Latest / Daniel and Kelly’s Extraordinary Universe / What Is The Emptiest Place In The Universe?

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What Is The Emptiest Place In The Universe? · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: Hey, Daniel, I've kind a dumb question. Oh, those are
• 0:09
  Speaker 1: always the hardest questions to answer. Why is it hard
• 0:13
  Speaker 1: to come with a dumb answer? He said, You know,
• 0:16
  Speaker 1: what people call dumb questions are sometimes really simple, deep questions,
• 0:20
  Speaker 1: and those are the hardest but sometimes the most fun
• 0:22
  Speaker 1: to tackle. Okay, here's my dumb question, Daniel. Where where
• 0:26
  Speaker 1: does space start? You know, like, technically we are in space,
• 0:29
  Speaker 1: but we don't think of ourselves in space. We're sort
• 0:31
  Speaker 1: of on Earth. There's an official definition a hundred kilometers up.
• 0:34
  Speaker 1: That's the official beginning of space and stuff, and that
• 0:37
  Speaker 1: sounds totally made up because it's a perfectly round number.
• 0:41
  Speaker 1: All right, Well, I guess the question is what is
• 0:44
  Speaker 1: a space? Right? It's it's kind of like when you
• 0:46
  Speaker 1: no longer have air, or when there's a vacuum. Yeah, exactly.
• 0:50
  Speaker 1: It's you know, when you're out there, like deep into space,
• 0:52
  Speaker 1: you know, when you're not there here on Earth, and
• 0:55
  Speaker 1: the boundary between them is it's a bit funny, you know,
• 0:57
  Speaker 1: it's sort of like growing up. You know, officially you're
• 1:01
  Speaker 1: grown up on you turn a team, but it's not
• 1:02
  Speaker 1: like a moment when you suddenly get wisdom and context
• 1:07
  Speaker 1: and vision and understanding and perspective, and you can make
• 1:10
  Speaker 1: grown up decisions. You know. It's something that very slowly happens.
• 1:13
  Speaker 1: Well Offecially, the government does give you a certificate in
• 1:15
  Speaker 1: your a team. That's right, Please register for the army. Congratulations,
• 1:20
  Speaker 1: I'm being an adult. Yeah, you saying technically, I I'm
• 1:23
  Speaker 1: I haven't grown up like technically you may. You may
• 1:25
  Speaker 1: never grow up. That's right. You and Peter Pan are
• 1:28
  Speaker 1: officially not grown up. There you go, Peter Pan, the
• 1:31
  Speaker 1: first thats wrong? That's probably truck too. H I am
• 1:52
  Speaker 1: or Hey, I'm a cartoonist and the creator of PhD Comics. Hi.
• 1:55
  Speaker 1: I'm Daniel Whitson. I'm a part of the physicist I
• 1:58
  Speaker 1: work at certain smashing stuff together to reveal the secrets
• 2:01
  Speaker 1: of the universe. And I am not a cartoonist. That's right. Also,
• 2:04
  Speaker 1: I forgot to mention, I'm also not if this isis
• 2:06
  Speaker 1: but in any case, welcome to our podcast Daniel and
• 2:09
  Speaker 1: Jorge Explained the Universe, a production of I Heart Radio
• 2:12
  Speaker 1: where we explain all the crazy and amazing things that
• 2:15
  Speaker 1: are out there in the universe and we have long
• 2:18
  Speaker 1: conversations about it. That's right. We're gonna take a mind
• 2:21
  Speaker 1: blowing tour of all the crazy stuff out there in
• 2:23
  Speaker 1: the universe. And the most important thing is that we're
• 2:25
  Speaker 1: going to do our best to explain in a way
• 2:27
  Speaker 1: that actually makes sense to you and hopefully entertains you
• 2:30
  Speaker 1: along the way. I mean, where else can you sit
• 2:32
  Speaker 1: for an hour and hear about nothing? Literally nothing? That's right.
• 2:36
  Speaker 1: We are going to get spacey today, folks. That's right.
• 2:39
  Speaker 1: Today on the program, we're gonna be asking the question
• 2:46
  Speaker 1: can space be empty? Truly empty? Like nothing? That's right?
• 2:51
  Speaker 1: What's actually out there in space? If you went out
• 2:54
  Speaker 1: into space and you like grabbed a big box and
• 2:57
  Speaker 1: and closed up some space, what would you capture? Is
• 3:00
  Speaker 1: space pretty empty? Is it mostly full of stuff that's invisible?
• 3:03
  Speaker 1: What's going on out there in space? And you can
• 3:06
  Speaker 1: think of this question for those of you keeping track
• 3:08
  Speaker 1: at home as part of our Extreme Universe series, This
• 3:12
  Speaker 1: one sort of like what is the emptiest place in
• 3:15
  Speaker 1: the universe? Where in the universe is space? The space
• 3:19
  Speaker 1: is yeah, I think most importantly, can it be empty?
• 3:22
  Speaker 1: Like is it possible to have nothingness in space? That's right? Yeah,
• 3:26
  Speaker 1: And that's a fun question too, like do you mean
• 3:28
  Speaker 1: experimentally like could we build something which makes a cubic
• 3:32
  Speaker 1: meter of truly empty space? Or theoretically, like is it
• 3:36
  Speaker 1: is it against the laws of physics for space to
• 3:38
  Speaker 1: be empty? Yeah? Or I mean just are there's are
• 3:41
  Speaker 1: there spots out there in the huge universe that we
• 3:43
  Speaker 1: live in that are really truly empty? Do you know
• 3:46
  Speaker 1: what I mean? Like we know that you know that
• 3:48
  Speaker 1: we know the stuff right here on Earth, on on
• 3:50
  Speaker 1: this planet, but are there parts of the universe where
• 3:53
  Speaker 1: there's truly nothing in there? That's right? Because the universe
• 3:56
  Speaker 1: is huge, it certainly a lot of space out there, right,
• 3:59
  Speaker 1: and not that much stuff. You know, you just look
• 4:01
  Speaker 1: up at the night sky and it's mostly space, right,
• 4:04
  Speaker 1: There's not that many stars, even if you have a
• 4:06
  Speaker 1: really amazing telescope because he really really far away, there's
• 4:09
  Speaker 1: a lot more space than stars. And so that makes
• 4:12
  Speaker 1: me wonder, and I think other people wonder, like what's
• 4:14
  Speaker 1: in that space? How empty is it? How much stuff
• 4:18
  Speaker 1: is there in space? How spacey is space? How spacious?
• 4:22
  Speaker 1: I think maybe the question is how spacious is space?
• 4:25
  Speaker 1: How spacious in space? Exactly? Is there room for me
• 4:28
  Speaker 1: to move out there and like really spread out with
• 4:30
  Speaker 1: my stuff? You got a lot of stuff in storage.
• 4:32
  Speaker 1: You're gonna take out an unpack, right, Yeah. And we
• 4:35
  Speaker 1: have had podcasts about how big the universe is, right,
• 4:38
  Speaker 1: and what's the biggest thing in the universe, But this
• 4:41
  Speaker 1: is the first time we're asking can't space actually be empty? Yeah? Exactly?
• 4:44
  Speaker 1: How empty is it? So as usual, before we dig
• 4:48
  Speaker 1: into the topic, I thought I would crowdsource of information,
• 4:50
  Speaker 1: and I walked around the UC Irvine campus and I
• 4:53
  Speaker 1: asked people, what do you think would be in a
• 4:55
  Speaker 1: random cubic meter of space? How empty is it? Is
• 4:58
  Speaker 1: there stuff out there? Or is it mostly empty? Yeah?
• 5:01
  Speaker 1: So thank for a moment before you hear the answers,
• 5:04
  Speaker 1: and ask yourself if you encountered a random physicist on
• 5:07
  Speaker 1: the street and they asked you, what do you think
• 5:09
  Speaker 1: is in a one cubic meter of space? What would
• 5:12
  Speaker 1: you answer? Here's what people had to say, what's in
• 5:15
  Speaker 1: a random cubic meter of empty space? Do you think of? Adams? Adams?
• 5:21
  Speaker 1: That's all I can think of. Jeez, I'm not too sure. Um,
• 5:29
  Speaker 1: I don't know. I know that the particles is what
• 5:31
  Speaker 1: I'd assume, cubic million, moleculous, preaky million. I don't know.
• 5:42
  Speaker 1: Guessing it depends where you're on. I mean, if you're
• 5:44
  Speaker 1: out in space, it'll just be filled with space. I
• 5:47
  Speaker 1: mean if it's space is empty, then there's nothing. I'm
• 5:49
  Speaker 1: assuming of the matter. We know, probably nothing, but there
• 5:54
  Speaker 1: could be dark energy and that cubic meter or dark
• 5:59
  Speaker 1: dark matter. Cool third reaffraightation. Awesome, thanks very much, dark matters,
• 6:04
  Speaker 1: dark quarters, dark matter, and yeah, I mean I'll watchally
• 6:08
  Speaker 1: all dark matter. What about like far between galaxies? Um,
• 6:13
  Speaker 1: is the dark matter everywhere? Or is it just near
• 6:15
  Speaker 1: the galaxies? No, it's I think it's like every open space.
• 6:19
  Speaker 1: You're like like in between like planets and stars and cool,
• 6:23
  Speaker 1: all right, I would say that there's stuff in there.
• 6:26
  Speaker 1: I wouldn't say it was like completely empty space. It's
• 6:28
  Speaker 1: probably a bunch of its particles or components of something.
• 6:32
  Speaker 1: I would say, okay, dust, there are different types of particles.
• 6:37
  Speaker 1: Is it totally empty? Vacuum energy? I guess all right, cool,
• 6:41
  Speaker 1: you'd probably get some particles of some swords like how
• 6:45
  Speaker 1: many holding up to like eight grade science? Al Right?
• 6:50
  Speaker 1: I like, I like, um, most people just said stuff
• 6:54
  Speaker 1: like I feel like, did you just say maybe? I mean,
• 6:58
  Speaker 1: you couldn't just say the Big Bang that would have
• 7:00
  Speaker 1: in it physics remnants of the Big Bang. I mean
• 7:04
  Speaker 1: that's always correct, but stuff is also pretty versatile as
• 7:07
  Speaker 1: as a physics answer. Well, that's sort of the question
• 7:09
  Speaker 1: is space have any stuff in it? And so if
• 7:12
  Speaker 1: you want to make it binary, like you know it's
• 7:15
  Speaker 1: empty or there's stuff and it, then these people were
• 7:16
  Speaker 1: voting for stuff. I think a lot of people have
• 7:19
  Speaker 1: the sense that space is not truly empty, that there's
• 7:21
  Speaker 1: always something in there, even if you can't see it. Oh,
• 7:24
  Speaker 1: I see you're saying that most people didn't say nothing
• 7:29
  Speaker 1: or vacuum. Do you know what I mean? Like, most
• 7:32
  Speaker 1: people assumed that they had stuff in it. Yeah, exactly.
• 7:35
  Speaker 1: That was the sense that I got from most people
• 7:37
  Speaker 1: that they weren't quite sure what was in there. They
• 7:39
  Speaker 1: thought it was mostly empty, but not truly empty. There
• 7:42
  Speaker 1: was still some residual stuff in there. So if you're
• 7:45
  Speaker 1: giving a test annual in a student, you as like, um, hey,
• 7:49
  Speaker 1: what is quantum physics? And the student writes stuff, what
• 7:53
  Speaker 1: would you would you taken a clean market wrong? Oh
• 7:56
  Speaker 1: for sure, yeah, but I always give credit. Um, I
• 7:58
  Speaker 1: always have a lot of partial it and you always
• 8:00
  Speaker 1: get some points for writting down anything like even stray
• 8:03
  Speaker 1: pencil marks. I will get partial credit for sometimes really,
• 8:07
  Speaker 1: because when it's when they leave the space empty that
• 8:10
  Speaker 1: you really bothers you exactly pure empty space that bothers me.
• 8:14
  Speaker 1: For that, you get a zero right reflecting the amount
• 8:17
  Speaker 1: of effort you put into the problem. But you write
• 8:19
  Speaker 1: down something anything, um, I'll give you some points. Maybe
• 8:22
  Speaker 1: you didn't know this. At the end of all of
• 8:24
  Speaker 1: my mid terms, I also do a physics cartoon contest. Really, yeah,
• 8:28
  Speaker 1: what do you mean? I pick a random cartoon from
• 8:31
  Speaker 1: the New Yorker, usually that looks a little physically like
• 8:34
  Speaker 1: there's a wheel or something physically in it, and I
• 8:37
  Speaker 1: asked them to write a physics related caption for that
• 8:41
  Speaker 1: cartoon related to what they learned on the exam. Well,
• 8:44
  Speaker 1: hopefully they didn't learn it on the exam hopefully before
• 8:48
  Speaker 1: for yeah. And then I have the ta tas always
• 8:52
  Speaker 1: created and I tell them if they write anything, give
• 8:54
  Speaker 1: them a point. If they write something that actually makes
• 8:57
  Speaker 1: you laugh, give them two points. And you know, sometimes
• 9:01
  Speaker 1: these kids are pretty funny. I can imagine being stress
• 9:03
  Speaker 1: stressed out student thinking, oh my gosh, should I devote
• 9:06
  Speaker 1: my last two minutes of trying to come up with
• 9:07
  Speaker 1: a clever caption, or should I try to solve this
• 9:10
  Speaker 1: quantum physics problem. Well, I hope it will get more pointive.
• 9:14
  Speaker 1: I hope you give them a little bit of stress relief.
• 9:16
  Speaker 1: But it's actually some interesting stuff in the physics education
• 9:19
  Speaker 1: literature that shows that making people think about the the
• 9:23
  Speaker 1: about physics in the context of their real lives or
• 9:26
  Speaker 1: in real life contexts helps them understand these concepts. So
• 9:29
  Speaker 1: it's not just a joke on my part. It's like,
• 9:31
  Speaker 1: I really think that it helps them understand. They have
• 9:34
  Speaker 1: to think about, how is this relevant to some situation?
• 9:37
  Speaker 1: Oh interesting, haven't kind of take a step back and
• 9:41
  Speaker 1: try to find a think about the context of the
• 9:44
  Speaker 1: stuff they learned. Yeah, exactly exactly, because we don't learn
• 9:47
  Speaker 1: everything in the vacuum, right, it's not just out there
• 9:49
  Speaker 1: floating in space. Right. Well, now, now I'm a little
• 9:52
  Speaker 1: nervous for the universe. I feel like if the universe
• 9:54
  Speaker 1: is truly can be truly empty, you might give it
• 9:57
  Speaker 1: zero points, no partial. Well, you know the universe is
• 10:01
  Speaker 1: making it ever um talking about being truly empty. When
• 10:05
  Speaker 1: I was doing some reading for this episode, I was
• 10:07
  Speaker 1: shocked to discover some things about what we consider empty
• 10:10
  Speaker 1: space here on Earth. You know, here on Earth, we
• 10:13
  Speaker 1: can do things that create vacuum in the lab, right,
• 10:17
  Speaker 1: people do this to to do all sorts of experiments,
• 10:19
  Speaker 1: and we have pretty good vacuum for example, the large
• 10:21
  Speaker 1: age on collider where we smash protons together. We suck
• 10:24
  Speaker 1: all the other stuff out because we don't want it
• 10:26
  Speaker 1: to interfere with the collisions. But it turns out that
• 10:28
  Speaker 1: that vacuum is not really empty like at all. If
• 10:32
  Speaker 1: you look at the density of air that we're breathing,
• 10:35
  Speaker 1: like the air that I'm breathing right now, there's about
• 10:38
  Speaker 1: ten to the twenty five molecules per cubic meter. So
• 10:42
  Speaker 1: that's a huge number, right, like ten with twenty five zeros.
• 10:45
  Speaker 1: I don't even know what the scientific prefixes for like.
• 10:48
  Speaker 1: And it's all like air molecules and gas molecules. And
• 10:53
  Speaker 1: and when they when they make vacuum, they pump the
• 10:56
  Speaker 1: air out, right, they suck it all out. Sometimes they
• 10:58
  Speaker 1: even bake it to try to get as much the
• 11:00
  Speaker 1: air out of it as possible. And you'd imagine they
• 11:02
  Speaker 1: maybe they get it down to really pretty good vacuum.
• 11:05
  Speaker 1: But what they call like ultra high vacuum in the
• 11:07
  Speaker 1: lab still has like ten to the twelve or ten
• 11:11
  Speaker 1: to the fifteen particles per cubic meter, which is still
• 11:14
  Speaker 1: a huge number, right, I mean it's a much smaller number.
• 11:17
  Speaker 1: You're down like ten or fifteen orders of magnitude, but
• 11:22
  Speaker 1: super high vacuum here on Earth is filled with particles.
• 11:26
  Speaker 1: What do you think is a limitation? Why can't they
• 11:28
  Speaker 1: suck out those last few particles? I mean last few
• 11:31
  Speaker 1: by me, I mean the last ten to the fifteen
• 11:33
  Speaker 1: part exactly. It's difficult. You know, you've gotta have really
• 11:36
  Speaker 1: powerful pumps, and you've gotta have no leaks. You know,
• 11:39
  Speaker 1: it's really pretty tricky. It's hard to get nothingness, like
• 11:43
  Speaker 1: to pull everything out of a space, yeah, because the
• 11:45
  Speaker 1: pressure on it is tremendous. Right, If there's nothing in it,
• 11:49
  Speaker 1: then things are pressing on it from all sides, and
• 11:51
  Speaker 1: then there's nothing in it to push back, right, So
• 11:53
  Speaker 1: things are trying to squeeze in everywhere. So you have
• 11:55
  Speaker 1: like the tiniest little gap, like an atom sized gap
• 11:58
  Speaker 1: in your in your well did seem or something, and
• 12:01
  Speaker 1: particles are going to find their way through. It's a
• 12:03
  Speaker 1: very powerful pressure from the outside, and you know, vacuums
• 12:07
  Speaker 1: don't suck, right, It's not like the vacuum inside this
• 12:10
  Speaker 1: machine is like actively sucking stuff in. It's all the
• 12:13
  Speaker 1: air outside that's pressing down, that's pushing in. Wait, what
• 12:16
  Speaker 1: do you mean it's not the vacuum. Well, you can
• 12:20
  Speaker 1: think about it in two ways, but I never like
• 12:22
  Speaker 1: thinking about the vacuum is like actively sucking stuff in.
• 12:24
  Speaker 1: It's not like there's something inside a vacuum chamber that's
• 12:27
  Speaker 1: going right. The reason things like things get sucked into
• 12:33
  Speaker 1: a vacuum, it's not like a black hole black holes
• 12:35
  Speaker 1: actively pulling stuff in. The reason things um rush into
• 12:39
  Speaker 1: a vacuum is because the air is being pressed into it. Right. Well,
• 12:45
  Speaker 1: you know, my grandma used to say, nature abhorts a vacuum.
• 12:48
  Speaker 1: Did your grandma invent that? Right? I think she invented that.
• 12:51
  Speaker 1: I'm not quite sure, but she used to say it. All.
• 12:53
  Speaker 1: My grandma used to say, I think therefore, I am wow,
• 12:58
  Speaker 1: that is still original. Over they are Our grammars were contemporaries,
• 13:04
  Speaker 1: geniuses of modern philosophy. She said, she ab pours vacuuming.
• 13:08
  Speaker 1: I'm not quite sure which one, probably probably the ladder. Okay, sorry, yeah,
• 13:15
  Speaker 1: exactly say you're in a spaceship, right and there's a leak, right,
• 13:23
  Speaker 1: then is the vacuum sucking all the air out of
• 13:26
  Speaker 1: the ship. No, it's the air and the ship is
• 13:28
  Speaker 1: like a balloon. It's under high pressure and you get
• 13:30
  Speaker 1: a leak and the air is pushing itself out. Right.
• 13:33
  Speaker 1: So the reason when you when they open the airlock
• 13:36
  Speaker 1: on a spaceship on a movie and you get that
• 13:38
  Speaker 1: tremendous wind, it's not the space sucking the air out
• 13:41
  Speaker 1: of the spaceship. It's the air pushing itself out because
• 13:44
  Speaker 1: it's under pressure. Okay, So we're talking about space and
• 13:48
  Speaker 1: whether space can be truly empty, right, and so the
• 13:52
  Speaker 1: question it is space like the perfect vacuum. Is there
• 13:55
  Speaker 1: really nothing out there? And the point I wanted to
• 13:57
  Speaker 1: make was that even super good vacuums here on Earth
• 13:59
  Speaker 1: are pretty terrible when it comes to when it comes
• 14:02
  Speaker 1: to relationships to space. So I just wanted to set
• 14:04
  Speaker 1: that stage right that we're gonna be talking about a
• 14:07
  Speaker 1: certain number of molecules per per cubic meter and the
• 14:10
  Speaker 1: air you breathe. This tend to the twenty five molecules
• 14:13
  Speaker 1: per cubic meter and the air and a super awesome,
• 14:15
  Speaker 1: fancy vacuum is like ten to the twelve particles per
• 14:18
  Speaker 1: cubic meter. Okay, so that that that's like the goal
• 14:22
  Speaker 1: you're saying, that's the gold standards for vacuum nows here
• 14:25
  Speaker 1: on Earth. That's right, Yeah, in terms of human engineering exactly. Yeah.
• 14:29
  Speaker 1: And um, so so let's take a tour, right, Let's
• 14:32
  Speaker 1: go up from the planet and think about and explore
• 14:36
  Speaker 1: space and and talk about how much stuff there is
• 14:38
  Speaker 1: in space as we leave the Earth, because the fascinating
• 14:41
  Speaker 1: thing to me is the amount of stuff in space.
• 14:43
  Speaker 1: The emptiness of space changes where you're depending on where
• 14:47
  Speaker 1: you are in space. So the answer to the question
• 14:51
  Speaker 1: is can space be empty you're saying, changes depending on
• 14:55
  Speaker 1: on where you are. Yeah, there's different levels of spaces. Yeah,
• 14:59
  Speaker 1: different levels of spaciness exactly. So for example, um, let's
• 15:03
  Speaker 1: dig into it. Like, if you take off from the
• 15:05
  Speaker 1: Earth and you leave the Earth's atmosphere and you're out
• 15:08
  Speaker 1: in space, then you're you're in this extended region we
• 15:11
  Speaker 1: call the heliosphere, which is where the Sun dominates and
• 15:15
  Speaker 1: the Sun is pumping out particles all the time. We
• 15:18
  Speaker 1: call it the solar wind. So yeah, you're far away
• 15:20
  Speaker 1: from the Earth's atmosphere, but you're in this region of
• 15:22
  Speaker 1: space that's filled with particles streaming from the Sun. And
• 15:27
  Speaker 1: that's basically the entire Solar system, right, I mean, basically
• 15:31
  Speaker 1: the entire Solar System is kind of within the heliosphere. Yeah, exactly,
• 15:35
  Speaker 1: the entire Solar system. And if you look, if you
• 15:37
  Speaker 1: Google image search heliosphere, you'll see that the heliosphere is
• 15:41
  Speaker 1: much bigger than like even the orbit of Pluto, because
• 15:44
  Speaker 1: the soul of the Sun dominates the local environment. At
• 15:47
  Speaker 1: some point, Peter's out and like the magnetic fields inside
• 15:50
  Speaker 1: the galaxy start to take over. But in the environment
• 15:53
  Speaker 1: around the Sun, you know, the the space in our
• 15:56
  Speaker 1: Solar system is dominated by the solar wind, and the
• 15:59
  Speaker 1: solar wind has all these particles that come from the
• 16:02
  Speaker 1: outer level of plasma of the Sun, which is obviously
• 16:04
  Speaker 1: glowing hot and shooting out light, but also shooting out
• 16:08
  Speaker 1: electrons and protons and other kind of radiation. So you're
• 16:11
  Speaker 1: saying the space in between planets, like between here and Mars,
• 16:16
  Speaker 1: here and Jupiter here in the Sun, it's not empty
• 16:19
  Speaker 1: at all. It's like it's full of sunweather exactly. It's
• 16:22
  Speaker 1: full of solar weather and it's about five to ten
• 16:26
  Speaker 1: million protons per cubic meter, which is still you know,
• 16:29
  Speaker 1: a hundred or a thousand times better than the vacuum
• 16:33
  Speaker 1: chambers we have on Earth. But it's not in zero.
• 16:36
  Speaker 1: So you said protons. Are you saying protons mostly because
• 16:38
  Speaker 1: that's that's those are matter particles? Yeah, exactly. Well, the
• 16:41
  Speaker 1: solar wind is mostly electrons and protons and a few
• 16:45
  Speaker 1: other kinds of particles, but mostly it's it's it's those
• 16:48
  Speaker 1: protons and electrons, and so you count them in turn.
• 16:50
  Speaker 1: And the protons are much heavier than the electrons, so
• 16:52
  Speaker 1: they dominate the calculation. Oh, I see they count of stuff,
• 16:56
  Speaker 1: but like photons, and do they count it stuff photons?
• 16:58
  Speaker 1: Do photons counts stuff? Hmm, that's a good question. Um.
• 17:02
  Speaker 1: You know, later when we talk about what's in in between,
• 17:06
  Speaker 1: like superclusters of galaxies and all we have is energy,
• 17:10
  Speaker 1: then I think you'll have to count that. Um. But
• 17:12
  Speaker 1: you know, photons are not matter there they are radiation though.
• 17:16
  Speaker 1: That's a great good question. So you're saying, within the
• 17:20
  Speaker 1: Solar system, the space is still not empty, it's full.
• 17:23
  Speaker 1: It's still full of stuff from the Sun. That's right,
• 17:25
  Speaker 1: And we should remember that all the stuff that we
• 17:28
  Speaker 1: know about everything that's made of atoms, right, that's a
• 17:31
  Speaker 1: little fraction of the universe. Right, that's only five of
• 17:35
  Speaker 1: all the energy in the universe, and it's about twenty
• 17:38
  Speaker 1: of all the matter. The stuff in the universe. The
• 17:40
  Speaker 1: rest of it is dark matter, and we and dark
• 17:43
  Speaker 1: matter normal matter both cluster into structures like you know,
• 17:46
  Speaker 1: planets and galaxies. Whenever those are the structures of normal matter,
• 17:50
  Speaker 1: dark matter follows those. So basically you can think of
• 17:53
  Speaker 1: it like anywhere you see blobs of matter, there's also
• 17:56
  Speaker 1: dark matter there, and about five times as much. So
• 18:00
  Speaker 1: there's five million protons, you're saying, there's probably twenty five
• 18:04
  Speaker 1: million amount of stuff of dark matter in that in
• 18:08
  Speaker 1: that space between planets. Yeah, and then we don't know
• 18:11
  Speaker 1: a whole lot about the structure of dark matter. We
• 18:13
  Speaker 1: know clumps at the center of the galaxy and then
• 18:15
  Speaker 1: spreads out. We don't know how clumpy it is, if
• 18:18
  Speaker 1: it's pretty smooth or if it's not. But on average, yeah,
• 18:21
  Speaker 1: you can just take the amount of matter and multiplied
• 18:23
  Speaker 1: by five, and that's a pretty good estimate for how
• 18:25
  Speaker 1: much dark matter there is. Like in this room with
• 18:27
  Speaker 1: me right now, you know, in the air I'm breathing,
• 18:30
  Speaker 1: there's what ten to the twenty five molecules of air
• 18:34
  Speaker 1: right that much mass, there's five times as much dark
• 18:37
  Speaker 1: matter in this room per cubic meter with me right now,
• 18:40
  Speaker 1: And the same is true out in space. Dark matter
• 18:43
  Speaker 1: follows the normal matter. So you can basically just multiply
• 18:45
  Speaker 1: the normal matter by five and it tells you how
• 18:47
  Speaker 1: much dark matter there is. So there's still a lot
• 18:50
  Speaker 1: of stuff out there in the Solar System. The space
• 18:54
  Speaker 1: is not quite into but it's sort of really empty
• 18:56
  Speaker 1: compared to what we can do on Earth, right, Like
• 18:58
  Speaker 1: you're saying, here on Earth, we can you tend, but
• 19:01
  Speaker 1: you're staying out in between the Solar System, between planets.
• 19:05
  Speaker 1: It's about tend to the six tend to the six,
• 19:07
  Speaker 1: which is much better than vacuums on Earth. But it's
• 19:10
  Speaker 1: not that small. And in fact, if you're an astronaut
• 19:12
  Speaker 1: you need you need like really really good sunscreen because
• 19:16
  Speaker 1: it's enough radiation to fry you and give you cancer
• 19:18
  Speaker 1: pretty quickly. So the fact that it's not empty has consequences.
• 19:22
  Speaker 1: Oh you're saying, if it if it was, if you
• 19:26
  Speaker 1: were just out there in a very really thin space,
• 19:29
  Speaker 1: suit without a whole lot of protection from radiation, you
• 19:32
  Speaker 1: would get fried from that radiation. Wow. So the fact
• 19:36
  Speaker 1: that it is pretty empty means that you feel those
• 19:39
  Speaker 1: that light from the Sun a lot stronger. Exactly. We
• 19:43
  Speaker 1: have an atmosphere between us and the Sun that protects
• 19:45
  Speaker 1: us from the solar wind. Right, the solar wind doesn't
• 19:47
  Speaker 1: come down to the surface because we're protected by the
• 19:49
  Speaker 1: buff or the atmosphere. But out in space you're not
• 19:51
  Speaker 1: shielded by that, and so you feel the full brunt
• 19:54
  Speaker 1: of the solar solar radiation. And uh, yeah, it's dangerous stuff.
• 19:58
  Speaker 1: It's dangerous stuff, is it? There's stuff out there and
• 20:01
  Speaker 1: it can kill you. Right, you'll run through traffic, folks.
• 20:05
  Speaker 1: It should be the title, right next book, can you
• 20:08
  Speaker 1: space traffic? All this stuff they can kill you. Space
• 20:11
  Speaker 1: can kill you. Well, let's let's take off from the
• 20:15
  Speaker 1: Solar System and let's go into interstellar space. But first
• 20:18
  Speaker 1: let's take a quick break. All right, we're talking about
• 20:33
  Speaker 1: how empty is space, and we we learned that um
• 20:37
  Speaker 1: that inner inner planetary space, like between us and other
• 20:41
  Speaker 1: planets in our Solar system, is pretty empty, but not
• 20:43
  Speaker 1: quite empty. Right, there's still millions of millions of protons
• 20:46
  Speaker 1: and stuff in like a cubic meter of space, right,
• 20:50
  Speaker 1: and there's a lot of cubic meters in that space.
• 20:52
  Speaker 1: So you're talking a huge amount of particles, Like if
• 20:55
  Speaker 1: you have to count them or number them or name them,
• 20:57
  Speaker 1: I mean, it's it's too big a number to really
• 20:59
  Speaker 1: think about, which, which is sort of strange, is cognitively
• 21:02
  Speaker 1: dissended from the fact that we think of it is empty. Right,
• 21:05
  Speaker 1: So remember it's just like chok full of particles, right,
• 21:08
  Speaker 1: It's like you're swimming in protons and stuff exactly, You're
• 21:12
  Speaker 1: literally swimming in it um. But then once you leave
• 21:15
  Speaker 1: our Solar system, you go past the heliosphere, and only
• 21:18
  Speaker 1: a couple of man made objects have ever done this,
• 21:20
  Speaker 1: like the Voyager probes. They've been traveling for decades and
• 21:23
  Speaker 1: they finally broke past into like the inter interstellar space,
• 21:28
  Speaker 1: like the stuff that the galaxy is made out of.
• 21:30
  Speaker 1: So you're saying that the stuff that comes out from
• 21:32
  Speaker 1: the Sun, all those protons and ions and stuff, at
• 21:35
  Speaker 1: some point kind of doesn't go on forever, right, like
• 21:39
  Speaker 1: they maybe they come back because of gravity. Is that
• 21:41
  Speaker 1: is that kind of what happens, Like they cluster around
• 21:43
  Speaker 1: the Solar system. Well, they Peter out there at the
• 21:46
  Speaker 1: intensity gets less and less just because the volume gets
• 21:49
  Speaker 1: larger and larger um. And then also they hit the
• 21:52
  Speaker 1: interstellar magnetic field, right, what, there's magnetic fields inside the
• 21:57
  Speaker 1: galaxy you mean, And and that's different than the one
• 21:59
  Speaker 1: we feel inside the solar system. Yeah, because our solar system,
• 22:03
  Speaker 1: the magnetic field is dominant by the magnetic field of
• 22:05
  Speaker 1: the Sun. Right, And the same way the Earth's magnetic
• 22:08
  Speaker 1: field also helps shield us from the solar wind, right,
• 22:12
  Speaker 1: the Sun's magnetic field helps shield us from like the
• 22:15
  Speaker 1: galactic wind. Whoa h yeah exactly. But then if Peter's
• 22:20
  Speaker 1: out right, and you're no longer really protected by the
• 22:22
  Speaker 1: Sun's magnetic field, where the point where the Sun's magnetic
• 22:25
  Speaker 1: field is about as strong as the magnetic field of
• 22:27
  Speaker 1: the galaxy, right, and you're really really far away, and
• 22:30
  Speaker 1: so the density of these particles the solar wind is dropping.
• 22:34
  Speaker 1: That's when we say you're you're in the interstellar space.
• 22:36
  Speaker 1: You've left the heliosphere. So who gives you a certificate
• 22:40
  Speaker 1: that at that point you can make your own certificate,
• 22:45
  Speaker 1: because you can do anything, because you've accomplished something nobody's
• 22:48
  Speaker 1: ever done before. Just bring your own printer and print
• 22:51
  Speaker 1: yourself a little certificate. Well, that's probably where the you know,
• 22:55
  Speaker 1: our our alien overlords are waiting for us. Oh, I see,
• 22:58
  Speaker 1: so you're saying that they're just waiting to I ne
• 23:00
  Speaker 1: something as as we step out there. Yeah. Sometimes I
• 23:03
  Speaker 1: think that the reason we've never heard from alien species
• 23:05
  Speaker 1: is that they're running some massive cosmic zoo, you know,
• 23:08
  Speaker 1: and they're just out there watching us, laughing at all
• 23:10
  Speaker 1: of our antics. And then all we need to do
• 23:13
  Speaker 1: to figure that out and just get out there and
• 23:15
  Speaker 1: say hello. And maybe they're like hanging out there waiting
• 23:17
  Speaker 1: for us to um, you know, get far enough away
• 23:19
  Speaker 1: from our planet that we're really talking to you. They're
• 23:22
  Speaker 1: just waiting for us to get put us back into
• 23:24
  Speaker 1: our cages. Is that don't make me use the house
• 23:29
  Speaker 1: exactly again for the first time. Um. So, if you
• 23:36
  Speaker 1: do get out there, if you do get out there
• 23:39
  Speaker 1: past our solar system in the in the area dominated
• 23:42
  Speaker 1: by the Sun, then you're in what we call the
• 23:44
  Speaker 1: interstellar medium. And this is mostly gas. It's like gas
• 23:48
  Speaker 1: and a little bit of dust in some cosmic rays. Okay,
• 23:51
  Speaker 1: what's the difference between gas and dust? Is it that
• 23:54
  Speaker 1: like more complex atoms and stuff. Yeah, dust is like
• 23:57
  Speaker 1: pulverized rock, right, So you have the stuff from the
• 24:01
  Speaker 1: inside of supernova and old planets that got destroyed and whatever,
• 24:05
  Speaker 1: and so yeah, you have like metals and and all
• 24:08
  Speaker 1: the silicates and all sorts of stuff. That's what dust is.
• 24:11
  Speaker 1: Gas is masic, just hydrogen, right, most of the most
• 24:14
  Speaker 1: of the universe is gas, and most of that is hydrogen.
• 24:16
  Speaker 1: So it's a proton with electron whizzing around it. Well,
• 24:19
  Speaker 1: and what's the concentration at that point? It actually varies
• 24:22
  Speaker 1: a lot once you get out of the Solar System
• 24:24
  Speaker 1: past the heliosphere. At the high end it's about a
• 24:27
  Speaker 1: million molecules per cubic meter, which is just a little
• 24:30
  Speaker 1: lower than the density inside the Solar System. But then
• 24:33
  Speaker 1: at the low end it goes down to about a
• 24:35
  Speaker 1: hundred particles per cubic meter. It's because the galaxy is
• 24:38
  Speaker 1: just not that smooth right there, like hot spots and
• 24:40
  Speaker 1: cold spots, the spots where it's more dense and spots
• 24:43
  Speaker 1: where it's less dense. So it varies between like a
• 24:46
  Speaker 1: hundred and a million molecules per cubic meter. In the
• 24:49
  Speaker 1: interstellar medium, the spaces between solar systems. Well, here's here's
• 24:54
  Speaker 1: a question. How do we know what spaces like out
• 24:56
  Speaker 1: there if we've never been there, been there present, that's
• 25:00
  Speaker 1: a great question. Well, we haven't been there personally, but
• 25:03
  Speaker 1: we have sent for example, the voyager probes, right, um.
• 25:08
  Speaker 1: And after that, we have models, right, we have models
• 25:10
  Speaker 1: that describe how galaxies are formed and how some how
• 25:14
  Speaker 1: stars work and the radiation we expect from them. And
• 25:18
  Speaker 1: so we can we can see you know, activity from
• 25:22
  Speaker 1: that gas because you know it ionizes or it or
• 25:25
  Speaker 1: it deflects light, and so we can probe it even
• 25:28
  Speaker 1: without going there, just by seeing like stuff go through it. Right, Okay, cool,
• 25:33
  Speaker 1: So we we're sort of guessing in a way. I mean,
• 25:35
  Speaker 1: we have models, but we think that's what the emptiness
• 25:39
  Speaker 1: is like up there. Yeah. Well, if there was a
• 25:41
  Speaker 1: lot more, for example, then we would see more absorption
• 25:43
  Speaker 1: of light. If there was a lot less, we would
• 25:45
  Speaker 1: see less absorption of light. Remember, gas absorbs photons, and
• 25:49
  Speaker 1: so we can have some measure of the gas and
• 25:51
  Speaker 1: the dust in our galaxy by just by seeing how
• 25:54
  Speaker 1: light is absorbed. So that's kind of the space inside
• 25:57
  Speaker 1: the galaxy between star in between solar systems that's that's
• 26:02
  Speaker 1: the interstellar medium, that's right. And remember to multiply by
• 26:05
  Speaker 1: five for a dark matter because there's a lot of
• 26:08
  Speaker 1: dark matter in the galaxy, and the galaxy is mostly
• 26:10
  Speaker 1: dark matter, and between the stars is definitely oodles and
• 26:13
  Speaker 1: oodles of dark matter on average, right on average. We
• 26:17
  Speaker 1: don't really very know very well the distribution. We know
• 26:20
  Speaker 1: again it peaks near the center of the galaxy and
• 26:22
  Speaker 1: that the amount of dark matter extends past the visible
• 26:25
  Speaker 1: edge of the galaxy, but we don't know that much
• 26:27
  Speaker 1: about exactly how it's distributed. So pretty empty, it starts
• 26:32
  Speaker 1: to drop off exactly once you get out past the
• 26:34
  Speaker 1: edge of the Solar System, but still pretty full of
• 26:36
  Speaker 1: like dark matter and and in some gas. Right, So,
• 26:45
  Speaker 1: now what happens if you keep going that, if you
• 26:47
  Speaker 1: keep going past our Solar system, past other solar systems
• 26:52
  Speaker 1: and out of the galaxy. What what do we get?
• 26:55
  Speaker 1: Well out there between the galaxies is something we very
• 26:57
  Speaker 1: cleverly call the intergalactic medium. And um, this is not
• 27:02
  Speaker 1: very exciting, and it's basically these it's it's mostly empty,
• 27:05
  Speaker 1: it's these strands of of plasma really really really dilute plasma,
• 27:10
  Speaker 1: and so it's mostly ionized hydrogen. That's what we mean
• 27:13
  Speaker 1: by plasma, and it's on average like one to ten
• 27:18
  Speaker 1: molecules of hydrogen per cubic meter. Wow. That so for
• 27:24
  Speaker 1: for a cubic meter, which is like a large moving box, right,
• 27:28
  Speaker 1: you would only see one to tend atoms of stuff. Yeah, exactly,
• 27:33
  Speaker 1: And so that's pretty empty, right. You could like take
• 27:36
  Speaker 1: a whole cubic meter and look all around and see
• 27:38
  Speaker 1: like one or two or few atoms inside the entire box.
• 27:42
  Speaker 1: That's so much more empty than a vacuum here on Earth.
• 27:46
  Speaker 1: Between galaxies, is what you're saying. Yeah, exactly, you're between galaxies.
• 27:50
  Speaker 1: And the thing that kind of blows my mind about
• 27:52
  Speaker 1: this is that, remember, the galaxies are really really really
• 27:55
  Speaker 1: far apart. So even though the density of stuff out
• 27:58
  Speaker 1: there is almost zero, if you add it all up,
• 28:03
  Speaker 1: all the stuff, all the matter between galaxies, a counter
• 28:07
  Speaker 1: about half the atoms in the entire universe. What Yeah,
• 28:12
  Speaker 1: so like half the atoms in the universe are in galaxies.
• 28:15
  Speaker 1: Half the atoms and the universe are not in galaxies.
• 28:19
  Speaker 1: And the reason that makes sense is that galaxies are
• 28:21
  Speaker 1: tiny compared to the space between galaxies. So if you
• 28:25
  Speaker 1: want to fill all the space between galaxies. With even
• 28:27
  Speaker 1: a really really low density of molecules, it takes a
• 28:31
  Speaker 1: lot of molecules to spread it out. It's like spreading
• 28:33
  Speaker 1: your frosting really thin across the cake. Wow, that's amazing
• 28:37
  Speaker 1: to think that there's more. There's as much stuff in
• 28:41
  Speaker 1: empty space quote unquote what we call empty space as
• 28:44
  Speaker 1: there are and like all those black holes and stars, stars,
• 28:49
  Speaker 1: the hamsters, hamsters, bananas, half of so much stuff is
• 28:52
  Speaker 1: just floating out in this super ultro vacuum. Yeah, exactly.
• 28:57
  Speaker 1: And between these galaxies also, we think they're must be
• 29:00
  Speaker 1: some dark matter. We don't know because it's really hard
• 29:03
  Speaker 1: to see dark matter. Remember, we only see dark matter
• 29:05
  Speaker 1: because of its gravitational effects, which means we can only
• 29:08
  Speaker 1: really see it when it's pretty dense, like the center
• 29:10
  Speaker 1: of a galaxy or a big blob. And so between
• 29:13
  Speaker 1: galaxies there might be these filaments there's a rarefied thin
• 29:17
  Speaker 1: strands of dark matter, but it's pretty hard to see that.
• 29:19
  Speaker 1: We can't see those directly. And again we know this
• 29:22
  Speaker 1: because it was if it was not that empty, then
• 29:26
  Speaker 1: we wouldn't be able to see other galaxies. So clearly
• 29:28
  Speaker 1: that's right, that's how we know, but the composition of
• 29:31
  Speaker 1: intergalactic space, because we can measure the absorption of photons
• 29:35
  Speaker 1: between here and there, and so we can sort of
• 29:37
  Speaker 1: like integrate over here to there and figure out how
• 29:40
  Speaker 1: many how much light was absorbed, how clear the spaces? Yeah, yeah,
• 29:46
  Speaker 1: And the other interesting thing that happens when you go
• 29:48
  Speaker 1: between galaxies is that you have to start to account
• 29:51
  Speaker 1: for the other crazy thing in the universe, which is
• 29:53
  Speaker 1: the dark energy. Right we said before that matters five
• 29:57
  Speaker 1: percent of the stuff in the universe. Dark of matter's
• 30:00
  Speaker 1: five times as much as this like of that, the
• 30:04
  Speaker 1: rest of it is this thing we call dark energy.
• 30:06
  Speaker 1: And the really weird thing about dark energy is that
• 30:08
  Speaker 1: it's not clustered at all. Right, Matter it gets pulled
• 30:11
  Speaker 1: together by gravity. You get planets and stars and galaxies.
• 30:14
  Speaker 1: Dark energy is spread uniformly, right, So it's equally present everywhere,
• 30:19
  Speaker 1: right even here with those right now, right right, that's
• 30:22
  Speaker 1: right between me and this microphone, between you and your seat, everywhere.
• 30:25
  Speaker 1: But because the universe is so big, spreading it uniformly
• 30:29
  Speaker 1: means it's not very dense. So, like if you added
• 30:32
  Speaker 1: up how much dark energy there is here on Earth
• 30:34
  Speaker 1: or in this room with me, there's almost none. But
• 30:36
  Speaker 1: once you start getting out there into really really far
• 30:39
  Speaker 1: stretches of space where space becomes huge, then it starts
• 30:42
  Speaker 1: to take over huge and empty, right, huge and emptier
• 30:45
  Speaker 1: and emptier. Exactly right. Yeah, I mean I think what
• 30:48
  Speaker 1: you're saying is that out there there's so little stuff
• 30:51
  Speaker 1: matter that basically dark energy is like that the main
• 30:55
  Speaker 1: thing going on out there. That's right. Once you get
• 30:58
  Speaker 1: outside our galaxy and then you get like outside the
• 31:01
  Speaker 1: cluster of galaxies that we're in, we're inside this cluster
• 31:04
  Speaker 1: of like thirty or fifty galaxies that are all sort
• 31:07
  Speaker 1: of orbiting each other, and there's these there's this plasma
• 31:09
  Speaker 1: between us, this intergalactic medium, um, this sort of infilaments
• 31:13
  Speaker 1: between the galaxies. Once you get past the cluster, then
• 31:16
  Speaker 1: you're in inter cluster space, and that's mostly dark energy.
• 31:21
  Speaker 1: I'm gonna I'm gonna take a wild guess and say that,
• 31:24
  Speaker 1: um guess that you guys call it the intercluster medium.
• 31:28
  Speaker 1: That did get that, and you got it right. And again,
• 31:31
  Speaker 1: I wish that you had been there the day that
• 31:32
  Speaker 1: that name was given, because I'm sure you would have
• 31:34
  Speaker 1: come up with a much better name. Um So, so
• 31:36
  Speaker 1: out there is mostly just dark energy, because it's really
• 31:39
  Speaker 1: sort of is kind of empty space, right, there's no
• 31:43
  Speaker 1: not very little stuff. Yeah, exactly. You can't go much
• 31:46
  Speaker 1: lower than one atom per cubic meter, right, you start
• 31:49
  Speaker 1: to get to like less than an atom per cubic meter.
• 31:52
  Speaker 1: And so that's what happens, like out there between the
• 31:54
  Speaker 1: clusters of galaxies, the number density of matter drops to
• 31:59
  Speaker 1: almost zero. So are you saying that if it drops
• 32:02
  Speaker 1: below one atom cubic meter, it means that there are
• 32:05
  Speaker 1: some cubic meters that have no atoms. There are definitely
• 32:08
  Speaker 1: cubic meters with no atoms. Yeah, if you have point
• 32:11
  Speaker 1: one atoms per cubic meter doesn't mean that every cubic
• 32:14
  Speaker 1: meter has a tenth of an atom. It means you
• 32:16
  Speaker 1: need ten cubic meters too, on average have one atoms,
• 32:21
  Speaker 1: which means it's nine of them without it. Okay, So
• 32:24
  Speaker 1: that that sounds pretty empty. Isn't that basically empty? It's
• 32:28
  Speaker 1: basically empty, But you know it's not totally empty, right,
• 32:31
  Speaker 1: and there's always dark energy in there. And the fascinating
• 32:35
  Speaker 1: thing to me is that, um, there's no box of
• 32:38
  Speaker 1: space that has no energy, right, Space itself always comes
• 32:43
  Speaker 1: with dark energy, right, like dark energy makes space and
• 32:46
  Speaker 1: space contains dark energy. We don't understand it. We don't
• 32:49
  Speaker 1: know what it is. We don't know where it comes
• 32:51
  Speaker 1: from or how it's happening, but we know it's there.
• 32:54
  Speaker 1: And what that means is that every place in space
• 32:56
  Speaker 1: has energy, and energy and mass are not that different.
• 32:59
  Speaker 1: Right equals mc squared. So what that means is that
• 33:03
  Speaker 1: anywhere there's energy, you can create mass. Like you have
• 33:06
  Speaker 1: a little density of energy, it can turn into particles
• 33:09
  Speaker 1: very briefly and then turn back into energy. Right. But
• 33:12
  Speaker 1: that that's kind of as far as we know, right,
• 33:15
  Speaker 1: because you're saying we don't really know that much about
• 33:18
  Speaker 1: dark energy. I mean, as far as you know, it
• 33:20
  Speaker 1: could maybe have little variations in it, couldn't it. It could.
• 33:25
  Speaker 1: The current thinking is that it's uniform, that it's spread
• 33:27
  Speaker 1: everywhere through space, that it's a property of space itself.
• 33:31
  Speaker 1: But you're right, we're pretty clueless, and so it could
• 33:33
  Speaker 1: be the dark energy is totally something different and that
• 33:35
  Speaker 1: we're wrong, and it has interesting structure. I suppose that
• 33:38
  Speaker 1: would be amazing, But the current thinking is that it's uniform.
• 33:42
  Speaker 1: All right, We've gone all the way from the planet
• 33:45
  Speaker 1: Earth vacuums and emptyness and planet on planet Earth all
• 33:48
  Speaker 1: the way to solar systems and galaxies and intercluster space.
• 33:52
  Speaker 1: So let's let's go even beyond that, Daniel, Let's go
• 33:55
  Speaker 1: way past that um. But first let's take another break. Okay.
• 34:11
  Speaker 1: So we we've gone from the earth emptiness of space
• 34:15
  Speaker 1: on Earth, to the Solar System, to the galaxies, to
• 34:18
  Speaker 1: inner clusters of galaxies, and we get pretty empty. You're saying,
• 34:22
  Speaker 1: you know, maybe less than one atom per cubic meter
• 34:25
  Speaker 1: out there between clusters, but you're saying that there's still
• 34:28
  Speaker 1: kind of an inherent energy and inherent stuff to space itself.
• 34:33
  Speaker 1: That's right. If you zoom out even further, remember that
• 34:35
  Speaker 1: clusters form their own kind of clusters that we call
• 34:38
  Speaker 1: cleverly superclusters, right, and that these superclusters then form these
• 34:43
  Speaker 1: big sheets, these big, these vast stretches which enclose enormous voids,
• 34:49
  Speaker 1: so they're really like frothing bubbles right where the edges
• 34:52
  Speaker 1: of the bubbles are all these superclusters of clusters of
• 34:55
  Speaker 1: galaxies of stars. And to what's inside those voids, well,
• 34:59
  Speaker 1: this essentially no matter. I mean, we don't know. We can't,
• 35:02
  Speaker 1: like we haven't measured it the way we've measured these
• 35:04
  Speaker 1: other things, so we know it's a very very very
• 35:07
  Speaker 1: small amount of matter, like a number of protons is tiny.
• 35:11
  Speaker 1: But you know there's dark energy there, and there's energy
• 35:15
  Speaker 1: in space itself. You know, for example, the Higgs boson
• 35:18
  Speaker 1: the Higgs field is something which even if there's no
• 35:22
  Speaker 1: particles there, it still has energy. Something we call the
• 35:25
  Speaker 1: vacuum expectation value is non zero, like the ground state
• 35:29
  Speaker 1: of the Higgs field is not at zero, which means
• 35:33
  Speaker 1: this energy in every space and energy can get turned
• 35:35
  Speaker 1: into mass. There's this fun thing about quantum mechanics where
• 35:38
  Speaker 1: you can create virtual particles. You have energy, you can
• 35:41
  Speaker 1: briefly create mass out of it and then back into energy,
• 35:45
  Speaker 1: and so that's probably happening everywhere in the universe. You
• 35:48
  Speaker 1: take a random box of space inside one of these
• 35:51
  Speaker 1: super voids inside the bubble, and briefly particles will be
• 35:54
  Speaker 1: being created and then destroyed. But that's a quantum physics thing, right,
• 35:58
  Speaker 1: isn't it. Yeah, exactly, that's kantom mechanical. There's this uncertainty
• 36:02
  Speaker 1: and this randomness, and some particles are always fluctuating in
• 36:06
  Speaker 1: and out of the vacuum. So you're saying, theoretically you
• 36:09
  Speaker 1: might be able to have truly empty space, but it's
• 36:12
  Speaker 1: sort of not empty all the time forever. Yeah, say
• 36:15
  Speaker 1: you like did the painstaking job or removing every single
• 36:18
  Speaker 1: particle you found from a cubic meter, then you go
• 36:21
  Speaker 1: back to be like, wait a second, I just found
• 36:22
  Speaker 1: another particle. What it disappeared? Oh wait, there's another one
• 36:25
  Speaker 1: over here. It's sort of like playing quantum Waca mole
• 36:28
  Speaker 1: because you can never get all the energy out of
• 36:30
  Speaker 1: that box and say you can effectively not ensure that
• 36:33
  Speaker 1: there's no matter, right, you can't ensure there's zero matter
• 36:36
  Speaker 1: in there because you can't get all the energy out,
• 36:38
  Speaker 1: and energy you can always fluctuate back into matter. And
• 36:42
  Speaker 1: that's a property you're saying, a property of space itself,
• 36:45
  Speaker 1: Like space by itself has energy to it meat we
• 36:49
  Speaker 1: need has the propensity to make matter always. Yeah, and
• 36:53
  Speaker 1: remember that space is a thing, right, It's not like emptiness. Right,
• 36:56
  Speaker 1: Space itself is a thing. It can ripple, it can expand, end,
• 37:00
  Speaker 1: it can um, it can bend, and so there's some
• 37:04
  Speaker 1: has properties, right, And it's not nothingness. I'm not saying
• 37:08
  Speaker 1: nothing has energy. I'm saying space has energy. And we're
• 37:11
  Speaker 1: only just now beginning to grapple with what space itself is.
• 37:15
  Speaker 1: So if you think space having energy sounds weird, then
• 37:19
  Speaker 1: remember that space is a thing. It's like, you know,
• 37:21
  Speaker 1: fish scientists swimming through water and discovering that water is
• 37:24
  Speaker 1: a thing. Space is definitely a thing that has some energy. Now,
• 37:27
  Speaker 1: another deeper question is are there places without space? Right?
• 37:32
  Speaker 1: Is there past the edge of the universe? If the
• 37:34
  Speaker 1: universe's finite, are there places where there is no space,
• 37:38
  Speaker 1: no energy, and therefore no energy. That might be possible,
• 37:41
  Speaker 1: but that wouldn't be empty space. That would be emptyness
• 37:45
  Speaker 1: or nothingness or something. But that's pretty hard to grapple with,
• 37:49
  Speaker 1: you know. Conceptually, you're saying, it's sort of like if
• 37:52
  Speaker 1: fish scientists would be like asking having a podcast, a
• 37:56
  Speaker 1: couple of fish talking to the podcast, asking themselves it
• 38:00
  Speaker 1: and water be empty, and basically the answer is ridiculous
• 38:04
  Speaker 1: because we know water is stuff. That's right, And then
• 38:06
  Speaker 1: they're having trouble thinking about like is there an edge
• 38:09
  Speaker 1: to the pond? Like what's above the surface of the pond? Man,
• 38:14
  Speaker 1: what does it mean to not have water? I think
• 38:15
  Speaker 1: they would be sort of what they mean by antwer
• 38:17
  Speaker 1: would be sort of like, can can you have water?
• 38:19
  Speaker 1: Pure water? Right? Like water with noth no, no containmants
• 38:25
  Speaker 1: and it just pure h two oh. That that would
• 38:27
  Speaker 1: be the question for them that we are sort of asking,
• 38:29
  Speaker 1: can if space can be empty? Yeah? Exactly, And then
• 38:32
  Speaker 1: the deeper question for them would be can you have
• 38:35
  Speaker 1: places without water? And so we would ask can you
• 38:39
  Speaker 1: have places without space? Does that even mean anything? And
• 38:42
  Speaker 1: that's pretty hard to think about. So I think the
• 38:45
  Speaker 1: answer is we're pretty sure you can't have totally empty
• 38:48
  Speaker 1: space because of quantum mechanics and dark energy and the
• 38:50
  Speaker 1: Higgs Boson vacuum expectation value um, but you might be
• 38:56
  Speaker 1: able to have places without space or you know, past
• 38:59
  Speaker 1: the edge of the unit verse where her where the
• 39:01
  Speaker 1: space ends. But we don't know. That's that part is
• 39:05
  Speaker 1: really speculative. And maybe there is a part of the
• 39:07
  Speaker 1: universe that is all water with fish scientists asking that
• 39:10
  Speaker 1: question where all the podcasts are all wet, and I
• 39:14
  Speaker 1: think that their their podcasts are called podcasts. And so
• 39:25
  Speaker 1: to recap near the Earth, we have like a few
• 39:28
  Speaker 1: million molecules per cubic meter, and then once you get
• 39:31
  Speaker 1: outside the Solar system, it drops to like between a
• 39:34
  Speaker 1: million and a hundred molecules per cubic meter. Then between
• 39:38
  Speaker 1: galaxies it gets down to like one to ten per
• 39:40
  Speaker 1: cubic meter. But the emptiest place in space is out
• 39:44
  Speaker 1: there in the voids between the bubbles of superclusters, which
• 39:48
  Speaker 1: is crazy empty. Well, I guess the question that the
• 39:51
  Speaker 1: answer to the question can space be empty? Is yes,
• 39:54
  Speaker 1: sort of, but not all the time, or not an
• 39:57
  Speaker 1: average or not for long kind of I would say.
• 40:01
  Speaker 1: I would say most of the space we see is
• 40:03
  Speaker 1: not empty, and as you get further out, it gets
• 40:05
  Speaker 1: emptier and emptier and emptier to get pretty empty, but
• 40:08
  Speaker 1: never totally truly empty, but but not not all the time, right, Like, um,
• 40:14
  Speaker 1: you could my mic get a cubing meter with nothing,
• 40:16
  Speaker 1: absolutely nothing in it, no matter, but before long you'll
• 40:21
  Speaker 1: see matter popping in and out all the time. Yeah,
• 40:24
  Speaker 1: before long, meaning like ten of the twenty three seconds.
• 40:26
  Speaker 1: So congratulations in your accomplishments. That's that's what my grandma
• 40:33
  Speaker 1: would call it. A Panamanian minute. Okay, I don't know
• 40:37
  Speaker 1: what that means, but it sounds awesome, all right. I
• 40:39
  Speaker 1: hope that podcast filled your space with interesting knowledge and
• 40:43
  Speaker 1: ideas to think about. That's right, I hope we blew
• 40:45
  Speaker 1: your mind and injected some space in there. And remember
• 40:48
  Speaker 1: that we live in a vast universe filled mostly with nothing, yeah,
• 40:53
  Speaker 1: except on the in the space around you, So take
• 40:56
  Speaker 1: some time to appreciate all this stuff around you because
• 40:59
  Speaker 1: it could be pretty empty out there, all right. Thanks
• 41:02
  Speaker 1: everyone for listening, and if you have questions, send them
• 41:04
  Speaker 1: to feedback at Daniel and Jorge dot com. Thanks for listening,
• 41:08
  Speaker 1: see you next time. If you still have a question
• 41:18
  Speaker 1: after listening to all these explanations, please drop us a line.
• 41:21
  Speaker 1: We'd love to hear from you. You can find us
• 41:24
  Speaker 1: at Facebook, Twitter, and Instagram at Daniel and Jorge That's
• 41:27
  Speaker 1: one word, or email us at feedback at Daniel and
• 41:31
  Speaker 1: Jorge dot com. Thanks for listening and remember that Daniel
• 41:34
  Speaker 1: and Jorge Explain the Universe is a production of I
• 41:37
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• 41:41
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• 41:44
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