What is the cosmic microwave background?

Daniel is joined by guest Dr. Crystal Dilworth to discuss the cosmic microwave background.

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Episode Transcript

Speaker 1 (00:08):
Crystal, did you know that the secrets of the universe
are all around us? What? Where? No? I mean answers
to some of the deepest questions in science are literally
all around us, like hiding under my bed or what
do you mean? Yeah, they're under your bed, but they're
also just right here in the air between me and you.
I guess Bob Dylan was right. What do you mean,

(00:31):
Bob Dylan? They're all just blowing in the wind. I
guess Bob Dylan was a poet and also secretly a
physicist and a philosopher, Which aren't We are doctors a
philosophy anyway. That's right. That doesn't mean we know anything
about it, but we have the title. Hi. I'm Daniel.

(01:03):
I'm a particle physicist and co host of the podcast
Daniel and Jorgey Explain the Universe, brought to you by
I Heart Review. My co host, the hilarious and good
looking Jorge Cham is not here today to join us
with his amazing jokes about bananas. He does love a
good banana, He does love a good banana. But instead

(01:24):
today we have a wonderful, amazing co host, Crystal Dilworth. Crystal,
introduce yourself. Hello. I'm Dr Crystal Dilworth. I'm a neuroscientist,
um my PhD s and molecular neuroscience, so the molecular
basis of nicotine dependence from cal Tex. So I'm just
a curious person that loves science communication and I'm super

(01:45):
excited to be here to talk to you today. All right, well,
thanks for joining us. So you studied nicotine addiction. Does
that make you um in the pocket for big tobacco?
It's a classic dilemma, right do you accept research funding
from big tobacco? Um? I was supported by ni H,
so I escaped that quandary, so you stayed clean. In

(02:06):
my field, it's always a question of do you take
money for weapons researchis you know, like my parents, for example,
worked at National Labs, work in weapons programs and helped
develop essentially weapons of mass destruction, whereas I try to
stay away from that and work on things that will
never affect anybody's life. So maybe there's a parallel there. Um.
But Crystal, you are a PhD scientist, but you're also

(02:28):
not just a scientist, right, You're a dancer, you're a
movie star, You're I guess I should have led with that.
So I became part of the PhD Comics universe, um
through the PhD movie. So I played Tagel in the
PhD movie and the PhD movie too, and that's how
I sort of came into ys Orbit and we've been

(02:49):
working together on and off to audition for a movie.
I mean, you ever acted before? I had acted in
children's theater, So nothing on camera, nothing serious that was
going to be seen on every continent on the planet.
And it was really hard for me because I had
started grad school thinking I was going to give up

(03:09):
my life in the performing arts. No more dance, no
more theater, no no stages for me. I was going
to be the best scientist anyone had ever seen. I
was going to eat, sleep, breathe science, do the right thing,
be a good person. Um. But I had been reading
PhD comics since I was working in the lab. And
when you get an email saying PhD Comics is coming

(03:32):
to your campus and they want to make a movie,
a live action movie or live action YouTube series about
this comic that has been your you know, your inspiration
for grad school? Do you want to be a part
of And it's like therapy for people, right. And I
traveled with or hate people who come up to him
and say, it hadn't been for your comic, I would
never have made it through grad school, right, I mean,

(03:54):
if it hadn't been for the comic, I never would
have gone to grad school. So that's that's a whole
other conversation shin before then, to blame you for your
grad school. Yes, they hold him very much to blame.
I don't know if he knows that, Jorge, it's your fault, um,
But yeah, it was just the carrot was too big.
So I was I was at a Biophysics Society meeting,

(04:16):
which is about three hours away from Pasadena at the
time that Jorge was running auditions for the PhD movie,
and I went to my last session, got in the car,
drove from San Diego up to Pasadena audition for the movie,
and then drove back so I could be there for
my eight am poster session the next morning. Like my
my advisor like as if as if I was never gone,

(04:40):
he would never know. Yeah, And that was sort of
the beginning of the end for me, because through working
with Jorge, I discovered that science communication was an area
that I could work in after grad school, and that's
what I do now. I host a show for a
Voice of America that highlights science and technology that's happening
here in the United States. It's broadcast internationally. UM I

(05:02):
was recently selected as one of the Triple A s
if THEN Ambassadors. I'm a role model for women in STEM.
Thank you, and I'm really excited about what that means.
And I've you know, I love doing these types of things.
I'm happy to sit down here with you and do
you feel like people these days still have to sort
of choose between having a career in science or having
a career in sort of the creative sector art, dance,

(05:24):
you know, public speaking, or do you think it's more
opening now for people to bridge that gap and live
two lives and not have to hide from their advisor
that they're doing this other thing. I think that the
Ivory Tower is still pretty restrictive in terms of what
it will accept for its tenure track faculty. But I
think that if you haven't chosen that as your path

(05:46):
to walk, there's a lot more leniency. UM. You asked
about careers. I think it's difficult to make a full
living in the arts and a full living in science.
So in that respect, Abe you would have to choose
one or the other. But there's so many exciting spaces
for collaboration. I don't feel that anyone should feel that

(06:08):
they have to give one of those up in order
to do the other. Well. I'm really excited about the
idea that science could be more open to more kinds
of people, not just people who look different or come
from different places, but people whose interests are broader, and
that we don't have to be only people who are
super zero focused on exactly this one kind of science,
and then they have other interests and they do other
things in their life. I think that's probably going to

(06:28):
be good for science and also good for science communication
if we have people from science who know how to
do this thing. In my lab, specifically, I encourage the
students to do science communication, send them to conferences, this
kind of thing. I don't know if that's good for
their careers or not, but I figured, since I try
to do science communication, that I should try to not
prevent my students from also doing it. I don't know
if that's a good idea or not, but on this

(06:50):
open minded process I'm experimenting on my students, but also
on this podcast, we want people to understand that everybody
can understand scien It's one of the goals of this
podcast is to zoom around the universe and take crazy,
amazing things and make them actually understandable, not just jargon
said while waving your hands, which isn't helpful on podcast,
but people can go away and feel like I get it,

(07:13):
I know what that is. I understand relativity now, and
I want to make breakdown those barriers and make people
feel like they can figure it out too. Oh I'm
all for that, all right, So let's get into it today.
We're gonna talk about something really amazing, as we alluded
to earlier, something that's all around us, a secret of
the universe, deep dark knowledge about how things in the
universe work, the ancient history of the universe that has

(07:35):
just been sort of floating around in the air around
us with nobody noticing for I guess thousands of years.
Literally like a color you can't see, yes, exactly, if
only our eyes could open it. I talk a lot
in this podcast about opening new eyes. I feel like
science is always figuring out new ways to look at
the universe, and every time we do so, we realize
the universe. Wow. It looks so different and using these

(07:57):
other eyes than than the ones we're familiar with. So yeah,
it's like a color that we can't see. And also
it's one of my favorite stories because it was discovered
kind of by accident. You know, Folks were trying to
do one thing, developed this technology, accidentally stumbled into this
incredible wealth of knowledge about the universe. I think that
there's a lot of really cool stories, especially in astro

(08:19):
about accidental major discoveries. That seems to be one of
the really big fields of science where that that's possible.
I feel like I'm so jealous sometimes with astronomy because
every time they look out into the universe with a
new device, they find something that doesn't make any sense.
We talked about recently the podcast These Fermi Bubbles. It's
like huge structure the size of the galaxy and nobody

(08:39):
ever seen before, found ten years ago. But whereas in
particle physics it feels sometimes a little bit more difficult
to find new things. It's rarer that we like find
a new particle nobody hadn't expected. Um. So sometimes I'm
jealous of astronomers because they get to they get to
see things they don't understand more often, and that's like
the launching point for discovery, right when the universe gives

(09:00):
you a clue and says, here's something you didn't expect,
then you get to unravel it. I feel like, for
a chemistry and neuroscience, which are my area, is like
the analogous story is like the discovery of LSD. Like
some chemist was like, what's this? I'm going to eat it?
And I was like, WHOA, Well that's the big leap
forward in neuroscience. So what were they trying to do

(09:23):
when they discovered LSD? I don't actually remember. It's like
such an irrelevant part of the discovery story that I can't,
off the top of my head even remember what they
were trying to synthesize. Al Right, well, today we're talking
about something unseen but then discovered something a surprisingly revealed
that told us deep knowledge about the universe. So let's
not tease it anymore. Today we're going to be answering

(09:44):
the question what is the cosmic microwave background? So this
is something which is invisible and carries a huge amount
of information all around us, and it discovered by accident
about fifty years ago. It's a pretty funny story. Actually,

(10:04):
some folks were building a radio telescope to do something else.
They want to do radar and communication, and so they
built this device and then they heard this buzz on
the device. Is this noise? And at first they were like, oh,
this is annoying and we can't get rid of it.
They thought it was like a malfunction of their telescope.
Um they couldn't understand where it came from. So microwaves,

(10:28):
can we just start there? I have one. I so
you're an expert in microwave backgrounds because you can use
a microwave. I can use a microwave. I'm an expert microwaver.
I'm not sure how to extrapolate my knowledge of heating
up soup to the beginning of the universe. Can you
help me draw that connection? Yes, for once our podcast

(10:51):
will actually have practical knowledge and it folks. Yes, we'll
draw that connection. But first I was wondering what everybody
knew about microwaves, Like, do people understand microwave back ground radiation?
Dos that make sense to them? Is this something everybody
is already familiar with or is it something nobody had
ever heard of before? And so, as usual, I walked
around campus here you see Irvine, and I'm eternally grateful
to the students here for being open to being asked

(11:13):
these random questions by a scruffy looking physicist. So before
you hear their answers, think to yourself, do you know
what the cosmic microwave background is? How could you explain
it to a random dude who accosted you on the street.
Here's what, folks that you see Irvine had to say
something that's ongoing in the atmosphere having to do with microwaves.

(11:36):
I don't know, no micro waves that are present everywhere.
I do not know. I've heard the topic. I've watched
couple of videos, but I don't understand that whatsoever. Wave
like yeah, I don't know it's material or just wave.
There is something like that a president outside Okay, I
don't know. It's a elemnent of those in a big thing.
All right, So Crystal, what do you think of those answers?

(11:56):
You impressed? Um, I don't think i'd say impressed. But
there's quite a diversity of topics that the answers are
connecting to, like electricity or something. Yes, yeah, well, it's
like electricity or something that's a pretty broad answer, so
it's pretty close. You could tell that some people had
no idea what we're talking about and just sort of

(12:17):
guest generally physics. A few people had heard of it.
I like think, I said, I watched a couple of videos,
but I have no idea what it is that tells
me that there's an opening here to really explain the
microwave background. She really needs this podcast, Yes, exactly, this
one is for you, dude. But I like the I
like this answer remnant of the Big Bang. I mean,
we're really getting to something there, aren't we. Yes, absolutely,

(12:40):
somebody definitely knew what we were talking about. So let's
get back to your question and break it down. I
know how to heat up soup in a microwave. I
even know that microwaves are long radio waves. I think
of them as really big waves. I mean, I'm a
I did a lot of fluorescence microscopy UM in a lab,
so I like nanometer is a scale that I'm used

(13:03):
to dealing with in microwaves, I think of being so
big as to be ineligible. UM, so help me out here. Yeah,
I love this sense of scales and science right for me.
For example, anything big on the proton is like way
too big and complicated even think about, right, whereas mechanical
engineers never think about the individual molecules. So microwaves is

(13:23):
really really just a relative term. Remember, microwaves are electromagnetic radiation,
just like light. So everything that's coming into your eyeballs
is electromagnetic radiation, but it's part of a much larger spectrum.
The visible light is just this one little slice that
we happen to be able to see because our eyes
react to it. But down the lower um frequency, the
longer wavelengths, you have radio waves, and at the higher

(13:45):
end you have gamma rays and X rays. It's all
just part of the same big electromagnetic family. And microwaves
are a kind of radio waves, as you said, and
they're might be called micro because they're short for radio waves.
Radio waves can have wavelengths like meters long. It's just
all about scale, it's all about scales, and so compared
to that, microwaves, which have wavelength like millimeter, are really small.

(14:06):
But of course you know, they're huge compared to visible
light or gamma rays or anything that I know anything about. Frankly,
So microwaves are mega waves for me and microwaves for
most people. So cosmic microwave background. The connection is the
wavelength of the electromagnetic radiation. And we talked on this
podcast recently about how microwaves work, and they work in

(14:27):
the same way. They pump this same kind of radiation
into your soup to make it hot, using it to
add energy to the system. That's right, Um, and then
fueling you so that you can think about the universe
and reveal all of its secrets. I'll work on that,
all of the secrets revealed. Yeah, exactly. Um, Jorge usually
has a banana before every podcast because apparently he can't

(14:48):
think without a Is that's something you know about him
through I know that he definitely does not operate without
a banana. I do not operate without a coffee. So
as long as he's got bananas and I've got coffee,
we're usually good to go. That's all that's required around here. Well,
this is a perfect spot to take a break. We'll
be right back. Um. Yeah, So, cosmic microwave background radiation.

(15:20):
The microwave radiation part just refers to the length of
the waves of the electromagnetic radiation. So where are the
waves coming from? Yeah, they're coming from everywhere, Like if
you look out into the sky, you see this radiation
coming from everywhere. And that was the weird thing about
their discovery. When they turned on this radio telescope for
the first time, they heard this buzz and they heard

(15:41):
it from every direction. There's sort of two answer parts
to that answer. One is where do we see them? Right,
And it's coming from every direction, so we see it
from everywhere in the sky. And often if you see
a map of the cosmic microwave background radiation, it's this
weird ellipse with these little dots on it, and that's
an attempt to describe what you see in each direction
the sky. So, because the sky is a circle, right,

(16:03):
the Earth is a sphere. It's hard to map a
sphere onto a flat piece of paper. The best way
to describe what you see is if you could print
it on the inside of a sphere, so you could
look at and say, oh, in this direction, we see this.
In that direction, we see this. The same way, it's
hard to make a map of the stars you see
in the sky, right. The best way to do that
is like a planetarium, you can print them on the
inside of a curved surface, so you can show what

(16:25):
we're seeing. So what we see when we talk about
the cosmic microwave background is we see this buzz, this
electromagnetic radiation from every direction at once, so just filling
the space that is the universe. Yeah, it's coming from
every direction and hitting us. And it's everywhere. Like if
we were here or around Jupiter, or in the center

(16:45):
of the galaxy or in between galaxies, we would see
it everywhere. So it's originating from the universe. It's just
an energy that now exists and bounces around and comes
from everywhere. Yeah, it comes from everywhere. And that's the
confused seeing part, I think to a lot of people,
because people think, Okay, it's light, so it's traveling at
light speed and it's getting here. How can it be

(17:07):
getting here? Where did it come from? Right? And that's
pretty confusing if you imagine that, if you think about
the beginning of the universe as a point and from
that point things flew outwards, and people trying to imagine, well,
then if it's getting here now it's coming from that point,
how can we be seeing it from two directions? And
the reason that's confusing is that I think that's the
wrong way to think about the start of the universe.

(17:28):
Oh my gosh, how should I be thinking about the
start of the universe. Well, you start with the bowl soup, right, Um. No.
The way I think about the start of the universe
is that it started off infinite, that it's the moment
of creation is not a single point in space, but
that the Big Bang happened everywhere all at once. There
was sort of multiple starts from every direction. And what

(17:49):
we're seeing now is leftover bits from really far away
in that in one direction, and really far away in
the other direction. So if I'm looking at the cosmic
microwave background reradiation, I'm seeing light that came from the
very beginning of the universe. It took almost fourteen billion
years to get here from somewhere really far away in
one direction. And I'll turn around and I look in
the other direction. I'm seeing light come from the other direction,

(18:11):
which came really far away from the other direction, from
somewhere else, really really far away. So these two pieces
of light haven't talked to each other ever. Are they
meeting for the first time in the history of the
universe here on Earth. So they're not coming from the
same place. It's not like we're looking at a little object.
We're looking at a huge universe at its beginning. Every

(18:33):
direction you look at, you're looking at a different part
of the early universe. So does that mean that the
different particles, the different waves of light that are meeting
here for the very first time can tell us different
things about the beginning of the universe. Yes, absolutely, they
tell us what was going on at one spot of
the universe over there, and what was going on at
one spot of the universe over there, just the same
way when we look at the night sky. Now you

(18:55):
look at one star, it's telling you that light is
telling you what happened a long time ago in that direction.
You turn another way, and like from another star is
telling you what happened in a totally different part of
the universe, also a long time ago. Those two photons
are also meeting for the first time. So I have
a lot of questions about how that information is carried
and decoded. But first I'd like to ask, when this

(19:18):
background radiation was discovered, what did we think it was.
How did we know that it could teach us and
tell us things. Yeah, if that's a really fun part
of the story because the guys who discovered this, they
weren't looking for it, but there was another team of
people who were looking for it, and they got scooped.
So there was a team around the corner. This telescope
they built was in New Jersey and it just happened

(19:40):
to be around the corner from Princeton. It was a
team of Princeton who was looking for this radiation. They
were like scrambling to build the device. They could see it,
and they got scooped by these guys who were like
building something to do something else. The reason they were
looking for it is that there was this idea that
we could find evidence for the Big Bang. And this
is back in the sixties when the Big Bang was
still like kind of a crazy idea, not neces serily

(20:00):
totally accepted. Definitely not a television show, yeah, not yet,
a hilarious television show that probably gates stereotypes about scientists. Um.
But the idea was that if the universe had started
smaller or more dense right at the universe had started
from um really dense mass and then exploded, then originally

(20:22):
it was sort of hotter and denser. And the reason
people thought that this radiation might exist. Is that they
looked back into the history of the universe. They said, Okay,
the universe now is a bunch of stars and galaxies,
but if there had been a big bang, then the
universe we sort of rewind the history of the universe.
Everything pulls together and gets hotter and denser, and eventually

(20:42):
it gets so hot and dense that it becomes a plasma.
And a plasma is really interesting because light can't just
passed through it. It's opaque. So this this moment in
the history of the universe they thought when the universe
went from opaque like like couldn't go through it too transparent,
Suddenly the universe cooled um and became crystal clear, so
that you could, like photons could fly through the universe

(21:02):
without necessarily getting absorbed. And so this is this last
moment when the universe was a hot plasma and then
it cooled, and the light from that moment, they figured
should still be around. That's crazy. I know. It's like, um,
you know your baby picture that your parents took, you
know whatever, years ago. Um, the light from that picture
is still out in space somewhere. Like that's literally true.

(21:23):
I was thinking, like gestational periods of the universe, which
was like a really weird mental trip that I just
went on and back. Now, okay, welcome back, um. But
you know the same way that everything that happened on
Earth a long time ago, the light from that is
out there in space, the way like TV shows that
we broadcast are out there in space flying away. Um,

(21:44):
everything that happened in the early universe is still out
there in space. So if the early universe used to
be hot and dense and then all of a sudden
became cool, then this light could fly through the universe
untouched and it should still be out there. And that's
what they were looking for. They were looking for this
last light from the hot plasma other early universe, which
should then still just be flying around and we should

(22:04):
be able to find it. And you know microwave background.
Remember that's just another kind of electromagnetic radiation. So when
we're talking about light, we really just mean electromagnetic radiation.
So finding this radiation meant that we were on the
right track in terms of the origins of the universe model. Yeah,
it was really the first experimental evidence that said, wow,
this crazy idea that the universe used to be hot

(22:26):
and dense and then expanded really fast. Might be true.
It's you know, this rhythm and science where we say, okay,
you've got a crazy idea that sort of explains the
way things work. Make a prediction, prove it, predict something
that we could find that we could only see if
your idea is correct. And this is what was the prediction.
And coincidentally, Jim Peebles, one of the guys who predicted it,

(22:47):
just won the Nobel Prize for that prediction this very week.
The competing idea at the time was the sort of
steady state universe. Universe had been like this, been like
this forever. You know, maybe it was expanding, but there's
some sort of new source so stuff in it, and
that people wanted to believe that. I don't really understand
why people wanted to believe Biblical origins. Don't you think

(23:08):
we'll see but biblical origins tell you the universe had
a beginning, right, The steady state idea sort of like
the eternal universe. The universe has been like this forever,
And for some reason, I think that seemed more natural
to people. It seems more natural to me that the
universe had a beginning. I guess to some people, thinking
the universe had an origin brought up other questions like
what happened before that? And I'm not afraid of questions.

(23:29):
I love those questions, But to me, it would be
weird at the universe it existed forever. I was actually
trapped at the Caldec Faculty Club while a visiting professor
and one of our staff scientists had an argument over
what came before the Big Bang, and none of the
graduate students were willing to interrupt the argument to say like,
can we order because we're really hungry, and the waiter

(23:53):
kept coming to take our order, and the graduate students
kept making eyes at them like were we we can't
They're still argue. Eventually, I think somebody came and was like, sirs,
can we move this process along? But I guess this
is still a hotly contested idea, at least in the
Caltec fact of the club at lunchtime. Yeah, and you know,

(24:13):
sometimes this arguments can feel like they last forever um.
But at the time there was these two camps. It
was the steady State University. University existed sort of in
this similar state forever, and the other idea that it
came from this hot, dense initial point. And this was
the prediction that that they made that if the universe
had been hotter and denser, it would have be this
plasma and it would admit this radiation and we could

(24:34):
still find it. You know, it's like if you, um,
if there had been a rave in an apartment last night,
and you know, you expect like lots of loud music,
and the moment that music turns off, that music is
still flying out there somewhere. So this is like saying,
let's go find that music as evidence that there was
a rave in my apartment last night, But of course
that music is flying off away from us. You would

(24:55):
have to like travel the speed of sound to catch it.
This is like that we're finding here. So I think
it can be a little confusing to digest, like why
are we seeing that light here? And seeing it from
multiple directions. So when it was detected or discovered, the
scientists knew what they had, and they also knew that
there were some were going to be some really upset

(25:15):
people at Princeton Um. They didn't know what they had,
Like the guys who found it, Penzias and Wilson, they
just thought it was noise. They just heard this hiss
in their telescope and it was an obstacle to them.
They thought, we can't get rid of this. What was
going on? Um? And they're like, this is really strange.
And then they went around the corner to the physicist
of Princeton and they're like, we found this weird thing.

(25:36):
What do you know about it? And I think the
physicist must have been like, oh my god, we've been
trying to find this and you scooped us slash. Wow, wonderful,
we learned this amazing thing about the universe. That must
have been a really sort of you know, plus and
minus moment for them. So they published it separately. There
was no post talk collaboration. Now they wrote two papers.
The guys who actually found it published their discovered, like

(25:58):
here's what we found, and then immediately afterwards the Princeton
guys wrote a paper saying here's what this means and
here's why it's important. But the Penzias and Wilson, they're
the ones who got the Nobel Prize because they're the
ones who found it. Man, science sometimes it's luck, yes,
I know, And you can be like days or weeks
away from a discovery that wins the Nobel Prize, if
those folks at Princeton, if their grad students had worked

(26:20):
a little harder, or they hadn't taken us along to
order lunch. Professor. When I was an undergrad professor of
mine who was teaching thermodynamics, he was one of the
folks racing to discover the Bose Einstein condensate, this weird
state of matter, and there were other groups. Was when
m I T and when it nised and he was

(26:41):
able to create the Bose Einstein condensate and published it,
but he was two weeks too late, and he was
left out of the Nobel Prize. So there was shared
between NIST and M I. T. And he was two
weeks away from the winning the Nobel Prize. And I
always thought, wow, that must be tragic, and he must,
you know, wonder like should I have given my grad
students two weeks off for Chris Smiths or we could

(27:01):
all be sharing the Nobel Prize right now? Right, I
feel like we should probably move on because I could,
I could take this topic my soapboxman really want to
be you know right now. But it's true, right, like
these these things can be so so far yet so close,
and you never know. You never know if you're around

(27:22):
the corner from discovering something amazing, and also if somebody
else is one week ahead of you, or if you're
sort of on your own and you're about to discover
this incredible thing. That's the pressed grad students showing up
in the lab every day, right, is the hope that
the next day is going to be different. It's also
the definition of insanity. That's right slash of research. So

(27:43):
when the Princeton group published sorry to bring us back,
when the Princeton Group published their paper saying this is
what the discovery means, what did it mean? Yeah, it
meant that there was this evidence that the universe had
once been hot and dense, and since the universe is
dot hot and dense right now, it's like huge and
empty and cold. That means that the period of the

(28:04):
universe we're living in is not the way things have
always been, and it means that the history is quite different.
And we found relics of the history. This is like
fossils of the universe. It's like a discovering whoy there
there used to be these huge, crazy animals that walked
along the Earth. Earth used to be totally different from
what we're experiencing now. Now this is on the universe scale.
Now we learned whow the universe used to be this hot, dense, nasty,

(28:26):
wet plasma where nothing could probably get through and then
it cooled. And so that was really very convincing um
evidence that the Big Bang was a real thing, and
the Big Bang like happened. It's not just an idea,
it's not just a story. It's not just something you
read about in the book. It was reality. It was
it was these physical events took place. H And to me,
that's amazing. You know that there's there's this history of

(28:48):
the universe and we can uncover it, that there's enough
clues out there that we can actually figure out what
the objective truth is of the universe, which has sort
of been like a big question in human existence, right
where do we come from? How has this whole thing
been created? We're unraveling that. We're like using science to
figure out what the true history of the universe is.
That's incredible power. So when you're talking about objective truth,

(29:12):
is this things that can be described using mathematics. Yeah,
we have models that described the early universe, and those
models made predictions, and those predictions are born out to
be true. And you know, we can never really claim
objective truth. We don't really know what's out there. You
can just be trapped in a brain, in a vat somewhere.
You don't know if the universe exists. But assuming that

(29:32):
the things that we're experiencing are real and that physics
can describe them, we're making incredible progress in revealing the
way we think the earlier universe happened. And I think
that's pretty incredible. As a physicist, you know that there
is a noable truth that is always true, at least

(29:52):
within the universe that you yourself are experiencing. Yeah, that's
one of the things I like about physics. I mean,
I love doing creative stuff also, But the thing I
like about physics is that the universe answers questions and
it's you know, yes or no. It's not like, well, uh,
you know, you wrote this thing, this novel and it's
pretty good and somebody else's no, it's wonderful, somebody else's no,
it's trash. Right, the universe, you can ask a question

(30:14):
to say, all right, which theory is correct? And he
says this one and that one. You love it. It's beautiful,
but it's wrong. There's an objectivity there. It's not just
people's opinion. You know, the universe tells you this is
the way things happen. But only if you can find
those clues, only if you can figure out a way
to sort of corner the universe and make it reveal
this truth. You don't just get to stand in a

(30:35):
mountaintop and say, tell me the answers. You have to
figure out a way to find these clues and on
earth it like a detective and that's a slow process. Right.
If you think about early interpretation of physical fossils like
you know, dinosaurs, et cetera, or you know small ce creatures.
We use that to fuel stories of monsters and uh,

(30:56):
it evolved the way that we were describing our universe
are our world, but not necessarily to bring it completely
in line with the scientific understanding we have now. So
how long did that process take discovering this fossil of
microwave background? Yeah? Well, I think the idea of the
Big Bang dates to the earlier part of the last century.
The whole idea that the universe was bigger than the

(31:18):
galaxy is only than only a hundred years old, and
then so discovering these other galaxies, finding that they're moving
away from us, and then trying to understand, well, if
the universe, if galaxies are moving away from us, right,
then how can we have a at all a sort
of steady state model? Thing? Before that people imagine galaxies
just sort of hanging in space. So then discover things
are moving away from us, that's sort of immediately implies

(31:40):
some sort of expansion. And then that brought up these
questions like, well, how can you have expansion if the
universe is bajillions of years old? And Einstein didn't like
that at all either. That's really the origin of that idea.
And so then to find this evidence is really conclusive.
And then they discovered on top of all that evidence
that this is really from the Big Bang. There's a huge,
huge amount of detailed information in this buzz, in this

(32:03):
light from the first plasma that gives us clues about
what was happening in the Big Bang, the way like
you can look at your baby picture and be like, oh,
I can tell like you know, I'm drinking coffee as
a two year old or whatever, or Orge has got
a little banana his baby picture. Um, you can look
back at this baby picture of the universe and and
understand why our universe looks the way it does and
gives us a huge amount of information about our universe today. Well,

(32:27):
this is a perfect spot to take a break. We'll
be right back. So how is that information coded. It's
coded in the little differences. So if you look at

(32:48):
the cosmic microwave background radiation maps, and if you're in
front of a computer, you should google cosmic microwave background
and you'll see this image. It's sort of like reds
and blues and greens. And what you're seeing there is
that is this slightly different energies you see if you
look in different directions. So you get this radio wave
it's microwave, and that has a certain frequency, and their
frequency means a certain energy and there's very small variations. UM.

(33:12):
And so what we do is we measure the energy
in different directions and we see that in some places
it's like one one hundred thousands hotter or one one
thousands colder, and that's telling us something about the density
of that plasma. Four hundred thousand years after the Big
Bank fourteen, almost fourteen billion years ago telling us, oh
this was a hot spot, this is a cold spot.

(33:33):
And those are very small variations in sort of the
temperature of the universe at that time. And you might think,
well that why does that matter, alright, who cares about
the tiny a little bit hotter, tined, a little bit colder. Well,
those are the structures, the seeds of the structure of
the universe itself. The universe has been totally smooth, like
exactly homogeneous everywhere, and there's no way to sort of

(33:55):
build anything because every particle is being pulled in every
direction simultaneously. What you need to start the seed structure
to get like galaxies and planets and stars and people
and bananas and hamsters is you need a little bit
of variation. And so these are the original seeds of
variation that caused the structure that we see today. So
if everything was all the same, maybe you're really boring here. Yeah,

(34:20):
we wouldn't be here because that you would never form
any structure. You would never form really hot, dense things
like stars to give light and planets for people to
live on. It would just be smooth and not very dense.
So in order to get anything interesting in the universe.
You need little packets of density to start off with.
And if those packets were even slightly different, our universe

(34:40):
would be so completely different we wouldn't even recognize it. Yeah,
you wouldn't have a galaxy here, You might have a
galaxy somewhere else, totally far away. Yeah. And the amazing
thing is that these those variations are totally random. They
come from quantum mechanics. Like, where do you get these
variations from the beginning? The universe started out sort of symmetric,
and how else could it start? Then? How you get

(35:00):
any variation to see the structure comes from quantum mechanics.
Quantum randomness strikes again. It keeps following me around. It's everywhere.
So you get little random fluctuations. Those little fluctuations get
expanded into bigger fluctuations, and then they become, you know,
larger and larger. So we said, see these really really minor,
very subtle fluctuations in this early plasma. You know that

(35:21):
took fourteen billion years for gravity to build on and
to make something big and beautiful and elaborate that we
are living in today. So for scientists starts studying the
cosmic microwave back on the c MB right now. Are
they asking questions about the past or are they looking
at either at present time or future time? Yeah, that well,

(35:44):
that's a great question. I think people want to understand
the past because they want to know the future. Like
I'd like to know how long is the univer is
gonna be around, is going to keep pairing itself apart
or turn around and crunch? And part of answering the
questions about the future means looking into the past and
understanding the origins and revealing the mechanisms. So I think
we're asking mostly asking questions about the past, but really

(36:04):
because we want to know the answers about the future.
And the CNB reveals all sorts of things like how
much dark energy was there, how much dark matter was
there in the very early universe, how much matter was
there in general, All sorts of things are encoded in
the details of the CNB, And that's the kind of
thing that scientists are focusing on today's is pulling out
as much information as possible from this early map of

(36:25):
the universe. So this is just one of the many
types of radiation that I can't see that's being like that.
I'm basically swimming through as I go about my day.
Imagine if we were all blind, humanity was all blind
and nobody could see it would be difficult to imagine. Oh,
there's all this information around us that we're not capturing,

(36:46):
and the light would be there, but we just wouldn't
be using it to understand our world. Well, that is
our situation. We are all blind. We're blind to all
these different other kinds of light and particle that are
all around us with incredible information about the universe that
we just can't see. In hill, we build telescopes and
new devices that are sensitive to these kinds of radiation
and these particles that can help us understand these clues.

(37:08):
What's the most mind blowing thing about the CMB that
you ever learned? And can you describe that moment? Yeah.
The thing that I think is amazing about the CMB
is that we can see sound in the CMB, Like, okay, wait,
we can see sound. Yeah, we can see sound. So
what is sound? Sound is waves? Sound is a like ripples.

(37:30):
So for example, you're sitting your bathtub and you move
your arm, you see waves in the water, right, So
those are waves. Sound is just waves in air. So
when we say, well, maybe instead of saying sound, I
should have said we see ripples. We see waves in
the CMB, we see ostillations because there's some kind of
matter in the early universe, in the early plasma that
can interact, like pulls itself together like normal matter, and

(37:53):
some matter that doesn't, like dark matter, doesn't really feel anything,
and so those different kinds of matter have different kinds
of oscillles, like one grand one is pulling in one way,
the other one is pushing the other way, because it interacts.
And we can see patterns in the cosmic microwave background
radiation that reflects the oscillations of the plasma, and those
oscillations are sensitive to like how much matter was there

(38:15):
that was interacting, how much matter was it that was
not interacting, And that tells us how much dark matter
there was a bit jillion years ago. And to me,
like revealing that crazy, complicated, subtle fact about the early
universe from looking at like the wiggles in this tiny
little bit of light that nobody even knew about until
fifty years ago. It blew my mind when I when

(38:36):
I thought, like, wow, people are really dig in details
out of this thing. Do you remember where you were
or what you were doing when you had that thought.
That was earlier this morning when I googled cosmic microwave
background the agent no. UM. I came to astrophysics and
cosmology sort of late because my background was more in
particle physics and understanding, you know, the basic building structure

(38:57):
and basic building blocks. But I was always interested in
the universe, and so I did a little bit of
self teaching after I got tenure, did a little bit
more reading and try to understand this stuff. So about
ten years ago, I think that I really started to
try to wrap my mind around what is this stuff
out there in the universe? What is uh? What are
we learning about the origins of the universe from the
light that we can see here on Earth. So you

(39:17):
mentioned the CMB being able to give us clues about
dark matter behavior. Is that sort of one of the
new areas of research for the CMB, or you know,
what what are the hot topics now? If there's a
gold Russian data for you know, CMB related research, what
questions should I be putting on my grant application? Yeah?

(39:40):
That's great, Um. I think the most important question that
the CMB can answer is sort of like the pie
chart of the universe, like, what is most of the
energy in the universe used for? And we know roughly
the answer. It's five percent matter. Dark matter a huge
chunk of his dark energy. And the cool thing is
that we know that from you know, looking at matter

(40:01):
and looking at stars and looking at galaxy and seeing
the expansion of the universe. But the CMB gives is
a totally independent way to measure those fractions because again
sort of the oscillations in the plasma are sensitive to
those fractions. So what people are doing now is trying
to just get more precise measurements and asking does that
agree with what we already think. And the way you
get more precise measurements you just get more data because
you're looking for really small variations. So we have these

(40:24):
successive generations. First the telescope in the sixty four that
just heard like, oh it's there. Then there was a
satellite called Kobe in the nineties that found these variations.
They were like, oh, look this interesting information. Then there
was w MAP, which is a satellite saw even more details,
and then recently the Plank experiment. And so if you
look at the CNB over years, it's sort of like
this blob that's becoming more and more and sharper and

(40:46):
sharper focus and answering these questions in more detail, and
recently we're sort of getting slightly different answers, like the
CMB tells us this is this much dark energy in
the universe, whereas other measurements tell us a slightly different answer.
We don't know why those things don't agree. Is it
because our model the universe is wrong or because one
of these measurements is wrong? And so that's sort of

(41:07):
the current puzzles, like how let's make these two kinds
of measurements as precise as possible and see if they
agree and if they don't, Oh, that's a fun clue
because it tells us we're going to learn something. So
how do I interact with the cosmic microwave background every day?
Or do I is there any way for me to
see it? Or is it a way for it to

(41:28):
influence my life that I just might not be aware of. Well,
because there are microwaves, they hit your body and they
heat you up very slightly, right, it's not a huge
amount of radiation, but you can see if you have
one of those old television screens that a cathode ray tube,
not like a flat panel display. Those things are sensitive
to the microwave background, and part of the fuzz on

(41:48):
those screens comes from this background radiation. Really, and the
snow on those screens comes from this microwave background radiation.
So you could literally see this evidence years and years
and years ago. So I don't need a radio telescope,
I just need an old TV and I can I
can see it. That's right, you can see the secrets
of the early universe. That's a really great TV show. Amazing. Yeah,

(42:12):
And I think another thing that people are often confused
by sort of again this like where was it? And
I think the thing to remember is that it was everywhere.
And so the CNB they were seeing in one direction
was hot plasma that was in one place, and the
stuff we're seeing another direction was hot plasma we're seeing
from somewhere else. So I know in academia there's often
multiple schools of thought about really important things, theories, hypotheses, etcetera.

(42:36):
And it sounds like the detection of these radio waves
this microwave um background helped to resolve one of those disagreements.
Has it caused others do people not believe in it?
Or are there heated debates happening in the whole hallowed

(42:57):
halls of the Ivory Tower about the CMB. I think
it's a sort of a process, like a lot of
the old question has been put to rest. I don't
think anybody seriously disagrees with the Big Bang theory anymore.
But of course there are new questions, and some of
those new questions are about like what do we see
in the CMB. There are some weird things we don't understand,
and those lead to like crazy ideas. For example, there's

(43:20):
one spot in the CNB that's colder than all the
other spots. It's called the cold spot. What a great name.
And it's also kind of big. And you can say, well,
you know, there's random fluctuations. You would expect, some cold
and some hot, but this one is colder than you
would expect and bigger than you expect. So it's it's
kind of unusual. And anytime you see something a little
out of the ordinary, you wonder, is that a clue

(43:40):
or is that, you know, just random. And so people
speculated things like maybe that cold spot is evidence that
our universe when it was really young, bumped into another
universe and left basically a bruise. I know that's hard
to imagine, it's hard to even think about. But some
people have this theory that there are multiple universes created

(44:00):
one sort of in a multiverse theory, and if those
universes were near enough each other, they could have interacted
very early on, and they predict exactly this kind of
signature in the CMB as evidence for that. Now is
that a prediction or is this sort of a post addiction,
Like Okay, I saw this weird thing and now I'm
gonna try to explain it, and I get to make

(44:20):
this crazy theory. I don't know, but that's the kind
of thing people argue about. So still TBD, watch it,
watch this space. That's right, there's a lot left to
learn about the universe from the cosmic microwave background. How
should I be thinking about this? Like when I'm having
my you know, shower thoughts are so important. I think.
You know, when you're idly at rest doing a mundane

(44:41):
task that your brain doesn't have to think about, it
wanders off and usually for me into like existential questions.
That's when you think about physics. Physics, Yeah, more more philosophy. UM,
you know those big questions like why why are we here?
Is this seven am call I'm getting ready for? Really
that important in the grand scheme of things, like on

(45:03):
a universal time scale? You know, does anything matter? Should
I just be watching a Netflix marathon all day to day?
These types of things. So as I'm having those thoughts,
deep deep thoughts, how should I be thinking about the
cosmic microwave background? Is it um fossil as you said before,
because that sounds very static, but it's something that's continuing

(45:24):
to move and continuing to give information. Is it a
comforting um wrap of radiation from the early universe that's
giving me a hug? How should I? How should I
think about this? UM? I think you should think about
it aspirationally. You should wonder what else is out there?
What other information is floating out there in space. It's

(45:46):
going to give us some incredible deep knowledge about the universe.
It's going to change the entire context of our lives.
And we don't even know it exists yet, and then
in a hundred years or fifty years or two years,
somebody will discover it reveal something deep about the universe,
and we will have not even known. Um, I like
to look at the history of physics that way and

(46:06):
be like people stumble across something and it changes the
way we think about the universe. And I hope that
there are so I said aspirationally, because I hope there
are more of these. I hope there are more moments
when we dig up something from the early universe and
it teaches us something and maybe it's surprising, and people
are trying to do that right now. The plasma from
the early universe ended about four hundred thousand years after

(46:27):
the Big Bang, and that this is the only light
we can see because before that all the light was
just reabsorbed by the plasma, so it's sort of gone.
But people are trying to dig deeper, just saying, well,
what about like neutrinos from before from inside of that plasma,
because they don't interact very much, and maybe we could
see them were gravitational waves from the very first moment.
So we're trying to open up new kinds of eyes
to see deeper and deeper into the history of the

(46:48):
universe and answer our questions about that. So, um, yeah,
I think about that. I think about what your children
or their children will know about the universe that we
can't even imagine. So I'm like, I'm in justest imagining
the situation in which the people that ask questions and
want to know things are kind of like this nerve center.
And we have so many different senses like you and
I would have site and and sound, but we have

(47:10):
all of these different detectors that scientists have have developed
as as part of their senses. And so what I'm
hearing you say is that we're going to continue to
develop more senses as we want to be able to
detect the information around us. Is that accurate science is
making esp real. We are developing new senses to experience
the university you already here. First, guys, the universe was

(47:33):
in a state in which this type of radiation wasn't
able to escape, and then there was a cooling event
in which, uh, the universe became transparent, allowing light to
emanate through it. And this radiation is part of that
early expansion, and it's coming from all of these different

(47:56):
directions because we're expanding our idea of the Big Bang
beyond the point theory um, and so it's radiating from
everywhere because we are the center of the universe. Obviously
we're humans. It's meeting here on Earth right where we
are standing in the world and able to give us
information about the past experiences that that it had and

(48:17):
helping us understand the universe. That's right. But aliens somewhere else,
they're also seeing a CMB. They see a slightly different
map because the light that's getting to them left from
a different place, but the same way, they see different
stars in the sky than than we do. They're seeing
a slightly different CNB, So everyone would see everyone, all
of the different extraterrestrials in our universe is seeing a

(48:39):
different one and studying it differently. And maybe one day
we'll be able to put our data together and I
get the most accurate picture of what started all of this.
That's right, So I hope we do one day get
to talk to alien physicists. I have a lot of
questions for them about how the universe works and how
they think about it, and whether we're UM studying objective
truth or just based on our human bias and and

(49:02):
uh on our senses. I think they probably have all
sorts of other ways to observe the universe. We can't
even imagine UM. But I hope that they're impressed with
what we've accomplished and that we can learn from them. So,
the universe began, and had it begun slightly differently, we
wouldn't be here, but it developed the way that it did,
and so we're able to ask questions about how it

(49:22):
all started. That's right. So the amazing thing about the
Cosmic Microwave Background Edition is that it's all around us
and it gives us clues about the very beginning of
the universe, and hopefully one day we'll find more clues
and learn even more about the origins of our very existence.
And it's heating me the way that I heat soup.
That's my gutso made my big tang out for this.

(49:43):
That's right. It's exciting you. It's exciting you the way
you're microwave excitor soup. And I hope this podcast is
excited our listeners. I hope so too. So thanks Crystal
very much for joining me today. Oh thank you for
having me. This was a great conversation. And for those
of you out there, if you still have questions about
this topic, send them to us to questions at Daniel
and Jorge dot com. We really do answer all of

(50:03):
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have a question after listening to all these explanations, please
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You can find us at Facebook, Twitter, and Instagram at
Daniel and Jorge That's One Word, or email us at

(50:26):
Feedback at Daniel and Jorge dot com. Thanks for listening,
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