Is there matter that is not made of particles?

Is it possible that matter could be made of something that's not particles?

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Episode Transcript

Speaker 1 (00:08):
Hey, Daniel, have we figured out yet what dark matter
is made out of? Checking? Checking, checking? Nope, not yet.
We'll have a new theory. I think it's made out
of everyone's lost socks. Oh man, it's not lost socks,
not even the really dark socks. No, they just aren't
enough socks in the universe to explain dark matter. All right,

(00:29):
it's not made out of socks. But have you found
the particle yet? It's made out of you know, no
sign so far. You just need to think outside the box. Well,
we're trying to be open minded. I mean, we're open
to any kind of particle, but what if it's not
even made out of particles? Then maybe asking a particle
physicist is the wrong approach. Hi am orhandmade cartoonists and

(01:06):
the creator of PhD comments. Hi, I'm Daniel. I'm a
particle physicist and I'm particularly good about thinking about particles.
And welcome to our podcast, Daniel and Jorge Explain the Universe,
a production of I Heart Radio in which we think
about everything in the universe and its particles. We try
to take all the big questions about life, the universe,
and everything and break them up into their smallest microscopic

(01:30):
little pieces so that we can all understand them, because
we all have a certain curiosity about what things are
made of. We see all the things around us and
we wonder, is that made out of what? And it's
fascinating how taking something apart is somehow explaining what it is. Right,
you look at something and you wonder, what is that thing? Well,

(01:50):
let me zoom in and see what it's made out of,
because that will give me some insight into what it is. Yeah.
This kind of strange that breaking something tells you what
it is. Yeah, I guess it tells you what's inside
or what the little bits it's made out of. Art
And it works for physics, not so much for society.
Like you meet a friend and you want to understand
what's their motivation. You don't like slice them up into

(02:10):
little pieces. Oh boy, that's dark. But in physics we
do that. We say, if we try to understand why
this wave works the way it does, or why this
hurricane turned left instead of right, we think that we
can explain it by breaking it into as small as
pieces and then somehow reassembling it mentally, understanding how those
small pieces work together to make the emergent phenomenon the

(02:32):
thing at the larger scale. Yeah, because there's a lot
of stuff out there in the universe, and by now
we know that a lot of it is made out
of atoms, and those atoms are made out of protons
and neutrons and electrons, and those protons and neutrons are
made out of quarks, and that's pretty much it. We
sort of know what most regular matter is made out of.
And this approach has worked pretty well. You know, a

(02:54):
hundreds or so years ago, we had all these weird
kinds of stuff, different kinds of metals and gases, and
all had different behavior, and we didn't understand why why
does this thing conduct electricity and this thing is active
and that thing is not. And now we found that
explanation precisely by peeling back a layer and digging deeper
and understanding what's going on inside. And it's all those

(03:15):
atomic orbitals and the electrons moving around, which precisely explains
that behavior and answers those questions. So, you know, we
make fun of it a little bit, but this approach
has been spectacularly successful. Yeah, And it's actually when you
step back, it's a little maybe surprising or interesting that
it is made out of little bits like matter, and
everything we know about is made out of little tiny

(03:36):
lego bits that you can't break apart. It's pretty weird
because things seem smooth like you look around you and
things seem pretty much like continuous It's weird to imagine
that when you zoom in suddenly it looks different, that
it looks like it's made out of these tiny dots.
Is incredible that you can make something smooth out of
something that's not smooth. Yeah, the universe, I guess that

(03:57):
as hard is chunky, like chunky peanut butter. It's not smooth. Yeah,
it's incredible. It tells you that what you see with
your eyes, your idea of the universe, just from interactions
at this sort of size of stuff and speed, is
not fundamental to the universe. That you need to dig
deeper and peer into the smaller, smaller distances to understand
what the real rules are. Yeah, and I feel like

(04:18):
this idea is kind of really ingrained now for those
of us who know a little bit of physics and science.
Is it's just that it seems natural now to think
that everything is made out of little tiny pieces. Yeah,
And That's why it's fun, I think, to go back
to the Greeks and hear their discussions. You know, they
had no data, no evidence, but they were open to
lots of different ideas about how the world might work.
Like maybe it's made out of four smooth elemental things fire, air, water,

(04:43):
and earth. Right, maybe it's made out of some tiny bits,
or maybe they had all sorts of crazy, bonkers ideas.
But the cool thing about those ideas is that they
were trying to be as open minded as possible. They
were like trying to span completely the space of possible
universes we could live in. Yeah, so everything we see
around us is made out of those little tiny bit

(05:03):
quirks and electrons. But it turns out that that's not
all there is in the universe. There's a big part
of the universe that we can't see. Yeah, and that
makes us worry that maybe we've been led down the
rose Garden path a little bit. Maybe our success in
describing the kind of matter that we are made out of,
me and you and hamsters and ice cream and lava

(05:25):
has led us to over generalize and to imagine that
that's the same pattern that applies to everything in the universe,
but maybe it's not so to the on the podcast
will be asking a really fundamental question. We'll be asking,
can you have matter that's not made out of particles? Whoa? Whoa?

(05:49):
You just put me out of a job. Man, What
do you mean your job is not to explain things? Well,
you know, if of the matter in the universe is
the kind of matter that's made out of part nicles
and eighty five percent of it is something else, that
maybe of the physicists should not be particle physicists. Well,
I guess what you mean is that we know that

(06:09):
the regular matter that we know about, you know, things
made out of electrons and courts and protons and neutrons,
only accounts for fifteen percent of the matter in the universe. Yeah,
it's percent of the matter of the universe and five
percent of the energy of the universe, because two thirds
of the energy in the universe is this other thing
called dark energy. Yeah, but there's a whole eighty five

(06:30):
percent of matter in the universe that is not like
the stuff we know about. That's exactly right, And we're
spending a lot of time trying to figure out what
it is made out of. Is it this particle is
at that particle, but sometimes people wonder maybe it's not
a particle at all. Yeah, and that's crazy to think
about that. Maybe there are things that are not made
out of a little bit. What does that even mean?

(06:51):
What does that even mean? And that's why you have
to go back to the Greeks and wonder, like, well,
what are the ideas that we left, you know, more
than a hundred years ago on the side of the highway,
once we decided that everything was actually made out of
atoms and smaller bits. But to sort of go back
to that original grab bag of ideas and consider other alternatives. Yeah,
like maybe you could have matter that's not made out
of particles, like things that have mass but not constituent

(07:15):
little pieces that what non particle matter would mean. Yeah, well,
we need to be open to other ideas. We don't
know what kind of things could be in the universe.
Particles is a kind of a Boner's idea, So we
just need to be like open to brand new ideas.
Maybe it's made out of totally smooth stuff that isn't
broken into little bits, or maybe it's made out of
something else where. The particles aren't as discreet. You know,

(07:36):
they're not counted by integers but by real numbers. All right,
So this is a pretty mind blowing question, and as
usual people wondering how many people out there I thought
about this question or might even have ideas about whether
it's possible. So, as usual, Daniel went out there into
the Internet and ask listeners if they thought that matter
could be made not out of particles. That's right, So

(07:58):
thank you to everybody who participated in this exercise in speculation.
If you would like to similarly speculate for our podcast,
please write to us two questions at Daniel and Jorge
dot com. So think about it for a second. Do
you think you can have matter that's not made out
of particles? Here's what people had to say. So, I
think that we don't actually know if dark matter is

(08:20):
made of particles, so dark matter may not be made
of particles. And also if there's something that makes up
the particles understandard model, then probably the particles themselves are
not made of particles. Well, nobody really knows what dark
matter is, so I guess that might be something that's

(08:43):
not a particle. The only other thing I can think
of is something like strange matter. My initial assumption is
that baryonic matta has to be made of particles, maybe
I think, but maybe not like dark matter, because as
I understanding, we have no idea. We have no idea.
By the book, I'd say that all matter that we

(09:04):
deal with on a regular basis is made of particles
like quirks and protons and electrons. But maybe dark matter
if you really consider that matter, dark matter, and dark energy.
So far, all of the matter we know these metal
particles actually feels but let's not get into that. We

(09:27):
think that the dark matter should also be metal particles,
but we haven't found any of that kind yet. So nope,
I don't think there is any matter that's not metal particles.
Matter by definition is a group of particles, So there
cannot be any matter and not made of particles. All right,
some pretty technical answers there. We have a pretty educated audience,

(09:51):
Yes we do. Good job listeners. A lot of folks
are keen in on this question of dark matter, so
good job. Yeah, and they even talk about pretty cool
neat like strange matter is that a thing. Strange matter
is a thing. It's matter made out of strange quarks.
We had a whole podcast about that and strange stars
that might be filled with strange matter. It's pretty awesome,

(10:11):
but it's definitely made of quarks, which means it's made
of particles. Even strange matter is made out of works
made out of little strange particles. It's pretty strange. So
I guess the question is, can you have matter that's
not made out of particles? And so um maybe steps
through here, Daniel. Is everything we know about made out
of particles so far, so far, everything that we've been
able to understand has been made out of particles. So

(10:34):
set aside dark energy, and set aside dark matter, and
focus on just the five percent of the universe that
science has been studying for the last few hundred years.
That portion of it, the stuff that's made out of atoms,
All of that is made out of particles. Right, So
I made out of atoms, and you're made out of atoms,
and stars are made out of atoms, and gas and

(10:55):
dust and and everything that we see and all that
stuff we're familiar with that's all made out of atoms.
And then you break those atoms apart, and you have
protons and neutrons and electrons flying around them. Break those
protons and neutrons apart, and inside them you have corks.
And that's as far as we've gotten. But everything that
we know, everything you've ever eaten, everything you've ever stepped on,

(11:17):
everything your little brother ever through it, you across the room,
has been made out of atoms, which means it's been
made out of particles. Yeah, all the stuff you can
see and touch, And it's even more amazing that even
the act of touching something is also made out of particles,
Like forces are also made out of particles. Yeah. The
way particles talk to each other is with forces. And

(11:38):
you can think about the way that happens in two ways.
One is having fields. You know these fields that every
particle has, like an electron has an electric field. But
another way to think about those fields is in terms
of particles. Like what happens when two electrons get close
to each other is they exchange photons. They shoot photons
at each other. A changing electric field is a photon.
Of photon is a way of carrying information and about

(12:00):
an electric field, for example, And so even your fridge
magnet uses photons to communicate when it moves and everything.
All particles shoot other particles at each other to push
to pull, to do any kind of communication. So it
really is a particle universe. I was just wondering, is
even energy made out of particles? Is energy made out
of particles? While that's an awesome question, you can imagine

(12:22):
it to be made out of particles in some context,
like light is a form of energy, and that's definitely
made of particles. When you think about heat, for example,
that's the vibration in you know, the crystal lattice of
a solid. We talked about how you can think about
that in terms of virtual particles like phonons and rotons,
and so in lots of cases, you can understand energy

(12:43):
in terms of particles, usually when it's discreete usually when
it's like quantized, and that usually happens when something is
confined or contained in some way, it's in a solid
or it's in a system. When things are just flying
out in space, just raw energy that it's harder sometimes
to think about in terms of particles. So I guess
energy doesn't have to be made out of particles, that

(13:03):
it can be any value. I'm trying to think about
an example of energy that isn't quantized, where it could
be any value, and I suppose you could think about
like an individual photon photon flying through space. It is
a particle, but it can have an arbitrary amount of energy,
all right, But you can only have one or two photons,
so that's still a particle. But another example is dark energy.

(13:26):
Dark energies most of the energy in the universe, and
we have no idea what it is. It might be
some new kind of field, might have a particle associated
with it, but we really just don't know. So it's
kind of strange then that you can have energy and
that's not made out of particles, but then once it
gets transformed into mass, then it does then to clustering

(13:47):
little bits. Yeah, And one thing to realize is that
particles is sort of something we do. It's a way
that we have to understand the universe. It's like something
we have done to organize our understanding, the experiments you've done,
and our thoughts about the way things work. There might
be other ways to think about the universe to explain
the phenomena we've seen, not using particles as sort of

(14:08):
a mental picture. If you talk to people in philosophy,
you know, they recognize that what we're doing in particle
physics is sort of building mental models which may or
may not reflect what's actually happening deep down in the universe.
I see, it just sort of looks like particles to us.
But maybe if you drill down even deeper, maybe you
could even get rid of this idea. Yeah, And there's

(14:29):
actually divide in the field about whether particles are the
more fundamental thing or whether fields are the more fundamental thing.
Like on one hand, people say, well, particles, they're just
like excitations of a field. The real fundamental thing in
the universe are these quantum fields that feel space. And
what is a particle? It's just like a place where
that field is wiggling a little bit, a little bit

(14:49):
of energy in that field. As you were saying, other
people say, no, no, no no, fields, you don't see them
ever directly. They're not the real thing. It's particles that
are real and fields are just another way to to
talk about virtual particles. So this sort of a division,
like what is the most fundamental thing in the universe?
Is it fields or is it particles? So I guess
if you ask the field people, then they will tell

(15:10):
you that most of the matter in the universe is
not made out of particles. It's made out of fields,
which are not quant Yeah, they would say that, you know,
particles is just a special case of a field. The
real thing in the universe is fields, and sometimes you
get energy in them, and then energy can move around
and like discrete units ensure you can call that a
particle if you like to. But I really just like

(15:31):
to think about the whole field. Why focus on the
one individual particle? And we started from the particle picture
because we found particles, like you know, J. J. Thompson
more than years ago, we found this electron started to
think about things made out of tiny little bits of
sort of a natural ideas, definitely a more natural idea
than imagining that everything which is like an excited state
of fields that fill the universe. And so yeah, a

(15:53):
person who thinks that fields of the fundamental thing in
the universe would say, particles, they're just like, you know,
they're a step along in the way. There's nothing real
about them. So well, I guess is that how you
would define it? Is like when a field gets excited
and wiggles and it sort of gets a little bit
of a bump there. Well, this is the deep, dark,
dirty secret of particle physics, which is that if you ask,

(16:15):
like five particle physicists what is a particle, you might
get five different answers. Right, So nobody even really agrees
on what it means to be a particle. You know,
you have the experimental people who say, well, I don't
know what you want to think about them theoretically, but
I know that I shoot one at another one, and
I can measure how they bounce off each other. So
it's this thing in my experiment. Somebody else might say, yeah,

(16:37):
it's just an excited state of these quantum fields that
I use in my calculations. And a mathematician might say, well,
I can use this group theory to describe the transformation
from one thing to another place in space. So really,
particles are like a physical manifestation of a mathematical construct,
you know, or a string theorist might say, a particles,

(16:58):
that's way too big. You need to do much deeper
and think about like the tiny vibrating strings that make
up everything in the universe, including particles, including fields. And
so nobody even really agrees about what a particle is.
And it could be that they're all right, right, Like,
it could be it's not that they're all wrong, or
that one of them is right and the rest of wrong.
It could be that you know, a particles, all of

(17:20):
these interesting things. Yeah, I think most likely they're all
right and they're all wrong. You know, particles are definitely
something weird, and why we're struggling is because there's something
new to us. They're not like anything we've experienced before.
And what we're doing all the time and physics is
trying to describe the unknown in terms of the known,
and so we're making analogies where maybe it's like a string,

(17:42):
maybe it's like a tiny little grain of matter, maybe
it's like waves in the ocean, and all of these
analogies fail because particles or whatever it is that makes
up the universe are fundamentally different from anything we know.
And so you know, they're all like successful in one
respect and unsuccessful in an another. And if we ever
do gain a true deep understanding of the nature of

(18:04):
the universe at its lowest scale, we're going to discover
why that is. Like, oh, it's this other weird thing.
And sometimes it does look like a particle, and sometimes
it does look like a field, and sometimes it does
look like a string. Sometimes it does look like something
that's none of those things. So I look forward to
the day that we have a deeper understanding of the
nature of the universe and we discover how all of

(18:24):
these ideas fit together into that larger picture. Yeah, and
you might be right and wrong at the same time.
It sounds like a pretty indefensible position. I'll be quantum right.
All right, Well, let's get into whether or not matter
can be made out of not particles and whether or
not we know that any such matter exists. But first
let's take a quick break. All right, we're asking the question, Daniel,

(18:59):
whether not matter cannot be made out of particle This
is a really strange question to ask Grammatically, I guess,
can matter be made out of non particles? Or can
matter and not be made out of particles? It's a
strange grammatical conundrum. How we're going to answer the science
question If we can't even get past the grammar question, right, Well,

(19:20):
we can just say we're right and wrong. It's both
grammatical and ungrammatically. We span the space of all possible answers. Yeah, now,
this is a really fun idea. I like to think
about it as non particle matter or not particle matter.
But it's actually a phrase for it now in the
theoretical physics community, they call it unparticle matter. And how

(19:41):
is that different than non particle matter? I don't know.
I think it's just fun to use the word. And
it sounds like the opposite, or like it's anti in
another way, different from anti matter. I see you sound hipper,
you know, when they make the science fiction movie about it,
I think the focus groups are gonna think that's got
like more of an edge to it. It's like conscious uncoupling.

(20:02):
It just sounds you know, more inspired or trendy. Yeah,
or it's just more mysterious. But it's a fun idea
and it's something people have been thinking about for like
the last and fifteen years seriously, Like, can we figure
out a way to talk about matter so that it's
not made out of particles? I guess maybe a first
question is what would make something qualify as matter in

(20:22):
the first place? Is it that it has mass or
that it feels gravity? What would be the specific definition there?
Boy man, this is a deep episode. If we're going
to talk about what matter even means, I think it
needs to be some sort of localization of energy. And
you know, I would say mass, because usually that implies
having a mass, but a photon, for example, is a particle.
I don't know if you would actually call a photon

(20:43):
to be part of matter, but it has energy and
it's you know, it's a localization of energy that moves
through the universe. It's consistent, it's discrete, it transformed in
ways that makes sense. But here I think we're trying
to talk about matter in the sense of things that
have mass, because really this is motivated by not understand
ending where most of the mass in the universe is
coming from, what it's made out of. So I think

(21:04):
we should talk about, you know, stuff, things that have
mass to them, that have substance, that have gravitational energy.
So I guess that would be a good definition. Is
that it feels gravity or are you talking about like
whether it's hard to move or to push it or both? Yeah? Both.
I mean, I think we can accept Einstein's equivalence principle
and suggest that inertia and gravitational energy are related. And

(21:28):
so we're looking for how to build some stuff something
that has mass to it that changes the shape of
space around it, but it is somehow not made out
of tiny little particles like a blob. When you look
at it closer, it doesn't resolve into little bits, like
it's just stuff that's there, but it has mass exactly.
And the technical phrase for this is that it's scale invariant,

(21:48):
and what that means is that as you zoom in,
it never looks different, like you look at matter under
the microscope. And if you imagine cranking of a microscope,
you have some super powerful one. You could crank it
up really powerfully. You would eventually see that the cookie
or whatever it is that's under your microscope is not smooth,
but it's made out of tiny little bits. You can
actually see the shape of the atoms and the crystal

(22:11):
lattice that formed them. But non particle matter or unparticle matter,
whatever this is, this blob would always look the same
under your microscope, no matter how much you zoomed in.
It would always look kind of fuzzy, I guess, like
a liquid. It would always look kind of smooth. If
you like mathematics, you can think of this as related
to fractals. You know, fractals are these patterns which have

(22:31):
structure to them. They're not totally smooth, but as you
zoom in you just see more and more of the
same structure. It's not like you zoom in past a
certain scale and then that's it. You found, like the
base lego unit it's made out of As you zoom in,
you just keep seeing more and more structure. All right,
So then what are some ideas for this, Like theoretically,

(22:51):
what are some possibilities for having matter that's not made
out of particles? So in two thousand and seven there
was this guy at Harvard, Howard George, I is a
famous particle of exist He had an idea theoretically for
how you could like build this thing out of weird fields.
So you take fields which are like the things that
fill space currently. You know, we have the electromagnetic field.
We have fields for all the particles, the quarks and

(23:14):
the electrons. He said, what if we have a new field,
but the energy in this field is sort of different,
and that it doesn't come together to make a particle.
It never sort of coalesces into these discrete units with
fixed mass that you can treat as particles. So he
wrote this paper and he called it un particles, and
it sort of set the theoretical world on fire for
a few years. Really what does that mean? He burned

(23:36):
down the house, people freaked out, and also was his
far made out of particles? Well, theoretical physics can be
a little bit driven by fads. You know, somebody gets
an idea that people are excited about it, so other
people write papers and like, oh, that's exciting, and then
they write papers and the whole community sort of like
moves off in a new direction for a while because
they think, oh, somebody's cracked open a new idea we

(23:58):
can build on and we can come up with something new,
because you know, they're in a little bit stuck, like
particle physics has not figured out what the universe has
made out of. We've been sort of going in circles
a little bit for the last ten or twenty years.
Their folks out there who think everything we're doing is wrong,
we're barking up the wrong tree. And so anytime somebody
comes up with something that seems really fresh, something novel,

(24:19):
that's like creates a whole new area where you can play,
like a new kind of toy to add to your
mathematical toolkit. Then it's fun. And so people started writing papers,
and they were like hundreds of papers written about un
particles for a few years. Were they interesting or uninteresting?
They were pretty interesting, and they built on each other,
you know. They had unparticles and they had on resonances

(24:41):
and unmatter and un protons. Basically they attacked an unto
everything and everybody got a paper out of it. It
was like the I mac and iPad of the nineties.
Crazy exactly, the I particle. All right, well, what's the
basic idea? Is it like like a field that can
wiggle in any way, it doesn't have to wiggle and

(25:02):
little clumps. Yeah, exactly. And these are still quantum fields,
and so they should still have discrete units of energy
in them, and so you still have blobs of energy
that move around in the field. But you can't call
them particles because they don't have definite masses. Like all
the particles are we familiar with. We don't really know
what a particle is. But one thing we do know

(25:22):
is that particles all have the same mass. Like an
electron here is an electron there. Every electron has exactly
the same mass, and that's sort of like the identity
of the electron. So what makes the electron different, for example,
from the muan, which is very closely related but has
more mass. It's what makes the up and the charm
and the top corks different, that they have different masses.

(25:43):
And so for particles they have a fixed mass. That's
something everybody can agree on. These unparticles, they are little
wiggles in some new field that they don't have a
definite mass. You can have one of any mass, and
the mass of an individual one of these unparticles can
change as it was around And is that theoretically possible?

(26:03):
Like does it work with the math? Like can you
make us such a feel that has varying anything and
still sort of fit or play with the other fields
in your physics equations? Yeah, and that's what they got
so excited about because Howard georgia I sort of figured
out the fundamental theoretical basis for this. He put together
a field that exactly had those properties that had either

(26:25):
particles with varying mass or you can also think about
it as like particles with all possible masses, like a
spectrum of masses instead of having discrete masses like this
number and that number have a whole different set of masses.
And so yeah, he figured out like the fundamental theoretical
mechanics of how to make that work, how to do
the calculations, and think about like, well, can unparticles interact

(26:47):
with particles? What does that look like? What does the
force look like where it's admitted by a particle and
then absorbed by an unparticle. And so he sort of
laid the groundwork, and everybody else went off scurrying to
follow up on it and build other ideas on top
of it. Everyone's like, Wow, that's unbelievable. But you know,
I guess it's sort of almost feels like a more

(27:08):
natural idea. Like when I think of a field or
a field of energy, it sort of makes sense that
it can wiggle anyway at once, it can have any value.
It's almost like the weird part is that regular quantum
fields behave with particles. Why would feel that premious? The
entire universe be constrained to only have, you know, bumps
that look like electrons, and all of them should look

(27:30):
the same. Why couldn't you have electrons of different masses? Yeah? Absolutely.
I got two things to say to that. One is,
I totally agree particles are a weird idea, And I imagine,
you know, what was it like when Democratus proposed that
the universe was made out of Adams thousands of years ago.
Did the Greeks hear that idea and they think that's bonkers, man,
that's ridiculous and just sort of discarded because it seems

(27:52):
so weird and so counter to their experience. Right, And
so you're right, particles are weird. But the second thing
I have to say to that is that the universe
is weird. Right. A lot of times we've discovered things
in the universe that don't make sense to us, that
don't seem natural. We shouldn't just be on the lookout
for natural solutions to our questions, because the reason we're
doing sciences have a rigorous way to figure out what

(28:15):
the actual answers are, regardless of whether they're what we
expected or even really know how to understand. So we've
got to open our minds all sorts of different kinds
of ideas. It might be particles, it might be unparticles,
it might be something totally different. Are you saying the
universe is unnatural? It's unexpected on universe that would be
too unun in one word, the universe exactly that cancels

(28:39):
out to just the verse Yeah, we're dropping verses here,
folks were freestyle and physics, right, we are the eminem
of physics here the d n J and yeah, so
we had this new theoretical tool and nobody really understood, like, well,
what does it mean and what would it be like?
Can we figure out if these things are real? And

(29:00):
so then it sort of moved over to the experimental
side of the question. People started trying to play with like, well,
how would we find these things? What would they look like?
I can isolate them with experiments, and so that was
a lot of fun to think about. All right, well,
let's get into this idea of a particle matter and
whether or not it can even exist and whether we
have even any evidence that it can or does exist.

(29:23):
But first let's take another quick break. All right, we're
talking about matter that is not made out of particles.
Is that even possible? Could you have matter out their

(29:44):
fields of energy that can take any former shape or
any level of matterness? And if it even exists, Daniel,
does it even exist? We have any clues about whether
it exists or how could we even look for matter
that doesn't looked like particles? Yeah, we don't have a
lot of clues that it does exist, except that we
have a big unsolved mystery, right, And that's what a

(30:08):
lot of our listeners were referring to in the questions
on the street, and that's this question of dark matter.
You know, we know that the matter we've been studying
for hundreds of years is made out of particles, and
it's very well explained in terms of particles. And so
this particle picture of the universe has been sort of
like transcendent. It's like taken over the way we think
about physics and the universe and everything. But remember that

(30:30):
it just describes the tiny little slice of the pie.
And we've made this mistake many times in the history
of science of over generalizing, of understanding one thing and
then assuming that everything is the same way. I mean,
even the original discovery of particles that happened. Remember J. J. Thompson.
He discovered the electron and he thought, oh, well, maybe
this is the only particle. Maybe everything is just made

(30:52):
out of electrons. And that seems ridiculous to us. Now
we know there's lots of particles, and now I'll have
to come together. But that was just an example of
over general line thing. And it's the same over generalization
to say, look, we have all these particles. They describe
five percent of the universe. Maybe they describe everything. It
just seems like a really sort of leveraged bet. And
the other chunk of the universe is dark matter. We've

(31:13):
tried to describe in terms of particles and figure out
what that particle is, but so far we've failed over
and over and over and over again. We're well past
the point where we thought we would figure out what
the dark matter particle would be. So it's a good
idea to think about other kind of matter that dark
matter might be. Yeah, I guess there's a whole bunch
of matter out there in the universe that doesn't seem

(31:35):
to play with our kind of matter. So is that
sort of a clue. Does the theory sort of suggested?
Maybe a reason that we haven't seen it with our
particles is the fact that it's not made out of particles. Yeah, exactly.
That is definitely one explanation, and you know, we shouldn't
poop on it too much. Like there is a theory
of dark matter made out of particles, which still works.
It makes sense and and it's very well tested, but

(31:57):
we haven't found that particle. Yet and remember what we
know about dark matter. We know that there's a lot
of it, right of the matter in the universe and
all the energy and the universe is dark matter. So
we know that it creates gravity, and it holds galaxies together,
and it's shaped the whole structure and formation of the
shape of the universe. We also know a lot about

(32:18):
like it's temperature. We know that it flows through the universe,
but it's not moving really really fast because I would
change the whole structure of the universe if it flowed
around and got really smooth. And we know that it
sort of acts like this fluid. It's like a fluid
with no pressure, with no viscosity, because we think it
doesn't like bump into itself. So we have this picture
which explains everything we see if dark matter was made

(32:41):
out of a massive little particle. But we can't seem
to find that particle. We keep doing experiments looking for
that particle, you know, experiments like waiting for dark matter
to bump into a big, heavy, quiet blob of xenon underground,
or creating dark matter and colliders, or waiting for dark
matter to mash into itself and give off a tiny

(33:01):
little flash of light, and we haven't ever seen any
of those things. And all the theories we had about
this dark matter particle, a lot of them predicted we
would have seen it by now. So we're sort of
trying to get more creative about the kind of particle
it could be that explains all this stuff and all
hangs together. But a definitely an important idea to keep
considering is that maybe it's not a particle at all, right,

(33:23):
but maybe you know, just because we haven't seen it
or interactive with it, doesn't mean that it's not made
out of particles, right like it, it could be a particle.
It's just a particle that doesn't like our kind of
particle or that doesn't field all the other forces. Absolutely,
it's still very much could be a particle. It could
just be a particle that feels and no other forces
other than gravity and so basically just ignores us. You know,

(33:46):
we have this great question on the podcast last week
or so, somebody said, what would you do if you
had a box of dark matter? And I said, you know,
I would shoot particles at it because I would want
to see do those particles bounce back at all? And Essentially,
that's the way of trying to like probe it, trying
to like zoom me in on what it is. Because
shooting tiny particles that's something is sort of like using
a microscope to study it. That's what the most powerful

(34:07):
microscopes are anyway. They're like scanning electron microscopes. They shoot
little beams of particles. It's something to try to understand
the shape of its surface based on how things bounce
off of it. And that's how the original particles were discovered, right, Like,
how did we figure out that matter had nuclei in it?
Rutherford shot particles at something and saw that occasionally they

(34:27):
bounced back. So that's how you sort of like zoom
in on something and understand its nature. So we're trying
to do that with dark matter, but we haven't sort
of found anything that bounces back. It hasn't interacted with
our particles yet. But yeah, it could still just be
sort of a snobbish particle that ignores all of our particles.
In your theory, Daniel, that's not particle. Maybe it just

(34:49):
doesn't want to interact because the pandemic, you know, it's
just following good social distancing. Socially responsible particle. Yeah, but
the other explanation is that maybe it's not made out
of particles. And the reason that you know, this imagined
experiment where you're shooting a beam of particles at a
blob of dark matter, the reason that you don't see
anything is because it's made out of this field. Dark

(35:11):
matter is made out of this field of unparticles, and
so there aren't like these discrete units, these lego bricks,
which if you shoot particles at the right energy you
sort of find the gaps between them, because in the
un particle field, there are no gaps between them. There's
like an infinite number of kinds of unparticles in there,
all with different masses and sort of like filling it

(35:31):
up and to make a sort of a smooth, continuous
shape that you can't probe using particles. Wait, so how
would dark matter being not made out of particles explain
why we can't interact with it? Like, wouldn't there still
be energy and mass there for our particles to bump into.
Or are you saying that it's kind of like it
could be there and there could be energy and mass,

(35:52):
but it's so kind of spread out and smooth that
our particles don't really know what to do with it. Yeah,
it has to do with the other interaction that this
stuff has. Because remember, while dark matter has energy and
mass and so it feels gravity, that's basically something that's
negligible of the particle level, Like the gravitational pull of
dark matter on any particle is basically zero. And because

(36:13):
particles have such small masses and gravity is so weak
that we can't even understand like the gravitational effect on
a single particle. And also we don't even have a
theory of gravity that works for particles. Our theory of
gravity only works for sort of like larger objects. We
have no quantum theory of gravity, so you can't really
interact with dark matter on the particle level using gravity,

(36:34):
which is the only way we know how to interact
with dark matter. So all of these studies where we're
trying to probe the nature of dark matter are assuming
or hoping that there's some other kind of interaction, there's
some new interaction between the particles were shooting at the
dark matter and the dark matter itself. And so if
that's not true, if there's no interaction, that doesn't really matter.
If it's particles or unparticles or zoom particles or zim particles.

(36:57):
You just can't probe it using particles if it doesn't
interact with those particles at all. So it's kind of
two things. That could be an unparticle and it could
also separately just be ignoring us. There's almost like two
problems there, yeah, exactly, and we we sort of set
aside the is it just ignoring us one because if
that's the case, the whole field is hopeless. Like if

(37:17):
dark matter is something new particle or un that just
has no interactions with us other than gravity, will never
really figure out what it's made out of because gravity
is just so weak it's so difficult to use as
an instrumental tool to understand what dark matter is made
out of that this question of like what dark matter
is made out of is basically hopeless. So we sort
of set that aside because it's impossible, and we say,

(37:39):
let's assume dark matter has some kind of way to
interact with us, and let's try to look forward that
way to interact and then use that to figure out
is it made out of this kind of particle or
that kind of particle or an unparticle. Well, I feel
like maybe you're sort of saying that maybe there's stuff
out there that could just be like pure energy almost right,
because energy also sort of has mass, right, energy is mass?

(38:04):
Energy does bend space like mass does. And are you
saying that maybe this on particle matter is basically just
like a buzz of energy or localized energy. Yeah, exactly,
It's more smooth and continuous than localized. If you like
to think about particles, you can imagine as made out
of lots of particles, all of different sizes, and so
that no matter how you zoom in, it always sort

(38:25):
of looks the same. But you can't really like break
off a piece and say here, I have one of them, right,
The mass of the particles themselves sort of always changing,
and so yeah, it could be that dark matter is
made out of this new, weird kind of stuff that
can't be broken off into these separate lego pieces, but
instead is made out of these like weird kinds of
bits of stuff that are constantly changing what their mass is. Wow,

(38:49):
it's undecided. It's difficult to grapple with. And I can't
tell if that's because we've spend so much time thinking
about the universe has made of particles that it's hard
to think about something made of anything different, or if
it's just because it's difficult to think about mathematically cool,
Well all right, well, so where is the field right now?
Like you said, it was popular back in the early

(39:11):
two thousand's and there was a lot of buzz and
a lot of people were blown away. But where is
it now? Do we have any progress or results? I
guess you could say we have some un results. People
have figured out how unparticles could be made in colliders.
So you smash two protons together, and if those protons
have some interaction with this unparticle field, then it could

(39:33):
deposit some of that energy into that field. And you know,
particle colliders were used to making new particles. In this case,
we'd be depositing the energy into the unparticle field. Make
this like you know, localized blob of stuff which you
can't call a particle, but you might still sort of
get a clue that it exists in our detector in
the same way that you can see invisible stuff in

(39:54):
our detector. Because it bounces off of visible stuff. You
might like create some particle and some un particles and
they shoot off in opposite directions, and by seeing the particles,
you can infer by a conservation of momentum that the
particles must have been there. So people figured out a
way that this could be produced in colliders and you
might be able to get a clue that it had happened,

(40:15):
even if you can't see the unparticles directly. And we
looked for them and we didn't see them, so so
far there's no experimental evidence that particles are a thing
or that they exist at all. And theoretically the field
sort of moved on. There was this like big flurry
of papers in two thousand and seven, two thousand and eight,
two thousand nine, and then everybody sort of got tired

(40:35):
of the idea and they moved on to some new idea,
and there haven't really been a lot of papers about
it recently. I guess you would expect to see it
in a collider, like if you collide to particles and
some energy just kind of magically disappears, right or like
you know, if energy disappeared in varying quantities, because I
think right now, when you smash particles you always get

(40:56):
kind of these discrete or you can account for everything,
and everything seems to fall into these neat boxes. But
if you found it, you know, energy sort of disappeared
at weird grates, then you may be like, oh, maybe
there is a field out there that can absorb these
varying energies. Yeah, that's exactly right. And so we're looking
for is something out there which is invisible, right, but

(41:17):
absorbs our energies to the energies you say, seems to disappear,
and it would operate differently from other fields that we
know about their invisible, like neutrinos or or other things
where we know energy can disappear into because as you say,
those are particles and so they're discrete in a certain way,
and sort of the statistical spectrum of what these results
would look like is different for un particles and for neutrinos,

(41:38):
just for that reason. All right, Well, it sounds like
we have no evidence for un particle matter, but we
can completely rule it out yet, right, that's right, we
can't completely rule it out. And I think theoretically it's
a great exercise. It's the kind of thing we should
be doing, stretching our minds and making sure that we're
not too focused on one sort of category of ideas.

(41:59):
It could be that we look back on physics and
a hundred years and say, man, those guys spend a
lot of time going down, you know, a wild goose
chase and looking for the wrong thing before somebody sort
of pulled their head out of the stand and said,
hold on a second, what about this other idea we
haven't thought about in a couple hundred years. Has anybody
really worked on that? Yeah, but that's kind of how
science works, right, Like you have to you know, follow

(42:21):
your gut for a while, sometimes in one direction, before
you either find out that it's a dead end or
that you were onto the right thing. Yeah. Absolutely, And
that's why sort of at the highest level, science needs
to have diversity of ideas. You know, we need people
following the hottest, sexiest, best idea we have so far,
but we also need people nurturing crazy ideas, stuff of

(42:41):
the fringe, stuff which might eventually become something mainstream and
really useful, but today is sort of like, I don't know,
what does that really work? And so that's why it's
important to sort of have breadth in our ideas as
well as depth of exploration. Yeah, well my money is
still on sucks Daniel, Although I have a new theory
on socks or non socks. Socks. Yeah, next time I

(43:04):
tell my kids to put socks on, they're gonna say,
I'm already wearing in socks. What do you need? There?
You go, it's the original sock. All right. Well, that
was pretty interesting and it sort of makes you question
the nature of matter in existence itself, you know, like
what we think of as things we know and what
we know what they're made out of, could not be

(43:25):
true for maybe the rest of the universe. We are
still just in a small corner of it. Yeah, And
that's the exciting thing about exploring the universe is the
surprises is discovering the universe works differently from the way
you expected that. There's a whole new way of thinking
about the very nature of matter and how the universe
is put together. That's in our future. Maybe it's five
years from now, maybe it's fifty years from now, but

(43:47):
eventually we will figure this out and we'll have a
new way of thinking about our place in the universe.
It's like many people who don't wear socks, You're like, what,
how's that even possible? Don't your shoes smell after a while?
Who knows. Yeah, we're in southern California, sandal wearing people.
We don't even buy socks. You go all right, Well,

(44:07):
thanks for joining us. We hope you enjoyed that. See
you next time. Thanks for listening, and remember that Daniel
and Jorge Explain the Universe is a production of I
Heart Radio. Or more podcast from my heart Radio, visit
the I heart Radio app, Apple Podcasts, or wherever you

(44:30):
listen to your favorite shows.