranus on its side. So thank you to everybody who
Speaker 1: writes in with their questions via Twitter, via email, or
Speaker 1: sends us an audio clip that we can actually use
Speaker 1: on the podcast. If you have questions that you want answered,
Speaker 1: we answer every tweet. We're right back to every email.
Speaker 1: Please send us your questions two questions at Daniel and
Speaker 1: Jorge dot com. We really want to explain the universe
Speaker 1: to you. And if you're too shy to send us questions,
Speaker 1: you can also drop into my public office hours where
Speaker 1: I hang out on zoo and answer physics questions from
Speaker 1: anybody and everybody, including follow up questions and crazy hypotheticals.
Speaker 1: So please come join us if you want connection and
Speaker 1: schedule details about my public office hours. Check out my
Speaker 1: websites at sites dot u, se I, dot edu, slash
Speaker 1: Daniel where you can find all the information. Alright, so
Speaker 1: let's dig into some of these super fun questions from listeners.
Speaker 1: Here's the first one. It's all about diamonds. Hey, Daniel
Speaker 1: and Jorgey. This is Andy and Indiana and I just
Speaker 1: had a hypothetical question for you. Suppose it were possible
Speaker 1: to fly a spaceship up next to Jupiter at the
Speaker 1: very top of its atmosphere, and you tossed a piece
Speaker 1: of coal out the window. Would it turn into a
Speaker 1: diamond before it hit the ground? Thanks guys, I love
Speaker 1: the podcast. All right, So Andy and Indiana doesn't want
Speaker 1: to go to the mall to buy a diamond for
Speaker 1: an engagement ring, and instead wants to fly to Jubiter,
Speaker 1: drop a piece of coal into the atmosphere and see
Speaker 1: if that will turn into a much cheaper diamond. Well,
Speaker 1: I'm not sure that's a good return on investment given
Speaker 1: the expense of getting to Jupiter, but it's a really
Speaker 1: fun question about what actually happens in the crazy intense
Speaker 1: heat and pressure of these gas giants. So let's break
Speaker 1: it down. How do you actually make a diamond, Like,
Speaker 1: how does that happen here on Earth? Could you just
Speaker 1: take a piece of coal and squeeze it really really
Speaker 1: hard and form a diamond. Well, it's true that diamonds
Speaker 1: are just another form of carbon, right, and carbon has
Speaker 1: lots of interesting forms. Coal is mostly carbon, graphite is
Speaker 1: carbon nanotubes or carbon. You can assemble these little bits
Speaker 1: of carbon and lots of different ways that have lots
Speaker 1: of different properties at the macroscopic level. And to me,
Speaker 1: that's super cool that, like the same basic building blocks,
Speaker 1: you can reassemble in different ways and get really very
Speaker 1: different materials. Right. It tells you that there's something deep
Speaker 1: about the arrangement of stuff, That it's the arrangement of
Speaker 1: those carbon molecules that makes a diamond a diamond, and
Speaker 1: a piece of coal a coal, not the thing it's
Speaker 1: made out of. And that's a deeper truth that we've
Speaker 1: learned about the whole Nate you're of the universe, right,
Speaker 1: That it's not what you're made out of, but how
Speaker 1: you're put together. And that's why, for example, you are
Speaker 1: made out of the same particles as eighty ms of
Speaker 1: lava or of hamster. It's all the same stuff, just
Speaker 1: rearranged in another way. And that's the cool thing about diamonds.
Speaker 1: If you start from carbon and you get them under
Speaker 1: really intense heat and pressure we're talking about like two
Speaker 1: thousand degrees fahrenheit, they will form this really interesting structure
Speaker 1: which will then survive when it goes back down to
Speaker 1: lower temperatures. Right, it's not like the diamonds form only
Speaker 1: in that intense heat and pressure and then sort of
Speaker 1: break apart. You form this really intense thing under pressure,
Speaker 1: and then it holds up when it gets back down
Speaker 1: to lower temperatures and lower pressure. And that's the really
Speaker 1: awesome thing. It takes this energy to build it, but
Speaker 1: once it clicks into place, it's super duper strong. Now,
Speaker 1: you don't get diamonds under normal conditions on the surface
Speaker 1: of the Earth. Most of the diamonds that are on
Speaker 1: people's engagement rings walking around come from like a hundred
Speaker 1: and fifty to two hundred kilometers below the surface of
Speaker 1: the Earth. That's where the temperature is high enough and
Speaker 1: the pressure is intense enough to make it. But it
Speaker 1: doesn't come from coal. Right, Most diamonds that we have
Speaker 1: are not in the byproduct of coal. Getting squeezed because
Speaker 1: coal is actually a relatively late addition to the Earth's crust. Remember,
Speaker 1: coal is basically dead plants. Plants form and grow and
Speaker 1: they pull carbon out of the atmosphere, and then they
Speaker 1: die and they get squished down and you get oil
Speaker 1: or carbon. All these fossil fuels are the remnants of
Speaker 1: dead plants. But diamonds have been forming on Earth since
Speaker 1: well before there were even plants, and so the raw
Speaker 1: materials are the same for coal and for diamonds, But
Speaker 1: that doesn't mean that the diamonds we have actually form
Speaker 1: from coal, right And also coal tends to be in
Speaker 1: these sort of horizontal seams. It's laid down in layers,
Speaker 1: whereas diamonds we typically find them in the vertical pipes
Speaker 1: inside the Earth. And the reason is that these diamonds
Speaker 1: are formed deep deep under the Earth's surface two hundred kilometers,
Speaker 1: but for us to find them, they need to somehow
Speaker 1: get up to the surface of the Earth, and that's
Speaker 1: done by volcanoes. So you need these like vertical pipes
Speaker 1: of lava that carry the diamonds up from deep under
Speaker 1: the Earth's surface to near the surface where we can
Speaker 1: find them. In mind, so that's where most of the
Speaker 1: diamonds come from. But there's actually another super cool kind
Speaker 1: of diamond that's made on the Earth's surface, and that's
Speaker 1: an asteroid impact diamond. Remember when our rock hits the Earth,
Speaker 1: usually it burns up in the atmosphere, but if it's
Speaker 1: big enough, it can make it all the way down
Speaker 1: to the surface of the Earth and impact, and if
Speaker 1: it's large enough that can have as much energy is
Speaker 1: like the explosion of a nuclear weapon. Remember the rock
Speaker 1: that killed off the dinosaurs was a really big one.
Speaker 1: It tossed a lot of ash and dust into space,
Speaker 1: blocking out the Sun. So that is definitely capable of
Speaker 1: creating the conditions you would need to form diamonds. You
Speaker 1: get super high temperature when that think impacts, and at
Speaker 1: the impact side you also have really high pressure, which
Speaker 1: means you can form diamonds when they impact. And if
Speaker 1: you go to a meteor creater, this crazy hole in
Speaker 1: the ground in Arizona, you can actually see these things.
Speaker 1: They find these millimeter sized micro diamonds in meteor creater. Alright,
Speaker 1: so what would happen if you actually took a chunk
Speaker 1: of coal and went to Jupiter and dropped it in
Speaker 1: There is Jupiter really capable of forming diamonds, And the
Speaker 1: answer is yes, Jupiter's like a diamond forming factory. Now
Speaker 1: a lot of this is speculation or based on models,
Speaker 1: but we have ideas for what the pressure and temperature
Speaker 1: are in the various layers of Jupiter's atmosphere, and we
Speaker 1: have this from models that we've developed, and then we
Speaker 1: can test them from various probes that have gone to
Speaker 1: visit the planets and gather a little bit of data
Speaker 1: and constrain those model and those models tell us that
Speaker 1: in the interior of Jupiter, you do have the pressure
Speaker 1: and the temperature necessary to make diamonds. And for a
Speaker 1: long time, people thought that it was mostly uranous and
Speaker 1: Neptune that were diamond making factories because they have the
Speaker 1: raw materials you need to make diamonds, that is, methane.
Speaker 1: Methane is a very carbonaceous molecule, and so it has
Speaker 1: those raw materials. But these days we think that Jupiter,
Speaker 1: which has less methane, also has enough to be making diamonds.
Speaker 1: And so what happens is you have this atmospheric methane
Speaker 1: sort of on the higher levels, and then you might get,
Speaker 1: for example, a spark from lightning storms and the surface
Speaker 1: of these planets, and that can spark the formation of
Speaker 1: a diamond, which then drops into the interior and gathers
Speaker 1: more material as it goes until these diamonds, which then
Speaker 1: get heavier, fall deeper and deeper and they grow. And
Speaker 1: nobody actually knows how big these diamonds can get. They
Speaker 1: might just be small, like super tiny nano diamonds and
Speaker 1: you have a whole lot of them. Or it could
Speaker 1: be that they accumulate like hail falling in the Earth's atmosphere,
Speaker 1: gathering up more and more water. You could even get
Speaker 1: these like massive diamond bergs they call them, forming in
Speaker 1: the interior of Jupiter. The only way to really figure
Speaker 1: that out is to go into probe it, but we
Speaker 1: haven't had a chance to do that yet. So we
Speaker 1: think that the conditions are right for Saturn and Jupiter
Speaker 1: to form diamonds, to have this essentially constant rain of diamonds,
Speaker 1: and according to calculations, there were produced tons and tons
Speaker 1: of diamonds every year, so they anticipate there are something
Speaker 1: like ten million tons of diamonds on Saturn and Jupiter.
Speaker 1: So if you could get a probe out there, you
Speaker 1: wouldn't need to bring your own coal. There are already
Speaker 1: tons of diamonds in jubiter But the question was about
Speaker 1: whether it would form a diamond before it hit the ground. Remember,
Speaker 1: the definition of the ground or the surface of Jupiter
Speaker 1: is a bit fuzzy. There is a rocky, icy core,
Speaker 1: but things get really dense before you even get there,
Speaker 1: and so a bit of coal that turns into diamond
Speaker 1: would probably stop well before it reached that rocky icy core.
Speaker 1: It would stop when it hits the point where it's
Speaker 1: equilibrated right whereas the same density as the stuff that's
Speaker 1: around it. And we don't actually know what would happen
Speaker 1: to these things as they drop into the core of Jupiter,
Speaker 1: because on Jupiter specifically, the conditions are so extreme that
Speaker 1: it might be possible that these diamonds form liquids. These
Speaker 1: diamonds get so compressed that you get like liquid diamond
Speaker 1: oceans on Jupiter. We think on Urineus and Neptune, to contrast,
Speaker 1: that the temperatures are much cooler and you don't reach
Speaker 1: that like eight thousand kelvin degrees you need to melt diamonds.
Speaker 1: So Urine is a Neptune probably have huge collections of
Speaker 1: diamonds in their interior, but on Jupiter those diamonds may
Speaker 1: have melted and contributed to these vast oceans of liquid
Speaker 1: diamond It's fascinating. We still don't know really what's going
Speaker 1: on inside Jupiter. We know it's crazy. We know that
Speaker 1: it's very different from what's going on here on Earth,
Speaker 1: which makes it hard to extrapolate and hard to measure.
Speaker 1: But until we get more probes out there dropping coal
Speaker 1: or just dropping instruments into the atmosphere of Jupiter, then
Speaker 1: we won't really know what's going on. But it's a
Speaker 1: fascinating place to learn about what materials can do. You know,
Speaker 1: it's all the same basic elements, just playing different roles,
Speaker 1: just fitting together in different ways, and in some cases
Speaker 1: you need special conditions in order to make them. But
Speaker 1: the amazing thing is that they last even after those
Speaker 1: conditions have broken, even when they get pulled out into
Speaker 1: lower temperature and pressure conditions, we still have these literal
Speaker 1: crystals of knowledge that come out of those situations. So
Speaker 1: thanks Andy from Indiana for asking a fun question about
Speaker 1: dropping coal into the atmosphere of Jupiter. I want to
Speaker 1: answer a couple more questions, but first, let's take a
Speaker 1: quick break. All right, we are back and we are
Speaker 1: talking about the crazy things that go on in our
Speaker 1: universe and answering listener questions about the extreme conditions that
Speaker 1: we find in our solar system and out in deep space.
Speaker 1: So here we have another fun hypothetical question from Cole. Hello,
Speaker 1: Daniel and Jorge. This is Cole Packard and I'm from Reading, California.
Speaker 1: I'm a big fan of the podcast and I love
Speaker 1: listening to you guys. While I'm driving, I was listening
Speaker 1: to your episode about how special relativity affects how we
Speaker 1: perceived time, and it got me thinking, what if two
Speaker 1: observers were traveling towards each other, both going near the
Speaker 1: speed of light, would their relative philosophies be close to
Speaker 1: twice the speed of light? Would the time distortion make
Speaker 1: each observer look extremely slow to the other. Looking forward
Speaker 1: to hearing your answers. Thank you all right, Thanks very
Speaker 1: much Cole for asking a question about one of my
Speaker 1: favorite topics, which is the crazy bonkers nature of our
Speaker 1: universe at high velocity. Because we here on Earth are
Speaker 1: used to things moving pretty slow, and we developed an
Speaker 1: intuition that tells us what happens when you throw a baseball.
Speaker 1: How fast is that baseball moving relative to the ground.
Speaker 1: And it turns out that intuition is just flat wrong.
Speaker 1: I mean, it mostly works if things are moving slow,
Speaker 1: but it turns out the rules are actually fundamentally different,
Speaker 1: and that only when you get to very high velocities,
Speaker 1: velocities approaching the speed of light, do you see that
Speaker 1: intuition breaking down and reveal the true nature of the universe.
Speaker 1: But this is one of my favorite examples. This is
Speaker 1: why we push ourselves to understand the extreme situations of
Speaker 1: the universe, because it's there that the truth is revealed.
Speaker 1: And we don't want just an intuitive understanding of the
Speaker 1: universe that's sort of kind of works. We want to
Speaker 1: know the truth. We want to read the fundamental truth
Speaker 1: of the universe. We want to reveal its source code.
Speaker 1: We want to understand how the universe actually works, not
Speaker 1: just some approximation that kind of works in some situations.
Speaker 1: So that's why I love special relativity and examples like
Speaker 1: this that make us try to understand how things work
Speaker 1: in crazy conditions. Now, Cole was asking us a fun
Speaker 1: question about what happens when two ships approach each other
Speaker 1: each moving close to the speed of light, and also
Speaker 1: what happens to the clocks on those ships. So Cole
Speaker 1: has managed to touch on basically all the critical elements
Speaker 1: of special relativity. So to answer this question, we're gonna
Speaker 1: need to remember a few things. First, remember that all
Speaker 1: speeds are measured as relative speeds. You can't talk about
Speaker 1: a spaceship moving near the speed of light. You have
Speaker 1: to say moving near the speed of light as measured
Speaker 1: by who, or moving near the speed of light relative
Speaker 1: to what. Because there are no absolute measures, there's no
Speaker 1: like reference frame floating out there in space that can
Speaker 1: measure the speed of a ship. You always have to
Speaker 1: say the speed relative to what. And it's especially important
Speaker 1: and special relativity because two different observers moving in different
Speaker 1: speeds will see the same ship and report different results.
Speaker 1: The thing we have to remember, number two, is that
Speaker 1: we can't simply add velocities. You know, if you are
Speaker 1: in a car moving at twenty miles an hour relative
Speaker 1: to the ground, and you throw a baseball at twenty
Speaker 1: miles an hour, how fast is that baseball moving a
Speaker 1: relative to the ground. Well, you think, oh, that's easy.
Speaker 1: It's twenty miles an hour from the car plus twenty
Speaker 1: miles an hour from your arm, you have forty miles
Speaker 1: an hour. And that's true for small velocities. But because
Speaker 1: in special relativity nothing can go faster than the speed
Speaker 1: of light, you've got to change that rule. And it
Speaker 1: turns out that as you get too high velocities, you
Speaker 1: can't just add those velocities in a simple way. The
Speaker 1: velocity is added in a really weird, nonlinear way, and
Speaker 1: that's one thing that prevents you from going faster than
Speaker 1: the speed of light. So, for example, if you are
Speaker 1: in a spaceship flying at seven tenths the speed of
Speaker 1: light relative to the Earth, and you throw a baseball
Speaker 1: with your amazing arm at seven tenths of the speed
Speaker 1: of light in the same direction, do we measure that
Speaker 1: baseball going at point seven plus point seven or one
Speaker 1: point four times the speed of light. No, we don't,
Speaker 1: because you can't just add those velocities. Instead, you get
Speaker 1: something like zero point nine five times the speed of light.
Speaker 1: Things don't just add up linearly, and that's another thing
Speaker 1: that's going to make it really weird to observe the
Speaker 1: same events at different velocity. And the last thing we
Speaker 1: need to understand to answer Cole's question is how time
Speaker 1: is affected by special relativity. And the thing to understand
Speaker 1: there is that moving clocks run slowly. If you see
Speaker 1: a clock that's moving away from you really, really fast,
Speaker 1: you will observe it's time running slowly, all right. So
Speaker 1: with that in mind, let's dig into Cole's question. Cole says,
Speaker 1: what happens if these two ships are approaching each other
Speaker 1: and both are moving near the speed of light. So
Speaker 1: first let's clarify if both are moving near the speed
Speaker 1: of light, who is measuring that speed? So let's put
Speaker 1: Earth at the center of that and say that one
Speaker 1: ship is coming at Earth near the speed of light,
Speaker 1: and the other ship is coming at Earth from the
Speaker 1: other direction, also near the speed of light. So we're
Speaker 1: on Earth and we measure ship one coming at us
Speaker 1: near the speed of light from Mars, for example, and
Speaker 1: the other one is coming the other direction and also
Speaker 1: near the speed of light. Now you look at those
Speaker 1: two ships and you ask yourself how fast are they
Speaker 1: moving relative to each other? If these velocities were very
Speaker 1: very slow, we were on the surface of the Earth
Speaker 1: and you had, for example, two cars both coming at
Speaker 1: you at twenty miles an hour, you could say, oh,
Speaker 1: the cars are approaching each other at forty miles an hour,
Speaker 1: but zoom back out to space. If both ships are
Speaker 1: approaching you at seven tenths the speed of light, you
Speaker 1: can't say that they are approaching each other at one
Speaker 1: point four times the speed of light because the velocity
Speaker 1: addition is not linear. Instead, on each ship they could
Speaker 1: measure the speed of the other ship and they would
Speaker 1: see something like of the speed of light, and that
Speaker 1: works for both ships because the situation is symmetric. So
Speaker 1: on Earth we measure each ship as coming towards us
Speaker 1: at like seven tenths the speed of light, but each
Speaker 1: ship doesn't measure the other one is traveling faster than
Speaker 1: the speed of light. Because you can't just add the
Speaker 1: velocities linear, we have this crazy non linear velocity addition
Speaker 1: rule which changes things. Now here's a bit of a
Speaker 1: brain twisty part. The distance between the two ships, as
Speaker 1: seen from Earth is decreasing as faster than the speed
Speaker 1: of light. That is, from Earth, both ships are moving
Speaker 1: it less than the speed of light. But if you
Speaker 1: measure the distance between the ships from Earth, that number
Speaker 1: is decreasing faster than light could move between the two ships, right,
Speaker 1: Because that's just measuring the distance between the two ships,
Speaker 1: and we see one ship going in one direction is
Speaker 1: seven tenths of speed of light and the other one
Speaker 1: going in the other direction at seven tenths of speed
Speaker 1: of light. So we see the distance between them decreasing
Speaker 1: at faster than the speed of light. And that's okay,
Speaker 1: because nobody in the scenario is moving faster than the
Speaker 1: speed of light relative to anybody else, because if you
Speaker 1: transform to the frame of one ship, they only see
Speaker 1: that distance decreasing at the speed of light. And that's
Speaker 1: the crazy thing is that different people can see the
Speaker 1: same events and report different answers and everybody can be correct. Right.
Speaker 1: We can give different conflicting reports of the same scenario
Speaker 1: and all be correct. That's the most crazy thing about
Speaker 1: the universe I've ever learned about in physics, that there
Speaker 1: isn't one true history of the universe that we could
Speaker 1: all agree on, that if we all had accurate clocks
Speaker 1: and devices and rulers, then we could all figure out,
Speaker 1: like what really happened? There is no what really happened
Speaker 1: for the whole universe. There's a what really happened? If
Speaker 1: you were at this location and moving at this velocity.
Speaker 1: Then there's another what really happened if you were over
Speaker 1: there moving at that velocity. And the crazy thing is
Speaker 1: that they do not have to agree and they can
Speaker 1: all be correct. We talked about this in our episode
Speaker 1: about time dilation. For example, different people might have different
Speaker 1: stories to tell about who won a race, and that's
Speaker 1: because the definition of now. But whether two things happen
Speaker 1: at the same moment also depends on where you are
Speaker 1: and how fast you're moving. And that leads us to
Speaker 1: the second part of Cole's awesome question about time. You see,
Speaker 1: we know that moving clocks run slowly. That means that
Speaker 1: if you see a clock moving at high velocity relative
Speaker 1: to you, you will see that clock's time running slowly.
Speaker 1: So say both of these ships which are approaching Earth
Speaker 1: at seven tenths of speed of light in opposite directions.
Speaker 1: Both of these ships have a clock on them, and
Speaker 1: they have awesome telescopes so that the people on the
Speaker 1: ships can read their own clocks and they can also
Speaker 1: peer through these super telescopes to read the clock on
Speaker 1: the other ship. So you're on a ship, you're moving
Speaker 1: at seven tenths to speed of light. Most people make
Speaker 1: the mistake of thinking that you will feel time and
Speaker 1: running slow. You won't. You always feel your time running
Speaker 1: the same way, running at one second per second. And
Speaker 1: if you look down at the clock in your hand,
Speaker 1: you will see it running normally. Why is that? Doesn't
Speaker 1: time move slow at high speeds? It does, but it
Speaker 1: only slows down for moving clocks, And your clock, which
Speaker 1: is in your hand, is not moving relative to you.
Speaker 1: You are not moving relative to you. And that's why
Speaker 1: time passes normally for you. Now, if you look through
Speaker 1: your telescope and you look at the clock on the
Speaker 1: other ship, you see that clock moving really really fast,
Speaker 1: coming towards you at of the speed of light. And
Speaker 1: so you see that clock running slowly. You think, for
Speaker 1: every ten seconds that passes on your clock, you only
Speaker 1: see one second tick on that clock. So that's really weird, right,
Speaker 1: is time passing differently on that ship? No, you can't
Speaker 1: make statements about that. You can only make statements about
Speaker 1: what you observe. Because now flip it around and put
Speaker 1: yourself on the other ship. Right that other ship, they
Speaker 1: see their clock running normally. They don't see their clock
Speaker 1: running slowly the way you see it. They see their
Speaker 1: clock running normally, and when they look through their telescope
Speaker 1: they see your clock running slowly. It's another example of
Speaker 1: how two people to observers can give faithful accounts but
Speaker 1: come up with different stories about what happens. You say
Speaker 1: their clock is running slowly, they say your clock is
Speaker 1: running slowly. The physics part of your brain says, what
Speaker 1: what actually is happening? And the answer is, there are
Speaker 1: different things happening based on where you are and how
Speaker 1: fast you are going, right, because truth and history are
Speaker 1: not absolute anymore. They are relative, and they are a
Speaker 1: function of location and velocity. And you might think to yourself,
Speaker 1: how can that possibly be the reality? How can our
Speaker 1: universe actually work that way? Doesn't it lead to all
Speaker 1: sorts of contradictions. Well, you know, all these effects happen
Speaker 1: when people are far apart or moving relative to each
Speaker 1: other at very high speeds, and so it makes it
Speaker 1: hard to spot these things. And you just have an
Speaker 1: intuition that the universe works in a certain way, that
Speaker 1: there's like a universe clock that ticks forward, and the
Speaker 1: universe has sort of a state right now, and then
Speaker 1: it takes forward and has another state, sort of like
Speaker 1: a universal movie that's sliding forward in time. But that's
Speaker 1: just not the situation. What we've revealed to our experiments
Speaker 1: is that things really do depend on where you are
Speaker 1: and how fast you are going. That there is really
Speaker 1: no absolute truth to what happens in the universe. Alright, cold,
Speaker 1: thanks very much for asking that super fun question. I
Speaker 1: want to get to one more question, but first let's
Speaker 1: take another break. Okay, we're back, and we are talking
Speaker 1: about the crazy things that happened in our universe, things
Speaker 1: that happened at light speed, things that happened it's super
Speaker 1: high pressure and temperature, and now we're going to talk
Speaker 1: about some of the weird things that we see in
Speaker 1: our universe, specifically in our solar system. Hey, Daniel and Jorge,
Speaker 1: this is Brendon from St. Louis, Missouri, and I have
Speaker 1: a question for you guys that I've been thinking about
Speaker 1: for a little while. Now. You can only find that
Speaker 1: we apparently don't know. I'm just wondering if that's really
Speaker 1: true or what our latest understanding is of what happened
Speaker 1: to uriness to make it sideways and could that have
Speaker 1: been what gave it its rings or is that just
Speaker 1: wild speculation? Would love you guys, input on something like this.
Speaker 1: All right, thanks very much for that awesome question. I
Speaker 1: love Urinus because Urinus is really weird. It's not just
Speaker 1: that it makes diamonds that rain in the interior. It's
Speaker 1: a very unusual planet relative to the other planets in
Speaker 1: our solar system. Right, if you look at the Solar
Speaker 1: system sort of from the top down, the Sun is
Speaker 1: spinning counter clock wise, and you notice that most of
Speaker 1: the things in the Solar system follow that pattern. They
Speaker 1: move around the Sun counterclockwise, and they rotate counterclockwise. And
Speaker 1: there's a reason for that. That's not an accident. That's
Speaker 1: conservation of angular momentum at work. You see all the
Speaker 1: stuff that made our Solar system, the big blob of
Speaker 1: gas and dust and little particles and flex of gold
Speaker 1: from previous solar systems. All that stuff, when it formed,
Speaker 1: was already spinning. And that spin can't just go away, right.
Speaker 1: If you start something spinning in space and leave it,
Speaker 1: it will spin forever. And so if you have a
Speaker 1: huge cloud of gas and dust, it might be spinning slowly,
Speaker 1: but then when gravity coalesces it into something smaller and
Speaker 1: denser than it needs to spin faster in order to
Speaker 1: have the same total amount of spin. It's like a
Speaker 1: figure skater. If she pulls her arms in, she goes
Speaker 1: faster because she has to have a higher rotation rate
Speaker 1: to have the same total angular momentum. And so as
Speaker 1: that huge cloud of slowly spinning gas and dust coalesced
Speaker 1: into the Sun and the planets, that spin couldn't just
Speaker 1: go away. And that's why we get the planets mostly
Speaker 1: going around the Sun in the same direction that the
Speaker 1: Sun is spinning, and also spinning around their axes in
Speaker 1: that same direction. And that's why it's really interesting and
Speaker 1: really weird that it's only mostly the case. Those exceptions
Speaker 1: are fascinating because they might just reveal crazy stories about
Speaker 1: what happened in the formation of our solar system. And
Speaker 1: so urine is in particular is an odd ball, quite literally,
Speaker 1: because it's tilted more than ninety degrees. It's not just
Speaker 1: on its side, it's on its side plus a little bit,
Speaker 1: and it spins clockwise instead of counterclockwise, so it really
Speaker 1: stands out. And because urine is is not a small thing, right,
Speaker 1: it's not like one tiny little rock that happens to
Speaker 1: be spinning the wrong way. It's an enormous ice giant
Speaker 1: of a planet. It's got a lot of mass, which
Speaker 1: means it has a lot of kinetic energy and a
Speaker 1: lot of angular momentum. It's not something that happens very easily.
Speaker 1: And the more you look at Uranus, the more you
Speaker 1: see that it's weird. I mean, it's not just that
Speaker 1: it's tipped over, so it has like vertical rings and
Speaker 1: vertical moons. But in the summer, it's north pole points
Speaker 1: towards the sun right. That makes really weird seasons, and
Speaker 1: the definition of north pole is sort of odd on
Speaker 1: Urinus also because it's defined by the axis. But the
Speaker 1: magnetic poles are not very well lined up with its spin.
Speaker 1: It has this really weird off center magnetic field. And
Speaker 1: you know, on most planets we think the magnetic field
Speaker 1: is formed by like the slashing around of currents of
Speaker 1: molten metals, but we don't really know what's going on
Speaker 1: inside Uranus, and we don't know why that spinning would
Speaker 1: give you a different magnetic field direction than the actual
Speaker 1: spin of the planet. So for a long time people
Speaker 1: have thought this must be evidence of some cosmic collision.
Speaker 1: Why would you think a cosmic collision, Well, the reason
Speaker 1: is that in order to have something stop spinning or
Speaker 1: to change its spin, you need something external. You need
Speaker 1: something to come from outside the solar system, some new
Speaker 1: source of angular momentum that comes in and can stop
Speaker 1: the spin or knock the spin, or change the spin.
Speaker 1: That's why we think about Uriness maybe having such a
Speaker 1: strange configuration because it got knocked into by some huge
Speaker 1: thing that came in from outside the solar system. But
Speaker 1: this thing would have to be huge, like the calculations.
Speaker 1: Until about a year ago, people were thinking this needed
Speaker 1: some object like twice the mass of the Earth. So again,
Speaker 1: this is not a little rock that hit Urin. It's
Speaker 1: you know, a little rock like the size of the
Speaker 1: one that killed the dinosaurs. This is a rock twice
Speaker 1: the size of the Earth that collided into Urinus and
Speaker 1: knocked it over. At least that was the theory for
Speaker 1: a while. But you know, let that marinate in your
Speaker 1: head for a minute, Like, what would that have looked
Speaker 1: like if you could have seen that up close? Oh
Speaker 1: my gosh, it would have put Michael Bay and all
Speaker 1: the Transformer movie to shame. I would have loved to
Speaker 1: see that sort of real effect in action. Of course,
Speaker 1: from a safe distance. The problem is that it would
Speaker 1: have been a very cataclysmic event, and we should see
Speaker 1: records of it all around the environment of urine is.
Speaker 1: But when we look, for example, at the moons if
Speaker 1: urine is, we don't see that. If such an event happened,
Speaker 1: you would expect, for example, all the ice to be
Speaker 1: stripped from those moons and to have mostly just like
Speaker 1: little bits of rock, as those moons would have been obliterated.
Speaker 1: But we don't really see that, and so there's not
Speaker 1: the evidence of that huge collision. But we still have
Speaker 1: urine Is knocked over on its side. What could have
Speaker 1: done that other than some weird external source of angular momentum, Well,
Speaker 1: it could also be a weird interplay. But with the
Speaker 1: angular momentum inside the Solar System, which you can sort
Speaker 1: of slash around from object to object, and you might wonder, well,
Speaker 1: how can that happen without collisions? Will remember that there's
Speaker 1: still gravity here, and there's lots of different objects slashing around.
Speaker 1: Urinus is there, and it has rings and very barious
Speaker 1: objects in the Solar System can transfer angular momentum back
Speaker 1: and forth between each other just using gravity. For example,
Speaker 1: the Earth's moon is slowing down the spin of the
Speaker 1: Earth as it leaves, it's sort of stealing our angular
Speaker 1: momentum because of these gravitational interactions. And so recently there's
Speaker 1: been a new theory for how Urinus might have gotten
Speaker 1: its weird direction and weird spin, and it has to
Speaker 1: do with how Urinus is orbit around the Sun interferes
Speaker 1: and interacts with its spin. And that is that Uranus,
Speaker 1: like most planets, doesn't orbit the Sun in a perfect circle.
Speaker 1: It orbits it and an ellipse, and an ellipse, un
Speaker 1: like a circle, has a preferred direction that a long axis, well,
Speaker 1: that long axis moves around the Sun, and that's called precession.
Speaker 1: In a similar way, there's a precession for the spin
Speaker 1: of the planet. It turns out that those two things
Speaker 1: can create a resonance which can actually affect the angle
Speaker 1: that the planet is tilting at, sort of like if
Speaker 1: you think about a gyroscope here on Earth. You can
Speaker 1: spin a gyr scope and then see it's sort of
Speaker 1: like tilt over. They're all these really complicated dynamics with
Speaker 1: angular momentum that can get your brains would twisted up.
Speaker 1: But they have done these calculations and they've done these models,
Speaker 1: and they've seen that like a gyroscope effect. If you
Speaker 1: get Uriness in the right configuration, then it's spin procession
Speaker 1: and it's orbit can interfere in a way that tilts
Speaker 1: it over. But the funny thing is that in these
Speaker 1: models for their calculations, they've only ever gotten the urine
Speaker 1: is like planet to tilt over about like sixty five
Speaker 1: or seventy degrees. They can't get into tilt all the
Speaker 1: way over to ninety degrees just using this trick with
Speaker 1: the interference of the processions. And so then they added
Speaker 1: the collision of a smaller object. So it turns out
Speaker 1: if you tilted over using this gyroscope procession effect, and
Speaker 1: then you toss in a planet just about half the
Speaker 1: size of Earth instead of twice the size of Earth,
Speaker 1: then you can knock Uriness over on its side without
Speaker 1: blasting all the ice from its moons. So that means
Speaker 1: that if you hit Urinus with an object half the
Speaker 1: size of Earth instead of twice the size of Earth,
Speaker 1: it can survive. It can get the right tilt, and
Speaker 1: the moons can keep their ice. So you know, a
Speaker 1: lot of this is guesswork. We really just don't know
Speaker 1: what we're doing. Is we're looking at the clues that
Speaker 1: we see here today in our solar system, and we're
Speaker 1: trying to explain things that happen maybe billions of years ago,
Speaker 1: and we're doing these calculations and try to say, hey,
Speaker 1: could this be an explanation? So we're building up more
Speaker 1: and more sophisticated possible explanations for what might explain what
Speaker 1: we see. That doesn't mean conclusively this is what happened,
Speaker 1: right the way science work, Since you come up with
Speaker 1: a potential explanation for what you see, and then you
Speaker 1: ask yourself questions like what would be unique about this
Speaker 1: or what can I predict? How else could I test
Speaker 1: this model? And that's, for example, how people came up
Speaker 1: with this curiosity of the fact that there is still
Speaker 1: ice on the moons of Uranus, which is not consistent
Speaker 1: with having Urinus be impacted by an object twice the
Speaker 1: mass of the Earth. So as you make more refinements,
Speaker 1: you ask yourself more questions, as this explain this be?
Speaker 1: Could I test it in this other way? You come
Speaker 1: up with more and more clever ideas for how to
Speaker 1: test your theory, and if he keeps passing those tests,
Speaker 1: then you build confidence in this explanation and if it fails,
Speaker 1: one of them go back to the drawing board and
Speaker 1: you come up with a new idea. But hey, that's
Speaker 1: the process of science. That's why we ask these questions,
Speaker 1: because by asking them, we learn things, and we slowly
Speaker 1: peel back layers of reality to reveal the true nature
Speaker 1: of the universe. And so I'm just excited to be
Speaker 1: on this journey here with you, trying to understand the universe,
Speaker 1: trying to peel back those layers of reality, trying to
Speaker 1: get us closer to the ultimate truth about the way
Speaker 1: the universe actually works. So thanks to everybody who's sent
Speaker 1: in those questions, and thanks to everybody who engages with
Speaker 1: us on Twitter at Daniel and Jorge or sends us
Speaker 1: questions to questions at Daniel and Jorge dot com. We
Speaker 1: love hearing from you. We want to answer your questions
Speaker 1: about the universe. We want to explain the universe to you.
Speaker 1: So thanks everybody for your attention and your questions and
Speaker 1: for sharing your curiosity with us. Tune in next time.
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explained
Speaker 1: the Universe is a production of I Heart Radio. For
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