Latest / Daniel and Kelly’s Extraordinary Universe / What is making the Universe explode?

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What is making the Universe explode? · Daniel and Kelly’s Extraordinary Universe

0:05
Speaker 1: Some of the most amazing moments in science were totally unexpected.
0:09
Speaker 1: You mean, like the discovery of microwave ovens or slinky
0:13
Speaker 1: So I heard it was also discovered by accident. Yeah,
0:16
Speaker 1: but I'm thinking about the times when you go out
0:17
Speaker 1: there just to double check something, something you thought you
0:20
Speaker 1: already understood, but you find an answer which makes no
0:22
Speaker 1: sense and forced you to change how you'd see things. Yeah.
0:25
Speaker 1: Like I heard one of the most fundamental things in
0:27
Speaker 1: the universe was actually discovered this way by accident, and
0:31
Speaker 1: it's totally amazing. It makes me wish that I had
0:33
Speaker 1: been involved, and it makes us see the universe differently,
0:36
Speaker 1: makes us see everything differently. Is it more impressive than
0:39
Speaker 1: as slinky in a microwave? That's pretty hard to top,
0:43
Speaker 1: but I think this one does. Hi, I'm RhE make cartoonists,
0:58
Speaker 1: and I'm Daniel. I'm a article physicists, and this is
1:01
Speaker 1: our podcast. Daniel and Jorgey explain the universe today on
1:06
Speaker 1: the program. What is dark energy and why is it
1:13
Speaker 1: everywhere in filling the universe? Is it powerful? Is it dangerous?
1:18
Speaker 1: Is it dark after all? Will it stain your clothes?
1:21
Speaker 1: And most important, why is it causing the universe to explode.
1:26
Speaker 1: The universe is exploding, people, but don't get out of
1:28
Speaker 1: your cars. It's going to take a while. Dark energy
1:31
Speaker 1: is a mysterious topic. We went around and we asked people,
1:34
Speaker 1: what do you know about dark energy? Um, is it
1:37
Speaker 1: like empty space? I'm not sure. No, I have no
1:39
Speaker 1: idea about it. It's like empty energy. Is dark energy
1:44
Speaker 1: something with black holes? I don't know, but that's my speculation.
1:48
Speaker 1: So most people really seem to have almost no idea
1:51
Speaker 1: what dark energy is, which as a physicist, really surprised
1:54
Speaker 1: me because it's one of the most dramatic and amazing
1:56
Speaker 1: discoveries of the last thirty years. Yeah, it's but people
2:00
Speaker 1: what it has seemed to have heard about it, right,
2:01
Speaker 1: It sounded really familiar, but they didn't know what it was. Yeah,
2:04
Speaker 1: some people thought it was dark matter. Some people maybe
2:06
Speaker 1: thought it was something in black panther like. People really
2:09
Speaker 1: didn't seem to have a good grip on what dark
2:12
Speaker 1: energy is, which is amazing, not just because it was
2:14
Speaker 1: a big discovery, but because it has huge consequences for
2:18
Speaker 1: our lives. Yeah, it's a great name. I mean, I
2:21
Speaker 1: think it's easy to see why people would confuse it
2:23
Speaker 1: with dark matter, they're both dark and that's right. It
2:26
Speaker 1: is a cool name, dark energy. It sounds so mysterious, though,
2:29
Speaker 1: you're right. In the in like the HR meeting where
2:31
Speaker 1: they decided what to call this weird physics thing, it
2:34
Speaker 1: should have considered the fact that dark matter and dark
2:36
Speaker 1: energy sounded like. I wonder if they do focus groups
2:38
Speaker 1: when they do that kind of thing. Do you think
2:39
Speaker 1: they thought, Hey, all those dark matter people get a
2:41
Speaker 1: ton of grant money. If we call our stark energy,
2:45
Speaker 1: we could also get some of that money. I'm sure.
2:47
Speaker 1: I'm sure that was the number one concern in their minds. Yeah,
2:50
Speaker 1: how will this play in my next grand proposal? Anyway?
2:55
Speaker 1: Let's tell people what dark energy is and why it's
2:57
Speaker 1: so important. Yeah, well, first of all, it's a huge,
3:00
Speaker 1: huge deal, right, Like, it's not like an obscure thing
3:03
Speaker 1: in physics. It's like a huge part of the universe.
3:06
Speaker 1: That's right. Most of the energy and the universe is
3:08
Speaker 1: actually taken up with dark energy, like sixties, right, that's right. Fully,
3:13
Speaker 1: two thirds of all the energy in the universe is
3:16
Speaker 1: devoted to this weird, mysterious force called dark energy, and
3:20
Speaker 1: that's about all we know about it. Like when you
3:22
Speaker 1: think of the universe and like atoms and protons and
3:25
Speaker 1: electrons and rocks, asteroids, planets, all those suns, hamsters and
3:31
Speaker 1: then the hamsters, yeah, hamsters, all that stuff out there
3:36
Speaker 1: in the universe. Stars. That's not all there is to
3:39
Speaker 1: it to the universe, right, A whole bunch of it
3:42
Speaker 1: is dark energy, that's right. Yeah, most of the stuff
3:45
Speaker 1: in the universe is not the kind of stuff that
3:47
Speaker 1: we see around us, as you were saying, even stars
3:50
Speaker 1: and planets and gas and dust, that all adds up
3:51
Speaker 1: to a tiny little slipper like five turns out. And
3:55
Speaker 1: this is the kind of stuff we've only learned recently.
3:57
Speaker 1: Most of the universe is weird. Stuff we never even
4:00
Speaker 1: thought about, we never even would have included in a
4:02
Speaker 1: pie chart of the universe thirty years ago. Is the
4:05
Speaker 1: biggest piece of the pie. It's this big kind of
4:08
Speaker 1: mysterious energy that's out there, that's right. So imagine, for example,
4:13
Speaker 1: you take like a cubic meter of space and you
4:16
Speaker 1: ask what's in it. Well, on average, you average over
4:19
Speaker 1: the whole universe that we can see, it has about
4:21
Speaker 1: five or six hydrogen atoms worth of energy. And most
4:26
Speaker 1: of that is not matter or or stuff that you're
4:29
Speaker 1: familiar with. Most of it is dark energy, and another
4:32
Speaker 1: big chunk of it is something called dark matter, which
4:34
Speaker 1: we can talk about it in another episode. Yeah, and
4:37
Speaker 1: and like dark energy is all around us, right, like
4:39
Speaker 1: right now, two thirds of the room right now that
4:42
Speaker 1: I'm in is filled with dark energy. That's right, most
4:45
Speaker 1: of the energy in the universe and most of the
4:47
Speaker 1: energy everywhere. And dark energy is not something that's out
4:50
Speaker 1: there in space. You're exactly right. It's here, it's with you.
4:52
Speaker 1: It's between your toes. It's getting refrigerator just other dark
4:56
Speaker 1: matter between my toes. Let's be honest. I don't think
5:00
Speaker 1: I want to know what he does, whether it's a
5:03
Speaker 1: cosmic mystery physics or not. Yeah, let's not let's not
5:06
Speaker 1: get into my toes on this. On this podcast, Daniel
5:11
Speaker 1: Jorge explained the universe and Jorge's toes. That's right, that's
5:14
Speaker 1: a winner right there. Um. But yeah, so it's a
5:17
Speaker 1: huge deal. It's all around this and it's causing the
5:19
Speaker 1: universe to explode. So that's that's kind of distressing. Yeah.
5:23
Speaker 1: Not only is it turned out to be most of
5:25
Speaker 1: the universe, it has huge consequences. Right. The universe is
5:28
Speaker 1: exploding in every direction, and in some ways dark energy
5:32
Speaker 1: is causing the universe to explode. Another way to think
5:35
Speaker 1: about it is that dark energy is our description of
5:38
Speaker 1: the fact that it is exploding. Like we saw the
5:41
Speaker 1: universe is exploding. We named that dark energy. It's not
5:45
Speaker 1: like there's two separate things where oh, here's dark energy,
5:48
Speaker 1: we know that's the thing. Here's it's cause it's more
5:50
Speaker 1: like dark energy is the description of the fact that
5:52
Speaker 1: the universe is exploding and we don't really know why.
5:55
Speaker 1: It's another name for the explosion of the universe. It's
5:58
Speaker 1: a fancy tide or our lack of understanding the explosion
6:02
Speaker 1: in the universe. It's like you don't understand something. You
6:04
Speaker 1: have the pr version. We could have called it what
6:07
Speaker 1: is going on with the universe? But dark energy sounds
6:10
Speaker 1: better w two F energy your t F universe man, Yeah, exactly.
6:19
Speaker 1: Well let's get into that. So how did how do
6:22
Speaker 1: we find out about this dark energy that's all around
6:24
Speaker 1: us and it's causing the universe to explode. Well, it's
6:27
Speaker 1: one of my favorite stories in science because it's a
6:29
Speaker 1: story where the answer was a surprise. You know, scientists
6:32
Speaker 1: went into it asking one question and learning something totally
6:35
Speaker 1: different about the universe. The question they started with was
6:38
Speaker 1: what is the history of the universe and what is
6:41
Speaker 1: the future of the universe? Like what's going to happen eventually? Yeah, exactly,
6:45
Speaker 1: Like is this whole universe gonna keep going forever? Is
6:48
Speaker 1: it going to compress into little dot? Do I have
6:51
Speaker 1: time to like write that novel I've always been wanting
6:54
Speaker 1: to write. You definitely have time to write that novel.
6:57
Speaker 1: I have no excuse. Is it another young adult novel?
6:59
Speaker 1: Because I have enough of those already. It's called dark
7:02
Speaker 1: youth dark, um dark. So you've got vampires, you've got
7:07
Speaker 1: where wolves have dark energy beings. Yeah. And so when physicists,
7:14
Speaker 1: when physicists want to predict the future, where they typically
7:16
Speaker 1: do is look into the past, try to understand what's
7:18
Speaker 1: happened so far, and then extrapolate so to figure out
7:22
Speaker 1: what the future of the universe was. They first looked
7:24
Speaker 1: into the past and said, what's been going on so far,
7:26
Speaker 1: and let's see what direction things are going in? Right, Like, um, uh, Like,
7:34
Speaker 1: how am I doing financially? Do I have more money
7:36
Speaker 1: now than I used to have money before? And that's
7:39
Speaker 1: a that will sort of tell me, what might I
7:41
Speaker 1: might expect in the future if I don't make ill
7:42
Speaker 1: advised decisions. That's right. Yeah, if your net worth has
7:45
Speaker 1: been rising, then you expected to keep going. What if
7:48
Speaker 1: your bank account is dropping every single month, then you
7:50
Speaker 1: can expect some sort of cataclysmic event in your near future.
7:53
Speaker 1: And I need to record more podcasts to make more money.
7:56
Speaker 1: That's right, that's right. And so in the physics world,
8:00
Speaker 1: we went back to the very beginning of the universe
8:02
Speaker 1: and said, okay, the universe started with a big bang, right,
8:04
Speaker 1: and things blew up from there. And the question people
8:08
Speaker 1: had in their minds was, you know, after the Big Bang,
8:11
Speaker 1: things flying out from that huge explosion. The question was,
8:14
Speaker 1: is there enough stuff in the universe for things to
8:18
Speaker 1: slow down, for the gravity from that stuff to slow
8:21
Speaker 1: things down, stop them, and then make them fall back in.
8:25
Speaker 1: So that was one possibility people were considering that the
8:28
Speaker 1: universe would stop, the expansion, would stop um and then
8:31
Speaker 1: come back into a big crunch. So like the stuff
8:34
Speaker 1: that flew out from the Big Bang, and now the
8:36
Speaker 1: question is like, are they going to keep flying off
8:39
Speaker 1: or maybe is there enough gravity pulling it all the
8:42
Speaker 1: stuff together that it's gonna like slow down and then
8:47
Speaker 1: pull back in, just kind of like how our solar
8:51
Speaker 1: system forms. Yeah, exactly. Most of the stuff that we
8:53
Speaker 1: know around us in the in the universe was formed
8:56
Speaker 1: by gravity. Right, Gravity gathered together rocks and dust and
8:59
Speaker 1: rubb and hamsters or whatever and coalesce it together. Right.
9:03
Speaker 1: That's why the Earth is round because that's gravity's work,
9:06
Speaker 1: tumbling everything towards a smooth surface. And that's how the
9:09
Speaker 1: Sun is formed, its gravity compressing dust and gas until
9:12
Speaker 1: it gets hot enough to burn. So gravity is is
9:14
Speaker 1: very powerful force and and has a lot of time.
9:17
Speaker 1: Um it's actually one of the weakest forces, but over
9:20
Speaker 1: cosmic scales and all this time, it has enough power
9:23
Speaker 1: to pull all this stuff together and compress it into objects.
9:26
Speaker 1: So people thought, maybe that's going to happen with the
9:28
Speaker 1: whole universe. Man, Like, maybe the whole universe is gonna
9:32
Speaker 1: come back together and compress back into a tiny dot.
9:35
Speaker 1: That would be pretty amazing, like a giant cloud. Does
9:38
Speaker 1: we all just kind of come get pulled together and
9:42
Speaker 1: we maybe come back down. That's one possible way that
9:45
Speaker 1: the future the universe could end up. That's right. Yeah,
9:48
Speaker 1: So option A was the big crunch. But people didn't know,
9:52
Speaker 1: like is there enough stuff in the universe? Is there
9:54
Speaker 1: enough gravity from that stuff to pull everything back together?
9:57
Speaker 1: Because it could totally have been that the explore ocean
10:00
Speaker 1: was more powerful essentially than the gravity, and the things
10:03
Speaker 1: spread out forever. Oh, that could happen, like things that
10:06
Speaker 1: are like a grenade out in space. It just blows
10:09
Speaker 1: up so violently that gravity is too weak to pull
10:14
Speaker 1: everything back together again. That's right, yeah, And that could
10:18
Speaker 1: that could have been the fate of the universe. It
10:19
Speaker 1: could be that the universe just keeps expanding, things spread
10:22
Speaker 1: out and slow down like gravity. Gravity is still slowing
10:25
Speaker 1: things down, but it doesn't have enough power to stop
10:28
Speaker 1: it and have it fall back in. And so it
10:30
Speaker 1: could be that just spreads out forever, getting cooler and
10:34
Speaker 1: cooler and more distant until something we call the heat
10:37
Speaker 1: death of the universe. That's when everything is the same temperature. Right,
10:40
Speaker 1: So physicists were like, are we ever going to be cool?
10:44
Speaker 1: That was a front question. We'll know in about to
10:49
Speaker 1: find out if physicists are ever cool. So that's I mean,
10:52
Speaker 1: that is a very significant question, right, Like we're we
10:55
Speaker 1: live in this universe. We kind of want to know,
10:57
Speaker 1: like where is this whole thing headed? Yeah, I wonder
11:00
Speaker 1: if it's interesting to most people. To me, as a physicist,
11:03
Speaker 1: I think it's one of the most interesting questions, Like
11:06
Speaker 1: what is the future of this whole amazing, beautiful experiment
11:09
Speaker 1: we're living in, you know, is it going to go
11:11
Speaker 1: on forever? Is it going to tear uself apart? Is
11:13
Speaker 1: it going to crunch together? Like? To me, that's a
11:16
Speaker 1: really interesting question, Like do we live at the peak
11:19
Speaker 1: of it? Or are we like in the after party,
11:21
Speaker 1: you know what I mean? Like, or are we or
11:23
Speaker 1: are our great grandchildren going to be like at the
11:25
Speaker 1: peak of the universe? Yeah? I think I think that's
11:28
Speaker 1: exactly right. And I think there's an issue of context there, right,
11:30
Speaker 1: Like as humans, we are always striving to understand the
11:33
Speaker 1: context of our existence. Why is this important? What's going on?
11:37
Speaker 1: And one of those questions is like is Earth at
11:40
Speaker 1: the center of the cosmos? Is Earth even important? And
11:43
Speaker 1: another question is like that but in time? Right, like
11:45
Speaker 1: are we living at an important time? What is the
11:49
Speaker 1: future going to be? Like where do we fit in? Yeah?
11:52
Speaker 1: Are people in a billion years going to look back
11:54
Speaker 1: and say, man, I wish I'd lived when Daniel L. Jorge,
11:56
Speaker 1: we're doing. They're awesome podcasts because those were the days,
11:59
Speaker 1: many the good old days of the universe. Yeah, this
12:01
Speaker 1: podcast is peak civilization, right, podcast is peak civilization. So
12:07
Speaker 1: state tuned state that one. Let's take a quick break. Yeah.
12:21
Speaker 1: So people were thinking about those two options, right, big
12:24
Speaker 1: crunch or heat death of the universe. So option A
12:28
Speaker 1: everything comes crashing back down. Option B things just gonna
12:32
Speaker 1: float away, yeah, exactly. And so what they wanted to
12:35
Speaker 1: do was look back in time because you can't actually
12:38
Speaker 1: see the future, but it's not that hard in physics
12:40
Speaker 1: to see the past, especially in astronomy. To see the past,
12:43
Speaker 1: all you have to do is look out into space,
12:46
Speaker 1: and everything you see in space happened in the past,
12:49
Speaker 1: just because it takes light time to get here from there.
12:52
Speaker 1: It's like back in the day when there was no
12:54
Speaker 1: email or internet, you would get your news from mail letters, right,
12:59
Speaker 1: And so the further away what did actually happened? At
13:04
Speaker 1: some point the internet did not exist, Daniel, what what what?
13:08
Speaker 1: It was all dark dark mail? Ye, dark mail. So yeah,
13:14
Speaker 1: so like the further away you get a letter the
13:16
Speaker 1: older that news was, yes, exactly. And some people think, oh,
13:20
Speaker 1: that's a bummer. I think it's actually pretty cool because
13:22
Speaker 1: it lets us look into the past, and so the
13:24
Speaker 1: further out you look, the further in the back in
13:26
Speaker 1: the past you can see. And the goal is to see,
13:28
Speaker 1: like how fast is stuff moving away from us, you know,
13:31
Speaker 1: the expansion of the universe. How fast is stuff moving
13:34
Speaker 1: away from us now? And how fast was it moving
13:36
Speaker 1: away from us earlier? So we could understand like, how
13:39
Speaker 1: is this changing, what is the faith going to be?
13:41
Speaker 1: Is its slowing down? How fast is it slowing down? Yeah, So,
13:45
Speaker 1: because like if the fate of the universe was for
13:47
Speaker 1: it to crunch down, then you would see things kind
13:50
Speaker 1: of expanding slower now than before. Like before you think
13:54
Speaker 1: this would be flying out, and now they would be
13:56
Speaker 1: kind of slowing down, And so we could expect things
13:58
Speaker 1: to crunch or if we measure things to be moving
14:03
Speaker 1: at about the same now as as they were before,
14:05
Speaker 1: then maybe the fate of the universe is just to
14:07
Speaker 1: kind of keep floating off and getting cooler exactly. And
14:11
Speaker 1: so that was the question. They were like, let's look
14:13
Speaker 1: and see how things are changing. How much is it
14:15
Speaker 1: slowing down? Is slowing down a lot, which means maybe
14:18
Speaker 1: big crunch are slowing down just a little, which means
14:20
Speaker 1: maybe heat death. That was the question they asked. But
14:23
Speaker 1: it's actually fascinating how they did it because it's tricky, right.
14:26
Speaker 1: In order to know how far back in the past
14:29
Speaker 1: you're looking, you have to know how far away a
14:31
Speaker 1: star is. And that's not easy to figure out, right,
14:34
Speaker 1: because like, if you look at a star, it's um,
14:38
Speaker 1: if it's dim, you don't know if it's just like
14:39
Speaker 1: a weak star or a really far away star. It's
14:42
Speaker 1: just a little point, right, it's hard to tell. You can't, like, um,
14:45
Speaker 1: tell how far away it is just from how bright
14:47
Speaker 1: that point is. That's right. You can't tell the difference
14:49
Speaker 1: between a star that's very bright and far away and
14:52
Speaker 1: very weak and close up. Um. We have some tricks,
14:56
Speaker 1: but none of them are really good. Um. The early days,
14:59
Speaker 1: UM people used to figure out how far away stars
15:01
Speaker 1: were by seeing how they shifted as their Earth went
15:04
Speaker 1: around the sun. Because if something was really close, then
15:07
Speaker 1: you could see it sliding back and forth as the
15:09
Speaker 1: Earth went around the Sun. That's called the parallax system.
15:12
Speaker 1: It's like how you triangulate with your eyes, right, like
15:14
Speaker 1: if yes, if something looks really different when you wink
15:17
Speaker 1: one eye and you wink the other one, then it
15:19
Speaker 1: must be pretty close. But if it doesn't change a
15:22
Speaker 1: lot when you wink between eyes, then uh, it's far away. Yeah,
15:26
Speaker 1: And so that's the original way people can figure out
15:28
Speaker 1: how far stuff away is. And then it was like
15:30
Speaker 1: in the nineteen twenties when Hubble figured out a new
15:33
Speaker 1: way to look at stuff in the sky and he
15:35
Speaker 1: found a particular kind of star called a seafid that
15:39
Speaker 1: rotated and its brightness was connected to how fast it
15:42
Speaker 1: was rotating, so you could figure out by measuring its
15:45
Speaker 1: rotation how bright it is, which told you how far
15:47
Speaker 1: away it was. So he was the first one to
15:49
Speaker 1: be able to see things that were further away. And
15:51
Speaker 1: he's actually the one who figured out not just that
15:54
Speaker 1: the universe is expanding. Before that, people thought, oh, the
15:57
Speaker 1: universe is just a bunch of stars hanging in space
16:00
Speaker 1: ace And he figured out two amazing things. One is
16:03
Speaker 1: the universe is expanding, and the other is that the
16:06
Speaker 1: universe is more than just our galaxy. And what do
16:09
Speaker 1: you mean more? He figured out that there were other galaxies.
16:12
Speaker 1: That's right, before Hubble, we thought there is just our galaxy, Like,
16:16
Speaker 1: imagine just a single galaxy floating in space. That's what
16:20
Speaker 1: people thought the universe was. He saw these little smudges
16:24
Speaker 1: up in the sky that people thought, oh, these should
16:26
Speaker 1: just dust or clouds or something turns, and that he
16:29
Speaker 1: proved by measuring the distance to them, that they were
16:32
Speaker 1: way too far away to be part of our galaxy.
16:34
Speaker 1: He proved that they were actually other galaxies, and that
16:37
Speaker 1: those galaxies who were running away from us. It must
16:40
Speaker 1: have been so mind blowing to be Hubble, you know,
16:42
Speaker 1: to have this moment of realization, Uh, to understand this
16:46
Speaker 1: huge context of our of our existence. Yeah, it must
16:49
Speaker 1: be very humble to be Hubble. You know, I don't
16:54
Speaker 1: know anything about Hubble, but a lot of these famous
16:57
Speaker 1: physicists were not the nicest guys. So is that you
17:01
Speaker 1: are their stories about Hubble. I don't know any of them,
17:04
Speaker 1: but if I had to guess any random famous physicist
17:07
Speaker 1: from history, they probably got there by not being the
17:10
Speaker 1: nicest of a person. Yeah, humble. Anyway, Hubble was able
17:13
Speaker 1: to see past our galaxy, but cosmically speaking, that's not
17:17
Speaker 1: far enough to be able to tell because that's just
17:18
Speaker 1: like the last you know, a little bit of the history.
17:21
Speaker 1: Then it was in the nineties nineties, people developed a
17:24
Speaker 1: powerful new technique that let them see much further, so
17:27
Speaker 1: we could tell how far away things were that were
17:29
Speaker 1: much much, much further, and that gave us a much
17:31
Speaker 1: deeper view, further than like the nearest galaxy, yeah, really
17:36
Speaker 1: far away galaxies. And that's a new kind of star
17:39
Speaker 1: that we started to understand, called a type one, a supernova. Right,
17:43
Speaker 1: they call him like the standard candles, right, exactly the
17:46
Speaker 1: standard candles because they act the same way everywhere in
17:49
Speaker 1: the universe. And so we can tell we know how
17:51
Speaker 1: bright they are, so based on how dim they are
17:54
Speaker 1: or how bright, we can tell how far away they are.
17:57
Speaker 1: So it was in the nineties people figured this thing out, like, look,
18:00
Speaker 1: we have a new standard candle that let's look much
18:02
Speaker 1: deeper into the history of the universe and how we
18:05
Speaker 1: can answer this question. We can figure out what is
18:07
Speaker 1: the future of the universe, What is it going to be?
18:09
Speaker 1: So most stars are you can't really tell, right, some
18:12
Speaker 1: of them are dim, some of them are far away.
18:14
Speaker 1: But there are this special type of star. It always
18:17
Speaker 1: explodes the same way, so that if you see it
18:21
Speaker 1: m really bright and must be closed, or if you
18:23
Speaker 1: see it really dim, it must be far away, right,
18:26
Speaker 1: that's right. And these are not just stars, as you said,
18:27
Speaker 1: these are supernova, right, they're the end of stars. Right.
18:30
Speaker 1: That's when stars collapse and implode, followed by huge, enormous
18:35
Speaker 1: cosmic explosion. And that explosion is super bright, like a
18:38
Speaker 1: single supernova can outshine the entire galaxy it's in, but
18:43
Speaker 1: just for a few days. It's like crazily burning up
18:45
Speaker 1: all of its fuel. It's like a flare. If you
18:47
Speaker 1: set your house on fire, it's brighter than the whole neighborhood, right,
18:50
Speaker 1: but not very long. So there were you know, people
18:53
Speaker 1: figure this out, and then people um sort of split
18:56
Speaker 1: into two teams. It was a team at Berkeley and
18:58
Speaker 1: there was a team in Australia, and and they were
19:00
Speaker 1: racing to discover to get as much data as possible
19:03
Speaker 1: because supernova are not regular. It's not like you know
19:06
Speaker 1: when it's going to happen. You have to just scan
19:08
Speaker 1: the sky and hope to see one. Then it developed
19:10
Speaker 1: special technology to look through all this telescope data and
19:13
Speaker 1: try to find new stars that were appearing in the sky,
19:16
Speaker 1: because that's what a supernova looks like, looks like a
19:18
Speaker 1: bright new star that appears and then it fades over
19:20
Speaker 1: a matter of days, and if you capture enough data
19:22
Speaker 1: about it, then you can learn about its brightness and
19:25
Speaker 1: figure out how far away it was. And so finally
19:27
Speaker 1: one of them discovered, like, hey, we have a measurement
19:31
Speaker 1: for how the universe is expanding, whether it's expanding faster
19:35
Speaker 1: or slower than before. Yeah, it took a took a
19:38
Speaker 1: couple of years for them to have enough data, and
19:40
Speaker 1: it was a scramble and think, I think those people
19:42
Speaker 1: must have been working twenty hour days in the seven
19:44
Speaker 1: days a week. Yeah, everyone wanted to be the first
19:47
Speaker 1: to say like, hey, here's that measurement exactly. Finally they
19:50
Speaker 1: had this plot of how fast the universe is expanding
19:53
Speaker 1: as a function of time. And what they discovered is
19:57
Speaker 1: that the universe is not slowing down a lot or
20:00
Speaker 1: slowing down a little. So it's not option A nor
20:02
Speaker 1: option B. That's right. The universe went for secret options.
20:06
Speaker 1: See secret Ope, you didn't even know it was on
20:09
Speaker 1: the menu. And that's what we got for dinner, right.
20:12
Speaker 1: And I love when the universe does that because it's like, oh,
20:14
Speaker 1: you silly little humans, you have no idea what even
20:17
Speaker 1: question you're asking? Right? You hadn't even thought about this answer.
20:20
Speaker 1: That's right, and so secret options see is that the universe,
20:22
Speaker 1: the expansion of the universe is not slowing down at all.
20:25
Speaker 1: It's increasing. It's getting faster and faster, it's accelerating. So
20:29
Speaker 1: the fate of the universe is not that it's going
20:31
Speaker 1: to crunch down or just float away. Things are like
20:35
Speaker 1: phraising away from each other, that's right, Faster and faster
20:38
Speaker 1: every year. Something out there, we don't know what it is.
20:41
Speaker 1: We can't explain it, we don't understand it at all.
20:43
Speaker 1: Something out there is pushing all of these other galaxies
20:46
Speaker 1: away from us, and it's doing it faster and faster
20:48
Speaker 1: every year. Like if you you only need to know
20:50
Speaker 1: a little bit of physics to know that accelerating an
20:53
Speaker 1: entire galaxy hundreds of billions of stars, takes a huge
20:57
Speaker 1: amount of energy. That's why we were talking earlier about
20:59
Speaker 1: how two thirds of the energy in the universe, because
21:02
Speaker 1: it's not a small feat to expand the whole universe
21:05
Speaker 1: faster every year. Yeah, it's like these galaxies want to
21:08
Speaker 1: get together because of gravity, either pulling on each other
21:11
Speaker 1: to get closer, but something is actually pushing them apart.
21:14
Speaker 1: That's right, and that's the thing we call dark energy.
21:17
Speaker 1: So they discover this thing, total mind blow, like what
21:21
Speaker 1: the universe is totally different from what we thought it was.
21:23
Speaker 1: The fad of the universe is different from what we
21:25
Speaker 1: possibly imagined. Then there's this second big question, which is
21:28
Speaker 1: what is it? Right, we found it. We we know
21:32
Speaker 1: that it's there, we see that it's happening, but we
21:34
Speaker 1: don't understand it at all. We just observe it. Okay,
21:36
Speaker 1: but before we get into that, let's take a quick break.
21:50
Speaker 1: That's what dark energy is. It's like that thing that
21:53
Speaker 1: is pushing all the galaxies apart. That's right, the totally unexplained,
21:57
Speaker 1: ununderstood phenomena which is shredding the universe and causing it
22:01
Speaker 1: to explode and changing its future. That's what dark energy is.
22:04
Speaker 1: And most people walking in the street have no idea.
22:07
Speaker 1: It's like the phenomenon of the universe expanding faster and faster.
22:11
Speaker 1: That's dark energy. That's exactly right, like some kind of
22:14
Speaker 1: like actual like energy like a photon or some kind
22:17
Speaker 1: of like thing like we really don't know what it is.
22:20
Speaker 1: All we know is that it's energy. That's all we know.
22:24
Speaker 1: Um And we know that it's accelerating the universe. And
22:26
Speaker 1: it fascinating thing is that it's not just pushing stuff
22:30
Speaker 1: through space. Right. One way to imagine a galaxy moving
22:33
Speaker 1: away from you is that it's moving through space away
22:36
Speaker 1: from you, right, And that's what you imagine probably when
22:38
Speaker 1: you think of the Big Bang. Everything comes out of
22:40
Speaker 1: this tiny little ball and expands through space. But dark
22:43
Speaker 1: energy is doing something else. It's also creating new space
22:48
Speaker 1: between us and the other galaxies. It's not just pushing
22:50
Speaker 1: things through space. It's making new empty space. It's not
22:54
Speaker 1: pushing you and meet apart from each other. It's like
22:57
Speaker 1: it's creating more uh room, more more land in between
23:02
Speaker 1: in between us. That's right. It's making the four or
23:04
Speaker 1: five even longer. Well you know what I mean, like
23:08
Speaker 1: a like a tectonic plading now, like it comes up
23:11
Speaker 1: and it creates land and it pushes things apart. That's
23:14
Speaker 1: kind of what dark energy is doing out in space, Yes,
23:17
Speaker 1: exactly right, creating new real estate in between you and me.
23:21
Speaker 1: That's pushing me apart, further apart from you, that's right.
23:24
Speaker 1: And it's hard to think about what it means new space.
23:26
Speaker 1: What is that unless you think about space in a
23:28
Speaker 1: different way spaces and just emptiness or nothingness. As we've
23:31
Speaker 1: said on this podcast a few times, it's this dynamic
23:34
Speaker 1: physical thing. And this is one reason we think it's
23:36
Speaker 1: more than just emptiness, is that it can do this
23:38
Speaker 1: thing that emptiness can't, which is create more of itself.
23:42
Speaker 1: It's not nothing. It's like real estate, and there's more
23:45
Speaker 1: of it being created. That's right. Location, location, location, you know,
23:48
Speaker 1: it's the most important thing. Right And new space is
23:51
Speaker 1: being created all the time, and that's what dark energy
23:54
Speaker 1: is doing, is creating this new space. And we don't
23:56
Speaker 1: have any explanation for it. You know, people think about
23:58
Speaker 1: theories of what is dark energy? You could it be this?
24:00
Speaker 1: Could it be that. One idea that physicists like is
24:03
Speaker 1: to think about the energy of this empty space, like
24:06
Speaker 1: maybe space itself has energy. Maybe space can never really
24:10
Speaker 1: be empty. You know, it's full of the Higgs field,
24:12
Speaker 1: and it's full of virtual particles, and it's full of
24:14
Speaker 1: all this little quantum frothing bubblinus. Right Like by its
24:17
Speaker 1: very nature is just like this has a bubbly personality.
24:21
Speaker 1: That's right. Space is friendly. It wants to have more
24:26
Speaker 1: of itself. It's social and so one idea is maybe
24:28
Speaker 1: dark energy is this energy of empty space. Problem is,
24:32
Speaker 1: if you sit down to do the calculations, you say,
24:34
Speaker 1: all right, well, let's calculate how much energy there is
24:36
Speaker 1: an empty space, and compared to what we see, you
24:38
Speaker 1: come up with a number that's way off, like not
24:40
Speaker 1: a little bit off off by ten to the sixty
24:43
Speaker 1: and let's ten with sixty zeros beyond its error. It's
24:47
Speaker 1: a pretty big mistake. So the other fascinating thing is
24:51
Speaker 1: that it hasn't been doing it forever. It turned on
24:53
Speaker 1: about five billion years ago and started this acceleration. And
24:57
Speaker 1: again we don't know why. We don't know what turns
25:00
Speaker 1: it on. We know what we turn it off. You
25:02
Speaker 1: know what is dark energy? Like you know long walks
25:05
Speaker 1: on the beach. I don't know. We don't know very
25:07
Speaker 1: much about it. It wasn't always there from the beginning
25:09
Speaker 1: of the Big Bang. It's just some somehow five billion
25:12
Speaker 1: years ago it started pushing things more actively. Yeah, these days,
25:16
Speaker 1: the most modern picture of cosmology, I think, considers the
25:19
Speaker 1: Big Bang and dark energy to be sort of connected. Like,
25:22
Speaker 1: imagine a huge expansion of the universe in the very
25:25
Speaker 1: first few moments that we called the Big Bang or
25:27
Speaker 1: these days we call that inflation. And then that stopped
25:29
Speaker 1: and things just sort of floated through space for a while,
25:32
Speaker 1: and then five billion years ago it started again. So
25:35
Speaker 1: one sense you could think of dark energy is like
25:37
Speaker 1: phase two of the Big Bang. The Big Bang continued,
25:41
Speaker 1: you know, but just when you thought it was safe
25:42
Speaker 1: to get into space, here comes the dark energy, Here
25:45
Speaker 1: comes the Bigger Bang. Yeah, both of them are expansions
25:49
Speaker 1: of space. We think they're probably related, but we don't
25:52
Speaker 1: really know how or why you cannot do the same thing.
25:54
Speaker 1: But who knows why would take a nap for five
25:57
Speaker 1: billion years? That's right, I'm sorry what you do and
26:01
Speaker 1: the time are we getting build for that time? Yeah, exactly.
26:04
Speaker 1: And there are big consequences for the fact that it's
26:06
Speaker 1: not just pushing things through space but actually creating new space. Yeah,
26:10
Speaker 1: because we started a podcast asking like what's going to
26:13
Speaker 1: happen to the universe at the end, and so it
26:16
Speaker 1: has you say, it has big consequences for like what's
26:19
Speaker 1: going to happen to the universe. Yeah, because it's creating
26:22
Speaker 1: new space, which means it's effectively evading the speed limit
26:26
Speaker 1: of the universe, the speed of light. Right, nothing in
26:29
Speaker 1: the universe can move through space faster than the speed
26:31
Speaker 1: of light. All right, that's a hard and fast limit.
26:34
Speaker 1: And so these galaxies can't move through space away from
26:37
Speaker 1: us faster than the speed of light. But there's no
26:41
Speaker 1: limit on how fast you can create new space, the
26:45
Speaker 1: new spaces being created between us and these other galaxies
26:48
Speaker 1: faster than light can go through it. It's like if
26:51
Speaker 1: I was trying to get to you done at Irvine U,
26:54
Speaker 1: and I can only go seventy miles per hour in
26:56
Speaker 1: the highway. You know, nominally you'd be lucky to do that.
27:01
Speaker 1: Let's say it's like two am and have your private
27:05
Speaker 1: Let's say I was using the carpool lane, all right,
27:08
Speaker 1: and uh but yeah, but like let's say that a
27:10
Speaker 1: new land was being created between you and me faster
27:13
Speaker 1: than seventy miles per hour, I would never get to you.
27:15
Speaker 1: That's right. If they're just laying new road and you're
27:18
Speaker 1: faster than you're driving through it, you'll never get down
27:20
Speaker 1: to Irvine, exactly right. And that's the situation. Those photons
27:24
Speaker 1: that are leaving those galaxies now will never reach us
27:27
Speaker 1: because the space in between us is growing faster and
27:30
Speaker 1: the photons go through it right at some point they'll
27:32
Speaker 1: stop reaching us, right like um like, we'll see them,
27:35
Speaker 1: and then suddenly they'll blink out of existence. Exactly things
27:39
Speaker 1: that used to be in our observable universe, things that
27:42
Speaker 1: we see now because light has had a chance to
27:44
Speaker 1: get through the universe to us, will no longer be
27:47
Speaker 1: observable because dark energy is pushing them out of this
27:51
Speaker 1: sphere of the observable universe. All the stuff we can
27:53
Speaker 1: see because light has had a chance to get to us.
27:55
Speaker 1: So galaxies in the sky are disappearing right now, right now,
28:00
Speaker 1: quick rush outside of Things that are on the edge
28:03
Speaker 1: of our observable universe are disappearing because dark energy is
28:06
Speaker 1: pushing them beyond the bounds of things we can see.
28:09
Speaker 1: So the nice guy is getting darker and darker. So
28:11
Speaker 1: like if you hit the fast forward button on a
28:14
Speaker 1: camera point and at the sky, you would see like
28:17
Speaker 1: stars just snuff out, just like yeah, you would see
28:20
Speaker 1: galaxies snuff out of their clusters of stars. And so
28:24
Speaker 1: in that scenario, all these galaxies snuff out of the sky,
28:27
Speaker 1: right they get pushed out beyond our observable horizon and
28:30
Speaker 1: they disappear, And then we're left with the single galaxy
28:34
Speaker 1: in the universe, just like people before Hubble thought, right then,
28:38
Speaker 1: and imagine astronomers in the future, right after all these
28:41
Speaker 1: galaxies are pushed out, They're gonna think we're the only
28:44
Speaker 1: there's only one galaxy in the entire universe. Yeah, because
28:47
Speaker 1: they would be the only thing they could see. Right,
28:49
Speaker 1: It's amazing to imagine, how to to try to think
28:52
Speaker 1: about how could they learn about the universe if all
28:55
Speaker 1: they could see was their galaxy? How could they even
28:57
Speaker 1: possibly know? Right? They would have no how big it
29:00
Speaker 1: actually is. Yeah, they would have no idea what's beyond
29:03
Speaker 1: their observa universe. And that's really humbling because it reminds
29:08
Speaker 1: you of how little we know. Right, we're, after all,
29:11
Speaker 1: fourteen billion years into the history of the universe. There
29:14
Speaker 1: could be fascinating clues about the way the universe works
29:17
Speaker 1: and what it's made out of that have already been
29:19
Speaker 1: pushed beyond our sky that we cannot see and we
29:22
Speaker 1: will never see. Right, So what's lost in the night sky? Well,
29:26
Speaker 1: we have no idea, right there kinds of galaxies? Who
29:30
Speaker 1: knows that we can't see anymore? Yeah, exactly, And continue
29:33
Speaker 1: even further, and remember, dark energy is not just out
29:36
Speaker 1: there in space. It's here, it's with me, it's with you.
29:38
Speaker 1: It's literally pushing me and you apart right now. The
29:41
Speaker 1: reason we don't see it is because we have bonds
29:45
Speaker 1: that are holding us together, right like their dark energy
29:47
Speaker 1: is trying to create new space between the molecules in
29:50
Speaker 1: my hand, But the molecules are bound together tightly enough
29:52
Speaker 1: to resist that. But if dark energy continues, it might
29:56
Speaker 1: eventually shred the Milky Way, right, take our own galaxy
29:59
Speaker 1: and tossed the stars out into space. Eventually we might
30:02
Speaker 1: just be a solar system floating in the inky blackness
30:05
Speaker 1: of space, seeing nothing. Right, that's one potential future, thinking
30:09
Speaker 1: that we're the only star in the entire creation, the
30:13
Speaker 1: entire universe. That's right, that's right, that's one real possibility. Now, again,
30:18
Speaker 1: we don't know what dark energy is gonna do. We
30:20
Speaker 1: don't know if it's strong enough to do that. We
30:21
Speaker 1: don't know if it's gonna stop. We don't know if
30:23
Speaker 1: something else is going to happen. We really have no idea.
30:26
Speaker 1: But it's it's amazing to me that it's only this
30:28
Speaker 1: knowledge is only twenty years old, twenty years ago before
30:31
Speaker 1: we discover the stuff we didn't know that the universe
30:34
Speaker 1: was accelerating, and we didn't know that most of the
30:37
Speaker 1: universe was this thing called dark energy. Like, think about
30:40
Speaker 1: how recent that discovery is. That to me is inspiring
30:43
Speaker 1: because it makes me hope that we have more mind
30:46
Speaker 1: blowing discoveries ahead, you know, more of these moments of
30:48
Speaker 1: like what the universe is totally different from what I imagined.
30:52
Speaker 1: That's what I live for in physics. Well, you know,
31:00
Speaker 1: this is when it give me. Think. This past weekend,
31:02
Speaker 1: I was camping with my kids and my family and
31:06
Speaker 1: it was a beautiful night. You could see all the stars.
31:08
Speaker 1: And I pointed out to my daughter, was like, look
31:11
Speaker 1: at all the stars. And I was pointing out some
31:13
Speaker 1: of the constellations and stuff, and she's like wow. And
31:16
Speaker 1: I talked pointed out the Big Dipper and she's like,
31:19
Speaker 1: that's the Big Dipper. And she proceeded to tell me
31:22
Speaker 1: this whole complicated story about the Big Dipper that she
31:24
Speaker 1: read in this book she had at school that she's
31:27
Speaker 1: read like a million times, but for the first time
31:30
Speaker 1: she had actually seen the stars, She had actually seen
31:33
Speaker 1: the Big Dipper. What a fun moment for her. Yeah,
31:36
Speaker 1: to make to make these things real yeah, yeah, and
31:39
Speaker 1: so yeah, so I think that's a big lesson. You know,
31:41
Speaker 1: go out there, look at the stars before they go away.
31:45
Speaker 1: And this is not abstract. I mean, this is our
31:47
Speaker 1: universe we're actually talking about. And you can go along
31:49
Speaker 1: and live your life and worry about traffic and paying
31:52
Speaker 1: the next bill in your own financial big bang. But
31:54
Speaker 1: these things are our context, right, This is the universe
31:57
Speaker 1: we live in that we're definitely trying to discover before
31:59
Speaker 1: it blow was itself up. It's changing all the time,
32:02
Speaker 1: so go out there and experience it. Absolutely. If you
32:11
Speaker 1: still have a question after listening to all these explanations,
32:14
Speaker 1: please drop us a line. We'd love to hear from you.
32:17
Speaker 1: You can find us at Facebook, Twitter, and Instagram at
32:20
Speaker 1: Daniel and Jorge that's one word, or email us at
32:24
Speaker 1: Feedback at Daniel and Jorge dot com.