September 1, 2020 • 47 mins
It's not anti-matter, or supersymmetric matter, but yet another way our familiar particles might be reflected, and could explain a deep mystery of the Universe.
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Speaker 1 (00:08):
Hey, Daniel, I have a question. The particles have families.
Oh yeah, actually each particle has a whole set of relatives. Really,
so who is the electrons closest cousin? Well, the positron
is kind of like the electrons evil twin. Does you
have like a twurly mustache? Or whereas where is the
(00:29):
opposite color clothes? Yeah, and then it's got the muan,
which is like it's heavier cousin, it's more massive cousin,
Like it's more fit, like it's bulky or does it
just sit around and eat bananas? Nobody knows? Nobody knows.
And then the electron even has like hypothetical relatives. What
(00:50):
you mean, like long lost relatives. Yeah. Like there might
be a super symmetric version of the electron. We call
it the selectron. That sounds like a great suit for power.
I'd love to select my own relatives. I'm or Hand,
(01:20):
a cartoonists and the creator of PhD comics. I'm Daniel.
I'm a particle physicist, and there is no super symmetric
version of me. Is there an asymmetrical version of you?
I don't know, but if there was a super symmetric version,
it would be the Daniel or the Daniel Leno, the
Daniel Tron. I'm sure you would come up with an
(01:41):
awesome name for that version of Daniel. Welcome to our
podcast Daniel and Jorge Explain the Universe, a production of
I Heart Radio in which we take you on a
mental tour of everything that's amazing, that's wonderful, that inspires
your curiosity, everything that makes you wonder how does that work?
Why is it like that? Why isn't it some other way?
We take the whole universe and try to break it
(02:02):
down into time little pieces and explain them to you,
and we try to take you in a tour of
all the things that are out there, all the amazing
and incredible types of objects like black holes and neutron stars,
and all of the incredible and mysterious particles that are
out there and then might be out there. That's right,
(02:22):
because part of the journey of understanding the universe is
thinking about what's there and what might be there. What
would make more sense if the universe had it in it.
What do we need to add to our vision of
the universe to make it make more sense? What puzzle
pieces are we missing? Because that's how scientists explore, right,
I know. That's how we kind of probe the unknown.
(02:43):
We as we sit around and we think, well, well,
I guess you guys sit around on and I went
some coffee, and you try to think of what would
be what could be out there, what would make sense
in terms of the what the equations predict and what
the data suggests, and and try to think about what
we can discover out there and universe. Yeah, there's sort
of two ways to make big discoveries in physics. One
(03:04):
is like try to anticipate them, to look at the
pattern of what we know and say, what's missing? Would
this make more sense if we had another piece? Like
if you were doing a puzzle and you fill the
whole thing in, is one piece missing? You're going to
go out and look for that one piece and you
know sort of what to look for, you have expected it.
The other way to make discoveries just to like go
out there is an explore and see what you're find
(03:26):
and maybe you're run into something amazing you didn't expect.
That's also fun, But there's a lot of times that
we can't just do that. We don't have necessarily the
way to explore. We have to think about it in
advance and try to figure out in advance what is
it we should be looking for. I usually find my
puzzle pieces in between my couch cushions, or or under
the or on the table. I borrowed a bunch of
(03:48):
puzzles from some friends and I put the first one
together and it was missing a piece, and it had
an extra piece from another one of the puzzles. What
I think your friends are trying to drive you crazy
to think so, because then the next puzzle was the same.
So by the time the next puzzle, I had this
like two extra random pieces and two puzzles each missing
a piece. And it wasn't symmetric LIKEE was missing from
(04:12):
the other one. No, it was like a cycle. It
was like you have to finish all six to finish
any of them. It was torture. Um, I think they're
trying to gas light you in the puzzle version of
gas lighting, trying to puzzle light you down exactly. But
you know, I have to take issue with what you
said earlier that physicists, when we try to have ideas,
we sit around and think about stuff. Why is that
you think about It's just like sitting around these days
(04:34):
trying to do my thinking. Well, I'm active, I'm going
for a walk to think about stuff. I'm doing jumping
jack to think up new theories. I thought you were
going to complain that you actually lie down when you
think physics. Is that how you get your creative ideas?
Curl up under the desk or something. My best ideas
come when I have my feed up. For sure. Post
(04:54):
definitely leads to creativity. Yeah. So we know a lot
about the universe, and we know all a lot of
the particles that are out there that make up matter,
that might make up matter, and that um make up
other things that maybe are not as useful to the universe.
But there are also a lot of missing pieces in
the universe. There's a lot of empty places in our
(05:15):
ideas of particles and matter that could be filled by
new particles. That's right, because when we look at the particles,
we don't just want to make a list and say here,
all the particles in the universe were done. We want
to understand that. We want to fit them together into
patterns because those patterns are clues, clues that will lead
us to be able to pull back a layer of
reality and see what's underneath those particles, what are the tiny,
(05:39):
even smaller particles that make them up all the way
down to the smallest bits of the universe. So the
way to do that is to organize our knowledge and
look for holes. For example, before we discover the top cork,
we had five corks and they fit together in two
pairs plus one lonely bottom cork, And we thought, where's
the partner for the bottom cork? It must be out there,
(06:00):
and we went and looked for it and found it.
So this strategy of organizing our knowledge and looking for
holes and gaps and symmetries is a really productive way
to find new things. And so today on the program,
we'll be talking about one such set of wholly particles
that might exist and that might answer a lot of
questions about our understanding of the universe. So we'll be
(06:21):
asking the question, what is mirror matter and why is
it so hard to say? It is a little hard
to say. I feel a little punk tight just saying
mirror matter mirror Well, you know, there's an a whole
sociological question we'll dig into later about why mirror matter
(06:42):
is not so popular among theoretical physicists. But One answer
might be that it's just kind of hard to say.
Do you think that matters? It's more fun to say
dark matter antimatter than mirror matter. Don't, don't, don't use
alliteration when you when you discover something new and amaze
in physics, you know what you're saying and ours ours
are just horror to say their horror, horror. There there
(07:05):
are harder horror choice exactly? Is that why particle physics
has some problems there? Yeah? I think so? All right? So,
as usual, Daniel went out there into the wiles of
the Internet to ask if people were familiar with this
idea of mirror matter. So thanks to everybody who sent
in their speculations about what mirror matter might be. If
(07:28):
you'd like to speculate on a future topic of one
of our podcast episodes, please write to us two questions
at Daniel and Jorge dot com. We'd love to have
you participate. So think about it for a second before
you listen to these answers. If someone ask you what
is mirror matter, or ask you how to pronounce it?
For that matter, what would you say? There is what
(07:50):
people had to say something that reflected um like a
positive trium versus uh. You know, it's kind of the
opposite of each of the particles that we have. I
can only guess, and the name probably it's the matter
that imitates the matter that comes close to or get
gets in contact with. I have no idea. So there
(08:13):
are two things that come to my mind immediately. The
first one is antimater, but I think that this answer
is to straightforward, so I don't think this is the
right concept to your question. So the second thing that
comes to my mind, that's supersymmetry. I assume that mirror
matter talks about particle physics, and I don't know a
(08:34):
whole lot about it, but from what I know, I
think mirror matter wants to kind of explain why the
weak force is the only one that does not respect
the mirror reflection symmetry That sounds made up, sounds like
something i'd hear on Star Trek, but I'm gonna go
(08:55):
with it relates to supersymmetry. Those are words I've heard before,
or I wouggest that mirror matter is matter with the
opposite handedness. Mirror matter is maybe matter with particles of
opposite spin in charge. I'm immediately thinking of anti matter,
(09:15):
but I'm presuming it's something different, all right. I like
the star Trek reference. We should be writing for star Trek, Daniel.
Star Trek is just stealing from reality. You know, reality
is so weird that inspires hilarious fiction. But people seem
to have sort of the idea that it's like a matter,
but it's somehow their mirror image. So I guess it
(09:36):
is a pretty good name. Kind of like there's some
kind of idea about symmetry and handedness and spin, and
there seems to be a general understanding that there are
these symmetries that everything we know could be reflected. There
could be a whole other set of stuff, and exactly
the way that there are is anti matter. Now we're
talking a moment about what mirror matter is. It's not
(09:57):
the same thing as anti matter, but it does share
that thing in common that it's a reflection of the
particles we know. It tells us something about the symmetries
that are built into the universe and the ideas that
there's potentially more than one of these reflections, you know,
the reflection of all the matter particles into antimatter particles.
And you can also have the reflection potentially of matter
(10:17):
particles into these mirror matter particles. So it's in the
same sort of family of ideas, but it's just a
different kind of reflection. Man, I feel like we were
living in a house of mirrors or a universe of mirrors.
It's crazy and it's amazing, and it blows my mind
how many of these reflections there are. Because you know,
we talked about antimatter, and we will talk about mirror matter,
(10:37):
but then there are also these particle families, Like the
electron is not just reflected into the muon, it's reflected
into the muan and the tao. And so the whole
structure that we understand of the universe of particle physics
is really built around all these symmetries and reflections. I mean,
that's what we're trying to do, is like organize these
things into patterns, and the look at the patterns and say,
(10:57):
what does that pattern mean about the universe? Means that
maybe you shouldn't have decorated your whole universe with mirrors.
Perhaps you know who did, right? Who put up all
these mirrors? Right? This place is like a crazy fun house.
Why is it so hard to understand? No, it's it's fascinating,
you know, just like you can ask the question, you know,
why is there no antimatter left in the universe. You
(11:19):
can ask the question like, well, why do we have
antimatter at all? Right? Why is there this symmetry? What
does it mean about the universe that there seems to
be this balance in the list of particles, but not
in their actual existence, right and so so and some
people also mentioned the idea of supersymmetry, But mirror matter
is not related to supersymmetry, right, that's right. Supersymmetry is
(11:40):
yet another hypothetical reflection and that looks to try to
build a symmetry into the universe. It says, we have
some particles called fermions and make up matter particles, and
other particles called bosons that make up forces like photons
and z bosons. What if each of those has a
corresponding particle on the other side, Every fermion has some
boson that corresponds to it, So the electron has a selectron,
(12:04):
and the mulan has a smew on, And then every
boson like the photon, has a fermion partner. So the
photon would have a photino and the w particle would
have a we know, for example, and so that again
just reflects the whole set of standard model particles over
into a new set of hypothetical particles that we have
not yet discovered and are not the same as antimatter
(12:25):
and not the same as mirror matter. It's just another
kind of reflection that tells you about how we're always
looking for symmetries in the universe. But this one seems
to claim the mantle of mirror matter, Like it just
grabs that word and says, I'm the I'm the mirror
type of matter. Yeah, exactly, and it's mostly championed by
like one guy in Australia. Wait. Wait, this is a
(12:50):
major physics theory that has a support of exactly one physicists,
not exactly one physicist. But you know, um, not that
many physicist believe in mirror matter. Although other people have
ideas that are very similar to mirror matter, they just
don't call it that. So maybe it's just the naming issue.
People like, we hate that name. We're gonna come up
with a similar idea and call it something else. Yeah,
(13:13):
you're telling me that this idea also has other names,
like alice matters, or shadow matter. Yeah, that's that's all
the same one idea with several different potential names. So
I guess, you know, the community around mirror matter was
trying out a few things to see what would stick,
and I guess mirror matter is the most popular. I
kind of like alice matter because it has the like
literary reference to it. I like shadow matter. It sounds
(13:35):
like something out of Dungeons and Dragons. You're gonna roll
a die and try to use your shadow matter sword. Yeah,
the shadow mage uses a shadow matter sword. Of course.
I think it's too similar to dark matter, you know,
because then people are like, well, if you put matter
in the shadows, does it become dark matter? You know,
it's very confusing. All right, well let's jump right into
(13:56):
Daniel what let's answer the question what is mirror better.
I'm guessing it has to do it's sort of like
supersymmetric matter. But maybe you're saying it's a different kind
of mirror. Yeah, it's a different kind of mirror. So
whenever we create a new set of hypothetical particles to
balance the particles we have, it's because we see an imbalance,
we see something asymmetric, and we wonder why do we
(14:17):
have positive charge particles and not negative for example, Or
you know, why do we have fermion matter and boson
forces not the opposite. So in this case, we've created
a whole new set of particles, the mirror particles, to
try to balance the parity asymmetry of the universe, the
symmetry about being reflected in the mirror? Does the universe
look the same when you reflected in the mirror? And
(14:38):
we've talked on the podcast several times about how our
universe seems to be weirdly left handed, like some parts
of the standard model, the forces that are involved like
to only talk to particles that are left handed and
not right handed, and that's weird. I guess it all
sort of goes back to the concept of particles and
matter having um like properties or values of things charge
(15:01):
or color or what's the other one, spin spin, favor,
spin flavorite. They have all these properties and so, and
really in the math you can just flip them and
such a particle could still exist. Like mathematically you can
flip these things, even though you may not necessarily see
them in nature. Right, That's kind of the idea, is
(15:22):
that particles has these properties, and you can flip some
of them, and sometimes you see particles that have them,
and sometimes you don't see particles that have them. Yeah,
that's exactly right. We look at the structure of our
theory and we wonder if it's symmetric. We're like, well,
what happens if you flip all these things? You know,
if you flip the charges from positive negative, or you
flip everything for the minus z access to the positive
(15:44):
z axis, or you run time backwards, and all these things.
We wonder, like, is our theory symmetric? And so as
you say, you can take this this set of particles
and you can say, well, do we have the opposite
set in this sense or in this other sense, or
in this third sense? Do we have the opposite set?
You know, do exist? And if not, then why not?
Because that tells you something about the universe, right, like
why do we only have negatively charged electrons and not
(16:08):
positively charged electrons, you know, positrons? And so it's it's
interesting because you feel like there must be a reason.
We like to think that that the universe should be symmetric,
because that makes sense because if it's asymmetric, then like
who made that choice? Right, why matter or not antimatter?
Did somebody flip a coin? Is it totally random? And
we don't like that. In physics, we don't like things
(16:28):
that don't have explanations, So we like things to be
symmetric because then then they don't need explanations. So we
take our theory, we look for all the things that
are asymmetric, and then we try to fill in those holes.
But I guess when when you know, why do physics
have a preference for symmetry, like um, when you couldn't
you ask the same question like who made the universe symmetric?
Like if the universe was symmetric, wouldn't you ask the
(16:50):
same question? That's a great question, and that really goes
to philosophy. Um, And it's a question of what's simple.
You know, when we look at a physics theory, we
have questions about it. And when we compare two different
physics theories, we want the one that's simpler, that needs
like less explanation and fewer ideas. And that's sort of um.
You know, we don't know why the universe is that way,
(17:11):
but it does seem to work that way. That's simpler
ideas seem to work best, and so I would just
ask fewer questions about a theory that was symmetric than
the theory that was asymmetric, because a theory that's symmetric,
you're right, there's no reason why the universe has to
be symmetric. But it just seems to make more sense
intuitively or or aesthetically. But you know, that's not a
(17:32):
scientific feeling at all. That's sort of like a philosophical
um um or personal aesthetic feeling. Yeah, that's what I mean.
It's like if one of your kids was really well
behaved on the other one was a lot of trouble,
and you'd be like, yeah, that that makes sense in
the universal cosmic balanced sense. I think there is something there, though,
(17:53):
because if the universe is asymmetric, there are lots of
ways it could be asymmetric, but there's only really one
way to be symmetric. And so if you're asymmetric, and
you're asymmetric in one particular way, then you have to
wonder why are we living in a multiverse where every
choice for that asymmetry is made. Are there other universes
out there that are antimatter instead of matter, for example,
or are we living in a simulation where this was
(18:14):
decided by the people who ran the simulation. It's just
sort of unsatisfying to not have an explanation if there
are lots of options, whereas if there's only one option,
then you know that's just the option. You can ask like,
why is there only that option? And that's a deeper question,
like if both your kids are well behaved, you'd be suspicious.
I'd give my wife credit if that was the case. Unfortunately,
we don't live in that universe. Al right. Well, okay,
(18:39):
so mirror matter, then, is a matter that also breaks
one of these symmetries in nature that you have, and
it's sort of related to the weak force, right. I
find it a little confusing to think about parody because
it's hard to think about whether it matters if you're
reflected in the mirror, whether the universe prefers right handed
or left handed. Now it's the same basic concept, but
(19:02):
I think it's easier to think about whether it matters
if you rotate your experiment, whether the universe has a
preferred direction, which seems obviously crazy. Imagine you throw a
ball and it follows some law of physics, right, parabolo
goes up and it comes down. Now you watch that
same ball toss, but now you're standing on your head.
It looks a little different, right because you're you've rotated yourself,
(19:24):
But the same laws apply, and like you can still
apply the laws of physics to the ball. Moving shouldn't
matter if you're standing on your head, right, except that
now down means up and up means down. Yeah, exactly,
you have to put some minus signs in there, but
the same laws do apply. Now you don't see exactly
the same thing, Like it looks different if you're standing
on your head, but the same rules apply. And so
(19:45):
parody is sort of like that, like if you reflect
something into the mirror, do the same rules apply or not?
And people for a long time thought, well, of course,
like just because you're doing in the mirror, the same
rules should apply. Like it would be nonsense if our
you niverse was somehow left handed and it looked different
in the mirror, and like the mirror was right handed,
it would be weird. They would be weird. And people
(20:07):
just assumed for like, you know, as long as people
had this idea, until about fifty years ago, people assumed
the universe was symmetric in the mirror that if you
didn't experiment, it would look the same in the mirror
that you know that the mirrors that in the in
the mirror world, the same laws of physics would apply.
Now we can't actually go to the mirror world. We
can't do the mirror experiment. Right, the ideas we do
(20:28):
experiments in our universe and we think about what they
would look like in the mirror world. We try to
we imagine that all the experiments we do in our
universe would look the same in the mirror world. But
but he neverse is a little bit weirder than that.
The universe is super duper weird in fact, and it
was about fifty years ago the people realized, you know,
(20:49):
we never actually checked to see if this is true
for all the different kinds of interactions. They had checked
for the strong force, they had checked for electromagnetism, and
parody was preserved like everything a perfect sense, but nobody
had actually checked for the week interaction. And then one
summer people wrote this paper realizing, wow, nobody's ever checked
this one thing. Somebody should do it, and the paper
(21:10):
came out, and then over Christmas vacation, a scientist at Columbia,
the famous professor C. S. Wo. She did the experiment
and she set up a system that would look different
in the mirror. So they broke the mirror. And that
was seven years of seven decades of bad physics. Luck
Is that kind of what happened? Yeah, exactly. All right,
let's jump into the details here about the weak floorce
(21:32):
and symmetry and left and right handedness. But first let's
take a quick break. All right, we're talking about mirror matter.
(21:52):
And this is um not related to how I looked
like in the morning when I look in the mirror, Daniel,
that's right, but there is no face. Six could explain
that this relates to how particles look in the mirror,
because particles, as weird as they are, they have this
bizarre property that they're either left handed or right handed.
And of course particles don't have hands right, but they
(22:14):
do have a property which gets inverted in the mirror
sort of the way that left handedness and right handedness does.
And that's when you compare the direction they spin with
the direction they're moving. And because clockwise spin in the
mirror still looks clockwise, whereas moving in the mirror can
get flipped in the other direction. So a left handed
(22:35):
particle um looks like a right handed particle in the mirror,
and a right handed particle in our universe looks like
a left handed particle in the mirror. Right, It's kind
of like the mnemonic, you know, like when you use
your hand, like you point your thumb one way and
then you curl your fingers, and that that's sort of
like a handedness kind of thing for particles. Right, Like
the thumb could be pointing to where its going, and
(22:57):
the curl of your finger points to how it's spinning.
And so when you look in the mirror, that looks
not the same, that's right, And that tells you if
a particle is left handed or right handed, is it
moving in the same direction as its spin vector is pointing,
or is it moving in the opposite direction. And in
a mirror, left handed particles turned into a right handed particle. Now,
the weird thing is that the weak force, the weak
(23:19):
nuclear force, only interacts with left handed particles. It totally
ignores right handed particles. That's the big asymmetry that they're
the force ignores these other particles. It doesn't interact with
them at all, you know how some forces interact with
some particles and not others, Like the strong nuclear force
doesn't interact with electrons. Electrons just totally ignore the strong force.
(23:41):
Oh I see, it just doesn't apply to that. It
just doesn't apply. So there are actually two kinds of electrons.
There's the left hand electron and the right hand electron.
The weak force only interacts with left handed electrons. It
doesn't interact with right handed electrons at all. And that
to do right handed electrons exists? Are there? Are they
(24:02):
out there right lying around ignoring the weak force absolutely
all the time? There are left hand, right handed electrons,
and only left handed electrons interact with the weak force.
And that's what causes this parity asymmetry. In the mirror,
the weak force interacts with right handed electrons, but in
our universe it only talks to left handed particles neutrinos, electrons,
(24:23):
and quarks. That is so bizarre, it's really weird. It's
a huge asymmetry. And it's not like a little asymmetry
like it talks to left handed particles more than right
handed particles. It's complete asymmetry. Only ever talks to left
handed particles, never too right handed particles. What if I
threw and right handed electron, like, nothing would stop it
(24:44):
in terms of the strong force, in terms of the
weak force, in terms of the weak force, Yeah, that's right,
but you don't really notice that because the weak force
is super weak, and right hand electrons still feel electromagnetism
right the photons, and it's biased, but it's a weak
by that's right, um and and so most of the
interactions work with both of them. But the weak force
(25:05):
only talks to the left handed particles. And that's why,
for example, we've never seen a right handed new trino,
because neutrinos only feel the weak force, and so the
only way to talk to neutrinos is through the weak force.
But the weak force doesn't talk to right handed particles,
and so we've never seen a right handed new trino. Wow,
(25:25):
it's not just that it it has a bias against
the electron being right handed, has a bias against any
particle being right handed. That's right. There are two kinds
of every particle, that is, the left handed kind and
the right handed kind. And the weak force only talks
to left handed quarks. To what left handed electrons, left
handed muans? Left handed new trinos it never talks or
right handed anybody. It kind of makes me wonder if
(25:46):
there's a right handed weak force. Have you guys thought
about that? Like, is there are? Maybe there are two forces?
And that's the genesis of the idea for mirror matter.
This kind of it's me and the from Australia. No,
but that's exactly. This kind of asymmetry makes you wonder
is there's something out there to balance it? Right? That
(26:07):
was exactly the thought you just had live right here
on the program. And that's the whole motivation for this
entire program of physics is can we find something else
out there to balance it? You didn't like that asymmetry,
and you're like, let's fill in that gap, let's balance
the universe. And that's exactly what we're trying to do
with mirror matter. Yeah, because I believe in cosmic justice.
(26:28):
And so there's sort of two different sets of ideas there.
One is a minimal idea and say well, can we
restore the balance by saying, well, maybe there is a
right handed neutrino out there. We've just never seen it
because we can't interact with it with our weak force.
So maybe there's a right handed neutrino, and then like
some other version of the weak force that's biased in
the other way, like a w prime boson and is
(26:50):
the prime boson, And and that's a cool idea, um,
and that would restore some balance. I mean it would.
It would mean that the universe sort of cracked in half.
It's not really symmetric, it's sort of like cracked in half.
And we have two different pieces, and we happen to
be on the left handed part of it. The mirror
matter takes a step further and it says, instead of
(27:10):
just adding a right handed new trino and a new
force to talk to it, let's copy all of the particles.
So let's take the electron and make a mirror electron,
and let's take the quarks and make mirror corks. And
let's have a whole new set of forces, a mirror
strong force and mirror weak force and mirror electric force.
And in that whole mirror then parody is violated in
(27:33):
the opposite direction. So rather than just adding the minimal
pieces to our standard model to balance parody, reflect the
whole thing and this have the whole thing be balanced
in the other direction. But well, wait, I thought that
right handed electrons did exist. Right hand electrons do exist. Yeah,
And so this idea would say, well, let's make mirror
electrons and you'll have both left and right handed mirror electrons. Right,
(27:57):
and we have left handed neutrino, so this would make
right handed mirror neutrinos. Oh, I see, it's like a
whole different It's like a whole new set of two hands. Yeah, exactly.
It's like you got one family, you know, where everything
is balanced, except the neutrinos only left handed. And instead
of just inviting one more neutrino that's right handed, invite
(28:18):
a whole other family, right if they have a right
handed neutrino. It's it's more like in our family, we
only like the kids that are right hand the left handed,
and instead of making up because we have kids that
are left handed, right now, we have kids that are
right handed, we just don't like him. And to balance
it out, maybe there's another family out there down the
(28:40):
street that that has right and left handed kids, but
they have a different, different preference, different they make different
parenting mistakes that balance our parenting mistakes, and a whole
and the terrible in a whole mirror symmetric play. That's right.
The universe doesn't care if you make parenting mistakes as
long as somebody else is making the opposite one. That's
(29:01):
the physics approach to parenting. Symmetry is restored and all
is good. Oh man, I'd love to see maybe wouldn't
love to see how things work in your house and
then you um, But there's some fascinating twists. They're like.
One of them is gravity is not mirrored. If there
is a graviton, this particle that transmits gravity and a
(29:23):
quantum theory of gravity, it would not be mirror. There
would not be like a mirror graviton. It's like it
sits at the edge of the mirror or something. Yeah,
because it sits at the mirror line. Because gravity is
how we bend space, and there's only one space. We
think that our particles and the mirror particles live in
the same space. If they have their own graviton, that
have to have their own space, and that would be weird.
(29:44):
And so yeah, it sits on the mirror itself. Okay.
So the idea of mirror matter then is that there's
a whole set of matter particles that are mirrored somehow,
in this bias that the weak force has, and there's
a whole different weak force that has a different bias. Yeah,
if you build that parody violation experiment that Dr Wu's
(30:06):
experiment out of mirror matter and did the experiment, you
would get the opposite results. I guess my question is
where does this where's all? Where is all this mirror matter?
Like you sit on top of us? Is it next
to us? Is it kind of like a parallel universe
kind of thing. Well, we don't know if it exists,
first of all, and if it does exist, to be
very hard to see. And so in that respects it's
sort of similar to dark matter, because we suspect we
(30:29):
might only have gravitational interactions with it that we'll talk
in a moment about other ways we might probe it,
And so it could be right here on top of
us without us interacting with it. A right, Remember that
the universe is filled with all sorts of invisible stuff
that you cannot sense, like all the new trinos that
are flying through you right now, that you don't interact
with all the dark matter that surrounds the Earth and
(30:50):
fills your room. You can't see or touch or interact
with So it's possible to share space physically overlap with
other kinds of matter that you if you do not
direct with them. And mirror matter, if it exists, we
may only interact with it gravitationally, which is very very weak,
which means essentially we wouldn't sense it. And so if
there is mirror matter, could be right here on top
(31:10):
of us, but it could also be out there in
the universe, separated from us. Well, yeah, I guess, yeah,
I guess like dark matter and the trains, they're all
sitting on top of us, but we don't feel them.
Maybe there's a whole bunch of right handed laws and
right handed matter that's sitting on top of us too. Yeah,
there could be a right handed horgy and doing a
right handed podcast right now, doing it the right way
(31:33):
we left, and we'd feel left out exactly. Wow. Alright, So, um,
I guess my question is like, why why wouldn't our
week fource with the left handed bias interact with the
left handed mirror matter? Do you know what I mean? Like, like,
(31:55):
if in my house I only like my left handed kids,
wouldn't I like the right handed kids in the other house. Well,
first of all, I hope that either all your kids
are left handed or they don't listen to this podcast. Um,
but you're right, but our forces don't interact with those
particles at all. So those particles don't carry like electric charge,
(32:16):
they carry mirror electric charge, and they interact with like
the mirror photon, with mirror electromagnetism. And so yeah, you
might ask, like, why do you need to create all this,
all these particles, Why don't you just add a right
handed neutrino. And I think that's one of the biggest
sort of theoretical criticisms of this idea is that it's
too much. You don't need all this extra stuff. It
(32:36):
just seems like too much of a copy. But the
reason to do it, remember, is to try to restore symmetries,
to try to say, well, let's have balance in the universe.
And and then you might ask, but you know, we're
not really balanced. We have like two pieces cracked in
half that sort of compliment each other, but we're living
on one half of it, right, It's not like the
universe has this symmetry sort of broken, and we see
(32:58):
that a lot in particles ZIX that we see symmetries
that have been broken, and we think that these symmetries
are fundamental, that they like existed in the early parts
of the universe when everything was hotter, when the universe,
when different effective laws of physics were taking place, and
then as the universe cooled, just sort of like cracked
the way you know ice can crack as it freezes,
(33:19):
or where things can crack as a change phase, or
like we we everything felt to one side of the
mirror kind of or got trapped inside. Yeah, and we
ended up trapped in one side of the mirror, and
that there's other particles that got trapped on the other side.
And so these are what we call broken symmetries. We
think that they do reflect something deep that's happening in
the universe, but that they got broken, and we actually
(33:40):
see examples of those, like the Higgs boson is a
broken symmetry. Like the Higgs boson unifies the weak force
and electromagnetism, and it says that the photon is actually
part of the electroweak force. It should go along with
the W bosons and the Z boson, But when the
universe was cooling, the Higgs sort of stuck in a
(34:00):
weird spot, and it gave all this mass to the
w n Z and none to the photon. It broke
that symmetry. And so in the same way symmetry is
that existed in the early hot universe can be broken
as a sort of the phase of the universe changes,
you know, universites and go from like liquid to gas.
But as it cools, different physics sort of takes over,
and so we think that that might have broken. So
(34:22):
that's another explanation for the asymmetry. That wouldn't require this
whole new universe sitting on top of us that we
can't see her touch. That would explain why this symmetry exists.
Sort of at a higher level, it's like, you know, yeah,
we still have an asymmetry here today, but we think
that maybe there was a symmetry early in the universe,
that that the other half exists, that it explains why
(34:43):
the symmetry was broken at some point. All right, So, um,
it sounds like a pretty amazing and incredible concept. I
guess the question now is how do we verify if
it's true? How how do we know it's real? And
how do we look for these mirror particles? I guess
we can't just look in the mirror. Then, Oh my god,
nobody thought of that. I'm gonna do that right now,
(35:03):
Hold on, Nobel prize right here, mirror? What's the noble
mirror of Nobel Prize? Is the Lobel Prize? Literally? Yeah,
do you have to pay a million dollars for that one?
That's why nobody accepts it. All right, let's get into
how we look for a mirror matter, But first let's
(35:23):
take a quick break. All right, Daniel, sir, there might
be a whole mirror universe of mirror electrons and quarks
(35:45):
and particles and also forces. There might be a whole
universe of mirror forces, like the opposite electromagnetic force and
opposite strong force sitting right on top of us right now,
acting and ignoring us. But yeah, and they might even
have like better snacks than we have. Yeah, all the
(36:05):
bananas would be um curve the other way. They would
actually be tasty. But you would still hate it though,
probably would hate it. Yeah, all right, I guess that
the question is how do we look for a mirror
matter if it does exist? And how could we ever,
you know, confirm the existence is something we can't see
(36:25):
or touch? It's pretty tough. In the sort of cleanest
version of the idea, we can only interact with mirror
matter through gravity, and so in that sense, we can
only look for its effects on a gravitational scale, which
means like looking for it the way we look for
dark matter, because gravity is kind of like the the
one thing in common we have with mirror matter, Like
(36:47):
it's it's like a two vent diagrams that touch at
a point. Yeah, it's the only way that we can
interact with it, And so to discover something, to prove
that it exists, to understand it, we need to be
able to interact with it. There could be all sorts
crazy stuff happening right here on top of us, but
if it doesn't interact with us, then we could never
discover it. But we think that gravity is sort of universal.
(37:07):
Everything that has mass feels gravity. That's like another way
that gravity is super weird and amazing. But so we
might have to just use gravity to study it. And
then there's the natural question of like, well, if there's
all this weird stuff out there that we can't see
and gives us extra gravity, maybe it's not like dark matter.
Maybe it is dark matter that's what I was about
(37:28):
to ask Daniel. It feels like the perfect conspiracy theory
bom bom bomb. But this guy in Australia has cracked.
O Um. People always right in and try to connect
the mystery of dark matter with other mysteries. You know,
is dark matter like antimatter? Is dark matter? This is
dark matter that? And it's super fun. It's fascinating because
wouldn't it be awesome to like crack two mysteries simultaneously, right,
(37:52):
to solve two big questions of physics at once. This
seems really tantalizing, right because you just told me that
there might be a whole universe of matter out there
that we can't see a touch, but that influences us gravitationally.
Then that that sounds like exactly like dark matter. Yeah, Well,
do you want the good news first or the bad news?
I want? I want the news that gives me the
(38:13):
Nobel Prize. Okay, well, then here's the good news, and
you should go off on your trip to get the
new prize before you hear the bad news. In this case,
the good news is that you can use dark matter
detectors to look for this kind of stuff, and that
there is a detector out there. It's called the DAMA experiment.
It's in Italy, and it's actually had a very strong
signal for dark matter for like more than ten years.
(38:36):
We're gonna do a whole episode on why nobody believes
that DAMA detected dark matter despite their amazing evidence for
a dark matter and nobody's been believing their signal. They
have this very clear signal that looks like it should
be dark matter, but nobody else sees it, like other
dark matter experiments don't see the same thing and they should.
But this guy in Australia has this explanation. He's like, oh, well,
(38:57):
maybe that's because um, those dark other dark matter experiments
are only sensitive to heavier versions of mirror matter, and
this one experiment in Italy is different from all the
other ways in such a way that makes it sensitive
to mirror matter. So he thinks that this Dama experiment
might actually be a signal of dark matter and a
(39:18):
signal that dark matter is mirror matter. Is this one
of the ones that that you know has has like
a huge vat of some noble gas sitting around waiting
for things to ping ping it. Yeah, it's sort of
similar it's a slightly different setup, which is why it's
a little bit different, and we'll dig into the details
on another episode. But they have this signature that most
of the people in the community think probably isn't dark matter,
(39:41):
but you know, they believe it, and their experiment is
different from other experiments, and so they try to find
like a reason why only they would see this thing
that other experiments don't see, and they're saying it could
also be mirror matter, meaning that they're both the same thing. Yeah,
and so Bob Foot in Australia he wrote this paper saying,
ha ha, maybe this ex planes why Dama is seeing
this weird signal and it's a discovery of mirror matter.
(40:04):
So that was pretty exciting for a few minutes. But
but somebody found an error. Well, it's a little bit
unlikely because we know that dark matter, if it exists,
is cold, right, it's not fast moving. It tends to
poke around the universe, it doesn't zip around, whereas mirror matter,
(40:25):
if it's real and it really is a mirror of
everything we know, should have similar properties to our matter.
It should there should be relativistic elements of it. And
so already we think like, well, mirror matter doesn't really
fit the same profile of dark matter. What we know
about dark matter doesn't really mimic everything we know about
the standard model. It seems like it should be heavier
(40:45):
and slower. Mirror matter is too hot for dark matter.
That's right, exactly. Everybody looks better in the mirror, right,
everyone looks hotter. Yeah. Well, but I guess, um, I mean,
are you saying that dark matter is significantly colder in
general than we are? Yes, m absolutely, you know, I see. Yeah.
(41:06):
And then the other thing is that that was fifteen
years ago, and since then there has been a lot
more experiments looking for dark matter and cross checking the
DAMA experiment, And if mirror matter was making a signal
in the DAMA experiment, we would have seen it in
some of these other experiments c d M S and xenon.
And it's not as special anymore. Yeah. So there was
a brief window, you know, when the experiments looked like
(41:29):
they might support this crazy idea, and that was exciting
for a few minutes, but it sort of fell apart,
all right. So, um, not a lot of support experimentally
for this idea. Are there any other ways that we
could find mirror matter. Well, the other things we could
do gravitationally are trying to look for its effects, you know, astronomically,
because it might be that mirror matter isn't like diffused
(41:52):
and spread out the way dark matter is. It really
does have interactions that can form interesting structures, like there
could be mirror stars out there, or there could be
mirror galaxies and mirror planets, right, and so that could
be exciting. Would we be able to see them Do
they still spit out you know, photons or do they
spit out mirror photo They spit out mirror photons only
for the mirror astronomers to write mirror papers about and
(42:14):
win mirror Nobel prizes. Um. But of course we might
be able to see their effects gravitationally. But you know,
these are not studies where you're like looking for individual
particles of mirror matter, but you're like looking forward distortions
in cosmic gravitational fields. You know, we talked on the
podcast before about weird gravitational anomalies in the universe, like
(42:34):
the Great Attractor, a strange source of localized gravity somewhere
beyond the Milky Way that we can't explain in terms
of the stuff that we see. So that's the kind
of thing that you might try to explain using like
mirror galaxies. Oh but I guess at the mirror at
the galaxy level, it's sort of maybe indistinguishable from dark matter, maybe,
(42:57):
except that dark matter tends to clump with normal matter.
Dark matter normal matter tend to overlay each other. In fact,
the reason you have normal matter where it is is
because there's dark matter. They're like pulling it together. So
then are you saying that there could be a mirror planet,
like right now in our Solar system spinner around our sun.
(43:18):
We just can't see it, but we might feel it gravitationally.
Is that kind of the idea. That's kind of the idea.
I mean, I never thought about in terms of like
a whole mirror planet in our solar system. That's pretty awesome,
And I'm right now writing that down for an idea
for a science fiction novel, which somebody should write. That's
pretty cool. I was more thinking about like entire mirror
galaxies separated from ours. But no, you're right. I mean,
(43:38):
if our matter feels gravity, it could pull on this stuff,
and so our son could have a mirror planet surrounding it,
And in fact, Bob Foote from Melbourne claims that some
weird things in the Solar system support the existence of
mirror matter. H like that there could be mirror asteroids
kind of in in the in how all of the
(43:59):
things in our solar system move around. Yeah, and he's
looked at some like craters on some things in the
Solar system and claimed that they can't be explained using
normal impacts from normal asteroids. You would need a mirror
asteroid to explain it. And I'm pretty spectical and glass everywhere,
and you're like, like, it has to be a mirror collision.
(44:19):
I'm pretty skeptical of that because you know, mirror objects
wouldn't collide with normal objects the normal way, right, They
don't feel electromagnetism or the strong force, so they would
mostly just pass through each other and affect each other
just gravitationally, So you can't really have like impact sites
or collisions in that same way. You can only feel
a gravitational tug. So that would be pretty spectacular. But
(44:41):
I'm not sure I buy that argument all right, But
it sounds like a pretty interesting idea, and again, I
think it really taps into against the whole feeling that
maybe there's a whole universe out there that's kind of
on top of us but maybe unreachable. You know, all
these ideas are fascinating for that reason, and this idea
may be wrong or maybe right, but it's definitely true
(45:02):
that there is stuff out there that we don't understand,
that there's a whole invisible universe of stuff going on
that if we could tap into it and figure it out,
would give us a sense of context, you know, like
where which part of the puzzle are we in. It's
like when you're doing a puzzle and you're just working
on a time a little bit and you don't even
really know, like where does this go? Is this part
of that foot, there's this part of the person's face.
That's where we are in physics. We have no idea
(45:23):
where our little piece fits in. We know that the
puzzle is huge and we've only tapped into a little
bit of it, and so this is temptation will be like, well,
maybe this fits on over here, maybe this is other
part over there. And so it's definitely a good idea
to look for weirdnesses and what we see and try
to reflect it into the larger context. I think that's
definitely a good way forward. I'm not sure about this
(45:44):
particular theory, but you know, I'm definitely a fan of
this kind of idea. I like what you did there, Daniel,
he said, reflected. I reflected on that joke for a while.
All Right, well, m hopefully that will get everyone to
think a little bit about all of these amazing symmetries
we have and and all of the amazing asymmetries that
(46:05):
we have in our universe, because you know, there has
to be kind of a reason for these weird, unexplained
patterns in our universe. That's right, and anybody out there
could be the person who figures it out. We joke
around a little bit about how this just one guy
in Australia, but you know, it only takes one person
to have an idea and to change the world, and
(46:25):
for that to be correct. Einstein was just one guy,
you know, Maxwell was just one guy. All these people
who contributed to science, they had an idea and they
propagated it forward. And so that could be bob Foot
in Australia, or it could be you, or it could
be your kids. So everybody out there should be thinking
deeply about the universe and trying to understand the whole
context of our lives. Yeah, so all of you thinking
(46:48):
about physics, look in the mirror and raise your right
hand or your left hand and help us figure all
this stuff out. Well, we hope you enjoyed that. Thanks
for joining us, See you next time. Thanks for listening,
(47:09):
and remember that Daniel and Jorge Explain the Universe is
a production at I Heart Radio or more podcast for
my heart Radio, visit the I Heart Radio Apple Apple Podcasts,
or wherever you listen to your favorite shows. H
Hey, Daniel, I have a question. The particles have families.
Oh yeah, actually each particle has a whole set of relatives. Really,
so who is the electrons closest cousin? Well, the positron
is kind of like the electrons evil twin. Does you
have like a twurly mustache? Or whereas where is the
(00:29):
opposite color clothes? Yeah, and then it's got the muan,
which is like it's heavier cousin, it's more massive cousin,
Like it's more fit, like it's bulky or does it
just sit around and eat bananas? Nobody knows? Nobody knows.
And then the electron even has like hypothetical relatives. What
(00:50):
you mean, like long lost relatives. Yeah. Like there might
be a super symmetric version of the electron. We call
it the selectron. That sounds like a great suit for power.
I'd love to select my own relatives. I'm or Hand,
(01:20):
a cartoonists and the creator of PhD comics. I'm Daniel.
I'm a particle physicist, and there is no super symmetric
version of me. Is there an asymmetrical version of you?
I don't know, but if there was a super symmetric version,
it would be the Daniel or the Daniel Leno, the
Daniel Tron. I'm sure you would come up with an
(01:41):
awesome name for that version of Daniel. Welcome to our
podcast Daniel and Jorge Explain the Universe, a production of
I Heart Radio in which we take you on a
mental tour of everything that's amazing, that's wonderful, that inspires
your curiosity, everything that makes you wonder how does that work?
Why is it like that? Why isn't it some other way?
We take the whole universe and try to break it
(02:02):
down into time little pieces and explain them to you,
and we try to take you in a tour of
all the things that are out there, all the amazing
and incredible types of objects like black holes and neutron stars,
and all of the incredible and mysterious particles that are
out there and then might be out there. That's right,
(02:22):
because part of the journey of understanding the universe is
thinking about what's there and what might be there. What
would make more sense if the universe had it in it.
What do we need to add to our vision of
the universe to make it make more sense? What puzzle
pieces are we missing? Because that's how scientists explore, right,
I know. That's how we kind of probe the unknown.
(02:43):
We as we sit around and we think, well, well,
I guess you guys sit around on and I went
some coffee, and you try to think of what would
be what could be out there, what would make sense
in terms of the what the equations predict and what
the data suggests, and and try to think about what
we can discover out there and universe. Yeah, there's sort
of two ways to make big discoveries in physics. One
(03:04):
is like try to anticipate them, to look at the
pattern of what we know and say, what's missing? Would
this make more sense if we had another piece? Like
if you were doing a puzzle and you fill the
whole thing in, is one piece missing? You're going to
go out and look for that one piece and you
know sort of what to look for, you have expected it.
The other way to make discoveries just to like go
out there is an explore and see what you're find
(03:26):
and maybe you're run into something amazing you didn't expect.
That's also fun, But there's a lot of times that
we can't just do that. We don't have necessarily the
way to explore. We have to think about it in
advance and try to figure out in advance what is
it we should be looking for. I usually find my
puzzle pieces in between my couch cushions, or or under
the or on the table. I borrowed a bunch of
(03:48):
puzzles from some friends and I put the first one
together and it was missing a piece, and it had
an extra piece from another one of the puzzles. What
I think your friends are trying to drive you crazy
to think so, because then the next puzzle was the same.
So by the time the next puzzle, I had this
like two extra random pieces and two puzzles each missing
a piece. And it wasn't symmetric LIKEE was missing from
(04:12):
the other one. No, it was like a cycle. It
was like you have to finish all six to finish
any of them. It was torture. Um, I think they're
trying to gas light you in the puzzle version of
gas lighting, trying to puzzle light you down exactly. But
you know, I have to take issue with what you
said earlier that physicists, when we try to have ideas,
we sit around and think about stuff. Why is that
you think about It's just like sitting around these days
(04:34):
trying to do my thinking. Well, I'm active, I'm going
for a walk to think about stuff. I'm doing jumping
jack to think up new theories. I thought you were
going to complain that you actually lie down when you
think physics. Is that how you get your creative ideas?
Curl up under the desk or something. My best ideas
come when I have my feed up. For sure. Post
(04:54):
definitely leads to creativity. Yeah. So we know a lot
about the universe, and we know all a lot of
the particles that are out there that make up matter,
that might make up matter, and that um make up
other things that maybe are not as useful to the universe.
But there are also a lot of missing pieces in
the universe. There's a lot of empty places in our
(05:15):
ideas of particles and matter that could be filled by
new particles. That's right, because when we look at the particles,
we don't just want to make a list and say here,
all the particles in the universe were done. We want
to understand that. We want to fit them together into
patterns because those patterns are clues, clues that will lead
us to be able to pull back a layer of
reality and see what's underneath those particles, what are the tiny,
(05:39):
even smaller particles that make them up all the way
down to the smallest bits of the universe. So the
way to do that is to organize our knowledge and
look for holes. For example, before we discover the top cork,
we had five corks and they fit together in two
pairs plus one lonely bottom cork, And we thought, where's
the partner for the bottom cork? It must be out there,
(06:00):
and we went and looked for it and found it.
So this strategy of organizing our knowledge and looking for
holes and gaps and symmetries is a really productive way
to find new things. And so today on the program,
we'll be talking about one such set of wholly particles
that might exist and that might answer a lot of
questions about our understanding of the universe. So we'll be
(06:21):
asking the question, what is mirror matter and why is
it so hard to say? It is a little hard
to say. I feel a little punk tight just saying
mirror matter mirror Well, you know, there's an a whole
sociological question we'll dig into later about why mirror matter
(06:42):
is not so popular among theoretical physicists. But One answer
might be that it's just kind of hard to say.
Do you think that matters? It's more fun to say
dark matter antimatter than mirror matter. Don't, don't, don't use
alliteration when you when you discover something new and amaze
in physics, you know what you're saying and ours ours
are just horror to say their horror, horror. There there
(07:05):
are harder horror choice exactly? Is that why particle physics
has some problems there? Yeah? I think so? All right? So,
as usual, Daniel went out there into the wiles of
the Internet to ask if people were familiar with this
idea of mirror matter. So thanks to everybody who sent
in their speculations about what mirror matter might be. If
(07:28):
you'd like to speculate on a future topic of one
of our podcast episodes, please write to us two questions
at Daniel and Jorge dot com. We'd love to have
you participate. So think about it for a second before
you listen to these answers. If someone ask you what
is mirror matter, or ask you how to pronounce it?
For that matter, what would you say? There is what
(07:50):
people had to say something that reflected um like a
positive trium versus uh. You know, it's kind of the
opposite of each of the particles that we have. I
can only guess, and the name probably it's the matter
that imitates the matter that comes close to or get
gets in contact with. I have no idea. So there
(08:13):
are two things that come to my mind immediately. The
first one is antimater, but I think that this answer
is to straightforward, so I don't think this is the
right concept to your question. So the second thing that
comes to my mind, that's supersymmetry. I assume that mirror
matter talks about particle physics, and I don't know a
(08:34):
whole lot about it, but from what I know, I
think mirror matter wants to kind of explain why the
weak force is the only one that does not respect
the mirror reflection symmetry That sounds made up, sounds like
something i'd hear on Star Trek, but I'm gonna go
(08:55):
with it relates to supersymmetry. Those are words I've heard before,
or I wouggest that mirror matter is matter with the
opposite handedness. Mirror matter is maybe matter with particles of
opposite spin in charge. I'm immediately thinking of anti matter,
(09:15):
but I'm presuming it's something different, all right. I like
the star Trek reference. We should be writing for star Trek, Daniel.
Star Trek is just stealing from reality. You know, reality
is so weird that inspires hilarious fiction. But people seem
to have sort of the idea that it's like a matter,
but it's somehow their mirror image. So I guess it
(09:36):
is a pretty good name. Kind of like there's some
kind of idea about symmetry and handedness and spin, and
there seems to be a general understanding that there are
these symmetries that everything we know could be reflected. There
could be a whole other set of stuff, and exactly
the way that there are is anti matter. Now we're
talking a moment about what mirror matter is. It's not
(09:57):
the same thing as anti matter, but it does share
that thing in common that it's a reflection of the
particles we know. It tells us something about the symmetries
that are built into the universe and the ideas that
there's potentially more than one of these reflections, you know,
the reflection of all the matter particles into antimatter particles.
And you can also have the reflection potentially of matter
(10:17):
particles into these mirror matter particles. So it's in the
same sort of family of ideas, but it's just a
different kind of reflection. Man, I feel like we were
living in a house of mirrors or a universe of mirrors.
It's crazy and it's amazing, and it blows my mind
how many of these reflections there are. Because you know,
we talked about antimatter, and we will talk about mirror matter,
(10:37):
but then there are also these particle families, Like the
electron is not just reflected into the muon, it's reflected
into the muan and the tao. And so the whole
structure that we understand of the universe of particle physics
is really built around all these symmetries and reflections. I mean,
that's what we're trying to do, is like organize these
things into patterns, and the look at the patterns and say,
(10:57):
what does that pattern mean about the universe? Means that
maybe you shouldn't have decorated your whole universe with mirrors.
Perhaps you know who did, right? Who put up all
these mirrors? Right? This place is like a crazy fun house.
Why is it so hard to understand? No, it's it's fascinating,
you know, just like you can ask the question, you know,
why is there no antimatter left in the universe. You
(11:19):
can ask the question like, well, why do we have
antimatter at all? Right? Why is there this symmetry? What
does it mean about the universe that there seems to
be this balance in the list of particles, but not
in their actual existence, right and so so and some
people also mentioned the idea of supersymmetry, But mirror matter
is not related to supersymmetry, right, that's right. Supersymmetry is
(11:40):
yet another hypothetical reflection and that looks to try to
build a symmetry into the universe. It says, we have
some particles called fermions and make up matter particles, and
other particles called bosons that make up forces like photons
and z bosons. What if each of those has a
corresponding particle on the other side, Every fermion has some
boson that corresponds to it, So the electron has a selectron,
(12:04):
and the mulan has a smew on, And then every
boson like the photon, has a fermion partner. So the
photon would have a photino and the w particle would
have a we know, for example, and so that again
just reflects the whole set of standard model particles over
into a new set of hypothetical particles that we have
not yet discovered and are not the same as antimatter
(12:25):
and not the same as mirror matter. It's just another
kind of reflection that tells you about how we're always
looking for symmetries in the universe. But this one seems
to claim the mantle of mirror matter, Like it just
grabs that word and says, I'm the I'm the mirror
type of matter. Yeah, exactly, and it's mostly championed by
like one guy in Australia. Wait. Wait, this is a
(12:50):
major physics theory that has a support of exactly one physicists,
not exactly one physicist. But you know, um, not that
many physicist believe in mirror matter. Although other people have
ideas that are very similar to mirror matter, they just
don't call it that. So maybe it's just the naming issue.
People like, we hate that name. We're gonna come up
with a similar idea and call it something else. Yeah,
(13:13):
you're telling me that this idea also has other names,
like alice matters, or shadow matter. Yeah, that's that's all
the same one idea with several different potential names. So
I guess, you know, the community around mirror matter was
trying out a few things to see what would stick,
and I guess mirror matter is the most popular. I
kind of like alice matter because it has the like
literary reference to it. I like shadow matter. It sounds
(13:35):
like something out of Dungeons and Dragons. You're gonna roll
a die and try to use your shadow matter sword. Yeah,
the shadow mage uses a shadow matter sword. Of course.
I think it's too similar to dark matter, you know,
because then people are like, well, if you put matter
in the shadows, does it become dark matter? You know,
it's very confusing. All right, well let's jump right into
(13:56):
Daniel what let's answer the question what is mirror better.
I'm guessing it has to do it's sort of like
supersymmetric matter. But maybe you're saying it's a different kind
of mirror. Yeah, it's a different kind of mirror. So
whenever we create a new set of hypothetical particles to
balance the particles we have, it's because we see an imbalance,
we see something asymmetric, and we wonder why do we
(14:17):
have positive charge particles and not negative for example, Or
you know, why do we have fermion matter and boson
forces not the opposite. So in this case, we've created
a whole new set of particles, the mirror particles, to
try to balance the parity asymmetry of the universe, the
symmetry about being reflected in the mirror? Does the universe
look the same when you reflected in the mirror? And
(14:38):
we've talked on the podcast several times about how our
universe seems to be weirdly left handed, like some parts
of the standard model, the forces that are involved like
to only talk to particles that are left handed and
not right handed, and that's weird. I guess it all
sort of goes back to the concept of particles and
matter having um like properties or values of things charge
(15:01):
or color or what's the other one, spin spin, favor,
spin flavorite. They have all these properties and so, and
really in the math you can just flip them and
such a particle could still exist. Like mathematically you can
flip these things, even though you may not necessarily see
them in nature. Right, That's kind of the idea, is
(15:22):
that particles has these properties, and you can flip some
of them, and sometimes you see particles that have them,
and sometimes you don't see particles that have them. Yeah,
that's exactly right. We look at the structure of our
theory and we wonder if it's symmetric. We're like, well,
what happens if you flip all these things? You know,
if you flip the charges from positive negative, or you
flip everything for the minus z access to the positive
(15:44):
z axis, or you run time backwards, and all these things.
We wonder, like, is our theory symmetric? And so as
you say, you can take this this set of particles
and you can say, well, do we have the opposite
set in this sense or in this other sense, or
in this third sense? Do we have the opposite set?
You know, do exist? And if not, then why not?
Because that tells you something about the universe, right, like
why do we only have negatively charged electrons and not
(16:08):
positively charged electrons, you know, positrons? And so it's it's
interesting because you feel like there must be a reason.
We like to think that that the universe should be symmetric,
because that makes sense because if it's asymmetric, then like
who made that choice? Right, why matter or not antimatter?
Did somebody flip a coin? Is it totally random? And
we don't like that. In physics, we don't like things
(16:28):
that don't have explanations, So we like things to be
symmetric because then then they don't need explanations. So we
take our theory, we look for all the things that
are asymmetric, and then we try to fill in those holes.
But I guess when when you know, why do physics
have a preference for symmetry, like um, when you couldn't
you ask the same question like who made the universe symmetric?
Like if the universe was symmetric, wouldn't you ask the
(16:50):
same question? That's a great question, and that really goes
to philosophy. Um, And it's a question of what's simple.
You know, when we look at a physics theory, we
have questions about it. And when we compare two different
physics theories, we want the one that's simpler, that needs
like less explanation and fewer ideas. And that's sort of um.
You know, we don't know why the universe is that way,
(17:11):
but it does seem to work that way. That's simpler
ideas seem to work best, and so I would just
ask fewer questions about a theory that was symmetric than
the theory that was asymmetric, because a theory that's symmetric,
you're right, there's no reason why the universe has to
be symmetric. But it just seems to make more sense
intuitively or or aesthetically. But you know, that's not a
(17:32):
scientific feeling at all. That's sort of like a philosophical
um um or personal aesthetic feeling. Yeah, that's what I mean.
It's like if one of your kids was really well
behaved on the other one was a lot of trouble,
and you'd be like, yeah, that that makes sense in
the universal cosmic balanced sense. I think there is something there, though,
(17:53):
because if the universe is asymmetric, there are lots of
ways it could be asymmetric, but there's only really one
way to be symmetric. And so if you're asymmetric, and
you're asymmetric in one particular way, then you have to
wonder why are we living in a multiverse where every
choice for that asymmetry is made. Are there other universes
out there that are antimatter instead of matter, for example,
or are we living in a simulation where this was
(18:14):
decided by the people who ran the simulation. It's just
sort of unsatisfying to not have an explanation if there
are lots of options, whereas if there's only one option,
then you know that's just the option. You can ask like,
why is there only that option? And that's a deeper question,
like if both your kids are well behaved, you'd be suspicious.
I'd give my wife credit if that was the case. Unfortunately,
we don't live in that universe. Al right. Well, okay,
(18:39):
so mirror matter, then, is a matter that also breaks
one of these symmetries in nature that you have, and
it's sort of related to the weak force, right. I
find it a little confusing to think about parody because
it's hard to think about whether it matters if you're
reflected in the mirror, whether the universe prefers right handed
or left handed. Now it's the same basic concept, but
(19:02):
I think it's easier to think about whether it matters
if you rotate your experiment, whether the universe has a
preferred direction, which seems obviously crazy. Imagine you throw a
ball and it follows some law of physics, right, parabolo
goes up and it comes down. Now you watch that
same ball toss, but now you're standing on your head.
It looks a little different, right because you're you've rotated yourself,
(19:24):
But the same laws apply, and like you can still
apply the laws of physics to the ball. Moving shouldn't
matter if you're standing on your head, right, except that
now down means up and up means down. Yeah, exactly,
you have to put some minus signs in there, but
the same laws do apply. Now you don't see exactly
the same thing, Like it looks different if you're standing
on your head, but the same rules apply. And so
(19:45):
parody is sort of like that, like if you reflect
something into the mirror, do the same rules apply or not?
And people for a long time thought, well, of course,
like just because you're doing in the mirror, the same
rules should apply. Like it would be nonsense if our
you niverse was somehow left handed and it looked different
in the mirror, and like the mirror was right handed,
it would be weird. They would be weird. And people
(20:07):
just assumed for like, you know, as long as people
had this idea, until about fifty years ago, people assumed
the universe was symmetric in the mirror that if you
didn't experiment, it would look the same in the mirror
that you know that the mirrors that in the in
the mirror world, the same laws of physics would apply.
Now we can't actually go to the mirror world. We
can't do the mirror experiment. Right, the ideas we do
(20:28):
experiments in our universe and we think about what they
would look like in the mirror world. We try to
we imagine that all the experiments we do in our
universe would look the same in the mirror world. But
but he neverse is a little bit weirder than that.
The universe is super duper weird in fact, and it
was about fifty years ago the people realized, you know,
(20:49):
we never actually checked to see if this is true
for all the different kinds of interactions. They had checked
for the strong force, they had checked for electromagnetism, and
parody was preserved like everything a perfect sense, but nobody
had actually checked for the week interaction. And then one
summer people wrote this paper realizing, wow, nobody's ever checked
this one thing. Somebody should do it, and the paper
(21:10):
came out, and then over Christmas vacation, a scientist at Columbia,
the famous professor C. S. Wo. She did the experiment
and she set up a system that would look different
in the mirror. So they broke the mirror. And that
was seven years of seven decades of bad physics. Luck
Is that kind of what happened? Yeah, exactly. All right,
let's jump into the details here about the weak floorce
(21:32):
and symmetry and left and right handedness. But first let's
take a quick break. All right, we're talking about mirror matter.
(21:52):
And this is um not related to how I looked
like in the morning when I look in the mirror, Daniel,
that's right, but there is no face. Six could explain
that this relates to how particles look in the mirror,
because particles, as weird as they are, they have this
bizarre property that they're either left handed or right handed.
And of course particles don't have hands right, but they
(22:14):
do have a property which gets inverted in the mirror
sort of the way that left handedness and right handedness does.
And that's when you compare the direction they spin with
the direction they're moving. And because clockwise spin in the
mirror still looks clockwise, whereas moving in the mirror can
get flipped in the other direction. So a left handed
(22:35):
particle um looks like a right handed particle in the mirror,
and a right handed particle in our universe looks like
a left handed particle in the mirror. Right, It's kind
of like the mnemonic, you know, like when you use
your hand, like you point your thumb one way and
then you curl your fingers, and that that's sort of
like a handedness kind of thing for particles. Right, Like
the thumb could be pointing to where its going, and
(22:57):
the curl of your finger points to how it's spinning.
And so when you look in the mirror, that looks
not the same, that's right, And that tells you if
a particle is left handed or right handed, is it
moving in the same direction as its spin vector is pointing,
or is it moving in the opposite direction. And in
a mirror, left handed particles turned into a right handed particle. Now,
the weird thing is that the weak force, the weak
(23:19):
nuclear force, only interacts with left handed particles. It totally
ignores right handed particles. That's the big asymmetry that they're
the force ignores these other particles. It doesn't interact with
them at all, you know how some forces interact with
some particles and not others, Like the strong nuclear force
doesn't interact with electrons. Electrons just totally ignore the strong force.
(23:41):
Oh I see, it just doesn't apply to that. It
just doesn't apply. So there are actually two kinds of electrons.
There's the left hand electron and the right hand electron.
The weak force only interacts with left handed electrons. It
doesn't interact with right handed electrons at all. And that
to do right handed electrons exists? Are there? Are they
(24:02):
out there right lying around ignoring the weak force absolutely
all the time? There are left hand, right handed electrons,
and only left handed electrons interact with the weak force.
And that's what causes this parity asymmetry. In the mirror,
the weak force interacts with right handed electrons, but in
our universe it only talks to left handed particles neutrinos, electrons,
(24:23):
and quarks. That is so bizarre, it's really weird. It's
a huge asymmetry. And it's not like a little asymmetry
like it talks to left handed particles more than right
handed particles. It's complete asymmetry. Only ever talks to left
handed particles, never too right handed particles. What if I
threw and right handed electron, like, nothing would stop it
(24:44):
in terms of the strong force, in terms of the
weak force, in terms of the weak force, Yeah, that's right,
but you don't really notice that because the weak force
is super weak, and right hand electrons still feel electromagnetism
right the photons, and it's biased, but it's a weak
by that's right, um and and so most of the
interactions work with both of them. But the weak force
(25:05):
only talks to the left handed particles. And that's why,
for example, we've never seen a right handed new trino,
because neutrinos only feel the weak force, and so the
only way to talk to neutrinos is through the weak force.
But the weak force doesn't talk to right handed particles,
and so we've never seen a right handed new trino. Wow,
(25:25):
it's not just that it it has a bias against
the electron being right handed, has a bias against any
particle being right handed. That's right. There are two kinds
of every particle, that is, the left handed kind and
the right handed kind. And the weak force only talks
to left handed quarks. To what left handed electrons, left
handed muans? Left handed new trinos it never talks or
right handed anybody. It kind of makes me wonder if
(25:46):
there's a right handed weak force. Have you guys thought
about that? Like, is there are? Maybe there are two forces?
And that's the genesis of the idea for mirror matter.
This kind of it's me and the from Australia. No,
but that's exactly. This kind of asymmetry makes you wonder
is there's something out there to balance it? Right? That
(26:07):
was exactly the thought you just had live right here
on the program. And that's the whole motivation for this
entire program of physics is can we find something else
out there to balance it? You didn't like that asymmetry,
and you're like, let's fill in that gap, let's balance
the universe. And that's exactly what we're trying to do
with mirror matter. Yeah, because I believe in cosmic justice.
(26:28):
And so there's sort of two different sets of ideas there.
One is a minimal idea and say well, can we
restore the balance by saying, well, maybe there is a
right handed neutrino out there. We've just never seen it
because we can't interact with it with our weak force.
So maybe there's a right handed neutrino, and then like
some other version of the weak force that's biased in
the other way, like a w prime boson and is
(26:50):
the prime boson, And and that's a cool idea, um,
and that would restore some balance. I mean it would.
It would mean that the universe sort of cracked in half.
It's not really symmetric, it's sort of like cracked in half.
And we have two different pieces, and we happen to
be on the left handed part of it. The mirror
matter takes a step further and it says, instead of
(27:10):
just adding a right handed new trino and a new
force to talk to it, let's copy all of the particles.
So let's take the electron and make a mirror electron,
and let's take the quarks and make mirror corks. And
let's have a whole new set of forces, a mirror
strong force and mirror weak force and mirror electric force.
And in that whole mirror then parody is violated in
(27:33):
the opposite direction. So rather than just adding the minimal
pieces to our standard model to balance parody, reflect the
whole thing and this have the whole thing be balanced
in the other direction. But well, wait, I thought that
right handed electrons did exist. Right hand electrons do exist. Yeah,
And so this idea would say, well, let's make mirror
electrons and you'll have both left and right handed mirror electrons. Right,
(27:57):
and we have left handed neutrino, so this would make
right handed mirror neutrinos. Oh, I see, it's like a
whole different It's like a whole new set of two hands. Yeah, exactly.
It's like you got one family, you know, where everything
is balanced, except the neutrinos only left handed. And instead
of just inviting one more neutrino that's right handed, invite
(28:18):
a whole other family, right if they have a right
handed neutrino. It's it's more like in our family, we
only like the kids that are right hand the left handed,
and instead of making up because we have kids that
are left handed, right now, we have kids that are
right handed, we just don't like him. And to balance
it out, maybe there's another family out there down the
(28:40):
street that that has right and left handed kids, but
they have a different, different preference, different they make different
parenting mistakes that balance our parenting mistakes, and a whole
and the terrible in a whole mirror symmetric play. That's right.
The universe doesn't care if you make parenting mistakes as
long as somebody else is making the opposite one. That's
(29:01):
the physics approach to parenting. Symmetry is restored and all
is good. Oh man, I'd love to see maybe wouldn't
love to see how things work in your house and
then you um, But there's some fascinating twists. They're like.
One of them is gravity is not mirrored. If there
is a graviton, this particle that transmits gravity and a
(29:23):
quantum theory of gravity, it would not be mirror. There
would not be like a mirror graviton. It's like it
sits at the edge of the mirror or something. Yeah,
because it sits at the mirror line. Because gravity is
how we bend space, and there's only one space. We
think that our particles and the mirror particles live in
the same space. If they have their own graviton, that
have to have their own space, and that would be weird.
(29:44):
And so yeah, it sits on the mirror itself. Okay.
So the idea of mirror matter then is that there's
a whole set of matter particles that are mirrored somehow,
in this bias that the weak force has, and there's
a whole different weak force that has a different bias. Yeah,
if you build that parody violation experiment that Dr Wu's
(30:06):
experiment out of mirror matter and did the experiment, you
would get the opposite results. I guess my question is
where does this where's all? Where is all this mirror matter?
Like you sit on top of us? Is it next
to us? Is it kind of like a parallel universe
kind of thing. Well, we don't know if it exists,
first of all, and if it does exist, to be
very hard to see. And so in that respects it's
sort of similar to dark matter, because we suspect we
(30:29):
might only have gravitational interactions with it that we'll talk
in a moment about other ways we might probe it,
And so it could be right here on top of
us without us interacting with it. A right, Remember that
the universe is filled with all sorts of invisible stuff
that you cannot sense, like all the new trinos that
are flying through you right now, that you don't interact
with all the dark matter that surrounds the Earth and
(30:50):
fills your room. You can't see or touch or interact
with So it's possible to share space physically overlap with
other kinds of matter that you if you do not
direct with them. And mirror matter, if it exists, we
may only interact with it gravitationally, which is very very weak,
which means essentially we wouldn't sense it. And so if
there is mirror matter, could be right here on top
(31:10):
of us, but it could also be out there in
the universe, separated from us. Well, yeah, I guess, yeah,
I guess like dark matter and the trains, they're all
sitting on top of us, but we don't feel them.
Maybe there's a whole bunch of right handed laws and
right handed matter that's sitting on top of us too. Yeah,
there could be a right handed horgy and doing a
right handed podcast right now, doing it the right way
(31:33):
we left, and we'd feel left out exactly. Wow. Alright, So, um,
I guess my question is like, why why wouldn't our
week fource with the left handed bias interact with the
left handed mirror matter? Do you know what I mean? Like, like,
(31:55):
if in my house I only like my left handed kids,
wouldn't I like the right handed kids in the other house. Well,
first of all, I hope that either all your kids
are left handed or they don't listen to this podcast. Um,
but you're right, but our forces don't interact with those
particles at all. So those particles don't carry like electric charge,
(32:16):
they carry mirror electric charge, and they interact with like
the mirror photon, with mirror electromagnetism. And so yeah, you
might ask, like, why do you need to create all this,
all these particles, Why don't you just add a right
handed neutrino. And I think that's one of the biggest
sort of theoretical criticisms of this idea is that it's
too much. You don't need all this extra stuff. It
(32:36):
just seems like too much of a copy. But the
reason to do it, remember, is to try to restore symmetries,
to try to say, well, let's have balance in the universe.
And and then you might ask, but you know, we're
not really balanced. We have like two pieces cracked in
half that sort of compliment each other, but we're living
on one half of it, right, It's not like the
universe has this symmetry sort of broken, and we see
(32:58):
that a lot in particles ZIX that we see symmetries
that have been broken, and we think that these symmetries
are fundamental, that they like existed in the early parts
of the universe when everything was hotter, when the universe,
when different effective laws of physics were taking place, and
then as the universe cooled, just sort of like cracked
the way you know ice can crack as it freezes,
(33:19):
or where things can crack as a change phase, or
like we we everything felt to one side of the
mirror kind of or got trapped inside. Yeah, and we
ended up trapped in one side of the mirror, and
that there's other particles that got trapped on the other side.
And so these are what we call broken symmetries. We
think that they do reflect something deep that's happening in
the universe, but that they got broken, and we actually
(33:40):
see examples of those, like the Higgs boson is a
broken symmetry. Like the Higgs boson unifies the weak force
and electromagnetism, and it says that the photon is actually
part of the electroweak force. It should go along with
the W bosons and the Z boson, But when the
universe was cooling, the Higgs sort of stuck in a
(34:00):
weird spot, and it gave all this mass to the
w n Z and none to the photon. It broke
that symmetry. And so in the same way symmetry is
that existed in the early hot universe can be broken
as a sort of the phase of the universe changes,
you know, universites and go from like liquid to gas.
But as it cools, different physics sort of takes over,
and so we think that that might have broken. So
(34:22):
that's another explanation for the asymmetry. That wouldn't require this
whole new universe sitting on top of us that we
can't see her touch. That would explain why this symmetry exists.
Sort of at a higher level, it's like, you know, yeah,
we still have an asymmetry here today, but we think
that maybe there was a symmetry early in the universe,
that that the other half exists, that it explains why
(34:43):
the symmetry was broken at some point. All right, So, um,
it sounds like a pretty amazing and incredible concept. I
guess the question now is how do we verify if
it's true? How how do we know it's real? And
how do we look for these mirror particles? I guess
we can't just look in the mirror. Then, Oh my god,
nobody thought of that. I'm gonna do that right now,
(35:03):
Hold on, Nobel prize right here, mirror? What's the noble
mirror of Nobel Prize? Is the Lobel Prize? Literally? Yeah,
do you have to pay a million dollars for that one?
That's why nobody accepts it. All right, let's get into
how we look for a mirror matter, But first let's
(35:23):
take a quick break. All right, Daniel, sir, there might
be a whole mirror universe of mirror electrons and quarks
(35:45):
and particles and also forces. There might be a whole
universe of mirror forces, like the opposite electromagnetic force and
opposite strong force sitting right on top of us right now,
acting and ignoring us. But yeah, and they might even
have like better snacks than we have. Yeah, all the
(36:05):
bananas would be um curve the other way. They would
actually be tasty. But you would still hate it though,
probably would hate it. Yeah, all right, I guess that
the question is how do we look for a mirror
matter if it does exist? And how could we ever,
you know, confirm the existence is something we can't see
(36:25):
or touch? It's pretty tough. In the sort of cleanest
version of the idea, we can only interact with mirror
matter through gravity, and so in that sense, we can
only look for its effects on a gravitational scale, which
means like looking for it the way we look for
dark matter, because gravity is kind of like the the
one thing in common we have with mirror matter, Like
(36:47):
it's it's like a two vent diagrams that touch at
a point. Yeah, it's the only way that we can
interact with it, And so to discover something, to prove
that it exists, to understand it, we need to be
able to interact with it. There could be all sorts
crazy stuff happening right here on top of us, but
if it doesn't interact with us, then we could never
discover it. But we think that gravity is sort of universal.
(37:07):
Everything that has mass feels gravity. That's like another way
that gravity is super weird and amazing. But so we
might have to just use gravity to study it. And
then there's the natural question of like, well, if there's
all this weird stuff out there that we can't see
and gives us extra gravity, maybe it's not like dark matter.
Maybe it is dark matter that's what I was about
(37:28):
to ask Daniel. It feels like the perfect conspiracy theory
bom bom bomb. But this guy in Australia has cracked.
O Um. People always right in and try to connect
the mystery of dark matter with other mysteries. You know,
is dark matter like antimatter? Is dark matter? This is
dark matter that? And it's super fun. It's fascinating because
wouldn't it be awesome to like crack two mysteries simultaneously, right,
(37:52):
to solve two big questions of physics at once. This
seems really tantalizing, right because you just told me that
there might be a whole universe of matter out there
that we can't see a touch, but that influences us gravitationally.
Then that that sounds like exactly like dark matter. Yeah, Well,
do you want the good news first or the bad news?
I want? I want the news that gives me the
(38:13):
Nobel Prize. Okay, well, then here's the good news, and
you should go off on your trip to get the
new prize before you hear the bad news. In this case,
the good news is that you can use dark matter
detectors to look for this kind of stuff, and that
there is a detector out there. It's called the DAMA experiment.
It's in Italy, and it's actually had a very strong
signal for dark matter for like more than ten years.
(38:36):
We're gonna do a whole episode on why nobody believes
that DAMA detected dark matter despite their amazing evidence for
a dark matter and nobody's been believing their signal. They
have this very clear signal that looks like it should
be dark matter, but nobody else sees it, like other
dark matter experiments don't see the same thing and they should.
But this guy in Australia has this explanation. He's like, oh, well,
(38:57):
maybe that's because um, those dark other dark matter experiments
are only sensitive to heavier versions of mirror matter, and
this one experiment in Italy is different from all the
other ways in such a way that makes it sensitive
to mirror matter. So he thinks that this Dama experiment
might actually be a signal of dark matter and a
(39:18):
signal that dark matter is mirror matter. Is this one
of the ones that that you know has has like
a huge vat of some noble gas sitting around waiting
for things to ping ping it. Yeah, it's sort of
similar it's a slightly different setup, which is why it's
a little bit different, and we'll dig into the details
on another episode. But they have this signature that most
of the people in the community think probably isn't dark matter,
(39:41):
but you know, they believe it, and their experiment is
different from other experiments, and so they try to find
like a reason why only they would see this thing
that other experiments don't see, and they're saying it could
also be mirror matter, meaning that they're both the same thing. Yeah,
and so Bob Foot in Australia he wrote this paper saying,
ha ha, maybe this ex planes why Dama is seeing
this weird signal and it's a discovery of mirror matter.
(40:04):
So that was pretty exciting for a few minutes. But
but somebody found an error. Well, it's a little bit
unlikely because we know that dark matter, if it exists,
is cold, right, it's not fast moving. It tends to
poke around the universe, it doesn't zip around, whereas mirror matter,
(40:25):
if it's real and it really is a mirror of
everything we know, should have similar properties to our matter.
It should there should be relativistic elements of it. And
so already we think like, well, mirror matter doesn't really
fit the same profile of dark matter. What we know
about dark matter doesn't really mimic everything we know about
the standard model. It seems like it should be heavier
(40:45):
and slower. Mirror matter is too hot for dark matter.
That's right, exactly. Everybody looks better in the mirror, right,
everyone looks hotter. Yeah. Well, but I guess, um, I mean,
are you saying that dark matter is significantly colder in
general than we are? Yes, m absolutely, you know, I see. Yeah.
(41:06):
And then the other thing is that that was fifteen
years ago, and since then there has been a lot
more experiments looking for dark matter and cross checking the
DAMA experiment, And if mirror matter was making a signal
in the DAMA experiment, we would have seen it in
some of these other experiments c d M S and xenon.
And it's not as special anymore. Yeah. So there was
a brief window, you know, when the experiments looked like
(41:29):
they might support this crazy idea, and that was exciting
for a few minutes, but it sort of fell apart,
all right. So, um, not a lot of support experimentally
for this idea. Are there any other ways that we
could find mirror matter. Well, the other things we could
do gravitationally are trying to look for its effects, you know, astronomically,
because it might be that mirror matter isn't like diffused
(41:52):
and spread out the way dark matter is. It really
does have interactions that can form interesting structures, like there
could be mirror stars out there, or there could be
mirror galaxies and mirror planets, right, and so that could
be exciting. Would we be able to see them Do
they still spit out you know, photons or do they
spit out mirror photo They spit out mirror photons only
for the mirror astronomers to write mirror papers about and
(42:14):
win mirror Nobel prizes. Um. But of course we might
be able to see their effects gravitationally. But you know,
these are not studies where you're like looking for individual
particles of mirror matter, but you're like looking forward distortions
in cosmic gravitational fields. You know, we talked on the
podcast before about weird gravitational anomalies in the universe, like
(42:34):
the Great Attractor, a strange source of localized gravity somewhere
beyond the Milky Way that we can't explain in terms
of the stuff that we see. So that's the kind
of thing that you might try to explain using like
mirror galaxies. Oh but I guess at the mirror at
the galaxy level, it's sort of maybe indistinguishable from dark matter, maybe,
(42:57):
except that dark matter tends to clump with normal matter.
Dark matter normal matter tend to overlay each other. In fact,
the reason you have normal matter where it is is
because there's dark matter. They're like pulling it together. So
then are you saying that there could be a mirror planet,
like right now in our Solar system spinner around our sun.
(43:18):
We just can't see it, but we might feel it gravitationally.
Is that kind of the idea. That's kind of the idea.
I mean, I never thought about in terms of like
a whole mirror planet in our solar system. That's pretty awesome,
And I'm right now writing that down for an idea
for a science fiction novel, which somebody should write. That's
pretty cool. I was more thinking about like entire mirror
galaxies separated from ours. But no, you're right. I mean,
(43:38):
if our matter feels gravity, it could pull on this stuff,
and so our son could have a mirror planet surrounding it,
And in fact, Bob Foote from Melbourne claims that some
weird things in the Solar system support the existence of
mirror matter. H like that there could be mirror asteroids
kind of in in the in how all of the
(43:59):
things in our solar system move around. Yeah, and he's
looked at some like craters on some things in the
Solar system and claimed that they can't be explained using
normal impacts from normal asteroids. You would need a mirror
asteroid to explain it. And I'm pretty spectical and glass everywhere,
and you're like, like, it has to be a mirror collision.
(44:19):
I'm pretty skeptical of that because you know, mirror objects
wouldn't collide with normal objects the normal way, right, They
don't feel electromagnetism or the strong force, so they would
mostly just pass through each other and affect each other
just gravitationally, So you can't really have like impact sites
or collisions in that same way. You can only feel
a gravitational tug. So that would be pretty spectacular. But
(44:41):
I'm not sure I buy that argument all right, But
it sounds like a pretty interesting idea, and again, I
think it really taps into against the whole feeling that
maybe there's a whole universe out there that's kind of
on top of us but maybe unreachable. You know, all
these ideas are fascinating for that reason, and this idea
may be wrong or maybe right, but it's definitely true
(45:02):
that there is stuff out there that we don't understand,
that there's a whole invisible universe of stuff going on
that if we could tap into it and figure it out,
would give us a sense of context, you know, like
where which part of the puzzle are we in. It's
like when you're doing a puzzle and you're just working
on a time a little bit and you don't even
really know, like where does this go? Is this part
of that foot, there's this part of the person's face.
That's where we are in physics. We have no idea
(45:23):
where our little piece fits in. We know that the
puzzle is huge and we've only tapped into a little
bit of it, and so this is temptation will be like, well,
maybe this fits on over here, maybe this is other
part over there. And so it's definitely a good idea
to look for weirdnesses and what we see and try
to reflect it into the larger context. I think that's
definitely a good way forward. I'm not sure about this
(45:44):
particular theory, but you know, I'm definitely a fan of
this kind of idea. I like what you did there, Daniel,
he said, reflected. I reflected on that joke for a while.
All Right, well, m hopefully that will get everyone to
think a little bit about all of these amazing symmetries
we have and and all of the amazing asymmetries that
(46:05):
we have in our universe, because you know, there has
to be kind of a reason for these weird, unexplained
patterns in our universe. That's right, and anybody out there
could be the person who figures it out. We joke
around a little bit about how this just one guy
in Australia, but you know, it only takes one person
to have an idea and to change the world, and
(46:25):
for that to be correct. Einstein was just one guy,
you know, Maxwell was just one guy. All these people
who contributed to science, they had an idea and they
propagated it forward. And so that could be bob Foot
in Australia, or it could be you, or it could
be your kids. So everybody out there should be thinking
deeply about the universe and trying to understand the whole
context of our lives. Yeah, so all of you thinking
(46:48):
about physics, look in the mirror and raise your right
hand or your left hand and help us figure all
this stuff out. Well, we hope you enjoyed that. Thanks
for joining us, See you next time. Thanks for listening,
(47:09):
and remember that Daniel and Jorge Explain the Universe is
a production at I Heart Radio or more podcast for
my heart Radio, visit the I Heart Radio Apple Apple Podcasts,
or wherever you listen to your favorite shows. H
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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