Can antimatter help us find dark matter?

Daniel and Kelly look for ways that mysteries of antimatter could shed light on the mysteries of dark matter

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Episode Transcript

Speaker 1 (00:05):
There are so many amazing, colossal mysteries out there, so
many parts of the universe that are hidden from us
that still need to be explained. I mean, you've got
dark matter, you got anti matter, you've got dark energy,
you got exotic matter, you got why anybody ever lives
in Virginia. So many things to figure out. And I've
noticed that lots of people out there, especially those folks

(00:27):
of you who write into me, are drawn to the
idea that some of these mysteries could be connected, that
maybe you could like solve two of them at the
same time. And I totally get why that's appealing, But
usually it doesn't work. Could anti matter be the dark matter? No?
Could dark matter explain dark energy? No? Is dark matter
the reason people live in Virginia? Probably? Also?

Speaker 2 (00:50):
No?

Speaker 1 (00:51):
But sometimes, very rarely there is a chance to connect
two things to help solve a mystery. And that's what
we're gonna do today on the show when we answer
the question could and I matter help us find dark matter?
Welcome to Daniel and Kelly's Extraordinary Universe.

Speaker 3 (01:23):
Hello, I'm Kelly Wiener Smith, and I'm a biologist, and
I'm feeling superior today because at least we know what
parasites are made of.

Speaker 1 (01:32):
Hi, I'm Daniel. I'm a particle physicist, and I'm hoping
that dark matter is somehow made of parasites. So I
can blame Kelly for not figuring it out sooner.

Speaker 3 (01:41):
Oh, we've got to figured out.

Speaker 1 (01:42):
Man.

Speaker 3 (01:42):
If it ends up in our wheelhouse, dark matter will
be solved in no time.

Speaker 1 (01:46):
What about biological dark matter? If you figured all that out?

Speaker 3 (01:49):
Are you talking about poop?

Speaker 1 (01:53):
And there we are, folks, record time from zero to
poop for biologists.

Speaker 3 (01:58):
You know, I'm surprised I made it this long with
the biologist in the room. You do what you can.

Speaker 1 (02:04):
But yes, there's an enormous amount about how our bodies
work and how it makes poop that we don't understand.
So there's dark matter in every field.

Speaker 4 (02:12):
You know.

Speaker 3 (02:12):
I would say we understand it, probably much better than
the dark matter in physics. But I guess your wife
does a lot of biology dark matter experiments, and do
you might say there's a lot we don't know.

Speaker 1 (02:22):
Yes, and she has written grand proposals making that exact
pun as a veiled Pooh reference.

Speaker 3 (02:27):
So I can only imagine how much fun it must
be to study feces. There's a lot of opportunities for jokes.

Speaker 1 (02:35):
That's right. We try to avoid crappy humor, but you
know you can't escape it.

Speaker 3 (02:39):
Oh, it's so great sometimes you need it. All right,
all right, we'll talk about physics dark matter today. How
long do you think before we have that figured out?

Speaker 1 (02:46):
Wow? When are we going to figure out dark matter?
You know, it's incredible because it's been decades that we've
known this is a thing and not understood it. And
the discovery could be any moment. We have lots of
ways we're looking for it that could suddenly reveal something
about dark matter. We could find a dark photon that

(03:07):
communicates the whole new sector of particles. One of the
experiments could actually see a signal, So it could be
any moment. It's really impossible to predict. Or we could
keep looking fruitlessly for a century. The possibilities are really
almost endless. It's impossible to predict. I hope you figured
it out soon before I retire. Perspire and expire.

Speaker 3 (03:28):
Don't exercise too hard, Daniel.

Speaker 1 (03:32):
Perspiration prevents expiration, is my understanding.

Speaker 3 (03:36):
No, that's true, that's true. It's good to perspire subtimes well, today,
we're gonna be talking about a path that might help
us understand dark matter. This is something I had never
thought about before today, which is you know often true
when you send me an outline for our discussions. And
so today you're gonna tell us if antimatter can help
us find dark matter exactly.

Speaker 1 (03:57):
We are going to fall in the chop of trying
to connect two huge mysteries of the universe together, which
is something you see in pop science all the time,
and I get lots of emails from folks trying to
make connections between two different mysteries we presented on the show,
which I love. It means that they're thinking deeply about
the universe and they're trying to put the clues together.
And it's very tempting to imagine that you could like

(04:17):
solve two huge mysteries at once, but it doesn't always
work that way.

Speaker 3 (04:21):
Are there physicists that are working on trying to solve
two mysteries at once or it's just like everyone admits,
it's just not going to be that easy. You know,
when we were talking to Hamas van Reet, I think
he was saying that when you work on string theory,
it pops out other solutions. But I guess that's different
than thinking that two things are connected. It's when you
study one thing and it turns out it explains multiple things.
That's sort of the opposite direction.

Speaker 1 (04:42):
No, that's exactly the right example. That's the feeling you
get when you think, oh, wow, maybe we've uncovered some
corner of the truth because we're working on problem one,
it automatically solves this other problem we weren't even trying
to solve. It tells you that you're making deep connections. So, yeah,
everybody wants that experience because we have this feeling like
there is a true explanation for the universe and if

(05:04):
you just dig deep enough, we'll uncover it and it'll
bring everything together into this glorious moment of insight. But
you know, getting there involves chiseling away patiently at the
rock face of truth and hoping something falls into your lap.
And so what we're going to talk about today is
like one strategy people are using, and I think it's
really cool because it highlights how physicists are doing everything

(05:27):
they can to look for dark matter. We're looking for
it up the wazoo, out the wazoo, to the left
of the wazoo, like really everything we can imagine we
are doing to look for dark matter.

Speaker 3 (05:37):
You've got that wazoo cover.

Speaker 1 (05:38):
Oh yeah, if it's in the wazoo, we'll find it.

Speaker 3 (05:42):
I think it's possible you're looking at the wrong spot,
but I hope that you find it. So anti matter
and dark matter, these are two concepts that I think
most people don't understand at all. So let's see what
our audience thinks about anti matter helping us understand dark matter.
What did they have to say about what insights we
might be covering today and if you would like to
share your insights with us, email us at questions at

(06:05):
Daniel and Kelly dot org.

Speaker 1 (06:06):
So I wrote to people and I asked them can
antimatter help us find dark matter? Here's what people had
to say. As far as I know, dark matter only
interacts with gravitational and with antimatter and matter. Both interacting
with gravitation will force the same. As far as we
can tell, dark matter we don't think interacts with matter,

(06:29):
so it should not interact with antimatter.

Speaker 2 (06:33):
Since we don't really understand much about dark matter, the
only thing we could observe is gravity, so perhaps we
can't detect antimatter, but gravity would be the same for
matter versus antimatter. Maybe that could be an explanation is
why we can't see it.

Speaker 4 (06:49):
Since antimatter tends to annihilate when it interacts with other matter,
then maybe any sort of photon urse might represent interacting
with dark matter if we don't think that there's any
major amounts of regular matter in that area.

Speaker 3 (07:05):
So I was happy to see that most of the
answers pretty much matched what I thought, which was I
don't see how, but you are going to shine that
light for us.

Speaker 1 (07:17):
I am going to make a connection between dark matter
and antimatter. And these are great answers, by the way,
and they're right. Matter and antimatter annihilate, but that is
not helpful for dark matter. Dark matter might only interact gravitationally,
so it'd be difficult to find dark matter doesn't interact
with antimatter any differently than it interacts with matter. So
these are great answers and right on the money.

Speaker 3 (07:38):
Definitely great answers, and I should say it expressed a
lot more physics knowledge than I have. Most of those answers.
So let's start with what do we know about what
dark matter is. You just gave us some hints about
what it is and what it isn't, But let's pretend
you didn't say any of that. Start from the beginning
for the neophyts of us, the dark matter neophyts.

Speaker 1 (07:55):
So dark matter is amazing because we simultaneously know an
annoys amount about it and yet we know very little
about it. It's sort of paradoxical, like we cannot see
dark matter. It's something that's in the universe. It's not
actually dark. It's invisible. So the name already is confusing.
Like when you see dark matter on TV shows, you know,

(08:17):
spaceship is flying through a cloud of dark matter. They
show it as dark like black, like it's obscuring your view.
But in reality, dark matter is there, but it's invisible.
It's transparent, and that's because light passes through It doesn't
interact with it the way light passes through glass, but
even less so, like glass will refract light, but dark

(08:37):
matter doesn't refract light, though it actually can bend it
and lends it a little bit. We'll talk about that
in a minute. But dark matter is more than just invisible.
It's also intangible, like if you were in a cloud
of dark matter you wouldn't even notice you like pass
right through it. Dark matter can like phase through walls
without interacting at all. So it's this mysterious but sort

(08:58):
of omnipresent substance that it's also overwhelmingly dominant form of
matter in the universe. Like eighty percent of the matter
in the universe is dark matter. It's not weird or rare.
In fact, we are the weird and rare kind of
matter in the universe.

Speaker 3 (09:15):
Okay, so it's the dominant matter in the universe, but
we can't see it or measure it, So how do
we know that it exists at all?

Speaker 1 (09:22):
Yeah, so very mysterious. We don't know what it's made
out of. We only learned about it recently, and yet
we know a lot about it because we have detected
its contributions to the gravity of our universe in many ways.
And this is something I really want to underscore carefully,
because a lot of people think dark matter is like
a fudge factor, just something we add to the equations
and don't understand just because things aren't working out. But

(09:44):
dark matter is much more like this suspect in a
mystery novel. Do we know a lot about but we
haven't yet fingered. We know somebody slipped the knife into
the corpse at some point. We see the footprints, we
see the broken window. We have fingerprints, you know, we
have DNA samples. We just haven't found the suspect yet.
And so dark matter is like that.

Speaker 3 (10:05):
I'm not a big fan of dark matter after that description.
It doesn't seem like a nice thing. But it helps
by holding everything together. Is that right? So I shouldn't
be so negative.

Speaker 1 (10:13):
Yeah, No, dark matter is much more helpful than a murderer.

Speaker 3 (10:16):
That's good. That's good. I mean it's a low bar,
but that's good.

Speaker 1 (10:18):
So let's talk about how we know that dark matter
is there and what we know about it, because it
paints a very comprehensive picture of dark matter. So classically
we know about dark matter originally because of how galaxies rotate.
Galaxies are a bunch of stars, but they're also spinning,
and when things spin, they tend to lose stuff. Like
if you put a bunch of ping pong balls on
a Merry go round and you spin it, you don't

(10:40):
keep all the ping pong balls. They fly out. Because
things tend to move in straight lines unless they're being
bent into a curve, Like the reason the Moon stays
in orbit around the Earth is because gravity is holding
it in. So you can do this calculation and ask, well,
is there enough gravity in the galaxy to hold all
those stars in as we spin around at this crazy
high speed. You add up all the mass from all

(11:01):
the stars and the answer is no, and not even
close by the way, galaxies are spending way too fast
to hold the stars in, and yet they're not throwing
stars out into interstellar space. Very often it does happen.
But to provide enough gravity to hold the galaxy together,
you have to take all the mass of all the
visible stuff and multiply it by four or five. So
there's a huge amount of unaccounted for gravity. Right. The

(11:24):
gravity is there, it's holding the stars together. We don't
know what's providing it. That's the original evidence we have
for dark matter, and that's the one that makes people
feel like, oh, it's just a fudge factor. You're just
adding in a number to describe what you're seeing. You
don't really understand it because that's just one piece of evidence.
But we have like many more pieces of evidence as well.

Speaker 3 (11:43):
And also I feel like if it was just a
fudge factor. Then it wouldn't be like times four. Yeah,
it would be like you know.

Speaker 1 (11:49):
Plus five exactly. It's not a little tweak, right, it's
a total revolution in our understanding of what the universe
is made out of.

Speaker 3 (11:57):
Yeah. So, like you're saying, even if we discovered another
Jupiter in our solar system, that still wouldn't explain.

Speaker 1 (12:03):
No, you've got to discover five more hidden stars in
our solar system to multiply the mass of our solar
system by five. Jupiter is nothing in our solar system.

Speaker 3 (12:12):
Yeah, okay, got it, all right, So you've told us
about one piece of evidence. You're assuring us that there's more.
What have been our most promising routes of research to
try to discover what it is that have failed so far.

Speaker 1 (12:24):
Well, we've looked for dark matter in several ways. Essentially,
we assume dark matter is some kind of particle and
we look to see if it interacts with our kind
of matter in any way. So, for example, we have
huge underground tanks of stuff like liquid xenon, and liquid
xenon is very quiet, it doesn't like to interact. This
stuff is underground, so no cosmic rays get to it. Basically,

(12:45):
you have a big tank of liquid xenon and cameras
in there. You say, do you ever see a flash
of light? I mean, you shouldn't see any flashes of light.
But if dark matter, which could penetrate through all of
the Earth and make it to your tank of xenon,
occasionally does bump into your xenon and give it a push,
you'll see a flash of light as that xenon relaxes.
So you have your cameras underground on liquid xenon and

(13:07):
look for flashes of light. It's a crazy experiment, but
nobody's ever seen anything beyond what you expect from like
background radiation from the rocks and all this sort of stuff.
So quiet experiments looking for dark matter bumps haven't seen anything.
We've tried to make dark matter in the laboratory at
the large had Drunk collider. We can smash particles together
and make new kinds of stuff. If dark matter has

(13:29):
any kind of interaction with protons at all beyond gravity, right,
this should require some non gravitational interaction. We should be
able to make it at the large a dron collider,
and then it would appear as invisible particles. We can
tell when we made invisible particles with the Large Hadron
Collider because there's like something on one side of the
detector and nothing on the other side, so there's an imbalance.
But we've never seen an unexplained imbalance of particles.

Speaker 3 (13:52):
Did we expect that we would when we started the
large Head Droun Collider.

Speaker 1 (13:56):
We hoped, so. I was actually one of the people
really working deeply on this topic. A lot of my
grattudents have like a written phddcs on searching for dark
matter with the Large Hyde Drunk Colider. I was really
hopeful because colliders are so powerful you don't have to
know what you're looking for, how to make it very
general search for like what the universe can do. But

(14:16):
we didn't see anything, and you know, hey, that's research, it's.

Speaker 3 (14:19):
Exploration, not the right wazoo.

Speaker 1 (14:21):
Yeah exactly. And there's one other avenue for looking for
dark matter, but let's save that related because that's our
antimatter connection, Okay. And I want to remind people about
how else we know that dark matter is really a thing,
and not just like, hey, let's multiply gravity by four
and we see its effects all over the place, not
just within galaxies, but between galaxies. Like dark matter is

(14:41):
not as clumpy as normal matter. It feels gravity, but
it's not sticky, so it doesn't stick together. Like two
blobs of dark matter, if they run into each other,
they just pass right through each other, whereas two blobs
of normal matter tend to stick together. So you get
like asteroids and planets forming out of matter, but you
don't get planetary structures forming out of dark matter. It's
like a big foamy fluff that fills the universe. It

(15:04):
has places where it's denser in places where it's less dense,
but it's much less clumpy than normal matter. So it
extends out between the galaxies, for example, and it helps
hold galaxy clusters together. Like we cannot explain using just
stars in their gravity why galaxies orbit each other the
way they do, and why galaxy clusters form. You need

(15:24):
dark matter to explain that too.

Speaker 3 (15:26):
And you can tell that dark matter is clumpy based
on the activity of galaxies. Is that right?

Speaker 1 (15:32):
Oh, great question. Yeah, we can tell where the dark
matter is based on the gravitational motion within a galaxy
and also between galaxies. Like we don't just take matter
and multiply by four. We can tell where in the galaxy.
That matter is based on the speed of the stars
at different distances from the center of the galaxy. Like
if you put all the dark matter at the very

(15:52):
center of the galaxy, then all the stars would be
feeling more gravity and it'd all be going really really fast.
If you take some of the dark man, you spread
it out, then it doesn't speed up the stars that
are closer into the galaxy. So by seeing how the
velocity of stars varies from the center to the edge
of the galaxy, you can tell where in the galaxy
it is, and the same thing applies for between the galaxies.

(16:15):
By seeing velocities of all these galaxies, you can make
a map of where the dark matter is between the galaxies.
And you can also see where the dark matter is
because of its lensing. I said earlier that dark matter
is kind of light glass, but it doesn't refract light,
but it does bend light because dark matter is matter,
and matter curves space, and curved space will curve the

(16:38):
path of photons. So if you have a huge blob
of dark matter between us and some other galaxy, it's
gonna lens that light, just like as if there was
some huge lens in space, and we see this in
the night sky, like we see sometimes two copies of
a single galaxy because it's light which shot out in
two different directions got then focused by some dark matter

(17:00):
lens back towards the Earth, so it looks like the
same galaxy, but it's not. It's a duplication. It's an
optical effect. And you can use this to map out
where the dark matter is in the universe by seeing
how the much lensing there is in various locations, So
we can tell where the dark matter is.

Speaker 3 (17:18):
What kind of shape does it take? Does it say like,
oh got you physicists.

Speaker 1 (17:23):
It's a big middle finger, that's right.

Speaker 3 (17:26):
Yeah, it's just lumpy and kind of amorphis it's a.

Speaker 1 (17:28):
Big cosmic poop. Basically, it's a big lump of no.
We can make a map and it's really fascinating, maybe
not surprising. The map of where the dark matter is
in the universe closely follows the map of where matter
is in the universe. It's kind of like luminous matter
stars are a tracer that tell you where the dark
matter is. And it's not a coincidence the luminous matter

(17:49):
the stars, the galaxies are there because the dark matter
is there. So origin of the universe, things are pretty
spread out, but there's little spots that are denser and
little spots that are less dense quantum fluctuations, and so
dark matter where it is denser, it started to gather together.
A little bit doesn't stick, but still it gathers together
a little bit and orbits itself and makes these big swirls,

(18:10):
and that makes it like a gravitational well. And the
other matter, gas and dust, normal matter falls into that
well and gets trapped and forms galaxies and forms stars.
And you can run simulations. If you run the universe
without any dark matter, you don't get galaxies ten billion
or twelve or fourteen billion years after the Big Bang,
You just don't. It takes much much longer. So the

(18:33):
only reason we have galaxies today is because dark matter
has gathered together the gas in the dust and forced
it to make stars and all this kind of stuff.
So we know that dark matter has played a huge
role in the evolution of what we call large scale
structure in the universe. Basically, the reason the universe looks
the way it is is because of.

Speaker 3 (18:53):
Dark matter, and that interaction doesn't work both ways, right,
Like dark matter can pull objects towards it. But like
the Sun isn't pulling dark matter in because dark matter
doesn't respond to stuff.

Speaker 1 (19:03):
The Sun is pulling dark matter in because dark matter
does feel gravity. But what happens when the Sun pulls
dark matter in? You're a blob of dark matter. You
get pulled towards the sun. Cool gravity is pulling you in.
You're going faster and faster and faster. Now, if you're
a comet, you hit the Sun, you vaporize, you interact electromagnetically, hadronically,
all the other kinds of interactions, like you become part

(19:25):
of the Sun. If you're a blob of dark matter,
you're a dark matter comet. What happens when you hit
the Sun? Nothing? You go right through it the same
way like if you dropped a ball through a hole
a tunnel that went all the way through the Earth,
what would happen. It would go all the way through
the center and come out the other side the same way.
Dark matter doesn't stick to the Sun. It passes right
through the Sun and goes out the other side. That's

(19:47):
why dark matter doesn't clump the way that normal matter does.
But it definitely does feel gravity. We have lots of
other reasons to believe that dark matter is there. Like,
we can tackle the problem from the other direction. Some
people are like, well, maybe you're just missing some of
the matter, Like are there just like big blobs of
matter out there you're not seeing, you know, could you
see a huge rock out in the middle between galaxies?

(20:08):
And so people have tackled the problem in this super
amazing way. From that direction, we're able to calculate how
much normal matter there is in the universe based on
what happened in the first few minutes of the Big Bang.

Speaker 3 (20:20):
Wow.

Speaker 1 (20:20):
Yeah, it's really incredible. We look at the distribution of
elements in the universe, how much hydrogen, how much helium,
how much lithium, et cetera, And those amounts are really
sensitive to the density of normal matter in the early universe.
Like the denser it was, the more you're going to
get fusion in the early universe to make those heavier elements,
and the less dense it was, the less likely you are.

(20:41):
So it's very sensitive, Like we can measure exactly what
the density of quarks and protons and all those kind
of normal matter bits were in the early universe by
measuring how much lithium is out there in space, and
so we can tell how much stuff there was very precisely,
and it very well matches the normal matter we see
in the universe. So that tells us like, yeah, there

(21:01):
could be a rock in the middle of space that
we didn't see, even like one the size of Jupiter
or a star, but there's definitely not a huge amount,
not four times the amount of normal matter missing. So
we sort of like accounted for this problem in two
different directions and it all adds up. And then the
sort of coup de grad the thing that like really
links it together is we can look at the very

(21:22):
very early universe. We see ripples from the plasma of
the very early universe. This it's called the cosmic microwave
background radiation.

Speaker 3 (21:29):
Is this the thing that we thought was pigeon poop?

Speaker 1 (21:31):
I'm that's really important exactly. Okay, This is discovered in
the sixties and it's evidence that the universe was once
much more dense. It was this hot, frothing plasma that
filled the whole universe, and it glowed, and there was
a moment when that plasma cooled and suddenly became transparent,
so that glow instead of getting constantly reabsorbed by itself,
the way like light inside the sun is getting absorbed

(21:53):
by the sun and we're only seeing light from the surface.
That plasma in the early universe became transparent, and so
that glow stuck and we can see that glow and
we can tell stuff about that plasma, and most importantly,
we see ripples in that plasma. It's not just like
a constant glow. It's like brighter here and darker there,
and those ripples depend on how that plasma is sloshing around,

(22:16):
and how the plasma slashes around depends on like, well,
how much dark matter is there holding stuff together with
its gravity, how many photons are there pushing things apart
because of the glow, how much normal matter is there
which feels the photons and the gravity. It's like this
complex dance of all the different ingredients of the universe
at that time, and those very specifically control all of

(22:36):
those wiggles. So by measuring those wiggles, we can nail
down exactly how much matter was there, how much dark
matter was there, how many photons were there, and it
all aligns up with our other calculations. So we have
like all these different pieces of evidence that tell us
how much of the universe is normal matter, how much
of the universe is this weird, unexplained gravitationally feeling otherwise

(22:58):
totally intangible kind of matter we call dark matter. So like, yeah,
we got a lot of clues, you just haven't yet
found the murderer.

Speaker 3 (23:05):
So we've tried to see if it's a particle. No
evidence for that yet. We don't know if it could
do anything other than like gravitate and pull things in
towards it or respond to the gravity of other things.
But when we get back from the break, you're going
to bring us to the next big unknown, which is
anti matter, and we'll talk about what we don't know
about that, all right, So in the last segment, you

(23:43):
convinced me that dark matter is probably not just because
someone forgot to carry a five or something like that.
So now let's move on to anti matter, which is
the other thing that we need to understand to answer
the question what can antimatter tell us about dark matter?

Speaker 1 (23:56):
Right, so forget everything we said about dark matter for now,
we're gonna talk about a completely separate topic in particle physics,
which is the mystery of anti matter. And then later
on we're going to connect these. But antimatter is amazing
and wonderful and real. It's like something we see, something
we make, something we study. It's like very pedestrian. In

(24:17):
the collider I used to work on before the Large
Hatener Collider, we collided matter and antimatter. We made protons
and we made anti protons. We smashed them together many
many times a second. So antimatter is not nearly as
mysterious as dark matter. We know what it is, we
know it's a particle. We can make it, we can
play with it, we build stuff out of it. It's
amazing in science fiction y, but it's much less theoretical

(24:40):
than dark matter.

Speaker 3 (24:41):
Okay, you sounded a little bit defensive when we said
antimatter is real, but I guess you were just trying
to clarify that we've actually seen them.

Speaker 1 (24:48):
Was I protesting too much? Well, I think some people
are confused because they read about it in science fiction.
It seems sort of like bizarre and mystical, but it's
actually something we play with all the time in real physics.
It's also just kind of a name we give things
that reveals something deep about the universe, which is that
the universe has these beautiful symmetries. Like basically, antimatter is

(25:10):
a statement that every particle out there has a partner.
So you have an electron, it's a particle, it has
negative charge. There's another version of that particle, the positively
charged version. You have a muon it's negatively charged. There's
a positively charged version of that. You have a quirk
with charge two thirds. There's a negative two thirds charged

(25:30):
version of that. Whatever the universe can do when it
makes a charged particle, it can also do something very
similar with the opposite charge. So it's actually this kind
of beautiful symmetry in the matter that we see out
there in the universe.

Speaker 3 (25:42):
I'm kind of feeling like we should have saved this
topic for the Valentine's Day. It feels a little loveyw
but okay, all right, good to note the universe has symmetry.

Speaker 1 (25:51):
Well, they have a very explosive relationship, because what happens
when an electron and positiron meet is they don't live
happily ever after they annihilate. And popular science tells you
that annihilating into pure energy. Really what happens is they
annihilate into a photon, which and a photon is nothing
but energy, that's true, but it's not this like abstract
form of energy. It's like it's another kind of field

(26:12):
that's rippling and making us a particle.

Speaker 3 (26:14):
All right, Well, it's just some parasites get divorced too.
So I'm seeing connections here, and.

Speaker 1 (26:19):
This is just an example of the kinds of symmetries
we see in the universe. We notice that it's not
just like forty two different particles and they're all different.
There are relationships between them, There are patterns between them,
and often the patterns work in just this way. There's
like several versions of the same particle. So there's an
electron and there's the positron, which is just like the
opposite version of the electron. Don't think of them as

(26:41):
separate particles. Think of them as two halves of the
same coin. But the electron is also one half of
other kinds of coins. For example, the electron has another version,
the muon. The muon is the same as the electron,
just heavier. The tao is just the same as the muon,
and the electron even heavier.

Speaker 3 (26:57):
I feel like the coin analogy is breaking down. Yes,
we're talking about dungeons and dragons, dice or something.

Speaker 1 (27:03):
And we think that the electron participates in even other symmetries.
This this whole theory called supersymmetry, which says that every
particle has this weird partner particle. So the electron would
have the selectron, and quirks would have the squarks, and
we haven't discovered those. We don't know if it's true,
but it's sort of a theme in particle physics that
every particle has reflections, other copies of itself.

Speaker 3 (27:24):
This might be the first time where I've thought, oh,
physicists are doing a good job with naming something though,
because like the squirks, that's both cute and it sort
of tells you what it is, you know.

Speaker 1 (27:32):
Yeah, yeah, I like the supersymmetric names. And it's also
kind of arbitrary, like what is matter and what is antimatter? Well,
the universe is very symmetric. The laws of physics are
almost the same for matter and antimatter, so they are
opposite each other in the sense they have opposite charges.
But it's not like antimatter is like against building stuff.
You could build a universe out of antimatter.

Speaker 3 (27:53):
We think, but antimatter is the rare thing that we
don't see a lot of, right, and so what causes
that asymmetry? There?

Speaker 1 (27:59):
Boy? Do I wish I had the answer to that question,
because I would be talking to the King of Sweden,
shaking their hand and getting a million dollars. Nobody knows.

Speaker 3 (28:07):
Would you still podcast if you got the Nobel Prize?

Speaker 1 (28:09):
Of course, absolutely, I podcast more often. Absolutely nice.

Speaker 3 (28:13):
You'd remember the little people.

Speaker 1 (28:16):
Oh, you're the little people right as you sit in
front of your shelf of awards over there.

Speaker 3 (28:22):
The shelf is out of the screen.

Speaker 1 (28:24):
Huh. If you won the Nobel Prize, your biggest problem
would be like where to put it on your shelf
otherwise crowded with prizes.

Speaker 3 (28:31):
Oh you're making me feel really nice, but that's definitely
over selling. But thank you.

Speaker 1 (28:35):
But you're right. It is a big mystery because if
it's true that the universe treats matter and anti matter
the same way, why are we made of matter? Why
is the Earth made of matter? The galaxy made of matter?
We think most of the galaxies near us are made
of matter. That's an asymmetry, and that doesn't seem to
add up because if the universe made the same amount
of matter and antimatter in the very beginning, when it

(28:56):
was filled with frothing energy which is then cooled into
these fields. Then that matter and antimatter would annihilate. And
that's mostly what happened when we made matter in antimatter
in the early universe. In annihilated and the universe was
mostly filled with photons for a little while, which must
have been brilliant. But there was a little bit left
over because there wasn't a perfect symmetry between the matter

(29:16):
and antimatter, and we don't know why. We don't know
was there more matter made in the early universe or
is there some process in the universe that produces matter
more than antimatter. There's definitely some asymmetry there because, as
you say, there's more matter and less antimatter. But I
also just want to emphasize like antimatter, we name it
antimatter because it's the one that's not made as often,

(29:39):
not because it's against anything.

Speaker 3 (29:42):
You said that we don't know of universes that are
made of antimatter. Could there be universes of antimatter or
like a chunk of antimatter out in the galaxies or
whatever that we haven't seen yet.

Speaker 1 (29:52):
Yeah, it's tempting to say, oh, let's look up at
the night sky. We see galaxies out there. How do
we know they're not made of antimatter because antimatter would
produce photons a way it matter does. And that's true.
But we can tell if some of those galaxies are
made of matter and antimatter, because galaxies don't just produce photons,
they also produce charged particles, like the Sun produces lots

(30:12):
of photons you can see it, but also lots of
protons and electrons, and so antimatter is much rarer. In
our solar wind we are shooting matter out into the universe.
And if a neighboring galaxy was shooting antimatter out into
the universe the same way as you would expect, then
between them there would be this like ribbon of collisions,

(30:32):
this like interface where our solar or galactic winds were
hitting their solar galactic winds and annihilating and making these
bright flashes.

Speaker 3 (30:39):
I bet that would look awesome.

Speaker 1 (30:41):
It would be amazing. I hope it's real when we've
looked for that and we haven't seen it, which means
either the whole universe is just matter, or if there
are anti matter galaxies, they're too far away for us
to see. Now, that doesn't rule out that, like we
live in a vast pocket of matter ninety billion light
years across and be on the edge of the observable universe,

(31:01):
there are vast pockets of antimatter. Maybe even most of
the universe is antimatter for all we know. But in
the region we can see, we can't spot any antimatter galaxies,
and we can't spot any interface between matter and antimatter.
So as far as we know, the universe is mostly matter.
And we've been studying anti matter for a long time,
and so we have some ideas for like what might

(31:22):
explain this asymmetry. We found some ways that the universe
prefers to make matter over antimatter. There's some like little
particle physics processes which if you run them forward in time,
will make more matter than antimatter, but they're very small effects.
They go under the name of CP violation. We can
dig into that in another episode maybe, And so we
have found some ways that the universe is not symmetric

(31:43):
and prefers matter, but it doesn't explain it, Like if
we run our models and you start from a perfectly
symmetric universe, you don't get the huge asymmetry that we
see today. You just can explain a little bit. So
there's definitely a big mystery out there that remains. We
cannot figure out yet why the universe seems to be
filled with matter and not antimatter. And you know, there

(32:03):
are some intriguing clues out there, like some particles don't
have antiparticles, Like you know, the electron has the antiparticle,
the positron, what's the antiparticle of the photon. The photon
doesn't have a charge, so you flip its charge, you
just get a photon. So some people say the photon
is its own antimatter, or another way to say that
is that there is no antiparticle.

Speaker 3 (32:24):
Is that the only particle we know of that doesn't
have an antiparticle.

Speaker 1 (32:28):
No, there's a few, like the z boson, which is
the equivalent of the photon, but for the weak force
that doesn't have an antiparticle. It's also doesn't have a charge.
The Higgs boson has no electric charge. There's no anti
Higgs boson. And something we still don't know is whether
neutrinos are their own antiparticle or not. Neutrinos have no
electric charge, but they do have a weak charge. We

(32:50):
talked about that recently on the podcast and you can
flip those. We don't even know if anti neutrinos are
actually different or if they're just neutrinos. We still have
to figure that out. Neutrinos are so difficult to do
experiments with that it's very tricky to understand their behavior,
and so there's a lot we still have to learn
about what antimatter is. But we can make it in
the lab. We have these amazing experiments we've done at

(33:11):
CERN where we've built like anti hydrogen, where you have
an anti proton and an anti electron you get them
to bind together to make hydrogen and to emit light,
and so we can study in detail does antimatter actually
follow the same laws of physics so far it does.
They did this incredible experiment recently to try to answer
what sounds like a dumb question but turns out to

(33:33):
be a really deep question, which is does antimatter fall
up or down in a gravitational field? Yeah, I see
you going, oh oh, wait a second, I don't know
the answer to that because On one hand, you think, oh,
it's a kind of matter. Matter falls down in a
gravitational field. It attracts, right, But that's assuming that it
feels gravity the same way. And gravity is not something

(33:53):
we fundamentally understand. According to Einstein, it shouldn't matter. But
we think Einstein's probably wrong when it comes to the
gravity of particles. And wouldn't it be amazing if antimatter
fell up? Yeah, and it might be amazing to you
that we don't know the answer to this question already.
And the reason is that gravity is super duper weak
and antimatter we can make it, but it's hard to
make large quantities of it, and you really need like

(34:16):
a large quantity of something in order to study its gravity.
We've never measured the gravity of a single particle. The
smallest thing we've ever measured the gravity of is like milligrams,
which is huge number of particles. So they're doing these
experiments to try to isolate every other kind of force
on these anti hydrogen molecules to see can we see

(34:36):
them falling up or can we see them falling down?
And initial bindings suggests that antimatter falls down, which is
kind of a bummer. Because boy, wouldn't that be cool?
And then we could make our hoverboards finally, and all
sorts of stuff. I know, I know, I've been promising
kids hoverboards for years and have not delivered. Terrible physicists.

Speaker 3 (34:56):
Wouldn't a hoverboard made of antimatter just like vaporize or
explosively combust when you jump on it.

Speaker 1 (35:02):
No, you need to isolate the anti matter underneath somehow
to provide that levitation in a magnetic bottle. I mean,
there's some engineering details that other people would figure out
once we have the essential bits understood.

Speaker 3 (35:14):
We've got a symmetry question for you. So some particles
have a symmetric partner in some dome. If tomorrow someone
was to say, Okay, have this new particle that we've
never heard of before, could you predict if it would
have a partner or not? Do we understand when you
get partners or not?

Speaker 1 (35:33):
I would say, if it has a charge, then it's
going to have a partner, because that's an inherent property
of a quantum field. Like the reason the electron has
the partner is because the electrons field can wiggle in
a way to make an electron and the things that
allow it to do that wiggle also allowed to do
the opposite wiggle to make the anti electron. So electrons
and anti electrons are wiggles in the same field. So

(35:55):
if you discover the Kelly on, Okay, now there's a
Kelly field in the universe. If it can make a Kelly,
then it can make an anti Kelly.

Speaker 3 (36:02):
I think we should name it Wienersmith because that's more
distinctive and funnier. But anyway, I like where you're going
with this.

Speaker 1 (36:08):
But another question is if you discover a new field
with two particles one's positive and one's negative, which one
do you call the matter and which one do you
call the antimatter? That's kind of arbitrary. There's nothing mattery
about one or the other except do you find more
of it in the universe. Right, So, like you could
flip those definitions, and you can flip them arbitrarily. You

(36:29):
could keep the electron as matter and the anti electrons antimatter.
You could say, well, from you ons, we're gonna call
the anti muon matter now, and it makes no difference. Right,
So there's sort of arbitrary labels. So whether the Wienersmith
boson or the anti Wiennersmith boson, is the matter or
antimatter it matters?

Speaker 3 (36:47):
Not? Oh man, We've had wazoos and dark matter and
Wienersmith bosons. This is maybe the best episode we've ever done.
And on that note, let's take a break and when
we get back we will answer the question can anti
matter help us find dark matter? All right, we're back.

(37:20):
So this is an episode of Daniel and Kelly's Extraordinary Universe.
So I'm guessing the answer to can anti matter help
us find dark matter? Is going to be something like maybe?
But I love that as an answer. It's at least
informative and honest. So let's see what is the answer
going to be today? Where do we start with this? Daniel?

Speaker 1 (37:37):
Yeah, the answer is maybe. And it's an example of like, hey,
physicists trying to be clever and finding any possible way
to observe dark matter, and everything we're doing to find
dark matter particles to understand like is dark matter made
out of a particle and what is that particle rests
on a really big assumption that we can't actually justify,

(37:58):
which is maybe dark matter feels something other than gravity,
Like we know it feels gravity. We invented the idea
to explain gravity we couldn't otherwise explain, and it's really
important to do that. But none of those explanations require
that it ever feels any other kind of force. It's
possible that dark matter is some particle out there that
only feels gravity and has no other charges. That's a

(38:19):
possibility that would be really frustrating because gravity is very
hard to use on particles, it's so weak. We might
never understand the particle nature of dark matter in that scenario.
So we hope, we pray. We assume that dark matter
has some other kind of interaction, maybe some force we
haven't figured out yet, and that would allow us to

(38:39):
interact with it on a particle level more powerfully than gravity.
And we need to make that assumption in order to
see it. Basically, So we make that assumption and we
move on. It could be totally wrong, and that might
be the reason we've never seen dark matter, but we
kind of got to do it.

Speaker 3 (38:53):
I mean, like, if you guys finally figured out gravity,
would that help or would that not solve the problem?
You wouldn't need to hope anymore.

Speaker 1 (39:00):
I love the tone there, like, if you guys finally
figured out gravity. It's like, have you finally shoveled the walk?
Did you finally take out the trash?

Speaker 3 (39:08):
That's right, have you cleaned your room? Daniel?

Speaker 1 (39:10):
It might be you know, if we understood quantum gravity,
we might figure out a way to enhance it, or
to manipulate it in such a way that it was
more powerful for particles. Like if it turns out that
there are extra dimensions to the universe and gravity appears
to be weak because most of the gravity's leaking out
into those other dimensions, then we might be able to

(39:31):
manipulate it and make it more powerful. For example, people
hope that exactly that is happening. When you smash particles
together at the Large Hadron Collider, you're overcoming that extra
dimensional reduction in the power of gravity to make miniature
black holes, which would reveal the nature of quantum gravity. So, yeah,
it's possible if we got off our butts and figured
out quantum gravity, that would help us find dark matter.

Speaker 3 (39:52):
I never know where conversations are going to go with you.
I didn't expect it to be like, well, if there's
another dimension, like whoa, whoa, Now we've got extra dimensions.
While we're trying to answer this question. But anyway, Okay, let's.

Speaker 1 (40:02):
Put that aside for now. And so we're assuming that
dark matter feels some other kind of force that matter
also feels, because that what allow us to see it,
Like those big tanks of liquid xenon underground. They're assuming
there's some kind of force that dark matter feels and
xenon feels. So when dark matter flies to xenon, they
can bump on each other because otherwise it's hopeless. So

(40:22):
if you make that assumption, you also are allowed to
assume that sometimes dark matter can bump into its anti
dark matter and annihilate and turn into something which can
then turn into normal matter. Right, So if there is
some new kind of force, it's got a particle called
it the dark photon. So now maybe sometimes dark matter

(40:43):
annihilates with anti dark matter into a dark photon, which
then turns into normal matter like an electron and an
anti electron, or a muon and an anti muon.

Speaker 3 (40:53):
Okay, so we've got dark matter which we can't see.
Now we need to find anti dark matter, which we
probably have all or not. That's direct, And then what
would a dark photon look like? It would annihilate a
real photon, right, is that how you know it existed?

Speaker 4 (41:07):
No?

Speaker 1 (41:07):
No, No, dark photons and real photons wouldn't interact. You're thinking
of an antiphoton, which also doesn't exist. So there's two
directions to think about here, antimatter and dark matter, which
are two separate concepts, right, but now we're combining them.
We're imagining what if there's anti dark matter that can
annihilate with the dark matter produce some new kind of
weird version of the photon, a dark photon, dark matter's

(41:28):
equivalent of a photon, and that dark photon can then
turn into normal matter. So if that's possible, which is
big assumption, no justification. We're only assuming it because otherwise
this whole line of research doesn't work.

Speaker 3 (41:41):
I can't believe you guys get grants funded, but you
go ahead. My parasites have to exist before I get
to study them.

Speaker 1 (41:46):
Being brutally honest about this because I don't want to
mislead people, and otherwise people will write it and be like,
but how do you know? And I want to be
straight up like, we don't know.

Speaker 3 (41:53):
I appreciate that, yeah.

Speaker 1 (41:54):
And so if that's happening, then what you can do
is say, well, where is dark matter DNSE in the universe? Okay,
centers of galaxies. We think a lot of it is
collected there. Let's look in the center of galaxies and
see if dark matter is smashing into its antimatter and
producing unexplained pairs of particles like an electron and an
anti electron, or muon an anti muon, and here's the

(42:16):
antimatter angle. It's rare to see antimatter in the universe.
So if there's an unexplained source of antimatter, it might
be due to dark matter annihilating and turning into matter
and antimatter. So we look out there in the universe
for unexplained sources of antimatter, which might be due to

(42:36):
dark matter annihilating with its own kind of antimatter and
turning into normal matter and normal antimatter.

Speaker 3 (42:42):
Okay, that's exciting. Have we failed that.

Speaker 1 (42:45):
We actually do have some really tantalizing signals of that.
People have looked out into space for all kinds of antimatter.
We look for positrons, which are rare but not super rare,
and there are some things out there in the universe
that make them. Like pulsars. We look for antiproton, which
are more rare than anti electrons. We look for anti deuterium.
We also look for anti helium or anti helium three,

(43:08):
which is even rarer in the universe. So the bigger stuff,
the bigger fat or juicier anti matter particles are rarer,
which makes them a clearer signal. So we have a
bunch of fun experiments looking for antimatter in space, basically
as a hope that if you see it, it might
be an indication of dark matter. And there's an experiment
on the space station. It's called AMS, which stands for

(43:30):
the Alpha Magnetic Spectrometer. Basically, it's a big particle detector
and a magnet in space. The mag that shows you
the particles bending, which tells you they're charge, so you
can tell whether they're matter or antimatter. And it's just
basically like this particle experiment that's stuck on the space station.
It's run by Sam Ting, who has already a Nobel Prize,
And they see a bunch of positrons anti electrons that

(43:53):
they can't explain, that nobody can explain. So they see
all these weird particles, these anti particles actually in space
that nobody can explain, and people have long wondered, like,
is this a signal of dark matter? Are we seeing
dark matter? And it's exciting, but it's also very indirect, like, yeah,
you're seeing antimatter, and antimatter is rarer in the universe

(44:14):
than matter, but it's not that rare, especially anti electrons
like pulsars do make a lot of anti electrons and
fling them out into space and are famously hard to understand,
So it's possible that the signal they're seeing is just
pulsars or something else weird out there in the universe
that makes antimatter, right, antimatter again weird, but not weird

(44:35):
enough that the only way to make it is dark matter.
So it's like, if you see it, it's kind of indirect.

Speaker 3 (44:41):
So it'd be helpful if we understood more about how
antimatter is made.

Speaker 1 (44:46):
Yes, absolutely, the biggest challenge in astronomy is that most
of the universe is doing weird, funky stuff we don't understand.
So when you see something you don't understand, you're like, well,
is this the thing I was looking for or something
totally weird and new that we didn't understand anyway, looking
for signals from the center of the galaxy, and you
might ask, well, do we understand the rest of the
center of the galaxy, what's going on in there and

(45:06):
all the other signals we might see. The answer is
definitely not. Like there's a huge amount of stuff going
on in the center of the galaxy. We don't know
what's in there, what it's doing, how it's interacting. It's
hidden by gas and dust. It's a big question mark.
So we're looking for a little weird signal on top
of a big weird thing we don't understand. It's like
listening for a whisper inside a rave in a language

(45:28):
you don't understand. We're doing the best we can.

Speaker 3 (45:30):
That's a daunting task. As someone who doesn't like areas
with lots of people, that also sounds very overwhelming. Okay,
so we've got an experiment on the space station. Are
we trying to collect data on this in any other way?

Speaker 1 (45:42):
We are, absolutely. There's a bunch of people looking for
cosmic ray anti matter. One of the really exciting experiments
is called GAPS. This is a huge balloon experiment that's
going to fly over Antarctica. They like build a particle detector,
then they attach it to a weather balloon and they
just fill it with helium and then just let it
float up and circulate according to the winds around Antarctica,

(46:04):
and it'll be up there for days, weeks, months, depending
on the experiment. And like these are really nerve racking
experiments because sometimes they crash. You know, it's weather and
its winds and their storms, and they lose it. And
so imagine you're a graduate student. You spent like four
years building this very delicate piece of equipment. Now you
just send it up into the skies and the hope

(46:26):
that it doesn't just like get obliterated. And so this
would be a really cool experiment because it's very sensitive
to antimatter. It's hoping to trap anti particles, so like
slow them down and trap them inside the experiment so
that they form an exotic atom bound between like matter
and antimatter. So imagine you have like anti deuterium or

(46:48):
anti helium three comes into your experiment, gets slowed down
and then like bonds with some silicon atoms, and you
have this weird atom that's like two kind of nuclei
bound together, one matter, one antimatter, and they're gonna admit
a bunch of weird light as they relax down and
then eventually annihilate and make a big flash, and by

(47:09):
the pattern of those annihilations they can tell exactly what
kind of antimatter it was. So this is a future
experiment they're working on. Somebody's out there right now, like
building this thing and preparing it for launch over Antarctica.
They've been saying for years it's like about to go,
and the last I heard, it's gonna fly in twenty
twenty five. So this might tell us something about antimatter,
cosmic rays, antimatter from space, which might be a clue

(47:33):
about where the dark matter is and if there's anti
dark matter annihilating with the dark matter to send us
messages about what it's doing.

Speaker 3 (47:41):
And do you know if that was part of the
justification for getting this project funded or was this more
a question about antimatter.

Speaker 1 (47:47):
Now, this is definitely one of the motivations for this
experiment directly. It's like understanding antimatter cosmic rays. Cosmic ray
is an enduring mystery anyway, like we don't understand what's
making them, and especially the very highest so gaps can
do lots of different kind of physics not just look
for dark matter signals, but I think the signal from
AMS is very tantalizing, and it inspires lots of follow

(48:09):
up experiments. And you know, when you see something you
don't understand, you try to explain it, and then you
do follow up experiments say well, if that's true, then
we should also see it over here, and let's do
a different kind of experiments that also spots it. Because,
like with dark matter, what you want is a coherent story.
You don't just want one unexplained data that you can
fudge away with some factor. You want a total story that,

(48:30):
when you poke at it from lots of different directions,
is always telling you the same story. And that's the
thing about dark matter. No matter how we study it,
we can tell its matter. It's there, it has gravity,
and so what we want is to complete that story
by understanding its interactions with normal matter and maybe with
anti dark matter. And so that's why GAPS is like
a very different kind of experiment from AMS, not just

(48:53):
like a repeat of it, to hope to get like
a different angle on the mystery, and maybe it'll see
something and confirm it, and then we'll all can be
convinced that we're seeing antiparticles from dark matter, or maybe
they'll see nothing, or maybe it'll see something else totally
weird that we didn't expect the way astronomy often does.

Speaker 3 (49:10):
So if they could afford it, and I know this
would be a much more expensive experiment, would it be
better to put that detector outside of Earth's magnetosphere because
some of those galactic cosmic rays sort of get stopped
or are you at Antarctica because they get shuttled to
the poles.

Speaker 1 (49:25):
Yeah, great question. There's sort of just different traditions and
physics ways people figure it out to make physics work,
and definitely launching stuff into space is one of them.
But wow, that's expensive and slow, and then you've got
to get in line and you can cancel it any
minute after ten years of work, and so sort of
an intermediate approach is like, hey, we just need a
big balloon. We don't have to go all the way

(49:45):
into space. We can just go like go to the
top of the atmosphere. And the winds around Antarctica actually
tend to propel things in a circle, so you can
sort of like float in circles and do these loops
around Antarctica. So there's a long tradition of these balloon
experiments around anti Arctica. Really amazing science and really brave,
you know, Like, I'm so impressed by these people who

(50:06):
risk everything for these balloon experiments and have to go
to Antarctica to launch them and recover them. I mean,
for some people they get to go to Antarctica, it's
like really exciting for them. But for me, I'm like, yikes.

Speaker 3 (50:17):
I agreed. Yes, I have a friend who's excited because
he got to go to Antarctica, But for me it
would be I have to go to the Antarctica, but I
don't love being cold. We got four inches of snow
and that is the right amount and it'll melt next
week and that's perfect exactly.

Speaker 1 (50:32):
And that's one of the things I love about science.
You know, it takes all kinds. It takes normal people
who don't want to go to Antarctica and crazy people
who do want to go to Antarctica, and we're all
grateful for them.

Speaker 3 (50:42):
Something for everyone exactly. All right, Well, so what do
you think, Daniel when the results of the GAPS experiment
come in or are we going to have an episode
just about what they found? Unless it crashes, let's do it.

Speaker 1 (50:53):
I definitely want to know the answer, and I want
to share the answer with everybody. And I'm just really
hoping that dark matter is interesting and complicated and has
some kind of interactions. You know, that would make sense
because our kind of matter does. It's not just like gravitational.
It interacts in all sorts of complicated ways, and we
have lots of different kinds of normal matter, all these
different particles. It would be really weird if dark matter,

(51:16):
which is most of the universe, was also really simple,
like just one kind of particle and one kind of
interaction gravity. It would be unusual. But then, you know,
the universe is not afraid to surprise us and confuse us.
So it could be that dark matter is kind of
sterile and boring. But I suspect that it's not. I
suspect there's lots of different dark matter particles and they're

(51:37):
all doing some weird, funky dance out there. It's certainly
possible that that's the case, and that's the universe I
hope we live in, because it would be much more
discoverable if dark matter is just gravitational. It could be
a long long time or ever before we figure it out.

Speaker 3 (51:52):
Well, let's hope we have the answer before we retire, perspire,
or expire. I'm keeping my fingers cross.

Speaker 1 (51:58):
For you, all right. Thanks he everyone, And so sometimes
you see there are connections between the mysteries of the universe.
Dark matter and antimatter might dance together to make themselves explainable.

Speaker 3 (52:09):
Here's hoping. Until next time. Daniel and Kelly's Extraordinary Universe
is produced by iHeartRadio. We would love to hear from you,
We really would.

Speaker 1 (52:25):
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Extraordinary Universe.

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