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How Old Is The Universe? · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: Hey, Jorge, I've been meaning to ask you a really
• 0:09
  Speaker 1: important question. Yeah, go ahead, How old are you? How
• 0:12
  Speaker 1: old am I? That? Isn't that a rude question? It's
• 0:15
  Speaker 1: a little bit rude, but I want to mask it
• 0:17
  Speaker 1: by saying that I'm interested scientifically. I just want to know, like,
• 0:21
  Speaker 1: how did the Jorge begin? Did you start with a
• 0:23
  Speaker 1: big bang? Well, I'm not sure how my mom would
• 0:27
  Speaker 1: describe it. Am I getting better with age? Is that
• 0:30
  Speaker 1: kind of why you're asking? Yeah, it's Orge like a
• 0:32
  Speaker 1: fine wine that just gets better and better and more valuable,
• 0:35
  Speaker 1: or sort of like yesterday's banana. I have been working
• 0:38
  Speaker 1: on my earthly bouquet and under tones of cherry and oak.
• 0:44
  Speaker 1: I'll give you ninety points on the wine scale. Don't
• 0:48
  Speaker 1: you think we should focus on bigger topics? Perhaps? Yeah?
• 0:51
  Speaker 1: I think asking the age of stuff is a really
• 0:53
  Speaker 1: good way to figure out like where it came from
• 0:55
  Speaker 1: and why it's important and uh, and you know where
• 0:57
  Speaker 1: it's going to go and the whole context of every thing.
• 1:00
  Speaker 1: So yeah, I'm interested in how old you are, But
• 1:02
  Speaker 1: I'm also interested in how old the Earth is, or
• 1:05
  Speaker 1: how old the Solar system is, or how old the
• 1:07
  Speaker 1: galaxy is or even how old is like everything? You
• 1:11
  Speaker 1: want to be rude to everything. Yeah, I want to
• 1:15
  Speaker 1: ask your mom if she was around during the Big
• 1:17
  Speaker 1: Bang and so she can tell us all about it.
• 1:20
  Speaker 1: Your mom is so old she witnessed the Big Bang. Hey, look,
• 1:25
  Speaker 1: you're the one who brought your mom into this. Hi'm
• 1:42
  Speaker 1: Borning and I'm Daniel, and I'm about forty two years old.
• 1:46
  Speaker 1: Forty two years is the perfect age, actually, since that's
• 1:50
  Speaker 1: the answer to life, the universe and everything. Yeah, that's
• 1:54
  Speaker 1: why I brought it up, because you know, I'm the
• 1:57
  Speaker 1: answer to everything. They didn't notice you highly avoided staying
• 2:01
  Speaker 1: in your age. I thought I was doing. Did you
• 2:03
  Speaker 1: think that was sly? I just kind of avoid that,
• 2:05
  Speaker 1: didn't Yeah, and now that's double stubble sly. Oh my goodness,
• 2:12
  Speaker 1: can you can you go for a triple sly? Well,
• 2:14
  Speaker 1: let me tell you from the advanced age of forty
• 2:17
  Speaker 1: three that forty two is a good year. You should
• 2:19
  Speaker 1: enjoy yourself while you're young. You should go out there
• 2:22
  Speaker 1: and you know, enjoy your fitness and your your flexibility,
• 2:25
  Speaker 1: because when forty three comes around, everything changes, really peak life,
• 2:32
  Speaker 1: no jokes aside. For me, every year has been better
• 2:34
  Speaker 1: than the last so so far, forty three is the
• 2:36
  Speaker 1: best year I've ever had. Awesome? Oh what are we
• 2:39
  Speaker 1: talking about? This is our podcast Daniel and Jrnean explained
• 2:43
  Speaker 1: the universe. This is not just us chatting about random stuff.
• 2:46
  Speaker 1: This is our podcast where we try to explain the
• 2:48
  Speaker 1: whole universe to you, from front to back, from start
• 2:51
  Speaker 1: to finish. Today's topic how old is the universe? How
• 3:00
  Speaker 1: long has all of creation been around this amazing, beautiful, crazy,
• 3:05
  Speaker 1: chaotic mess that we find ourselves in. How long has
• 3:07
  Speaker 1: this party been going on? Are we at the beginning
• 3:10
  Speaker 1: of the party? Is a party ending? We're the best
• 3:13
  Speaker 1: moments of the party in the very early evening and
• 3:15
  Speaker 1: we've missed it already. Is the universe equivalent of forty two?
• 3:19
  Speaker 1: Or is it all downhill from here? That's right. Let's
• 3:22
  Speaker 1: hope that, like my life, every year in the universe
• 3:25
  Speaker 1: just gets better than the last. Right, that would be
• 3:27
  Speaker 1: pretty nice. Um, But I think it's a it's a
• 3:29
  Speaker 1: really important question. It's interesting not just from a you know,
• 3:32
  Speaker 1: academic physics point of view, like can we figure this out?
• 3:36
  Speaker 1: But I think it's one of these great questions that
• 3:38
  Speaker 1: touches on something. I think everybody wants to know the
• 3:40
  Speaker 1: answer to right, like how did it all start? And
• 3:43
  Speaker 1: where is it? Where is it going to go? Yeah,
• 3:44
  Speaker 1: it's pretty amazing to imagine not knowing how old you are.
• 3:48
  Speaker 1: Can you can you imagine not knowing how old you are?
• 3:51
  Speaker 1: That is kind of hard to imagine. I think actually
• 3:53
  Speaker 1: a lot of people in the world used to not
• 3:55
  Speaker 1: know like when they were born or how old they were,
• 3:58
  Speaker 1: and their parents were to tell them, oh, you were
• 3:59
  Speaker 1: born in the summer, it was several years ago. And
• 4:02
  Speaker 1: you know, I think a lot of people don't keep
• 4:03
  Speaker 1: track of their age. But you're right. For most modern people,
• 4:05
  Speaker 1: we know exactly how old we are, and that is
• 4:07
  Speaker 1: a big part of our identity. Yeah, I wonder if
• 4:10
  Speaker 1: you could figure it out, Like if you if I
• 4:11
  Speaker 1: went into your brain and erased that little bit of
• 4:14
  Speaker 1: neurons that store how old you are, if you could
• 4:17
  Speaker 1: piece it together just from your memories. I think if
• 4:20
  Speaker 1: you slice my brain open, yeah, you would find rings
• 4:22
  Speaker 1: and probably be able to count them and figure out
• 4:24
  Speaker 1: how old that was. Don't recommend doing that at home.
• 4:27
  Speaker 1: By the way, people said, where your old book comes from? Them? Yeah,
• 4:32
  Speaker 1: if I was a fine one, I think I would
• 4:33
  Speaker 1: be I would taste them sassy but unpretentious. Yeah, and
• 4:37
  Speaker 1: I'm a little nerdy, just a little bit of nerty,
• 4:40
  Speaker 1: just a little PhD in physics, nerdy but not not overpowering,
• 4:44
  Speaker 1: just enough in its undertones. Yeah, but yeah, I imagine
• 4:48
  Speaker 1: how disorienting it would be not to know how old
• 4:50
  Speaker 1: you are. Absolutely, I guess I'm trying to say. It's
• 4:53
  Speaker 1: that it's important to our identity to know how old
• 4:56
  Speaker 1: we are. Yeah, it is. And it's important identity to
• 4:58
  Speaker 1: know how old human civilization is, Like what is our history?
• 5:02
  Speaker 1: How long have people have been crawling along this planet?
• 5:04
  Speaker 1: How long have people been people? Right? That tells you, um,
• 5:08
  Speaker 1: you know of something about the context and of your
• 5:10
  Speaker 1: own life. And I think even more interesting is how
• 5:13
  Speaker 1: long our lives are compared to how long the world
• 5:17
  Speaker 1: has been around? You know, like we live a hundred years?
• 5:20
  Speaker 1: Is that long compared to the lifespan of the Earth
• 5:22
  Speaker 1: or in the universe? Is the universe two hundred years
• 5:25
  Speaker 1: old and I'm gonna live a hundred or is it
• 5:27
  Speaker 1: a tiny flicker in this vast, incredibly old universe? Right?
• 5:32
  Speaker 1: I think that helps us understand like whether we mean
• 5:34
  Speaker 1: anything spoiler, we don't yeah, kind of like where does
• 5:37
  Speaker 1: it Where do our lives fit in the history of
• 5:40
  Speaker 1: everything else? Yeah? And uh, even more interesting, I think
• 5:44
  Speaker 1: the unanswerable is not just a question of how long
• 5:47
  Speaker 1: are our lives compared to the history of the universe
• 5:50
  Speaker 1: so far, but how much history is left in the universe? Right?
• 5:53
  Speaker 1: Are we in the very, very beginning stages of the universe?
• 5:56
  Speaker 1: Is the universe of baby or is it middle age? Right?
• 5:58
  Speaker 1: We have a whole other podcast about that. So these
• 6:01
  Speaker 1: questions are important, I think. Yeah, I feel like we're
• 6:03
  Speaker 1: going through puberty right now, at least the United States.
• 6:06
  Speaker 1: Maybe your voice is already pretty low for going through puberty, Harry.
• 6:11
  Speaker 1: I'm not gonna ask you if you're growing hair in
• 6:12
  Speaker 1: any new places. I don't want to know. Is the
• 6:14
  Speaker 1: universe growing hair in new places? I hear that things
• 6:17
  Speaker 1: are pretty hairy in Mars. Black holes are growing hair.
• 6:20
  Speaker 1: People talk about hairy black holes these days. That's totally
• 6:23
  Speaker 1: a physics topic. Are black holes black haired or blonde? Well,
• 6:28
  Speaker 1: that's the question, is like, how many characteristics can a
• 6:31
  Speaker 1: black hole have? You know, because in the in the sense,
• 6:33
  Speaker 1: it's just a collection of matter compressed down to a
• 6:35
  Speaker 1: tiny scale. I know, black holes can rotate. We know
• 6:38
  Speaker 1: they have mass, and the question is, you know, basically,
• 6:41
  Speaker 1: can they have other attributes? You know? Okay, so this
• 6:43
  Speaker 1: is a really interesting and important question. How old is
• 6:46
  Speaker 1: the universe? And we were wondering how many people out
• 6:49
  Speaker 1: there know how old the universe is? Yeah, which is
• 6:52
  Speaker 1: interesting from two points of view. One is do people care?
• 6:55
  Speaker 1: How they spend any time thinking about it? Is it
• 6:57
  Speaker 1: important to people? And two, if they do care, do
• 7:01
  Speaker 1: they know the right answer or they operating under completely
• 7:03
  Speaker 1: false pretenses for how old kind of creation is? Yes, So,
• 7:07
  Speaker 1: as usual, Daniel went out there to his university and
• 7:10
  Speaker 1: asked the question how old do you think the universe is?
• 7:14
  Speaker 1: Here's what people had to say. I think thirteen billion years?
• 7:19
  Speaker 1: And do you know how we know that number? I
• 7:23
  Speaker 1: believe we look way out as far as we can
• 7:27
  Speaker 1: and detect the early gases from the universe, and then
• 7:30
  Speaker 1: we extrapolate based on the distance we're looking. I think
• 7:34
  Speaker 1: something like that fifty walk one years, fifty one years?
• 7:43
  Speaker 1: Oh wait, wait, world or inniversity, the universe, the university
• 7:48
  Speaker 1: and the universe to bill two billion? And do you
• 7:52
  Speaker 1: know how we know the age of the universe by
• 7:55
  Speaker 1: the Big Bang? Yeah, big, big theory and looking at
• 7:58
  Speaker 1: how far the stars are right two? Not the university,
• 8:04
  Speaker 1: the whole universe. Oh, I'm sorry, villain. All right, And
• 8:10
  Speaker 1: do you know how we know the age of the universe?
• 8:12
  Speaker 1: How do we measure it? Starts six billion years? Okay?
• 8:17
  Speaker 1: And you know how we measure the age of the universe.
• 8:19
  Speaker 1: I'm guessing it has to do with some type of
• 8:22
  Speaker 1: carbon dating materials that don't all right, cools, thanks, billion
• 8:27
  Speaker 1: years billions that your best guests older than twenty six
• 8:30
  Speaker 1: years old? And you know how we measure the age
• 8:33
  Speaker 1: of the universe and the idea or how would you
• 8:35
  Speaker 1: figure it out if you had to? I don't know,
• 8:37
  Speaker 1: grabbing ripples biologist, all right, thanks very much? All right,
• 8:43
  Speaker 1: pretty good. A lot of pretty good guesses, right, Yeah,
• 8:46
  Speaker 1: A lot of people guess sort of in the range
• 8:48
  Speaker 1: of billions of years, right, which is totally respectable. Um.
• 8:51
  Speaker 1: I think my favorite answers were the people who misunderstood
• 8:54
  Speaker 1: my question and they thought I was asking them how
• 8:56
  Speaker 1: old is the university and which it just turned fifty
• 8:59
  Speaker 1: at a big party, etcetera. But when they said fifty,
• 9:02
  Speaker 1: I didn't really understand that misunderstood. I thought for a
• 9:05
  Speaker 1: moment that they thought the universe was fifty years old,
• 9:08
  Speaker 1: and I thought, oh my god, I've met some really
• 9:11
  Speaker 1: young Earth creation is how do I respond, you know,
• 9:13
  Speaker 1: like to keep a straight face. I'm trying to be respectful,
• 9:16
  Speaker 1: you know. Um, and then I understood, oh no, they
• 9:18
  Speaker 1: just missed her mishearth question. Well, when you're young and
• 9:21
  Speaker 1: you're in college, the university is your universe in a way, right, Yeah, exactly,
• 9:26
  Speaker 1: that is the in their whole life. Um. I like
• 9:28
  Speaker 1: the guy who said, I don't know at least twenty
• 9:30
  Speaker 1: six years old, right, which is tells you a little
• 9:33
  Speaker 1: bit how self centered some college students are. But you know,
• 9:36
  Speaker 1: everybody gave it their shot. He's like, yeah, the universe
• 9:38
  Speaker 1: was here when I was born, so obviously at least
• 9:41
  Speaker 1: twenty six years old, that's right. And maybe that's the
• 9:43
  Speaker 1: only information that matters to that guy, you know, like,
• 9:45
  Speaker 1: who cares as long as it was around for me,
• 9:48
  Speaker 1: nothing else is important. Yeah, I guess his universe started
• 9:50
  Speaker 1: twenty six years ago. Yeah exactly. But you know he's
• 9:53
  Speaker 1: actually using a strategy to measure the universe which scientists use,
• 9:57
  Speaker 1: which is how old is stuff in the universe? The
• 10:00
  Speaker 1: universe has to be at least as old as that.
• 10:02
  Speaker 1: So while his you know, focus on himself, isn't that
• 10:05
  Speaker 1: helpful in determining the age of the actual universe. He's
• 10:08
  Speaker 1: got a good idea there about how to figure it out.
• 10:10
  Speaker 1: How old is the oldest thing that I know about?
• 10:13
  Speaker 1: That should give you give you at least like a
• 10:15
  Speaker 1: minimum age of the universe. Yeah, exactly, so he even
• 10:18
  Speaker 1: though he's a biologist, he sort of invented that strategy
• 10:20
  Speaker 1: on the fly. Well, I think it's important. Let's start,
• 10:24
  Speaker 1: first of all, talking about what it means to ask
• 10:27
  Speaker 1: how old the universe is? Like, what is the age?
• 10:30
  Speaker 1: What does the term the age of the universe mean? Yeah,
• 10:33
  Speaker 1: that's right, that's the kind of answer somebody would give it.
• 10:34
  Speaker 1: They're trying to evade a question, right, how old you Well,
• 10:37
  Speaker 1: what do you mean by age? I mean, do you
• 10:39
  Speaker 1: mean conception moment of birth? Right? Um. But there's actually
• 10:44
  Speaker 1: a really good analogy there, because human age is a
• 10:47
  Speaker 1: little fuzzy. Like if you're conceived on a certain day
• 10:49
  Speaker 1: and then you're born premature, you know you are older
• 10:53
  Speaker 1: than you otherwise would have been, right, Um. Whereas if
• 10:56
  Speaker 1: you stayed in your mother's womb longer, you're technically younger,
• 10:59
  Speaker 1: even though you know it doesn't really matter, which is
• 11:04
  Speaker 1: kind of arbitrary, right because technically you're body and your brain,
• 11:08
  Speaker 1: all your parts started earlier than your birth. Yeah, and
• 11:12
  Speaker 1: we're not taking a position here, and there's a fetus alive,
• 11:17
  Speaker 1: and maybe that's why, maybe that's why we do that.
• 11:19
  Speaker 1: But you know, actually I heard that in other cultures
• 11:21
  Speaker 1: they define age a little differently, like in someone like
• 11:24
  Speaker 1: in in the US, when you're born year zero, right,
• 11:27
  Speaker 1: and the clock starts then. But in other cultures, when
• 11:30
  Speaker 1: you're born, you're one, and your age increases in the
• 11:33
  Speaker 1: new year, and everybody goes up one year in the
• 11:36
  Speaker 1: new year, where the concept of age is like how
• 11:38
  Speaker 1: many years have you been around in not exactly how
• 11:42
  Speaker 1: many years since your moment of birth. Um, So the
• 11:45
  Speaker 1: age of the universe is sort of a similar question, right,
• 11:48
  Speaker 1: Like how do you define the zero with the moment
• 11:51
  Speaker 1: of the universe equals zero? T equals zero. Yeah, let's
• 11:59
  Speaker 1: let's by what it means tigal zero. So what what
• 12:02
  Speaker 1: I physicists mean usually when they say T equals zero, Well,
• 12:05
  Speaker 1: it's not terribly well defined, is the problem. What we
• 12:08
  Speaker 1: can do is we can say, we know when now is,
• 12:11
  Speaker 1: and we can walk backwards from now to what we
• 12:15
  Speaker 1: know to be a very hot and dense state in
• 12:17
  Speaker 1: the very early moments of the universe, right like a
• 12:20
  Speaker 1: big primordial hot plasma which is nasty and wet and
• 12:24
  Speaker 1: all sorts of stuff is happening right like a baby
• 12:27
  Speaker 1: when it's born, like a baby, exactly, a big hot,
• 12:29
  Speaker 1: nasty mess. It probably wasn't as loud, I don't know,
• 12:31
  Speaker 1: maybe it was. Actually there was very on acoustic oscillations,
• 12:34
  Speaker 1: so it could have been a lot of screaming going
• 12:36
  Speaker 1: on UM. And we understand that very well, like we
• 12:39
  Speaker 1: can propagate that forward to get to our universe, we
• 12:41
  Speaker 1: can go backwards. But the problem is that just before
• 12:44
  Speaker 1: that is very fuzzy for us, Like we can't see
• 12:47
  Speaker 1: past that. For those of you who heard our episode
• 12:49
  Speaker 1: about the baby universe, we can't see earlier than like
• 12:52
  Speaker 1: three eighty thousand years UM after the Big Bang, and
• 12:56
  Speaker 1: so we don't exactly know what happened then and so
• 12:59
  Speaker 1: exactly how to define it. It's not clear like you'd
• 13:02
  Speaker 1: like to say T equal zero is the big Bang? Right? Yeah?
• 13:06
  Speaker 1: Isn't that what they usually mean that the universe started
• 13:08
  Speaker 1: with the Big Bang or we don't know, right, except
• 13:11
  Speaker 1: that we don't really have a great definition of what
• 13:13
  Speaker 1: the Big Bang is, right, Like, we don't know what
• 13:15
  Speaker 1: was the Big Bang? Was it a singularity that then exploded? Um?
• 13:20
  Speaker 1: Was it you know, some weird quantum blob? Was it inflotons?
• 13:23
  Speaker 1: Like that? Whole process is still very mysterious to us.
• 13:26
  Speaker 1: So we don't know exactly what happened and exactly how
• 13:28
  Speaker 1: long it took, so we can do you just blew
• 13:31
  Speaker 1: my mind a little bit. Yeah, scientists think Tiko zero
• 13:35
  Speaker 1: is the moment possibly of the Big Band, but you're
• 13:37
  Speaker 1: saying it's possibly, Like we don't really know what happened
• 13:41
  Speaker 1: around the time of Tiko zero. Yeah, and the I mean,
• 13:44
  Speaker 1: the whole definition of the Big Bang is still a
• 13:46
  Speaker 1: kind of bit fuzzy, Like some people think the Big
• 13:48
  Speaker 1: Bang is sort of still happening. Like what was the
• 13:50
  Speaker 1: Big Bang? It was this inflation of a dense amount
• 13:54
  Speaker 1: of matter into a hot promodial gas that was on
• 13:57
  Speaker 1: a macroscopic scale, right, really fast inflation and took less
• 14:01
  Speaker 1: than ten to the minus thirty seconds, right, and that
• 14:03
  Speaker 1: ever since then, things have been expanding, But things are
• 14:06
  Speaker 1: still expanding and they're still inflating, like we have dark energy,
• 14:09
  Speaker 1: which is just like a modern day analogy of of inflation.
• 14:13
  Speaker 1: So from some point of view, you could say, like,
• 14:14
  Speaker 1: the Big Bang is still banging. So then when do
• 14:17
  Speaker 1: you put to equal zero from the beginning of the
• 14:19
  Speaker 1: Big Bang? Like, we don't really understand very well the
• 14:22
  Speaker 1: physics of what happened in the early days, so it's
• 14:23
  Speaker 1: hard to define what T equal zero is. So you mean,
• 14:26
  Speaker 1: we can look back in our history, and there you
• 14:29
  Speaker 1: get to a point where you can look beyond and
• 14:32
  Speaker 1: you just assume that there's some sort of event beyond that.
• 14:35
  Speaker 1: But we can't see that's right. You don't have records
• 14:37
  Speaker 1: of your of yourself beyond pictures of you when you
• 14:40
  Speaker 1: were one year old, Like you don't you have no
• 14:42
  Speaker 1: idea what you look like before you were one years
• 14:44
  Speaker 1: old exactly. And so what you can do is you
• 14:46
  Speaker 1: can extrapolate. You can say, like, well, I know how
• 14:48
  Speaker 1: it happened when I went from one to two and
• 14:50
  Speaker 1: two to three and three to four, and I understand
• 14:52
  Speaker 1: the biology of and so I can extrapolate backwards from
• 14:54
  Speaker 1: one and think about what zero must have been like
• 14:57
  Speaker 1: and when zero was right, how long it took to
• 14:59
  Speaker 1: get to one, which is really the question when you
• 15:01
  Speaker 1: when you were conceived probably yeah, exactly. But if you
• 15:05
  Speaker 1: suspect that the physics happening down there between zero and one,
• 15:09
  Speaker 1: you know, just after the moments of the Big Bang,
• 15:11
  Speaker 1: we're different, we're interesting, um or maybe not typical of
• 15:16
  Speaker 1: what happened the rest of your life, then there's a
• 15:17
  Speaker 1: lot of uncertainty how to do that extrapolation. You can't
• 15:20
  Speaker 1: just blindly extrapolate, like what if the physics before I
• 15:23
  Speaker 1: was one years old were totally different, which means I
• 15:26
  Speaker 1: could be older than one year old when I think
• 15:28
  Speaker 1: I'm one year old. Yeah exactly. And it's not that
• 15:30
  Speaker 1: we think the laws of physics were different, but you
• 15:33
  Speaker 1: don't just different stuff was happening. Stuff we haven't seen, stuff,
• 15:36
  Speaker 1: we haven't had a chance to understand, um stuff. So
• 15:39
  Speaker 1: you know, we're extrapolating down, down, down, down down. But
• 15:42
  Speaker 1: we get to a region where we have don't really
• 15:44
  Speaker 1: have a lot of data to extrapolate into, so we're
• 15:47
  Speaker 1: skeptical of that extrapolation. But this is a very technical
• 15:51
  Speaker 1: discussion of like exactly when ti equal zero is. The
• 15:54
  Speaker 1: good news is doesn't really matter. What do you mean,
• 15:57
  Speaker 1: it doesn't matter. We just talk about how important was.
• 16:01
  Speaker 1: It doesn't really matter exactly when you define to equal zero,
• 16:04
  Speaker 1: because this uncertainty is a small number compared to the
• 16:07
  Speaker 1: age of the universe. Like we can extrapolate all the
• 16:10
  Speaker 1: way from now back to you know, less than a
• 16:13
  Speaker 1: million years after the Big Bang whatever that was, right, um,
• 16:17
  Speaker 1: And so there's an uncertainty there of like you know,
• 16:19
  Speaker 1: a million years, a couple of million years whatever for
• 16:21
  Speaker 1: what happened before the part we can extrapolate beyond. But
• 16:25
  Speaker 1: that's a small fraction we think of the age of
• 16:27
  Speaker 1: the universe. So if you want to say how old
• 16:28
  Speaker 1: is the universe, you can sort of sweep that question
• 16:31
  Speaker 1: under the rug. You can say, well, you know, how
• 16:33
  Speaker 1: old is it? How far back can we see? And
• 16:36
  Speaker 1: that's really to the age of the universe. So if
• 16:39
  Speaker 1: I said, Daniel, I hear you're forty three years old
• 16:42
  Speaker 1: plus or minus a million years, you would just sweep
• 16:46
  Speaker 1: that under the rug. I would say, no, that's an
• 16:48
  Speaker 1: accurate statement or a correct statement. Oh that's right. Technically
• 16:53
  Speaker 1: you are yeah plus or minus a million yeah, more
• 16:57
  Speaker 1: plus than minus but um, yeah, exactly. But I think
• 17:00
  Speaker 1: a better analogy would be like, you know, I'm forty
• 17:02
  Speaker 1: three plus or minus a day, you know, or a second.
• 17:06
  Speaker 1: Right there, These are details on the scale of the
• 17:08
  Speaker 1: times we're talking about. But you know, we want our
• 17:11
  Speaker 1: listeners to really understand the nitty gritty, and so the
• 17:13
  Speaker 1: exact definition the age of the universe is a little
• 17:16
  Speaker 1: bit fuzzy because those first few fractions of a second
• 17:19
  Speaker 1: especially are not well understood. Okay, so when we say
• 17:23
  Speaker 1: the age of the universe, we really mean how old
• 17:26
  Speaker 1: the universe is since some mysterious thing happened called the
• 17:31
  Speaker 1: Big Bang. That's right, exactly, and even deeper, right, we
• 17:36
  Speaker 1: don't know what happened before that, So it's just an
• 17:38
  Speaker 1: arbitrary thing to call that t equal zero. Right. It
• 17:40
  Speaker 1: could have been that before the Big Bang there was
• 17:42
  Speaker 1: another universe which had like a big bang of its
• 17:45
  Speaker 1: own and a big crunch. It's not really a different universe.
• 17:48
  Speaker 1: It's just like part another cycle. And this could have
• 17:50
  Speaker 1: been happening forever. So when you talk about the age
• 17:53
  Speaker 1: of the universe, you really can only talk about the
• 17:55
  Speaker 1: age since this early state that we understand. What happened
• 17:59
  Speaker 1: before that is a little question mark, Like the universe
• 18:01
  Speaker 1: could have just started before that it could have gone
• 18:03
  Speaker 1: on forever before that. Okay, let's let's get into how
• 18:07
  Speaker 1: we know all this stuff, but first let's take a
• 18:09
  Speaker 1: quick break. Okay, Daniels, settle this for us. How old
• 18:25
  Speaker 1: do physicists think the universe is? Years old? I mean,
• 18:31
  Speaker 1: that's how long? So what else is important? Um? You know,
• 18:35
  Speaker 1: the most accurate age of the universe currently is thirteen
• 18:39
  Speaker 1: point eight billion years. That's how long we think the
• 18:42
  Speaker 1: universe has been expanding since that hot, dense, nasty mess
• 18:46
  Speaker 1: at the very beginning. Okay, And just to put them
• 18:48
  Speaker 1: into perspective, the Solar system is four point five billion
• 18:53
  Speaker 1: years old, that's right. So solar system has only been
• 18:55
  Speaker 1: around for the last third of this party. There was
• 18:58
  Speaker 1: ten billion years almost when we didn't even have our star, right, Wow,
• 19:02
  Speaker 1: So the two thirds of the universe there was nothing
• 19:05
  Speaker 1: where we are. Oh, there might have been stuff, right,
• 19:07
  Speaker 1: there might have been other stars, there might have been
• 19:09
  Speaker 1: globular clusters or gas or whatever. But our star took
• 19:12
  Speaker 1: ten billion years to even form. Wow. Okay. And by that,
• 19:17
  Speaker 1: by the same account, the Earth itself is about four
• 19:20
  Speaker 1: billion years old, that's right. Yeah, it took less than
• 19:24
  Speaker 1: a billion years for life to start on Earth. Yeah,
• 19:26
  Speaker 1: and then to put that in scale, my families university,
• 19:29
  Speaker 1: you see, Irvine is fifty years old, right, so now
• 19:33
  Speaker 1: the party has started. Well, the United States is only
• 19:37
  Speaker 1: about It always blows my mind a little bit. In
• 19:39
  Speaker 1: the United States, it's only like two d and fifty
• 19:42
  Speaker 1: years old, lessan two fifty years old. I know. My
• 19:44
  Speaker 1: brother keeps reminding me of that because his university is
• 19:47
  Speaker 1: like three times as old as our country. Right. He's
• 19:49
  Speaker 1: at Oxford, so they have traditions, they have like probably
• 19:53
  Speaker 1: have silver ware over there that's older than our country.
• 19:55
  Speaker 1: So he's he's a younger brother and he's like trying
• 19:57
  Speaker 1: to find something to get to tab over. You aren't
• 20:02
  Speaker 1: always aren't younger brothers always doing that? No, he is
• 20:04
  Speaker 1: an academic rock star at Oxford, and so he gets
• 20:07
  Speaker 1: to um, he gets to look down and the rest
• 20:09
  Speaker 1: of us at fairly new universities. Okay, so thirteen point
• 20:12
  Speaker 1: eight billion years old? That's how old the universe we
• 20:16
  Speaker 1: think it is? And how do how do we know that?
• 20:18
  Speaker 1: How do we know there is there a birth certificate?
• 20:20
  Speaker 1: Is there like DNA evidence? Well, I've been asking your mom,
• 20:24
  Speaker 1: but she claims had not been around then. So we
• 20:27
  Speaker 1: have to figure it out for ourselves. Um, there's basically
• 20:30
  Speaker 1: two ways that we we know the age of the universe,
• 20:33
  Speaker 1: And this is really classic science strategy. Is like, find
• 20:36
  Speaker 1: two completely separate, independent ways of asking the same question,
• 20:40
  Speaker 1: and then if they agree, then awesome. You think probably
• 20:44
  Speaker 1: you haven't figured out and if they don't agree, then
• 20:46
  Speaker 1: you know something's wrong. Like two independent experts, yeah, or
• 20:50
  Speaker 1: two suspects more like like if you're a detective, you're
• 20:52
  Speaker 1: trying to figure out, um, you know, who did something.
• 20:54
  Speaker 1: You find two suspects, you separate them, You ask them
• 20:56
  Speaker 1: questions separately. If they tell you all the same details,
• 21:00
  Speaker 1: they're probably telling the truth, right. If they give you
• 21:01
  Speaker 1: totally different stories, then you know they're lying. So science
• 21:04
  Speaker 1: is sort of like that. Okay, so what's the first
• 21:06
  Speaker 1: way that we know how old the universe is? The
• 21:08
  Speaker 1: first way is just looking for old stuff. Like if
• 21:12
  Speaker 1: you find something in the universe that's fifty billion years old,
• 21:15
  Speaker 1: then you know the universe is at least fifty billion
• 21:17
  Speaker 1: years old. Right, It's not very complicated. So you just
• 21:20
  Speaker 1: look around and you try to figure out how old
• 21:22
  Speaker 1: is the stuff around us, And that's it's a sort
• 21:24
  Speaker 1: of a lower limit on the age of the universe.
• 21:26
  Speaker 1: So if you find a rock that's sixty billion years old,
• 21:29
  Speaker 1: then you know the universe must be at least sixty
• 21:31
  Speaker 1: billion years old, that's right. Yeah. Or if you find
• 21:34
  Speaker 1: an unpaid bill from fourteen billion years ago, right, then
• 21:36
  Speaker 1: you know you know your universe is about to end,
• 21:43
  Speaker 1: that's right. You know exactly they're coming for you. Um, yeah,
• 21:46
  Speaker 1: and um. But that's a tricky thing to do, right,
• 21:48
  Speaker 1: how do you know the age of stuff? Right? We've
• 21:50
  Speaker 1: changed one question how do you know the age of
• 21:52
  Speaker 1: the universe into another question, which is how do you
• 21:55
  Speaker 1: know the age of stuff we see around us? Right? Yeah, Well,
• 21:58
  Speaker 1: what's the oldest stuff that we know about? Then? Yeah,
• 22:01
  Speaker 1: the oldest stuff that we know about is stars basically,
• 22:05
  Speaker 1: I mean, there's this a caveat there with the cosmic
• 22:07
  Speaker 1: microwave background, which we we know, um is a little
• 22:10
  Speaker 1: bit older, but that's more difficult to age. But direct
• 22:13
  Speaker 1: stuff that we can see that we can ask the
• 22:15
  Speaker 1: question how old is it our stars? And we look
• 22:18
  Speaker 1: around and we look for really really old stars and
• 22:22
  Speaker 1: and and this is a tricky thing to do. But
• 22:24
  Speaker 1: what you can do is you can look for blobs
• 22:26
  Speaker 1: of stars they're called globular clusters. These are collections of stars.
• 22:30
  Speaker 1: There's sort of like many galaxies. I mean, they have
• 22:32
  Speaker 1: a whole different name from them because of the sized distinction.
• 22:35
  Speaker 1: But they're called globular clusters. He didn't like mini galaxies galaxinos.
• 22:40
  Speaker 1: I thought that would have been good glaxin exactly. That
• 22:45
  Speaker 1: sounds like a nice pasta. I'll have the galaxins with anchovies, please. Um. Yes.
• 22:49
  Speaker 1: So you look at these globular clusters and you ask
• 22:52
  Speaker 1: how old are they? How old are the stars in
• 22:54
  Speaker 1: these globular clusters. And it's hard to know how old
• 22:57
  Speaker 1: an individual star is, but you can look at a
• 22:59
  Speaker 1: group of them and you can figure out how old
• 23:01
  Speaker 1: that group is, really, yeah, based on which ones are
• 23:04
  Speaker 1: still there and which ones are not there anymore. And
• 23:07
  Speaker 1: the reason is that stars have different life spans. Right,
• 23:10
  Speaker 1: So you form a bunch of stars, and um, they
• 23:13
  Speaker 1: form out of gas and dust. They coalesce with gravity,
• 23:15
  Speaker 1: and you get some really big ones and you get
• 23:17
  Speaker 1: some really little ones. Now, the big ones burn really
• 23:20
  Speaker 1: fast and they don't last very long, and the little
• 23:23
  Speaker 1: ones they burn a long time. They're like saving their fuel.
• 23:26
  Speaker 1: Remember stars burned by compressing hydrogen, right, and then they
• 23:29
  Speaker 1: glow and they burn it's its fusion and you can
• 23:32
  Speaker 1: listen to our podcast episode about that if you're curious
• 23:34
  Speaker 1: about that. Um But the big ones burn out pretty quickly.
• 23:37
  Speaker 1: So if you're looking at a population of stars really
• 23:39
  Speaker 1: really far away and you notice that they still have
• 23:42
  Speaker 1: a bunch of big ones in them, you know it's
• 23:44
  Speaker 1: pretty young because those ones would have burned out already
• 23:46
  Speaker 1: if it was old, like the cluster itself is young.
• 23:49
  Speaker 1: Like the cluster itself is young, exactly. And if you
• 23:52
  Speaker 1: find a club a group of stars the globular cluster
• 23:55
  Speaker 1: that only has little stars and it left, then you
• 23:58
  Speaker 1: know it's pretty old, and because has been time for
• 24:00
  Speaker 1: all the bigger stars to burn out. So what's the
• 24:03
  Speaker 1: oldest star that we know about? Or how old are
• 24:06
  Speaker 1: the oldest stars that we know about? Well, this is
• 24:08
  Speaker 1: really fascinating. It's been controversial because this is a hard
• 24:11
  Speaker 1: thing to do. You have to know how far these
• 24:13
  Speaker 1: things are away. You have to measure their light. There's
• 24:15
  Speaker 1: a connection between the color of the star and its size,
• 24:19
  Speaker 1: so it's a lot of intermediate steps. Right, you see
• 24:22
  Speaker 1: the color that tells you the size that you can
• 24:24
  Speaker 1: make a distribution of the sizes. There's a lot of
• 24:26
  Speaker 1: steps that go along, and there's a lot of uncertainty
• 24:28
  Speaker 1: and um. Things happen very quickly in the beginning of
• 24:32
  Speaker 1: a life cycle of a globular cluster, like the big
• 24:34
  Speaker 1: bright stars burn out fast. Near the end, things happen
• 24:37
  Speaker 1: more slowly, which means for really old stuff, the uncertainties
• 24:40
  Speaker 1: are pretty large. Like it's hard to tell the difference
• 24:43
  Speaker 1: between a ten billion year old globular cluster and an
• 24:47
  Speaker 1: eleven billion year old, but between one and two billion
• 24:50
  Speaker 1: is easier. So people have been looking at these things
• 24:53
  Speaker 1: for a while, and the oldest ones we found are
• 24:55
  Speaker 1: something like thirteen billion years old. That's a very recent estimate.
• 24:59
  Speaker 1: A till like twenty years ago, people thought they had
• 25:02
  Speaker 1: found globular clusters that were like twenty billion years old
• 25:05
  Speaker 1: or even thirty billion years old. Did you say thirty thirty? Yeah,
• 25:09
  Speaker 1: they think so, maybe the universe is thirty billion years old.
• 25:12
  Speaker 1: Well that's what they thought. For a while. They had
• 25:14
  Speaker 1: this one measurement from the stars that was saying like
• 25:16
  Speaker 1: twenty or thirty billion years old, and they thought, well,
• 25:19
  Speaker 1: let's compare that to the measure to other ways we
• 25:21
  Speaker 1: can measure the age of the universe. Now the most
• 25:24
  Speaker 1: current one that they in the end, they found some
• 25:26
  Speaker 1: some mistakes and they updated it, and they weren't like
• 25:29
  Speaker 1: you know, um, somebody goofed by adding one plus one
• 25:31
  Speaker 1: making three. You know, we just got a better understanding
• 25:34
  Speaker 1: of how stars evolved and how they burn and how
• 25:36
  Speaker 1: to do these calibrations. And now the more recent updates
• 25:38
  Speaker 1: are like thirteen billion years old. But for a while
• 25:40
  Speaker 1: it seemed like those globular clusters were suggesting the universe
• 25:45
  Speaker 1: is older than twenty billion years. So so there are
• 25:47
  Speaker 1: things out there in the universe that we're there when
• 25:50
  Speaker 1: the universe started that are still around today. Well not quite.
• 25:54
  Speaker 1: When the universe started, right, We're looking at stars, and
• 25:57
  Speaker 1: you know the universe started, there was the Big Bang.
• 25:59
  Speaker 1: There's a mess of plasma things spread out and cooled off,
• 26:02
  Speaker 1: and then stars formed from that gas and dust. Those
• 26:04
  Speaker 1: it called the first generation stars. None of those stars
• 26:07
  Speaker 1: are still around. We can't see those stars. Nobody's ever
• 26:09
  Speaker 1: seen those We're looking for them. It's people want to
• 26:11
  Speaker 1: understand it, but nobody's seen those stars. The o G
• 26:14
  Speaker 1: stars exactly back when stars were cool, man, back when
• 26:19
  Speaker 1: they were hot. Um, yeah, and then those didn't last
• 26:22
  Speaker 1: very long. And then they know they burned, they cool,
• 26:24
  Speaker 1: they exploded supernovas, and you have this, they gather their
• 26:27
  Speaker 1: back together. You have the second generation of stars. Remember
• 26:30
  Speaker 1: stars are in this cycle, right, They burn, they then
• 26:33
  Speaker 1: they explode and their fuel gets spread out into the universe.
• 26:36
  Speaker 1: Then the gathered back together and make another cycle. And
• 26:39
  Speaker 1: so the second or third generation of the sort of
• 26:41
  Speaker 1: the oldest stars that we can see so far. And
• 26:44
  Speaker 1: that's why it's a lower limit, right, we see something
• 26:46
  Speaker 1: super old. We don't know if the universe is older,
• 26:49
  Speaker 1: how much older than that the universe is. We just
• 26:51
  Speaker 1: know it's at least that old. It's like finding a
• 26:55
  Speaker 1: relic from an ancient civilization. You know that the civilization
• 26:59
  Speaker 1: is at least at all, but it could have been
• 27:00
  Speaker 1: around for much longer. Just because you haven't found something older,
• 27:03
  Speaker 1: it doesn't mean that it wasn't older. That's right, exactly.
• 27:05
  Speaker 1: It's such a lower limit. And currently that lower limit
• 27:08
  Speaker 1: is about thirteen billion years old. That's the oldest thing
• 27:10
  Speaker 1: that we found. So we're seeing things from the very
• 27:13
  Speaker 1: very early universe, not exactly from the beginning, right, but
• 27:16
  Speaker 1: from very very early on, which is pretty awesome. Right,
• 27:19
  Speaker 1: that's like the ancient history of the universe. It's I
• 27:21
  Speaker 1: think that's super cool. Yeah. Imagine like coming up to
• 27:24
  Speaker 1: these clusters and you're staring at something that's been around
• 27:28
  Speaker 1: for thirteen billion years old. Yeah, that would be pretty amazing. Yeah. Well,
• 27:31
  Speaker 1: I mean I'm already just flabbergasted looking down at the Earth. Right,
• 27:35
  Speaker 1: the Earth has been around for five billion years. It's
• 27:37
  Speaker 1: such an ancient rock. It's seen so much history. I
• 27:40
  Speaker 1: think about that when I you know, we just walk
• 27:42
  Speaker 1: across the planet, I wonder like, who else is stepped here.
• 27:45
  Speaker 1: That's one of the things that makes me love those
• 27:47
  Speaker 1: um footprints, Right, you can see like footprints of dinosaurs
• 27:50
  Speaker 1: from hundreds of millions of years ago, like they were
• 27:52
  Speaker 1: just like walking along boop um. You know, so much
• 27:55
  Speaker 1: has happened on this planet. We don't we're not even
• 27:57
  Speaker 1: aware of. There's so much history that's just been lost
• 28:00
  Speaker 1: that will never know. Okay, So that's one way we
• 28:07
  Speaker 1: know how old d universe is. What's the other way
• 28:09
  Speaker 1: we know? The other way is by looking at the
• 28:11
  Speaker 1: expansion of the universe. We know that the universe is
• 28:14
  Speaker 1: spreading out. Things are moving away from us, and they're
• 28:17
  Speaker 1: moving away from us faster and faster every year, and
• 28:20
  Speaker 1: we can measure that. We look out in the universe
• 28:23
  Speaker 1: and we see how fast things are moving away from us.
• 28:25
  Speaker 1: We can measure that by looking at how the light
• 28:27
  Speaker 1: from them is stretched. Things that are moving away from
• 28:30
  Speaker 1: you have their light waves stretched out longer, they turn
• 28:33
  Speaker 1: more red. Things that are moving towards you have their
• 28:35
  Speaker 1: light waves squeezed, they turn more blue. This is the
• 28:38
  Speaker 1: Doppler effect. It's the same effect that makes like a
• 28:40
  Speaker 1: police siren sound different as it's approaching you and leaving you. Right,
• 28:45
  Speaker 1: So we can use that to measure how fast things
• 28:47
  Speaker 1: are moving away from us. And if you remember our
• 28:49
  Speaker 1: podcast episode about dark energy and the expansion of the universe,
• 28:53
  Speaker 1: we have these really cool standard candles are called supernova
• 28:56
  Speaker 1: type one a supernova, and we we know how bright
• 29:00
  Speaker 1: they should be, and we can look at them, we
• 29:01
  Speaker 1: can measure their velocity, we know how far away they are,
• 29:04
  Speaker 1: so use that to measure how fast the universe is expanding.
• 29:07
  Speaker 1: That's important because remember we talked about the definition of
• 29:10
  Speaker 1: the start was really what we're doing when we're measuring
• 29:13
  Speaker 1: the age of the universes, we're saying how long has
• 29:15
  Speaker 1: the universe been expanding since that hot date. And if
• 29:18
  Speaker 1: you know, um, the expansion rate, then you can extrapolate backwards.
• 29:23
  Speaker 1: So we we we hit the rewind button from what
• 29:27
  Speaker 1: how fast we think the universe is expanding, and that
• 29:30
  Speaker 1: makes the university you watch it in reverse, makes the
• 29:33
  Speaker 1: universe go down, down, down, down down into a very
• 29:35
  Speaker 1: small blob. Yeah, exactly. The Ebreody starts talking finding because
• 29:39
  Speaker 1: of backwards. Yeah. And the critical thing is that you
• 29:43
  Speaker 1: have to measure the rate, right We have to know
• 29:44
  Speaker 1: the expansion rate to know how fast to rewind, and
• 29:48
  Speaker 1: we have to know the expansion right now, and the
• 29:49
  Speaker 1: expansion made a billion years ago and ten billion years ago.
• 29:52
  Speaker 1: And we can do all that because remember, the further
• 29:55
  Speaker 1: we look out into space, the further we're looking back
• 29:57
  Speaker 1: into history, and we can see the expansion and right now,
• 30:00
  Speaker 1: we can see it a while ago, we can see
• 30:02
  Speaker 1: it a long time ago. Like the history of the
• 30:04
  Speaker 1: universe is written out there in the stars, like you
• 30:07
  Speaker 1: can tell, yeah, exactly, how fascinating we're expanding throughout the
• 30:10
  Speaker 1: history of the universe. Yeah, and our history is out
• 30:13
  Speaker 1: there also. You know, light left the Earth um when
• 30:16
  Speaker 1: you were ten, and you you know, did something embarrassing
• 30:19
  Speaker 1: at your cousin's birthday party. Light from that event left
• 30:22
  Speaker 1: the earth and is still out there, and somebody could
• 30:24
  Speaker 1: capture it and see that, right, even though it happened
• 30:27
  Speaker 1: years ago, So all that information is still out there. Yeah,
• 30:30
  Speaker 1: so watch out, So watch out. Light come back and
• 30:34
  Speaker 1: and expose your ten year old antics. That's right. Well,
• 30:37
  Speaker 1: when the aliens come, they'll have seen it, right, so
• 30:39
  Speaker 1: they'll know who's been naughty and who's been nice. Santa
• 30:42
  Speaker 1: is an alien? Oh? Did I just reveal that on
• 30:46
  Speaker 1: the air. Oops? Yes, Santa is an alien. Um. I
• 30:50
  Speaker 1: mean Santa can do a whole bunch of stuff that
• 30:52
  Speaker 1: nobody else can do, right. I think having him be
• 30:53
  Speaker 1: an alien with supertech is really the only reasonable expert
• 30:56
  Speaker 1: would explain it. Santa myth boom, We just saw that
• 31:00
  Speaker 1: mystery right there. Well, this is a perfect point to
• 31:03
  Speaker 1: take a break. So if you know the expansion rate
• 31:18
  Speaker 1: the universe, you can rewind back and we actually measure
• 31:20
  Speaker 1: the expansion RDE two different ways. One is just by
• 31:23
  Speaker 1: looking at how things are moving right right these stars.
• 31:27
  Speaker 1: The other is by looking at the cosmic microwave background.
• 31:31
  Speaker 1: This is the light from the very early moments of
• 31:33
  Speaker 1: the universe. That also tells us how old the universe is. Yeah,
• 31:37
  Speaker 1: it contains an incredible amount of information about what was
• 31:40
  Speaker 1: going on in the early universe, how much dark matter
• 31:42
  Speaker 1: there was, how much normal matter there was, how dense
• 31:45
  Speaker 1: it was, all of that stuff and all that information
• 31:49
  Speaker 1: in the end can tell you about the expansion rate
• 31:51
  Speaker 1: of the universe. Um. But you can extract the expansion
• 31:54
  Speaker 1: rate directly from that. That's actually the most precise way
• 31:57
  Speaker 1: to do it UM. And then once you know the
• 31:58
  Speaker 1: expansion rate, you can rewind the universe to figure out
• 32:01
  Speaker 1: how old it is. And that's the measurement that tells
• 32:03
  Speaker 1: us it's thirteen point eight billion years, and the uncertainty
• 32:06
  Speaker 1: on that it's about twenty one million years. So it's
• 32:09
  Speaker 1: pretty accurate plus or minus twenty one million years, depends
• 32:12
  Speaker 1: on your scale. But it's kind of interesting that, you know,
• 32:15
  Speaker 1: scientists hit the rewind button, right, we look at into
• 32:17
  Speaker 1: the stars, we hit we pressed the rewind button. We
• 32:20
  Speaker 1: see it all compressed, and then we sort of stop
• 32:23
  Speaker 1: once it gets really small, right, because we a we
• 32:26
  Speaker 1: can't rewind further, but also kind of conceptually right, like
• 32:30
  Speaker 1: we we can't imagine there being anything before that or
• 32:33
  Speaker 1: we can't imagine anything surviving being that small. Yeah, and
• 32:37
  Speaker 1: we have to ask questions like what does it even mean?
• 32:39
  Speaker 1: You know, Um, space and time started at the Big Bang?
• 32:42
  Speaker 1: So can you count before the Big Bang? You get
• 32:45
  Speaker 1: into really really difficult philosophical waters. Absolutely, um. And you know,
• 32:50
  Speaker 1: it's only recently that we've known this, Like this seems
• 32:53
  Speaker 1: to like going to be an important piece of information.
• 32:54
  Speaker 1: It tells me something about who I am and how
• 32:56
  Speaker 1: to live my life and how meaningless it is. But
• 32:59
  Speaker 1: it's sort of a new piece of information. You know,
• 33:01
  Speaker 1: Like a hundred years ago, people thought the universe was
• 33:05
  Speaker 1: steady state, right, that there was just a bunch of
• 33:07
  Speaker 1: stars out there and they've basically always been there, and
• 33:10
  Speaker 1: the universe wasn't expanding or contracting. It didn't have a
• 33:13
  Speaker 1: interesting history or a moment of birth. It's just been
• 33:15
  Speaker 1: around forever. This was a hundred years ago, right, only
• 33:19
  Speaker 1: only a hundred years ago, so from most of human history.
• 33:21
  Speaker 1: First of all, for most of the ministry, we didn't
• 33:23
  Speaker 1: understand anything about anything, right, so we were basically completely
• 33:26
  Speaker 1: all ignory missus um. You just exalted most of humanity.
• 33:30
  Speaker 1: But go ahead, I mean, in the best possible. Way
• 33:35
  Speaker 1: Um but yeah, um, And only about a hundred years
• 33:39
  Speaker 1: ago do we even figure out that there might have
• 33:40
  Speaker 1: been a beginning, that there was this expansion, which suggests,
• 33:43
  Speaker 1: you know, that that that there was that if you
• 33:45
  Speaker 1: rewound it, you got back to a very early, hot,
• 33:48
  Speaker 1: nasty state. A hundred years ago, we thought the universe
• 33:51
  Speaker 1: had been around forever, right, So yeah, like forever infinity right? Yeah?
• 33:56
  Speaker 1: So what was that like to learn that the universe, uh,
• 33:58
  Speaker 1: to go from age of the uni versus infinity to
• 34:01
  Speaker 1: agees you know, in the in the billions of years.
• 34:03
  Speaker 1: And it wasn't until the fifties that we had any
• 34:05
  Speaker 1: sort of accurate estimate because these things are hard to measure.
• 34:07
  Speaker 1: It's taken decades to get the technology and the math
• 34:10
  Speaker 1: and the physics models. So it's in the fifties that
• 34:12
  Speaker 1: really had the first accurate estimate of the universe's age
• 34:16
  Speaker 1: about fourteen billion years wow. Okay, so the universe is
• 34:23
  Speaker 1: thirteen point eight billion years old plus or minus twenty
• 34:27
  Speaker 1: one million years old. And so what does that mean?
• 34:30
  Speaker 1: What does that What does that tell us about how
• 34:32
  Speaker 1: the universe came to be or where it's all going?
• 34:35
  Speaker 1: It tells us something about how far we are along.
• 34:37
  Speaker 1: You know, we know that we've we've been around for
• 34:40
  Speaker 1: long enough for galaxies to form, right, for galaxies to
• 34:43
  Speaker 1: spin for a while, for stars to form and explode
• 34:46
  Speaker 1: and coalesce again in form and explode. Right, we're not
• 34:48
  Speaker 1: in the very first few moments of the universe. But
• 34:51
  Speaker 1: we don't really know much more than that. Yeah, and
• 34:53
  Speaker 1: more important, we don't even know how old the universe
• 34:56
  Speaker 1: is going to be, right, We don't know how old
• 34:58
  Speaker 1: the universe is going to be around. So we could
• 35:01
  Speaker 1: be in a very early part of the universe, or
• 35:04
  Speaker 1: we could be in a really late part of the universe.
• 35:05
  Speaker 1: We don't really know. No, we have no idea exactly. Um,
• 35:08
  Speaker 1: it could be that in a trillion years. There are
• 35:11
  Speaker 1: life forms that are studying the age of the universe
• 35:14
  Speaker 1: and they think about this little this first little bit,
• 35:16
  Speaker 1: the first fifteen billion years as like the big bang.
• 35:19
  Speaker 1: Right to them, this could have just been like the
• 35:22
  Speaker 1: engine just getting started, you know, platform from stars and galaxies.
• 35:26
  Speaker 1: We don't know, and we don't know if this part
• 35:28
  Speaker 1: of the age of the universe is typical, right, Like,
• 35:30
  Speaker 1: it could be that things go along and everything turns
• 35:33
  Speaker 1: to black holes and they have like only black holes
• 35:35
  Speaker 1: for a trillion years. Right, Um, so we really don't know.
• 35:39
  Speaker 1: When is the puberty of the universe? Right things changing?
• 35:43
  Speaker 1: Is it already grown up? We don't know. So maybe
• 35:45
  Speaker 1: the real question we should be asking, the one that's
• 35:47
  Speaker 1: less rude, is how young the universe is? Young? Is
• 35:52
  Speaker 1: the universe exactly? Hey, universe, how do you feel? You're
• 35:55
  Speaker 1: feeling pretty good? You got some joint pain. You've been
• 35:58
  Speaker 1: planning for your retirement. Yeah, you know, like if you
• 36:01
  Speaker 1: knew you were going to live to a thousand years old,
• 36:03
  Speaker 1: you would say things like, oh, I'm only forty two
• 36:05
  Speaker 1: years young instead of forty two years old. That's right.
• 36:09
  Speaker 1: If I knew I was going to live to a thousand,
• 36:11
  Speaker 1: I would have started saving for retirement a lot, a
• 36:13
  Speaker 1: lot earlier. You want to be retired for nine thousand,
• 36:17
  Speaker 1: nine hundred and sixty years. No, honestly, I'm never going
• 36:21
  Speaker 1: to retire. I mean, I have tenure. Why should ever
• 36:22
  Speaker 1: retirement to sit in my office for the next year
• 36:24
  Speaker 1: and you're already retired mentally mentally retired? You know you
• 36:32
  Speaker 1: do your best work and you have tenure. That's exactly
• 36:34
  Speaker 1: the point. You're free to think and expand and go
• 36:37
  Speaker 1: to crazy places in your career, like recording a podcast
• 36:40
  Speaker 1: with a cartoonist, right, yeah, sure, yeah, And the universe
• 36:43
  Speaker 1: is fifty years old. Universe's fifty years young, alright, everyone.
• 36:48
  Speaker 1: So that's the answer to the question how old is
• 36:51
  Speaker 1: the universe? And how do we know? Or how young
• 36:53
  Speaker 1: is the universe? How young isn't the universe? Oh my god, Universe,
• 36:57
  Speaker 1: you look good. You're looking sparkly. That's right, keep burning bright, Universe.
• 37:04
  Speaker 1: You're happy to be around. See you next time. Thanks
• 37:07
  Speaker 1: for tuning in. If you still have a question after
• 37:17
  Speaker 1: listening to all these explanations, please drop us a line.
• 37:20
  Speaker 1: We'd love to hear from you. You can find us
• 37:22
  Speaker 1: at Facebook, Twitter, and Instagram at Daniel and Jorge that's
• 37:26
  Speaker 1: one word, or email us at Feedback at Daniel and
• 37:30
  Speaker 1: Jorge dot com.