March 31, 2020 • 39 mins
Daniel and Jorge answer questions from listeners, like you!
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Episode Transcript
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Speaker 1 (00:09):
Hey, Jorney, Maybe you're not aware of you recently coined
a word that I now use all the time. Oh yeah,
I've been in his movies. Know. The word that you
made up that I really like is the word engineeringly.
That was pretty a pretty good word. But how do
you use it in a sentence. Let's say you could say,
for example, a warp drive is physically possible, but engineeringly impossible.
(00:32):
That just sounds to me like you need better engineers.
We definitely need better engineers, and I hope that they're
out there in our audience listening today because we have
some engineeringly very challenging projects on the docket. Ye hi,
(01:02):
am orhammy cartoonists and the creator of PhD comments, Hi,
I'm Daniel. I'm a particle physicist, and I'm happy to
put off my problems onto engineers, even your personal problems.
There does seem to be a proliferation of engineers. You know,
back in the day that was mechanical electric. You make
it sound like we're a pest or, but you know,
now you've got the software engineers, you've got social engineers,
(01:25):
You've got every kind of engineer. It's crazy. So yeah,
maybe Daniel's personal problem engineers, I supposed to physicists who
there's only one kind. There are only a few of us. Yeah,
that's true. There's like solid state matter, wet matter, dark matter.
It's been a while since we invented a new kind
of physicist. Yah, maybe it's time. Maybe it's time. Yeah,
(01:46):
Daniel's personal problem physicists. I don't think any of my
personal problems can be solved with physics. That there's learnal
laws there to be found. But welcome to our podcast.
Daniel and Jorge explained the Universe State production of Hard Radio,
in which we focus on the questions that can be answered,
the questions that might one day in the future be answered,
(02:07):
questions about how the world works, about what the universe
is like, how it will end, and how it is
put together on the smallest scale. Yeah, we love questions,
and we love questions for which we know the answers
and we know the question. We love the also questions
for which we don't know the answers, because there are
still a lot of questions out there in the universe
that nobody knows the answer to, and often on this
(02:30):
podcast we take a tour of some of those questions.
We show you what's in the mind of scientists at
the forefront of knowledge is they try to peel back
a layer of reality and expose the universe as it
really is. And sometimes we take you on a tour
of the minds of our listeners, thinking about what everybody
out there is wondering about. Yeah, and we love taking
(02:51):
lists questions from listeners because they really sort of give
us an insight into what people are thinking and what
they're what our podcast is kind of make them think about.
That's right, and not just because they give us sort
of like a checkpoint so that we understand what listeners
are getting and what they're confused about. But sometimes listeners
questions really put their finger on something amazing about the universe.
(03:13):
When I teach, you know, freshman physics here you see Irvine,
it's when they ask a question that it makes me
think about a topic in a new way, makes me
explain in a new way, and then it really makes
me understand it. So listener questions are really a source
of insight. Yeah, And let's face it, we have I
think the best listeners in the universe Daniel Podcast on Earth,
(03:35):
and I would say in anywhere else in the universe,
I think we have the best listeners. That's right, And
we're talking specifically about you. You know who you are.
We're talking about you right there listening to us right now.
You're the best. You're our favorite listen. You're the best looking,
you smell great today, and you ask awesome questions and
tell my kids that all the time. I'm like, you're
my favorite daughter, and she's like, I'm your only daughter
(03:58):
that I know of. Daniel and Jorge dig Into or
his sort of past. Hey, you know, if this is
going to be Daniel and Jorge starting to tell a novella,
then you're going to have some sort of you know,
other family show up at some point in season seven.
My evil twin twins genetically the same. Does that mean
(04:20):
their kids are sort of also like your kids? Boy? Interesting,
he's had a great listener question. Yeah, Or does that
mean if you can have, if you can be twins
and one of you is evil, does that mean that
evil is not genetic? Or maybe you are evil but
you do you don't know it. There are no good twins,
is that what you're saying? Well, they should either both
be good or both be evil. I'm sure that all
(04:42):
the twins listening right now are both good? Well, anyways,
we do have the best listeners and they do ask
the best questions that they send us through Twitter or
Facebook or Instagram or by email. And if you're out
there listening to this podcast and you have a question
about the universe, you can also write it to us
and we will eventually get to it on the podcast.
(05:02):
That's right, And we answer all of our listener emails
pretty promptly. Sometimes people writing asking a good physics questions.
Sometimes people writing asking sort of off the wall questions. Uh,
nobody so far is asking for marriage advice. But here's
a question we got last week which sort of made
me chuckle. It's from Gridget saying and here's what he
had to say. He wrote, if we assume the world
(05:25):
is a simulation, do you think there's only one conscious
being and the rest of the world are just biological zombies?
Or everyone is conscious? I love this question. It's like
am I playing a video game? Or are we all
playing a video game together? It's like are you a
non player? Yeah? Yeah? Or is there somebody really in there? Interesting? Well,
(05:47):
it just gets to the bottom of consciousness, right, like
kind of machine be conscious, kind of machine be conscious. Yeah,
and maybe this guy spends a lot of time in
video games wondering if those other players are real or not.
But a fun question, but not one that I, you know,
necessarily have any expertise or ability to answer. So I
could pontificate as a physicist, but I think the physicists
(06:09):
spend too much time talking about things outside their area
of expertise. So I'm gonna have to point on that one.
Maybe you've noticed that what if? What if you're playing
a bit of games where you have to kill zombies,
then technically are those zombies? But are those zombies conscious?
But they can't because there's zombies? Yeah, well you could
be committing digital moral crimes. But we love answering listener
(06:32):
questions and sometimes we have episodes where we ask to them,
and so today is what are those episodes? So today
on the program, we'll be tackling listener questions about the universe.
That's right. We'll be touching on exotic matter, will be
building roads that span the Earth, and we'll take our
minds to other galaxies and wondering what life is like
(06:56):
out there aliens. Basically, we're feel I feel like we
can have a listener questions episode without touching the hitting
the alien button. Are you saying that's because our listeners
are fascinated with aliens? Are you suspecting that I'm picking
the alien questions out of the slush pile. I feel
like there's a Van diagram there listener questions and things
(07:19):
Daniel loves to talk about. If you have a question
about anything, dear listeners, just put the word alien in
it and it will increase your chances that we'll talk
about it. That's fair, that's good advice. Yea, I have
a question about dark matter. Just wonder if dark about
her could be made by aliens? And well, I'm sure
we'll consider it. My kids know that already. They're like, hey, Dad,
can I have ten bucks? It's for aliens? Yeah, sure,
(07:41):
here we go. All right, So today we have three
questions from listeners from all around the world, and so
we'll be tackling each of these questions one by one.
And so the first question comes from Maria from Canada
and she has a question about exotic matter. Here's your question. Hi,
Daniel and Jorgey. My name is Maria and I'm a
listen from Victoria, Canada and I was wondering what's exotic matter,
(08:05):
how is it different from dark matter or antimatter? And
how many different kinds of matter even are there? Anyways,
thank you so much, awesome questions. I feel like she's
sort of get throwing little shaded physicists. I felt that,
I felt that shade, like, hey, get this under control,
Like people are ridiculous, Yeah, that this matter naming is
getting out of control. It's we have as many kinds
(08:27):
of matter as there are like fields of engineering, and
that's absurd. We we need a new feel for every
kind of matter you guys come up with. So it's
not our fault. We need exotic physics and exotic physicists.
We're just trying to plug the holes of physicist are creedive.
Thank you, by the way for your tireless work plugging
our holes. We just need to have a lot of
kinds of matter in our universe. There's, for example, baryonic matter, antimatter,
(08:51):
dark matter, exotic matter, supersymmetric matter. Yeah. Yeah, the list
goes on. And this is a totally great question, and
it's a fair question also because this term is used
in lots of different ways. In a very general way,
people use the phrase exotic matter to me literally, just
that like matter that seems kind of weird, like exotic,
(09:11):
something different from the every day you know, the everyday
matter is made of quarks and electrons, and so from
that definition, exotic matter could be like dark matter, you know,
or other weird stuff that's out there. Oh boy, now
you're just making it worse, Daniel. Now you're like overlapping
all these matter designations. We're not great at that. In
(09:31):
particle physics, you know, matter could just be any matter
that is against something. Yeah, it could be. So it's
it's a different opinion. It's a very vague tournament. And
it could even be weird forms of familiar matter. Like
if you take atoms and you cool them down and
make weird quantum states like Bose Einstein condensates, some people
would call that exotic matter. Or if you make super fluids,
(09:54):
you could call that exotic matter. Well, well, let's take
it's a step back here. You're saying that the word
exotic matter is not well defined in physics. Yeah, if
you just google what is exotic matter? For example, you
will see articles physicists discover exotic matter, but then it
turns out it's actually about super fluids, or physicists use
exotic matter to communicate quantum mechanically and then it turns
(10:16):
out it's just bosion stain content. States m hmmm. So
you're saying, just like in our culture, the word exotic
is sort of outdated and inappropriate. Yeah, it's a little bit.
It's been a bit abused. But there is also sort
of a narrower version of exotic matter that has a
very specific, fascinating meeting in particle physics that I think
(10:36):
we could dig into. Oh I see, all right, So
in general, it can just mean any kind of non
normal matter, weird, spooky Halloween matter in the loose sort
of definition of yes, spooky Halloween matter, or you know
matter from the Orient, which is that racist. Yeah yeah, yeah,
(11:00):
extern centric and but um no, you're saying, and in
general sense it just means weird matter. But there's also
sort of maybe a hardcore group of physicists who are like, hey,
this means something very specific. Yeah, they rock out the
heavy metal and they talk about this kind of matter.
They are hardcore, and that's matter with negative mass. So
(11:20):
in particle physics we talk about exotic particles or exotic
matter and what we mean are particles that have negative mass,
Like you know that mass is something we attached to particles,
and I have mass and you have mass, And a
fascinating thing about mass is that it seems to always
be positive. So we've invented this idea. Maybe there are
particles out there with the other kind of mass and
(11:42):
negative kind of mass. Mm hmmm, because right, because mass
is just kind of a label, right, it's not actually
like stuff. It's just kind of a like an electric
charge can be positive or negative. Yeah, we don't really
understand it. And if you zoom down to an individual particle,
particles have no volume. They're just points and base with labels, right,
like electric charges, you said, And mass is another property,
(12:04):
and mass is a property that these particles get from
interaction with the Higgs field. But the fascinating thing about
mass is that it always seems to be positive. Right.
We measure the mass of all of these particles and
we see that they have positive mass, and that has
fascinating consequences because the Higgs field always gives these particles
positive mass, or like the interaction is always positive, like
(12:25):
I has anyone had a bad experience with the Higgs field?
I guess it only has five star reviews on Yelp.
So yeah, in the Higgs field widely loved, would recommend yes,
Higgs field good. Um, But did you know what I mean? Like,
if something has negative masses, that mean that when it
interacts with the Higgs field it gets the negative mass
(12:45):
or what does that mean? Well, if a particle had
negative mass, we don't know how it would get that mass.
One way to get mass is to interact with the
Higgs field. We think there might be other ways for
particles to get mass too, but we've never seen one
like that, So there could be various ways for articles
to get mass. It doesn't just have to be the
Higgs field. The Higgs field just kind of determs how
it moves in the universe. Right, But you can still
(13:08):
have mass independent of the Higgs field. Yes, you can
get mass without getting it from the Higgs field. We
haven't ever done that, but like, we don't know neutrinos,
do they get mass from the Higgs field or not?
Do they get mass in this other weird way And
we can dive into that and a whole other podcast,
But I think the important concept to remember is what
you just said is that it changes how you move
through the universe. Often, when we talk about mass, we
(13:29):
really mean two different things. One is inertia, like you
give something a push. It takes a push to move something,
to change something's momentum, to get it started, takes a push.
We call that inertia. Really, that's mass, right, and that
comes from the formula F equals M. A force is
mass times acceleration. To accelerate something, you have to apply
(13:50):
a force, and the mass is the relationship between those two.
So that's mass. Concept Number one is inertial methods. How
hard it is to push? Yeah, how hard is it
to push to get it going? And also how hard
is it to slow it down? Like a semi truck
has a huge amount of mass, takes a huge force
to slow it down. Can something have negative inertial mass?
Is that possible where you like, you push it and
(14:12):
it goes faster, or you know, like it pushed you
push it and it actually pulls you or something, and
you know what, that's what would happen if you gave
it a push to the left and it had negative
inertial mass, it would move to the right, it would
push you, push you back. Yeah, so the force would
be the opposite direction of the acceleration. So the weird
thing about negative mass is like, it seems weird. It's
(14:33):
totally counterintuitive, but mathematically it kind of hangs together, like
we don't have a reason to believe it doesn't exist.
You could fit it into all of our equations. We've
just never seen an example of it. That kind of
weird example could happen where you like push it one
way with the with the force field or something, but
it goes the other way. Yeah, you could do that
(14:53):
in theory. It's possible. We've never seen it, but you
can work out all the equations of motion and it works.
So you push into the left and it moves to
the right. But that's only one way of thinking about mass.
Is a whole second concept of mass, which is mass
in gravity. Like two objects that have mass feel gravity
and attract each other. So so if something has negative mass,
(15:16):
it could maybe repel another thing, would mass. Yeah, the
fascinating thing about positive mass and gravity is that gravity
is one of the only forces that so far seems
to be just attractive. Right, you get pulled in by
the sun, you get pulled in by the moon. There's
no way, you get pushed by gravity, whereas like electromagnetism,
there's a positive and negativity, and if you have the
(15:37):
same charges you get repelled and gravity it is only
positive and it seems to only be attractive. So if
you add negative mass, then yeah, you could get repulsive gravity.
Or I guess maybe in like the Einstein space bending picture,
it would be sort of bend space the other way. Yeah,
instead of having like a dent down into space, it
(16:00):
would be like a like an explosion of space a
little bit. So things like slide away from you like
a z in space, like a like a bump a space.
Don't pop at ZiT. That's like a gravity bomb. Yeah,
you have a negative experience. Don't do it. It's weird though,
because this is a little counterintuitive. You know that positive
(16:20):
mass of course attracts other positive mass. It would also
attract negative mass, and negative mass would repel negative mass
and also positive masses. Wait what, it wouldn't be like
electrical charges. It's not like electrical charges because you just
said that. We don't think of gravity as a force.
We think as a bending of space. So positive mass
(16:42):
makes like a dent in space like a whole in
space for things to fall into regardless of their mass,
and negative masses make space zits. That was actually Einstein's term,
and is it z it's their spation and now that's
a joke. But a negative mass make these would make
these like you know, or I'm gonna say zits in
(17:04):
space because regardless of the mass of the other thing. Right, So,
positive masses attract other positive or negative masses, and negative
masses repel negative or positive masses. It's like the opposite
of a black hole. Yeah, and it's weirdly sort of asymmetric, right.
(17:24):
You like to think about the forces as being symmetric,
so like it depends on the product of the charges
or something, but it wouldn't be. And that means if
you have like a positive mass and a negative mass
next to each other, then the positive masses pulling on
the negative mass, but the negative mass is pushing on
the positive mass. Um what would happen? They would actually
(17:45):
just like lead to this runaway motion because the positive
masses pulling on the negative the negative is trying to
repel the positive. Attraction of the negative actually pushes the
other direction, right because of negative and inertial mass, And
it would just skip out of town. Let's skip out
of town for real. Well, we don't know, Like this
(18:07):
is the idea, so we've never seen this stuff. It's
just sort of an idea, and and it would be
pretty helpful because if we did have exotic mass, we
could use it to, for example, stabilize wormholes and travel
through the galaxy and this kind of stuff. But we've
never seen any of it. It's just sort of like, yeah,
I guess that's in the lad. The next question, which
is is this even real or is it just theoretical.
(18:29):
It's just theoretical, but it's important to recognize these sort
of theoretical opportunities. Some of these other kinds of matter
we talked about, like antimatter. They started out it's theoretical,
and somebody noticed, hey, the equations also work if you
flip all these signs and make this other weird kind
of matter. So maybe that's real, and it turns out
it's true. So seeing these mathematical symmetries are often guides
(18:51):
actually binding stuff in reality, and that will tell us
more about the universe. Yeah, but the universe is asymmetric sometimes,
like there's a lot of matter out there, very very
little antimatter, if any. We don't know why that is.
So there's a lot of positive matter out there, none
or maybe very little negative matter. Why is that right?
Fascinating questions? Yeah, maybe not all the matter matters. All
(19:15):
matter matters, man, but all right, so, um, it seems
like to answer Maria's question, exotic matter. Um can mean
a lot of things, but it generally it's terribly used
just to me, like not normal matter, meaning the matter
you and I are made out of. It's kind of
weird or unusual. Some physicists call that exotic matter. But
there's also sort of the hardcore definition, which is that
(19:38):
it means matter with negative mass, which is theoretically fascinating,
totally possible, but never been seen. But you know, she
also asked another question, which is how many different kinds
of matter are there? Anyway? And that's such a good question.
It's a question that I have also because we see
these symmetries in nature. We see like, oh, there's matter
and antimatter, there's maybe positive matter and negative mass matter,
(20:02):
and there's other symmetries like we talked about supersymmetry on
this program, like maybe every spin half particle has a
spin one particle that that balances it, and vice versa,
and all these symmetries tell us something deep about the universe,
about the way it's put together, about what it reflects
that its deepest level, And we don't know what the
answers are. But every time we find a symmetry, I
(20:24):
feel like it's revealed something about the universe that we've
been desperate to find out. Every time you find a
new kind of matter or think up but you kind
of matter, it kind of pushes your definition of what
can exist. Yeah, and these symmetries are really important. You know.
We talked also on this program about how the universe
is left handed. It prefers particles that spin in a
(20:45):
certain way relative to their motion. We don't know why
that is, and so people suggested and maybe there's another
kind of matter called mirror matter, where it's the opposite.
And every time you have these symmetries, you have to ask,
why is it this way and not the other way?
Why is the universe sort of by furcated into two options.
What does that mean about the nature of the universe
At some higher temperature earlier in the universe, was this
(21:07):
all unified into something beautiful? And crystalline, and then it's
just sort of cracked and fell apart. We don't know.
I think my favorite kind of matter are the matters
of the heart. Daniel. All right, well, we hope that
answered your question, Maria, thanks so much for asking the question.
And so let's get into our two other questions for
the episode, and these are about the biggest road ever
(21:28):
built and also about intergalactic aliens. But first let's take
a quick break. Alright, we're answering listener questions today. Answer
(21:49):
Our next question comes from Rahul from India, and so
he has a question about an interesting idea for an
infinite road. Here is so, imagine you start building a
bridge or a highway above the surface, and it goes
all the way around the earth and meets each other.
Now you have this one long, continuous bridge. So obviously
(22:11):
those bridges have pillars, and now you decide to bomb
all the pillars that supposed the bridge at the same
exact time. So what would happen to the bridge? Will
it stay floating above the surface or will it fall down?
And at which direction? Or will it hoholla hoop the earth?
And the second condition is what would happen if the
(22:33):
Earth was perfect sphere. So I think this one might
be more in your alley because it's kind of a
question about, you know, whether something is engineeringly possible. You're like,
this is not interesting to me, or hey, you can
take this one. It's just about building a road. Now,
if aliens built a road, that's just positive that. Let's
(22:55):
just let's imagine we're in an alien planet. But the
question is kind of interesting, and I have to say
it took me a second to sort of get it.
So he's he's asking, what if you build a road
all around the Earth, like a suspended road, right, and
it goes you know, from it starts here in California,
goes through the US, crosses the Atlantic, goes over Europe Asia,
(23:18):
and then it comes back around and connects in a
perfect circle to where we started the road. And then
so you build this road, it rings the earth and
then you take out all the columns, the pillars that
supported simultaneously with bombs. Right. I like that detail. Yeah,
that would probably the funnest part actually, But you remove
(23:39):
the pillars, all of a sudden, does the bridge stay
up floating or does it all fall down? Yeah, And
it's a fun question because you imagine you build a road,
you support it with pillars, you knock the pillars down,
the road falls down. But in this scenario, you've made
it go all the way around the earth. And so
then he's wondering, like, is it possible for a road
to float in the air? Would it be in orbit, Daniel?
(24:00):
Would it just be sort of like a pula who
held around your waist. Let's answer this from a physics
point of view, which means we have to like simplify
things a little bit, and then we'll make it a
bit more practical. So first let's start with the let's
hear answer A from Daniel. First, is a perfectly spherical earth,
like very smooth, no deformities, etcetera. And so the road
(24:21):
is like a hundred meters or a hundred feet or
whatever above the surface all the way around the Earth.
Now that scenario you knock out all the pillars. Think
about the gravitational force on this thing. It's going to
be balanced, Like the Earth is pulling on one part
over California, but it's also pulling on another part over China,
and those two things are going to balance. And if
(24:42):
the road really goes all the way around the Earth.
Then for every part of the road there's a counterpart
that's balancing its force, and so it should just hover there.
So that's your answer that it would stay up floating.
If it's a perfectly spherical Earth and a perfectly circular road,
it would stay up there floating. You don't believe it, well, Um,
so I have an engineering answer, but I'll just keep
(25:05):
going with your physics answer here for a bid. The
other way to think about it, it's just by symmetry,
like if it goes in one direction, which direction could
it go? You have to choose a direction, And if
the Earth is a perfect sphere, then there's no preferred direction,
so it can't go in anywhere any direction. So it
would keep rotating with the Earth. It would keep rotating
with the Earth, Yes, but it wouldn't have to rotate either.
What if something knocks it off of alignment a little bit,
(25:28):
Like what if the wind blows an in on one
side of the Earth and not the other, and now
it's a little bit closer to one side than it
is to the other side of the Earth. Yeah, so
we're leaving the world of perfect physics scenario and we're
adding things like wind and disturbances, And you're right that
it would be very unstable because if it moves like
(25:48):
one foot closer to the Earth here, then so I'll
foot further from the Earth on the other side. So
now the force is stronger on this side and weaker
on the other side. So it's unstable. It's when does
it deviates from this sort of like perfect spot it's in,
it's going to come crashing down. Oh, I see it
moves a little bit, and so now let's say it
moves down here in California, so it's closer to the Earth,
(26:11):
and now the center of the mass of the whole
thing is a line with the center of the Earth.
Wouldn't that just make it come back to the center
of the earth realign I'm pretty sure it's unstable. And
the reason is that the mass of the Earth is
distributed as a function of the radius. So you can't
just think of the motion of the center of massive
two objects. These are two large distributed objects, and as
(26:36):
one side of it gets closer to the Earth and
the other side gets further that you're gonna get a
relative force difference on the whole thing that's going to
push it further from stability instead of closer to stability.
But I haven't done the simulations. So maybe we should
actually build this thing and find out to answer the
Rahul's question. Let's spend a trillion dollars. Why not? You
(26:57):
got something better to spend it on. So it sounds
like a plan. Let's crowdsource it. Everybody's send in ten
bucks to build Rahul's road. Okay, So you're saying that
from a physics point of view, it is possible for
this thing to exist if nothing touches it or knocks
it out of bound, or moves it at all a
little bit, it would just float above the earth, certainly
(27:18):
the Earth, like a like a ring, like a hula. Yeah,
And I think the key there is that as soon
as you build something that's the size of the Earth,
you can no longer apply the rules of your intuition
that you apply to things that are the size of you,
or your house or even your city. Right, Like, things
can float up in space in orbit. That seems weird.
Why don't they fall? Right? That's because they're largely moving
(27:40):
at cosmological astronomical speeds. And so here's an object really
of astronomical scale, and so it wouldn't necessarily fall into
the earth. It's like an object that spans both sides
of the Earth, of the center of mass of something big. Yeah,
and this actually appears in a novel. I mean, not
as a road, but in Neil Stevenson's recent novel seventives.
(28:02):
Earth becomes uninhabitable because of X y Z plot devices
that won't spoil, and humanity builds a huge ring around
the Earth, like a mechanical ring, and actually live on it. Well,
that that, I think that's the physic times for I guess,
you know, as an engineer, when I saw this question,
I didn't, you know, sit down and make the calculations,
but I think right away my thought was that no,
it would it would fall apart right away. You mean,
(28:24):
because you couldn't build something that big, that was rigid.
I think I was thinking, you know, the limitations of
whatever you build it out of, you know, would collapse
like nothing. I don't think anything that we know of
can withstand those kinds of forces, and so we just
crack and fall apart. You mean, forces from like an
entire four thousand mile road segment pulling on individual piece. Yeah,
(28:46):
you know, like there's a reason you can't just make
a suspended bridge without any columns. Like if this was possible,
then you could just build a bridge, and if you
make it the curvature of the Earth, then it would
just stay up, wouldn't it if we just hold both ends. Yeah? Well, uh,
not an expert on mechanical engineering, So I'll take your
word for it that I think you're right, And I
think there are also other practical issues also, you know,
(29:08):
like you have to have it at the same height
above the earth all the way around, but of course
there isn't a constant height above the earth. You know,
you have to clear mountains and all sorts of stuff,
and so that would throw the whole thing off balance.
All right, Well, I think that's maybe whose question answer,
which is that it's sort of would be possible, and
it would hang there floating above the earth if nothing
(29:30):
touched it or nothing perturbed it at all, no weather,
and if it was made from like this incredible material
that that would would stand these incredible forces, which um,
I'm not sure we have. That we definitely don't, because
if we did, we could build a space elevator, which
is sort of weird. And similar ways, something hanging out
(29:51):
there in space you can actually climb up. And one
of the limitations there is just building a rope. They
could even hang That's that that is that long? Right? Yeah,
something I can that wouldn't just crack under under all
those forces. It's under but definitely cool and fun to
think about. Thanks for Hull for sending in your crazy question. Alright,
are we ready to talk about aliens? Because I'm ready,
(30:12):
You're always ready, Daniel. All right, let's talk about aliens,
but first let's take a quick break. Al Right. Our
last question comes from Nanu from Argentina, and she has
(30:34):
a question about life from other galaxies. So here's Nanu.
Why wouldn't we talk about life in other planets? Do
we always talk about it in terms of our own galaxy?
Do we not consider life in other galaxies because they're
so far away it would be inconsequential for us. I
still have hard time figuring out distances, So I am
wondering could it be possible for millions of years old
(30:55):
alien race to take up into galactic trouble and arrive
to our own galaxy? All right, Daniel, did you just
get really excited when you opened up your in Boston
saw this question. Your hearts start racing a little bit.
You get excited. I got excited, and then I got
a little offended. You know. She said, what do you mean? Well,
she said, how can we never think about intergalactic aliens?
And I was like, what are you talking about? I
think about intergalactic aliens all the time, and it's one
(31:17):
of my favorite things to think about. I think maybe
she thinks she's talking culturally, the culture and in general
or responsible scientists rarely talk about intergalactic aliens. Yeah, I guess,
and it's that true. Do I guess? Do most people
think of aliens is coming from this galaxy? I think so.
Even in science fiction, often the drama takes place across
(31:39):
the galaxy or in one galaxy. And there's a reason
for that. The reason is that galaxies are huge, right there,
big enough to span enormous space operas and lots of
different empires and thousands and billions of stars. Plus they're
super far apart, so it's like each galaxy is an
island and all the other galaxies they're so far away
(32:01):
they're almost irrelevant. It's almost impossible to think about communications
between galaxies, or to travel between galaxies, or travel between galaxies.
You know, not to mention like intergalactic marriages. You know
all the problems that would raise a long distance I know,
you've got the kids over there for one weekend. I
got the kids over here for another weekend. It's a nightmare.
But let's give them a sense of scale, right, Like
(32:22):
the Milky Way is like a hundred thousand light years across.
That's already like, it's incredibly big. Even if you were
going at the speed of light, it would take you
a hundred thousand years, Yeah, to go from one end
to the other. Yeah, exactly. So it's hard to even
imagine having like an empire that spans the galaxy because
you send people a message like all right, let's raise
(32:43):
taxes one percent, and it doesn't get there for a
hundred thousand years. It's impossible to coordinate. That's why people invent,
you know, faster and light travel and faster than light
communication just to get stuff done within one galaxy in
novels and movies and hopefully one day in reality, but yes,
mostly novels and movies. Yes, you seem to mention it
like because we had, we already have that. People are
(33:05):
working on it. People are working on it. Hey, we
were talking about wormholes a minute ago, right, So yeah,
but you were saying, so the galaxy at typeople of
galaxy is a hundred thousand light years wide, and but
the distance between galaxies is you know, many times that
over by several orders of magnitude. Yeah, like the nearest
(33:26):
galaxies Andromeda, and that's two and a half million light
years away, right, it's and a half million years light
years years. It's twenty five times as why is the
whole galaxy? It's like if you have a house and
the neighbor's house is like, you know, blocks and blocks
away from you. So we're basically living in the middle
of the woods. So maybe that would explain why we
(33:48):
don't see it much in movies and novels because you know,
the plot logistics, which is be too much but um,
and also I think maybe it's also kind of recent.
You know, this idea that there are other galaxies. It's
kind of new, isn't it In the last fifty to
sixty years or something like that. Before that we thought
like our galaxy was it. Yeah, it's about a hundred
years old. It originates with Hubble. He's the guy who
(34:11):
measured how far away these little smudges in the sky
where he thought maybe they were nebula, they were gas clouds.
He measured their distance and found that they were crazy
far away. They were further away than all the other stars.
And that's what made him realize, oh, these are other galaxies,
and the whole universe just became much bigger in his mind.
So you're right. It's but we've had about a hundred
(34:31):
years to get used to this idea that the universe
is incredibly vast, but we haven't sort of mentally populated
it with aliens. And I think you're right. And one
reason is that they're just so far away it seems
almost irrelevant. We may never hear from them, or see
them or visit them. We may never that's true, but
we can still think about them. And I think a
really fun angle on this question is wondering, like is
(34:54):
life more likely to occur in those galaxies or in hours?
Is our galaxy unus usual? The same way we think
about is our solar system unusual in our galaxy? We
can ask is our galaxy unusual in the universe for
us to have developed here or evolved here? Like maybe
um most like maybe all other galaxies are too dangerous
(35:15):
for life to evolved in. Yeah, maybe we're in a
special place, right, or maybe we're in a totally vanilla galaxy,
and so we do know something about that, right. We
know that the Milky Way is a spiral galaxy, and
spiral galaxies are one of the most common kinds of galaxies.
We look out in the sky, we see lots and
lots of spiral galaxies. So there doesn't seem to be
anything particularly weird about our galaxy. It's not the smallest,
(35:37):
it's not the biggest, it's not the brightest or the darkest.
It has dark matter like other galaxies. So it's sort
of a generic galaxy. I mean, I love it. It's beautiful. Um,
I don't mean generic in a bad way. I mean
the generic in a totally vanilla way, by which I
mean that there's possibilities for life in other galaxies the
(35:58):
same way there is here. I wish you may And
it's the example by which all other galaxies are sparring too.
I mean, it's the role model galaxy. It's the exemplary
galaxy excisely, and it means that if there's life here,
there's no reason to believe there couldn't also be life
in those other galaxies? But could we able to find it?
Could we ever communicate with them? Could we ever shake
hands and spend time at a chalkboard, you know, revealing
(36:21):
secrets of the universe together. Oh boy, that's hard to imagine.
But but maybe not that hard to imagine. I mean,
if we can imagine us contacting aliens within this galaxy,
you know, them crossing the large amount of space between
us and them. You know, it's not that hard to
imagine doing that twenty times over to do it between galaxies. Right,
(36:43):
you won't drive an hour down here to Irvine to
hang out with me, but you'll drive twenty hours somewhere.
Is that you're saying. I'm saying if I really wanted
to see you, the difference between one hour and twenty
five hours wouldn't be because if I was an alien,
then you would drive twenty five hours to come back
to me. If it took twenty five seconds to go
see Daniel, I don't know if I still would. Oh no,
(37:06):
it's a good point. Um. You're right that if we're
going to explore our galaxy, we either need to do
it very very slowly, over sillions of years, or figure
out a way to overcome these distances which are already
an obstacle in our galaxy. And once we do that,
then maybe we could also hop to nearby galaxies. Yeah, right,
Like if you invent or you figure out how to
do wormholes or warp draws or suspended animation, what's the
(37:29):
difference between a year and twenty five years to go
to another galaxy? That's true. And you know, while we're
tossing our ridiculous ideas, remember our recent episode about stellar engines.
We could drive the Sun out of the Milky Way
and go visit another galaxy. We could like move galaxies
and go hang out in Andromeda. All right, Well, to
answer no question, I guess the answer is, we don't know.
(37:51):
We don't know why we don't think about any for
another galaxy, but maybe we should because it's not that
far off from aliens in our own galaxy. Yeah, and
it's true, none new that in millions of years, alien
racist could use intergalactic travel to to come here and
tell us all about what it's like to live in
another galaxy. And they'd be like, whoa, this is a
better galaxy. You're right, it has better reviews. I'm yelled.
(38:15):
So thank you to everybody for writing in those amazing questions,
and thank you to everybody else who's writing in questions
on a daily basis. We'll get to your questions as well,
and if you have a question, feel free to send
to us. Daniel likes to sit around and answer questions.
I like to be distracted from my real job by
thinking about your crazy ideas about physics. So thanks for listening.
(38:37):
We hope you enjoyed that. See you next time. If
you still have a question after listening to all these explanations,
please drop us a line. We'd love to hear from you.
You can find us on Facebook, Twitter, and Instagram at
Daniel and Jorge That's one word, or email us at
(38:59):
feed act at Daniel and Jorge dot com. Thanks for listening,
and remember that Daniel and Jorge Explain the Universe is
a production of I Heart Radio. For more podcast from
my Heart Radio, visit the I Heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows. Yeah
Hey, Jorney, Maybe you're not aware of you recently coined
a word that I now use all the time. Oh yeah,
I've been in his movies. Know. The word that you
made up that I really like is the word engineeringly.
That was pretty a pretty good word. But how do
you use it in a sentence. Let's say you could say,
for example, a warp drive is physically possible, but engineeringly impossible.
(00:32):
That just sounds to me like you need better engineers.
We definitely need better engineers, and I hope that they're
out there in our audience listening today because we have
some engineeringly very challenging projects on the docket. Ye hi,
(01:02):
am orhammy cartoonists and the creator of PhD comments, Hi,
I'm Daniel. I'm a particle physicist, and I'm happy to
put off my problems onto engineers, even your personal problems.
There does seem to be a proliferation of engineers. You know,
back in the day that was mechanical electric. You make
it sound like we're a pest or, but you know,
now you've got the software engineers, you've got social engineers,
(01:25):
You've got every kind of engineer. It's crazy. So yeah,
maybe Daniel's personal problem engineers, I supposed to physicists who
there's only one kind. There are only a few of us. Yeah,
that's true. There's like solid state matter, wet matter, dark matter.
It's been a while since we invented a new kind
of physicist. Yah, maybe it's time. Maybe it's time. Yeah,
(01:46):
Daniel's personal problem physicists. I don't think any of my
personal problems can be solved with physics. That there's learnal
laws there to be found. But welcome to our podcast.
Daniel and Jorge explained the Universe State production of Hard Radio,
in which we focus on the questions that can be answered,
the questions that might one day in the future be answered,
(02:07):
questions about how the world works, about what the universe
is like, how it will end, and how it is
put together on the smallest scale. Yeah, we love questions,
and we love questions for which we know the answers
and we know the question. We love the also questions
for which we don't know the answers, because there are
still a lot of questions out there in the universe
that nobody knows the answer to, and often on this
(02:30):
podcast we take a tour of some of those questions.
We show you what's in the mind of scientists at
the forefront of knowledge is they try to peel back
a layer of reality and expose the universe as it
really is. And sometimes we take you on a tour
of the minds of our listeners, thinking about what everybody
out there is wondering about. Yeah, and we love taking
(02:51):
lists questions from listeners because they really sort of give
us an insight into what people are thinking and what
they're what our podcast is kind of make them think about.
That's right, and not just because they give us sort
of like a checkpoint so that we understand what listeners
are getting and what they're confused about. But sometimes listeners
questions really put their finger on something amazing about the universe.
(03:13):
When I teach, you know, freshman physics here you see Irvine,
it's when they ask a question that it makes me
think about a topic in a new way, makes me
explain in a new way, and then it really makes
me understand it. So listener questions are really a source
of insight. Yeah, And let's face it, we have I
think the best listeners in the universe Daniel Podcast on Earth,
(03:35):
and I would say in anywhere else in the universe,
I think we have the best listeners. That's right, And
we're talking specifically about you. You know who you are.
We're talking about you right there listening to us right now.
You're the best. You're our favorite listen. You're the best looking,
you smell great today, and you ask awesome questions and
tell my kids that all the time. I'm like, you're
my favorite daughter, and she's like, I'm your only daughter
(03:58):
that I know of. Daniel and Jorge dig Into or
his sort of past. Hey, you know, if this is
going to be Daniel and Jorge starting to tell a novella,
then you're going to have some sort of you know,
other family show up at some point in season seven.
My evil twin twins genetically the same. Does that mean
(04:20):
their kids are sort of also like your kids? Boy? Interesting,
he's had a great listener question. Yeah, Or does that
mean if you can have, if you can be twins
and one of you is evil, does that mean that
evil is not genetic? Or maybe you are evil but
you do you don't know it. There are no good twins,
is that what you're saying? Well, they should either both
be good or both be evil. I'm sure that all
(04:42):
the twins listening right now are both good? Well, anyways,
we do have the best listeners and they do ask
the best questions that they send us through Twitter or
Facebook or Instagram or by email. And if you're out
there listening to this podcast and you have a question
about the universe, you can also write it to us
and we will eventually get to it on the podcast.
(05:02):
That's right, And we answer all of our listener emails
pretty promptly. Sometimes people writing asking a good physics questions.
Sometimes people writing asking sort of off the wall questions. Uh,
nobody so far is asking for marriage advice. But here's
a question we got last week which sort of made
me chuckle. It's from Gridget saying and here's what he
had to say. He wrote, if we assume the world
(05:25):
is a simulation, do you think there's only one conscious
being and the rest of the world are just biological zombies?
Or everyone is conscious? I love this question. It's like
am I playing a video game? Or are we all
playing a video game together? It's like are you a
non player? Yeah? Yeah? Or is there somebody really in there? Interesting? Well,
(05:47):
it just gets to the bottom of consciousness, right, like
kind of machine be conscious, kind of machine be conscious. Yeah,
and maybe this guy spends a lot of time in
video games wondering if those other players are real or not.
But a fun question, but not one that I, you know,
necessarily have any expertise or ability to answer. So I
could pontificate as a physicist, but I think the physicists
(06:09):
spend too much time talking about things outside their area
of expertise. So I'm gonna have to point on that one.
Maybe you've noticed that what if? What if you're playing
a bit of games where you have to kill zombies,
then technically are those zombies? But are those zombies conscious?
But they can't because there's zombies? Yeah, well you could
be committing digital moral crimes. But we love answering listener
(06:32):
questions and sometimes we have episodes where we ask to them,
and so today is what are those episodes? So today
on the program, we'll be tackling listener questions about the universe.
That's right. We'll be touching on exotic matter, will be
building roads that span the Earth, and we'll take our
minds to other galaxies and wondering what life is like
(06:56):
out there aliens. Basically, we're feel I feel like we
can have a listener questions episode without touching the hitting
the alien button. Are you saying that's because our listeners
are fascinated with aliens? Are you suspecting that I'm picking
the alien questions out of the slush pile. I feel
like there's a Van diagram there listener questions and things
(07:19):
Daniel loves to talk about. If you have a question
about anything, dear listeners, just put the word alien in
it and it will increase your chances that we'll talk
about it. That's fair, that's good advice. Yea, I have
a question about dark matter. Just wonder if dark about
her could be made by aliens? And well, I'm sure
we'll consider it. My kids know that already. They're like, hey, Dad,
can I have ten bucks? It's for aliens? Yeah, sure,
(07:41):
here we go. All right, So today we have three
questions from listeners from all around the world, and so
we'll be tackling each of these questions one by one.
And so the first question comes from Maria from Canada
and she has a question about exotic matter. Here's your question. Hi,
Daniel and Jorgey. My name is Maria and I'm a
listen from Victoria, Canada and I was wondering what's exotic matter,
(08:05):
how is it different from dark matter or antimatter? And
how many different kinds of matter even are there? Anyways,
thank you so much, awesome questions. I feel like she's
sort of get throwing little shaded physicists. I felt that,
I felt that shade, like, hey, get this under control,
Like people are ridiculous, Yeah, that this matter naming is
getting out of control. It's we have as many kinds
(08:27):
of matter as there are like fields of engineering, and
that's absurd. We we need a new feel for every
kind of matter you guys come up with. So it's
not our fault. We need exotic physics and exotic physicists.
We're just trying to plug the holes of physicist are creedive.
Thank you, by the way for your tireless work plugging
our holes. We just need to have a lot of
kinds of matter in our universe. There's, for example, baryonic matter, antimatter,
(08:51):
dark matter, exotic matter, supersymmetric matter. Yeah. Yeah, the list
goes on. And this is a totally great question, and
it's a fair question also because this term is used
in lots of different ways. In a very general way,
people use the phrase exotic matter to me literally, just
that like matter that seems kind of weird, like exotic,
(09:11):
something different from the every day you know, the everyday
matter is made of quarks and electrons, and so from
that definition, exotic matter could be like dark matter, you know,
or other weird stuff that's out there. Oh boy, now
you're just making it worse, Daniel. Now you're like overlapping
all these matter designations. We're not great at that. In
(09:31):
particle physics, you know, matter could just be any matter
that is against something. Yeah, it could be. So it's
it's a different opinion. It's a very vague tournament. And
it could even be weird forms of familiar matter. Like
if you take atoms and you cool them down and
make weird quantum states like Bose Einstein condensates, some people
would call that exotic matter. Or if you make super fluids,
(09:54):
you could call that exotic matter. Well, well, let's take
it's a step back here. You're saying that the word
exotic matter is not well defined in physics. Yeah, if
you just google what is exotic matter? For example, you
will see articles physicists discover exotic matter, but then it
turns out it's actually about super fluids, or physicists use
exotic matter to communicate quantum mechanically and then it turns
(10:16):
out it's just bosion stain content. States m hmmm. So
you're saying, just like in our culture, the word exotic
is sort of outdated and inappropriate. Yeah, it's a little bit.
It's been a bit abused. But there is also sort
of a narrower version of exotic matter that has a
very specific, fascinating meeting in particle physics that I think
(10:36):
we could dig into. Oh I see, all right, So
in general, it can just mean any kind of non
normal matter, weird, spooky Halloween matter in the loose sort
of definition of yes, spooky Halloween matter, or you know
matter from the Orient, which is that racist. Yeah yeah, yeah,
(11:00):
extern centric and but um no, you're saying, and in
general sense it just means weird matter. But there's also
sort of maybe a hardcore group of physicists who are like, hey,
this means something very specific. Yeah, they rock out the
heavy metal and they talk about this kind of matter.
They are hardcore, and that's matter with negative mass. So
(11:20):
in particle physics we talk about exotic particles or exotic
matter and what we mean are particles that have negative mass,
Like you know that mass is something we attached to particles,
and I have mass and you have mass, And a
fascinating thing about mass is that it seems to always
be positive. So we've invented this idea. Maybe there are
particles out there with the other kind of mass and
(11:42):
negative kind of mass. Mm hmmm, because right, because mass
is just kind of a label, right, it's not actually
like stuff. It's just kind of a like an electric
charge can be positive or negative. Yeah, we don't really
understand it. And if you zoom down to an individual particle,
particles have no volume. They're just points and base with labels, right,
like electric charges, you said, And mass is another property,
(12:04):
and mass is a property that these particles get from
interaction with the Higgs field. But the fascinating thing about
mass is that it always seems to be positive. Right.
We measure the mass of all of these particles and
we see that they have positive mass, and that has
fascinating consequences because the Higgs field always gives these particles
positive mass, or like the interaction is always positive, like
(12:25):
I has anyone had a bad experience with the Higgs field?
I guess it only has five star reviews on Yelp.
So yeah, in the Higgs field widely loved, would recommend yes,
Higgs field good. Um, But did you know what I mean? Like,
if something has negative masses, that mean that when it
interacts with the Higgs field it gets the negative mass
(12:45):
or what does that mean? Well, if a particle had
negative mass, we don't know how it would get that mass.
One way to get mass is to interact with the
Higgs field. We think there might be other ways for
particles to get mass too, but we've never seen one
like that, So there could be various ways for articles
to get mass. It doesn't just have to be the
Higgs field. The Higgs field just kind of determs how
it moves in the universe. Right, But you can still
(13:08):
have mass independent of the Higgs field. Yes, you can
get mass without getting it from the Higgs field. We
haven't ever done that, but like, we don't know neutrinos,
do they get mass from the Higgs field or not?
Do they get mass in this other weird way And
we can dive into that and a whole other podcast,
But I think the important concept to remember is what
you just said is that it changes how you move
through the universe. Often, when we talk about mass, we
(13:29):
really mean two different things. One is inertia, like you
give something a push. It takes a push to move something,
to change something's momentum, to get it started, takes a push.
We call that inertia. Really, that's mass, right, and that
comes from the formula F equals M. A force is
mass times acceleration. To accelerate something, you have to apply
(13:50):
a force, and the mass is the relationship between those two.
So that's mass. Concept Number one is inertial methods. How
hard it is to push? Yeah, how hard is it
to push to get it going? And also how hard
is it to slow it down? Like a semi truck
has a huge amount of mass, takes a huge force
to slow it down. Can something have negative inertial mass?
Is that possible where you like, you push it and
(14:12):
it goes faster, or you know, like it pushed you
push it and it actually pulls you or something, and
you know what, that's what would happen if you gave
it a push to the left and it had negative
inertial mass, it would move to the right, it would
push you, push you back. Yeah, so the force would
be the opposite direction of the acceleration. So the weird
thing about negative mass is like, it seems weird. It's
(14:33):
totally counterintuitive, but mathematically it kind of hangs together, like
we don't have a reason to believe it doesn't exist.
You could fit it into all of our equations. We've
just never seen an example of it. That kind of
weird example could happen where you like push it one
way with the with the force field or something, but
it goes the other way. Yeah, you could do that
(14:53):
in theory. It's possible. We've never seen it, but you
can work out all the equations of motion and it works.
So you push into the left and it moves to
the right. But that's only one way of thinking about mass.
Is a whole second concept of mass, which is mass
in gravity. Like two objects that have mass feel gravity
and attract each other. So so if something has negative mass,
(15:16):
it could maybe repel another thing, would mass. Yeah, the
fascinating thing about positive mass and gravity is that gravity
is one of the only forces that so far seems
to be just attractive. Right, you get pulled in by
the sun, you get pulled in by the moon. There's
no way, you get pushed by gravity, whereas like electromagnetism,
there's a positive and negativity, and if you have the
(15:37):
same charges you get repelled and gravity it is only
positive and it seems to only be attractive. So if
you add negative mass, then yeah, you could get repulsive gravity.
Or I guess maybe in like the Einstein space bending picture,
it would be sort of bend space the other way. Yeah,
instead of having like a dent down into space, it
(16:00):
would be like a like an explosion of space a
little bit. So things like slide away from you like
a z in space, like a like a bump a space.
Don't pop at ZiT. That's like a gravity bomb. Yeah,
you have a negative experience. Don't do it. It's weird though,
because this is a little counterintuitive. You know that positive
(16:20):
mass of course attracts other positive mass. It would also
attract negative mass, and negative mass would repel negative mass
and also positive masses. Wait what, it wouldn't be like
electrical charges. It's not like electrical charges because you just
said that. We don't think of gravity as a force.
We think as a bending of space. So positive mass
(16:42):
makes like a dent in space like a whole in
space for things to fall into regardless of their mass,
and negative masses make space zits. That was actually Einstein's term,
and is it z it's their spation and now that's
a joke. But a negative mass make these would make
these like you know, or I'm gonna say zits in
(17:04):
space because regardless of the mass of the other thing. Right, So,
positive masses attract other positive or negative masses, and negative
masses repel negative or positive masses. It's like the opposite
of a black hole. Yeah, and it's weirdly sort of asymmetric, right.
(17:24):
You like to think about the forces as being symmetric,
so like it depends on the product of the charges
or something, but it wouldn't be. And that means if
you have like a positive mass and a negative mass
next to each other, then the positive masses pulling on
the negative mass, but the negative mass is pushing on
the positive mass. Um what would happen? They would actually
(17:45):
just like lead to this runaway motion because the positive
masses pulling on the negative the negative is trying to
repel the positive. Attraction of the negative actually pushes the
other direction, right because of negative and inertial mass, And
it would just skip out of town. Let's skip out
of town for real. Well, we don't know, Like this
(18:07):
is the idea, so we've never seen this stuff. It's
just sort of an idea, and and it would be
pretty helpful because if we did have exotic mass, we
could use it to, for example, stabilize wormholes and travel
through the galaxy and this kind of stuff. But we've
never seen any of it. It's just sort of like, yeah,
I guess that's in the lad. The next question, which
is is this even real or is it just theoretical.
(18:29):
It's just theoretical, but it's important to recognize these sort
of theoretical opportunities. Some of these other kinds of matter
we talked about, like antimatter. They started out it's theoretical,
and somebody noticed, hey, the equations also work if you
flip all these signs and make this other weird kind
of matter. So maybe that's real, and it turns out
it's true. So seeing these mathematical symmetries are often guides
(18:51):
actually binding stuff in reality, and that will tell us
more about the universe. Yeah, but the universe is asymmetric sometimes,
like there's a lot of matter out there, very very
little antimatter, if any. We don't know why that is.
So there's a lot of positive matter out there, none
or maybe very little negative matter. Why is that right?
Fascinating questions? Yeah, maybe not all the matter matters. All
(19:15):
matter matters, man, but all right, so, um, it seems
like to answer Maria's question, exotic matter. Um can mean
a lot of things, but it generally it's terribly used
just to me, like not normal matter, meaning the matter
you and I are made out of. It's kind of
weird or unusual. Some physicists call that exotic matter. But
there's also sort of the hardcore definition, which is that
(19:38):
it means matter with negative mass, which is theoretically fascinating,
totally possible, but never been seen. But you know, she
also asked another question, which is how many different kinds
of matter are there? Anyway? And that's such a good question.
It's a question that I have also because we see
these symmetries in nature. We see like, oh, there's matter
and antimatter, there's maybe positive matter and negative mass matter,
(20:02):
and there's other symmetries like we talked about supersymmetry on
this program, like maybe every spin half particle has a
spin one particle that that balances it, and vice versa,
and all these symmetries tell us something deep about the universe,
about the way it's put together, about what it reflects
that its deepest level, And we don't know what the
answers are. But every time we find a symmetry, I
(20:24):
feel like it's revealed something about the universe that we've
been desperate to find out. Every time you find a
new kind of matter or think up but you kind
of matter, it kind of pushes your definition of what
can exist. Yeah, and these symmetries are really important. You know.
We talked also on this program about how the universe
is left handed. It prefers particles that spin in a
(20:45):
certain way relative to their motion. We don't know why
that is, and so people suggested and maybe there's another
kind of matter called mirror matter, where it's the opposite.
And every time you have these symmetries, you have to ask,
why is it this way and not the other way?
Why is the universe sort of by furcated into two options.
What does that mean about the nature of the universe
At some higher temperature earlier in the universe, was this
(21:07):
all unified into something beautiful? And crystalline, and then it's
just sort of cracked and fell apart. We don't know.
I think my favorite kind of matter are the matters
of the heart. Daniel. All right, well, we hope that
answered your question, Maria, thanks so much for asking the question.
And so let's get into our two other questions for
the episode, and these are about the biggest road ever
(21:28):
built and also about intergalactic aliens. But first let's take
a quick break. Alright, we're answering listener questions today. Answer
(21:49):
Our next question comes from Rahul from India, and so
he has a question about an interesting idea for an
infinite road. Here is so, imagine you start building a
bridge or a highway above the surface, and it goes
all the way around the earth and meets each other.
Now you have this one long, continuous bridge. So obviously
(22:11):
those bridges have pillars, and now you decide to bomb
all the pillars that supposed the bridge at the same
exact time. So what would happen to the bridge? Will
it stay floating above the surface or will it fall down?
And at which direction? Or will it hoholla hoop the earth?
And the second condition is what would happen if the
(22:33):
Earth was perfect sphere. So I think this one might
be more in your alley because it's kind of a
question about, you know, whether something is engineeringly possible. You're like,
this is not interesting to me, or hey, you can
take this one. It's just about building a road. Now,
if aliens built a road, that's just positive that. Let's
(22:55):
just let's imagine we're in an alien planet. But the
question is kind of interesting, and I have to say
it took me a second to sort of get it.
So he's he's asking, what if you build a road
all around the Earth, like a suspended road, right, and
it goes you know, from it starts here in California,
goes through the US, crosses the Atlantic, goes over Europe Asia,
(23:18):
and then it comes back around and connects in a
perfect circle to where we started the road. And then
so you build this road, it rings the earth and
then you take out all the columns, the pillars that
supported simultaneously with bombs. Right. I like that detail. Yeah,
that would probably the funnest part actually, But you remove
(23:39):
the pillars, all of a sudden, does the bridge stay
up floating or does it all fall down? Yeah, And
it's a fun question because you imagine you build a road,
you support it with pillars, you knock the pillars down,
the road falls down. But in this scenario, you've made
it go all the way around the earth. And so
then he's wondering, like, is it possible for a road
to float in the air? Would it be in orbit, Daniel?
(24:00):
Would it just be sort of like a pula who
held around your waist. Let's answer this from a physics
point of view, which means we have to like simplify
things a little bit, and then we'll make it a
bit more practical. So first let's start with the let's
hear answer A from Daniel. First, is a perfectly spherical earth,
like very smooth, no deformities, etcetera. And so the road
(24:21):
is like a hundred meters or a hundred feet or
whatever above the surface all the way around the Earth.
Now that scenario you knock out all the pillars. Think
about the gravitational force on this thing. It's going to
be balanced, Like the Earth is pulling on one part
over California, but it's also pulling on another part over China,
and those two things are going to balance. And if
(24:42):
the road really goes all the way around the Earth.
Then for every part of the road there's a counterpart
that's balancing its force, and so it should just hover there.
So that's your answer that it would stay up floating.
If it's a perfectly spherical Earth and a perfectly circular road,
it would stay up there floating. You don't believe it, well, Um,
so I have an engineering answer, but I'll just keep
(25:05):
going with your physics answer here for a bid. The
other way to think about it, it's just by symmetry,
like if it goes in one direction, which direction could
it go? You have to choose a direction, And if
the Earth is a perfect sphere, then there's no preferred direction,
so it can't go in anywhere any direction. So it
would keep rotating with the Earth. It would keep rotating
with the Earth, Yes, but it wouldn't have to rotate either.
What if something knocks it off of alignment a little bit,
(25:28):
Like what if the wind blows an in on one
side of the Earth and not the other, and now
it's a little bit closer to one side than it
is to the other side of the Earth. Yeah, so
we're leaving the world of perfect physics scenario and we're
adding things like wind and disturbances, And you're right that
it would be very unstable because if it moves like
(25:48):
one foot closer to the Earth here, then so I'll
foot further from the Earth on the other side. So
now the force is stronger on this side and weaker
on the other side. So it's unstable. It's when does
it deviates from this sort of like perfect spot it's in,
it's going to come crashing down. Oh, I see it
moves a little bit, and so now let's say it
moves down here in California, so it's closer to the Earth,
(26:11):
and now the center of the mass of the whole
thing is a line with the center of the Earth.
Wouldn't that just make it come back to the center
of the earth realign I'm pretty sure it's unstable. And
the reason is that the mass of the Earth is
distributed as a function of the radius. So you can't
just think of the motion of the center of massive
two objects. These are two large distributed objects, and as
(26:36):
one side of it gets closer to the Earth and
the other side gets further that you're gonna get a
relative force difference on the whole thing that's going to
push it further from stability instead of closer to stability.
But I haven't done the simulations. So maybe we should
actually build this thing and find out to answer the
Rahul's question. Let's spend a trillion dollars. Why not? You
(26:57):
got something better to spend it on. So it sounds
like a plan. Let's crowdsource it. Everybody's send in ten
bucks to build Rahul's road. Okay, So you're saying that
from a physics point of view, it is possible for
this thing to exist if nothing touches it or knocks
it out of bound, or moves it at all a
little bit, it would just float above the earth, certainly
(27:18):
the Earth, like a like a ring, like a hula. Yeah,
And I think the key there is that as soon
as you build something that's the size of the Earth,
you can no longer apply the rules of your intuition
that you apply to things that are the size of you,
or your house or even your city. Right, Like, things
can float up in space in orbit. That seems weird.
Why don't they fall? Right? That's because they're largely moving
(27:40):
at cosmological astronomical speeds. And so here's an object really
of astronomical scale, and so it wouldn't necessarily fall into
the earth. It's like an object that spans both sides
of the Earth, of the center of mass of something big. Yeah,
and this actually appears in a novel. I mean, not
as a road, but in Neil Stevenson's recent novel seventives.
(28:02):
Earth becomes uninhabitable because of X y Z plot devices
that won't spoil, and humanity builds a huge ring around
the Earth, like a mechanical ring, and actually live on it. Well,
that that, I think that's the physic times for I guess,
you know, as an engineer, when I saw this question,
I didn't, you know, sit down and make the calculations,
but I think right away my thought was that no,
it would it would fall apart right away. You mean,
(28:24):
because you couldn't build something that big, that was rigid.
I think I was thinking, you know, the limitations of
whatever you build it out of, you know, would collapse
like nothing. I don't think anything that we know of
can withstand those kinds of forces, and so we just
crack and fall apart. You mean, forces from like an
entire four thousand mile road segment pulling on individual piece. Yeah,
(28:46):
you know, like there's a reason you can't just make
a suspended bridge without any columns. Like if this was possible,
then you could just build a bridge, and if you
make it the curvature of the Earth, then it would
just stay up, wouldn't it if we just hold both ends. Yeah? Well, uh,
not an expert on mechanical engineering, So I'll take your
word for it that I think you're right, And I
think there are also other practical issues also, you know,
(29:08):
like you have to have it at the same height
above the earth all the way around, but of course
there isn't a constant height above the earth. You know,
you have to clear mountains and all sorts of stuff,
and so that would throw the whole thing off balance.
All right, Well, I think that's maybe whose question answer,
which is that it's sort of would be possible, and
it would hang there floating above the earth if nothing
(29:30):
touched it or nothing perturbed it at all, no weather,
and if it was made from like this incredible material
that that would would stand these incredible forces, which um,
I'm not sure we have. That we definitely don't, because
if we did, we could build a space elevator, which
is sort of weird. And similar ways, something hanging out
(29:51):
there in space you can actually climb up. And one
of the limitations there is just building a rope. They
could even hang That's that that is that long? Right? Yeah,
something I can that wouldn't just crack under under all
those forces. It's under but definitely cool and fun to
think about. Thanks for Hull for sending in your crazy question. Alright,
are we ready to talk about aliens? Because I'm ready,
(30:12):
You're always ready, Daniel. All right, let's talk about aliens,
but first let's take a quick break. Al Right. Our
last question comes from Nanu from Argentina, and she has
(30:34):
a question about life from other galaxies. So here's Nanu.
Why wouldn't we talk about life in other planets? Do
we always talk about it in terms of our own galaxy?
Do we not consider life in other galaxies because they're
so far away it would be inconsequential for us. I
still have hard time figuring out distances, So I am
wondering could it be possible for millions of years old
(30:55):
alien race to take up into galactic trouble and arrive
to our own galaxy? All right, Daniel, did you just
get really excited when you opened up your in Boston
saw this question. Your hearts start racing a little bit.
You get excited. I got excited, and then I got
a little offended. You know. She said, what do you mean? Well,
she said, how can we never think about intergalactic aliens?
And I was like, what are you talking about? I
think about intergalactic aliens all the time, and it's one
(31:17):
of my favorite things to think about. I think maybe
she thinks she's talking culturally, the culture and in general
or responsible scientists rarely talk about intergalactic aliens. Yeah, I guess,
and it's that true. Do I guess? Do most people
think of aliens is coming from this galaxy? I think so.
Even in science fiction, often the drama takes place across
(31:39):
the galaxy or in one galaxy. And there's a reason
for that. The reason is that galaxies are huge, right there,
big enough to span enormous space operas and lots of
different empires and thousands and billions of stars. Plus they're
super far apart, so it's like each galaxy is an
island and all the other galaxies they're so far away
(32:01):
they're almost irrelevant. It's almost impossible to think about communications
between galaxies, or to travel between galaxies, or travel between galaxies.
You know, not to mention like intergalactic marriages. You know
all the problems that would raise a long distance I know,
you've got the kids over there for one weekend. I
got the kids over here for another weekend. It's a nightmare.
But let's give them a sense of scale, right, Like
(32:22):
the Milky Way is like a hundred thousand light years across.
That's already like, it's incredibly big. Even if you were
going at the speed of light, it would take you
a hundred thousand years, Yeah, to go from one end
to the other. Yeah, exactly. So it's hard to even
imagine having like an empire that spans the galaxy because
you send people a message like all right, let's raise
(32:43):
taxes one percent, and it doesn't get there for a
hundred thousand years. It's impossible to coordinate. That's why people invent,
you know, faster and light travel and faster than light
communication just to get stuff done within one galaxy in
novels and movies and hopefully one day in reality, but yes,
mostly novels and movies. Yes, you seem to mention it
like because we had, we already have that. People are
(33:05):
working on it. People are working on it. Hey, we
were talking about wormholes a minute ago, right, So yeah,
but you were saying, so the galaxy at typeople of
galaxy is a hundred thousand light years wide, and but
the distance between galaxies is you know, many times that
over by several orders of magnitude. Yeah, like the nearest
(33:26):
galaxies Andromeda, and that's two and a half million light
years away, right, it's and a half million years light
years years. It's twenty five times as why is the
whole galaxy? It's like if you have a house and
the neighbor's house is like, you know, blocks and blocks
away from you. So we're basically living in the middle
of the woods. So maybe that would explain why we
(33:48):
don't see it much in movies and novels because you know,
the plot logistics, which is be too much but um,
and also I think maybe it's also kind of recent.
You know, this idea that there are other galaxies. It's
kind of new, isn't it In the last fifty to
sixty years or something like that. Before that we thought
like our galaxy was it. Yeah, it's about a hundred
years old. It originates with Hubble. He's the guy who
(34:11):
measured how far away these little smudges in the sky
where he thought maybe they were nebula, they were gas clouds.
He measured their distance and found that they were crazy
far away. They were further away than all the other stars.
And that's what made him realize, oh, these are other galaxies,
and the whole universe just became much bigger in his mind.
So you're right. It's but we've had about a hundred
(34:31):
years to get used to this idea that the universe
is incredibly vast, but we haven't sort of mentally populated
it with aliens. And I think you're right. And one
reason is that they're just so far away it seems
almost irrelevant. We may never hear from them, or see
them or visit them. We may never that's true, but
we can still think about them. And I think a
really fun angle on this question is wondering, like is
(34:54):
life more likely to occur in those galaxies or in hours?
Is our galaxy unus usual? The same way we think
about is our solar system unusual in our galaxy? We
can ask is our galaxy unusual in the universe for
us to have developed here or evolved here? Like maybe
um most like maybe all other galaxies are too dangerous
(35:15):
for life to evolved in. Yeah, maybe we're in a
special place, right, or maybe we're in a totally vanilla galaxy,
and so we do know something about that, right. We
know that the Milky Way is a spiral galaxy, and
spiral galaxies are one of the most common kinds of galaxies.
We look out in the sky, we see lots and
lots of spiral galaxies. So there doesn't seem to be
anything particularly weird about our galaxy. It's not the smallest,
(35:37):
it's not the biggest, it's not the brightest or the darkest.
It has dark matter like other galaxies. So it's sort
of a generic galaxy. I mean, I love it. It's beautiful. Um,
I don't mean generic in a bad way. I mean
the generic in a totally vanilla way, by which I
mean that there's possibilities for life in other galaxies the
(35:58):
same way there is here. I wish you may And
it's the example by which all other galaxies are sparring too.
I mean, it's the role model galaxy. It's the exemplary
galaxy excisely, and it means that if there's life here,
there's no reason to believe there couldn't also be life
in those other galaxies? But could we able to find it?
Could we ever communicate with them? Could we ever shake
hands and spend time at a chalkboard, you know, revealing
(36:21):
secrets of the universe together. Oh boy, that's hard to imagine.
But but maybe not that hard to imagine. I mean,
if we can imagine us contacting aliens within this galaxy,
you know, them crossing the large amount of space between
us and them. You know, it's not that hard to
imagine doing that twenty times over to do it between galaxies. Right,
(36:43):
you won't drive an hour down here to Irvine to
hang out with me, but you'll drive twenty hours somewhere.
Is that you're saying. I'm saying if I really wanted
to see you, the difference between one hour and twenty
five hours wouldn't be because if I was an alien,
then you would drive twenty five hours to come back
to me. If it took twenty five seconds to go
see Daniel, I don't know if I still would. Oh no,
(37:06):
it's a good point. Um. You're right that if we're
going to explore our galaxy, we either need to do
it very very slowly, over sillions of years, or figure
out a way to overcome these distances which are already
an obstacle in our galaxy. And once we do that,
then maybe we could also hop to nearby galaxies. Yeah, right,
Like if you invent or you figure out how to
do wormholes or warp draws or suspended animation, what's the
(37:29):
difference between a year and twenty five years to go
to another galaxy? That's true. And you know, while we're
tossing our ridiculous ideas, remember our recent episode about stellar engines.
We could drive the Sun out of the Milky Way
and go visit another galaxy. We could like move galaxies
and go hang out in Andromeda. All right, Well, to
answer no question, I guess the answer is, we don't know.
(37:51):
We don't know why we don't think about any for
another galaxy, but maybe we should because it's not that
far off from aliens in our own galaxy. Yeah, and
it's true, none new that in millions of years, alien
racist could use intergalactic travel to to come here and
tell us all about what it's like to live in
another galaxy. And they'd be like, whoa, this is a
better galaxy. You're right, it has better reviews. I'm yelled.
(38:15):
So thank you to everybody for writing in those amazing questions,
and thank you to everybody else who's writing in questions
on a daily basis. We'll get to your questions as well,
and if you have a question, feel free to send
to us. Daniel likes to sit around and answer questions.
I like to be distracted from my real job by
thinking about your crazy ideas about physics. So thanks for listening.
(38:37):
We hope you enjoyed that. See you next time. If
you still have a question after listening to all these explanations,
please drop us a line. We'd love to hear from you.
You can find us on Facebook, Twitter, and Instagram at
Daniel and Jorge That's one word, or email us at
(38:59):
feed act at Daniel and Jorge dot com. Thanks for listening,
and remember that Daniel and Jorge Explain the Universe is
a production of I Heart Radio. For more podcast from
my Heart Radio, visit the I Heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows. Yeah
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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