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Speaker 1 (00:08):
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 seemed like sort of decorations in
the sky. Now, of course, we know that there's much
(00:32):
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 the tiniest drop in intergalactic space.
And the stuff that goes on out there and the
rest of the universe is super crazy. It's a bonkers
(00:55):
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,
(01:26):
and I have the weirdest questions about our weird cosmos.
And welcome to the podcast Daniel and Jorge Explain the Universe,
a production of I Heart Radio 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
(01:50):
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
(02:13):
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,
(02:34):
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 noticed by now
(02:57):
is 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 and Jupiter, about chips approaching each
other near the speed of light, and about what knocked
(03:20):
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 want answered,
we answer every tweet. We're right back to every email.
Please send us your questions two questions at Daniel and
(03:41):
Jorge dot 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 zoo 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
(04:02):
schedule details about my public office hours. Check out my
websites at sites dot u, se I, dot edu, slash
Daniel where you can find all the information. Alright, 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 Jorgey. This is Andy and Indiana and I just
(04:24):
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 mall to buy a diamond for
an engagement ring, and instead wants to fly to Jubiter,
(04:47):
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,
(05:10):
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 or carbon. You can assemble these little bits
of carbon and lots of different ways that have lots
(05:32):
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
different materials. Right. It tells you that there's something deep
about the arrangement of stuff, That it's the arrangement of
those carbon molecules that makes a diamond a diamond, and
(05:53):
a piece of coal a coal, not the thing it's
made out of. And that's a deeper truth that we've
learned about the whole Nate you're 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 eighty ms of
lava or of hamster. It's all the same stuff, just
(06:14):
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 two
thousand 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
(06:35):
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. And 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
(06:56):
of the Earth. Most of the diamonds that are on
people's engagement rings walking around come from like a hundred
and fifty to two hundred 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 in the byproduct of coal. Getting squeezed because
(07:19):
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
dead plants. But diamonds have been forming on Earth since
(07:40):
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 the vertical pipes
(08:01):
inside the Earth. And the reason is that these diamonds
are formed deep deep under the Earth's surface two hundred 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
(08:23):
find them. In mind, 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 our 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
(08:45):
it's large enough that can have as much energy is
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 is definitely capable of
creating the conditions you would need to form diamonds. You
(09:05):
get super high temperature when that think 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 a meteor creater, this crazy hole in
the ground in Arizona, you can actually see these things.
They find these millimeter sized micro diamonds in meteor creater. Alright,
(09:28):
so what would happen if you actually took a chunk
of coal and went to Jupiter and dropped it 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
(09:51):
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 model 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 uranous and
(10:12):
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
(10:32):
sort of on 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 until these diamonds, which then
get heavier, fall deeper and deeper and they grow. And
nobody actually knows how big these diamonds can get. They
(10:56):
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 into probe it, but we
(11:17):
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, there were produced tons and tons
of diamonds every year, so they anticipate there are something
like ten million tons of diamonds on Saturn and Jupiter.
(11:42):
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 jubiter 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 bit fuzzy. There is a rocky, icy core,
but things get really dense before you even get there,
(12:05):
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 the point where it's
equilibrated right whereas 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
(12:27):
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 Urineus and Neptune, to contrast,
that the temperatures are much cooler and you don't reach
that like eight thousand kelvin degrees you need to melt diamonds.
So Urine is a Neptune probably have huge collections of
(12:50):
diamonds in their interior, but on Jupiter those diamonds may
have melted and contributed to these vast oceans of liquid
diamond It's fascinating. 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.
(13:11):
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
(13:32):
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
(13:54):
answer a couple more questions, but first, let's take a
quick break. All right, we are back and we are
talking about the crazy things that go on in our
(14:15):
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
(14:35):
to your episode about how special relativity affects how we
perceived 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 philosophies 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
(14:58):
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.
(15:21):
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
(15:44):
the universe, because it's there that the truth is revealed.
And we don't want just an intuitive understanding of the
universe that's 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.
(16:07):
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 Cole
has managed to touch on basically all the critical elements
(16:29):
of special relativity. So to answer this question, we're gonna
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
(16:52):
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
and special relativity because two different observers moving in 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
(17:14):
in a car moving at twenty miles an hour relative
to the ground, and you throw a baseball at twenty
miles an hour, how fast is that baseball moving a
relative to the ground. Well, you think, oh, that's easy.
It's twenty miles an hour from the car plus twenty
miles an hour from your arm, you have forty miles
an hour. And that's true for small velocities. But because
(17:35):
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
velocity is added 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
(17:56):
in a spaceship flying at seven tenths the speed of
light relative to the Earth, and you throw a baseball
with your amazing arm at seven tenths of the speed
of light in the same direction, do we measure that
baseball going at point seven plus point seven or one
point four times the speed of light. No, we don't,
(18:16):
because you can't just add those velocities. Instead, you get
something like zero point nine five 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
(18:37):
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 it's time running slowly, all right. So
with that in mind, let's dig into Cole's question. Cole says,
what happens if these two ships are approaching each other
(18:59):
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
(19:21):
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 twenty miles an hour, you could say, oh,
(19:43):
the cars are approaching each other at forty miles an hour,
but zoom back out to space. If both ships are
approaching you at seven tenths the speed of light, you
can't say that they are approaching each other at one
point four times the speed of light because the velocity
addition is not linear. Instead, on each ship they could
(20:03):
measure the speed of the other ship and they would
see something like 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 seven tenths the speed of light, but each
ship doesn't measure the other one is traveling faster than
the speed of light. Because you can't just add the
(20:25):
velocities linear, we have this crazy non linear 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 as faster than the speed
of light. That is, from Earth, both ships are moving
it less than the speed of light. But if you
(20:46):
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 is
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
(21:06):
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 the speed of light. And that's
the crazy thing is that different people can see the
(21:26):
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 could
(21:47):
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
(22:09):
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. But whether two things happen
at the same moment also depends on where you are
and how fast you're moving. And that leads us to
(22:30):
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 seven tenths of speed of light in opposite directions.
(22:51):
Both of these ships have a clock on them, and
they have awesome telescopes so that the people on the
ships 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 seven tenths to speed of light. Most people make
the mistake of thinking that you will feel time and
running slow. You won't. You always feel your time running
(23:13):
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
(23:35):
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 of the speed of light. And
so you see that clock running slowly. You think, for
every ten seconds that passes on your clock, you only
see one second tick on that clock. So that's really weird, right,
(23:57):
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 through their telescope
(24:19):
they see your clock running slowly. It's another example of
how two people to 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
(24:40):
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
(25:02):
sorts of contradictions. Well, you know, all 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
(25:23):
it takes 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 to 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. Alright, cold,
(25:43):
thanks very much for asking that super fun question. I
want to get to one more question, but first let's
take another break. Okay, we're back, and we are talking
(26:03):
about the crazy things that happened in our universe, things
that happened at light speed, things that happened it's 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 Brendon from St. Louis, Missouri, and I have
a question for you guys that I've been thinking about
(26:24):
for a little while. Now. You 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 uriness to make it sideways and could that have
been what gave it its rings or is that just
wild speculation? Would love you guys, input on something like this.
All right, thanks very much for that awesome question. I
love Urinus because Urinus is really weird. It's not just
(26:46):
that it makes diamonds that rain in the interior. It's
a very unusual planet relative to the other planets in
our solar system. Right, if you look at the Solar
system sort of from the top down, the Sun is
spinning counter clock wise, 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
(27:09):
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.
(27:29):
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 than 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
(27:50):
faster because she has to have a higher rotation rate
to have the same total angular momentum. And so as
that huge cloud of 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
(28:10):
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 solar system. And
so urine is in particular is an odd ball, quite literally,
(28:33):
because it's tilted more than ninety 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 urine is is not a small thing, right,
it's not like one tiny little rock that happens to
be spinning the wrong way. It's an enormous ice giant
(28:55):
of a planet. It's got a lot of mass, which
means it has a lot 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, it's north pole points
(29:15):
towards the sun right. That makes really weird seasons, and
the definition of north pole is sort of odd on
Urinus 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
(29:36):
is formed by like the slashing 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
(29:59):
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 Uriness maybe having such a
strange configuration because it got knocked into by some huge
(30:22):
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 Urin. It's
you know, a little rock like the size of the
one that killed the dinosaurs. This is a rock twice
(30:42):
the size of the Earth that collided into Urinus 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 movie to shame. I would have loved to
see that sort of real effect in action. Of course,
(31:05):
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 urine is.
But when we look, for example, at the moons if
urine is, 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.
(31:27):
But we don't really see that, and so there's not
the evidence of that huge collision. But we still have
urine Is 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 slash around from object to object, and you might wonder, well,
(31:51):
how can that happen without collisions? Will remember that there's
still gravity here, and there's lots of different objects slashing around.
Urinus is there, and it has rings and very barious
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
(32:13):
momentum because of these gravitational interactions. And so recently there's
been a new theory for how Urinus might have gotten
its weird direction and weird spin, and it has to
do with how Urinus is 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.
(32:35):
It orbits it and an ellipse, and an ellipse, un
like a circle, has a preferred direction that a long axis, well,
that long axis moves around the Sun, and that's called precession.
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
(32:56):
you think about a gyroscope here on Earth. You can
spin a gyr scope and then see it's sort of
like tilt over. They're all these really complicated dynamics with
angular momentum that can get your brains would twisted up.
But they have done these calculations and they've done these models,
and they've seen that like a gyroscope effect. If you
get Uriness in the right configuration, then it's spin procession
and it's orbit can interfere in a way that tilts
(33:19):
it over. But the funny thing is that in these
models for their calculations, they've only ever gotten the urine
is like planet to tilt over about like sixty five
or seventy degrees. They can't get into tilt all the
way over to ninety 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
(33:40):
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 Uriness over on its side without
blasting all the ice from its moons. So that means
that if you hit Urinus with an object half the
size of Earth instead of twice the size of Earth,
(34:02):
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 happen maybe billions of years ago,
and we're doing these calculations and try to say, hey,
could this be an explanation? So we're building up more
(34:25):
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 work, Since 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
(34:46):
with this curiosity of the fact that there is still
ice on the moons of Uranus, which is not consistent
with having Urinus be impacted by an object twice the
mass of the Earth. So as you make more refinements,
you ask yourself more questions, as this explain this be?
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 he keeps passing those tests,
(35:08):
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. 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
(35:29):
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 Daniel and Jorge dot com. We
(35:52):
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.
(36:13):
Thanks for listening, and remember that Daniel and Jorge Explained
the Universe is a production of I Heart Radio. For
more podcast from my Heart Radio, visit the I heart Radio,
Apple Apple podcasts, or wherever you listen to your favorite shows.
YE
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 seemed like sort of decorations in
the sky. Now, of course, we know that there's much
(00:32):
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 the tiniest drop in intergalactic space.
And the stuff that goes on out there and the
rest of the universe is super crazy. It's a bonkers
(00:55):
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,
(01:26):
and I have the weirdest questions about our weird cosmos.
And welcome to the podcast Daniel and Jorge Explain the Universe,
a production of I Heart Radio 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
(01:50):
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
(02:13):
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,
(02:34):
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 noticed by now
(02:57):
is 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 and Jupiter, about chips approaching each
other near the speed of light, and about what knocked
(03:20):
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 want answered,
we answer every tweet. We're right back to every email.
Please send us your questions two questions at Daniel and
(03:41):
Jorge dot 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 zoo 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
(04:02):
schedule details about my public office hours. Check out my
websites at sites dot u, se I, dot edu, slash
Daniel where you can find all the information. Alright, 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 Jorgey. This is Andy and Indiana and I just
(04:24):
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 mall to buy a diamond for
an engagement ring, and instead wants to fly to Jubiter,
(04:47):
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,
(05:10):
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 or carbon. You can assemble these little bits
of carbon and lots of different ways that have lots
(05:32):
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
different materials. Right. It tells you that there's something deep
about the arrangement of stuff, That it's the arrangement of
those carbon molecules that makes a diamond a diamond, and
(05:53):
a piece of coal a coal, not the thing it's
made out of. And that's a deeper truth that we've
learned about the whole Nate you're 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 eighty ms of
lava or of hamster. It's all the same stuff, just
(06:14):
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 two
thousand 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
(06:35):
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. And 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
(06:56):
of the Earth. Most of the diamonds that are on
people's engagement rings walking around come from like a hundred
and fifty to two hundred 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 in the byproduct of coal. Getting squeezed because
(07:19):
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
dead plants. But diamonds have been forming on Earth since
(07:40):
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 the vertical pipes
(08:01):
inside the Earth. And the reason is that these diamonds
are formed deep deep under the Earth's surface two hundred 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
(08:23):
find them. In mind, 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 our 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
(08:45):
it's large enough that can have as much energy is
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 is definitely capable of
creating the conditions you would need to form diamonds. You
(09:05):
get super high temperature when that think 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 a meteor creater, this crazy hole in
the ground in Arizona, you can actually see these things.
They find these millimeter sized micro diamonds in meteor creater. Alright,
(09:28):
so what would happen if you actually took a chunk
of coal and went to Jupiter and dropped it 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
(09:51):
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 model 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 uranous and
(10:12):
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
(10:32):
sort of on 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 until these diamonds, which then
get heavier, fall deeper and deeper and they grow. And
nobody actually knows how big these diamonds can get. They
(10:56):
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 into probe it, but we
(11:17):
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, there were produced tons and tons
of diamonds every year, so they anticipate there are something
like ten million tons of diamonds on Saturn and Jupiter.
(11:42):
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 jubiter 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 bit fuzzy. There is a rocky, icy core,
but things get really dense before you even get there,
(12:05):
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 the point where it's
equilibrated right whereas 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
(12:27):
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 Urineus and Neptune, to contrast,
that the temperatures are much cooler and you don't reach
that like eight thousand kelvin degrees you need to melt diamonds.
So Urine is a Neptune probably have huge collections of
(12:50):
diamonds in their interior, but on Jupiter those diamonds may
have melted and contributed to these vast oceans of liquid
diamond It's fascinating. 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.
(13:11):
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
(13:32):
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
(13:54):
answer a couple more questions, but first, let's take a
quick break. All right, we are back and we are
talking about the crazy things that go on in our
(14:15):
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
(14:35):
to your episode about how special relativity affects how we
perceived 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 philosophies 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
(14:58):
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.
(15:21):
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
(15:44):
the universe, because it's there that the truth is revealed.
And we don't want just an intuitive understanding of the
universe that's 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.
(16:07):
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 Cole
has managed to touch on basically all the critical elements
(16:29):
of special relativity. So to answer this question, we're gonna
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
(16:52):
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
and special relativity because two different observers moving in 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
(17:14):
in a car moving at twenty miles an hour relative
to the ground, and you throw a baseball at twenty
miles an hour, how fast is that baseball moving a
relative to the ground. Well, you think, oh, that's easy.
It's twenty miles an hour from the car plus twenty
miles an hour from your arm, you have forty miles
an hour. And that's true for small velocities. But because
(17:35):
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
velocity is added 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
(17:56):
in a spaceship flying at seven tenths the speed of
light relative to the Earth, and you throw a baseball
with your amazing arm at seven tenths of the speed
of light in the same direction, do we measure that
baseball going at point seven plus point seven or one
point four times the speed of light. No, we don't,
(18:16):
because you can't just add those velocities. Instead, you get
something like zero point nine five 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
(18:37):
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 it's time running slowly, all right. So
with that in mind, let's dig into Cole's question. Cole says,
what happens if these two ships are approaching each other
(18:59):
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
(19:21):
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 twenty miles an hour, you could say, oh,
(19:43):
the cars are approaching each other at forty miles an hour,
but zoom back out to space. If both ships are
approaching you at seven tenths the speed of light, you
can't say that they are approaching each other at one
point four times the speed of light because the velocity
addition is not linear. Instead, on each ship they could
(20:03):
measure the speed of the other ship and they would
see something like 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 seven tenths the speed of light, but each
ship doesn't measure the other one is traveling faster than
the speed of light. Because you can't just add the
(20:25):
velocities linear, we have this crazy non linear 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 as faster than the speed
of light. That is, from Earth, both ships are moving
it less than the speed of light. But if you
(20:46):
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 is
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
(21:06):
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 the speed of light. And that's
the crazy thing is that different people can see the
(21:26):
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 could
(21:47):
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
(22:09):
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. But whether two things happen
at the same moment also depends on where you are
and how fast you're moving. And that leads us to
(22:30):
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 seven tenths of speed of light in opposite directions.
(22:51):
Both of these ships have a clock on them, and
they have awesome telescopes so that the people on the
ships 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 seven tenths to speed of light. Most people make
the mistake of thinking that you will feel time and
running slow. You won't. You always feel your time running
(23:13):
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
(23:35):
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 of the speed of light. And
so you see that clock running slowly. You think, for
every ten seconds that passes on your clock, you only
see one second tick on that clock. So that's really weird, right,
(23:57):
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 through their telescope
(24:19):
they see your clock running slowly. It's another example of
how two people to 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
(24:40):
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
(25:02):
sorts of contradictions. Well, you know, all 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
(25:23):
it takes 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 to 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. Alright, cold,
(25:43):
thanks very much for asking that super fun question. I
want to get to one more question, but first let's
take another break. Okay, we're back, and we are talking
(26:03):
about the crazy things that happened in our universe, things
that happened at light speed, things that happened it's 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 Brendon from St. Louis, Missouri, and I have
a question for you guys that I've been thinking about
(26:24):
for a little while. Now. You 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 uriness to make it sideways and could that have
been what gave it its rings or is that just
wild speculation? Would love you guys, input on something like this.
All right, thanks very much for that awesome question. I
love Urinus because Urinus is really weird. It's not just
(26:46):
that it makes diamonds that rain in the interior. It's
a very unusual planet relative to the other planets in
our solar system. Right, if you look at the Solar
system sort of from the top down, the Sun is
spinning counter clock wise, 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
(27:09):
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.
(27:29):
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 than 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
(27:50):
faster because she has to have a higher rotation rate
to have the same total angular momentum. And so as
that huge cloud of 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
(28:10):
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 solar system. And
so urine is in particular is an odd ball, quite literally,
(28:33):
because it's tilted more than ninety 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 urine is is not a small thing, right,
it's not like one tiny little rock that happens to
be spinning the wrong way. It's an enormous ice giant
(28:55):
of a planet. It's got a lot of mass, which
means it has a lot 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, it's north pole points
(29:15):
towards the sun right. That makes really weird seasons, and
the definition of north pole is sort of odd on
Urinus 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
(29:36):
is formed by like the slashing 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
(29:59):
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 Uriness maybe having such a
strange configuration because it got knocked into by some huge
(30:22):
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 Urin. It's
you know, a little rock like the size of the
one that killed the dinosaurs. This is a rock twice
(30:42):
the size of the Earth that collided into Urinus 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 movie to shame. I would have loved to
see that sort of real effect in action. Of course,
(31:05):
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 urine is.
But when we look, for example, at the moons if
urine is, 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.
(31:27):
But we don't really see that, and so there's not
the evidence of that huge collision. But we still have
urine Is 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 slash around from object to object, and you might wonder, well,
(31:51):
how can that happen without collisions? Will remember that there's
still gravity here, and there's lots of different objects slashing around.
Urinus is there, and it has rings and very barious
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
(32:13):
momentum because of these gravitational interactions. And so recently there's
been a new theory for how Urinus might have gotten
its weird direction and weird spin, and it has to
do with how Urinus is 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.
(32:35):
It orbits it and an ellipse, and an ellipse, un
like a circle, has a preferred direction that a long axis, well,
that long axis moves around the Sun, and that's called precession.
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
(32:56):
you think about a gyroscope here on Earth. You can
spin a gyr scope and then see it's sort of
like tilt over. They're all these really complicated dynamics with
angular momentum that can get your brains would twisted up.
But they have done these calculations and they've done these models,
and they've seen that like a gyroscope effect. If you
get Uriness in the right configuration, then it's spin procession
and it's orbit can interfere in a way that tilts
(33:19):
it over. But the funny thing is that in these
models for their calculations, they've only ever gotten the urine
is like planet to tilt over about like sixty five
or seventy degrees. They can't get into tilt all the
way over to ninety 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
(33:40):
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 Uriness over on its side without
blasting all the ice from its moons. So that means
that if you hit Urinus with an object half the
size of Earth instead of twice the size of Earth,
(34:02):
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 happen maybe billions of years ago,
and we're doing these calculations and try to say, hey,
could this be an explanation? So we're building up more
(34:25):
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 work, Since 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
(34:46):
with this curiosity of the fact that there is still
ice on the moons of Uranus, which is not consistent
with having Urinus be impacted by an object twice the
mass of the Earth. So as you make more refinements,
you ask yourself more questions, as this explain this be?
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 he keeps passing those tests,
(35:08):
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. 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
(35:29):
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 Daniel and Jorge dot com. We
(35:52):
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.
(36:13):
Thanks for listening, and remember that Daniel and Jorge Explained
the Universe is a production of I Heart Radio. For
more podcast from my Heart Radio, visit the I heart Radio,
Apple Apple podcasts, or wherever you listen to your favorite shows.
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Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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