January 14, 2020 • 51 mins
Learn about cosmic inflation with Daniel and Jorge
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Speaker 1 (00:08):
Hey, Daniel, did you have a good holiday break? Oh?
I did, but you know, as usual, I ate too much.
You mean you ate cosmically too much? Yeah, I totally
overdid it. I'm like on the verge of becoming a
black hole myself. Would you say your waistline is inflating,
I'd say a few more bites and I'd be risking
(00:30):
becoming my own personal big bang big Daniel. I'm talking
dark matter here people. Oh no, let's cut to the
theme song. Cut to the theme song. Hi am or
(00:58):
handmade cartoonist and the creator of PhD comics. Hi, I'm Daniel,
I'm a particle physicist, and I am actually full of
dark matter. Welcome to our podcast, Daniel and Jorge Explain
the Universe, a production of I Heart Radio in which
we examine all things fascinating and amazing and bonkers about
our universe and explain them to you in a way
(01:19):
that you can actually understand. So it's a new decade here,
and so, Daniel, what do we have to look forward
to in physics? What do we have to look forward
to in physics? Wow? So much? There are all sorts
of new exciting telescopes coming online that will let us
see further and further into the ancient past. The Large
Hadron Collider is going to keep running and maybe discover
(01:40):
some crazy new particles. But you know the best thing
about looking forward in physics is that we have no
idea what we're going to discover. There are always surprises
out there waiting for us. There are surprises everywhere. Yeah,
that's awesome. Yeah there might be Hey, a new kind
of plantain or a strawberry flavored banana discovered by scientists somewhere.
You never know science. It's what's for dinner, and so
(02:04):
there's a lot of good stuff to look forward to.
I look forward to in looking back and thinking, Man,
those folks in had no idea what was coming. Interesting.
You look forward to the future so you can laugh
at the past. Yeah, it's a wonderful feeling to think,
look at what we know about the universe, and look
at how the people before us, including ourselves ten years ago,
(02:27):
really had no clue what was coming. And that's exciting
to me because it makes me enthusiastic about the next
ten years. You know, the mind blowing discoveries that physics
and the rest of science will reveal. Man, you're making
me feel bad about humans. They were so clueless, oh man,
with their like new Facebook craze and they didn't even
(02:47):
have TikTok or Instagram. No, but we learned a lot
about the universe in the twenty tens. You know, we
saw a whole bunch of new exo planets and discovered
the Higgs boson, and you are there really some pretty
big shifts that our understanding of the universe in the
last ten years. And since science is just accelerating exponentially,
then I look forward to even more mind blowing stuff
(03:10):
in the decade to come. Yeah, and technically we have
more universe now than we had in Right, the universe
is constantly expanding and getting bigger. There's new space being created,
so we have also that to look forward to. Right
in the future, there there will be even more space.
That's right, in the future, you will occupy a smaller
fraction of the universe because the universe is inflating. Oh no, wait,
(03:35):
so you're saying that the people in were more significant
than we are. Well, you know, what's the fraction of
infinity is still zero so relatively speaking. But you know,
I had a listener right in and make a really
fascinating point about the expansion of the universe that I
had never thought of before. Yeah, And they said, well,
what about in time travel books, if you go back
(03:57):
in time, then doesn't your body occupy a smaller space
in the universe back then than it does now? And
how do you account for that? And it's true, you know,
the space that you occupied twenty years ago has expanded
to a larger space, and so somehow you have to
factor that into your time travel novel. WHOA like if
(04:18):
you if you send your consciousness back, it has to
somehow fit into a smaller package or something. Yeah, it
has to shrink exactly. You gotta squeeze your way back
into the universe from ten years ago or twenty years ago.
On today's episode, we are going to not look forward
in time, but we're going to try to look backwards
in time almost as much as you can look backwards. Right,
(04:40):
that's right. We're gonna try to rewind all the way
back to the very beginning. Because I've noticed that in
conversations with listeners and just with folks around campus, that
there's still a lot of misunderstandings about the very beginning
of the universe. Right, because right now we have a
lot of space, there's a lot of universe, but at
some point in the past there was very little of
(05:00):
the universe. I don't know. I mean, I think right
now the universe is pretty dilute, but in the past,
the universe was more dense. It could be that the
universe has been infinite since its conception. So in that sense,
it doesn't really make sense to talk about having less universe.
It's just more compact, right, A denser infinity, yes, a
denser infinity exactly, versus a water down infinity, which you know,
(05:26):
it just doesn't taste as good. That's right. But I
think a lot of people when you talk about the
beginning of the universe and the Big Bang, they have
sort of an old idea in their head of what
the Big Bang was like this just this big explosion
from a singularity, and that's not really the modern view. Wait,
you're saying the name big bang doesn't actually describe the
Big Bang. I think it was pretty big and it
(05:48):
might have been a bang, so you know, from that
point of view. But I think the ideas in people's
heads need updating. I see, it's it's a kind of
big bang, yes, exactly. Big Bang and compass is like
a whole spectrum of ideas and physics has moved on,
while popular conception is sort of stuck in the eighties version, right,
And so this is a question that you said to me.
(06:11):
A lot of listeners asked wrote in to ask about
a lot of people are wondering and asking us to
explain what this idea is. Yeah, and so, as usually,
we want to cater to our listeners. We want to
answer the questions that are in your minds, and we
want to bring you to the forefront of science. We
want you to understand what scientists out there, who are
experts in this field, who know the most that any
(06:32):
human is ever known about the beginning of the universe,
what they are thinking about. We want to explain it
to you in a way that makes sense. So that's
our goal. So today on the episode, we'll be asking
the question, what is cosmic inflation? Inflation? Inflation? That's right,
(06:54):
it's not controlled by the Federal Reserve. It's not the
reason why your bank account is emptying. Wait, you mean
cosmic interest rate? Don't don't make a difference here. No,
we can't borrow money from the other universe. Orything can
my cosmic debt somehow bring it down? That's your karmic debt, actually,
and there's nothing you can do about that. Then do
(07:15):
good things for people, like explain the universe to them.
I think that's definitely a positive on the karmic debt,
right right, But today we're talking about cosmic inflation, and
that kind of sounds simple. It just means that the
cosmos is getting bigger or got bigger. But in this case,
scientists use this phrase for something very specific, right, like
a very specific moment in time right after the Big Bang.
(07:41):
Sort Of, it's both a specific moment in time that's
after the Big Bang, it's also sort of our modern
view of what the Big Bang was, and and it's
also connects the like primordial inflation, these first moments when
the universe is expanding with the current inflation, and it
says maybe these things are connected. So it's sort of
(08:03):
like saying the Big Bang wasn't the moment of creation.
It happened just afterwards. And it's saying maybe the Big
Bang is still banging. We're still banging, yes, exactly, that's
how big this bang is. Well, it sounds like it's
it's pretty interesting and maybe there are a lot of
subtle ideas here, so we'll get into all of that.
But first, as usual, we were wondering how many people
(08:24):
out there heard of the phrase cosmic inflation and if
they knew what it was. That's right. And so since
it was winter break and you see, Irvine was closed,
I walked around coffee shops in Irvine and I asked
random strangers who were amenable to being interrogated about physics
topics while on their holiday break if they knew anything
(08:46):
about cosmic inflation. Here's what they had to say. Oh,
I feel like I've heard the term, but I do
not know what it means. Um, cosmic inflation is that
like the theory where everything in space is like constantly
moving away from itself, like there's an explosion and everything's
still expanding. Yeah, I have no idea. I think it
(09:08):
means that just like crowding together, maybe like everything's coming together,
but I don't know. The universe is expanding and getting
bigger with each but as time passes, so something that's
happening now or in the past, it's still happening from
the universe. That's something that's happening now or in the
(09:28):
beginning the universe, or it's always been happening. Yes, what
is it? That's essentially the basis of the big bank theory? Okay, Um,
when did it happen fourteen point three billion years ago?
We might have more more satellites of space, space stations
or something. I have no idea. I mean it sounds
like the expansion of space, cosmic inflation. No, alright, a
(09:51):
lot of knows I feel, not a lot of inflated
answers here. No, no, no, and confusion people thinking like
space is getting smaller or the Earth is getting more crowded.
That maybe they thought space was getting devalued. Maybe there's
the there's the negative flip side to it that surprised.
(10:13):
The market for space is sad oversaturated. So better spend
your space now before it's worth nothing. Better use it up. Better,
eat more so you can take up more space. That's
that's my New Year's resolution. Eat more dark matter, take
up more space, make more dark better. But there were
some some core ideas here. You know, people have heard
(10:36):
of some connection to the Big Bang or some ideas
for things that happened in the early universe. So there's
definitely some nuggets there Yeah. A lot of people said
it related to the expansion of the universe, which is
I guess not a big stretch, right. Inflation and expansion
sort of sound the same. Yeah, And in fact I
think they're right. It is related to the expansion of
the universe as far as we know, which is not
(10:56):
very much, it turns out, you know, and this is
fascinating to me because it's something where we've made a
lot of progress in the last twenty years coming up
with new, crazy ideas about the universe, but something that
we're also still puzzled over, Like there are huge unanswered
questions about the Big Bang and cosmic inflation. There are
things that scientists are arguing about. You know, the guy
who came up with inflation, one of the architects of
(11:19):
the theory, Paul Steinhardt, is now the guy arguing against
the theory most Yeah, he's trying to deflate inflation, that's right.
He's trying to pop the bubble of his own creation.
So what's interesting I think is that, you know, if
you had asked what is the Big Bang, a lot
of people might have said, yes, it has had some
ideas about that. It's about the beginning of the universe,
(11:39):
but cosmic inflation, which is almost as important, doesn't have
the same kind of market recognition. Yeah, and that's what
we're going to try to correct today on the podcast.
We're gonna bring some panash to cosmic inflation. We're gonna
show people how big bang is sort of the old
busted theory and cosmic inflation is the new hotness. M
it's a new bang. It's the new bang. That's right
(12:01):
out with the old bang, in with it's climb. Are
you still banging the old way? Man? What's wrong with you? Try?
Are you physics bace banging? Yeah? I don't know what
advertisers are going to go for that. Somebody out there
has got a product that fits that. Alright, Diana, So
(12:23):
let's get into it. Let's get into this idea of
cosmic inflation. So, first of all, what is how would
you define inflation in a physics way? Basically, inflation is
the expansion of space. It's saying, let's take space and
stretch it. Let's make space bigger and it it's important
there to understand that it's not the moving of stuff
(12:44):
through space. It's really the stretching of space itself. So
are we stretching space or creating new space both both.
That is how you stretch spaces and you create new space.
I see, like there's more meters. It's not like the
meter got bigger, so it's just more meters of space. Yeah,
there are more meters of space. So stuff can be
further apart without moving through space. Right. It's like if
(13:08):
you take a ruler and you put a penny on
the one meter and on the two m and then
you stretch the ruler. The ruler itself is like may
out of elastic, and you stretch the rulers to make
it longer than the two pennies are further apart even
though they haven't moved relative to the ruler. That's expansion
of space. That's inflation of space. Right. But it's not
(13:30):
just that the ruler expanded. It's like the wood of
the ruler got bigger. You definitely add more to the ruler. Okay,
And so that's different than kind of the old idea
of how the Big Bank happened after the beginning of time. Yeah,
so let's dig into that in that way. Let's like
define what I think most people think the Big Bang
(13:50):
was and the sort of old idea of what the
universe was, and then let's contrast it with with sort
of what they should replace in their heads with. Okay,
so what's the old thing. The old thing, I think
is this idea that the universe started from a point
like a singularity and infinitely dense dot primordial atom, which
was a point in space. It was like somewhere and
(14:10):
it was infinitely dense. And remember, like nobody has in
the idea where this thing might have come from, what
could have created it. But that's sort of just like
swept under the rug, you know, the primordial rug, Like well,
you know, we don't know what came before, but let's
just start from there. Right, it was like a little tiny,
infinitely energetic package in sitting in space actually right like
it was. People think it was like a grenade sitting there.
(14:33):
It was really really small, exactly, And that's really key
insight there that space was already created. You already had space,
and you just had this dot in space. And then
it exploded and that stuff then flew out and it
spread out and slowly got more and more dilute, right
less dense like an explosion would, and spread out to
eventually form of the universe, and that's the stuff moving
(14:57):
through space. And that's what we call in science the
hot big Bang model. The hot big Bang is now
the old Big Bang. It's right, you know, it's like
your ex girlfriend and boyfriends. You still think they're hot,
but it's not really for you anymore. Man. So that's
probably the idea most people have in their heads when
you say big bang or creation in the universe. And
(15:17):
I think that's what I thought that the Big Bang was,
you know, way before, when I was in high school
or before I started hanging out with physicists, was that
the Big Bang is really just like a bang, Like
everything that we know about was in a small spot
and then it just exploded. And now all the stars
and galaxies and dust that was in that little bit
doot are now flying through space outwards. Yeah. And you know,
(15:38):
when you started hanging out with physicists, basically the moment
your universe was created. Everything else before that is like, oh,
waste of time. I see you. You created my universe, Daniel,
my universe started. There's nothing before I met you. There
you're supposed to go with you complete my universe. You're
saying you made my universe. Then that's even more romantic. Wow.
(16:02):
Well all right, yeah, I think on the back pedal
on that a little bit, But no, you're right, and
I think that's what most people think um as sort
of how the universe began, and you know, there's lots
of questions there um. But one big problem with that
conception is that it has a center, has a place
where the Big Bang happened. And if you were looking
at the explosion from any point of view, you would
(16:23):
see stuff sort of flying sideways, unless you happen to
be at the center, then everything would be flying in
a certain direction, right, and you could tell maybe where
the center of the universe was just by looking at
where all the things were, and you're flying away from
precisely and as a foreshadowing moment, that's not what we
see when we look out into space. Yeah. So at
(16:45):
some point a humanity physicist and scientists decided or started
to realize that this old model of the big band
was not the right one. Yeah. I mean it's a
good first draft. Like we're thinking about the universe, is
expanding what could have created it. You know, we don't
want to criticize those scientists, is being dumb or something
It's just sort of like science evolves, and this is
(17:06):
how it evolves. You have an idea, you compare it
to what you see. Doesn't quite work, so you improved
the idea. Right, They did a bang up job. It
was a big project. But but what I guess what
I mean is it at what point did we start
to sort of realize maybe this view was not the
correct one. Well, there's been a lot of problems with
(17:27):
the Big Bang basically since early on. You know when
ed when Hubble looked out into the universe and realized
it's like a hundred years ago that the universe was expanding,
That's sort of what gave birth to this concept of
a big Bang. He's the one who discovered that everything
was moving away from us, and everything was moving away
from us sort of the same speed in every direction
(17:47):
you looked. So this is an outstanding problem for the
Big Bang for a long time, and it wasn't until
this idea of inflation came along that it helped solve it.
So the Big Bang was not like totally accepted for
many many decades. And one problem what with it was,
you know, are we at the center? Why does it
look like we are at the center. Oh, I see.
(18:09):
He tried to figure out where the center of the
grenade was, and so he looked around and he found
that the center was us, which is weird, which was like,
too coincidental. It's too coincidental. Any time in science you
appear to be at the center of the universe, you
gotta wonder my biased or I'm just thinking about this wrong.
You know, you want to avoid coincidences. You want to
(18:31):
avoid things that are really unlikely, or especially things that
put humanity in the very important place in the cosmos.
Because we've made that mistake before, right, Like before we thought,
we like the Earth with decent was the center of
the Solar system. More than that, we thought it was
the center of the cosmos, right without everything was created
around the Earth, Yeah, right, right, And then it turns
(18:52):
out that the Sun, not even the Sun, is the
center of the universe. It's like just one star in
the rotating galaxy, which is part of something even bigger. Yeah,
And we like to think more democratically now. We like
to think that every point in space is equal, not
because they're voting or anything, but just that you know,
there should be no special locations because special locations require
(19:13):
special explanations. It just makes the most sense if everywhere
in space follows the same rules and is the same.
And that's why I like the Big Bang is a
point never really made sense to me, because then you
can always ask, like, well, why they're why did the
Big Bang start there and not like a meter over
or over there or a light year in the other direction,
why they're nowhere else? And so you avoid those questions
(19:34):
if you say, everywhere in the universe is the same.
All right, So that's the old bang, the old hot bang,
and now let's talk about the new hotter bang, I guess,
and in terms of trendiness um and why why we
think it happened and why is it still a mystery?
But first let's take a quick break. Okay, So Danny
(20:06):
telling me that the universe, the Big Bang is not
like a grenade that exploded that was full stuff and
then exploded, But the universe, the Big Bang is actually
something different where new space is being created and space
is being stretched. It's not an explosion, that's right. And
we still have to reconcile the fact that we think
the universe was more dense in the past than it
(20:27):
is today, and that makes you want to go to
the explosion explanation because you know, like, how else could
it happen? Right, because the grenade was denser before the explosion,
So you might be tempted to apply to our universe. Yeah,
So another approach and a better way to think about
it that it requires swallowing a really big idea, is
(20:48):
that the Big Bang essentially happened everywhere all at once.
That the universe wasn't created as a tiny singularity which
then exploded, but that the entire uni verse, an infinite
universe filled with an infinite amount of stuff, was created somehow,
we don't know how, in a very dense state, and
(21:09):
the Big Bang was the expansion of that state, the
stretching of space itself to make that stuff more dilute.
But that it was created everywhere and happened everywhere all
at once. So like that's an infinitely big bang. Okay,
So you're saying that the universe was has always been infinite.
It's not like it started as a point and became
exploited into infinity. You're saying that the universe was always infinite,
(21:33):
but that before it was like a dance and compact
infinite infinity but now it's more of a bigger and
more expanded infinity. Precisely, that's the idea. And of course
we don't know the size of the universe, and we
don't even know it's shape, but this is the idea.
It explains what we see, an infinite universe created infinitely
big and always filled with an infinite amount of stuff.
(21:55):
There's no edge to the matter, and there's no edge
to the universe, and just started out really hot and
dense and then stretched out right, But that's only one possibility, right,
that it's infinite. It could also be that the universe
is finite as far as we know. Right, it could
be right, but it at least has to be big
enough to fill our observable universe with a homogeneous stuff. Right.
(22:18):
If there is an edge to the stuff in the universe,
we don't see that, and so it has to be
really really big and and pretty uniform, at least in
our neighborhood. So it's possible that there's an edge to
the stuff in the universe. But it's sort of simpler somehow.
It's weird. It's weird. It's simpler to imagine an infinite
universe with infinite stuff because then you don't have to
(22:39):
explain the edges. Even though I can't explain how you
create an infinite universe with an infinite amount of stuff
in it either, well, nobody can explain it finite universe either. Right,
All this stuff defies explanation. But you know it's it's
like pushing the rock further up the hill. You don't
have to have the answer to every question. You just
have to ask have the answer to this question in
(23:00):
and then it gives you the next question. Like if
you say, let's assume the universe started infinitely large, filled
with an infinite amount of stuff, then what would have happened?
And you can show that that's consistent with what we
see so far, then you get to go back to
that other question, say, okay, let's roll up our sleeves
and figure out how it's possible to create an infinite universe. Um.
So that is that your approach to teaching as well, Daniel,
(23:22):
Just make it up as you go along, push all
the problems off until tomorrow. That's my approach to life.
Yes to my inbox as well. Yeah, and so the
idea is you create an infinite universe filled with an
infinite amount of stuff, but it's very hot and dense. Right,
it's like a huge singularity essentially. Okay, so I think
(23:44):
you're saying that the best way to think about the
big band it's not as like a little point that exploded,
but just as an infinity going from a really dense
infinity to a bigger infinity. Yeah, And that's what cosmic
inflation is, is taking that really dense um infinity and
stretching it out to a much more dilute infinity, because
(24:06):
that is what we see, that's what we have evidence for, right,
Like we see that the universe is really sparse and
I'm kind of empty now, and and we see that
everything used to be much much denser. Yeah, we need
to have inflation order to explain a bunch of stuff
that we see in the universe. And we can get
into that in a few minutes if you like. But
(24:26):
this explains why the universe looks the way that it does.
And without inflation, the universe doesn't really make sense. Like
if you just create the universe at this current density
and said it expanding now um ten billion years ago,
it wouldn't make sense. It doesn't explain what we see.
So you need to have this inflationary period in order
(24:47):
to get all the sort of the clumpiness and the
structure that we see in the temperature of stuff all correct. Okay,
So I think that's another key concept about inflation, which
is that it's not you know, the universe went from
a as infinity to a wider infinity, but it didn't
do it sort of evenly, right, like there were there
was a period of time where it was really expanding
(25:08):
really fast, and now it's expanding but not as fast.
And so what do you call inflation? Is it that
rapid expansion or is it the whole thing, or is
it that's still kind of undecided. That's a little bit fuzzy. Yeah,
I think if you talk to most cosmologists, they would
think about inflation as this very narrow period from tend
to the minus thirty six seconds after somehow the universe
(25:31):
was created, to tend to the minus thirty two seconds
after the universe was created, in which you had this
enormous expansion in the universe. It seems like a factor
of ten to the twenty six. That's what they would
think of as inflation. But I'd also like to think
about what, you know, what expansion is still happening, and
so maybe this is still really part of inflation. But
that was the most dramatic moment, and so I think,
(25:54):
you know, if you talk about inflation, that's the moment
that people are thinking about. Oh, I see, like we're
maybe it's just at the air party of the inflation,
but you could technically maybe still call it inflation night,
you know, like the Oscar's Night. That's right, is the
celebration after the super Bowl part of the super Bowl. Yeah,
you know, but it's nothing like yeah, like the tailgating
(26:14):
counts as part of the event, surely, yeah, exactly. The
tailgating created the whole thing. It's only because the fans
and you can even have a super Bowl. So there
you go. And one of my favorite things about inflation
is just sort of the mind boggling numbers. We're talking
about a really brief amount of time. Tend to the
minus thirty two seconds. It's like impossible to think about.
(26:35):
We talked recently on a podcast about how long particles live,
and I said that they last like ten to the
minus twenty three seconds, which seems impossibly short, but you know,
compared to tend to the minus thirty six. That's a
huge amount of time. The ideas that the universe went
from almost or actually infinitely dense and infinitely dense infinity
(26:58):
to a less infinite lead dance infinity in a matter
of seconds or fractions of fractions of a second. And
the expansion also is incredible. I mean ten to the
twenty six expansion is hard to get your mind around. Yeah,
it would take one meter and expanded to ten billion
(27:18):
light years. That's what happened at the beginning of time.
Is that a meter, Like suddenly a meter became ten
billion light years. Yeah, so the stuff that's in a
meter of space got stretched out and spread out over
ten billion light years in a matter of ten to
minus thirty two seconds. Yeah, one pachinko second or whatever
that unit is second. You know, if you're a cosmology is,
(27:41):
you get to make up whatever terms like because you're
this is uncharted territory in terms of scientific prefixes. Right,
I think I think you should claim it right now,
go online to chink that's the sound of me claiming
pachinko second and then gaining royalties from it. Then you
get to change seconds and the other thing to wrap
your mind around is that this is stuff that's happening
(28:01):
faster than the speed of light. You know, light can't
travel ten billion light years in ten to the minus
thirty two seconds, obviously, right, it would take ten billion
light years years to cross that distance. That's right, even
Han Solo would take twelve par Sex to get that far.
Which hand Solo though? That do you want here? The
old of course, the old one, the original? And I
(28:24):
want to get a shout out to all those fans
out there who wrote in and gave me an explanation
for why Han Solo quoted his Kessel run time in
par Sex because he found a shortcut. He wasn't using
it as a measure of time. He was referring to
the fact that he took a trip near some gravitational well,
which basically shortened his trip through space. So thank you
to all those fans who educated me on the physics
(28:45):
of Star Wars. Sounds like a whole episode we should do,
We should, certainly. But the idea here is that space
expanded faster than the speed of light. And so for
those of you physics afficionados who are thinking, what nothing
can go fast in the speed of light, you're night
that nothing can go faster than the speed of light
through space. But there's no limit to how fast space
(29:06):
can expand really no limit. You think you think space
can expand infinitely. Well, it made a pretty impressive expansion
in the first few moments of the universe. I mean,
I'm impressed we are not aware of a limit. I
mean there could be a limit, but you know, we
have evidence that this expansion happened in a mind boggling speed.
So things that used to be close by, they used
(29:27):
to be like a meter apart, where all of a sudden,
cosmically separated. They were in their own essentially observable universes.
You know, they could no longer see each other or
communicate with each other. That's a little sad. You know,
something tore them apart. Yeah, something tore them apart. And
that's actually an important clue as to why we think
(29:48):
inflation happened. And you know, this kind of expansion is
the same kind of expansion that we're talking about now
that we're talking about for dark energy. You know, people
in the interviews who said, huh, in space expanding now
is cosmic inflation talking about the current expansion of the universe. Maybe, right,
that there's no difference in the kind of expansion we're
(30:09):
seeing now that's driven by dark energy and the kind
of expansion that we're talking about for cosmic inflation. They're
the same expansion of space, right, And so so this was,
um what we that short, super crazy period happened near
the beginning of time, and it happened really fast, but
(30:29):
we don't know kind of why it happened, right, We
don't know what happened, and we don't know why it
stopped happening and sort of cool off for a while,
and then we don't know why it started happening a
little bit again five billion years ago when dark energy
sort of started taking over the universe. So yeah, we
don't understand the mechanism of it at all, right, but
(30:50):
it is pretty crazy, and maybe that is that kind
of where the idea of a big band came from,
Like from this crazy expansion. It's almost like an explosion
of space, right, you might call it or a bang
of space, or I think the original name big Bang
came as a sort of a joke trying to mock
somebody else's scientific theory, and that was thinking of the
universe is starting from a point and an explosion through space.
(31:13):
And people were like, what are you suggesting as a
theory of the whole universe? Something as whimsical as that
Big Bang? You know, I think probably said with a
snotty British accident, you know exactly what the sneer, right,
the curled lip, but it caught on it like the
Big mag like the Big mag. It was catchy precisely,
(31:34):
and you know it has its own special sauce. And
but it is sort of it is sort incredible that
I mean, it's sort of like if you were alive
back then, it would you would not survive that, right,
It would feel like an explosion. It would feel like
this crazy violent, uh you know, sudden thing that it
just happened suddenly. Yeah, if you're two ms high, then
(31:55):
you would suddenly become a twenty billion light year long
staying on the universe. Right, I feel like I'm a
staying in the universe now that yeah, but you're localized,
like infinitely stayed. Do you want to be a cosmic
smear in the universe? You know? And if you are
reading that time travel device, be careful don't go back
(32:16):
to far because you do not want to experience cosmic inflation, right,
but you know it's it's space and time are tied together.
So is this was time also moving slower or was
time moving? Is this all measured at the same time scale?
Oh yeah, that's a great question and a deep one,
and we don't really understand. But we're measuring these things
according to our time, so our proper time. You know
(32:40):
what when you have experienced in terms of time, if
you're living through that period, I don't know. And we
don't really have a mechanism for explaining how this happened.
We just sort of sort of describing that it did.
And so we don't understand, like, is this part of
general relativity, there's some term you can add to the
equations of general realtivity that create this expansion, or is
it some totally different than it is stretching space? And
(33:02):
so the answer to how it affects time depends a
little bit on the details of what's doing it, whether
it's part of general relativity or not. I think time
itself cost inflation about that? Is that a new idea?
Lame Craig lame credit to that high fi novel. That's right,
that is officially your idea. And look forward to seeing
(33:24):
the paper you're writing on it. All right, let's get
into why we think costmic inflation even happened in the
first place, and let's get into what is still a
big mystery about it. But first let's take another break. Okay,
(33:50):
Daniel Lid we're talking about cosmic inflation, which is the
new Big Bang? Should we just call it the big
inflationary Bang, the Biggest Bang? Maybe the bangie inflation. But
so that's a crazy idea, that this idea that the
universe went from an infinitely dense infinity to a less
(34:11):
infinitely dense infinity in less than ten to the twenty
six seconds. That's crazy. It's crazy. But you know, the
universe and reality are no stranger to absurdity, right, They
don't care what your definition of crazy is. Yeah, and
crazy stuff has happened. And that's one of my favorite
things about physics is learning that the universe is bonkers,
(34:32):
bonkers beyond our imagination sometimes so it stretches our concept
of reality completely. I guess my question to you is
why do scientists think that so much happen is such
a short amount of time? You know, basically, why do
we think that the Big Bang or the inflation happened
in the first place. Yeah, well, it solves some problems.
It explains some of the things that we see that
(34:54):
we can't otherwise resolve. I mean, you might come up
with another theory that explains what we see out there,
but it has to explain all the stuff that we
see and tie up all the loose ends. And one
of the things is what we mentioned earlier on is
that we seem to be at the center of the
universe and that doesn't make sense. And the the hot Big
Bang model we have a point that explodes out, but
(35:14):
it does explain what we see if the whole universe
was infinite and expanded out everywhere at once, because then
everywhere looks like it's at the center of the universe.
It's like you're in the middle of a loaf of
bread and all the reasons as it's baking, all the
reasons are moving away from you. That's true, no matter
where you are in this infinite loaf of bread. Yeah,
(35:34):
it's like being in a rubber sheet. Right when you
stretch it out wherever you stand, it looks like everything's
blooming away from you. Yeah, exactly, And and that's pretty compelling.
But then you might ask, all right, well, that just
requires that the universe is infinite and it is filled
with an infor amount of stuff. Why do you think
it had this crazy expansion? And part of that comes
with what we see out there in the universe is
(35:56):
that the universe is pretty smooth. I mean, there are
clumps and galaxies and solar systems. Will get into that
in a moment, but if you average out over it,
it looks pretty smooth. And most specifically, if you look
at this cosmic microwave background radiation, this light we've talked
about that comes from like three hundred thousand years after
the Big Bang, when the universe was a hot plasma.
(36:19):
We see that light and we use that light to
measure it's sort of the temperature of the universe by
the frequency of the light. And it's really really, really smooth.
Like it looks like the universe was basically the same
temperature everywhere. And that's weird. It's it's very even, right,
It's like it it all, it all looks the same
almost from every direction. Yeah, it looks like a smooth bath,
(36:43):
you know. It looks like the temperature varies by one
part in a hundred thousand or one part in ten
thousand from here to there to the other place. And
you might be thinking, well, what what's weird about that? Right, Well,
it's weird from the point of view that those things
are cosmically far upon heart. If you look at light
that's coming to us from one direction in the cosmic
(37:04):
micro background radiation, it's been traveling the whole history of
the universe, just got here. If you look from the
other direction, life coming from the other direction has also
been traveling the whole history universe and just got here.
So it's the first time they ever met, right from
different ends of the universe. Right, one of them came
from the left edge of the universe and the other
one came from the right edge of the right. Yeah, well,
(37:27):
even if there aren't any edges, they came from totally
separated spots, spots that have not had time to talk
to each other or communicate in any way since the
beginning of the universe. Right, that's weird. That's weird because
they're the same temperature, and the only way you can
get stuff to be the same temperature is to let
it mix, Right, Like if you put an ice cube
(37:48):
into hot water, then you have a cold spot in
your water, and you have to wait for things to mix,
for the temperature to get so even. And so it
looks like the universe had a chance to mix. It
looks like the temperature smoothed out. But how did that happen?
Because these things have never had a chance to talk
to each other before. Why what? What if it touch
(38:09):
is how the universe was before? Yeah, it could be.
You know, a lot of these problems are sort of aesthetic.
You're like, well, I don't really get it. I don't
like that assumption. And so you could say, well, the
universe were just created like perfectly smooth. Yeah, just came
off the factory floor, nice and nice and toasty. Yeah,
(38:29):
nice and toasty. It's not exactly smooth. We see little
clumps in there, and the distribution of those clumps is
another thing that's explained by inflation. But you're right, this,
you know, by itself, this smoothness problem is not completely bulletproof. Right.
You could say, maybe the universe was just created almost
perfectly smooth, like maybe when photons are creative at the beginning,
(38:53):
they all have the same temperature. There would be another
way to explain it. There would be another way to
explain it. But the explanation that comes from inflation and
is that these things did once have a chance to mix.
That you know, before inflation, these photons, which were ten
billion light years apart, were only a meter apart. And
so there's a lot of time in this early plasma
(39:13):
for stuff to slash around and for things to get
smoothed out and for the universe to get to an
even temperature before things got inflated. Right, And so I
think I remember this that the the the way that
this explains it. It is that you need this kind
of rapid and violent expansion of space to basically take
(39:33):
the left edge photon and the right edge photon far
enough apart where it makes sense now. Yeah, so these
two have had to been inside the same sort of
cosmic horizon before, and now they're outside the cosmic horizon.
Cosmic horizon is something that is so far away that
(39:54):
you have not seen it because light from it has
never reached you in the history of the universe. Right,
there's a no way they could have talked before, And
yet it seems like they had have talked before. And
the expansion of space faster than the speed of light
is the thing that can do that. It can take
things that were inside the same cosmic horizon, right, that
are close enough to interact and talk to each other,
(40:15):
and smooth them become the same temperature, and push them
apart into their own separate cosmic horizons so that they
can no longer interact. And so that's what we think
we see now is that light from this from two
directions in the universe is now the same temperature, even
though without cosmic inflation, we don't think that they could
ever have met, right, It's like it's like a crazy
(40:36):
thing you've see in the universe that can only be
explained apparently by this crazy idea of inflation. Yeah, precisely.
That's one reason why we like inflation. It explains that.
And more specifically, the universe is not all the same temperature.
If you look at the cosmic microwave background radiation, this
light from the early universe, we said, it's like the
(40:58):
same too, within one in ten thousand, one in a
hundred thousand. Those wiggles are actually important. Those those deviations
from being exactly the same temperature are really important, and
we study those really carefully because those are the seeds
of the rest of the universe, right, that they're the
wrinkles that came from basically this giant stretching of the universe. Yeah,
(41:18):
those those wrinkles came from the giant stretching. And you
might wonder, like, all right, say the universe was created
perfectly smoothly, like you were saying earlier, Right, why couldn't
just come off the factory floor, like totally homogeneous. Well,
if you have a universe like that, then you never
get any sort of clumping. You don't get anything like
solar systems and hamsters and galaxies and stuff, because everything
(41:41):
is perfectly smooth and there's no place where things start
to clump together. To get any sort of clumping or structure,
you need something and that's not homogeneous, right, And so
you're saying, inflation is our only explanation for why the
universe is smooth and clumpy just the right amount that
we see it right now. That's right, because in physics
(42:02):
we have only one way to introduce random clumpiness, and
that's quantum mechanics. So the idea is the universe was
really really dense and perfectly smooth, and then quantum fluctuations
just like created a few particles here and a few
particles there. Now, normally, when that happens, and it's happening
all the time, it's not a big deal because there
are the quantum level so you don't see them. But
(42:24):
what if just when you're making those fluctuations, the universe
decides I'm gonna blow this up to ten billion light years?
Then all of a sudden, tiny little quantum fluctuations become
really big cosmic fluctuations, right, they become spread out over
the whole cosmos. Then they're big enough to seed gravity,
to get things moving, to clump stuff together. Right and
(42:46):
if so, so, if an inflation was not as dramatic,
then we wouldn't see those quantum fluctuations, right, because let's
say that inflation had actually taken longer than you wouldn't
you know, it wouldn't stretch those quantum fluctuations because things
would even out before you stretch out to the to
(43:07):
what we see now. Yeah, And that's why you need
to have inflation happened at the scale that had happened
like so dramatically and so quickly. You've got to catch
those quantum fluctuations with their pants down. Otherwise it doesn't
explain the universe were in. That's right, Their cosmic embarrassment
is the reason why we are here. Yeah, that's sort
of basically right, right, Like, it's like you needed to
(43:30):
catch the universe just the right time with this crazy
expansion like this photograph in order to explain what we
see now. Yeah, And we talked on the podcast recently
about another possibility, another different idea, which was cosmic strings.
People thought, maybe cosmic strings are the reason why we
see this sort of distribution of stuff in the universe,
but people look at them more carefully and it doesn't work.
(43:50):
You don't get this sort of the right kind of wiggles,
you don't get the right distribution of stuff here and
stuff there. But inflation gets it just right. Inflation says,
if you had that really dense plasma and then you
blew it up really quickly, you would expect to get
just the right density of stuff to form the kind
of structure that we see today, And there's no other
way to explain it in such fine detail that we know.
(44:13):
I mean, there are some other crazier ideas, but none
of them work as well as inflation, right, Yeah, Like,
if inflation at lasts it tended to the negative thirty
one seconds instead of tend to negative thirty two seconds,
then you and I wouldn't be here. Yeah, it would
be some other podcasts which would be not nearly as funny.
It would probably be over quicker. But there's a there's
(44:34):
some something else there. There's a real randomness right, Like
it tells you that the structure to universe, Like why
does a galaxy here comes from some like electron fluctuating
out of the vacuum fourteen billion years ago, And if
it had fluctuated in a different direction, we'd have a
different galaxy somewhere else. Like those tiny little quantum rolls
of the dye determine the specific structure of our universe today.
(44:57):
It mind boggling to think about. And they're super sensitive, right,
and totally random, super sensitive and totally random. Yeah. Wow.
So we we are lucky to have the universe we
have right now, and you listeners are lucky to have us, frankly,
and we are lucky to have you. We are very
glad that you fluctuated into existence. We are all lucky
(45:18):
to have each other. I think is the new theme
for Okay cool. I feel like I really understand there's
a little bit more, you know. It's it's like this
idea of an infinite infinity going less dense is and
very quickly in order to explain what we have now.
So does that mean, Daniel, that we know everything about
inflation and what happened at the beginning of time? Or
(45:39):
are there still things we don't know? There's not an
infinite amount of stuff that we don't know about inflation,
infinitely amount of stuff we don't know about an infinite
lead dance infinity that gets less infinite. Yeah, as our
knowledge grows, it feels like our ignorance is also growing,
or like our knowledge of our ignorance is inflating as well,
you know. But that's the fun part about science. I
(46:00):
think the biggest mystery about inflation is like what caused it?
What made it happen? What could possibly expand space at
this crazy rate? Right? Like why didn't the universe just
stay the way it was before? Why did it have
to have this crazy expansion? Yeah, and why did the
expansion stop? And so as usual, we don't have any idea,
but we've already given it a name, and of course yeah,
(46:22):
we've we've called it the infloton not a joke. I
know it sounds like I'm making that up. But created
this field called the infloton field, which would have an
infloton particle, and the ideas that this field causes this
crazy expansion. It sort of just puts off the question like,
all right, well, what creates the inflotton field and what
(46:43):
controls it? Well, we have no idea, but it's just
sort of like a place to put our ideas. Interesting,
So we owe our existence and our universe to the
infloton Yeah, and the infloton The idea there is like
the universe is filled with this infloton field, which expands
space and sort of decays into ordinary matter. And that's
(47:04):
how you get ordinary matter. You have in photon field,
which then turns into corks and electrons and other kinds
of fields. Um. And we don't know like what would
cause that decay, Like that's when inflation stops, is when
it turns into normal matter. But we don't know like
why would it stopped and or why was it there
in the first place? Yeah, what was there first place?
And also did it stop? Like there might be it
(47:27):
might be that inflation sort of stopped in our part
of the universe, but it's still going on in other
parts of the universe. Could be the rest of the universe.
We're like in a little bubble, a pocket universe, and
the rest of the universe is still inflating. And imagine
how far If it got that far in ten of
the minus thirty two seconds, imagine what it could do
in fourteen billion years. Wow. So you're saying that maybe
(47:50):
we are even more insignificant than we had previously imagined. Yeah,
that's this idea. It's called eternal inflation. That the universe
is continuously inflating, and occasionally the inflation sort of decays
into normal matter, and then you get the kind of
universe we're familiar with, but that most of the universe
is just this massively expanding infloton field. Wait, are you saying, Daniel,
(48:11):
that the infloton works in mysterious ways? I'm saying exactly that,
mostly because we don't understand it at all, And so
can I start a new religion based on the infloton?
Are you the high priest of the inflation here? Yeah,
because I am both the high priest and the parishioner
of my church of the Inflaton. Yes, please donate to
the Church of the Inflaton. I think we just replaced
(48:35):
the spagetti master. Yeah, and so of course this feels
like a big place holder because it is we don't know,
and so it's just a way to say, if inflation happened,
what's a possible way it might have happened. And then
let's start to get to work on, you know, figuring
out how that theory has to look. Step one, give
it a science names and then figure it out. Step
(48:56):
to get ridiculed by Jorge. Step three, get to work alright. Cool,
It sounds like there's still lots of answers to be
found in this and these are important answers, right, I
mean they're they're about the beginning of the universe and
why are things the way they are? And are things
going to change in the future. And you know, I
think in ten years or in twenty years, people will
(49:18):
look back at these ideas and think, oh, my gosh,
how absurd. I can't believe they really believe that stuff.
Because we're going to learn things about inflation, and we're
going to learn things about the history of the universe
and its current expansion that are going to give us
better ideas, even crazier ideas that are going to be
even more correct. And so this is the perfect example
of how our knowledge of the universe is constantly expanding.
(49:40):
We look back and think, wow, how silly. Yeah, you
know they say twenties smart physicists are twenty thirties ignoratons.
That's right, Yeah, I have twenty twenty vision, which means
I look back at ten and think one a bunch
of ideas. Well, I can't wait to have visions. That's
(50:00):
what happens in our old age, right, we all get
reading to us is all right? Well, maybe we'll get
into these mysteries a little bit deeper in the future podcast,
but for now, thanks for joining us. We hope you
enjoyed that. We hope we inflated your mind and took
you on a tour of the early universe. Thank you
very much. Before you still have a question after listening
(50:26):
to all these explanations, please drop us a line. We'd
love to hear from you. You can find us on Facebook, Twitter,
and Instagram at Daniel and Jorge that's one word, or
email us at Feedback at Daniel and Jorge dot com.
Thanks for listening, and remember that Daniel and Jorge Explain
the Universe is a production of I heart Radio. For
more podcast from my heart Radio, visit the i heart
(50:49):
Radio app, Apple Podcasts, or wherever you listen to your
favorite shows.
Hey, Daniel, did you have a good holiday break? Oh?
I did, but you know, as usual, I ate too much.
You mean you ate cosmically too much? Yeah, I totally
overdid it. I'm like on the verge of becoming a
black hole myself. Would you say your waistline is inflating,
I'd say a few more bites and I'd be risking
(00:30):
becoming my own personal big bang big Daniel. I'm talking
dark matter here people. Oh no, let's cut to the
theme song. Cut to the theme song. Hi am or
(00:58):
handmade cartoonist and the creator of PhD comics. Hi, I'm Daniel,
I'm a particle physicist, and I am actually full of
dark matter. Welcome to our podcast, Daniel and Jorge Explain
the Universe, a production of I Heart Radio in which
we examine all things fascinating and amazing and bonkers about
our universe and explain them to you in a way
(01:19):
that you can actually understand. So it's a new decade here,
and so, Daniel, what do we have to look forward
to in physics? What do we have to look forward
to in physics? Wow? So much? There are all sorts
of new exciting telescopes coming online that will let us
see further and further into the ancient past. The Large
Hadron Collider is going to keep running and maybe discover
(01:40):
some crazy new particles. But you know the best thing
about looking forward in physics is that we have no
idea what we're going to discover. There are always surprises
out there waiting for us. There are surprises everywhere. Yeah,
that's awesome. Yeah there might be Hey, a new kind
of plantain or a strawberry flavored banana discovered by scientists somewhere.
You never know science. It's what's for dinner, and so
(02:04):
there's a lot of good stuff to look forward to.
I look forward to in looking back and thinking, Man,
those folks in had no idea what was coming. Interesting.
You look forward to the future so you can laugh
at the past. Yeah, it's a wonderful feeling to think,
look at what we know about the universe, and look
at how the people before us, including ourselves ten years ago,
(02:27):
really had no clue what was coming. And that's exciting
to me because it makes me enthusiastic about the next
ten years. You know, the mind blowing discoveries that physics
and the rest of science will reveal. Man, you're making
me feel bad about humans. They were so clueless, oh man,
with their like new Facebook craze and they didn't even
(02:47):
have TikTok or Instagram. No, but we learned a lot
about the universe in the twenty tens. You know, we
saw a whole bunch of new exo planets and discovered
the Higgs boson, and you are there really some pretty
big shifts that our understanding of the universe in the
last ten years. And since science is just accelerating exponentially,
then I look forward to even more mind blowing stuff
(03:10):
in the decade to come. Yeah, and technically we have
more universe now than we had in Right, the universe
is constantly expanding and getting bigger. There's new space being created,
so we have also that to look forward to. Right
in the future, there there will be even more space.
That's right, in the future, you will occupy a smaller
fraction of the universe because the universe is inflating. Oh no, wait,
(03:35):
so you're saying that the people in were more significant
than we are. Well, you know, what's the fraction of
infinity is still zero so relatively speaking. But you know,
I had a listener right in and make a really
fascinating point about the expansion of the universe that I
had never thought of before. Yeah, And they said, well,
what about in time travel books, if you go back
(03:57):
in time, then doesn't your body occupy a smaller space
in the universe back then than it does now? And
how do you account for that? And it's true, you know,
the space that you occupied twenty years ago has expanded
to a larger space, and so somehow you have to
factor that into your time travel novel. WHOA like if
(04:18):
you if you send your consciousness back, it has to
somehow fit into a smaller package or something. Yeah, it
has to shrink exactly. You gotta squeeze your way back
into the universe from ten years ago or twenty years ago.
On today's episode, we are going to not look forward
in time, but we're going to try to look backwards
in time almost as much as you can look backwards. Right,
(04:40):
that's right. We're gonna try to rewind all the way
back to the very beginning. Because I've noticed that in
conversations with listeners and just with folks around campus, that
there's still a lot of misunderstandings about the very beginning
of the universe. Right, because right now we have a
lot of space, there's a lot of universe, but at
some point in the past there was very little of
(05:00):
the universe. I don't know. I mean, I think right
now the universe is pretty dilute, but in the past,
the universe was more dense. It could be that the
universe has been infinite since its conception. So in that sense,
it doesn't really make sense to talk about having less universe.
It's just more compact, right, A denser infinity, yes, a
denser infinity exactly, versus a water down infinity, which you know,
(05:26):
it just doesn't taste as good. That's right. But I
think a lot of people when you talk about the
beginning of the universe and the Big Bang, they have
sort of an old idea in their head of what
the Big Bang was like this just this big explosion
from a singularity, and that's not really the modern view. Wait,
you're saying the name big bang doesn't actually describe the
Big Bang. I think it was pretty big and it
(05:48):
might have been a bang, so you know, from that
point of view. But I think the ideas in people's
heads need updating. I see, it's it's a kind of
big bang, yes, exactly. Big Bang and compass is like
a whole spectrum of ideas and physics has moved on,
while popular conception is sort of stuck in the eighties version, right,
And so this is a question that you said to me.
(06:11):
A lot of listeners asked wrote in to ask about
a lot of people are wondering and asking us to
explain what this idea is. Yeah, and so, as usually,
we want to cater to our listeners. We want to
answer the questions that are in your minds, and we
want to bring you to the forefront of science. We
want you to understand what scientists out there, who are
experts in this field, who know the most that any
(06:32):
human is ever known about the beginning of the universe,
what they are thinking about. We want to explain it
to you in a way that makes sense. So that's
our goal. So today on the episode, we'll be asking
the question, what is cosmic inflation? Inflation? Inflation? That's right,
(06:54):
it's not controlled by the Federal Reserve. It's not the
reason why your bank account is emptying. Wait, you mean
cosmic interest rate? Don't don't make a difference here. No,
we can't borrow money from the other universe. Orything can
my cosmic debt somehow bring it down? That's your karmic debt, actually,
and there's nothing you can do about that. Then do
(07:15):
good things for people, like explain the universe to them.
I think that's definitely a positive on the karmic debt,
right right, But today we're talking about cosmic inflation, and
that kind of sounds simple. It just means that the
cosmos is getting bigger or got bigger. But in this case,
scientists use this phrase for something very specific, right, like
a very specific moment in time right after the Big Bang.
(07:41):
Sort Of, it's both a specific moment in time that's
after the Big Bang, it's also sort of our modern
view of what the Big Bang was, and and it's
also connects the like primordial inflation, these first moments when
the universe is expanding with the current inflation, and it
says maybe these things are connected. So it's sort of
(08:03):
like saying the Big Bang wasn't the moment of creation.
It happened just afterwards. And it's saying maybe the Big
Bang is still banging. We're still banging, yes, exactly, that's
how big this bang is. Well, it sounds like it's
it's pretty interesting and maybe there are a lot of
subtle ideas here, so we'll get into all of that.
But first, as usual, we were wondering how many people
(08:24):
out there heard of the phrase cosmic inflation and if
they knew what it was. That's right. And so since
it was winter break and you see, Irvine was closed,
I walked around coffee shops in Irvine and I asked
random strangers who were amenable to being interrogated about physics
topics while on their holiday break if they knew anything
(08:46):
about cosmic inflation. Here's what they had to say. Oh,
I feel like I've heard the term, but I do
not know what it means. Um, cosmic inflation is that
like the theory where everything in space is like constantly
moving away from itself, like there's an explosion and everything's
still expanding. Yeah, I have no idea. I think it
(09:08):
means that just like crowding together, maybe like everything's coming together,
but I don't know. The universe is expanding and getting
bigger with each but as time passes, so something that's
happening now or in the past, it's still happening from
the universe. That's something that's happening now or in the
(09:28):
beginning the universe, or it's always been happening. Yes, what
is it? That's essentially the basis of the big bank theory? Okay, Um,
when did it happen fourteen point three billion years ago?
We might have more more satellites of space, space stations
or something. I have no idea. I mean it sounds
like the expansion of space, cosmic inflation. No, alright, a
(09:51):
lot of knows I feel, not a lot of inflated
answers here. No, no, no, and confusion people thinking like
space is getting smaller or the Earth is getting more crowded.
That maybe they thought space was getting devalued. Maybe there's
the there's the negative flip side to it that surprised.
(10:13):
The market for space is sad oversaturated. So better spend
your space now before it's worth nothing. Better use it up. Better,
eat more so you can take up more space. That's
that's my New Year's resolution. Eat more dark matter, take
up more space, make more dark better. But there were
some some core ideas here. You know, people have heard
(10:36):
of some connection to the Big Bang or some ideas
for things that happened in the early universe. So there's
definitely some nuggets there Yeah. A lot of people said
it related to the expansion of the universe, which is
I guess not a big stretch, right. Inflation and expansion
sort of sound the same. Yeah, And in fact I
think they're right. It is related to the expansion of
the universe as far as we know, which is not
(10:56):
very much, it turns out, you know, and this is
fascinating to me because it's something where we've made a
lot of progress in the last twenty years coming up
with new, crazy ideas about the universe, but something that
we're also still puzzled over, Like there are huge unanswered
questions about the Big Bang and cosmic inflation. There are
things that scientists are arguing about. You know, the guy
who came up with inflation, one of the architects of
(11:19):
the theory, Paul Steinhardt, is now the guy arguing against
the theory most Yeah, he's trying to deflate inflation, that's right.
He's trying to pop the bubble of his own creation.
So what's interesting I think is that, you know, if
you had asked what is the Big Bang, a lot
of people might have said, yes, it has had some
ideas about that. It's about the beginning of the universe,
(11:39):
but cosmic inflation, which is almost as important, doesn't have
the same kind of market recognition. Yeah, and that's what
we're going to try to correct today on the podcast.
We're gonna bring some panash to cosmic inflation. We're gonna
show people how big bang is sort of the old
busted theory and cosmic inflation is the new hotness. M
it's a new bang. It's the new bang. That's right
(12:01):
out with the old bang, in with it's climb. Are
you still banging the old way? Man? What's wrong with you? Try?
Are you physics bace banging? Yeah? I don't know what
advertisers are going to go for that. Somebody out there
has got a product that fits that. Alright, Diana, So
(12:23):
let's get into it. Let's get into this idea of
cosmic inflation. So, first of all, what is how would
you define inflation in a physics way? Basically, inflation is
the expansion of space. It's saying, let's take space and
stretch it. Let's make space bigger and it it's important
there to understand that it's not the moving of stuff
(12:44):
through space. It's really the stretching of space itself. So
are we stretching space or creating new space both both.
That is how you stretch spaces and you create new space.
I see, like there's more meters. It's not like the
meter got bigger, so it's just more meters of space. Yeah,
there are more meters of space. So stuff can be
further apart without moving through space. Right. It's like if
(13:08):
you take a ruler and you put a penny on
the one meter and on the two m and then
you stretch the ruler. The ruler itself is like may
out of elastic, and you stretch the rulers to make
it longer than the two pennies are further apart even
though they haven't moved relative to the ruler. That's expansion
of space. That's inflation of space. Right. But it's not
(13:30):
just that the ruler expanded. It's like the wood of
the ruler got bigger. You definitely add more to the ruler. Okay,
And so that's different than kind of the old idea
of how the Big Bank happened after the beginning of time. Yeah,
so let's dig into that in that way. Let's like
define what I think most people think the Big Bang
(13:50):
was and the sort of old idea of what the
universe was, and then let's contrast it with with sort
of what they should replace in their heads with. Okay,
so what's the old thing. The old thing, I think
is this idea that the universe started from a point
like a singularity and infinitely dense dot primordial atom, which
was a point in space. It was like somewhere and
(14:10):
it was infinitely dense. And remember, like nobody has in
the idea where this thing might have come from, what
could have created it. But that's sort of just like
swept under the rug, you know, the primordial rug, Like well,
you know, we don't know what came before, but let's
just start from there. Right, it was like a little tiny,
infinitely energetic package in sitting in space actually right like
it was. People think it was like a grenade sitting there.
(14:33):
It was really really small, exactly, And that's really key
insight there that space was already created. You already had space,
and you just had this dot in space. And then
it exploded and that stuff then flew out and it
spread out and slowly got more and more dilute, right
less dense like an explosion would, and spread out to
eventually form of the universe, and that's the stuff moving
(14:57):
through space. And that's what we call in science the
hot big Bang model. The hot big Bang is now
the old Big Bang. It's right, you know, it's like
your ex girlfriend and boyfriends. You still think they're hot,
but it's not really for you anymore. Man. So that's
probably the idea most people have in their heads when
you say big bang or creation in the universe. And
(15:17):
I think that's what I thought that the Big Bang was,
you know, way before, when I was in high school
or before I started hanging out with physicists, was that
the Big Bang is really just like a bang, Like
everything that we know about was in a small spot
and then it just exploded. And now all the stars
and galaxies and dust that was in that little bit
doot are now flying through space outwards. Yeah. And you know,
(15:38):
when you started hanging out with physicists, basically the moment
your universe was created. Everything else before that is like, oh,
waste of time. I see you. You created my universe, Daniel,
my universe started. There's nothing before I met you. There
you're supposed to go with you complete my universe. You're
saying you made my universe. Then that's even more romantic. Wow.
(16:02):
Well all right, yeah, I think on the back pedal
on that a little bit, But no, you're right, and
I think that's what most people think um as sort
of how the universe began, and you know, there's lots
of questions there um. But one big problem with that
conception is that it has a center, has a place
where the Big Bang happened. And if you were looking
at the explosion from any point of view, you would
(16:23):
see stuff sort of flying sideways, unless you happen to
be at the center, then everything would be flying in
a certain direction, right, and you could tell maybe where
the center of the universe was just by looking at
where all the things were, and you're flying away from
precisely and as a foreshadowing moment, that's not what we
see when we look out into space. Yeah. So at
(16:45):
some point a humanity physicist and scientists decided or started
to realize that this old model of the big band
was not the right one. Yeah. I mean it's a
good first draft. Like we're thinking about the universe, is
expanding what could have created it. You know, we don't
want to criticize those scientists, is being dumb or something
It's just sort of like science evolves, and this is
(17:06):
how it evolves. You have an idea, you compare it
to what you see. Doesn't quite work, so you improved
the idea. Right, They did a bang up job. It
was a big project. But but what I guess what
I mean is it at what point did we start
to sort of realize maybe this view was not the
correct one. Well, there's been a lot of problems with
(17:27):
the Big Bang basically since early on. You know when
ed when Hubble looked out into the universe and realized
it's like a hundred years ago that the universe was expanding,
That's sort of what gave birth to this concept of
a big Bang. He's the one who discovered that everything
was moving away from us, and everything was moving away
from us sort of the same speed in every direction
(17:47):
you looked. So this is an outstanding problem for the
Big Bang for a long time, and it wasn't until
this idea of inflation came along that it helped solve it.
So the Big Bang was not like totally accepted for
many many decades. And one problem what with it was,
you know, are we at the center? Why does it
look like we are at the center. Oh, I see.
(18:09):
He tried to figure out where the center of the
grenade was, and so he looked around and he found
that the center was us, which is weird, which was like,
too coincidental. It's too coincidental. Any time in science you
appear to be at the center of the universe, you
gotta wonder my biased or I'm just thinking about this wrong.
You know, you want to avoid coincidences. You want to
(18:31):
avoid things that are really unlikely, or especially things that
put humanity in the very important place in the cosmos.
Because we've made that mistake before, right, Like before we thought,
we like the Earth with decent was the center of
the Solar system. More than that, we thought it was
the center of the cosmos, right without everything was created
around the Earth, Yeah, right, right, And then it turns
(18:52):
out that the Sun, not even the Sun, is the
center of the universe. It's like just one star in
the rotating galaxy, which is part of something even bigger. Yeah,
And we like to think more democratically now. We like
to think that every point in space is equal, not
because they're voting or anything, but just that you know,
there should be no special locations because special locations require
(19:13):
special explanations. It just makes the most sense if everywhere
in space follows the same rules and is the same.
And that's why I like the Big Bang is a
point never really made sense to me, because then you
can always ask, like, well, why they're why did the
Big Bang start there and not like a meter over
or over there or a light year in the other direction,
why they're nowhere else? And so you avoid those questions
(19:34):
if you say, everywhere in the universe is the same.
All right, So that's the old bang, the old hot bang,
and now let's talk about the new hotter bang, I guess,
and in terms of trendiness um and why why we
think it happened and why is it still a mystery?
But first let's take a quick break. Okay, So Danny
(20:06):
telling me that the universe, the Big Bang is not
like a grenade that exploded that was full stuff and
then exploded, But the universe, the Big Bang is actually
something different where new space is being created and space
is being stretched. It's not an explosion, that's right. And
we still have to reconcile the fact that we think
the universe was more dense in the past than it
(20:27):
is today, and that makes you want to go to
the explosion explanation because you know, like, how else could
it happen? Right, because the grenade was denser before the explosion,
So you might be tempted to apply to our universe. Yeah,
So another approach and a better way to think about
it that it requires swallowing a really big idea, is
(20:48):
that the Big Bang essentially happened everywhere all at once.
That the universe wasn't created as a tiny singularity which
then exploded, but that the entire uni verse, an infinite
universe filled with an infinite amount of stuff, was created somehow,
we don't know how, in a very dense state, and
(21:09):
the Big Bang was the expansion of that state, the
stretching of space itself to make that stuff more dilute.
But that it was created everywhere and happened everywhere all
at once. So like that's an infinitely big bang. Okay,
So you're saying that the universe was has always been infinite.
It's not like it started as a point and became
exploited into infinity. You're saying that the universe was always infinite,
(21:33):
but that before it was like a dance and compact
infinite infinity but now it's more of a bigger and
more expanded infinity. Precisely, that's the idea. And of course
we don't know the size of the universe, and we
don't even know it's shape, but this is the idea.
It explains what we see, an infinite universe created infinitely
big and always filled with an infinite amount of stuff.
(21:55):
There's no edge to the matter, and there's no edge
to the universe, and just started out really hot and
dense and then stretched out right, But that's only one possibility, right,
that it's infinite. It could also be that the universe
is finite as far as we know. Right, it could
be right, but it at least has to be big
enough to fill our observable universe with a homogeneous stuff. Right.
(22:18):
If there is an edge to the stuff in the universe,
we don't see that, and so it has to be
really really big and and pretty uniform, at least in
our neighborhood. So it's possible that there's an edge to
the stuff in the universe. But it's sort of simpler somehow.
It's weird. It's weird. It's simpler to imagine an infinite
universe with infinite stuff because then you don't have to
(22:39):
explain the edges. Even though I can't explain how you
create an infinite universe with an infinite amount of stuff
in it either, well, nobody can explain it finite universe either. Right,
All this stuff defies explanation. But you know it's it's
like pushing the rock further up the hill. You don't
have to have the answer to every question. You just
have to ask have the answer to this question in
(23:00):
and then it gives you the next question. Like if
you say, let's assume the universe started infinitely large, filled
with an infinite amount of stuff, then what would have happened?
And you can show that that's consistent with what we
see so far, then you get to go back to
that other question, say, okay, let's roll up our sleeves
and figure out how it's possible to create an infinite universe. Um.
So that is that your approach to teaching as well, Daniel,
(23:22):
Just make it up as you go along, push all
the problems off until tomorrow. That's my approach to life.
Yes to my inbox as well. Yeah, and so the
idea is you create an infinite universe filled with an
infinite amount of stuff, but it's very hot and dense. Right,
it's like a huge singularity essentially. Okay, so I think
(23:44):
you're saying that the best way to think about the
big band it's not as like a little point that exploded,
but just as an infinity going from a really dense
infinity to a bigger infinity. Yeah, And that's what cosmic
inflation is, is taking that really dense um infinity and
stretching it out to a much more dilute infinity, because
(24:06):
that is what we see, that's what we have evidence for, right,
Like we see that the universe is really sparse and
I'm kind of empty now, and and we see that
everything used to be much much denser. Yeah, we need
to have inflation order to explain a bunch of stuff
that we see in the universe. And we can get
into that in a few minutes if you like. But
(24:26):
this explains why the universe looks the way that it does.
And without inflation, the universe doesn't really make sense. Like
if you just create the universe at this current density
and said it expanding now um ten billion years ago,
it wouldn't make sense. It doesn't explain what we see.
So you need to have this inflationary period in order
(24:47):
to get all the sort of the clumpiness and the
structure that we see in the temperature of stuff all correct. Okay,
So I think that's another key concept about inflation, which
is that it's not you know, the universe went from
a as infinity to a wider infinity, but it didn't
do it sort of evenly, right, like there were there
was a period of time where it was really expanding
(25:08):
really fast, and now it's expanding but not as fast.
And so what do you call inflation? Is it that
rapid expansion or is it the whole thing, or is
it that's still kind of undecided. That's a little bit fuzzy. Yeah,
I think if you talk to most cosmologists, they would
think about inflation as this very narrow period from tend
to the minus thirty six seconds after somehow the universe
(25:31):
was created, to tend to the minus thirty two seconds
after the universe was created, in which you had this
enormous expansion in the universe. It seems like a factor
of ten to the twenty six. That's what they would
think of as inflation. But I'd also like to think
about what, you know, what expansion is still happening, and
so maybe this is still really part of inflation. But
that was the most dramatic moment, and so I think,
(25:54):
you know, if you talk about inflation, that's the moment
that people are thinking about. Oh, I see, like we're
maybe it's just at the air party of the inflation,
but you could technically maybe still call it inflation night,
you know, like the Oscar's Night. That's right, is the
celebration after the super Bowl part of the super Bowl. Yeah,
you know, but it's nothing like yeah, like the tailgating
(26:14):
counts as part of the event, surely, yeah, exactly. The
tailgating created the whole thing. It's only because the fans
and you can even have a super Bowl. So there
you go. And one of my favorite things about inflation
is just sort of the mind boggling numbers. We're talking
about a really brief amount of time. Tend to the
minus thirty two seconds. It's like impossible to think about.
(26:35):
We talked recently on a podcast about how long particles live,
and I said that they last like ten to the
minus twenty three seconds, which seems impossibly short, but you know,
compared to tend to the minus thirty six. That's a
huge amount of time. The ideas that the universe went
from almost or actually infinitely dense and infinitely dense infinity
(26:58):
to a less infinite lead dance infinity in a matter
of seconds or fractions of fractions of a second. And
the expansion also is incredible. I mean ten to the
twenty six expansion is hard to get your mind around. Yeah,
it would take one meter and expanded to ten billion
(27:18):
light years. That's what happened at the beginning of time.
Is that a meter, Like suddenly a meter became ten
billion light years. Yeah, so the stuff that's in a
meter of space got stretched out and spread out over
ten billion light years in a matter of ten to
minus thirty two seconds. Yeah, one pachinko second or whatever
that unit is second. You know, if you're a cosmology is,
(27:41):
you get to make up whatever terms like because you're
this is uncharted territory in terms of scientific prefixes. Right,
I think I think you should claim it right now,
go online to chink that's the sound of me claiming
pachinko second and then gaining royalties from it. Then you
get to change seconds and the other thing to wrap
your mind around is that this is stuff that's happening
(28:01):
faster than the speed of light. You know, light can't
travel ten billion light years in ten to the minus
thirty two seconds, obviously, right, it would take ten billion
light years years to cross that distance. That's right, even
Han Solo would take twelve par Sex to get that far.
Which hand Solo though? That do you want here? The
old of course, the old one, the original? And I
(28:24):
want to get a shout out to all those fans
out there who wrote in and gave me an explanation
for why Han Solo quoted his Kessel run time in
par Sex because he found a shortcut. He wasn't using
it as a measure of time. He was referring to
the fact that he took a trip near some gravitational well,
which basically shortened his trip through space. So thank you
to all those fans who educated me on the physics
(28:45):
of Star Wars. Sounds like a whole episode we should do,
We should, certainly. But the idea here is that space
expanded faster than the speed of light. And so for
those of you physics afficionados who are thinking, what nothing
can go fast in the speed of light, you're night
that nothing can go faster than the speed of light
through space. But there's no limit to how fast space
(29:06):
can expand really no limit. You think you think space
can expand infinitely. Well, it made a pretty impressive expansion
in the first few moments of the universe. I mean,
I'm impressed we are not aware of a limit. I
mean there could be a limit, but you know, we
have evidence that this expansion happened in a mind boggling speed.
So things that used to be close by, they used
(29:27):
to be like a meter apart, where all of a sudden,
cosmically separated. They were in their own essentially observable universes.
You know, they could no longer see each other or
communicate with each other. That's a little sad. You know,
something tore them apart. Yeah, something tore them apart. And
that's actually an important clue as to why we think
(29:48):
inflation happened. And you know, this kind of expansion is
the same kind of expansion that we're talking about now
that we're talking about for dark energy. You know, people
in the interviews who said, huh, in space expanding now
is cosmic inflation talking about the current expansion of the universe. Maybe, right,
that there's no difference in the kind of expansion we're
(30:09):
seeing now that's driven by dark energy and the kind
of expansion that we're talking about for cosmic inflation. They're
the same expansion of space, right, And so so this was,
um what we that short, super crazy period happened near
the beginning of time, and it happened really fast, but
(30:29):
we don't know kind of why it happened, right, We
don't know what happened, and we don't know why it
stopped happening and sort of cool off for a while,
and then we don't know why it started happening a
little bit again five billion years ago when dark energy
sort of started taking over the universe. So yeah, we
don't understand the mechanism of it at all, right, but
(30:50):
it is pretty crazy, and maybe that is that kind
of where the idea of a big band came from,
Like from this crazy expansion. It's almost like an explosion
of space, right, you might call it or a bang
of space, or I think the original name big Bang
came as a sort of a joke trying to mock
somebody else's scientific theory, and that was thinking of the
universe is starting from a point and an explosion through space.
(31:13):
And people were like, what are you suggesting as a
theory of the whole universe? Something as whimsical as that
Big Bang? You know, I think probably said with a
snotty British accident, you know exactly what the sneer, right,
the curled lip, but it caught on it like the
Big mag like the Big mag. It was catchy precisely,
(31:34):
and you know it has its own special sauce. And
but it is sort of it is sort incredible that
I mean, it's sort of like if you were alive
back then, it would you would not survive that, right,
It would feel like an explosion. It would feel like
this crazy violent, uh you know, sudden thing that it
just happened suddenly. Yeah, if you're two ms high, then
(31:55):
you would suddenly become a twenty billion light year long
staying on the universe. Right, I feel like I'm a
staying in the universe now that yeah, but you're localized,
like infinitely stayed. Do you want to be a cosmic
smear in the universe? You know? And if you are
reading that time travel device, be careful don't go back
(32:16):
to far because you do not want to experience cosmic inflation, right,
but you know it's it's space and time are tied together.
So is this was time also moving slower or was
time moving? Is this all measured at the same time scale?
Oh yeah, that's a great question and a deep one,
and we don't really understand. But we're measuring these things
according to our time, so our proper time. You know
(32:40):
what when you have experienced in terms of time, if
you're living through that period, I don't know. And we
don't really have a mechanism for explaining how this happened.
We just sort of sort of describing that it did.
And so we don't understand, like, is this part of
general relativity, there's some term you can add to the
equations of general realtivity that create this expansion, or is
it some totally different than it is stretching space? And
(33:02):
so the answer to how it affects time depends a
little bit on the details of what's doing it, whether
it's part of general relativity or not. I think time
itself cost inflation about that? Is that a new idea?
Lame Craig lame credit to that high fi novel. That's right,
that is officially your idea. And look forward to seeing
(33:24):
the paper you're writing on it. All right, let's get
into why we think costmic inflation even happened in the
first place, and let's get into what is still a
big mystery about it. But first let's take another break. Okay,
(33:50):
Daniel Lid we're talking about cosmic inflation, which is the
new Big Bang? Should we just call it the big
inflationary Bang, the Biggest Bang? Maybe the bangie inflation. But
so that's a crazy idea, that this idea that the
universe went from an infinitely dense infinity to a less
(34:11):
infinitely dense infinity in less than ten to the twenty
six seconds. That's crazy. It's crazy. But you know, the
universe and reality are no stranger to absurdity, right, They
don't care what your definition of crazy is. Yeah, and
crazy stuff has happened. And that's one of my favorite
things about physics is learning that the universe is bonkers,
(34:32):
bonkers beyond our imagination sometimes so it stretches our concept
of reality completely. I guess my question to you is
why do scientists think that so much happen is such
a short amount of time? You know, basically, why do
we think that the Big Bang or the inflation happened
in the first place. Yeah, well, it solves some problems.
It explains some of the things that we see that
(34:54):
we can't otherwise resolve. I mean, you might come up
with another theory that explains what we see out there,
but it has to explain all the stuff that we
see and tie up all the loose ends. And one
of the things is what we mentioned earlier on is
that we seem to be at the center of the
universe and that doesn't make sense. And the the hot Big
Bang model we have a point that explodes out, but
(35:14):
it does explain what we see if the whole universe
was infinite and expanded out everywhere at once, because then
everywhere looks like it's at the center of the universe.
It's like you're in the middle of a loaf of
bread and all the reasons as it's baking, all the
reasons are moving away from you. That's true, no matter
where you are in this infinite loaf of bread. Yeah,
(35:34):
it's like being in a rubber sheet. Right when you
stretch it out wherever you stand, it looks like everything's
blooming away from you. Yeah, exactly, And and that's pretty compelling.
But then you might ask, all right, well, that just
requires that the universe is infinite and it is filled
with an infor amount of stuff. Why do you think
it had this crazy expansion? And part of that comes
with what we see out there in the universe is
(35:56):
that the universe is pretty smooth. I mean, there are
clumps and galaxies and solar systems. Will get into that
in a moment, but if you average out over it,
it looks pretty smooth. And most specifically, if you look
at this cosmic microwave background radiation, this light we've talked
about that comes from like three hundred thousand years after
the Big Bang, when the universe was a hot plasma.
(36:19):
We see that light and we use that light to
measure it's sort of the temperature of the universe by
the frequency of the light. And it's really really, really smooth.
Like it looks like the universe was basically the same
temperature everywhere. And that's weird. It's it's very even, right,
It's like it it all, it all looks the same
almost from every direction. Yeah, it looks like a smooth bath,
(36:43):
you know. It looks like the temperature varies by one
part in a hundred thousand or one part in ten
thousand from here to there to the other place. And
you might be thinking, well, what what's weird about that? Right, Well,
it's weird from the point of view that those things
are cosmically far upon heart. If you look at light
that's coming to us from one direction in the cosmic
(37:04):
micro background radiation, it's been traveling the whole history of
the universe, just got here. If you look from the
other direction, life coming from the other direction has also
been traveling the whole history universe and just got here.
So it's the first time they ever met, right from
different ends of the universe. Right, one of them came
from the left edge of the universe and the other
one came from the right edge of the right. Yeah, well,
(37:27):
even if there aren't any edges, they came from totally
separated spots, spots that have not had time to talk
to each other or communicate in any way since the
beginning of the universe. Right, that's weird. That's weird because
they're the same temperature, and the only way you can
get stuff to be the same temperature is to let
it mix, Right, Like if you put an ice cube
(37:48):
into hot water, then you have a cold spot in
your water, and you have to wait for things to mix,
for the temperature to get so even. And so it
looks like the universe had a chance to mix. It
looks like the temperature smoothed out. But how did that happen?
Because these things have never had a chance to talk
to each other before. Why what? What if it touch
(38:09):
is how the universe was before? Yeah, it could be.
You know, a lot of these problems are sort of aesthetic.
You're like, well, I don't really get it. I don't
like that assumption. And so you could say, well, the
universe were just created like perfectly smooth. Yeah, just came
off the factory floor, nice and nice and toasty. Yeah,
(38:29):
nice and toasty. It's not exactly smooth. We see little
clumps in there, and the distribution of those clumps is
another thing that's explained by inflation. But you're right, this,
you know, by itself, this smoothness problem is not completely bulletproof. Right.
You could say, maybe the universe was just created almost
perfectly smooth, like maybe when photons are creative at the beginning,
(38:53):
they all have the same temperature. There would be another
way to explain it. There would be another way to
explain it. But the explanation that comes from inflation and
is that these things did once have a chance to mix.
That you know, before inflation, these photons, which were ten
billion light years apart, were only a meter apart. And
so there's a lot of time in this early plasma
(39:13):
for stuff to slash around and for things to get
smoothed out and for the universe to get to an
even temperature before things got inflated. Right, And so I
think I remember this that the the the way that
this explains it. It is that you need this kind
of rapid and violent expansion of space to basically take
(39:33):
the left edge photon and the right edge photon far
enough apart where it makes sense now. Yeah, so these
two have had to been inside the same sort of
cosmic horizon before, and now they're outside the cosmic horizon.
Cosmic horizon is something that is so far away that
(39:54):
you have not seen it because light from it has
never reached you in the history of the universe. Right,
there's a no way they could have talked before, And
yet it seems like they had have talked before. And
the expansion of space faster than the speed of light
is the thing that can do that. It can take
things that were inside the same cosmic horizon, right, that
are close enough to interact and talk to each other,
(40:15):
and smooth them become the same temperature, and push them
apart into their own separate cosmic horizons so that they
can no longer interact. And so that's what we think
we see now is that light from this from two
directions in the universe is now the same temperature, even
though without cosmic inflation, we don't think that they could
ever have met, right, It's like it's like a crazy
(40:36):
thing you've see in the universe that can only be
explained apparently by this crazy idea of inflation. Yeah, precisely.
That's one reason why we like inflation. It explains that.
And more specifically, the universe is not all the same temperature.
If you look at the cosmic microwave background radiation, this
light from the early universe, we said, it's like the
(40:58):
same too, within one in ten thousand, one in a
hundred thousand. Those wiggles are actually important. Those those deviations
from being exactly the same temperature are really important, and
we study those really carefully because those are the seeds
of the rest of the universe, right, that they're the
wrinkles that came from basically this giant stretching of the universe. Yeah,
(41:18):
those those wrinkles came from the giant stretching. And you
might wonder, like, all right, say the universe was created
perfectly smoothly, like you were saying earlier, Right, why couldn't
just come off the factory floor, like totally homogeneous. Well,
if you have a universe like that, then you never
get any sort of clumping. You don't get anything like
solar systems and hamsters and galaxies and stuff, because everything
(41:41):
is perfectly smooth and there's no place where things start
to clump together. To get any sort of clumping or structure,
you need something and that's not homogeneous, right, And so
you're saying, inflation is our only explanation for why the
universe is smooth and clumpy just the right amount that
we see it right now. That's right, because in physics
(42:02):
we have only one way to introduce random clumpiness, and
that's quantum mechanics. So the idea is the universe was
really really dense and perfectly smooth, and then quantum fluctuations
just like created a few particles here and a few
particles there. Now, normally, when that happens, and it's happening
all the time, it's not a big deal because there
are the quantum level so you don't see them. But
(42:24):
what if just when you're making those fluctuations, the universe
decides I'm gonna blow this up to ten billion light years?
Then all of a sudden, tiny little quantum fluctuations become
really big cosmic fluctuations, right, they become spread out over
the whole cosmos. Then they're big enough to seed gravity,
to get things moving, to clump stuff together. Right and
(42:46):
if so, so, if an inflation was not as dramatic,
then we wouldn't see those quantum fluctuations, right, because let's
say that inflation had actually taken longer than you wouldn't
you know, it wouldn't stretch those quantum fluctuations because things
would even out before you stretch out to the to
(43:07):
what we see now. Yeah, And that's why you need
to have inflation happened at the scale that had happened
like so dramatically and so quickly. You've got to catch
those quantum fluctuations with their pants down. Otherwise it doesn't
explain the universe were in. That's right, Their cosmic embarrassment
is the reason why we are here. Yeah, that's sort
of basically right, right, Like, it's like you needed to
(43:30):
catch the universe just the right time with this crazy
expansion like this photograph in order to explain what we
see now. Yeah, And we talked on the podcast recently
about another possibility, another different idea, which was cosmic strings.
People thought, maybe cosmic strings are the reason why we
see this sort of distribution of stuff in the universe,
but people look at them more carefully and it doesn't work.
(43:50):
You don't get this sort of the right kind of wiggles,
you don't get the right distribution of stuff here and
stuff there. But inflation gets it just right. Inflation says,
if you had that really dense plasma and then you
blew it up really quickly, you would expect to get
just the right density of stuff to form the kind
of structure that we see today, And there's no other
way to explain it in such fine detail that we know.
(44:13):
I mean, there are some other crazier ideas, but none
of them work as well as inflation, right, Yeah, Like,
if inflation at lasts it tended to the negative thirty
one seconds instead of tend to negative thirty two seconds,
then you and I wouldn't be here. Yeah, it would
be some other podcasts which would be not nearly as funny.
It would probably be over quicker. But there's a there's
(44:34):
some something else there. There's a real randomness right, Like
it tells you that the structure to universe, Like why
does a galaxy here comes from some like electron fluctuating
out of the vacuum fourteen billion years ago, And if
it had fluctuated in a different direction, we'd have a
different galaxy somewhere else. Like those tiny little quantum rolls
of the dye determine the specific structure of our universe today.
(44:57):
It mind boggling to think about. And they're super sensitive, right,
and totally random, super sensitive and totally random. Yeah. Wow.
So we we are lucky to have the universe we
have right now, and you listeners are lucky to have us, frankly,
and we are lucky to have you. We are very
glad that you fluctuated into existence. We are all lucky
(45:18):
to have each other. I think is the new theme
for Okay cool. I feel like I really understand there's
a little bit more, you know. It's it's like this
idea of an infinite infinity going less dense is and
very quickly in order to explain what we have now.
So does that mean, Daniel, that we know everything about
inflation and what happened at the beginning of time? Or
(45:39):
are there still things we don't know? There's not an
infinite amount of stuff that we don't know about inflation,
infinitely amount of stuff we don't know about an infinite
lead dance infinity that gets less infinite. Yeah, as our
knowledge grows, it feels like our ignorance is also growing,
or like our knowledge of our ignorance is inflating as well,
you know. But that's the fun part about science. I
(46:00):
think the biggest mystery about inflation is like what caused it?
What made it happen? What could possibly expand space at
this crazy rate? Right? Like why didn't the universe just
stay the way it was before? Why did it have
to have this crazy expansion? Yeah, and why did the
expansion stop? And so as usual, we don't have any idea,
but we've already given it a name, and of course yeah,
(46:22):
we've we've called it the infloton not a joke. I
know it sounds like I'm making that up. But created
this field called the infloton field, which would have an
infloton particle, and the ideas that this field causes this
crazy expansion. It sort of just puts off the question like,
all right, well, what creates the inflotton field and what
(46:43):
controls it? Well, we have no idea, but it's just
sort of like a place to put our ideas. Interesting,
So we owe our existence and our universe to the
infloton Yeah, and the infloton The idea there is like
the universe is filled with this infloton field, which expands
space and sort of decays into ordinary matter. And that's
(47:04):
how you get ordinary matter. You have in photon field,
which then turns into corks and electrons and other kinds
of fields. Um. And we don't know like what would
cause that decay, Like that's when inflation stops, is when
it turns into normal matter. But we don't know like
why would it stopped and or why was it there
in the first place? Yeah, what was there first place?
And also did it stop? Like there might be it
(47:27):
might be that inflation sort of stopped in our part
of the universe, but it's still going on in other
parts of the universe. Could be the rest of the universe.
We're like in a little bubble, a pocket universe, and
the rest of the universe is still inflating. And imagine
how far If it got that far in ten of
the minus thirty two seconds, imagine what it could do
in fourteen billion years. Wow. So you're saying that maybe
(47:50):
we are even more insignificant than we had previously imagined. Yeah,
that's this idea. It's called eternal inflation. That the universe
is continuously inflating, and occasionally the inflation sort of decays
into normal matter, and then you get the kind of
universe we're familiar with, but that most of the universe
is just this massively expanding infloton field. Wait, are you saying, Daniel,
(48:11):
that the infloton works in mysterious ways? I'm saying exactly that,
mostly because we don't understand it at all, And so
can I start a new religion based on the infloton?
Are you the high priest of the inflation here? Yeah,
because I am both the high priest and the parishioner
of my church of the Inflaton. Yes, please donate to
the Church of the Inflaton. I think we just replaced
(48:35):
the spagetti master. Yeah, and so of course this feels
like a big place holder because it is we don't know,
and so it's just a way to say, if inflation happened,
what's a possible way it might have happened. And then
let's start to get to work on, you know, figuring
out how that theory has to look. Step one, give
it a science names and then figure it out. Step
(48:56):
to get ridiculed by Jorge. Step three, get to work alright. Cool,
It sounds like there's still lots of answers to be
found in this and these are important answers, right, I
mean they're they're about the beginning of the universe and
why are things the way they are? And are things
going to change in the future. And you know, I
think in ten years or in twenty years, people will
(49:18):
look back at these ideas and think, oh, my gosh,
how absurd. I can't believe they really believe that stuff.
Because we're going to learn things about inflation, and we're
going to learn things about the history of the universe
and its current expansion that are going to give us
better ideas, even crazier ideas that are going to be
even more correct. And so this is the perfect example
of how our knowledge of the universe is constantly expanding.
(49:40):
We look back and think, wow, how silly. Yeah, you
know they say twenties smart physicists are twenty thirties ignoratons.
That's right, Yeah, I have twenty twenty vision, which means
I look back at ten and think one a bunch
of ideas. Well, I can't wait to have visions. That's
(50:00):
what happens in our old age, right, we all get
reading to us is all right? Well, maybe we'll get
into these mysteries a little bit deeper in the future podcast,
but for now, thanks for joining us. We hope you
enjoyed that. We hope we inflated your mind and took
you on a tour of the early universe. Thank you
very much. Before you still have a question after listening
(50:26):
to all these explanations, please drop us a line. We'd
love to hear from you. You can find us on Facebook, Twitter,
and Instagram at Daniel and Jorge that's one word, or
email us at Feedback at Daniel and Jorge dot com.
Thanks for listening, and remember that Daniel and Jorge Explain
the Universe is a production of I heart Radio. For
more podcast from my heart Radio, visit the i heart
(50:49):
Radio app, Apple Podcasts, or wherever you listen to your
favorite shows.
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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