What is space?

Daniel and Kelly wrestle with the the fabric of the Universe itself. What is it, what can it do and why do we have it?

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Episode Transcript

Speaker 1 (00:06):
Some of the deepest mysteries of the universe are so big,
so imposing, so important that even asking questions about what
they are and how they work it can leave us confused.
That's because we have to spend some time thinking about
what exactly we're asking and what kind of answer we want.
But we shouldn't shy away from these kinds of questions

(00:27):
because they are the most important questions. Understanding the nature
of our reality means understanding the context of our lives,
where we live, how we live, maybe even why we live.
And what the universe has taught us is that it
always requires persistent, careful effort to unpack the deepest mysteries.
We have been chiseling away at the rock face of

(00:49):
physics for thousands of years, mostly cluelessly, but occasionally a
great hunk of understanding will open up and will see
everything in a new light. So it's worth asking the
biggest questions, the ones where the question itself can be confusing,
because looking for answers might eventually help us figure it
all out, or help us realize we're asking the wrong question.

(01:12):
So today on the podcast, we're going to dig deep
into what we know about maybe the most basic question
about the universe. We'll be asking what is space.

Speaker 2 (01:37):
Welcome to Daniel and Kelly's Extraordinary Universe. Today we are
talking about what is space? And I am Kelly Wienersmith,
and I take up space. How about you?

Speaker 1 (01:49):
I'm Daniel Whitson. I'm a professor of physics, which means
I probably should understand something about space.

Speaker 2 (01:56):
I'm going to start with a confession. So, like when
I was in high school and college, I did really
well in physics. I was in the honors classes, I
got a's. I really liked the stuff about circuitry. But
whenever we would talk about what is space or what
is time? I would feel very frustrated because like you
were taking this thing that I felt like I could
work with in my day to day life, and it
felt like it was being made unnecessarily complicated. And I

(02:20):
think I also felt a little insecure because it's like
I can't even understand what is space, and I think
it just made me frustrated and I would kind of
shut down. And as an adult, I feel different about it.
I think it's interesting. I think thinking about it creates
like testable predictions that teach us about the universe and
then we can do practical things with that knowledge. But like,
what was your journey along questions like this? And am

(02:41):
I the only physics student in classes who isn't like, oh,
this is fun and is like, no, I knew this,
Why are you doing this to me?

Speaker 1 (02:49):
I think that's a whole spectrum of people in physics,
and I think it's a big tent, and I'm glad
there are people who are like, hey, look, this gives
us tools so that we can calculate how our cannonballs
fly over castle walls. That's really all we care about,
So let's just do that and move on. And then
there's the folks on the sort of philosophical side of
things that really want to understand why balls fly over

(03:10):
castle walls because they have deeper questions about like why
is there anything and how does it all work? And
the amazing thing about physics is that it not only
lets you do practical stuff bill transistors and iPhones, but
then you get to turn around and ask like, well,
why does this work at all? And what does that
tell us about the actual universe we live in? So yeah,
touches on like technological, fascinating, useful stuff all the way

(03:33):
to philosophical stuff, and yeah, I always found myself sort
of on the philosophical side of things, and I was
the kind of kid who was like, whoa, what is
space anyway? Man? And this is before I smoked any
banana peels. I was wondering about what would it be
like to live in space that was four dimensions or
two dimensions? And why is it that we can only
think in three dimensions? So for me, these questions were

(03:53):
cat in it, even though I didn't understand anything about them.
And it's only now as a professional physicist that I
understand why we don't understand anything about them.

Speaker 2 (04:03):
I hope that we can get to that in the
show today so that the people like me who are
just like, well now you've just made me confused, have
a better sense of why we're asking these questions and
why they're fundamentally important and not just physicists making things complicated.
Like every once in a while, I'll be like, well,
we haven't married relativity and quantum mechanics, and so what

(04:25):
if when people say like space bends and time is blow, Like,
what if none of that is true because we haven't
married these things, And so then why do I have
to do this, and then I get super frustrated, and
I don't know, maybe I shouldn't be so negative. At
the beginning of our show. I'm not actually negative, like
I'm excited about it, but I'm remembering Kelly from the
past feeling very frustrated about this stuff.

Speaker 1 (04:46):
Well, I think we're going to be aiming today's episode
at Kelly of the past, somebody who is curious about
how the world works but doesn't want like a wall
of confusing language where words suddenly mean things that they
didn't mean before. And let's remember that that's the whole
project of physical We take the world that we kind
of understand we've been living in any way, and we
try to systematize it. We try to say, well, you know,

(05:07):
at what angle will your cannon ball fly over the
council walls? And do you have to factor in the
wind resistance? And then we get to turn around and
be like, well, why does this work? What does that
tell us it? Lets us do something which I think
is really awesome. We just peel back that layer of
intuitive reality and say, hey, we thought the universe was
like this, Actually it turns out it works like that.
The universe is different from the way we thought it was,

(05:28):
and that's wonderful. That's the incredible experience we're going for
in physics. We want to pull the veil from our
eyes and figure out how the universe actually is. I
think what we'll discover today is that, wow, we really
just don't know that the universe works. But it's important
that everybody understand what we do know and what we
don't know about these really basic questions about the nature.

Speaker 2 (05:48):
Of the universe, right And if you stop asking the questions,
then you never get to the answer. So it's important
to keep.

Speaker 1 (05:53):
Going exactly and that thing. It might be helpful for
people when we're talking about something as fuzzy and difficult
to grapple with a space to think about like what
kind of question we're asking and what kind of answers
are satisfactory? You know, because when we ask a vague
question like what is space? What are we really asking
when we say that? Even so often in philosophy, I
replace a confusing word with something familiar, like replace the

(06:14):
confusing word with an elephant, and think, what does the
question mean if I'm talking about an elephant? You know,
So if somebody asks you, hey, what is an elephant.
You know, what kind of question is that? What kind
of answers do we expect to that kind of question?

Speaker 2 (06:26):
When I was reading through our outline today, one of
the things that got me excited was thinking back to
grad school and when we would talk about behavior and
we'd be like, well, what is the behavior? And there's
like at least four different ways to think about it,
you know, like how did it evolve? What neurotransmitters make
this behavior happen? What things that happened beforehands initiate the behavior?
And so in the case of behavior, there's a lot
of different answers you could have for that question. Is

(06:48):
it the same for space? Are we looking for like
an equation? So yeah, like what would make a satisfying
answer for something like this? Or are there lots?

Speaker 1 (06:55):
No, You're right, what we're looking for our answers to
questions like well what can space do?

Speaker 3 (07:00):
Right?

Speaker 1 (07:00):
Like what is an elephant? Well, an elephant has big ears,
it does this thing? Right, you can describe it, You
can describe what it does. You can also ask like, well,
why is there space? You know the same way you
can be like why do we have elephants? You know,
there's a story there that tells us something about elephants
the relationship to other living things. Right, we can also ask, well,
what is space made out of? Is it itself the

(07:20):
fundamental thing in the universe where like you just got
to have it, you don't have universe without it? Or
somehow like elephants and ice cream, does it emerge from
the workings of other little bits deeper inside it that
somehow weave themselves together to make this experience we call space.
That's what I was referring to earlier, where in that scenario,
you're like pulling back a layer of reality understanding what's

(07:41):
going on underneath. So you discover that your experience is
not like fundamental, it's just sort of like one thing
that the universe can do. It can make elephants, it
can make ice cream, it can also not. So those
are the kind of questions I want to know the
answers to about space, like what can it do? Why
do we have it? Is it itself made us something smaller?
Or is it fundamental? Is it a requirement for the universe.

Speaker 2 (08:03):
So one of the things that I was worried about
when we started talking about this question was the word
space has been used by so many other fields that
now it's not confusing from a physics perspective, it's just
confusing because humans use that word for lots of different things.
But I think I was definitely proved wrong there because
when you asked the audience to tell us what they
thought space was, nobody was like, well, space is the

(08:26):
literature on space, and like everyone got it. I guess
they know us well enough to know what we were
probably talking about. So let's hear what the listeners had
to say.

Speaker 1 (08:35):
That's right, And if you would like to participate in
the audience participation segments of this podcast, please write to
us to questions at Danielankelly dot org. We will set
you up and you can hear your voice speculating basistly
on the podcast. Here's a bunch of people answering the
question what is space.

Speaker 4 (08:53):
I don't think that space is a real thing.

Speaker 1 (08:54):
I think that space is just an abstraction.

Speaker 5 (08:56):
Perhaps space is a medium in which fields can exist,
that has shape and perhaps has density and can change
in its form. Space is like an invisible lattice, geometric framework.

Speaker 1 (09:17):
Or other diffuse concept that is just a name we
give our experience.

Speaker 2 (09:22):
The composite of all energy fields, gravitational fields, and dimensions.

Speaker 4 (09:28):
The medium that we are traveling through. It's like combining
the trajectory of the Earth of some galaxy.

Speaker 1 (09:35):
Universe. Space is that which matter can move within.

Speaker 3 (09:41):
Space is the background fabric of the entire universe.

Speaker 4 (09:45):
I think to think of space as a huge collection
of spots that can have multiple states of excitement, and
the excitement of a spot interferes with its neighbors.

Speaker 1 (09:55):
The replacement or nothing.

Speaker 4 (09:58):
A physical meta that we can experience and move around
and in which events occur that we can observe and
try to understand.

Speaker 3 (10:08):
Space is this kind of thing in which everything happens,
but we can't see or feel it. We can only
see the evidence of it.

Speaker 1 (10:20):
I think this is outdated now, but I still just
think of spice as a volume that we can put
stuff into.

Speaker 4 (10:25):
I think space used to be seen as like a
substrate where everything happened on or within, But I believe
now space is kind of understood to be the thing
that is happening.

Speaker 2 (10:36):
So none of the people who answered the question were
like Daniel, I hate you, or like Daniel go away,
So it seems like everybody was, you know, enjoying thinking
it through and giving you an answer, and we got
some pretty good answers. So maybe the world is not
filled with angry young versions of Kelly, which is great,
would be better. I was also like a goth chick
covered in black all the time. I've cheered up a

(10:58):
bit too.

Speaker 1 (10:59):
I want to see when those pictures at some point.

Speaker 2 (11:01):
All right, I'll share one with you, but not with
everyone else. So, yeah, what did you think of these answers?

Speaker 4 (11:06):
Yeah?

Speaker 1 (11:06):
I thought it was good. And I also love hearing
people grapple with a hard question.

Speaker 3 (11:10):
You know.

Speaker 1 (11:10):
It's the kind of thing, as you say, everybody's got
some intuition about what space is because we live in it, right,
and yet it's difficult to say, like exactly what is
it and where it comes from a lot of people
described what it can do, right, or it can hold,
you can have things in space. So I think those
are all fine ways to approach this problem. But I
hope by the end of the podcast we give people

(11:30):
a really comprehensive view of like what physics says about
space and all the different, confusing, contradictory things the physics
says about what space might be.

Speaker 2 (11:39):
All right, So then what do you think is the
best place to start. So to me, I'm just like
I don't know space. It's like there's like stuff in
front of me. But if my table is there, it
still counts as space because my table's just like in
the space. And to be honest, that I think is
most everything I've thought about this question. So where do
we go from here?

Speaker 1 (12:00):
Maybe the best place to start is to try to answer,
like what is we're asking about? You know, when we
say space, what do we even mean by it before
we talk about like where it comes from and how
it works and what the rules are and what physics
has learned, Like what is the thing we're asking about?
You know, let's at least pinpoint the elephant here. And
you know, in my mind, space is not about the
stuff in the universe, It's about what's underneath it. It's

(12:23):
about the underlying fabric. So like, take a chunk of
universe wherever it is, and remove everything you can remove,
so it maybe there's a peanut in the universe, toss
that out, Maybe there's a planet there, toss that out,
Maybe there's a galaxy whatever, pushed out all to the side.
Empty it as much as possible, right, because the thing
we're not talking about is like particles and matter and

(12:43):
photons and stuff. Let's talk about what's underneath it. That's
really what's exciting to me about this question is that
we're like digging under the carpet of the universe, right,
And so to me, space is what's left when you
remove everything that you could remove from a portion of
the universe.

Speaker 2 (13:00):
So, like in my office right now, and if we
were to try to figure out what space is in
terms of my office, we'd turn it into a vacuum.
So I should leave my office if we're going to
do this experiment, like we take everything out, and now
we're asking what are we left with?

Speaker 1 (13:15):
Yeah, well we'd have to take you out because you're
not space right your stuff? Yeah, so yeah, remove all
the stuff what is left? And that opens up immediately like,
well is there anything left? Does it mean anything to
have space there without stuff in it? Is space just
defined to be the place between stuff? Or is it
a thing itself? Right? Is space a kind of stuff? Right?

(13:37):
I Mean, I know we're getting like really banana pels
behind the gym over here, but these are the questions
we're grappling with, and to me, this is what's exciting
about physics is that these questions are really fuzzy, and yeah,
you could you know, smoke banana peels and talk about
them all afternoon and really make no progress, or for
thousands of years and make no progress. But physics gives
you a way forward. Physics gives you this method to

(13:58):
like understand your intuitive experience and make it make sense
by asking, like, can we build a model that describes
what he can do? And then can we look at
that model and say, like, what does that mean about
what it is? So to me, the reason I'm a
physicist and not a philosopher is that we can't actually
make some progress if we think about it like mathematically
and systematically.

Speaker 2 (14:17):
Okay, so we've now gotten to like you've removed everything,
so you've got a vacuum, and now I feel like
there's a vacuum in my brain and I'm like, well,
where do you go from there? How does physics tackle
this question?

Speaker 3 (14:27):
Then?

Speaker 1 (14:27):
Physics thinks about space in terms of location and motion,
because what do you have left once you've emptied your office?
There's just space there, which means the possibility to put
something in it. Right, you can put a proton in it,
But The interesting thing is you can choose where to
put the proton. You can put the proton where Kelly's
desk used to be, or you could put the proton
where Kelly's head used to be. Those in principle are different, right,

(14:51):
And so space offers us these choices. You can be here,
you can be there. Space seems to have inherent in
it this like location, right, and and those locations can change. So, like,
very very early on, before we were doing science, the
way we think about it science, you know, the Greeks,
they were thinking about space in terms of change, like

(15:11):
motion and change. So the way physics begins attacking this
problem is like why are there locations? And what are
the rules about locations? Like how do things go from
here to there? And why is here different from there?
And can you tell the difference between here and there?

Speaker 2 (15:24):
In my head? Right now, I've got like a three
dimensional graph, and you identify space as like a point
on that graph, and does it stay there forever? Or
does space move? Or have you just jumped to a
different point on the graph?

Speaker 1 (15:40):
Yeah? Right, great questions right, like are we moving relative
to space? Can you measure our motion relative to space?
Or can we only measure our motion relative to like
other things in space. Right, that's an early basic question,
and this is the kind of thing Aristotle was thinking about.
Aristotle was like, well, you know, why do things move
move at all? Wasn't everything just like stay the same

(16:02):
place you put a proton? Wasn't it just stay there forever?
And of course he was working on the surface of
the Earth, and so he noticed like, hey, things fall down, right,
Why do things fall down? Why do things seem to
move through this space? And so you see that, like
very early on, the questions of space and motion were
tied together. And you know, Aristotle didn't have like a
mathematical picture of how the universe worked or how anything happened.

(16:24):
He was sort of like words based, you know, it
was like vibes based signs. And he just basically said, look,
things fall down because things move according to their nature.
Matter tends to fall down. That's just it's sort of
like a descriptive. It's not really explanatory. He's just like,
stuff falls down because it's in the nature of things
to fall down. Such a circular answer. I don't even

(16:44):
know why it was ever satisfactory.

Speaker 2 (16:46):
So we were talking about the absence of stuff, and
now we're talking about the movement of stuff, and so
the connection to space is that space is standing still
while the stuff is moving, or just that this is
the first time people have thought about the relationship between
space and stuff.

Speaker 1 (17:03):
Yeah, I think all of that early on people trying
to figure out what space is by understanding how things
move through space, like what does it mean to go
from here to there? What does it mean to fall down?
And why do things fall down? Anyway, and it gives
you a handle like what does speed mean? But you know,
Aristotle's view of what this meant was basically the way
people thought about it for thousands of years until around Galileo.

(17:25):
And Galileo was the first person to think like, well,
what do you really mean? Aristotle like, what are you
talking about things fall down? Because down seems to kind
of depend on who you are. And he had this
famous thought experiment way before Einstein was thinking about stuff.
He was like, say you're on a boat and you're
inside the boat, so you can't see the outside. You're

(17:46):
like below decks, and you drop a ball. What's going
to happen? Well, Aristotle says, the ball's going to fall down.
Anybody who dropped. Anything on a boat knows the ball
falls down. Cool, But now what happens if there's somebody
on the ground and they're watching your experiment somehow does
the ball fall down according to the person on the boat,
which means it's then moving with the boat, or does

(18:08):
the ball fall down according to the person on the ground,
in which case it would be left behind. Right, there's
actually different predictions there. If the ball falls down according
to the person on the dock, it falls like sort
of straight down, then as the boat keeps moving, the
ball gets left behind and the person on the boat
should see the ball like weirdly fall backwards. Whereas if

(18:28):
the ball falls down according to the person on the
boat right, then it falls down for them, but the
person on the dock sees it moving forward with the boat,
So you can't have it fall straight down for both people.
This is what Galleo realized.

Speaker 2 (18:41):
Okay, so my brain is now again trying to so
it feels like we're talking about stuff, but we're not
talking about space. And so the connection is the stuff
is moving through space, and by understanding the movement of
the stuff, we can understand the space better.

Speaker 1 (18:58):
Exactly because galle is experiment helps us think about what
speed means. Right, what is velocity? Are you moving relative
to space? Are you only moving relative to other things?
And Galileo's experiment and what we call Galleyan relativity is
the velocity is just relative. You're not moving relative to space.
Space is not something like grid that fills the universe
and you could just move through space relative to that grid.

(19:22):
You can only measure your velocity relative to other stuff because,
like you're in the boat, there's no experiment that you
can do to measure your velocity relative to the ground. Right,
you can drop the ball, but the motion of the
ball doesn't depend on your speed relative to the ground,
So it doesn't tell you how fast you're going. You
could be standing still, you could be going super fast.
You can't tell the difference. And you're asking like, well, okay,

(19:44):
but aren't we supposed to be talking about space? And
what this tells us is about motion through space, and
it tells us something really deep and important that velocity
is only relative to other stuff. Space is not a
thing you can have a speed relative to. So Aristotles think,
you know, the universe is filled with space, and stuff
moves through space. According to it's like natural tendency. Galleo's like,

(20:06):
nu uh uh, space isn't a thing. You actually can
just move relative to other stuff in space. So that's
already like a big clue about what space might be.

Speaker 2 (20:16):
Okay, So is it fair to summarize by being like
Galileo would say, there is no space. There's no grid
in the world, so no space. I'm guessing other people
have come to other conclusions. Otherwise that would be a
short episode. And so let's take a break and when
we come back, we'll find out if space exists. All right,

(20:54):
So Galileo telling us space doesn't exist, who are we
going to talk about next.

Speaker 1 (21:00):
I love the way you say that because I imagine
like you saying that to Galleo, and he would probably
not agree with your phrasing of it, though I agree,
you know, I think that what Galileo tells us is
that maybe space exists, but it's just the distance between objects, right, So,
like you can have space, it's just not absolute, like
it can't exist without stuff in it. The thought experiment
we did, we were like, take everything out of Kelly's office.

(21:22):
It would be like, well, there's nothing in there. Space
is not a thing. If there's nothing in there. If
you evacuated the whole universe, right, got all rid of
all the particles and all the energy and everything, then
there would be no space. I think that's what Galileo
would say, not the space doesn't exist, but that it
only exists between stuff, not on its own. It's not
like a thing on its own.

Speaker 2 (21:40):
So like if you had a vacuum and you cleared
out everything inside the vacuum, nothing exists in there, or
like you now have a space of non existence.

Speaker 1 (21:48):
Yeah, I think that's Galileo's view. But this was very
confusing to people, and folks like Newton who spent a
lot of time thinking about motion. You know, he developed
physics basically and calculus, and he thought carefully about the
mathematical flow of things, and he unified our understanding of
gravity on the ground and in the sky. He agreed
with Galileo about how velocity works, right, obviously, he wrote

(22:11):
down the equations. You know, he was the first guy
to really be able to predict these things. So he
agreed the velocity is relative, but he fundamentally disagreed about
the nature of space. He was like, no, space is absolute,
it exists in and of itself and you can have
a velocity relative to it. So Galileo's like, velocity is
purely relative, and Newton is like, I agree with you

(22:31):
about the equations and that you can only measure your
velocity relative to other stuff. But I still believe that
space is a thing underlying everything.

Speaker 2 (22:39):
So does that suggest that the things that they were
measuring are not important for understanding space because they could
get the same information and come to different conclusions.

Speaker 1 (22:49):
I think it suggests that Newton was a little crazy, okay,
because his conclusion is not supported. Like, the problem with
Newton's idea that maybe space is absolute is that you
still can't ever measure your velocity relative to it. So
he believed in this thing that existed that you couldn't
ever measure, you know, Galleo says, velocity is purely relative.

(23:10):
There's no like velocity relative to space itself, because space
itself on its own doesn't exist, right, only exists relative
to stuff. Newton is like, yeah, I agree with you
about velocity. You can only measure with between things, but
still unobservable, unknowable to us, there is this absolute space.
Even though he could think of no way to measure
speed relative to it. So Newton believed that you could be,

(23:32):
for example, at rest with respect to space, and it
was some like special frame of reference there. Gallet was like, no, no,
that doesn't exist, and plus you can't measure it. So
Newton is just sort of going out in a limb
thinking that it exists even if you can't measure it.

Speaker 2 (23:45):
All right, Well, I think just about every scientist you
talk to has blind spots where they're like, no, it's true,
and I can't tell you why, but I'm sure that
it's true. We're all human. So we've been saying the
word relative a lot, which makes me feel like we're
gonna have to get to Einstein eventually. Is he the
next person on your list?

Speaker 1 (24:02):
He's definitely the next person on the list. And Einstein
gets a lot of credit for relativity. You think of relativity,
you think of Einstein. But the truth is that Einstein's relativity,
his concepts of space really just go back to Galileo.
It's Galileyan relativity that Einstein took and just sort of
like said, hey, let's go back to this. This made
a lot of sense to me. Let's just like build

(24:23):
this in at the foundations because Einstein was thinking about light.
Only a few decades earlier, Maxwell had figured out that
light is a wiggle in the electromagnetic field. And the
confusing thing about it was that Maxwell's equation said that
light should travel at a specific speed, the speed of light,
and that it shouldn't depend on your velocity at all. Like,
no matter whether you're on the Earth that's going around

(24:44):
the Sun, or you're in a spaceship or you're just
floating in deep space, everybody should see light travel at
the same speed, said Maxwell. And Einstein was like, hey,
well that's cool. That's actually what Galileo was saying, right.
Gallea was saying that you shouldn't be able to measure
your velocity, that there's no absolute for life, the velocity
is only relative. And so what Einstein did was apply
Galleyan relativity to Maxwell's equations and say that means that

(25:08):
everybody measures the speed of light to be the speed
of light, regardless of what else you're doing. That's the
foundation of Einstein's idea. But really it's taking Galileo's relativity
and just being like, hey, let's take.

Speaker 2 (25:19):
This seriously, okay, And so all of that. Whenever you're
talking about the history of something. I feel like I
get it in my head. I'm like, oh, that makes
sense that it's like, oh no, wait, but then that
got overturned and you're like, oh, but I just understood it, okay,
And so that so all of that we still believe in.

Speaker 1 (25:36):
Right, We wait until you understand something, Klay, and then
we overturn it. That's that's the whole plan there.

Speaker 2 (25:41):
You know that I've suspected that for a long time.
But the whole world is about me and my understanding
of things. So light is always moving at the same speed,
no matter who was viewing it. That is still something
we believe.

Speaker 1 (25:53):
That is still something we believe. And that is the
earthquake of Einstein's relativity. The concepts came from Galileo, but
because he applied it to light and had all sorts
of consequences. Also because Einstein connected space and time and
we're going to talk about what time means in another
episode and what it even is. But the fact that
light always moves at the same speed for all observers

(26:13):
connects space and time in these really unique ways. And
the short version of the story is that it means
that different people have different clocks. So like clocks tike
at different speeds at different parts of the universe, and
that's a direct consequence of how light moves through space,
because everybody sees light move at the same speed no
matter what. Then you can't have clocks that all agree

(26:33):
all the way through the universe. And if you want
to know more about how that works, check out the
companion episode about what time is. We'll explain all of that.

Speaker 2 (26:41):
Now we've talked about the movement of light through space.
What does that tell us about how we can define space?

Speaker 1 (26:48):
Yeah, so Einstein's relativity means something really important about what
space is because it connects space and time, which tells
us that time is relative also not just space. Time
is relative and the same for everybody, and it has
an important meaning for what distances are between things. It
means that like I can measure the length of a ruler,
and you can measure the length of a ruler, which

(27:09):
is like the distance between two points in space, and
we can get different answers and we can both be correct.
This is something in special loyaltuty that goes by the
name length traction, and basically it just means, hey, you
assume that things have a length and have a length,
and that length is their length, and it doesn't matter
how fast you're going or where you are. Turns out
that's not true. It turns out the distances between points

(27:31):
what we even mean by space, depends on where you're
looking at them from and how fast you're going relative
to them.

Speaker 2 (27:39):
Okay, So if we want to try to understand space,
does that mean we need to try to find ways
to hold constant how fast you're moving and the distance
between things, and then we can start to get a
handle on space.

Speaker 1 (27:53):
Yeah, exactly, we want to talk about space. Space is
about the distance between things. So now we have to
think about, well, how do you measure the distance between things?
And you know, you can be pretty pedantic about it.
You can be like, well, I'm gonna hold up a
ruler between two things. I'm going to measure where thing
one is and thing two are at the same time,
and I'm gonna say, well, the difference between the marks
and the ruler, that's how far apart they are. You know,

(28:15):
I have my left hand and my right hand. I
put them on a ruler. There's ten centimeters long ticks
between them, So I say they're ten centimeters apart right.
And the crucial thing that I've done there is I've
done it at the same time. I said, I'm gonna
look at where my left hand is right now and
where my right hand is right now, and measure their
distances at the same time, and then I'm going to
call that the distance between them. The problem is that

(28:36):
Einstein's relativity and this whole speed of light business changes
what we mean by at the same time because time
is not universal anymore. So I might say I'm measuring
where my left and my right hand are at the
same time. But you might think, actually, Daniel, you messed up.
You measured where your left hand was and then a
second later where your right hand was, and if you're moving,
then now the whole measurement is messed up. So connecting

(28:57):
space and time changes how we think our clocks work,
which also upends how we measure distances, and in the end,
that's what space is about. Right We're talked about where
a proton is and where another proton is and how
far apart they are. Now it turns out, according to Einstein,
we don't even agree about the distances. That's not even
a fundamental thing about space. That everybody looks at a
distance and agrees about what the distance is, like how

(29:19):
many centimeters are there between the protons?

Speaker 2 (29:21):
Okay, so it sounds like we've decided that a definition
of space has to include distance. Yeah, but people measure
distances differently depending on their conditions. Is there a way
to get around that or no, there's no way to
get two people? I need ice cream?

Speaker 1 (29:40):
Yeah, exactly, there's no way around that. That turns out
to just be a feature of space that we never
noticed before because mostly we had basically no velocity relative
to each other, mostly slow speeds on the surface of
the Earth, and we didn't look at very long distances.
So we have this intuition that things have a size,
and that size is just what they are, and you
should measure that size no matter who you are and

(30:02):
how fast you're going. That just turns out to be wrong.
Like sometimes people ask me, you know, why do things
get shorter if you see them at high speeds. You know,
you have a ruler stick flying by you at nine
tenths of the speed of light, Why do you measure
it to be less than a meter stick? If it
was a meter when you're holding it and the answer
is not that it's shrunk there. You're imposing your like intuition,
you're prejudice that things have a size and that they

(30:24):
have to shrink to get shorter. The answer is lengths
depends on velocity. Like, that's just the way space works.
You can't escape it, Kelly, is no way around it.
Space just is different from the way our intuition work.
And this is why it's so important to explore it
like systematically and mathematically, because it contradicts our intuition and
it leads us, we hope, at least, to some true
insights about the nature of reality.

Speaker 2 (30:45):
So why can't we just say that depending on conditions,
you get different distances, but the only thing you're differing
in is how much space you're talking about. But you
can still talk about space, like why do we have
to be able to measure it to have a definition
of it?

Speaker 1 (31:01):
Why do we have to measure it to have a
definition of it? Wow, awesome question. You know. I think
that's probably because the way we do science is we
measure stuff, right, Like, you have to be able to
take measurements to have data so you can talk about
what that data means. Right, Otherwise, what are you doing.
You just smoking banana peels and having conversations, which is fine.

Speaker 2 (31:22):
But so distance isn't the only way to measure things.
Why is distance the measurement that we have to have
in order to understand space?

Speaker 1 (31:31):
Oh yeah, I see a great question. Well, I think
because we imagine that space is about locations, right, Even
if you think about space as some three D grid,
those are all locations, and so distances are differences between locations, right,
And either those are relative, like the only thing that
exists are distances between two points, two protons or two

(31:53):
ends of the ruler, or there's some absolute grid, and
you can measure your distance relative to space itself. But
in the end, distance is the thing that space is describing.

Speaker 5 (32:02):
Right.

Speaker 1 (32:03):
If you don't have space, you can't have distance, right,
And so that's sort of like the way we get
handle on space.

Speaker 2 (32:09):
This whole podcast is about Kelly understanding herself better. It's
like part Kelly Psychology, part what is space? And I
think part of why I enjoy this conversation more as
an adult is I'm way more comfortable now being like,
this is probably a really not smart question, but I
don't care. I'm asking it, and I think in its classes.
I'd just be like, no, I can't say that, because
that would be anyway. Maybe our listeners are going to

(32:29):
write it and be like, you shouldn't ask those questions.
They're not good questions, but anyway.

Speaker 1 (32:34):
Okay, they're perfect questions. They're perfect questions.

Speaker 2 (32:37):
Yes, okay, you have to have distance, but you cannot
measure distance. Where do we go from here?

Speaker 1 (32:44):
You can measure distance, it's just that the distance is
not the same for everybody. Right, that's two people measuring
the same quantities can get different answers. So distance is
not universal, but it can still exist, and then things
get crazier. Everything we're talking about so far is just
Einstein's view of how things move in sort of Newton's
idea of space. But Einstein then introduced another concept. So

(33:07):
now we go from special relativity to general relativity. He said,
space can do even more. We can change the relative
distances between things without those things moving. This is the
idea of space itself curving. And there's a lot of
descriptions out there in popular science about what it means
for space to curve, and many of them are very misleading.

(33:28):
You know, there's the famous one about the rubber sheet
that most pop side folks go to. And I really
discourage you from thinking about space in terms of a
rubber sheet, because if you think about it carefully, it
leads to all sorts of misunderstandings, you know. And so
we're going to cover the rubber sheet analogy just to
talk about why it's misleading. The general picture of the
rubber sheet is like you stretch out this rubber sheet
and then you put a bowling ball in it. The

(33:50):
bowling ball bends the rubber sheet, and that's supposed to
represent like how space is curving. The problem with that
analogy is that it's showing you to D space the
rubber sheet in some third dimension, like it's bending outside
the universe itself. The universe is supposed to be two D,
and the rubber sheet is bending into some other dimension,
whereas in our space. The way Einstein thinks about space

(34:12):
bending is it's intrinsic. There's no additional dimension. We're not
bending our three D space into some fourth dimension like
a rubber sheet bending into some new dimension we can't see.
That's not what space curvature is. It's just changing the
relative distances between things. So, like Kelly and I have
a certain number of thousands of miles between us right now,

(34:33):
what if while we both sit in our chair, you
could just change that distance, so now it's a thousand miles,
or now it's ten thousand miles. We just change the
amount of space between us.

Speaker 2 (34:43):
When I think about the curvature of space, I feel like,
but isn't there now space on either side of whatever
just curved? But I guess that area is supposed to
have no space, So there's places that have no space?
Is that right?

Speaker 1 (34:56):
What do you mean on either side? You mean like
are we getting pushed out in to other space or something?

Speaker 2 (35:01):
So I guess maybe my brain is still stuck on
the rubber sheet. So you've got the sheet, it like
goes in where the bowling ball is. But in my head,
there's space above where the bend is, Like you know,
the sheet was there and now it's down, but there's
still something where the sheet used to be, because there's
still space there. But is that not how to think
about it? Like when it bends, there's space and there's nothing,
there's like the absence.

Speaker 1 (35:21):
Yeah, exactly. That's why the rubber sheet is so confusing
because as soon as you dig into it. It leads
to questions that don't have answers because the herb sheet
is just not the way it works right. The two
D examples are useful because they are easier to think
about instead. Imagine like a map, right, so you have
your favorite country, US, Argentina or whatever, and think about
a bunch of cities on that map, and they all
have distances between them, right, and old maps you could

(35:43):
like look up how far it was between New York
and La or between Seattle and Miami, right, and those
are distances all right. Cool, And if you took a
ruler to the map, you could like measure those things
and the map would lay flat on a table and
you could measure those distances with rule. Cool. Now, what
if I came in and I had magic fingers, and

(36:04):
I'm like, I'm just going to change the distance between
LA and Seattle and I'm not going to change anything else,
or I'm gonna make it longer. I'm gonna make it
shorter that distance. Now, imagine like, does that map lie
flat on the table anymore? If I play with enough cities,
then a order accommodate having more or less space, I'm
gonna end up with wrinkles in that map. There's gonna
be no way to lay that map flat on the table.

(36:26):
And that's essentially what's happening in space. You put a
mass in space, and space shrinks, right. It changes the
relative distances between stuff in a way that it's no
longer conceptually flat in your mind, the way that a
sheet of paper would no longer be flat if you
just like magically change the distances between two points on
that sheet of paper.

Speaker 2 (36:46):
All right, So I'm thinking about the map, and you
shortened the distance between Seattle and LA. And maybe I'm
taking everything too literally, Like has San Francisco disappeared? Are
all the people in San Francisco shorter because everything has trunk?
Or are you tunneling through the map to shorten the distance,

(37:07):
or do we not know what space is doing? It
could be like any of those things.

Speaker 1 (37:10):
We're not tunneling through San Francisco, and we're not killing
anybody in San Francisco. I hope you all are safe
out there. We're just changing the distance between Seattle and LA.
We're just saying, hey, if you turn on a flashlight
in La, how long would it take for that light
to get to Seattle? Because the speed of light is constant.
This is a good way to measure how much space
there is. So we're saying, hey, these things are now closer.

(37:31):
That's what it means to shrink space. And the idea
of curvature is that it's local, right, Like you could
make everything further apart and everything closer together and keep
the map flat. But if you only squeeze two different
cities to make them closer together or further apart, then
now space has weird bends in it, right, in order
to make light take a certain amount of time to
go here and a certain amount of time to go there,

(37:52):
and to make all the light times work out, space
has to have weird curves and it can no longer
be flat in the same way that like, if you
magically made the time from La to Seattle five times
as long, then there would have to be more space
in there. You couldn't have a flat sheet of paper.
You need to like add more space, more land, more
road for you to drive on.

Speaker 2 (38:11):
We can move forward, but I have to admit I'm
having a little trouble, Like, does that mean we have
stretched out what already exists or made more? Are there
new cities in between now or did we just take
what existed and it's like taffy and wh'ere just it's
like like all the people in between are like twice
as wide.

Speaker 1 (38:29):
Yeah, okay, great question, And this is something we actually
know the answer to because we've done it. Like when
gravitational waves hit the Earth, they literally do this. They
stretch space and they shrink space. Right, So this actually happens.
And what happens when a gravitational wave passes through the Earth,
this is a wave in space itself again, which just

(38:51):
means you're changing their relative distances. What happens in reality
is the stuff that's holding us together, the land, the
electrochemical bond, keeps us at the same distance. And so,
for example, simplify things and say you and I were
out floating in space and we were holding a rod
that was one kilometer long, each holding one end, and
then a gravitational wave comes by and it stretches space. Well,

(39:14):
you and I are holding the rod, and the rod
has bonds, and so it's going to keep us at
exactly one kilometer apart, even though space is stretching around us.
So if we show in a flashlight, we would still
measure one kilometer. But if we weren't holding onto the rod, right,
there was nothing keeping us at one kilometer. Then when
space wiggles around us, we would use our flashlights and
we would measure more than one kilometer distance because it

(39:36):
would take light longer. So your question is, like, is
it making more space or is it stretching the space
that's already there. Nobody knows the answer to that question
because we don't really know what space is. Like, what
is happening you're asking, like the underlying mechanisms of all this, Yeah,
we have no idea what's really going on there. We
just have this mathematical theory that tells us how to
do these calculations. We don't know what's underlying going on.

Speaker 2 (39:59):
But the car the way we understand these things, can
it be used to like predict and understand things we've
actually seen. This isn't just smoking banana peels. We tested
these things. Our understanding is.

Speaker 1 (40:13):
Useful, absolutely, And we can measure this curvature, like if
you shine light through this space, you can tell is
space curved or is it not? Like if you shine
two parallel lines through space that's not curved. They should
never touch two photon beams through flat space should never
touch if they're in parallel, but in curved space they
will either cross or they'll split apart. Right, And we

(40:35):
have measured this, Like the famous proof of relativity from
Einstein was seeing light bend around the moon during the eclipse, right,
that was seeing light move through curved space and bending,
And so this is definitely something we've seen. We have
very accurate models, and general relativity is amazingly precise. It
predicts all sorts of things that nobody else could predict.

(40:55):
So it tells us what space does because not only
is space curved and light moves through it in curved ways,
but like other stuff moves through it in curved ways.
You have the Earth moving around the Sun because the
Sun has curved space around it. So it's not just
smoking banana peels. It works really really really well. But
you know, then we can ask like, well, all right,

(41:16):
so general relativity tells us that, like if you have
mass in space, it curves it, and that not only
our distance is relative, but like distances between stuff can
change even without that stuff moving. So like what does
that mean about what space is? Right?

Speaker 2 (41:32):
And let's dig into that question after we go all
grab some more banana peels. Okay, so you just finished

(41:56):
saying that the distance between two objects can change even
if both of the objects like perceive that they have
stayed still. But what does that tell us about space?

Speaker 1 (42:04):
So we can measure our velocity relative to other stuff,
and we can tell that space can sometimes expand and
shrink between it, and we have these amazing calculations from
general relativity, what does that tell us about what space
actually is? You know? Well, back to the conversation with
Galileo and with Newton. Einstein agrees that velocity is relative, right,
you can only measure your velocity relative to other stuff.

(42:27):
And it seems like he's saying that space is a
thing because space can do stuff like it can wiggle,
it can bend, it can expand. So we went from
like Galleo saying, now space is just the distance between stuff,
to Newton saying, no, space is a thing, even though
you can't measure your velocity to it, to Einstein being like, well,
space has interesting properties, so it's pretty hard to say
it's not a thing. Right. The weirdest part about Einstein's space, though,

(42:51):
is that you still can't measure your velocity relative to it, like,
even if you think it's out there and it has
curvature and has these properties, you can't measure your speed
relative to just space. It's something Matt Strassler calls emotional,
like there's no way to measure your speed relative to space.
So in one hand, Einstein agrees with Galleo like you

(43:12):
have velocities relative, but he also agrees with Newton like
space is a thing. But then back to Galleo, He's like, actually,
but you can't measure your speed relative to it, So
like what is it?

Speaker 4 (43:22):
Man?

Speaker 2 (43:22):
Yeah, so is this something that like when we understand
dark matter and dark energy, it could help us understand space.
Are those like just completely different problems.

Speaker 1 (43:35):
They could be completely different problems or they could be connected.
You never know what thread of investigation is it really
going to help you, like figure out what's going on
and where the next breakthrough is going to come from.
What we do know is that general relativity is a
great description of space and motion, but we don't know
what's going on underneath it. Like people often ask me,
you put mass in space and space bends. Why does
it bend? What is the mechanism for bending it? What

(43:58):
is doing the bending? And we don't know the answer
to those questions. Remember, general relativity is a description of
what we've seen, and we can look at it and
be like, well, what does that mean about space? And
it's not a final answer. And part of the reason
we know it's not a final answer is that we
have this completely separate idea about how the universe works
and how space is that comes from the other branch
of physics that we've been developing over the last one

(44:20):
hundred years, which is quantum mechanics, and quantum mechanics tells
us a completely different story about space, what it is
and how it works.

Speaker 2 (44:28):
So quantum mechanics would not agree that space bends in
the way that we've been talking about.

Speaker 1 (44:33):
Quantum mechanics has no answer to the question of what
is bending light around the moon. Quantum mechanics can't explain
space bending. Quantum mechanics can explain gravity at all. Quantum
mechanics can explain electromagnetism, it can explain the weak force,
it can explain particles that it can explain all the
strange experiments we saw right one hundred years ago and
the experiments we do at the particle collider, and it's

(44:56):
an extraordinarily accurate description of everything basically particle related. But
it's built on a different assumption about space. It thinks
of space the way Newton did, just like the backdrop
on which things play out in the universe. You know,
general relativity is what we call background free. It's like
space itself is just the distances between stuff, and quantum
mechanics is like, no, there's a background there, Just lay

(45:17):
space out, roll it out like AstroTurf, and then particles
do their dance in that space. And so it starts
from a very different place, and it can't explain how
space bends. In fact, the space bends too much, quantum
mechanics breaks down. We don't know how to do calculations
for quantum mechanics if space is super bendy. And it
also tells us something very different about empty space. Like

(45:40):
the exercise we started out with where we said, take
your office, remove Kelly, remove all of her books, remove
all of her weird samples of parasites and other gross
stuff I can see in the background, and all the air.
What's left. Well, Einstein says there's nothing there, but quantum
mechanics says that's not possible because quantum mechanics says, space
in itself is filled with fields, Like what is it

(46:02):
that light is moving through? Anyway? It's moving through the
electromagnetic field. Well, you can't take that out of space.
Quantum mechanics says, you can't like rip the field itself out.
You can say, I'm going to take all the photons out,
but the field itself is like the capacity for light
to move through it. It's like a parking lot with
no cars in it, right, the field itself is always there.

(46:24):
And quantum mechanics says that we have the electromagnetic field
and the electron field and the muon fil in all
sorts of fields that they're a part of space itself.
And not only that, but these fields can never be
totally zero. You can never pull all the energy out
of them. They have a minimum quantum fuzziness, which means
that there's always energy in space. So quantum mechanics view

(46:45):
of space is really different. It's like you have this
absolute background on which you put these fields, and these
fields are always buzzing even if you do your best
job of pulling everything out of that space.

Speaker 2 (46:56):
So are these the two main theories for space? So
there's no other like theories that physicists take seriously. I'm
sure there's plenty of people who have additional theories, but
there's no theories people take seriously.

Speaker 1 (47:08):
Yeah, we have narrated down to at least two ideas
about space, both of which we're pretty sure are wrong. Hey, no,
that's progress.

Speaker 2 (47:15):
That is No, that is progress. So does anybody have
any promising experiments designed to follow up on this next
or what comes next? We're at a stalemate.

Speaker 1 (47:25):
It seems we are at a stalemate. And one issue
is that we don't know whether the quantum mechanics version
of space or the general relativity version of space is
correct because almost every experiment we can think of only
involves one of them. Like we can do experiments to
test general relativity, like photons bending around moons, but then
quantum effects are irrelevant because quantum effects get averaged out

(47:46):
when you have something as big as a moon, Or
we can think of quantum mechanical experiments we have like
one particle bouncing off another particle, but then gravity is
irrelevant because the gravity of a particle is basically zero
because gravity is super duper weak. So the only place
you could do a test to say, like, well, whose
idea of space is correct? Quantum mechanics or gravity are
experiments that are particle sized but have the masses of moons.

(48:09):
And so now we're talking about black holes, and so
the answer to like what space really is and how
does it all work? Is hiding behind the event horizons
of black holes, like what's in there? General relativity says
it's a singularity. Quantum mechanics says that's nonsense. They can't
both be right. They could both be wrong. So, yeah,
the answer to your question is build a spaceship, fly

(48:30):
into a black hole, get the answer, but never be
able to tell anybody about it because you're chopped forever.

Speaker 2 (48:35):
Is there any reason to hope that we'll be able
to get the answer? Someday? Will our children be having
the same conversation?

Speaker 1 (48:43):
I think we probably will figure it out. There are
other ways to explore this, like the hearts of neutron
stars are not quite dense enough to become black holes,
but they are dense enough, or gravity and some quantum
mechanical effects are both important, So by studying the insides
of neutron stars we might be able to get a clue.
But there's also just a lot of like thinking that
we need to do. You know, it's not like we

(49:05):
have a great theory that predicts what's going to happen
that we need to go test. So we have some
more thinking to do about like how to bring these
things together, and there are definitely people working on it,
you know. String theory is one effort to try to
describe things that incorporates gravity and quantum mechanics. This other
approaches loop quantum gravity. One of my favorite ideas is
that space itself is made of chunks, right, like little

(49:27):
pixels of space, and that what's happening when space increases
is that you're like adding more pixels, and that when
space shrinks is that you're decreasing these pixels. The cool
thing about this is that it gives you a way
to think about a universe without space. Like imagine a
whole bunch of pixels in the beginning of the universe,
and these pixels are not tied together in any way.
It's like a pile of beads before you do your project.

(49:50):
Then somebody comes along and they weave all these beads
together into a sheet, right, or like a three D grid.
That's what space is there's a bunch of these pixels
woven together with maybe quantum forces or something into this
three D grid that we live in and experience. But
you could also imagine that there was a time before
that happened, when space was like disorganized, where you couldn't

(50:12):
let go from one to the other because they weren't
connected the way they are now. So thinking about the
nature of space and thinking about how to bring these
ideas together is maybe a fruitful way to make progress
because it forces you to think, like, well, what does
this mean, and what else could it be? And could
you have a universe without space? All this kind of stuff.

Speaker 2 (50:29):
So for the pixel theory, like when you get more
pixels or lose pixels, where do they come from? And
where do they go?

Speaker 1 (50:35):
Yeah? Great question, And that question assumes that they have
to come from somewhere, right you imagining like things like
energy in the universe are concerned. Right, you can't just
like pop new pixels out of nothing. But you know,
we don't actually know that. We don't know that energy
has to be conserved in the universe. We know that,
for example, when the universe expands, photons get red shifted,

(50:56):
they get stretched to longer wavelengths. That means they lose energy.
Where's that energy go? Nowhere? It doesn't have to go anywhere,
because maybe energy itself is not conserved in the universe.
So these are great questions because it might be that
they are the wrong questions, and the contradictions that come
up when we ask them lead us to asking the
right questions, which we don't know what those questions are yet.

(51:17):
But it's sort of like, you know, knowing the answer
is forty two and then going back and realizing, hmm,
maybe we asked the wrong question, or maybe we're thinking
about this whole thing wrong, you know. I think the
takeaway message for listeners is like, what is space? Well,
we don't know. We have two really nice descriptions of
what space might be, both of which work in different scenarios,
but both of which raise a lot of questions and

(51:38):
they don't agree with each other, and so we really
just don't know what space is. Even though we've made
a lot of progress and we can build iPhones and
launch rockets to Mars and all sorts of stuff. We
can move through space, we can manipulate space, doesn't mean
we yet know what it is, and it might be
a century or a thousand years before we really figure
it out.

Speaker 2 (51:57):
Well, that's exciting. I'm going to try to convince my
daughter to become a physicist. She's been wearing her Sern
outfits in her Stern hard hat since visiting CERN, so
maybe she's on the path.

Speaker 1 (52:07):
I think about space the way I think about like
a photon. People are often told, like a photon is
a particle. No, it's a wave. Or sometimes it's a particle,
sometimes it's a wave. The way I think about it
is like a photon. It's neither a particle or a wave.
Sometimes it's particle like, sometimes it's a wave like. It's
something else we haven't yet figured out. And the same
is true of space. We can describe space sometimes using
general relativity, we can describe it sometimes using quantum mechanics.

(52:30):
But space is probably something else. We've never even imagined,
something beyond yet our current thinking that maybe one of
our listeners is smart enough to.

Speaker 2 (52:38):
Figure out that would be awesome.

Speaker 1 (52:40):
All right, Well, thanks for going on this journey with
us into the philosophical underpinnings of physics. I hope I've
convinced you that physics is a way to think about
these big, deep questions without getting lost in the meaning
of the words, because it lets us be mathematical to
try to be precise, and then to ask philosophical questions
about those mathematical models, be like, what does it mean
that I can calculate this, but I can't measure that?

(53:02):
What does it tell us about the nature of the universe?
Even when those answers are or we really.

Speaker 2 (53:06):
Just have no clue, my brain today hurt in a
good way. I really enjoyed thinking about this today. It
was nice to have us someone to ask silly questions
to well.

Speaker 1 (53:16):
Thank you for all the silly and wonderful questions, and
thanks everybody else out there for thinking about the nature
of the universe. If you have questions about how things work,
don't be shy. Write to us if you have questions
at Daniel and Kelly dot org.

Speaker 2 (53:34):
Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We
would love to hear from you.

Speaker 1 (53:40):
We really would. We want to know what questions you
have about this extraordinary Universe.

Speaker 2 (53:46):
You want to know your thoughts on recent shows, suggestions
for future shows. If you contact us, we will get
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Speaker 1 (53:52):
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Speaker 2 (53:58):
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and K Universe.

Speaker 1 (54:08):
Don't be shy write to us