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How was the cosmic microwave background discovered? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, do you know what I don't understand about
0:11
Speaker 1: winning a Physics Nobel Prize? Oh yeah, what's that? Well,
0:14
Speaker 1: you know, to be honest, some of them seem kind
0:16
Speaker 1: of easy in hindsight, be easy to win a Nobel Prize. Yeah,
0:20
Speaker 1: I mean, like for Einstein, all he had to do
0:22
Speaker 1: is analyze someone else's experiment. It was just one idea
0:25
Speaker 1: that he had one day and boom, Nobel Prize. I
0:28
Speaker 1: guess that's easy if you're Einstein. Well, I mean also,
0:31
Speaker 1: like the discovery of X rays was totally by accident
0:35
Speaker 1: and it took about one day of work for them.
0:37
Speaker 1: That's true if you happen to have X rays around,
0:40
Speaker 1: or like the Higgs boson. You know, like college physics
0:43
Speaker 1: major can do that kind of math. All right, you win.
0:45
Speaker 1: I admitted getting a Physics Nobel Prize is easy, So
0:48
Speaker 1: then why don't we have one? Because we haven't tried.
0:52
Speaker 1: It's win one today, Daniel. Alright, great idea, Einstein, let's
0:54
Speaker 1: do it. Hi. I am more hammy cartoonists and the
1:11
Speaker 1: creator of PhD comics. Hi. I'm Daniel. I'm a particle
1:15
Speaker 1: physicist and I have not yet won a Nobel Prize.
1:17
Speaker 1: But maybe any day someday will be the day. Do
1:21
Speaker 1: you wake up every day thinking, maybe today's to day
1:24
Speaker 1: I'll have my great idea. I don't expect it to
1:26
Speaker 1: ever happen, but I do love those stories when somebody
1:29
Speaker 1: has a moment of insight or stumbles across something weird,
1:33
Speaker 1: and that morning when they woke up and had their
1:35
Speaker 1: oatmeal or whatever, they had no idea that it would
1:37
Speaker 1: be that fateful day. Maybe that's the key. It's the oatmeal.
1:40
Speaker 1: And maybe it's a special kind of oatmeal. Daniel like
1:43
Speaker 1: a radioactive oatmeal. Bitten by his radioactive oatmeal, he gained
1:47
Speaker 1: his proportional intelligence. There you go. Maybe that was a
1:51
Speaker 1: nice secret. I think when people say you're as smart
1:53
Speaker 1: as a bowl of oatmeal, they don't mean it as
1:55
Speaker 1: a compliment. Well, I think that's very disparaging of oatmeal,
1:58
Speaker 1: because you never know, there could be sentient genius oatmeal
2:02
Speaker 1: out there in space. They could be our next alien overlords.
2:06
Speaker 1: Yet another sci fi pitch for Netflix put it on
2:08
Speaker 1: the list. All right, Well, welcome to our podcast Daniel
2:10
Speaker 1: and Jorge Explain the Universe, a production of I Heart
2:13
Speaker 1: Radio in which we try not to turn your brain
2:16
Speaker 1: into oatmeal as we talk about all the amazing things
2:19
Speaker 1: that are out there in our universe, all the things
2:22
Speaker 1: that we have painstakingly uncovered in our search to reveal
2:26
Speaker 1: the fundamental nature of matter and radiation and everything in
2:30
Speaker 1: the universe, and all the things that science is still
2:33
Speaker 1: picking at, all the big questions that are out there,
2:36
Speaker 1: all the discoveries that might be far into the future
2:39
Speaker 1: or just around the corner. That's right. The universe is
2:42
Speaker 1: full of mysteries, full of big questions and wonderful discoveries
2:46
Speaker 1: just waiting for us to find them and possibly get
2:50
Speaker 1: a Nobel price for finding them in the congratulatory bowl
2:53
Speaker 1: of oatmeal. And sometimes the answer to those questions is
2:56
Speaker 1: already out there. It's beaming down at us from the cosmos,
3:00
Speaker 1: or it's in somebody's data. They just don't even recognize it.
3:04
Speaker 1: And sometimes those Nobel prizes come just from putting one
3:08
Speaker 1: thing next to the other, from finding that the answer
3:11
Speaker 1: to a question is already out there. Yeah, because technically
3:14
Speaker 1: all of the secrets of the universe, all of the
3:16
Speaker 1: great big truth about it, are out there for us
3:20
Speaker 1: to discover. I mean, it's not like they don't exist.
3:22
Speaker 1: They're there, which is haven't seen them or having discovered
3:24
Speaker 1: them or having known where to look. Yeah, you know,
3:27
Speaker 1: that's a really fun question, Like is it actually possible
3:30
Speaker 1: to unravel the nature of the universe without ever leaving
3:33
Speaker 1: the Earth? Just by watching this guy's It's sort of
3:36
Speaker 1: incredible what we have been able to figure out about
3:39
Speaker 1: like far flung corners of the universe, the way galaxies
3:43
Speaker 1: expand and collide and do all sorts of crazy stuff
3:45
Speaker 1: without ever having left the Earth. But I wonder if
3:48
Speaker 1: it's possible to actually figure out like all of it,
3:51
Speaker 1: to get all the way down to string theory and
3:53
Speaker 1: quantum gravity without ever going anywhere else. It would be
3:57
Speaker 1: pretty cool if all that information was beaming down on
4:00
Speaker 1: us right now. Are you saying, like, are we maybe
4:02
Speaker 1: in the wrong place, Like if we were somewhere else,
4:04
Speaker 1: we could see the secrets of the universe, you know,
4:07
Speaker 1: Or maybe they're all in one box but in another
4:10
Speaker 1: part of the galaxy. Yeah. Or it might be that
4:12
Speaker 1: you need to do some kind of experiment like smash
4:14
Speaker 1: black holes together at very high speeds in order to
4:17
Speaker 1: get the answer to some question. Or might be that
4:20
Speaker 1: you need to be able to look inside a black hole,
4:22
Speaker 1: which we can do from here. Maybe you need to
4:24
Speaker 1: be nearby it in order to decrypt the quantum information
4:28
Speaker 1: in the Hawking radiation. It might not be possible to
4:30
Speaker 1: gather all that information from Earth. Or maybe it is.
4:34
Speaker 1: Maybe if somebody was smart enough, they could figure out
4:36
Speaker 1: all the secrets of the universe and just from the
4:38
Speaker 1: data we are getting today. Yeah, hopefully not by getting
4:41
Speaker 1: us near a black hole or by smashing a couple
4:43
Speaker 1: of black holes together here on Earth. That's hounds kind
4:46
Speaker 1: of dangerous. Anything in the name of science not worth
4:49
Speaker 1: a noble prize. Well, you know, everybody makes their own
4:51
Speaker 1: judgment call on that. Please, physicists, check with the rest
4:54
Speaker 1: of us before you make those kinds of judgment calls.
4:56
Speaker 1: I know this is important for you, all of you,
4:59
Speaker 1: but you know, we might I'd have other priorities, your
5:01
Speaker 1: priorities to get to name the black hole machine, right,
5:04
Speaker 1: I want to be alive to me and to call
5:06
Speaker 1: it that, you know. But yeah, the history of physics
5:10
Speaker 1: and science here on Earth has a long and interesting history,
5:13
Speaker 1: full of amazing discoveries. And some of them happened kind
5:16
Speaker 1: of by accident, right, Oh, lots of them happened by accident.
5:19
Speaker 1: People stumble across stuff they didn't even know to look for,
5:22
Speaker 1: see things they don't understand, and only later realize that
5:25
Speaker 1: they contain secrets of the universe. So today we'll be
5:28
Speaker 1: covering one such story of an amazing discovery that really
5:32
Speaker 1: kind of illuminated in a very real way the beginning
5:36
Speaker 1: of the universe. Absolutely, it's some of the oldest light
5:39
Speaker 1: in the universe, and it tells us a lot about
5:41
Speaker 1: how the universe began and how hot and dense and
5:44
Speaker 1: crazy it was billions and billions of years ago, and
5:47
Speaker 1: it was almost overlooked and mistaken for pigeon poop. Wow,
5:53
Speaker 1: that is a big oops there for the physicist. So
5:56
Speaker 1: today on the program, we'll be talking about how was
6:03
Speaker 1: the cosmic microwave background discovered? Now, Daniel, this is the
6:08
Speaker 1: famous CNB, right, this is the famous CNB that has
6:11
Speaker 1: taught us so much about the nature of the universe.
6:14
Speaker 1: It's not the CNB R as they call it in
6:17
Speaker 1: the Marvel universe. You have a problem with that, Well,
6:19
Speaker 1: the scientists in the Marvel universe can call their CNB
6:22
Speaker 1: whatever they like, but out here in the real universe,
6:25
Speaker 1: we tend to call it the CMB. Just the cosmic
6:28
Speaker 1: microwave background, meaning like it's the background basically of the universe.
6:32
Speaker 1: It's everywhere, It's all around us. Photons from the early
6:35
Speaker 1: universe plasma are zooming all over the universe in every direction,
6:39
Speaker 1: no matter where you look. That's what we mean by background.
6:42
Speaker 1: It's sort of just like always, there's everywhere. Yeah, And
6:45
Speaker 1: it has a long and interesting history of people thinking
6:48
Speaker 1: it was there but not seeing it, or seeing it
6:50
Speaker 1: and not thinking it was there. It's kind of an
6:52
Speaker 1: interesting and dramatic plotline, right absolutely. And it's the kind
6:56
Speaker 1: of thing that could have been discovered very easily decade
7:00
Speaker 1: before it was, and in fact, it was discovered several
7:03
Speaker 1: times without even being understood, and so it's sort of
7:06
Speaker 1: like a story of missed opportunities and the folks who
7:09
Speaker 1: ended up winning the Nobel Prize for finding it could
7:12
Speaker 1: very easily not have So it sounds like a pretty
7:15
Speaker 1: intriguing story. So we'll dig into that and go over
7:18
Speaker 1: every detail. But at first we were curious about how
7:21
Speaker 1: many people know how this amazing discovery was found. So,
7:24
Speaker 1: as usual, Daniel went out there into the wilds of
7:26
Speaker 1: the Internet and asked people if they knew how the
7:29
Speaker 1: cosmic microwave background was discovered. And so if you would
7:33
Speaker 1: like to be interrogated about physics by a physicist without
7:36
Speaker 1: the opportunity to consult any reference materials that sounds fun
7:40
Speaker 1: to you, then please email me two questions at Daniel
7:43
Speaker 1: and Jorge dot com. Here's what people had to say.
7:45
Speaker 1: I think it was around the seventies. Whenever it was,
7:48
Speaker 1: they feel was a very powerful telescope maybe radio telescope
7:52
Speaker 1: to look at something else, and then they heard or thought, so,
7:56
Speaker 1: I'm like what they thought was noise from a local source.
8:00
Speaker 1: They even thought it was the pigeons that were nesting
8:01
Speaker 1: in the telescope and actually had a big job clearing
8:04
Speaker 1: that out, trying to get rid of it, but no
8:05
Speaker 1: matter what they did, couldn't get rid of it. And
8:07
Speaker 1: that but obviously eventually they realized it wasn't local at all,
8:10
Speaker 1: but from fort almost fourteen billion light years away. The
8:14
Speaker 1: NBA two words Hubble telescope. Okay, that's a tool, not
8:19
Speaker 1: an answer. Aliens told us about it, and they also
8:22
Speaker 1: told us where to look. So we pointed the Hubble
8:24
Speaker 1: telescope at the cosmic magawave background radiation and that's how
8:28
Speaker 1: we discovered it. I haven't really heard about it, just
8:32
Speaker 1: as an assumption, maybe e when we were trying to
8:36
Speaker 1: respond some kind of radiations. I think the background radiation
8:41
Speaker 1: was discovered by accident. Hadn't had nothing to do with
8:44
Speaker 1: someone using their microwave up and to make eggs. But
8:47
Speaker 1: I think it was World War Two. Weren't they doing
8:49
Speaker 1: radar experiments and they discovered this noise? But I think
8:54
Speaker 1: it was by accident. The cosmic microwave background was discovered
8:57
Speaker 1: by two scientists working at Bell Labs in New Jersey
9:01
Speaker 1: who were investigating a strange buzz they picked up when
9:05
Speaker 1: actually working on something else. I think it was discovered
9:08
Speaker 1: around nineteen sixties as one of the first discoveries of
9:12
Speaker 1: radio astronomy. After making sure it wasn't the error in
9:15
Speaker 1: data or in measurements, there was a lot of theorizing
9:19
Speaker 1: what did what it means and why the signal was
9:22
Speaker 1: actually hurt quite possibly with a radio telescope. Maybe astronomers
9:27
Speaker 1: or scientists were looking at like certain stars or something
9:30
Speaker 1: they're like, hey, these guys are given off a lot
9:32
Speaker 1: of radiation, and then they looked at the stars and
9:35
Speaker 1: they're like, oh, it's not the stars. Put something around it.
9:38
Speaker 1: But there's nothing around it, so they're like, oh, what
9:40
Speaker 1: if we just focused on the space around it? And
9:43
Speaker 1: then they focused on the space. All right, A lot
9:46
Speaker 1: of versions of the story here from the public. A
9:49
Speaker 1: lot of people seem to know something about how it
9:51
Speaker 1: was discovered by accident. Yeah, including apparently aliens told us
9:54
Speaker 1: about it. I like, how this president, you said two
9:57
Speaker 1: words hubble telescope bam drops to my and aliens. Oh,
10:01
Speaker 1: by the way, also aliens, well, how else do you
10:03
Speaker 1: know where the point your hubble telescope? Right? The aliens
10:06
Speaker 1: have to tell you it makes perfect sense. It's pretty
10:08
Speaker 1: surprising how many people hadn't heard about this. And also
10:12
Speaker 1: I knew a little bit about it. You know, generally
10:14
Speaker 1: people seem to know that it wasn't like this intentional thing,
10:17
Speaker 1: like there was some element of accident to it. That's
10:20
Speaker 1: exactly right. And it took a long time for people
10:22
Speaker 1: to even know that it should be there and know
10:25
Speaker 1: that we might be able to see it. So there's
10:27
Speaker 1: sort of like progress and back steps and forward steps
10:31
Speaker 1: on the theoretical side as well as on the actual
10:34
Speaker 1: like observational side. All right, well, let's get into this
10:37
Speaker 1: story then, and maybe take us back Daniel, because I
10:40
Speaker 1: imagine this story starts in the early nineteen hundreds, and
10:43
Speaker 1: you know, we were sort of just starting to discover
10:46
Speaker 1: how big the universe was and that it maybe came
10:49
Speaker 1: from a big bang. You know, what were we thinking
10:51
Speaker 1: at the time, and what did we know? Because you know,
10:54
Speaker 1: I imagine that the idea that there's some background noise
10:57
Speaker 1: in the universe is not that surprise think to think about,
11:00
Speaker 1: but it having some special meaning maybe is Yeah, so
11:04
Speaker 1: that we have to go back to basically Hubble. Hubble
11:07
Speaker 1: is the one who figured out that the universe was expanding.
11:10
Speaker 1: Before that, people thought that everything was just sort of
11:12
Speaker 1: like hanging out in space. Things hadn't changed in hundreds
11:16
Speaker 1: or thousands or billions of years. But Hubble discovered that
11:18
Speaker 1: there were other galaxies out there and that they were
11:21
Speaker 1: moving away from us faster and faster, and suddenly that
11:24
Speaker 1: made the universe dynamic instead of static, like things were
11:27
Speaker 1: definitely changing. And people had two totally different concepts of
11:32
Speaker 1: ways to explain what Hubble saw that the universe was expanding.
11:36
Speaker 1: One is the idea that's very familiar to us that
11:39
Speaker 1: if the universe is expanding, then you run the clock
11:41
Speaker 1: backwards in time, then it must have been more dense,
11:44
Speaker 1: must have been more compact, must have been more squeezed
11:47
Speaker 1: together in the beginning, and you can sort of track
11:49
Speaker 1: it back to a very early moment when you reach
11:51
Speaker 1: like infinite density, the singularity. So this is the big
11:55
Speaker 1: bang idea that the universe came from some like huge
11:58
Speaker 1: early expansion, and what we're now is the remnants of that,
12:01
Speaker 1: the continued expansion of the universe. So that was one idea,
12:04
Speaker 1: this big bang idea, right, because we we saw the
12:07
Speaker 1: stars and the galaxies right now, they're all moving away
12:10
Speaker 1: from us. So you know, the ideas that if you
12:13
Speaker 1: rewind then at some point everything was crunched together. Yeah,
12:16
Speaker 1: but some people didn't like that idea. They thought that's
12:19
Speaker 1: ridiculous for the universe to have a beginning and for
12:21
Speaker 1: it to begin in some sort of big bang. And
12:24
Speaker 1: in fact, the name big bang came about as a
12:26
Speaker 1: sort of like an insult, and they were like trying to,
12:28
Speaker 1: you know, make that idea sounds silly by calling it
12:31
Speaker 1: a big bang, and instead they preferred a steady state
12:34
Speaker 1: theory of the universe. That's sort of hard to have
12:37
Speaker 1: a steady state idea of the universe, that the universe
12:40
Speaker 1: like isn't changing on the largest scale. When you see
12:43
Speaker 1: that it's expanding, you know, how could that possibly be
12:46
Speaker 1: If things are expanding, don't they get less and less dense. Well,
12:49
Speaker 1: their idea was that there was some like source of
12:52
Speaker 1: new stuff in the universe, that stuff was constantly being created,
12:55
Speaker 1: and that was like refilling the universe. So the universe
12:59
Speaker 1: was expanding but at a constant density because there was
13:01
Speaker 1: some like thing that was like topping it off all
13:04
Speaker 1: the time. That is sort of what we think of now,
13:06
Speaker 1: but back then it seems sort of counter to the evidence. Well,
13:10
Speaker 1: that's interesting that you say that you're right that we
13:12
Speaker 1: know that the universe is expanding and that there is
13:15
Speaker 1: more space being created, but the universe is getting more
13:19
Speaker 1: and more dilute. The steady state theory involved like the
13:21
Speaker 1: creation of more stars and galaxies and more stuff in
13:24
Speaker 1: the universe to keep like the density constant. So the
13:27
Speaker 1: steady state theory was like, well, let's figure out how
13:30
Speaker 1: to make the universe so it's not getting more and
13:32
Speaker 1: more dilute, that it's always been this way and live forever.
13:35
Speaker 1: They were thinking, like, the density of the universe doesn't
13:38
Speaker 1: change it's somehow expanding, but the density is not changing. Yeah,
13:41
Speaker 1: because somebody's like pouring more syrup onto these pancakes all
13:45
Speaker 1: the time, and so even though it's dribbling off the edges,
13:48
Speaker 1: you're keeping the same amount of syrupe on top of
13:50
Speaker 1: your pancakes. That's my big pancake theory of the universe.
13:55
Speaker 1: I think you messed up that analogy. I think it's
13:57
Speaker 1: it's more like the pancakes getting bigger, and so somebody
13:59
Speaker 1: must be for more sarapes. There you go, all right there,
14:02
Speaker 1: all right, right, that's a more delicious, very breakfast theme
14:05
Speaker 1: physics analogy today. The oatmeal pancakes. It's the most important
14:10
Speaker 1: physics meal the day. Wait till you hear about my
14:12
Speaker 1: waffle based observation ideas, and might have to be another episode, Daniel,
14:16
Speaker 1: I'm stuffed already. And so these were some of the
14:18
Speaker 1: ideas people were bouncing around, like what does the expansion
14:21
Speaker 1: of the universe mean? Did it come from some early, hot,
14:23
Speaker 1: dense point or is there someplace where the universe is
14:27
Speaker 1: creating new stuff so that things don't get less and
14:30
Speaker 1: less dense as time goes on. I guess why were
14:32
Speaker 1: they fighting this idea of a more you know, kind
14:35
Speaker 1: of empty universe, like why couldn't the universe beginning more
14:38
Speaker 1: and more dilute. I think they didn't like the idea
14:41
Speaker 1: of a beginning. It seems sort of counterintuitive. They prefer
14:44
Speaker 1: the concept It seemed more natural to them to imagine
14:47
Speaker 1: the universe had always been here, because if there's a beginning, then,
14:50
Speaker 1: as you know, there are big questions about that beginning,
14:53
Speaker 1: what came before and what caused it? Why do we
14:55
Speaker 1: have a beginning? You can avoid some of those things
14:58
Speaker 1: if you imagine the universe is just always been this way.
15:00
Speaker 1: Like if you don't accept that the universe could have
15:03
Speaker 1: a beginning, then you have to make something up, like
15:05
Speaker 1: where is all this syrup coming from? Yeah, there are
15:07
Speaker 1: always more questions, but you know, it was sort of
15:09
Speaker 1: an aesthetic preference, and so you had physicists on both
15:12
Speaker 1: sides of the issue, some arguing that the universe must
15:14
Speaker 1: have started with a big bang and others suggesting that,
15:17
Speaker 1: you know, stuff was constantly being made in this steady state,
15:20
Speaker 1: and so that's what people were thinking about. They were like,
15:23
Speaker 1: where does the stuff in the universe come from? And
15:25
Speaker 1: they were trying to understand for example, where heavy stuff
15:28
Speaker 1: in the universe came from, Like, where does all the iron,
15:31
Speaker 1: where does all the nickel and all that stuff in
15:33
Speaker 1: the universe come from? Was it made during the Big Bang?
15:36
Speaker 1: Or is it somehow made somewhere else and being like
15:39
Speaker 1: poured into the universe somehow? I see, because it could
15:42
Speaker 1: have been made in the Big Bang, right, like the
15:43
Speaker 1: heavier elements could have been forged in that hot, tense
15:47
Speaker 1: initial moments. That's what people thought in the early part
15:49
Speaker 1: of the century that maybe in that incredible heat from
15:53
Speaker 1: the Big Bang, you could have made iron, and you
15:55
Speaker 1: could have made silicon and oxygen, and maybe all the
15:58
Speaker 1: elements were fused in that initial time period. So people
16:01
Speaker 1: spent a lot of time doing theoretical calculations of how
16:04
Speaker 1: hot it was back then in the very early universe,
16:07
Speaker 1: What was the temperature, what was the density? Were there
16:09
Speaker 1: the conditions needed to make all of the heavy elements.
16:13
Speaker 1: So that was the reason they started doing these calculations,
16:15
Speaker 1: and they realized, Wow, in the very early universe, there
16:18
Speaker 1: must have been this very very hot plasma, and that
16:21
Speaker 1: plasma must have glowed the way plasma from the Sun,
16:23
Speaker 1: for example, glows, And then the universe cooled, and at
16:27
Speaker 1: some point that plasma becomes transparent because all of the
16:30
Speaker 1: ions and it capture electrons as they cool and they
16:33
Speaker 1: become neutral, and then it's transparent. So what they were
16:35
Speaker 1: wondering about was all that energy, all that light that
16:38
Speaker 1: was now flying around the universe. Was there enough light
16:40
Speaker 1: there to like make the heavy elements? And they did
16:43
Speaker 1: a bunch of calculations and they decided, no, it wasn't possible.
16:47
Speaker 1: And now, of course we know that those heavy elements
16:49
Speaker 1: were not made during the Big Bang. The Big Bang
16:51
Speaker 1: mostly made hydrogen and helium and very tiny amounts of
16:55
Speaker 1: heavier things. The heavier elements were made later in stars,
16:58
Speaker 1: but they didn't know that at the time until they
17:00
Speaker 1: did these calculations. But how did they know that? You
17:02
Speaker 1: couldn't have made the heavier elements because there just aren't
17:05
Speaker 1: the conditions, Like you can't make iron, for example, under
17:08
Speaker 1: the conditions just after the Big Bang, like it needs
17:11
Speaker 1: to be hotter and denser. You need the conditions inside stars.
17:14
Speaker 1: But wasn't the Big Bang infinitely dance and super duper hot.
17:18
Speaker 1: It was, but not for very long, you know, And
17:20
Speaker 1: so like it took time for the basic particles to form.
17:23
Speaker 1: You needed like quarks to shake out of it, and
17:25
Speaker 1: then those quirks to get bound into protons, and then
17:28
Speaker 1: those protons to find electrons and that's basically all that happened,
17:31
Speaker 1: and then things cooled down. There was very very quick
17:33
Speaker 1: early expansion. Remember the Big Bang itself is an expansion
17:37
Speaker 1: that lasts like ten of the minus thirty seconds. I see.
17:40
Speaker 1: There wasn't enough time to make the heavier elements, is
17:43
Speaker 1: what you're saying. But just enough time to only make
17:45
Speaker 1: hydrogen and helium, just enough to time to make hydrogen
17:48
Speaker 1: and helium exactly and little trace elements of what comes next.
17:51
Speaker 1: And so the other elements were later made in stars.
17:54
Speaker 1: And this is where cosmologists kind of lost interest. They
17:57
Speaker 1: were like, all right, so there must have been this
17:59
Speaker 1: hot play and it must have generated a bunch of light,
18:02
Speaker 1: but we're not interested anymore because that couldn't have made
18:05
Speaker 1: the heavy elements. That was the question they were asking.
18:08
Speaker 1: So they had the idea that there might be this
18:10
Speaker 1: light from the early universe flying around, but they didn't
18:14
Speaker 1: care because it didn't answer the question they were asking
18:16
Speaker 1: At the time. They were more interested in, like had
18:19
Speaker 1: the planets come about and had its stars and galaxies,
18:22
Speaker 1: like the stuff that you can actually kind of that
18:25
Speaker 1: is interesting to them, at least at the time in
18:27
Speaker 1: the universe. Yeah, so it's very much motivated by like
18:30
Speaker 1: what questions scientists are asking. Sometimes you stumble across an
18:33
Speaker 1: idea and you don't realize, oh, this could actually be
18:35
Speaker 1: really interesting and important for a totally different question. They
18:39
Speaker 1: were focused on, you know, how do you make these
18:40
Speaker 1: heavy elements? And on top of that, nobody imagined that
18:43
Speaker 1: you could even see this light. Even if they thought,
18:46
Speaker 1: well that light is cool and if you could see it,
18:49
Speaker 1: it would prove that there was this hot, dense state
18:51
Speaker 1: in the early universe. They didn't imagine to be possible
18:54
Speaker 1: to see it today, and so they just sort of
18:56
Speaker 1: like wrote it off and cosmologists sort of like moved on.
18:59
Speaker 1: This is acculation is done in the forties by some
19:01
Speaker 1: guys named Alpha and Herman and George Gammao, and they
19:05
Speaker 1: did it, and people thought, well, I guess you can't
19:07
Speaker 1: make heavy elements in the Big Bang, and then they
19:09
Speaker 1: just sort of turned to other stuff. They thought the
19:11
Speaker 1: Big Band was too boring. They're like, you know, like
19:14
Speaker 1: all right, yeah, that's where the universe came from. It
19:17
Speaker 1: was a big flash, but nothing interesting happened, nothing interesting
19:21
Speaker 1: that we could see today. These photons, they started out
19:24
Speaker 1: really hot, you know, like thousands of degrees kelvin, but
19:26
Speaker 1: then they got cooled down as the universe expanded. They
19:29
Speaker 1: got stretched out as the universe expands down to very
19:32
Speaker 1: very cold temperatures, which means long wavelength, which means radio waves.
19:37
Speaker 1: And so at the time, radio astronomy was like really
19:41
Speaker 1: a brand new field that had just begun a few
19:43
Speaker 1: years earlier. So nobody imagined you could actually detect these
19:46
Speaker 1: faint signals. Nobody even bothered to propose that somebody do that.
19:50
Speaker 1: All right, well let's get into a little bit more
19:52
Speaker 1: detail about what they were expecting to see and then
19:55
Speaker 1: how it was accidentally discovered. But first let's take a
19:59
Speaker 1: quick break. Alright, we're talking about the cosmic microwave background
20:15
Speaker 1: and how it was discovered. Now, Daniel, some of our
20:17
Speaker 1: listeners might not know exactly what the cosmic microwave background
20:21
Speaker 1: is or where it comes from. You want to go
20:22
Speaker 1: as a quick recap of what it is and what
20:25
Speaker 1: exactly it is that we're seeing when we look at it. So,
20:27
Speaker 1: the cosmic backgrounwave background are photons from about three hundred
20:31
Speaker 1: eighty thousand years after the Big Bang. Right, big Bang happens,
20:35
Speaker 1: things are really hot and dense and stuck together, and
20:38
Speaker 1: the universe expands, which means everything is getting more dilute
20:41
Speaker 1: and more cool. And by about almost four hundred thousand years,
20:44
Speaker 1: the universe had cool to the point where atoms could form,
20:47
Speaker 1: like electrons were slow enough that they can now be
20:50
Speaker 1: captured by protons and turned into hydrogen, for example. And
20:53
Speaker 1: that means that the universe became transparent. So there's this
20:56
Speaker 1: moment when the universe goes from like really hot and
20:59
Speaker 1: glowy but opaque too, slightly less hot and slightly less
21:04
Speaker 1: glowy and transparent. Right, it becomes like glass all of
21:07
Speaker 1: a sudden. So what happens to those photons that were
21:09
Speaker 1: made just before the universe became transparent, Well, they were
21:13
Speaker 1: flying around and they're still flying around, and fourteen billion
21:17
Speaker 1: years later, most of them are still flying around. And
21:20
Speaker 1: so they were everywhere because the Big Bang was everywhere,
21:24
Speaker 1: and this plasma filled the entire universe and filled it
21:27
Speaker 1: with these photons. So that means that everywhere, all around
21:30
Speaker 1: us are these photons not from the Big Bang, itself,
21:33
Speaker 1: but from this hot plasma that existed about four hundred
21:36
Speaker 1: thousand years after the Big Bang. Yeah, I'm thinking like,
21:39
Speaker 1: it's like you're in the middle of a giant fire
21:41
Speaker 1: and then suddenly the fire, everything are all around you
21:45
Speaker 1: becomes transparent, and so you sort of get that one
21:49
Speaker 1: last you know, flash of light from that fire right
21:52
Speaker 1: before the universe became kind of solid. And because it
21:55
Speaker 1: happened everywhere all at once, then there are always photons
21:59
Speaker 1: wherever you look. Right, we look out and we see
22:02
Speaker 1: this just in the night sky. Right, if you point
22:04
Speaker 1: to a radio telescope to the night sky in any direction,
22:07
Speaker 1: you see this because there's always a place where fourteen
22:11
Speaker 1: billion years ago, almost a photon was created and it
22:14
Speaker 1: has been flying towards us ever since. And as time
22:17
Speaker 1: goes on, we're seeing these photons from further and further
22:20
Speaker 1: slices of that early plasma. So we're always seeing it.
22:24
Speaker 1: We always will see it. And so you were saying
22:26
Speaker 1: that in the beginning of the Nine DS and through
22:29
Speaker 1: the middle of it, we sort of knew this story.
22:32
Speaker 1: We knew that's what had happened or possibly happened at
22:34
Speaker 1: the Big Bang, and what happened to all those all
22:37
Speaker 1: that light. But you're saying, nobody really cared about seeing
22:39
Speaker 1: this light. Nobody imagined that you could write. Nobody thought, wow,
22:43
Speaker 1: you could actually go and detect this stuff. It seemed
22:45
Speaker 1: like it would be a really faint signal and you
22:47
Speaker 1: need really impressive technology. And so people just sort of like, well,
22:50
Speaker 1: I guess that existed, just like lots of other things
22:53
Speaker 1: probably existed in early states of the universe. Doesn't mean
22:56
Speaker 1: we think we can see clues of them now. It's
22:59
Speaker 1: sort of like incredib able to imagine that you could
23:01
Speaker 1: see today remnants of something that happened fourteen billion years ago, right,
23:06
Speaker 1: that's sort of incredible. Most of the stuff that happened
23:09
Speaker 1: a long time ago was gone, right, Like you can't
23:11
Speaker 1: see most of the dinosaurs that were on Earth, just
23:13
Speaker 1: a very few that happened to get fossilized. I think
23:16
Speaker 1: part of it is that, you know, we were at
23:18
Speaker 1: that time stuck on like visible light astronomy, right, We're
23:21
Speaker 1: trying to look at the entire universe only through like
23:23
Speaker 1: the visible lights spectrum. Yeah, at the same time, people
23:26
Speaker 1: were just starting to figure out that there were other
23:29
Speaker 1: ways to look at the universe. It was in the
23:31
Speaker 1: thirties that radio astronomy was accidentally invented because somebody built
23:35
Speaker 1: a big antenna to try to communicate across the Atlantic
23:39
Speaker 1: and realized, oh my gosh, there are crazy radio signals
23:42
Speaker 1: coming from space. What wise space making radio signals. And
23:46
Speaker 1: that was the discovery, for example, of the big radio
23:49
Speaker 1: source at the center of our galaxy, which turns out
23:52
Speaker 1: to be from a black hole's accretion disk. And so
23:54
Speaker 1: we had just begun to understand that radio astronomy was
23:57
Speaker 1: a possible thing. You could do another way to look
24:00
Speaker 1: at the universe. Right, everything in the university is glowing.
24:03
Speaker 1: Everything that interacts electromagnetically gives off some kind of light,
24:07
Speaker 1: and it just depends on the temperature. So you're not
24:10
Speaker 1: very hot, so you don't glow in the visible light
24:13
Speaker 1: the way like a white hot piece of metal does,
24:15
Speaker 1: or the sun does. You and the Earth do, however,
24:18
Speaker 1: glow in the infrared. And so if you're cold enough,
24:22
Speaker 1: then you glow at longer and longer temperatures which are
24:24
Speaker 1: not visible. So if you look at the night sky
24:26
Speaker 1: or any sky really and look at it in the
24:29
Speaker 1: frequency of radio waves, then you can see colder stuff,
24:32
Speaker 1: stuff that doesn't glow in the visible things like gas
24:34
Speaker 1: and dust and planets and other kinds of things. So
24:37
Speaker 1: it's a different way of looking at the universe. A
24:39
Speaker 1: different filter shows you different stuff, right, And it also
24:42
Speaker 1: travels differently through space, right, which is why it's sort
24:44
Speaker 1: of like clearer to see things in the radio spectrum.
24:48
Speaker 1: Longer wavelengths are less obstructed by like small particles and stuff,
24:52
Speaker 1: so radio can travel more easily through like big clouds
24:55
Speaker 1: of gas and dust and this kind of stuff. So
24:57
Speaker 1: let's you see through different things, because every odd is
25:00
Speaker 1: transparent or opaque at different frequencies. Right. For example, your
25:04
Speaker 1: walls are transparent in X ray, right, but opaque invisible light.
25:09
Speaker 1: You can see through them with some kinds of light
25:11
Speaker 1: X ray light with very high frequency, but you can't
25:14
Speaker 1: see through them in other kinds of light, like visible light.
25:17
Speaker 1: So that's kind of the picture that sets up the discovery.
25:20
Speaker 1: So we knew there was this light out there where
25:22
Speaker 1: we didn't think we could see it, and also we
25:24
Speaker 1: were just discovering, you know, the radio spectrum of signals
25:27
Speaker 1: out there in space. So then how did they finally
25:30
Speaker 1: put the two together? So people put the two together
25:32
Speaker 1: sort of accidentally at first, and it wasn't even realized
25:35
Speaker 1: until decades and decades later, because it was World War
25:39
Speaker 1: Two that really improved our radio technology. Obviously that was
25:43
Speaker 1: important for signaling during the war, and so it gave
25:45
Speaker 1: a great boost to like a lot of our electronics
25:48
Speaker 1: and radar and radio technology. And so after World War Two,
25:51
Speaker 1: people started playing around with radio a little bit more,
25:54
Speaker 1: and there were folks that were like looking at the
25:56
Speaker 1: sky and surveying it at various wavelengths. And for example,
26:00
Speaker 1: a Frenchman named Emil LaRue in ninety five made a
26:04
Speaker 1: measurement of radiation from the sky and he found this
26:08
Speaker 1: source of radiation at just the right frequency, which we
26:11
Speaker 1: now understand was the CMB. He just didn't understand what
26:15
Speaker 1: it was, and nobody recognized it. I see. He just
26:17
Speaker 1: hooked it up and he heard like a or something
26:20
Speaker 1: through his earphones or something. Yeah. And people are looking
26:23
Speaker 1: for sources right there, like pointing this telescope and various things,
26:26
Speaker 1: trying to find things that generated radio waves, like the
26:29
Speaker 1: center of the galaxy generated radio waves, the Sun generates
26:33
Speaker 1: radio waves, Jupiter. You're looking for like objects. You're trying
26:36
Speaker 1: to understand what's out there. But what they were seeing was,
26:39
Speaker 1: in addition this noise that you hear from every direction, right,
26:42
Speaker 1: it doesn't matter where you point at the center of
26:44
Speaker 1: the galaxy, of the center the Solar system, doesn't matter where.
26:47
Speaker 1: It's coming from every direction, and so that's sort of weird.
26:50
Speaker 1: And people had sort of forgotten this prediction by the
26:54
Speaker 1: theorists that there would be this like radio noise from
26:58
Speaker 1: the early universe out there, and then they started to
27:00
Speaker 1: hear it, and they didn't understand what it was. I see,
27:03
Speaker 1: But I guess how did they know it wasn't just
27:05
Speaker 1: noise like just general noisy equipment, you know, thermal fluctuations,
27:11
Speaker 1: you know, noise in the air. How did they know
27:14
Speaker 1: it was something special and not just like, hey, I
27:16
Speaker 1: have bad equipment. Yeah, that's a great question. That took
27:19
Speaker 1: a more detailed comparison between what was expected and what
27:23
Speaker 1: was predicted and what was actually seen. But we'll get
27:26
Speaker 1: there at a moment. To me, it's super fun to
27:27
Speaker 1: look back into history and see evidence of future discoveries
27:31
Speaker 1: in people's data, to see people who could have claimed
27:34
Speaker 1: the discovery of something which later won the Nobel Prize,
27:37
Speaker 1: they just didn't understand what they had and so this
27:39
Speaker 1: actually happened twice for the CMB. In nine was a
27:43
Speaker 1: meal LaRue and two years later a Russian guy named
27:47
Speaker 1: Shamanov observed a signal at the same temperature in every
27:50
Speaker 1: direction and didn't understand it, and they just sort of
27:53
Speaker 1: like went and then moved on and never really figured
27:55
Speaker 1: it out. Now, of course we know that was all
27:58
Speaker 1: the data they needed to claim this every of the CMB,
28:01
Speaker 1: they just didn't really have the context for it. Yeah,
28:04
Speaker 1: I mean, like, is it directional this noise or is
28:06
Speaker 1: it only coming from space? If I pointed back towards
28:09
Speaker 1: the Earth, I don't hear it, you know. I guess
28:11
Speaker 1: paint us a picture like if I'm in the sixties
28:13
Speaker 1: and I haven't SENTTENNA, what would I be experiencing? Yeah,
28:17
Speaker 1: so it comes from space, right. Earth actually is a
28:20
Speaker 1: big source of radio noise, so not just electronics, but
28:23
Speaker 1: like everything around us is constantly emitting light. Just like
28:27
Speaker 1: we said earlier, it's glowing, and so you've got to
28:29
Speaker 1: get rid of that by only pointing your antenna up
28:32
Speaker 1: at the sky, so you're listening to radio from the
28:35
Speaker 1: sky only. The interesting thing about this is that there
28:38
Speaker 1: doesn't seem to be any particular source of it. It
28:41
Speaker 1: doesn't seem like it's coming from the center of the galaxy,
28:43
Speaker 1: doesn't seem like it's coming from Jupiter or from the
28:46
Speaker 1: Sun or any particular source. Once you point your radio
28:49
Speaker 1: telescope up at the sky and listen, you see it
28:51
Speaker 1: equally from every direction, which is really weird. And it's
28:55
Speaker 1: a clue that's not coming from any particular object out there.
28:59
Speaker 1: It's just sort of like the cosmos are filled with
29:02
Speaker 1: this bath. And of course you have to make sure
29:04
Speaker 1: it's not instrumental, that it's not just like noise in
29:07
Speaker 1: your electronics or something like that. And so you can
29:10
Speaker 1: spend a lot of time trying to find that noise
29:13
Speaker 1: and remove it and make sure you know that's not
29:15
Speaker 1: from your electronics. But you can tell that it's not
29:18
Speaker 1: from any particular object because it's coming from every direction
29:21
Speaker 1: in the sky. It was definitely coming from somewhere, is
29:23
Speaker 1: what you're saying. It was coming from space, right, It
29:26
Speaker 1: was definitely not coming from Earth, all right, So then
29:28
Speaker 1: what was the big breakthroughout it they piece it all together.
29:31
Speaker 1: It was in the sixties when one group at Princeton
29:35
Speaker 1: realized a whole lot of second we might be able
29:37
Speaker 1: to see this radiation. They sort of like dug back
29:40
Speaker 1: into these old calculations from the forties to think about
29:44
Speaker 1: this light from their early universe and realize that with
29:47
Speaker 1: the advance in radio technology, it might actually be possible.
29:51
Speaker 1: And so this is like go back and read old
29:53
Speaker 1: papers people, because there are great ideas out there that
29:56
Speaker 1: people wrote down that they didn't follow up on because
29:58
Speaker 1: the technology wasn't there. And so there was a guy
30:00
Speaker 1: Princeton named Dickie who realized, you know what, we could
30:03
Speaker 1: probably see this light. We think it's out there. It
30:06
Speaker 1: would be evidence that the universe was wasn't hot and
30:09
Speaker 1: dense enough to generate this light. And now we think
30:12
Speaker 1: we might be able to see it. So let's go
30:14
Speaker 1: build a radio telescope so we can go and look
30:17
Speaker 1: for it. So this was Dickie at Princeton. I see.
30:19
Speaker 1: It was somebody who said, like, hey, radio astronomy is
30:22
Speaker 1: a thing. You could find interesting signals out there in
30:25
Speaker 1: the radio spectrum, and oh, by the way, um you
30:27
Speaker 1: should be able to see this early light, this dim
30:30
Speaker 1: light from the universe beginning. Yeah, and it was a
30:32
Speaker 1: great idea, you know, the technology had come around. The
30:35
Speaker 1: question was interesting, I realized, Wow, I have the hammer
30:39
Speaker 1: to bang in this nail. And actually, as a weird acide,
30:43
Speaker 1: Dickie didn't believe in the Big Bang as the beginning
30:46
Speaker 1: of the universe. He didn't think the universe had a beginning,
30:49
Speaker 1: but he did think that the universe had an early,
30:52
Speaker 1: really hot, dense state. He had this other idea. He
30:56
Speaker 1: thought of the universe as a sort of a cycle.
30:58
Speaker 1: He thought the universe expanded and then slow down and
31:00
Speaker 1: crunched back together again, and he was trying to understand
31:03
Speaker 1: if that crunch was sort of like intense enough to
31:06
Speaker 1: break apart all of the matter. He wanted to find
31:09
Speaker 1: this early radiation as like evidence of how matter was
31:12
Speaker 1: destroyed rather than created. He thought this fireball destroyed the
31:17
Speaker 1: previous universe and then hours was birthed out of that
31:20
Speaker 1: what like a crunch from the Big Bang or before
31:23
Speaker 1: the Big Bang, from before the Big Bang. He thought
31:26
Speaker 1: that our universe was just like the latest and infinite
31:29
Speaker 1: series of universes, and that before our big bang, there
31:33
Speaker 1: was a big crunch, and that this sort of like
31:35
Speaker 1: cleansed the universe from all the stuff from the previous universe,
31:38
Speaker 1: you know, sort of like wipe the table and set
31:40
Speaker 1: this for a new meal. He's thinking, maybe you can
31:42
Speaker 1: hear the crunch or see like this crunching the current universe. Yeah,
31:46
Speaker 1: and he thought that maybe this cosmic microwave background radiation,
31:49
Speaker 1: if you could spot it, would be evidence for this
31:51
Speaker 1: like cleansing radiation that basically destroyed the previous universe and
31:55
Speaker 1: helped create ours I see. And what made them think
31:58
Speaker 1: that radio would be a better way to see it
32:00
Speaker 1: than other wavelengths. So they did this calculation. They thought
32:03
Speaker 1: how hot was it back then? And it was about
32:06
Speaker 1: three thousand degrees kelvin, And if that light was still around,
32:10
Speaker 1: what would be its wavelength now? So it's a little confusing.
32:13
Speaker 1: We talked about the temperature of light. What we really
32:16
Speaker 1: mean when we say the temperature of light is we
32:18
Speaker 1: mean the temperature of a thing which would generate light
32:22
Speaker 1: at a certain frequency. So, for example, we say the
32:25
Speaker 1: light was three thousand degrees kelvin, we really mean a
32:27
Speaker 1: plasma that was three thousand degrees kelvin would glow a
32:31
Speaker 1: certain frequency. Something that's colder, some that's three degrees kelvin,
32:34
Speaker 1: for example, would glow at a much longer frequency. But
32:38
Speaker 1: if you have a plasma for a long, long time ago,
32:41
Speaker 1: and the glowing at three thousand degrees kelvin. It made
32:43
Speaker 1: very high frequency light light that like zigs and zags
32:46
Speaker 1: really quickly. As the universe expands, member space stretches, that
32:51
Speaker 1: light gets too longer and longer frequencies. That light gets stretched.
32:54
Speaker 1: Doesn't get slowed down. Light always moves to the same speed,
32:57
Speaker 1: but the wavelengths gets stretched. So now that light is
33:00
Speaker 1: much longer frequency, whereas we say colder temperature. And so
33:05
Speaker 1: they did that calculation. They figured what the frequency of
33:08
Speaker 1: the light should be, and they figured it should be
33:10
Speaker 1: something corresponding to radiation from an object. They around three
33:14
Speaker 1: or five or ten degrees kelvin. So they sort of
33:16
Speaker 1: knew that if this light from the early universe glowed
33:20
Speaker 1: at a certain frequency or a frequency range, it's not
33:23
Speaker 1: like you can measure that glow in the X rays
33:25
Speaker 1: or in the visible light, like it only glows in
33:27
Speaker 1: that certain frequency. Yes, it would be characteristic at that temperature,
33:31
Speaker 1: all right, And so they were poison to go look
33:33
Speaker 1: for it basically and then realize what an amazing discovery
33:38
Speaker 1: it was. So let's get into how they found it
33:41
Speaker 1: and when they realized what they were sitting on. But first,
33:44
Speaker 1: let's take another quick rate. All right, we're talking about
33:58
Speaker 1: the cosmic microwave background and how it was discovered, and
34:03
Speaker 1: it feels like people knew was there and this new technology,
34:06
Speaker 1: this radio astronomy, was just coming into fashion, and so
34:11
Speaker 1: people were ready to see it. People were ready to
34:13
Speaker 1: see it, you know. But just like to recap the
34:15
Speaker 1: crazy history, it was like predicted in the forties and
34:18
Speaker 1: then ignored, accidentally discovered twice in the fifties and then ignored,
34:23
Speaker 1: and then in the early sixties, Dickie at Princeton is like,
34:25
Speaker 1: hold on a second, I bet we could see this.
34:28
Speaker 1: Let's build a telescope to look for it. So he's
34:30
Speaker 1: the first one to like really bring this idea together
34:33
Speaker 1: and decide to look for this thing on purpose. But
34:36
Speaker 1: he's not the one who actually found it. Oh really,
34:38
Speaker 1: But did he build a telescope for it to look
34:41
Speaker 1: for it? No, he got started and they were like
34:43
Speaker 1: getting going and starting to build this thing. Meanwhile, at
34:46
Speaker 1: the same time, totally coincidentally, sixty kilometers away from Princeton,
34:51
Speaker 1: at Bell Labs, there was another couple of guys working
34:54
Speaker 1: at a totally different project looking for something totally different.
34:58
Speaker 1: They built a radio telescope because they were working from
35:01
Speaker 1: Bell Labs and they were trying to communicate with balloons satellites.
35:04
Speaker 1: Bell Labs was experimenting with like building a telecommunication networks
35:08
Speaker 1: using floating balloons in the upper atmosphere. So they built
35:11
Speaker 1: this thing to talk to balloons. So they had already
35:15
Speaker 1: built one, but not to do astronomy. To do like communications,
35:18
Speaker 1: you had to do communications. And so they had built
35:20
Speaker 1: this thing and they were like trying to talk to balloons,
35:23
Speaker 1: and then Bell Labs decided, you know what, we're not
35:25
Speaker 1: interested in this. Let's cancel the whole project. We're not
35:28
Speaker 1: interested in like balloons satellites as a way to build
35:31
Speaker 1: the telecommunications network. But these guys Penzis and Wilson, the
35:34
Speaker 1: ones working from Bell Labs, they had done radio astronomy
35:37
Speaker 1: for their PhDs. They knew how to do that, and
35:40
Speaker 1: they were like, all right, well we have this awesome telescope.
35:43
Speaker 1: Why don't we point at the sky and see what
35:45
Speaker 1: we see. We got some questions about you know, they
35:48
Speaker 1: wanted to follow up from basically from their THESS and
35:50
Speaker 1: do some more research. So they just sort of like
35:52
Speaker 1: took advantage of this existing thing and started trying to
35:55
Speaker 1: do some research. I see. So they were originally scientists
35:58
Speaker 1: and they probably hoped they could use it for signs,
36:00
Speaker 1: but they had this pesky engineering problem they had to
36:04
Speaker 1: work on. But then when that got canceled, they could
36:06
Speaker 1: do signs on it. Yeah, And so they had this instrument. Now,
36:09
Speaker 1: Dickie was building one for himself over Princeton because he
36:12
Speaker 1: knew what to look for. Penz S and Wilson they
36:15
Speaker 1: already had it, but they didn't know what to look for.
36:17
Speaker 1: They weren't looking for the cosmic marcrotwave background. They didn't
36:20
Speaker 1: know what existed. It wasn't on their radar, so to speak,
36:22
Speaker 1: at all. They were just trying to build a sensitive
36:25
Speaker 1: instrument so they could listen to the sky. And you know,
36:27
Speaker 1: they're great engineers, and they built this really awesome telescope.
36:31
Speaker 1: If you look at pictures of it, it it looks kind
36:32
Speaker 1: of funny. It doesn't look like a telescope you see
36:35
Speaker 1: often because it's only part of a parabola. It looks
36:38
Speaker 1: sort of like a big shovel, like a big scoop,
36:40
Speaker 1: because it's only a little sliver of a parabola. Because
36:43
Speaker 1: they wanted to be really careful and only pointed towards
36:46
Speaker 1: the sky, so it's like really well shielded from the
36:48
Speaker 1: ground and just gathers a bit of the radio waves
36:51
Speaker 1: from the sky. Now did they set out to look
36:53
Speaker 1: for this cosmic microwave background or were they, you know,
36:56
Speaker 1: hoping to look at stars and black holes and things
36:59
Speaker 1: like that. They were not looking for this at all.
37:01
Speaker 1: They had no idea this thing existed as a concept,
37:04
Speaker 1: and they had no idea that it was possible to
37:06
Speaker 1: see it. One of them was interested in like finding
37:08
Speaker 1: big clouds of hydrogen that were glowing, so they wanted
37:11
Speaker 1: to look for other stuff. But they were really good
37:13
Speaker 1: engineers and builders, and so they built this thing, and
37:16
Speaker 1: they cooled it really really cold, because what you want
37:19
Speaker 1: to do for your radio telescope is not absorbed signals
37:22
Speaker 1: from like the telescope itself. Remember, everything glows, including your telescope.
37:27
Speaker 1: So they had to cool the whole telescope down to
37:29
Speaker 1: four point two degrees kelvin so they didn't like swamp
37:33
Speaker 1: itself with its own radio signals. And then finally in
37:35
Speaker 1: July nine, while Dickie is over there building his own telescope,
37:40
Speaker 1: they turn it on and what they saw was a
37:42
Speaker 1: lot more noise than they expected because they had done
37:46
Speaker 1: such a good job of like cooling everything that they
37:48
Speaker 1: expected to hear this clean signal. But really they saw
37:51
Speaker 1: this like giant hiss in the radio wave spectrum. Yeah,
37:54
Speaker 1: they saw this giant hiss, and they pointed their telescope
37:57
Speaker 1: in different directions. It's on a big wheel, so you
37:59
Speaker 1: could like turn it this way and that way in
38:01
Speaker 1: the other way, and they just couldn't get rid of
38:03
Speaker 1: this hiss. And they like took apart all their electronics
38:06
Speaker 1: and replaced them. They like put another layer of shielding
38:09
Speaker 1: on everything, They cooled everything down a little bit. All
38:11
Speaker 1: this made like a very small amount of difference, reducing
38:14
Speaker 1: the noise a very small amount. But they couldn't get
38:17
Speaker 1: rid of this hiss. I see. They were trying to
38:19
Speaker 1: get rid of the science signal, but they did because
38:22
Speaker 1: they didn't know it as a science signal. Yeah, exactly.
38:24
Speaker 1: They thought it was just noise that was going to
38:26
Speaker 1: interfere with their science. And at one point they found
38:29
Speaker 1: a bunch of pigeons that were nesting in their telescope,
38:32
Speaker 1: and they had covered part of the electronics with pigeon poop,
38:35
Speaker 1: or as they called it in their paper White Poultry
38:38
Speaker 1: Dialectic Material, and they cleaned all that off, but it
38:42
Speaker 1: didn't help anything, and so they were very disappointed. You know,
38:45
Speaker 1: at the time, Wilson says, this was a huge disappointment
38:48
Speaker 1: for us scientifically, And they spent like a year plunking
38:51
Speaker 1: away at this thing, trying to get rid of this noise.
38:54
Speaker 1: They had no idea what they were looking at. Well,
38:56
Speaker 1: in a way, they were right, you know, like if
38:58
Speaker 1: they were trying to get you know, radio waste, like
39:01
Speaker 1: those from a cloud of hydrogen somewhere, this is sort
39:03
Speaker 1: of noise that gets in the way, right, Like the
39:05
Speaker 1: universe just has this noise. They just didn't know it
39:08
Speaker 1: was a feature of the universe absolutely. You know, one
39:10
Speaker 1: man's noise is another woman's signal as another woman's Nobel prize.
39:14
Speaker 1: And we have that in particle physics. All the time
39:17
Speaker 1: we were looking for the top cork, and now the
39:19
Speaker 1: top cork is an obstacle in finding other particles. We
39:22
Speaker 1: wish we could like turn it off and get it
39:24
Speaker 1: out of the way so we could see other stuff.
39:26
Speaker 1: And so yeah, it's very subjective, all right. So then
39:28
Speaker 1: they thought they had some sort of error or some
39:31
Speaker 1: sort of equipment failure for over a year, and then
39:34
Speaker 1: how did they realize that this was something of interest?
39:37
Speaker 1: So Pensis, one of the guys who built this telescope,
39:40
Speaker 1: happened to run into one of his friends, Bernard Burkey,
39:43
Speaker 1: on an airplane, who told him that Dicky over Princeton
39:46
Speaker 1: was looking for this exact thing. So Pensis is like
39:48
Speaker 1: complaining about how we have this his in our telescope.
39:51
Speaker 1: Oh my gosh, we don't understand it. And he says,
39:53
Speaker 1: you should talk to these guys at Princeton because I
39:55
Speaker 1: think they know what you found. Oh wow, no kidding
39:58
Speaker 1: on an airplane, on an airplane, just like by chance.
40:01
Speaker 1: And I'm guessing this is, you know, the sixties, So
40:03
Speaker 1: they were, you know, we're in ties, drinking cocktails, smoking. Yeah,
40:08
Speaker 1: it sucking in the plane right over the loud propeller noises. Yeah.
40:13
Speaker 1: So Pensy has calls up Dickie at Princeton and says,
40:16
Speaker 1: I heard about this thing you're predicting. Dickie sends him
40:19
Speaker 1: a paper written by his student John Peebles, predicting this
40:22
Speaker 1: noise and explaining exactly what it should look like. And
40:25
Speaker 1: Pensys is like, wow, this is exactly what we are
40:28
Speaker 1: seeing in our telescope right now. They had no idea,
40:32
Speaker 1: you know, what does it mean? What it looks like?
40:33
Speaker 1: Should like it? Should it have a specific like signature
40:36
Speaker 1: and when you look at the signal in the frequency spectrum,
40:39
Speaker 1: or should it have this particular shape to it, or
40:41
Speaker 1: what is that like? How would you recognize it? Yeah,
40:43
Speaker 1: it looks like what we call black body radiation. So,
40:46
Speaker 1: as we said earlier, everything in the universe that has
40:49
Speaker 1: a temperature glows, and it glows at a specific frequency,
40:53
Speaker 1: but not at only one frequency. It tends to peek
40:55
Speaker 1: at a frequency and then have a particular shape. So
40:58
Speaker 1: at one frequency you'll have the high it's intensity of radiation,
41:01
Speaker 1: and then at the nearby frequencies it will sort of
41:03
Speaker 1: fall off in a very characteristic pattern that we call
41:06
Speaker 1: black body spectrum. And so what they saw was the
41:09
Speaker 1: frequency of something at two point seven degrees kelvin glowing
41:14
Speaker 1: with black body radiation. And so it wasn't just like
41:17
Speaker 1: we saw a bunch of photons of this one number,
41:19
Speaker 1: like they saw the whole shape. You know, it's like
41:21
Speaker 1: if you saw a mountain of a very specific shape
41:24
Speaker 1: and somebody predicted seeing a mountain of exactly that shape.
41:27
Speaker 1: You'd be like, okay, you've understood how that mountain came
41:30
Speaker 1: to be because black body radiation. I think it doesn't
41:33
Speaker 1: just look like a bell curve, like a random noise curved.
41:36
Speaker 1: It actually has kind of a shape twit, right, Yeah,
41:38
Speaker 1: it has a shape. It's asymmetric around the peak, so
41:40
Speaker 1: it's very characteristic. All right. So then Dicky's like, oh,
41:44
Speaker 1: like I'm building the cells coope, but these guys already
41:46
Speaker 1: have it and we've been scooped. Yeah, exactly. There's a
41:49
Speaker 1: famous story where Dicky gets off the phone from talking
41:52
Speaker 1: with Penzias and says, boys, we've been scooped. And that's
41:55
Speaker 1: really kind of a bummer for Dicky because he's the
41:57
Speaker 1: one who had this idea to look for it and
41:59
Speaker 1: started building his telescope, like that was really the ingenuity,
42:03
Speaker 1: and Penzias and Wilson just sort of like stumbled across it,
42:06
Speaker 1: had no idea what they had found until Dicky told
42:08
Speaker 1: them that's what you get for answering the phone, Daniel,
42:11
Speaker 1: That's why I never answered my phone. It could be
42:14
Speaker 1: somebody trying to scoop. So then they worked together. Everyone
42:20
Speaker 1: was a very good science citizen at that point, and
42:22
Speaker 1: Dickie like explained to them what they were looking for,
42:24
Speaker 1: and they all agreed to publish together. So Dicky and
42:27
Speaker 1: his crew published a paper saying, we predict that if
42:30
Speaker 1: you looked in the sky this frequency, you could see
42:33
Speaker 1: the afterglow of remnants from the Big Bang and it
42:36
Speaker 1: would look just like this, and you can do it
42:38
Speaker 1: and it'll be very interesting. And then in the same journal,
42:40
Speaker 1: the next paper is Penzias and Wilson saying, by the way,
42:44
Speaker 1: we've looked in the sky and we see this weird glow,
42:47
Speaker 1: we think it might be explained by this previous paper
42:49
Speaker 1: you just read by Dicky and his group. Interesting, it
42:51
Speaker 1: was a two part series. It was a two part series.
42:54
Speaker 1: And this is nice. You know when scientists who are
42:56
Speaker 1: working on something and realize they're sort of in competition
42:59
Speaker 1: or in working in parallel, they decided to publish together
43:02
Speaker 1: rather than like have some crazy race to who gets
43:05
Speaker 1: their paper in one minute before. Yeah, that's that's pretty cool.
43:08
Speaker 1: So then, because I guess Dickie didn't have his telescope ready,
43:11
Speaker 1: It's not like he could have just like jumped in
43:13
Speaker 1: and found the signal. He just still ways away from
43:16
Speaker 1: having a functioning telescope. Yeah, he had been scooped right,
43:19
Speaker 1: and just by chance, if Penzias and Wilson had waited
43:21
Speaker 1: another year or something, then Dickie could have had the
43:24
Speaker 1: idea and the data. But he didn't, And Penzias and
43:27
Speaker 1: Wilson went on to win the Nobel Prize in nineteen
43:30
Speaker 1: seventy eight for this observation. Wow, and also people's gut
43:34
Speaker 1: it to write peoples who originally had this idea and
43:36
Speaker 1: wrote the paper. He won the Nobel Prize in two
43:38
Speaker 1: thousand nineteen for like other contributions to cosmic microwave background theory.
43:44
Speaker 1: But Dickie in the end never won the Nobel Prize.
43:46
Speaker 1: I seem so back then it went to the people
43:49
Speaker 1: who have discovered it, not the people who predicted that
43:51
Speaker 1: it would be there. Yeah, because if you look back
43:53
Speaker 1: in history, it turns out that other people had already
43:56
Speaker 1: predicted it, right. People in the forties had the idea
43:59
Speaker 1: that this would be there, And there was this other
44:01
Speaker 1: Russian group which in the early sixties had also published
44:04
Speaker 1: a paper saying, by the way we might be able
44:06
Speaker 1: to see this, people should go look for it. So
44:08
Speaker 1: that was an idea which was sort of old hand
44:11
Speaker 1: bubbling up around the world at the same time, and
44:13
Speaker 1: maybe by a lot of those people who had died
44:16
Speaker 1: or something. Right that you couldn't give him the Nobel
44:18
Speaker 1: Prize for it, that's true. You can't give the Nobel
44:20
Speaker 1: Prize to somebody if they've already died. Yeah, alright, Well,
44:22
Speaker 1: so that's how we humans discovered the cosmic microwave background.
44:26
Speaker 1: And it's something that's pretty significant, right. It tells us
44:29
Speaker 1: a lot about the conditions for the early universe, about
44:33
Speaker 1: the composition of the universe. It confirms things like dark matter,
44:36
Speaker 1: dark energy. I mean, there's a lot in that signal. Yeah.
44:40
Speaker 1: Hawking says it's the greatest discovery of the century, if
44:43
Speaker 1: not of all time. And the reason is that it
44:47
Speaker 1: is really very, very rich, like how the cosmic microwave
44:51
Speaker 1: background looks, and specifically how it's not exactly smooth but
44:55
Speaker 1: has these little ripples in. It tells us a lot
44:57
Speaker 1: about how that early universe plasma was rating what it
45:00
Speaker 1: was doing, and like ripples in that plasma are sensitive
45:03
Speaker 1: to things like is the dark matter fraction of the
45:06
Speaker 1: universe or five, because it changes how that matters, sort
45:10
Speaker 1: of slashes back and forth if the dark matter is
45:13
Speaker 1: interacting or not. So, as you say, we can fit
45:15
Speaker 1: a lot of the parameters of the universe. A lot
45:17
Speaker 1: of the questions about what the universe is made out
45:19
Speaker 1: of and how it came to be come from understanding
45:22
Speaker 1: that in great detail. And you know, years later people
45:25
Speaker 1: launched a satellite to measure the cosmic microwave background radiation
45:28
Speaker 1: very precisely. That was called the Kobe satellite, and then
45:31
Speaker 1: that one a Nobel prize. So it's like a very
45:34
Speaker 1: rich area of research. Right. There's not just a lot
45:37
Speaker 1: of information in it, but it also kind of basically
45:40
Speaker 1: confirms our theories about the early universe, right, Like it
45:44
Speaker 1: it's like perfect evidence for all these series about the
45:46
Speaker 1: Big Bang and inflation and the you know what was
45:49
Speaker 1: happening in ing in those early few seconds. Yeah, it
45:52
Speaker 1: definitely confirms the Big Bang, right It tells us that
45:55
Speaker 1: the steady state theory just doesn't work because the universe
45:58
Speaker 1: was once much more dense and hot and crazy, so
46:01
Speaker 1: rules out the steady state theory and confirms the Big Bang.
46:04
Speaker 1: It doesn't exactly confirm inflation precisely. There are some predictions
46:08
Speaker 1: for like weird little wiggles in the CNB, we might
46:11
Speaker 1: be able to see that would confirm inflation. And several
46:14
Speaker 1: years ago there was an experiment called BICEP two that
46:16
Speaker 1: thought they had seen that, but it turns out they
46:18
Speaker 1: were wrong. But in the future, there's a lot more
46:20
Speaker 1: we can learn about the universe. Whether inflation was right,
46:23
Speaker 1: is it the right theory of what caused the Big
46:25
Speaker 1: Bang in the very very early universe, We still don't know,
46:28
Speaker 1: But we hope that there's more layers of information in
46:30
Speaker 1: the CNB that will one day reveal even more about
46:33
Speaker 1: the early universe and how it all came to be. Yeah,
46:35
Speaker 1: there might still be more noble prices in there. Yeah,
46:38
Speaker 1: there might be information in that data right now which
46:41
Speaker 1: you could download onto your laptop and if you knew
46:43
Speaker 1: how to interpret, could win you a Nobel prize. Sometimes
46:47
Speaker 1: everything you need is right in front of you, or
46:50
Speaker 1: I guess the dangerous you could download it, have it
46:52
Speaker 1: on your computer and then not discover something, and then
46:55
Speaker 1: in the future of some physicists and a podcast saying,
46:57
Speaker 1: see that person had that data in his or her
47:00
Speaker 1: laptop and didn't see so better to just just not downloaded
47:06
Speaker 1: or just don't you never hear about how you were scooped,
47:09
Speaker 1: you'll have an easier life, all right. Well, that is
47:12
Speaker 1: how we discover one of the greatest discoveries a few
47:15
Speaker 1: in history apparently, although I would argue that, you know,
47:17
Speaker 1: that bowl of oat meal I had this morning was
47:19
Speaker 1: pretty good discovering as well. I think brown sugar and
47:24
Speaker 1: oatmeal that was a pretty big discovery. No thanks, no thanks, huh,
47:29
Speaker 1: that's a level too far. Alright, that's for the future.
47:32
Speaker 1: All right. Well, we hope to enjoy that story. Thanks
47:34
Speaker 1: for joining us, See you next time. Thanks for listening,
47:44
Speaker 1: and remember that Daniel and Jorge Explain the Universe is
47:47
Speaker 1: a production of I Heart Radio or more podcast for
47:51
Speaker 1: my heart Radio, visit the I heart Radio app, Apple Podcasts,
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