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