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Was the Big Bang left handed? · Daniel and Kelly’s Extraordinary Universe

• 0:05
  Speaker 1: Unraveling the nature of the universe is a bit like
• 0:08
  Speaker 1: solving a murder mystery. You have to look very carefully
• 0:10
  Speaker 1: at all the clues. You have to pull really hard
• 0:13
  Speaker 1: on any thread that looks weird it's unexplained, because any
• 0:16
  Speaker 1: of them might be the key that solves the whole mystery.
• 0:20
  Speaker 1: Throughout history, whenever we've seen something we didn't understand, it's
• 0:24
  Speaker 1: often turned out to be a big screaming clue about
• 0:28
  Speaker 1: the next deeper layer of understanding reality. When we saw
• 0:31
  Speaker 1: patterns in the periodic table, they were obvious but unexplained
• 0:35
  Speaker 1: for many years until we were able to dig deeper
• 0:37
  Speaker 1: and discover that they all came out of how electrons
• 0:41
  Speaker 1: arranged themselves in shells around the nucleus. The similarity of
• 0:44
  Speaker 1: the shape of the coastlines of Africa and South America
• 0:47
  Speaker 1: a big clue that over millions of years, the continents
• 0:50
  Speaker 1: themselves were in motion, and these two had once been joined.
• 0:54
  Speaker 1: So amazing realizations can come from refusing to ignore little
• 0:59
  Speaker 1: time clues that bother you at night. So every time
• 1:03
  Speaker 1: we see something that doesn't make sense, we should dig
• 1:06
  Speaker 1: deeper and look for a reason. And that's especially true
• 1:09
  Speaker 1: when there's something that we don't understand about the whole
• 1:12
  Speaker 1: universe when we think it should has balance, but instead
• 1:16
  Speaker 1: it's out of balance. Why is there more matter than antimatter?
• 1:20
  Speaker 1: Why are some forces weaker than others? Particle physics is
• 1:23
  Speaker 1: filled with these kinds of mysteries, and today on the podcast,
• 1:27
  Speaker 1: we'll be digging deep into one unexplained choice. The universe
• 1:31
  Speaker 1: seems to have made billions of years ago between being
• 1:35
  Speaker 1: righty or lefty. Life is left handed. Particles prefer to
• 1:39
  Speaker 1: be left handed, though most humans are right handed. Today,
• 1:42
  Speaker 1: on the podcast, we'll be asking was the Big Bang
• 1:46
  Speaker 1: also left handed? Welcome to Daniel and Kelly's Extraordinary left
• 1:52
  Speaker 1: Handed Universe.
• 2:06
  Speaker 2: Hello. I'm Kelly Wienersmith. I study parasites, and my family
• 2:10
  Speaker 2: is fifty percent left handed and fifty percent right handed.
• 2:15
  Speaker 3: Hi.
• 2:15
  Speaker 1: I'm Daniel. I'm a particle physicist, and I'd give my
• 2:18
  Speaker 1: right hand to be ambidextros.
• 2:20
  Speaker 2: Well, Okay, that doesn't really make sense the more I
• 2:21
  Speaker 2: think about it, but I would love to be ambidextris too.
• 2:24
  Speaker 2: How does it fall out in your family?
• 2:26
  Speaker 1: We have one lefty, a bunch of righty's, and my
• 2:30
  Speaker 1: mom was ambidextris. She could write with both hands, and
• 2:33
  Speaker 1: some things she'd liked to do with her left hand,
• 2:34
  Speaker 1: like cutting with scissors, and other things she liked to
• 2:36
  Speaker 1: do with her right hand, like stirring a bowl of soup.
• 2:39
  Speaker 2: Interesting, I don't do anything with either hand well, like
• 2:42
  Speaker 2: pipe petting didn't go well. My writing's illegible from either hand,
• 2:46
  Speaker 2: but you know I can type, okay?
• 2:48
  Speaker 1: And who in your family is left handed?
• 2:50
  Speaker 2: Zach? And we think ben so.
• 2:51
  Speaker 1: Zach's a member of the Secret Society of Left Handers.
• 2:54
  Speaker 2: And the Secret Society of Red headed People. Yes, he's
• 2:58
  Speaker 2: involved in lots of secret societies, maybe in charge of everything.
• 3:03
  Speaker 1: I wouldn't mind having cartoonists be in charge of most stuff.
• 3:05
  Speaker 1: I think that would be a great way to run
• 3:07
  Speaker 1: the world. What's the name for that, you have democracy, oligarchy, cartoonocracy?
• 3:12
  Speaker 2: Yeah, I don't know, but I can tell you that
• 3:15
  Speaker 2: he doesn't run the household because he might not be
• 3:19
  Speaker 2: confident to do that. And so I don't know that
• 3:22
  Speaker 2: we should give him too much more power. And I
• 3:24
  Speaker 2: don't think he wants more power. So I think maybe
• 3:27
  Speaker 2: rule by the cartoonists, this one in particular, is maybe
• 3:30
  Speaker 2: not a great idea. What would it be like if
• 3:32
  Speaker 2: the world were ruled by physicists, we.
• 3:35
  Speaker 1: Would spend a lot more money on particle colliders. Oh
• 3:38
  Speaker 1: my gosh, Yes, we would know so much more about
• 3:40
  Speaker 1: the universe, but.
• 3:41
  Speaker 2: We'd spend less money on soap.
• 3:46
  Speaker 1: Sorry, fair, fair, Nobody in office would be wearing a suit,
• 3:54
  Speaker 1: that's for sure.
• 3:55
  Speaker 2: That's for sure. That's a world I can get behind.
• 3:59
  Speaker 1: Well, we seek to find balance between the physicists and
• 4:02
  Speaker 1: the cartoonists, and the left handiers and the right handers
• 4:05
  Speaker 1: and everything in the universe, which is why on today's
• 4:07
  Speaker 1: podcast we're gonna be talking about symmetry and balance and
• 4:11
  Speaker 1: imbalance in the universe.
• 4:13
  Speaker 2: So I'm super interested in this topic because I only
• 4:15
  Speaker 2: had a chance to sort of like realize that it
• 4:18
  Speaker 2: existed back when we were writing Souonish, because we wrote
• 4:21
  Speaker 2: a little note of bene on George Church, who is
• 4:24
  Speaker 2: trying to make organisms where every one of their molecules
• 4:27
  Speaker 2: is the opposite handedness as it is now. And the
• 4:32
  Speaker 2: ultimate goal, as I understood it, was that if you
• 4:35
  Speaker 2: had a human of opposite handedness, no pathogens or parasites
• 4:39
  Speaker 2: could recognize our receptors and they would never be able
• 4:43
  Speaker 2: to infect us, and so you would be free from
• 4:45
  Speaker 2: all infection.
• 4:46
  Speaker 1: But you also wouldn't have a microbiome, so you couldn't
• 4:48
  Speaker 1: digest any food, right.
• 4:49
  Speaker 2: So your microbiome would also have to be made opposite handed,
• 4:53
  Speaker 2: and then all of your foods would have to be
• 4:55
  Speaker 2: made opposite handed, and that just seems like way too
• 4:58
  Speaker 2: much work for the trade off and all. So like,
• 5:00
  Speaker 2: if a global supply chain problem popped up, could you
• 5:03
  Speaker 2: never feed anyone because they need the opposite handedness bread?
• 5:06
  Speaker 2: It was complicated, But I remember when I was doing
• 5:08
  Speaker 2: the research thinking why is there such a trend in
• 5:11
  Speaker 2: handedness for molecules? Like what caused that? And then I
• 5:14
  Speaker 2: got too busy and so I never dug in, And
• 5:16
  Speaker 2: today we get to find out about that.
• 5:18
  Speaker 1: That's right, So it'll be super fascinating when there's an
• 5:20
  Speaker 1: asymmetry in the universe, when the universe seems to have
• 5:23
  Speaker 1: made one choice, because then you got to ask, like,
• 5:25
  Speaker 1: why not the other choice? What does it mean? Is
• 5:27
  Speaker 1: it random? Is there a reason? Could it have been
• 5:29
  Speaker 1: the other way? Are there other universes out there where
• 5:32
  Speaker 1: another choice was made? And does that explain my whole childhood? Basically?
• 5:38
  Speaker 2: Wow, whoa it got deep?
• 5:41
  Speaker 1: And so this stretches from the mathematics of handedness, to
• 5:44
  Speaker 1: the handedness of life, to the handedness of particles, and
• 5:47
  Speaker 1: even the handedness of the whole universe and the origin
• 5:52
  Speaker 1: of the universe itself. So I went out there and
• 5:55
  Speaker 1: I asked folks what they knew about this topic, if
• 5:58
  Speaker 1: they thought the Big Bang could have been left handed,
• 6:02
  Speaker 1: If you'd like to play for future episodes of the podcast,
• 6:04
  Speaker 1: please don't be shy right to us two questions at
• 6:07
  Speaker 1: Danielandkelly dot org. So think about it for a moment.
• 6:11
  Speaker 1: Do you think the Big Bang could have been left handed?
• 6:15
  Speaker 1: Here's what people had to say.
• 6:17
  Speaker 4: Okay, this has to do with chirality, But I don't
• 6:19
  Speaker 4: think kyality is at the fundamental particle level that it
• 6:24
  Speaker 4: wouldn't be manifested there, you know, because you've got flavor, spin, charge,
• 6:28
  Speaker 4: flavor color, but you definitely don't have chirality built into
• 6:32
  Speaker 4: the core properties. Now, it does come up in chemistry.
• 6:35
  Speaker 4: I know that all chemistry on Earth is a certain
• 6:37
  Speaker 4: kiral and I can't remember if it's left right, but
• 6:39
  Speaker 4: it's one type. And if we get a meteor that
• 6:42
  Speaker 4: comes that has a different type, that shows some type
• 6:44
  Speaker 4: of organic biological life, then we would know that it's
• 6:48
  Speaker 4: that it's alien and not something you know that came
• 6:51
  Speaker 4: from Earth.
• 6:52
  Speaker 5: Let's see, in molecules, you can have handedness based on
• 6:56
  Speaker 5: the arrangement of the atoms in the same way your
• 6:58
  Speaker 5: hands are left handed and right handed based on the
• 7:00
  Speaker 5: arrangement of fingers. But in a soup of particles like protons,
• 7:04
  Speaker 5: surely there's no way their arrangement can be left handed
• 7:08
  Speaker 5: or right handed.
• 7:09
  Speaker 3: Considering the Big Bang was everywhere all at once, and
• 7:13
  Speaker 3: we ended up in a universe with both right and
• 7:16
  Speaker 3: left handed fundamental force particles, then maybe it was both.
• 7:22
  Speaker 2: So I feel like the intuition here from the answers
• 7:25
  Speaker 2: tends to be that folks think the Big Bang was
• 7:28
  Speaker 2: probably not left handed and produced an equal amount approximately
• 7:31
  Speaker 2: of left and right handed molecules. That totally matches my
• 7:34
  Speaker 2: intuition as well, but is not actually the answer, right.
• 7:39
  Speaker 1: Yeah, it reveals something about our prejudice, what we think
• 7:42
  Speaker 1: is natural, what makes sense, And I think it's super
• 7:44
  Speaker 1: fascinating in science what answers people will accept without further
• 7:48
  Speaker 1: explanation because it aligns with their intuition and they're like, oh, yeah,
• 7:51
  Speaker 1: that makes sense, And what answers require more explanation, and
• 7:55
  Speaker 1: for a lot of people hearing oh it was symmetric,
• 7:57
  Speaker 1: it was a balance between left and right handed, and
• 7:59
  Speaker 1: then like, yeah, cool, of course it was. That doesn't
• 8:02
  Speaker 1: require any more explanation. But if you tell them no,
• 8:04
  Speaker 1: it's left handed, or no it was right handed, then
• 8:06
  Speaker 1: to ask why. And I think all the possible outcomes
• 8:09
  Speaker 1: need a why. You know, why should it be symmetric?
• 8:12
  Speaker 1: But we have this innate preference for symmetry for balance
• 8:15
  Speaker 1: in the universe, which I think says something about us,
• 8:18
  Speaker 1: but I'm not sure exactly what it says.
• 8:20
  Speaker 2: I think I would like to have you on the
• 8:22
  Speaker 2: next panel that judges my grants. I like the way
• 8:25
  Speaker 2: you think about this stuff.
• 8:26
  Speaker 1: It all needs answers, It all needs answers exactly every
• 8:29
  Speaker 1: question is worth asking.
• 8:31
  Speaker 2: But yeah, it does make me wonder what questions we
• 8:34
  Speaker 2: should be asking that would like have amazing impacts on
• 8:37
  Speaker 2: how we view the world, but we just don't think
• 8:39
  Speaker 2: to ask them because our gut says they make sense.
• 8:42
  Speaker 1: Exactly to me. This tendency suggests that there probably are
• 8:46
  Speaker 1: questions we should be digging into more deeply, or it's
• 8:49
  Speaker 1: just accepting the answers because they seem right to us
• 8:51
  Speaker 1: without really understanding what's going on, and maybe in one
• 8:55
  Speaker 1: hundred years or maybe when the aliens come, they're going
• 8:57
  Speaker 1: to be like, why didn't you think about that more deeply?
• 9:00
  Speaker 1: We would be like, I don't know, it just made sense.
• 9:03
  Speaker 2: Set right, right, man, exactly? Yeah?
• 9:07
  Speaker 5: All right.
• 9:07
  Speaker 2: Well, I think for anyone who hasn't thought of this
• 9:09
  Speaker 2: concept yet, or anyone who was lucky enough to not
• 9:12
  Speaker 2: have to go through chemistry, is maybe a little confused
• 9:15
  Speaker 2: about what we mean by this handedness thing. So let's
• 9:17
  Speaker 2: start at the beginning. What does it mean for something
• 9:20
  Speaker 2: to have a handedness?
• 9:21
  Speaker 1: Yeah, left or right handedness really is a mathematical thing.
• 9:25
  Speaker 1: It's a geometric thing and super fascinating. So let's start
• 9:28
  Speaker 1: in two dimensional space. Imagine that you take two arrows right,
• 9:32
  Speaker 1: so you know they have a tip and a tail,
• 9:35
  Speaker 1: and then stick their tails together and have their tips
• 9:38
  Speaker 1: be ninety degrees apart. So now you have like two
• 9:41
  Speaker 1: arrows that are pointing perpendicular to each other. Right now,
• 9:46
  Speaker 1: in two dimensional space, just like on a sheet, any
• 9:49
  Speaker 1: pair of arrows you make are always going to be
• 9:51
  Speaker 1: essentially equivalent, And by equivalent, I mean that you could
• 9:54
  Speaker 1: line them up on top of each other, like move
• 9:56
  Speaker 1: them and spin them and put them on top of
• 9:58
  Speaker 1: each other. They're always going to line up perfectly. There's
• 10:01
  Speaker 1: no way to make a pair of arrows to follow
• 10:04
  Speaker 1: those rules where they're perpendicular to each other, where you
• 10:06
  Speaker 1: can't then line them up. So that's two dimensional space, right,
• 10:10
  Speaker 1: there's no handedness. But if you label one of the
• 10:12
  Speaker 1: arrows X and the other one y, so they're no
• 10:15
  Speaker 1: longer two totally symmetrical identical vectors, but they have these
• 10:19
  Speaker 1: labels on them. Now there are two ways to arrange
• 10:22
  Speaker 1: these two arrows, Like if the X arrow is straight
• 10:26
  Speaker 1: up in front of you, then the Y arrow can
• 10:29
  Speaker 1: be to its left or to its right. And because
• 10:32
  Speaker 1: you have these labels, there's now no way to spin
• 10:35
  Speaker 1: the left version of it to make it look like
• 10:38
  Speaker 1: the right version. To do that, to have one lay
• 10:41
  Speaker 1: on top of each other, so the x is align
• 10:42
  Speaker 1: and the ys align, you'd have to flip it over
• 10:46
  Speaker 1: essentially reflect it, make a mirror image, go from left
• 10:49
  Speaker 1: to right. It's analogous to notions of clockwise and counterclockwise
• 10:53
  Speaker 1: on the surface of a clock. Also two dimensional. Now
• 10:56
  Speaker 1: expand our universe, add a third dimension above and below
• 10:59
  Speaker 1: the plane and add another arrow. Take your two arrows
• 11:03
  Speaker 1: that are perpendicular to each other. You could think of
• 11:05
  Speaker 1: them as like the X axis and the y axis,
• 11:07
  Speaker 1: or you could think of them as like your thumb
• 11:09
  Speaker 1: and your pointy finger right, that are perpendicularly to each other.
• 11:12
  Speaker 1: And now add a third arrow that comes out from
• 11:15
  Speaker 1: where the first two were joined. Now you have to
• 11:17
  Speaker 1: make a choice. Do you go up above the plane
• 11:20
  Speaker 1: or down below the plane? And you might think, oh,
• 11:23
  Speaker 1: it doesn't matter if I stick it above the plane,
• 11:26
  Speaker 1: I can just rotate it to make it below the plane, right,
• 11:28
  Speaker 1: But it actually does matter. If you choose the arrow
• 11:31
  Speaker 1: that goes up above the plane, and then you rotate
• 11:33
  Speaker 1: the whole thing so the arrow goes below the plane,
• 11:36
  Speaker 1: you'll find that the other two don't line up to
• 11:38
  Speaker 1: the first two. There's no way to take that set
• 11:40
  Speaker 1: where the arrow is above the plane and rotate it
• 11:43
  Speaker 1: to match the arrow those below the plane. You can
• 11:45
  Speaker 1: see this very easily with your hands. Your hands on
• 11:48
  Speaker 1: his left handed when it's right handed. That's why we
• 11:50
  Speaker 1: call them that. If you take your thumb and your
• 11:54
  Speaker 1: pointy finger and you make them ninety degrees apart, then
• 11:57
  Speaker 1: you have your middle finger stick perpendicular to your pal
• 12:00
  Speaker 1: so it's perpendicular to the other two. Then you have
• 12:02
  Speaker 1: like an X, Y, Z axis, but there's no way
• 12:05
  Speaker 1: to orient them, so they line up on top of
• 12:06
  Speaker 1: each other. Is one is left handed and one is
• 12:08
  Speaker 1: right handed?
• 12:09
  Speaker 2: All right, So I get that. But when I think
• 12:11
  Speaker 2: of handedness, I feel like I'm thinking of my hands
• 12:14
  Speaker 2: and the X and the Y direction and not the
• 12:15
  Speaker 2: Z direction. Yeah, it still doesn't work in those two dimensions.
• 12:20
  Speaker 2: Is the point that, Kelly, your hands are actually three dimensional.
• 12:23
  Speaker 2: You're an idiot. Stop thinking about this like they're two dimensional.
• 12:26
  Speaker 1: No, you're not an idiot. Your hands are three dimensional.
• 12:28
  Speaker 1: You're exactly right. And the reason that you're like, make
• 12:31
  Speaker 1: your hands flat, you're thinking, I make my hands flat,
• 12:34
  Speaker 1: I lay them on top of each other. They're still
• 12:36
  Speaker 1: not the same, right, even in sort of flat hand
• 12:39
  Speaker 1: two dimensional world. The thing is that you're right. They're
• 12:41
  Speaker 1: not two dimensional, and if they were, you could make
• 12:44
  Speaker 1: them line on top of each other and be exactly
• 12:46
  Speaker 1: the same. The reason that they can't is because they
• 12:49
  Speaker 1: have a top and a bottom, right, they have a thickness.
• 12:51
  Speaker 1: If you try to put your hands together, then you
• 12:54
  Speaker 1: meet your palms together. Then they're inverted in that third dimension,
• 12:57
  Speaker 1: so you still are working in a three dimensional world.
• 12:59
  Speaker 1: If you squeezed your hands in a hydraulic press so
• 13:02
  Speaker 1: they were infinitely flat, then you could make them identical
• 13:05
  Speaker 1: and lay them on top of each other.
• 13:06
  Speaker 2: I don't think it's worth it for this purpose.
• 13:09
  Speaker 1: That's why we have thought experiments. You don't have to
• 13:11
  Speaker 1: actually do it. You could just think of it that way.
• 13:13
  Speaker 1: So that's what handedness is, and that's where it comes from.
• 13:16
  Speaker 1: It comes from our hands. Right, one hand is left handed,
• 13:18
  Speaker 1: one hand is right handed. Amazingly, these words actually make
• 13:21
  Speaker 1: sense and the technical definition lines up with your knowledge.
• 13:25
  Speaker 2: Another example of how humans sort of take the way
• 13:28
  Speaker 2: that we see and experience the world and overlay it
• 13:30
  Speaker 2: on our science.
• 13:31
  Speaker 1: Yeah, exactly right. And what would aliens call this kind.
• 13:34
  Speaker 2: Of stuff tentaicleness.
• 13:38
  Speaker 1: It's fascinating because this is a basic property of geometry, right,
• 13:42
  Speaker 1: and it's totally arbitrary. There's nothing special but left handed
• 13:45
  Speaker 1: or right handed right. It's just how do you orient
• 13:48
  Speaker 1: these three vectors? And it would be really weird if
• 13:51
  Speaker 1: the universe for some reason preferred one or the other. Mathematically,
• 13:55
  Speaker 1: they're totally equivalent, they're completely symmetrical. There's no reason for
• 13:59
  Speaker 1: one to be more fundamental or more basic. There's just
• 14:03
  Speaker 1: two choices to make here, and not everything in the
• 14:06
  Speaker 1: universe has a handedness, right, we're talking about this combination
• 14:10
  Speaker 1: of three vectors, or your three fingers have a handedness.
• 14:13
  Speaker 1: But take a sphere, for example. A sphere has no handedness.
• 14:16
  Speaker 1: There's no choices to make. There a way you can
• 14:18
  Speaker 1: tell something as handedness is put it in front of
• 14:20
  Speaker 1: a mirror. A mirror flips the handedness. Like if you
• 14:24
  Speaker 1: put your left hand in front of a mirror, it
• 14:26
  Speaker 1: looks like a right hand. If you put your right
• 14:28
  Speaker 1: hand in front of a mirror, it looks like a
• 14:30
  Speaker 1: left hand. Put a sphere in front of a mirror,
• 14:32
  Speaker 1: what do you get a sphere? Right, There's no handedness
• 14:36
  Speaker 1: to a sphere. So some things have handedness and some
• 14:40
  Speaker 1: things don't have handedness. So that's the sort of mathematics
• 14:43
  Speaker 1: of handedness. And you might imagine a perfect universe everything
• 14:46
  Speaker 1: would be symmetric. There's no reason to choose one or
• 14:48
  Speaker 1: the other. But as we already talked about in this episode,
• 14:51
  Speaker 1: nobody is really symmetric. Like I use my right hand right,
• 14:55
  Speaker 1: I am right handed, it's a part of me that
• 14:58
  Speaker 1: breaks this symmetry that for so reason prefers to use
• 15:01
  Speaker 1: my right hand to need doe and to write doodles
• 15:04
  Speaker 1: and to point at things and all sorts of stuff.
• 15:06
  Speaker 1: And some people are left handed. So the symmetry is
• 15:09
  Speaker 1: broken sort of two levels, right. One level is every
• 15:12
  Speaker 1: individual person prefers one or the other, and the population
• 15:17
  Speaker 1: has way more righties than lefties. So this symmetry is
• 15:20
  Speaker 1: already broken even from the place where you've defined it.
• 15:23
  Speaker 2: Fun fact, this happens in the animal kingdom too. I
• 15:26
  Speaker 2: remember a talk, Oh my gosh, this was two decades ago,
• 15:28
  Speaker 2: but they were looking at blind kfish and they put
• 15:31
  Speaker 2: them in an environment with legos in the middle, and
• 15:33
  Speaker 2: it was a circular tank, and the fish to explore
• 15:37
  Speaker 2: the environment, they like get you know, the vibrations or
• 15:39
  Speaker 2: the water currents, they feel them on one side of
• 15:41
  Speaker 2: their body to figure out where things are. And so
• 15:43
  Speaker 2: they'd swim around, and you could tell that they had
• 15:46
  Speaker 2: figured out like what their environment was like because they
• 15:48
  Speaker 2: eventually slowed down and like stopped swimming. But as soon
• 15:51
  Speaker 2: as you moved the legos in a different configuration, they'd
• 15:54
  Speaker 2: start swimming around again. A lot, they could tell the
• 15:57
  Speaker 2: environment had changed and they wanted to understand how it
• 15:59
  Speaker 2: had changed. And they specifically would swim with one side
• 16:02
  Speaker 2: of their body facing the legos because they had a
• 16:06
  Speaker 2: body side that they preferred to collect information on, and
• 16:10
  Speaker 2: so like even fish exhibits something like a preference for
• 16:13
  Speaker 2: one side over the other. Anyway, I always remembered that
• 16:16
  Speaker 2: it was like amazing that blind cavefish were responding to
• 16:19
  Speaker 2: changes in their environments. Animals are incredible.
• 16:21
  Speaker 1: We've noticed that our dog seems to have a preference,
• 16:24
  Speaker 1: Like when we ride in the car, he will stick
• 16:26
  Speaker 1: his head fully out the window, but only on the
• 16:28
  Speaker 1: right side. On the left side, he will stick his
• 16:30
  Speaker 1: nose out the window, but he won't like all the
• 16:32
  Speaker 1: way climb up on the armrest and get his whole
• 16:34
  Speaker 1: shoulders out the window. So he seems to prefer the
• 16:37
  Speaker 1: wind on the right side of the car. And that
• 16:39
  Speaker 1: makes me wonder, like, is he more comfortable with his
• 16:42
  Speaker 1: right paw and looking out that window requires more strength
• 16:45
  Speaker 1: from that leg or something, or is he fundamentally a
• 16:48
  Speaker 1: righty I mean, have we done a lot of experiments
• 16:50
  Speaker 1: on animals to determine, you know, if they're right left handed? Like,
• 16:53
  Speaker 1: do chimpanzees use their right or left hand?
• 16:56
  Speaker 4: More?
• 16:57
  Speaker 1: Do you know?
• 16:57
  Speaker 2: I don't know. I think we need to get Katie
• 16:59
  Speaker 2: Golded on the show from Creature Feature and she'll let
• 17:01
  Speaker 2: us know. But I do not know the answer to that.
• 17:03
  Speaker 2: So the left side is the side that the other
• 17:05
  Speaker 2: cars are coming from. I wonder if it just feels
• 17:08
  Speaker 2: safer to stick your head out farther on the opposite
• 17:10
  Speaker 2: side than like towards incoming traffic.
• 17:13
  Speaker 1: Oh, we'll have to do some experiments with folks in
• 17:15
  Speaker 1: England to see if their dogs prefer the opposite side.
• 17:19
  Speaker 2: There you go, that's a good experiment.
• 17:21
  Speaker 1: We're doing the natural experiment right here on Earth, folks.
• 17:25
  Speaker 1: So you see that pop up in your daily life
• 17:27
  Speaker 1: and in your own experience and in your family. But
• 17:30
  Speaker 1: it turns out to also be important in the biochemistry
• 17:33
  Speaker 1: of life and later on more fundamentally, in physics itself.
• 17:37
  Speaker 2: Yes, we said chemistry, but stick with us. This is exciting,
• 17:58
  Speaker 2: all right, So we're back. We've talked about handedness, and
• 18:01
  Speaker 2: I remember from organic chemistry and biokam that organic molecules
• 18:06
  Speaker 2: are left handed in right handed And actually, when we
• 18:08
  Speaker 2: were researching studish, Zach discovered that spearment and care away,
• 18:13
  Speaker 2: which are very different tastes, are molecules with opposite handedness.
• 18:18
  Speaker 2: Whoa and so like those, opposite handedness results in completely
• 18:22
  Speaker 2: different ways that it interacts with our body. So anyway,
• 18:24
  Speaker 2: molecules have handedness and our chirrol and why.
• 18:30
  Speaker 1: Yeah, So we don't fundamentally know the answer, and you
• 18:33
  Speaker 1: might be wondering, like, what does handedness mean for a molecule, Well,
• 18:37
  Speaker 1: it just means that if you put it in front
• 18:39
  Speaker 1: of a mirror, you don't get the same molecules. So
• 18:42
  Speaker 1: a molecule is more like the three first fingers on
• 18:45
  Speaker 1: your hand or the xyz axis than it is like
• 18:48
  Speaker 1: a sphere. Right, They're not symmetric. They have a handedness
• 18:51
  Speaker 1: to them, so you can't just like spin a left
• 18:54
  Speaker 1: handed version of amino acids into a right handed version
• 18:57
  Speaker 1: of methane. It's like fundamentally a diff molecule. You can
• 19:01
  Speaker 1: tell which one is left and which one is right.
• 19:03
  Speaker 1: And as Kelly mentioned earlier, life is built out of
• 19:06
  Speaker 1: only one of these things. Life has chosen one of these.
• 19:10
  Speaker 1: We are all built out of left handed amino acids,
• 19:14
  Speaker 1: the things that make up all living creatures on earth,
• 19:17
  Speaker 1: including the microbes that infect us are all made out
• 19:20
  Speaker 1: of one of these things and not the other one,
• 19:22
  Speaker 1: which is really peculiar.
• 19:24
  Speaker 2: Yeah, wouldn't we have a lot more options for the
• 19:27
  Speaker 2: kinds of amino acids and stuff we could make if
• 19:29
  Speaker 2: we had both kiralities. But I guess we already could
• 19:31
  Speaker 2: make more amino acids than are typically used by organisms,
• 19:35
  Speaker 2: So maybe we don't need that many more amino acids.
• 19:38
  Speaker 1: Yeah, because the different chiralities don't work together, like these
• 19:41
  Speaker 1: things have to fit together really precisely. I think of
• 19:44
  Speaker 1: these little molecules as little machines, you know, that do
• 19:47
  Speaker 1: something biochemically. This one builds that, and this one builds
• 19:50
  Speaker 1: the other thing, and this one rotates this thing. They're
• 19:52
  Speaker 1: all like, you know, I imagine little legos in my
• 19:55
  Speaker 1: head because I'm not very good chemistry, and they have
• 19:58
  Speaker 1: to have their particular arrangement to do their job. You
• 20:00
  Speaker 1: can't just replace it with the opposite kirality and expect
• 20:03
  Speaker 1: it to do the same thing, especially if everybody else
• 20:06
  Speaker 1: is the different kirality. It might work if you flipped
• 20:09
  Speaker 1: all of it right. You took all of life from
• 20:11
  Speaker 1: left to right, and you can make a right handed version.
• 20:13
  Speaker 1: I think That's one of the questions Eric Church was
• 20:15
  Speaker 1: hoping to answer, like is it really arbitrary? Could life
• 20:18
  Speaker 1: work if everything was right handed? It seems like it should,
• 20:22
  Speaker 1: But it's fascinating that you can't mix them right like
• 20:25
  Speaker 1: a left handed person can't eat right handed food, or
• 20:28
  Speaker 1: couldn't have a baby with a right handed person, you know,
• 20:31
  Speaker 1: like their biochemistries just don't interact. It's fascinating.
• 20:35
  Speaker 2: Yeah, you said Eric Church, but I think you met
• 20:37
  Speaker 2: George Church. Oh sorry, yeah, that's all right. So is
• 20:39
  Speaker 2: this kind of like if you have a iPhone you
• 20:43
  Speaker 2: can't use the apps made for Android? Could it just
• 20:46
  Speaker 2: be that life sort of started in one direction and
• 20:49
  Speaker 2: then some piece of machinery for life came into existence
• 20:53
  Speaker 2: that was really good, but only the right handed molecules
• 20:56
  Speaker 2: could be used with that piece of machinery. And that's
• 20:59
  Speaker 2: just it got the ball rolling and the left handed
• 21:02
  Speaker 2: ones could never compete. Sorry, Android users, And that's why
• 21:05
  Speaker 2: we have this preference for one. It was like some
• 21:07
  Speaker 2: early machinery used one chirality and not the other.
• 21:10
  Speaker 1: Yeah, so we actually don't know the answer to that question.
• 21:12
  Speaker 1: We don't know like does it have to be this way?
• 21:14
  Speaker 1: Is there something about left handed molecules that are better
• 21:18
  Speaker 1: at forming life, or something fundamentally by the biochemistry of
• 21:21
  Speaker 1: life that prefers left handedness. That would be weird, right,
• 21:24
  Speaker 1: because there isn't really a difference, it's just reflection. Fundamentally,
• 21:29
  Speaker 1: the universe shouldn't prefer one or the other, but it
• 21:32
  Speaker 1: kind of seems to And you're right that once you
• 21:34
  Speaker 1: choose one, you're stuck. Right. It's sort of like everybody
• 21:37
  Speaker 1: sits down at a dinner party. Are you taking the
• 21:40
  Speaker 1: silverware that's on your left or on your right. Once
• 21:43
  Speaker 1: somebody takes one, everybody's gonna make the same choice, or
• 21:45
  Speaker 1: you get clashes, right, Or as you say, once you're
• 21:48
  Speaker 1: in the Apple ecosphere, then you got to have all
• 21:51
  Speaker 1: Apple devices where they don't work together. So we think
• 21:54
  Speaker 1: that once you choose one, you're stuck with it. We
• 21:56
  Speaker 1: don't know if it was just like a random choice,
• 21:58
  Speaker 1: like that first living thing could have been left or right,
• 22:01
  Speaker 1: and it was just randomly left and now we're all
• 22:04
  Speaker 1: stuck left, or if there's a reason it has to
• 22:06
  Speaker 1: be left or more likely to be left, and just
• 22:09
  Speaker 1: everything has followed from that.
• 22:11
  Speaker 2: Yeah, but it feels to me like there's no reason
• 22:14
  Speaker 2: why you couldn't have had a branch of life that
• 22:16
  Speaker 2: started right and that a branch of life that started left.
• 22:20
  Speaker 2: Like you know, the same trick could have been come
• 22:22
  Speaker 2: upon for both kyalities and then you sort of radiate
• 22:25
  Speaker 2: out from there, and then.
• 22:26
  Speaker 1: There was an epic battle right versus left.
• 22:29
  Speaker 2: Yeah, I'm sure the right handed would win.
• 22:33
  Speaker 1: But this is not something we even knew until like
• 22:35
  Speaker 1: one hundred and fifty years ago, and it was Louis
• 22:38
  Speaker 1: Pasteur who discovered this. He was studying this byproduct of
• 22:42
  Speaker 1: wine fermentation, tartaric acid, and he noticed that there were
• 22:46
  Speaker 1: two types of crystals that were made. There were mirror
• 22:48
  Speaker 1: images of each other. So he was trying to synthesize
• 22:51
  Speaker 1: this thing, because you can synthesize these chemicals and you
• 22:54
  Speaker 1: can make right or left, but then you discover out
• 22:56
  Speaker 1: in a natural world you only ever find left. So
• 22:59
  Speaker 1: he discovered, oh, this is a difference if I make
• 23:01
  Speaker 1: it myself in the lab versus if I like find
• 23:04
  Speaker 1: it from nature. And he was able to pin this
• 23:07
  Speaker 1: down using polarized light to figure out what the chemical
• 23:10
  Speaker 1: structure of these things were. So this is something we've
• 23:13
  Speaker 1: only known about for one hundred and fifty years and
• 23:15
  Speaker 1: people have been trying to figure out, like what is
• 23:17
  Speaker 1: the cause of it for much longer than that. There
• 23:19
  Speaker 1: are some speculative answers. I read a paper that suggested
• 23:23
  Speaker 1: that there could be something about how magnets formed in
• 23:26
  Speaker 1: the Earth that prefers left handed chirality, like the magnetic
• 23:30
  Speaker 1: field of the Earth generates some preference for the left
• 23:34
  Speaker 1: handed versions versus the right handed versions. But it's very speculative,
• 23:38
  Speaker 1: and this is super cool. We just learned from an
• 23:41
  Speaker 1: amazing mission that went out and sampled an asteroid Bendu
• 23:45
  Speaker 1: brought stuff back to Earth we could study it. In
• 23:48
  Speaker 1: that sample, there are equal mixtures of left and right
• 23:51
  Speaker 1: handed organic chemicals, So huge clue because life on Earth
• 23:55
  Speaker 1: prefers the left handed ones, but the basic ingredients for
• 23:59
  Speaker 1: left or right handed life seem to be out there
• 24:02
  Speaker 1: in the universe.
• 24:03
  Speaker 2: So when you do industrial processes like Pastura was doing,
• 24:07
  Speaker 2: you get both kinds? Do you get both kinds evenly?
• 24:11
  Speaker 2: Because if so, it feels like the magnet's answer doesn't work.
• 24:14
  Speaker 1: You're right. But I think the idea is that there
• 24:16
  Speaker 1: could be these magnetic surfaces essentially that are made that
• 24:20
  Speaker 1: better bind to the left handed bits, and then essentially
• 24:23
  Speaker 1: bring them together, gather them together so that they can
• 24:25
  Speaker 1: make more complex molecules. So you might get more complex
• 24:28
  Speaker 1: left handed structures faster than you get complex right handed structures,
• 24:32
  Speaker 1: even if you have the same relative abundance of the precursors.
• 24:36
  Speaker 1: That basically it creates a playground where the lefty bits
• 24:39
  Speaker 1: come together to make the complex structures you need for life.
• 24:42
  Speaker 2: I mean that feels testable.
• 24:44
  Speaker 1: Yes, this is totally testable. And I read an article
• 24:46
  Speaker 1: from Science in twenty twenty three where they do experiments
• 24:48
  Speaker 1: and they can produce this kind of effect. That doesn't
• 24:52
  Speaker 1: mean that it's the reason why life is left handed.
• 24:54
  Speaker 1: It's just like there is in some sense something that
• 24:58
  Speaker 1: prefers left handed chemistry to right handed chemistry right, and
• 25:02
  Speaker 1: we do see other hints of that in the universe,
• 25:04
  Speaker 1: like there are other parts of the universe that seem
• 25:06
  Speaker 1: to prefer left handedness over right handedness, like particle physics.
• 25:11
  Speaker 1: Particle physics has a basic preference for left handedness over
• 25:15
  Speaker 1: right handedness, And after we dig into it, we can
• 25:18
  Speaker 1: come back and make the connection. People think that maybe
• 25:21
  Speaker 1: high speed particles from space could have influenced the left
• 25:25
  Speaker 1: or right handedness of life, on Earth.
• 25:27
  Speaker 2: We talked about amino acids being left handed. Amino acids
• 25:30
  Speaker 2: come together to form proteins. Are there other things that
• 25:34
  Speaker 2: are important to biology that also have a handedness?
• 25:39
  Speaker 1: Well, I think the left handed nature of the amino
• 25:41
  Speaker 1: acids means that the sugars they make are right handed,
• 25:45
  Speaker 1: because that's the kind of thing that a left handed
• 25:47
  Speaker 1: amino acid will make. So those bits are sort of complementary.
• 25:51
  Speaker 1: So there are some parts of our life biochemistry that
• 25:54
  Speaker 1: are right handed that the amino acids are all left handed,
• 25:57
  Speaker 1: so we call it left handed, if that makes sense.
• 26:00
  Speaker 2: The amino acids are the building blocks. You expect the
• 26:04
  Speaker 2: things that the amino acids make, like proteins and sugars,
• 26:08
  Speaker 2: to be the opposite handedness because of how they all
• 26:11
  Speaker 2: get put together.
• 26:13
  Speaker 1: Yeah, exactly, Okay, And you can actually exploit that, as
• 26:15
  Speaker 1: you were talking about earlier with flavors. Some artificial sweeteners
• 26:20
  Speaker 1: exploit this fact. Despite being a sugar and tasting sweet,
• 26:23
  Speaker 1: they can go through your body without being metabolized because
• 26:26
  Speaker 1: they have the wrong handedness. So that's kind of cool.
• 26:29
  Speaker 2: That is kind of cool. I feel like there's a
• 26:31
  Speaker 2: little voice in the back of my head saying wasn't
• 26:34
  Speaker 2: there a study about how maybe they're not so good
• 26:35
  Speaker 2: for your body? But I'm not an expert on that. Anyway,
• 26:38
  Speaker 2: it might be worth looking up.
• 26:39
  Speaker 1: And we are not making any medical recommendations here, folks.
• 26:42
  Speaker 2: Amen, All right, So we've discussed that amino acids are
• 26:46
  Speaker 2: building blocks of other things, and that the left handed
• 26:49
  Speaker 2: building blocks produce right handed other things. So let's go
• 26:53
  Speaker 2: down another level before amino acids, or maybe multiple levels
• 26:57
  Speaker 2: before amino acids, down to particles. I knew that amino
• 27:00
  Speaker 2: acids were left handed. Could you predict the handedness of
• 27:03
  Speaker 2: particles because it alternates between levels.
• 27:05
  Speaker 1: Oh, it's a great question. We don't know the answer
• 27:07
  Speaker 1: to that. And we knew one hundred and fifty years
• 27:09
  Speaker 1: ago that amino acids were left handed. But physicists were
• 27:13
  Speaker 1: confident that the universe fundamentally at the particle level had
• 27:16
  Speaker 1: to be balanced, that it would be crazy if the
• 27:19
  Speaker 1: universe itself was left handed in some way, like why
• 27:22
  Speaker 1: would it prefer one direction over the other? That was nonsense,
• 27:26
  Speaker 1: And people did some tests early on, like let's see
• 27:28
  Speaker 1: if electromagnetism is symmetric, is there any preference for photons
• 27:32
  Speaker 1: to go in one direction? Or the other and they're
• 27:34
  Speaker 1: like no. And they did tests on another force as well,
• 27:37
  Speaker 1: the strong force, but people were very confident that the
• 27:39
  Speaker 1: universe didn't prefer left or right handed. And when we
• 27:43
  Speaker 1: talk about particles, we have to be a little bit
• 27:44
  Speaker 1: careful what we mean by left or right handed particles
• 27:47
  Speaker 1: because the definition we gave earlier, you have like three directions.
• 27:49
  Speaker 1: That makes sense for building molecules. Right, you're putting these
• 27:52
  Speaker 1: things together. You can imagine like balls and sticks, and
• 27:55
  Speaker 1: you're making something which doesn't reflect in the mirror. But
• 27:58
  Speaker 1: particles we don't think about is having extent. Right, they're
• 28:00
  Speaker 1: just like dots. So what do we mean by left
• 28:03
  Speaker 1: or right handed when it comes to particles, Well, particles
• 28:06
  Speaker 1: don't have an extent, but they do have two different arrows.
• 28:10
  Speaker 1: You can have particles that can be moving in one direction,
• 28:13
  Speaker 1: so that's the momentum of the particle. Right, imagine an
• 28:15
  Speaker 1: electron is flying through space. You could put an arrow
• 28:18
  Speaker 1: from where it was to where it's going. That's one arrow.
• 28:22
  Speaker 1: The other arrow of the particle is its spin. Electrons
• 28:25
  Speaker 1: can be spin up or spin down, so you can
• 28:27
  Speaker 1: think of that as another little arrow, and that arrow
• 28:30
  Speaker 1: can either be aligned with its motion, in which case
• 28:32
  Speaker 1: we call it a right handed electron or not aligned,
• 28:35
  Speaker 1: so pointing away from the direction it's moving. So if
• 28:39
  Speaker 1: your two arrows of your spin and your momentum point
• 28:41
  Speaker 1: in the same direction, we call you a right handed particle,
• 28:44
  Speaker 1: and if they're not aligned, we call you a left
• 28:46
  Speaker 1: handed particle.
• 28:47
  Speaker 2: Does it change the way we think about this when
• 28:50
  Speaker 2: we think about electrons as waves instead of particles.
• 28:53
  Speaker 1: Yeah, that's a great question, and we should always keep
• 28:55
  Speaker 1: in our minds that electrons are not tiny little balls
• 28:58
  Speaker 1: or even dots, but they are guided by the wave function. Right,
• 29:01
  Speaker 1: So what happens to a particle is determined by this
• 29:05
  Speaker 1: wave its outcome, which makes some of this stuff probabilistic. Right, Like,
• 29:09
  Speaker 1: an electron might not have a definan spin. It might
• 29:11
  Speaker 1: be maybe this or maybe that right. But some processes
• 29:15
  Speaker 1: have to produce left or right handed electrons, which means
• 29:18
  Speaker 1: you know in advance, like this one doesn't have a
• 29:20
  Speaker 1: probability to be left or right. It has to be
• 29:22
  Speaker 1: left or it has to be right in order to
• 29:23
  Speaker 1: balance with other bits. So, for example, if you have
• 29:27
  Speaker 1: two electrons produced opposite each other, you know their momenta
• 29:30
  Speaker 1: point opposite to each other, and you know, their spin
• 29:33
  Speaker 1: also have to be opposite to each other, which means
• 29:36
  Speaker 1: they're either both right handed or they're both left handed,
• 29:39
  Speaker 1: and you might not know that in advance. So in
• 29:40
  Speaker 1: that case, for example, your electron is going to be
• 29:42
  Speaker 1: fifty percent left handed and fifty percent right handed, but
• 29:45
  Speaker 1: they have to be the same right if they're produced
• 29:47
  Speaker 1: the same. So yeah, the wave nature gives you a
• 29:50
  Speaker 1: probabilistic aspect to all these particles for sure.
• 29:53
  Speaker 2: All right, got it?
• 29:54
  Speaker 1: And so this is what we call handedness for particles.
• 29:56
  Speaker 1: Sometimes they call it helicity. And one important caveat here
• 29:59
  Speaker 1: is that this isn't actually something that's exact, because the
• 30:03
  Speaker 1: momentum of a particle depends on your velocity. Like you
• 30:06
  Speaker 1: can imagine flipping the direction of a particle by zooming
• 30:10
  Speaker 1: past it in a spaceship. So now instead of moving
• 30:13
  Speaker 1: one direction, it looks like it's moving the other direction
• 30:15
  Speaker 1: that basically flips its momentum. So we actually only talk
• 30:19
  Speaker 1: about the handedness of particles that have no mass or
• 30:23
  Speaker 1: very very very low mass, precisely because then you can't
• 30:26
  Speaker 1: pass them in a spaceship. To be very technical, this
• 30:29
  Speaker 1: handedness is actually an internal label it's not a physical thing.
• 30:33
  Speaker 1: So the direction of the two arrows, it's like an
• 30:35
  Speaker 1: approximate way to think about the handedness of the particles.
• 30:38
  Speaker 1: But fundamentally it's some internal label we don't understand the
• 30:41
  Speaker 1: way like charge is. So now I just think about
• 30:44
  Speaker 1: these particles as having like a little label on them.
• 30:46
  Speaker 1: Some of them have an L and some of them
• 30:47
  Speaker 1: have an R. And we thought for a long time,
• 30:49
  Speaker 1: like the universe shouldn't predict either one, Like if you
• 30:52
  Speaker 1: have some particle physics process, it should make the same
• 30:55
  Speaker 1: number of right and left handed electrons in the early universe.
• 30:58
  Speaker 1: You should have gotten an equal mixture, right in the
• 31:00
  Speaker 1: same way we talked earlier about preferring symmetry. And then
• 31:04
  Speaker 1: it was in the nineteen sixties that people realized, hey,
• 31:06
  Speaker 1: you know, we think that the universe is balanced. We
• 31:10
  Speaker 1: think that there is a symmetry here, and we've checked
• 31:12
  Speaker 1: it for a couple of things, but nobody's actually gone
• 31:15
  Speaker 1: and done the test to see if the weak nuclear
• 31:17
  Speaker 1: force prefers left or right handed particles equally or not.
• 31:22
  Speaker 2: I'm just going to point out that the biologist had
• 31:24
  Speaker 2: figured out the importance of this one hundred years earlier. Apparently.
• 31:28
  Speaker 2: I'm glad you guys caught up though, So go ahead.
• 31:31
  Speaker 1: That's right. Physics is always one hundred years behind biology.
• 31:33
  Speaker 1: That's the way it works. So there was this exciting
• 31:38
  Speaker 1: moment in the late fifties where people realized, oh my gosh,
• 31:41
  Speaker 1: nobody's tested this before, and it's not actually that hard
• 31:45
  Speaker 1: to do. So then this amazing scientist, chan hin Wu
• 31:48
  Speaker 1: realized in the late fifties, actually this wasn't difficult to test.
• 31:53
  Speaker 1: This is something you could figure out. So she decided
• 31:56
  Speaker 1: to skip her Christmas holiday, she sent her husband on
• 31:59
  Speaker 1: along and say, I'm going to stay in the lab
• 32:01
  Speaker 1: and figure this out. You know when you get like
• 32:03
  Speaker 1: excited about something. And she put the experiment together. She
• 32:06
  Speaker 1: got a bunch of cobalt atoms to spin only in
• 32:09
  Speaker 1: one direction, and then she measured the angles that the
• 32:11
  Speaker 1: electrons came out. And this was a great test of
• 32:14
  Speaker 1: whether the universe preferred one direction or another because the
• 32:17
  Speaker 1: electrons were made purely by the weak force. And she
• 32:20
  Speaker 1: discovered not only was it out of balance, but it
• 32:23
  Speaker 1: was completely out of balance. It wasn't like the electrons
• 32:25
  Speaker 1: were fifty one forty nine one direction. It was like
• 32:28
  Speaker 1: one hundred zero, like the electrons would only go in
• 32:32
  Speaker 1: one direction. It turns out that the weak force only
• 32:35
  Speaker 1: makes and interacts with left handed particles. It like completely
• 32:39
  Speaker 1: doesn't play with right handed particles at all. So all
• 32:42
  Speaker 1: the other forces don't care. Electromagnetism, the strong force no preference,
• 32:46
  Speaker 1: but the weak force only plays with left handed particles.
• 32:50
  Speaker 1: This was a really shocking discovery.
• 32:52
  Speaker 2: And after the break we are going to one hundred
• 32:54
  Speaker 2: percent explain to you why that is. And we're back
• 33:14
  Speaker 2: just kidding. We never have one hundred percent explanations for anything.
• 33:18
  Speaker 2: What is our current state of not understanding this phenomenon, Danniel.
• 33:23
  Speaker 1: It's not something that we understand, it's something that we describe,
• 33:25
  Speaker 1: something we see in the universe. We can incorporate it
• 33:28
  Speaker 1: into the mathematics of our theory, like the standard model
• 33:32
  Speaker 1: of particle physics that describes how particles interact and how
• 33:35
  Speaker 1: they're created and all. This kind of stuff naturally has
• 33:37
  Speaker 1: left and right handed particles, and the mathematics of the
• 33:40
  Speaker 1: weak force allow it to only interact with left handed particles.
• 33:44
  Speaker 1: But again we don't know why that is. You know,
• 33:46
  Speaker 1: the other forces treat the particles completely equally, and the
• 33:50
  Speaker 1: Higgs force unifies these things, Like the Higgs force combines
• 33:54
  Speaker 1: the left handed and right handed version of particles into
• 33:58
  Speaker 1: one that we see and know and love and has mass.
• 34:00
  Speaker 2: Where does it get the right handed versions if it's
• 34:03
  Speaker 2: combining them. So it gets the right handed versions from
• 34:05
  Speaker 2: other forces and combines them.
• 34:08
  Speaker 1: Okay, yeah, so you can make right handed electrons. You
• 34:11
  Speaker 1: just can't use the weak force to do it. You
• 34:13
  Speaker 1: can use the electromagnetic force to make right handed electrons,
• 34:16
  Speaker 1: no problem. Oh, but those will not interact with W
• 34:19
  Speaker 1: bosons and z bosons and stuff like that. It's really weird.
• 34:23
  Speaker 1: And if we didn't have the weak force, we never
• 34:26
  Speaker 1: would have discovered that our universe for some reason, seems
• 34:29
  Speaker 1: to be left handed at a particle level.
• 34:31
  Speaker 2: If you were to like rank the forces in terms
• 34:34
  Speaker 2: of like how common they are in the universe, I
• 34:37
  Speaker 2: actually don't know the right way to rank these, Like
• 34:39
  Speaker 2: how important is the weak force?
• 34:42
  Speaker 1: Amazing question? Well, you know, the most powerful force is
• 34:46
  Speaker 1: a strong force, and then electromagnetism, then the weak force,
• 34:49
  Speaker 1: then gravity if it's a force at all. But the
• 34:51
  Speaker 1: weak force, in some way is so much more complex
• 34:54
  Speaker 1: and fascinating than any of the other forces. It's got
• 34:57
  Speaker 1: extra particles like it has the W and the Z particles,
• 35:01
  Speaker 1: all these particles needed to do its stuff, and it's
• 35:04
  Speaker 1: so much more complicated, and it's responsible for the Higgs boson.
• 35:08
  Speaker 1: So it's pretty important and weird, and in that sense
• 35:12
  Speaker 1: it's valuable because it gives us insight into the nature
• 35:14
  Speaker 1: of the universe. You know, it does. It's weird stuff.
• 35:17
  Speaker 1: If everything was simple and clean, that we wouldn't learn
• 35:19
  Speaker 1: as much about the universe. It's the ugly messes that
• 35:22
  Speaker 1: teach us something about how the universe is actually working.
• 35:25
  Speaker 2: I feel like that's a lesson for my life somehow.
• 35:27
  Speaker 2: But go ahead.
• 35:30
  Speaker 1: There's just such a shocking discovery that the theorist that
• 35:32
  Speaker 1: suggested it won the Nobel Prize, just like a couple
• 35:35
  Speaker 1: of years later. Unfortunately, chinchin Wu, who did the experiment,
• 35:39
  Speaker 1: she didn't get the Nobel Prize. Another example of the
• 35:42
  Speaker 1: Nobel not treating lady scientists equally. Unfortunately, there's an imbalance
• 35:46
  Speaker 1: for you.
• 35:47
  Speaker 2: Yeah, that sucks. She's still alive.
• 35:49
  Speaker 1: She is no longer alive, but we're gonna have a
• 35:51
  Speaker 1: whole episode about her next year, and we're going to
• 35:54
  Speaker 1: talk to her granddaughter, who I grew.
• 35:56
  Speaker 2: Up with Oh fantastic, all right, I'm looking forward to that.
• 35:59
  Speaker 2: So the weak force produces left handed electrons, and then
• 36:04
  Speaker 2: somehow we end up with left handed amino acids. Let's
• 36:07
  Speaker 2: talk about the intermediate scale there. How do we think
• 36:09
  Speaker 2: scale up between left handed electrons and left handed amino acids.
• 36:14
  Speaker 1: Yeah, we don't know. There's a lot of speculation because
• 36:17
  Speaker 1: this smells like a weird coincidence, Like, how is it
• 36:21
  Speaker 1: that the universe produces more left handed particles and right
• 36:24
  Speaker 1: handed particles and life is made out of left handed
• 36:27
  Speaker 1: amino acids? Is that a coincidence or is there a reason?
• 36:30
  Speaker 1: So there's a theory that particles from space when they
• 36:34
  Speaker 1: smash into the atmosphere cosmic rays, they produce a shower
• 36:38
  Speaker 1: of particles, and the weak force is involved, which means
• 36:41
  Speaker 1: that it makes more left handed particles than right handed particles.
• 36:45
  Speaker 1: And then dot dot dot a bunch of stuff that's
• 36:47
  Speaker 1: not really plausible. Maybe that makes more left handed amino acids.
• 36:51
  Speaker 1: And you know, there are papers I've read about this
• 36:53
  Speaker 1: and I always come away from them going like, I
• 36:55
  Speaker 1: don't think. So it's like a real effort to draw
• 36:59
  Speaker 1: a line between these things, because it's hard to imagine
• 37:02
  Speaker 1: how a left handed muon is going to somehow make
• 37:06
  Speaker 1: more amino acids that are left handed. Like, yes, the
• 37:10
  Speaker 1: muons come in and they smash into stuff, and there's
• 37:12
  Speaker 1: still an important part of life today, you know, breaking
• 37:14
  Speaker 1: amino acids and creating mutations and all sorts of stuff
• 37:18
  Speaker 1: is important for evolution. But we don't have a microphysical
• 37:21
  Speaker 1: explanation for why having more left handed muons could create
• 37:25
  Speaker 1: more left handed amino acids or encourage them to form
• 37:28
  Speaker 1: life or whatever make them more resilient. I don't know,
• 37:32
  Speaker 1: because the weak force is very, very weak. You know,
• 37:34
  Speaker 1: most of the time when a muon interacts with you,
• 37:36
  Speaker 1: it's interacts electromagnetically, so it would be a very subtle
• 37:40
  Speaker 1: effect if it even did exist. So really still an
• 37:43
  Speaker 1: open question. We don't understand whether there's any connection between
• 37:47
  Speaker 1: the fundamental left handed preference of the weak force and
• 37:51
  Speaker 1: the left handed nature of life on Earth.
• 37:53
  Speaker 2: Okay, so there's an important question that one of our
• 37:56
  Speaker 2: listeners can answer, one of our young listeners. Okay, so
• 38:00
  Speaker 2: we know we have handedness in some cases, we don't
• 38:02
  Speaker 2: know why we have it. We don't know the implications,
• 38:05
  Speaker 2: as you scale, is there important symmetry in other areas
• 38:10
  Speaker 2: that gets broken.
• 38:11
  Speaker 1: Yeah, so great question. This inspires us to look for
• 38:14
  Speaker 1: violations of symmetry elsewhere in the universe. Right, and we
• 38:17
  Speaker 1: know already that the universe isn't always in balance, like,
• 38:20
  Speaker 1: for example, we know that there are two different kinds
• 38:23
  Speaker 1: of matter in the universe, matter and antimatter. Antimatter is
• 38:27
  Speaker 1: like the reflection of matter, where everything has the opposite charge.
• 38:30
  Speaker 1: So we have electrons. We can also make positrons, which
• 38:33
  Speaker 1: are just like electrons, but they have the opposite charge.
• 38:35
  Speaker 1: And you can make anti protons and anti neutrons and
• 38:38
  Speaker 1: there's nothing really anti about them except that they're not
• 38:42
  Speaker 1: our kind of matter. So you know, you could we think,
• 38:45
  Speaker 1: maybe build life out of anti electrons and anti protons
• 38:49
  Speaker 1: to make anti people or whatever. We don't really know
• 38:52
  Speaker 1: that for sure, but the laws of physics so far
• 38:55
  Speaker 1: suggest that that's possible. But the universe has made more
• 38:58
  Speaker 1: of matter than antimatter.
• 39:00
  Speaker 2: I watched too many sci fi movies. I'm under the
• 39:03
  Speaker 2: impression that if matter and antimatter interact, they explode or
• 39:07
  Speaker 2: consume each other in some way, Like could both of
• 39:09
  Speaker 2: these things exist in the same universe? Or does one
• 39:11
  Speaker 2: have to win.
• 39:13
  Speaker 1: They can't exist near each other because they interact very strongly.
• 39:16
  Speaker 1: And so for example, if you have an electron and
• 39:18
  Speaker 1: apostles near each other, they will attract each other and
• 39:20
  Speaker 1: they will annihilate and give you photons. And it's a
• 39:23
  Speaker 1: very efficient conversion of energy from mass to radiation. So
• 39:28
  Speaker 1: for example, if you have a gram of matter like
• 39:30
  Speaker 1: a raisin and a gram of antimatter like an anti raasin,
• 39:34
  Speaker 1: and you bring them together, you get about as much
• 39:36
  Speaker 1: energy as a nuclear bomb just out of two grams
• 39:39
  Speaker 1: of matter and antimatter. So yes, you can't have matter
• 39:42
  Speaker 1: based life and antimatter based life on the same planet,
• 39:46
  Speaker 1: but you could have, for example, matter galaxies and antimatter galaxies. Right,
• 39:51
  Speaker 1: they don't have to touch each other. That is floating
• 39:53
  Speaker 1: in space saying hi. But we're pretty sure that all
• 39:56
  Speaker 1: the galaxies in the universe are matter galaxies, not anti
• 39:59
  Speaker 1: matter g galaxies. And we can actually test this a
• 40:02
  Speaker 1: little bit because galaxies shoot out particles. All the stars
• 40:06
  Speaker 1: and the black holes are emitting radiation and they shoot
• 40:09
  Speaker 1: out electrons for example, and if there were anti galaxies,
• 40:12
  Speaker 1: they would shoot out anti electrons and where those meet
• 40:16
  Speaker 1: you would see these great flashes of light where the
• 40:18
  Speaker 1: electrons and the anti electrons were meeting, and we don't
• 40:21
  Speaker 1: see any of that. We don't see like huge curtains
• 40:23
  Speaker 1: of light between galaxies, which suggests that at least as
• 40:26
  Speaker 1: far as we can see, everything is made of matter.
• 40:29
  Speaker 1: So that's an important asymmetry in the universe, again, one
• 40:32
  Speaker 1: we don't understand. We think probably in the Big Bang
• 40:36
  Speaker 1: there was an equal amount of matter and antimatter, but
• 40:40
  Speaker 1: something preferred matter because otherwise it would have all just
• 40:42
  Speaker 1: gone away and turned into a universe filled with light
• 40:46
  Speaker 1: and no matter. So there's a preference there for matter.
• 40:49
  Speaker 1: It's just an example. We don't know that it's connected
• 40:51
  Speaker 1: to right or left handed. We call one matter and
• 40:53
  Speaker 1: the other antimatter. It's just an example of how the
• 40:56
  Speaker 1: universe sometimes seems to make one choice and not the
• 40:59
  Speaker 1: other for reasons we don't understand.
• 41:02
  Speaker 2: All right, Well, so first of all, I think it's
• 41:03
  Speaker 2: important to note that I'm on team anti Raisin.
• 41:07
  Speaker 1: That you like the golden raisins instead, I don't like
• 41:10
  Speaker 1: any raisins.
• 41:10
  Speaker 2: No raisins, no raisin. Okay, yeah, team anti Razin.
• 41:14
  Speaker 1: But how do you feel about grapes? You like grapes
• 41:16
  Speaker 1: but no raisins.
• 41:17
  Speaker 2: I'm pro grapes really interesting.
• 41:19
  Speaker 1: Are you anti dried fruit in general? No?
• 41:21
  Speaker 2: Dried mangoes? Those are great?
• 41:22
  Speaker 1: Oh man, we got to convert you.
• 41:24
  Speaker 2: This is really really important.
• 41:26
  Speaker 1: Is it just because you think raises ruined oatmeal cookies?
• 41:28
  Speaker 1: Because you'd be right about that.
• 41:30
  Speaker 2: Yeah, that's like ninety percent of why I have trust issues.
• 41:35
  Speaker 2: So the Big Bang had to have resulted in a
• 41:37
  Speaker 2: preference for one or the other, right, because otherwise it
• 41:39
  Speaker 2: would have all just like blown up at that point
• 41:42
  Speaker 2: when it was all compressed.
• 41:43
  Speaker 1: Well, either more matter was made in those early moments
• 41:47
  Speaker 1: than anti matter, and then when they annihilated, you get
• 41:51
  Speaker 1: the massive matter left over. So either there's some early
• 41:53
  Speaker 1: baked in preference for matter over antimatter, or it was
• 41:57
  Speaker 1: symmetric at the beginning and there's some process which then
• 42:00
  Speaker 1: prefers matter to antimatter. And we have a few clues.
• 42:03
  Speaker 1: We've discovered one or two little processes that prefer making
• 42:06
  Speaker 1: matter to antimatter, and that was sort of fascinating and
• 42:09
  Speaker 1: surprising and let to more Nobel prizes. These things are
• 42:12
  Speaker 1: called CP violation if anybody wants to dig deeper into them,
• 42:15
  Speaker 1: But they're not enough to explain it. They're like tiny
• 42:17
  Speaker 1: little effects. It can't explain the size to the effect
• 42:20
  Speaker 1: that we see in the universe. So this basic question,
• 42:22
  Speaker 1: this asymmetry in the universe, we still don't have an
• 42:25
  Speaker 1: answer to. But just to be clear again, it's not
• 42:27
  Speaker 1: directly connected to left handed versus right handed whether the
• 42:31
  Speaker 1: universe is symmetric. It's just whether the universe is symmetric
• 42:34
  Speaker 1: in a mirror. It's just another example of how the
• 42:37
  Speaker 1: universe doesn't have to be balanced right. It can pick
• 42:40
  Speaker 1: one or the other, we think, and we just don't
• 42:42
  Speaker 1: understand why it does or whether it did. But we
• 42:45
  Speaker 1: can think about whether the universe and the Big Bang
• 42:47
  Speaker 1: itself was symmetric from a left versus right handed point
• 42:51
  Speaker 1: of view, Like when we talk about making those three vectors,
• 42:54
  Speaker 1: is there something in the universe that really prefers those
• 42:57
  Speaker 1: fundamentally at the level of the structure of the universe self,
• 43:00
  Speaker 1: not just the particles or the amino acids or dogs
• 43:04
  Speaker 1: or this kind of stuff. And we can think about
• 43:06
  Speaker 1: this by looking at the relationships between galaxies. There's this
• 43:10
  Speaker 1: really amazing study people did last year where they basically
• 43:14
  Speaker 1: just looked at groups of four galaxies and decided whether
• 43:18
  Speaker 1: they would call them left handed or right handed. So
• 43:20
  Speaker 1: remember the example of your fingers, right, you have three fingers,
• 43:24
  Speaker 1: so three tips, and there's also the point where they
• 43:27
  Speaker 1: all meet, so you have sort of like four points there.
• 43:30
  Speaker 1: So if you have four points, you can say is
• 43:32
  Speaker 1: this a left handed grouping or right handed grouping? So
• 43:36
  Speaker 1: they looked at all the galaxies that they could find
• 43:39
  Speaker 1: over a million examples in this one study, and they
• 43:42
  Speaker 1: grouped them into clusters of four and then decided is
• 43:45
  Speaker 1: this a left handed grouping or right handed grouping? And
• 43:48
  Speaker 1: they figured like, hey, this is just galaxies strewn out
• 43:51
  Speaker 1: in the universe. We're just assigning left or right handed
• 43:54
  Speaker 1: to these clusters. It should be balanced, right, There should
• 43:57
  Speaker 1: be no reason why you would get like more right
• 44:00
  Speaker 1: handed or left handed clusters. But what they found is
• 44:04
  Speaker 1: a huge bias towards left handed clusters of galaxies when
• 44:09
  Speaker 1: you group these things together. I know, it makes no sense,
• 44:11
  Speaker 1: like why would you prefer one or the other, But
• 44:14
  Speaker 1: you know, they had groups check their results. This is
• 44:17
  Speaker 1: the kind of result you sort of hope for in science,
• 44:19
  Speaker 1: but then you're terrified of because then you're like, what,
• 44:21
  Speaker 1: this has got to be wrong. This has been delay
• 44:23
  Speaker 1: my paper.
• 44:24
  Speaker 2: Oh my gosh, did I pick the galaxies arbitrarily? I
• 44:27
  Speaker 2: feel like that it would have to be a hard
• 44:28
  Speaker 2: hard to pick them.
• 44:29
  Speaker 1: Yeah, exactly where they tried every combination, and out of
• 44:32
  Speaker 1: a million galaxies you get a trillion trillion combinations. They
• 44:37
  Speaker 1: make these pyramids, right, like four galaxies make this pyramid,
• 44:41
  Speaker 1: and you can decide whether it's a left or right
• 44:43
  Speaker 1: handed pyramid. And the chances of this being a random
• 44:46
  Speaker 1: fluctuation is one in three hundred billion. So either it's
• 44:51
  Speaker 1: a crazy fluctuation, or it suggests that there's something about
• 44:57
  Speaker 1: the universe, something about the topology, structure, the nature of
• 45:01
  Speaker 1: space and time itself that aligns these galaxies in a
• 45:05
  Speaker 1: more lefty way than a right handed way. It's really
• 45:08
  Speaker 1: a fascinating clue. And it's just like adds to the story,
• 45:11
  Speaker 1: like life is left handed, particles are left handed, something
• 45:15
  Speaker 1: about the structure of galaxies in the universe itself is
• 45:17
  Speaker 1: left handed.
• 45:18
  Speaker 2: No wonder Zach thinks he's so great.
• 45:21
  Speaker 1: It turns out he's right. Science has proved him right.
• 45:25
  Speaker 2: There's got to be something we don't understand in between there.
• 45:27
  Speaker 1: All right, reviewer number two over there, So this is
• 45:31
  Speaker 1: just like a collection of clues that all point towards
• 45:34
  Speaker 1: something that smells suggestive. But it could just be nothing.
• 45:39
  Speaker 1: It could just be here's a bunch of coincidences, you know,
• 45:42
  Speaker 1: left versus right. Whatever the universe just picks randomly. And
• 45:45
  Speaker 1: we live in a multiverse with all different kinds of universes,
• 45:48
  Speaker 1: and some of them have right handed life and right
• 45:50
  Speaker 1: handed particles and left handed galaxy structures. Or maybe there's
• 45:56
  Speaker 1: something deep in the mathematics which really prefers left handed
• 46:00
  Speaker 1: structures and can only work this way, and just we
• 46:03
  Speaker 1: haven't puzzled it out yet. We haven't found the connections
• 46:06
  Speaker 1: between these different layers of leftiness, and we haven't understood
• 46:10
  Speaker 1: what about the nature of the universe requires things to
• 46:13
  Speaker 1: be left handed. It's a fascinating puzzle and the kind
• 46:16
  Speaker 1: of thing I think in one hundred years, I hope
• 46:18
  Speaker 1: we have much more clarity on.
• 46:20
  Speaker 2: Are we currently at the just like scratching our head
• 46:22
  Speaker 2: and pulling out our hair phase, or are they're like
• 46:24
  Speaker 2: four competing hypotheses and we're just waiting for the LHC
• 46:28
  Speaker 2: to give us the answer, Like where are we right now?
• 46:31
  Speaker 1: I think we're in between those two different outcomes. We
• 46:34
  Speaker 1: have some crazy ideas, like people think maybe the thing
• 46:38
  Speaker 1: that came before that early moment of hot density, you know,
• 46:42
  Speaker 1: the inflation and the infloton field and sort of pre
• 46:45
  Speaker 1: Big Bang theories and everything that's pre Big bang very speculative,
• 46:49
  Speaker 1: and that doesn't mean worthless, right, it just means like, hey,
• 46:52
  Speaker 1: we don't really know. We're still in the building phase.
• 46:54
  Speaker 1: We're trying stuff out some of those Maybe we're seated
• 46:58
  Speaker 1: by something that prefers handedness, and people are trying to
• 47:02
  Speaker 1: build left handed ideas into that infloton field with varying success.
• 47:07
  Speaker 1: So we don't have solid predictions that we can use
• 47:10
  Speaker 1: to test any of these ideas. We're just sort of like,
• 47:12
  Speaker 1: maybe this is something, and maybe this is something we
• 47:15
  Speaker 1: should be building into our theories of the pre Big
• 47:17
  Speaker 1: Bang universe. We can try to look deeper into the
• 47:21
  Speaker 1: history of time to try to understand it, Like we
• 47:24
  Speaker 1: hope that gravitational waves from the very very early universe
• 47:28
  Speaker 1: will help illuminate what was going on. You know, we
• 47:31
  Speaker 1: can only see the early universe back to about three
• 47:34
  Speaker 1: hundred and eighty thousand years after that first understood moment
• 47:38
  Speaker 1: because that's the first time the universe was transparent, but
• 47:41
  Speaker 1: there's a lot of stuff going on before the universe
• 47:43
  Speaker 1: was transparent, when it's hot and dense and opaque, and
• 47:46
  Speaker 1: we hope that gravitational waves will give us a window
• 47:49
  Speaker 1: into those moments and maybe this can clue there and
• 47:52
  Speaker 1: the polarity of those gravitational waves to see if they
• 47:55
  Speaker 1: prefer left handed physics to right handed physics, or maybe
• 47:58
  Speaker 1: not right maybe they are perfectly in balance. So this
• 48:02
  Speaker 1: possibility that we could learn something, but that's very subtle physics,
• 48:06
  Speaker 1: and seeing gravitational waves from the very early univers is
• 48:09
  Speaker 1: notoriously tricky. There was an experiment by step two a
• 48:12
  Speaker 1: few years ago that thought it had seen them and
• 48:14
  Speaker 1: had evidence for inflation. Then it turned out to just
• 48:16
  Speaker 1: be dust.
• 48:17
  Speaker 3: Yeah.
• 48:18
  Speaker 2: Yeah, Oh, that's frustrating. It's always pigeon.
• 48:20
  Speaker 1: Poop or dust exactly. Science is hard, people, it's hard,
• 48:27
  Speaker 1: it is, but the mysteries are deep and they are fascinating,
• 48:30
  Speaker 1: and all of these clues tell us like, maybe this
• 48:33
  Speaker 1: is a thread we should pull on that's going to
• 48:35
  Speaker 1: unravel our whole understanding of the universe, or maybe it's
• 48:38
  Speaker 1: just a coin toss in beginning of the universe and
• 48:40
  Speaker 1: it means nothing, and people.
• 48:42
  Speaker 2: Will spend entire careers trying to figure it.
• 48:44
  Speaker 1: Out, and maybe one of you out there will be
• 48:46
  Speaker 1: the one to pull back the veil and help us
• 48:49
  Speaker 1: understand the nature of our own universe.
• 48:51
  Speaker 2: Please do that.
• 48:53
  Speaker 1: Soon, Please soon. I'd love to know the answer.
• 48:56
  Speaker 3: Yeah.
• 48:57
  Speaker 2: Same. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.
• 49:08
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• 49:11
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• 49:14
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• 49:28
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  Speaker 2: and Kuniverse.
• 49:38
  Speaker 1: Don't be shy write to us.