Latest / Daniel and Kelly’s Extraordinary Universe / Does particle spin affect life on Earth?

Transcript

Does particle spin affect life on Earth? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Okay, I realized I've never asked you this. Are you
0:11
Speaker 1: left or right handed? Usually draw with my right hand,
0:15
Speaker 1: so I'm sure you've tried to draw with your other hand.
0:18
Speaker 1: What's that like? It's it's pretty tricky. Yeah, if you're
0:21
Speaker 1: used to doing things with one hand, it's hard to switch. Well,
0:23
Speaker 1: what about driving? Have you ever driven on the left
0:26
Speaker 1: side of the road, you mean, on purpose or against
0:29
Speaker 1: the law or following the laws of Well, you know
0:32
Speaker 1: there are some places in the world where they drive
0:34
Speaker 1: on the other side. I have driven in Australia and England. Yeah,
0:38
Speaker 1: it's pretty tricky, but after a while you get used
0:41
Speaker 1: to it. What would you say is better your left
0:43
Speaker 1: side of the road driving or your left handed drawing. Well,
0:46
Speaker 1: I've fortunately have not had an accident on either side
0:49
Speaker 1: of the road, so the data says that I am
0:52
Speaker 1: equally good. Well, I'm glad you're even handed. That sounds
0:54
Speaker 1: like a left handed compliment, Daniel, I think that's right.
1:00
Speaker 1: Hi am poor handed cartoonists and the creator of PhD comics. Hi,
1:15
Speaker 1: I'm Daniel. I'm a particle physicist and a professor. And
1:18
Speaker 1: you see Irvine and I have tried to do math
1:21
Speaker 1: left handed. I mean you write out math with your
1:24
Speaker 1: left hand. Is that what you mean? Yeah? I try
1:25
Speaker 1: to write out math with my left hand or sometimes
1:27
Speaker 1: upside down. Sometimes when I'm teaching math to my kids,
1:31
Speaker 1: I have to write it so that they can see it,
1:33
Speaker 1: which requires a little bit of awkward gymnastics. But if
1:36
Speaker 1: you use your left hand and maybe it's it's it's normal.
1:40
Speaker 1: If I use my left hand and my handwriting looks
1:42
Speaker 1: as sloppy as theirs. I know people who would aspire
1:44
Speaker 1: to be ambidexterous, so they purposely used the mouths even
1:48
Speaker 1: though they're right handed. They use their mouse but their
1:50
Speaker 1: left hand so that they're you know, are able to
1:52
Speaker 1: do both. How would you give my right arm to
1:54
Speaker 1: be ambidextrous. Well, if you give your right arm, then
1:56
Speaker 1: you wouldn't be ambidexterous. Sounds like you're caught in a paradox.
2:00
Speaker 1: Welcome to a podcast Daniel and Jorge Explain the Universe,
2:02
Speaker 1: a production of I Heart Radio, in which we try
2:05
Speaker 1: to tickle the right side of your brain and the
2:07
Speaker 1: left side of your brain. We want to understand the
2:10
Speaker 1: entire universe, the top half, the bottom half, the left side,
2:13
Speaker 1: the right side, and everything in between even the backside,
2:18
Speaker 1: the backside, the front side, the dark side, and the
2:21
Speaker 1: light side. Every side of the universe deserves to be understood,
2:24
Speaker 1: and we think it's possible. And on this podcast we
2:27
Speaker 1: ask those big questions about the nature of reality, the
2:30
Speaker 1: nature of life, why we are all here, what it
2:32
Speaker 1: all means, how long we will be here, and whether
2:35
Speaker 1: we're alone, and we try to explain all of them
2:37
Speaker 1: to you. And today I want to especially explain things
2:41
Speaker 1: to Walter Bloom, a long time listener of the pod
2:44
Speaker 1: from Switzerland, whose girlfriend Victoria wants to wish him a
2:48
Speaker 1: happy thirty eighth birthday. Happy birthday, Walter, Yeah, it is
2:51
Speaker 1: a big universe to explain. It is a wide universe,
2:55
Speaker 1: full of many sides to it, many different ways that
2:57
Speaker 1: you can look at things, and also many different in
3:00
Speaker 1: ways that things can be put together. There are almost
3:03
Speaker 1: an infinite way for a matter to arrange itself. And
3:05
Speaker 1: one of the joys of physics is figuring out how
3:08
Speaker 1: the universe works, because then we get to ask why.
3:11
Speaker 1: When we discover that we are put together out of
3:13
Speaker 1: time of little particles, we get to wonder, like, why
3:16
Speaker 1: is the universe arranged out of these time little particles.
3:18
Speaker 1: Why does it have these patterns? What does that really mean?
3:21
Speaker 1: The joy physics is really that it's setting us up
3:23
Speaker 1: to ask philosophy questions. Oh, is that the main goal
3:26
Speaker 1: of physics just to be a primer, like a trailer
3:30
Speaker 1: to philosophy, just the opening act for philosophy. Example, what
3:33
Speaker 1: you're saying businesses are just there to warm up the crowd.
3:36
Speaker 1: In the end, I think the almost science really is
3:38
Speaker 1: motivated by philosophy questions. You know, at the heart of
3:41
Speaker 1: almost every science question we ask, there is a why question,
3:45
Speaker 1: which is in the end fundamentally philosophical. Yeah, and we
3:48
Speaker 1: ask these questions not just because it's interesting and fascinating
3:51
Speaker 1: and we understand more about the universe. But sometimes these
3:54
Speaker 1: questions and these issues have a big impact on our daily,
3:57
Speaker 1: everyday lives, even maybe on life itself. Yeah, we notice
4:02
Speaker 1: these patterns in the universe. The universe seems to organize
4:05
Speaker 1: itself in this way and not some other way. We
4:08
Speaker 1: noticed sometimes there are symmetries in the universe, like you
4:10
Speaker 1: could rotate everything and the laws of physics wouldn't change.
4:14
Speaker 1: But also sometimes we notice that there are not symmetries
4:17
Speaker 1: in the universe, that the universe has a strong opinion
4:20
Speaker 1: about how things should be done, and the opposite way
4:22
Speaker 1: just does not happen. Time flows forwards and not backwards,
4:26
Speaker 1: and these are the things that inspire our philosophical musings
4:29
Speaker 1: to wonder what it would be like for universe or
4:32
Speaker 1: time flowed backwards, or what it would be like for
4:34
Speaker 1: universe in the mirror of our universe. Yeah, and so
4:38
Speaker 1: our universe likes to put things together in a particular way,
4:41
Speaker 1: and you can trace sometimes that to the very properties
4:45
Speaker 1: of the smallest particles in the universe, the things that
4:48
Speaker 1: everything is made out of, and some of these properties
4:51
Speaker 1: can have a pretty big impact on what gets formed
4:54
Speaker 1: in the universe and even whether we would be here
4:56
Speaker 1: or not. It does seem sometimes like at the smallest
4:59
Speaker 1: level of the universe, US follows really different rules, really
5:02
Speaker 1: strange quantum rules that don't really affect our lives, Like
5:05
Speaker 1: how a particle moves through space is totally different from
5:08
Speaker 1: how a baseball flies through space. But as you say,
5:11
Speaker 1: sometimes there is a connection. Sometimes we can even find
5:14
Speaker 1: a portal from the timeliest particle to our everyday lives.
5:17
Speaker 1: So to be on the podcast, we will be tackling
5:19
Speaker 1: the question does particle spin affect life on Earth? Are
5:29
Speaker 1: we trying to put a positive spin here on life
5:31
Speaker 1: on Earth? I'm trying to put a positive spin on particles.
5:34
Speaker 1: I'm like, look, particles are relevant. Give me money, is
5:37
Speaker 1: what you're saying. Well, you know that's the philosophy that's
5:40
Speaker 1: underlying all of it. And yes, we're trying to make
5:43
Speaker 1: our science relevant. Do you share any of your funding
5:45
Speaker 1: with philosophers? Philosophers really need funding? I mean, how much
5:48
Speaker 1: does paper and pencil cost? Anyway? Isn't that aren't dose
5:52
Speaker 1: the tools of your research as well? Um? Ten billion
5:56
Speaker 1: dollar particle colliders. You can build those out of pencil
5:59
Speaker 1: and paper. You could, You just haven't tried the paper
6:02
Speaker 1: mache particle collider. Put that on the table next time
6:05
Speaker 1: we're discussing the future of the field. Can you demonstrate
6:07
Speaker 1: mathematically that you cannot build a particle collider with paper mache.
6:11
Speaker 1: Let's show the spitball collider. Yeah, let's see what we
6:13
Speaker 1: can learn my colliding spitballs at nearly the speed of light. Yeah,
6:17
Speaker 1: it's possible, right, it is possible. I have to do
6:19
Speaker 1: some pencil and paper calculations to see what kind of
6:22
Speaker 1: experiments we could do and what we might learn about
6:24
Speaker 1: the universe from a paper machee collider. Yeah, i'll fund
6:27
Speaker 1: out here. Here's five bucks. But this is an interesting question.
6:31
Speaker 1: We're trying to link life on Earth to something as
6:35
Speaker 1: small and maybe and seemingly insignificant as the spin fundamental
6:40
Speaker 1: particle of nature. That's a pretty big leap. It is
6:43
Speaker 1: a pretty big leap, And you might think it sounds
6:45
Speaker 1: a little bit desperate, like is Daniel just trying to
6:47
Speaker 1: be irrelevant to life? But remember that I'm actually doing
6:50
Speaker 1: this research mostly because I think it's irrelevant honestly, because
6:54
Speaker 1: it doesn't affect everyday life on Earth, which means you
6:57
Speaker 1: can't use it to build weapons. Wait, did you just
6:59
Speaker 1: admit your research is irrelevant to all life on Earth.
7:03
Speaker 1: It's irrelevant in the sense that it doesn't have immediate
7:05
Speaker 1: practical applications the way that you admit your research has
7:09
Speaker 1: no immediate practical applications. Oh, absolutely, yes, learning about particles
7:12
Speaker 1: has no immediate practical applications. I can't tell you tomorrow
7:16
Speaker 1: that it's going to improve technology or even next year.
7:19
Speaker 1: It's basic research in the sense that we might discover
7:21
Speaker 1: something crazy and new about the universe. Will down the road,
7:24
Speaker 1: I'm sure will benefit society, but in terms of life
7:27
Speaker 1: immediate impact and you know tomorrow's weapons systems, No, we
7:31
Speaker 1: have no relevance. All right, Well, I guess possible deniabilities
7:34
Speaker 1: is important for some people. But this is an interesting
7:38
Speaker 1: question to wonder if maybe the spin of particles could
7:41
Speaker 1: have affected how life on Earth evolved, or even if
7:43
Speaker 1: life itself evolved at all on this planet. Yeah, it's
7:46
Speaker 1: a fascinating hypothesis with a little bit of evidence to
7:49
Speaker 1: back it up. Well, as usually, we were wondering how
7:51
Speaker 1: many people have thought about this question. I had thought
7:54
Speaker 1: about maybe the properties of particles having an impact on
7:57
Speaker 1: life on Earth, so it's usual Daniel went out there
8:00
Speaker 1: to ask people do you think particle spin can affect
8:03
Speaker 1: life on Earth? So thank you very much to everybody
8:05
Speaker 1: who participates in this segment of the podcast. We really
8:08
Speaker 1: appreciate hearing your thoughts and I think everybody out there
8:11
Speaker 1: enjoys it as well. If you'd like to share your
8:13
Speaker 1: thoughts on the topic of the day for future episodes,
8:16
Speaker 1: please don't be shy right to us. Two questions at
8:19
Speaker 1: Daniel and Jorge dot com. It's what people have to say.
8:22
Speaker 1: I betterly know what particle spin is, but I could
8:27
Speaker 1: surely say that it does not affect life on other
8:30
Speaker 1: planets from the Solar System. Well, everything is spinning. Particles
8:35
Speaker 1: are spinning, the earthy spinning, the galaxy and spinning. Realms
8:41
Speaker 1: are spinning. Everything is spinning. So yeah, the life is spinning.
8:46
Speaker 1: I'm going to say yes, because it affects the way
8:50
Speaker 1: matter is made up. But I really don't know what
8:53
Speaker 1: would happen if particles spin were to be reversed. I
8:56
Speaker 1: don't know for you would even recognize the effects of that.
9:00
Speaker 1: It will be interpreted maybe a couple of ways outside
9:03
Speaker 1: of like the necessity it's spen make physics work, I
9:07
Speaker 1: would say probably not very much impact life. I don't think.
9:10
Speaker 1: I don't think like DNA is interacting with particles spin.
9:14
Speaker 1: All right, Some people said yes, some people said no.
9:17
Speaker 1: There are strong opinions here. There are positive and negative spins.
9:20
Speaker 1: On one hand, it does seem hard to imagine that
9:22
Speaker 1: the behaviors of tiny little particles could affect something like
9:25
Speaker 1: life on Earth. On the other hand, if you believe reductionism,
9:29
Speaker 1: if you believe that everything in the universe comes out
9:32
Speaker 1: of how tiny little bits are dancing around and tooing
9:35
Speaker 1: and frowing that in principle, everything about life comes down
9:38
Speaker 1: to how particles work. Well, yeah, I mean I guess
9:40
Speaker 1: if particles, for example, didn't feel the electromagnetic force, I mean,
9:44
Speaker 1: the whole universe would be different. Yeah, I'm sitting here
9:47
Speaker 1: trying to imagine what a universe would be like without electromagnetism.
9:50
Speaker 1: I mean, it would be a dark universe for sure, right,
9:52
Speaker 1: there would be no light at all in that universe. Yeah.
9:55
Speaker 1: Or I guess even m if the particles had a
9:58
Speaker 1: different mass, it would also change the ole universe, right,
10:01
Speaker 1: like planets would form differently, galaxies would form differently. Who knows,
10:04
Speaker 1: And maybe life can or could have would have formed
10:08
Speaker 1: here on Earth. And yeah, it's a deep mystery why
10:10
Speaker 1: the parameters of the universe seem to be set up
10:13
Speaker 1: to allow life. Although you know, that's just sort of
10:16
Speaker 1: like life that we can imagine. It's possible that if
10:18
Speaker 1: you tweaked all those parameters, you might have completely different chemistry.
10:21
Speaker 1: But that might allow for different kinds of biology, different
10:24
Speaker 1: kinds of life, maybe even different kinds of intelligence. So
10:28
Speaker 1: while the universe does sort of seem fine tuned for us,
10:31
Speaker 1: it might be that other fine tunings are good for
10:34
Speaker 1: other kinds of beings. All right, Well, the question at
10:36
Speaker 1: hand is does particle spin affect life on Earth? And
10:40
Speaker 1: so I guess particle spin is something that is the
10:44
Speaker 1: property of particles. Maybe we can get a little bit
10:46
Speaker 1: into that first. Particle spin is a really fun and
10:49
Speaker 1: super weird property of particles, and it's especially fascinating because
10:54
Speaker 1: the universe seems to have a preference for one kind
10:57
Speaker 1: of spin over another kind of spin. Fundamentally, we don't
11:00
Speaker 1: really know what particle spin is. I mean, you might
11:04
Speaker 1: imagine that it's like a little ball and it's spinning.
11:07
Speaker 1: The problem is that particles are not little balls, and
11:10
Speaker 1: they don't really have surfaces, so we don't think that
11:13
Speaker 1: they are physically spinning. But they do have a property
11:16
Speaker 1: which is very similar to the kind of things we
11:18
Speaker 1: call spin, for like the Earth is spinning and the
11:20
Speaker 1: galaxy is spinning. Particles have properties which have similar mathematical
11:24
Speaker 1: behaviors to spin of like big objects, and so we
11:28
Speaker 1: call it spin even though it's not like technically physically spinning, right,
11:33
Speaker 1: because quantum particles are not like little balls, as you said,
11:36
Speaker 1: they're like little dots basically, and so they have this
11:39
Speaker 1: property called spin. And if it's not related to it
11:42
Speaker 1: actually spinning, why did you call it spin? Or not
11:45
Speaker 1: you specifically, but you know the physics physicism birth did it?
11:48
Speaker 1: Why did they call it spin? They call it spin
11:50
Speaker 1: because even if it isn't actually physically spinning, it is
11:54
Speaker 1: a form of angular momentum. Right, things in the universe
11:57
Speaker 1: can spin, and they can have momentum in the same
12:00
Speaker 1: way that things can have normal momentum. Right, momentum is
12:02
Speaker 1: just like if you push an object, it keeps going,
12:05
Speaker 1: or if you don't push it, it doesn't go anywhere.
12:07
Speaker 1: The same thing holds true for spin. If you spin something,
12:10
Speaker 1: it will keep spinning, like out in space where there
12:12
Speaker 1: isn't any air to slow it down. Or if you
12:14
Speaker 1: don't push an object, it won't spin. Right, It's something
12:17
Speaker 1: floating in space won't spin unless you push it. That's
12:20
Speaker 1: angular momentum, and that's conserved in the universe. That's why
12:22
Speaker 1: if you push something to make it spin, it'll just
12:25
Speaker 1: keep spinning out there in space until something stops it.
12:28
Speaker 1: But you can transfer that angular momentum to something else, right,
12:30
Speaker 1: it can bump into something else and make that spin.
12:32
Speaker 1: We call particles spin spin because it's a kind of
12:36
Speaker 1: angular momentum. You can take anglar momentum and convert it
12:39
Speaker 1: into particle spin and back. So when the universe does
12:42
Speaker 1: its accounting to make sure that angular momentum is conserved,
12:45
Speaker 1: particle spin is part of its balance book, you're allowed
12:49
Speaker 1: to move some angle momentum into that category. So it
12:52
Speaker 1: really is a kind of angular momentum, even if it's
12:55
Speaker 1: a weird quantum kind. But you said that, like regular
12:59
Speaker 1: objects in space and have zero angular momentum or a
13:02
Speaker 1: little bit or a lot of angular momentum, can particles
13:05
Speaker 1: have zero or a lot of angular momentum? And also
13:09
Speaker 1: why not just call it angular momentum? Yes, particles can
13:12
Speaker 1: have different amounts of spin. Of Photons, for example, can
13:15
Speaker 1: have spin up or down or zero. Electrons can only
13:20
Speaker 1: have spin one half or negative one half. They can't
13:22
Speaker 1: have zero spin. They're different kind of particles. So matter
13:26
Speaker 1: particles are all either spin up or spin down by
13:28
Speaker 1: one half, whereas forest particles those can be up or
13:31
Speaker 1: down or zero. Can the same particle have zero and
13:36
Speaker 1: then I give it a spin and then it starts
13:37
Speaker 1: spinning or is it just an inherent property of that
13:40
Speaker 1: particle that's a really interesting philosophy question. Right, Essentially, you're
13:43
Speaker 1: saying a photon moving through the universe with zero spin,
13:47
Speaker 1: if you give it spin, is it's still the same photon. Well,
13:50
Speaker 1: to give it spin, you have to impart angular momentum
13:53
Speaker 1: on it, which means an interaction, and so philosophically it
13:56
Speaker 1: is changed. Right, It's like interacts with some particle, and
14:00
Speaker 1: you think of that as like being absorbed and re emitted.
14:02
Speaker 1: So I think philosophically you can think of it it's
14:05
Speaker 1: like a new particle, or it's at least a new
14:07
Speaker 1: quantum state. But yes, photons can have zero spin, or
14:11
Speaker 1: they can have spin one, or they're gonna have spin
14:13
Speaker 1: minus one m. And the spin it's quantized as well,
14:16
Speaker 1: Like you have a photon with like three point five spin, No,
14:21
Speaker 1: you can't, And you can't have photons with like half
14:23
Speaker 1: a spin or point seven to nine spin. It's absolutely quantized.
14:26
Speaker 1: So photons have three possible states plus one, zero or
14:30
Speaker 1: minus one, and electrons have two states plus a half
14:33
Speaker 1: or minus a half. And that's true for all fer meon's.
14:35
Speaker 1: All fermons are either plus a half or minus a half.
14:38
Speaker 1: They have half integer spins. That's why we call them fermons.
14:41
Speaker 1: They all observe the Firmi exclusion principle, which means they
14:44
Speaker 1: can't be in the same quantum state as each other. Bosons,
14:47
Speaker 1: which have integer spin, they can hang out in the
14:50
Speaker 1: same state, So you can have like a million photons
14:52
Speaker 1: all in the same state. Now, you said earlier that
14:55
Speaker 1: spin is up or down, right, that's kind of the
14:59
Speaker 1: possibility ane's of it. But in a in space there
15:03
Speaker 1: is no up and there's no down. So what does
15:04
Speaker 1: it mean for a spin to be up or down
15:06
Speaker 1: for a particle. Well, in the same way that you
15:08
Speaker 1: can pick any access to calculate ingle momentum, you can
15:11
Speaker 1: pick any access to project the spin. So you have
15:14
Speaker 1: a particle, you pick an access, you say, here's my axis.
15:16
Speaker 1: I want to know if it's spin is up or
15:18
Speaker 1: down along this axis, and you can pick any access
15:21
Speaker 1: you like and call it up or down. Typically, what
15:24
Speaker 1: we do is we choose the axis of the particle's motion,
15:27
Speaker 1: and we ask is the particle spin in the direction
15:30
Speaker 1: of its motion or in the opposite direction of its motion?
15:33
Speaker 1: But isn't. Then then the problem the motion and not
15:36
Speaker 1: the spin. Like if I throw a baseball face up
15:39
Speaker 1: or if I toss a frisbee face up or face down,
15:42
Speaker 1: it's not that it's a whole different frisbee. It's the
15:43
Speaker 1: same frisbee. I just threw it upside down. Yeah. And
15:45
Speaker 1: in the case of particles, you can measure their spin
15:47
Speaker 1: along any direction, or you can measure it along their motion,
15:51
Speaker 1: or you can measure it perpendicular to their motion or
15:53
Speaker 1: in any direction, and you'll always get either plus a
15:56
Speaker 1: half or minus a half or particles. Okay, So it's
15:59
Speaker 1: just some sort of like an arbitrary label. You're saying, like,
16:02
Speaker 1: particles have this thing called spin, and we're gonna there's
16:06
Speaker 1: kind of two kinds of the spin. There's the upspin
16:08
Speaker 1: and there's down spin exactly. And the universe seems to
16:11
Speaker 1: have a preference for particles who spin is pointed away
16:16
Speaker 1: from the direction of their emotion, like an electron is
16:19
Speaker 1: flying through space in the positive ex direction. The universe
16:22
Speaker 1: seems to have a preference for those particles to spin
16:25
Speaker 1: the opposite direction of their motion, for their spin to
16:28
Speaker 1: be sort of like back along the negative X axis.
16:31
Speaker 1: If their motion is in the positive X axis, we
16:34
Speaker 1: call those particles left handed. If their spin is the
16:37
Speaker 1: opposite direction of their motion. I guess it's kind of
16:40
Speaker 1: like a clock. Like a clock can move through space
16:44
Speaker 1: where it's either the face of the clock is facing
16:46
Speaker 1: where it's going, or the face of the clock is
16:49
Speaker 1: facing away from where it's going, or facing back. And
16:51
Speaker 1: so you're saying that particles tend to be the kind
16:54
Speaker 1: where the clock face is facing back. Those kind of
16:57
Speaker 1: particles where the clock is facing backwards with a spin
17:00
Speaker 1: is the opposite direction of motion. We call them left
17:02
Speaker 1: handed particles. In our universe, we have left and right
17:05
Speaker 1: handed versions of most particles, but one of the forces,
17:08
Speaker 1: the weak nuclear force, which is responsible for like beta decay,
17:13
Speaker 1: it will only talk to left handed particles. It does
17:16
Speaker 1: not interact at all with right handed particles. So that's
17:19
Speaker 1: when we mean when we say the universe seems to
17:21
Speaker 1: have a preference for left handed particles. The other forces, electromagnetism,
17:25
Speaker 1: the strong force, they don't care. They're happy to talk
17:28
Speaker 1: to right or left handed particles, but the weak force
17:30
Speaker 1: only talks to left handed particles. So it's almost like
17:34
Speaker 1: the universe um is not ambidexterous, like the universe seems
17:39
Speaker 1: to prefer or at least favor, left handed particles. Over
17:43
Speaker 1: right handed particles. Yeah, and it's a slight preference, right,
17:46
Speaker 1: because remember, the weak force is a feeble force. It
17:49
Speaker 1: is not a powerful force. Does not control the structure
17:52
Speaker 1: of our galaxies, it does not control the structure of
17:54
Speaker 1: your body. It does not control lightning. Right, It's not
17:58
Speaker 1: a very powerful force. And so it's a subtle effect.
18:01
Speaker 1: And this was actually overlooked for years and years and years.
18:04
Speaker 1: Even well after the weak force was discovered, people hadn't
18:07
Speaker 1: really checked to see if it was symmetric, if it
18:10
Speaker 1: talked to both kinds of particles. There was this moment
18:13
Speaker 1: in the middle of last century when people realized, wow,
18:16
Speaker 1: nobody's ever actually checked this to see if the weak
18:19
Speaker 1: force was symmetric. And every thought, of course, it's symmetric.
18:22
Speaker 1: Everything in the universe is symmetric, strong forces, symmetric, electromagnetism
18:26
Speaker 1: is symmetric. It would be bonkers if the weak force
18:29
Speaker 1: was not symmetric. But nobody had checked, and so very
18:32
Speaker 1: quickly a famous scientist at Columbia skipped or Christmas vacation
18:36
Speaker 1: to do this experiment and discover the shocking result that
18:39
Speaker 1: the weak force is not just a little bit anti symmetric,
18:42
Speaker 1: it's completely antisymmetric. It only talks to left handed particles.
18:46
Speaker 1: It was a huge shock wave that went through the
18:48
Speaker 1: physics community about fifty years ago. Yeah, I think we
18:51
Speaker 1: had a whole episode about this experiment that demonstrated the
18:54
Speaker 1: universe has a little bit of a left handed preference,
18:57
Speaker 1: and so this preference has pretty big imp cations and
19:00
Speaker 1: how the universe works and maybe even how life on
19:03
Speaker 1: Earth developed. So let's get into right and left handedness
19:07
Speaker 1: of the universe and life on Earth. But first let's
19:10
Speaker 1: take a quick break. All right, we're asking the question
19:25
Speaker 1: does particle spin affect life on Earth? And so we
19:29
Speaker 1: talked about what spin is. It's a property of particles.
19:32
Speaker 1: Particles can spin up or down. They can be left
19:35
Speaker 1: handed or right handed. And this handedness is something we
19:38
Speaker 1: see all throughout, not just the universe, but nature itself. Right,
19:41
Speaker 1: I mean in Chemis City they talk about hand in
19:43
Speaker 1: this as well of molecules. Yeah, you can apply this
19:46
Speaker 1: principle in general to anything. You can ask if something
19:49
Speaker 1: is left handed or right handed, and basically you're asking
19:53
Speaker 1: would it look the same in the mirror? Right, if
19:56
Speaker 1: you flip something in the mirror, would you get something
19:58
Speaker 1: the same? And You can literally do this experiment in
20:01
Speaker 1: front of yourself with your hands. Like, take your left hand.
20:04
Speaker 1: It's not the same as your right hand right. There's
20:07
Speaker 1: a different orientation of the fingers relative to the thumb.
20:10
Speaker 1: If you put your left hand in the mirror, then
20:12
Speaker 1: it looks like your right hand. Right. The mirror flips
20:15
Speaker 1: your left hand to a right handed sort of shape.
20:18
Speaker 1: But if you just take your right hand, you can't
20:20
Speaker 1: like turn around or twist it in any way to
20:22
Speaker 1: make it look exactly like your left hand. They're different, right.
20:25
Speaker 1: We call that chirality, the one is left handed and
20:28
Speaker 1: one is right handed, that they're not the same, right.
20:30
Speaker 1: I guess if you're doing the mirror experiment, you would
20:33
Speaker 1: see that maybe some parts in your body are symmetric
20:36
Speaker 1: and are are not handed right. Like if you take,
20:39
Speaker 1: for example, your eyeball, if you put it in front
20:41
Speaker 1: of the mirror, you can't tell which eyeball it is,
20:44
Speaker 1: where your right one or your left one right, the
20:46
Speaker 1: one eyeball looks the same in the mirror as in
20:49
Speaker 1: as it does in you. Or for example, I think
20:51
Speaker 1: your your nose right, Your nose is also a symmetric
20:54
Speaker 1: You can't sort of tell which one is the mirror
20:56
Speaker 1: one which is the real nose. But like your right hand,
20:58
Speaker 1: you can't tell which one is, assuming a spherical eyeball.
21:01
Speaker 1: I think that's true, and my nose actually isn't symmetric.
21:04
Speaker 1: I could tell the difference in the mirror because it
21:07
Speaker 1: leans one way instead of the other. That can be fixed. Right,
21:11
Speaker 1: we are in Orange County. I mean basically, everybody's getting
21:13
Speaker 1: some work done these days. In principle and idealized human nose,
21:16
Speaker 1: you're right, is symmetric, and yeah, hands are not symmetric. Right,
21:20
Speaker 1: the real life version of your left hand looks like
21:22
Speaker 1: a right hand in the mirror. Right, And the same
21:25
Speaker 1: can be said about molecules, right, Like, you can arrange
21:27
Speaker 1: a molecule in a way that is symmetric, where it
21:30
Speaker 1: looks the same in the mirror, or you can arrange
21:32
Speaker 1: a molecule in a way that does not look the
21:34
Speaker 1: same in the mirror. An example of a symmetric molecule
21:37
Speaker 1: is like water. Right, water is H two. Oh, you
21:40
Speaker 1: have two hydrogens with an oxygen in the middle. If
21:43
Speaker 1: you flip it, like if you make the left side
21:45
Speaker 1: the right side and vice versa, it looks the same right,
21:47
Speaker 1: it's exactly the same in the mirror, but you can
21:49
Speaker 1: build much more complicated molecules, and chemistry of life specifically
21:54
Speaker 1: is filled with complex molecules built off of these carbon chains,
21:58
Speaker 1: and those do have a chirality. They do not look
22:01
Speaker 1: the same in the mirror. There are left handed versions
22:04
Speaker 1: and right handed versions basically every kind of molecule. So
22:08
Speaker 1: if you just say the chemical formula c H four
22:11
Speaker 1: for example, that tells you what's in it. It doesn't
22:14
Speaker 1: tell you which orientation is it is. It's the left
22:17
Speaker 1: handed or the right handed version of that object. Right,
22:20
Speaker 1: Like c H four you can take one carbon and
22:22
Speaker 1: four hydrogen and put them in together in one way
22:26
Speaker 1: or in a way that looks like it's mirror image.
22:28
Speaker 1: That's what do you mean? Right? Actually, c H four
22:30
Speaker 1: is an example of a molecular probably is symmetric. You
22:33
Speaker 1: have the carbon and then the hydrogens are arranged around it.
22:36
Speaker 1: So I think it does look symmetric in the mirror.
22:37
Speaker 1: But as they get more complicated, you know, for example,
22:40
Speaker 1: the meno acids and the building blocks of life, these
22:42
Speaker 1: are much more complicated structures. They're not all the same
22:45
Speaker 1: in the mirror. Yeah, Like if you take carbon a
22:47
Speaker 1: bunch of carbon and a bunch of hydrogen and some
22:50
Speaker 1: other atoms. There are two different ways you could maybe
22:52
Speaker 1: put them together. You could put them together in one
22:54
Speaker 1: way or in a way that looks like it's mirror image,
22:57
Speaker 1: which is not the same. Molecular just looks the same
23:00
Speaker 1: in the mirror, and it actually kind of affects how
23:02
Speaker 1: it interacts with other molecules. Right, Like a right handed
23:05
Speaker 1: molecules doesn't do the same things as a left handed molecule. Yeah, Interestingly,
23:10
Speaker 1: you can't just mix them. You can't have a bunch
23:13
Speaker 1: of left handed molecules and a bunch of right handed
23:15
Speaker 1: molecules and assume that they will all act the same.
23:18
Speaker 1: Because chemistry is like these little building blocks. He's like
23:21
Speaker 1: tiny little machines made out of proteins. They have to
23:24
Speaker 1: click together and just the right way to like activate
23:27
Speaker 1: certain sites to cleave off bits of a molecule. It's
23:29
Speaker 1: actually trying to shake somebody's hand but using the wrong
23:31
Speaker 1: hand it just doesn't sort of fit together, or trying
23:34
Speaker 1: to dance where both people are leading. In order for
23:37
Speaker 1: the chemistry of life to happen, everything has to match.
23:40
Speaker 1: Means you need like all the pieces to have the
23:42
Speaker 1: right chirality, so you can't mix and match left and
23:45
Speaker 1: right handed chemistry of life. That's why I fastpoint people
23:49
Speaker 1: when I meet them these days. It's just too confusing.
23:51
Speaker 1: But I was thinking, it's sort of like Tetris, right,
23:53
Speaker 1: Like in Tetris, you have pieces, and like every piece
23:56
Speaker 1: in Tetris is made out of four blocks, but depending
23:58
Speaker 1: on how you put them there is symmetrical or not.
24:00
Speaker 1: Like if you have a two white two block, that's
24:02
Speaker 1: a metric and you can slide that in anywhere. But
24:04
Speaker 1: if you have like an L shaped block, then you
24:06
Speaker 1: gotta wait for the right left hand or the right
24:09
Speaker 1: side L block to fit a certain spot in your
24:12
Speaker 1: touchris pile. And for the chemistry of life to work,
24:15
Speaker 1: it seems like you need to be either all one
24:17
Speaker 1: chirality or all the opposite chirality. And that's exactly what
24:20
Speaker 1: we see when you take organic molecules and you sort
24:23
Speaker 1: of like distill them from living objects, from plants or whatever,
24:26
Speaker 1: you see all one chirality. All of life on Earth
24:30
Speaker 1: uses left handed amino acids and right handed sugars. There's
24:34
Speaker 1: nothing alive on Earth that uses right handed amino acids
24:38
Speaker 1: or left handed sugars that form of life just does
24:41
Speaker 1: not exist, right, But it's it's like, it's possible to
24:44
Speaker 1: make right handed amino acids, but all life on Earth
24:47
Speaker 1: seems to use only left handed amino acids. And once
24:50
Speaker 1: life got started and life starts to make amino acid,
24:53
Speaker 1: it then only makes left kind, which is the kind
24:56
Speaker 1: of uses. If you synthesize some organic molecular like to
25:00
Speaker 1: make one of the amino acids chemically from basic building blocks,
25:04
Speaker 1: you'll end up with both kinds, left handed and right handed.
25:07
Speaker 1: But if you pull it out of life, if you
25:09
Speaker 1: distill it from a living being, you'll only get one chirality, right,
25:13
Speaker 1: and you're right. We think that life is possible with
25:16
Speaker 1: the other orientation. We suspect that it is, though of
25:19
Speaker 1: course we don't have any examples. We think the probably
25:22
Speaker 1: universe is symmetric and that it would allow for life
25:25
Speaker 1: to have both chiralities, but we don't actually know. Well,
25:28
Speaker 1: that's interesting to think about, Like maybe there's a version
25:32
Speaker 1: of humans out there, maybe the multiverse or maybe in
25:35
Speaker 1: this universe that uses only right handed amino acids, and
25:39
Speaker 1: maybe if we met them, I mean, we could shake hands,
25:41
Speaker 1: but we couldn't. Maybe like have kids together, right, or
25:44
Speaker 1: even eat their food, because our bodies cannot interact with
25:47
Speaker 1: that kind of chemistry. I mean, like some of the
25:50
Speaker 1: artificial sweeteners that are in our foods are really interesting
25:53
Speaker 1: because they exploit the fact that, despite being a sugar
25:56
Speaker 1: and they do interact with your tongue in a way
25:59
Speaker 1: that you can haste them, our bodies can't actually take
26:02
Speaker 1: them apart to use energy, so we can't metabolize them
26:06
Speaker 1: even though we can taste them because they have the
26:08
Speaker 1: wrong chirality. Interesting, Yeah, artificial sweet nurse you're saying, used
26:13
Speaker 1: the wrong candidness of sugar molecules which activate our taste buds,
26:17
Speaker 1: but they can't be processing our stomachs, yeah, because those
26:21
Speaker 1: are different processes, right, Tasting something recognizing the sugar your
26:25
Speaker 1: tongue doesn't actually break it down and extract the energy,
26:28
Speaker 1: and so it's like, oh, yeah, that's sugar plus one
26:30
Speaker 1: for you. But then when he gets into your stomach,
26:32
Speaker 1: the little machines down there that take things apart and
26:34
Speaker 1: actually extract the energy and turn it into a TP
26:37
Speaker 1: they're like, I don't know what to do here. My
26:39
Speaker 1: locks are not fitting into these keys. So it just passes, right,
26:41
Speaker 1: through you. Mmm. Interesting, this is something we've known for
26:45
Speaker 1: a while, right. This was discovered by Louis Pasteur himself
26:48
Speaker 1: more than a hundred and fifty years ago. He synthesized
26:51
Speaker 1: a bunch of chemicals and then he also distilled them
26:54
Speaker 1: from life, and he noticed this difference. He noticed that
26:57
Speaker 1: the ones that came from life had only one chirality,
27:00
Speaker 1: and the ones that he synthesized himself had both kinds
27:03
Speaker 1: of chirality. So it's been an open puzzle for more
27:06
Speaker 1: than a hundred fifty years of why life has this thing.
27:09
Speaker 1: They call it bio chirality. But back then, how do
27:12
Speaker 1: we know that a molecule was right handed or left handed? Right?
27:15
Speaker 1: We can like X ray it or have super electron microscopes.
27:19
Speaker 1: The way he discovered it was that these chiralities interact
27:22
Speaker 1: with light a little bit differently. The light can have
27:24
Speaker 1: different polarizations, which is related to the spin of those photons,
27:28
Speaker 1: and that interacts slightly differently with those photons. And so
27:31
Speaker 1: that's how he detected that the chemicals that he pulled
27:34
Speaker 1: out of life were different from the chemicals that he
27:37
Speaker 1: synthesized in the laboratory. And he actually predicted before we
27:41
Speaker 1: even knew about the weak force or parody violation. He
27:44
Speaker 1: predicted that there must be some sort of cosmic particle
27:47
Speaker 1: asymmetry which is generating this fundamental asymmetry in life. So
27:52
Speaker 1: like a hundred years before we discovered parody violation, he
27:55
Speaker 1: basically predicted it. Wait one, he was thinking, maybe the
27:59
Speaker 1: reason of life and Earth is mostly left handed. One
28:03
Speaker 1: type of molecule is something like something from space. He
28:07
Speaker 1: was thinking that this asymmetry was revealing a deep asymmetry
28:11
Speaker 1: in the universe itself. Right, there must be some sort
28:14
Speaker 1: of cosmic origin to this. So pastor a road. This
28:17
Speaker 1: is in eighteen forties Hero quote. If the foundations of
28:21
Speaker 1: life are die symmetric, then because of die symmetric cosmic
28:26
Speaker 1: forces operating at their origin. This, I think is one
28:29
Speaker 1: of the links between life on the Earth and the cosmos.
28:33
Speaker 1: That is the totality of forces in the universe. So
28:36
Speaker 1: that's Pasteur writing in the eighteen hundreds, before we understood
28:39
Speaker 1: life the quantum nature of these forces or particle spin
28:42
Speaker 1: or parody violation at all, he had the sense that
28:45
Speaker 1: maybe the handedness of life came somehow from the handedness
28:49
Speaker 1: of the universe. Whoa feels like a little bit of
28:52
Speaker 1: a stretch there for Li to make that connection. It
28:57
Speaker 1: might be one of these things where people write a
28:59
Speaker 1: lot and most of their predictions are wrong, but when
29:02
Speaker 1: they do hit the jackpot, people later on dig them
29:05
Speaker 1: out and like, hey, look how forward thinking they are,
29:08
Speaker 1: you know, the way you can find almost anything you like.
29:10
Speaker 1: In the writings of mister Damis, I wonder if it's
29:12
Speaker 1: sort of like saying like, maybe in a way he
29:14
Speaker 1: would saying I mean, I'm sure no, he was assignist,
29:16
Speaker 1: but maybe in a way he's saying like, you know,
29:18
Speaker 1: maybe God is left handed and that's why he made
29:20
Speaker 1: a human, you know, humans in a particular handed or
29:24
Speaker 1: like maybe God is right handed, that's why most humans
29:26
Speaker 1: are right hand Yeah, that's another great example of asymmetry. Right,
29:30
Speaker 1: why are humans mostly right handed and not left handed?
29:34
Speaker 1: We know that it can work both ways, obviously, but
29:36
Speaker 1: why are humans mostly right handed and not mostly left handed?
29:40
Speaker 1: It seems like sort of an arbitrary choice, and it
29:42
Speaker 1: makes you wonder, like where does that come from? Is
29:44
Speaker 1: it just random or is there a fundamental reason at
29:47
Speaker 1: the heart of the universe that's creating this asymmetry that's
29:51
Speaker 1: sort of the philosophy question, right, you always want to
29:53
Speaker 1: know the why, not just the how, right, right, And
29:56
Speaker 1: we all know we're just here to set things up
29:58
Speaker 1: for the greater discipline of philosophy. But I think, you know,
30:01
Speaker 1: if I guess, if half of the humans on Earth
30:03
Speaker 1: are right handed and half of them were left handed,
30:05
Speaker 1: it would be pretty awkward all the time trying to
30:08
Speaker 1: shake hands with people. So maybe the whole reason most
30:12
Speaker 1: people right hand is just to you know, make things
30:14
Speaker 1: more social. Yeah, I think that's beyond my pay grade.
30:17
Speaker 1: All right, Well, that's a big question. Why does life
30:19
Speaker 1: on Earth prefer one kind of handed molecules and not
30:24
Speaker 1: the other? I guess one reason is that it could
30:26
Speaker 1: have been random, right, Like it just you know, picked
30:29
Speaker 1: the left handed molecules and went with that. Yeah, it
30:33
Speaker 1: could be basically a coin flip billions of years ago.
30:37
Speaker 1: It could have gone either direction. But once you pick
30:40
Speaker 1: one side, it's like symmetry breaking. Then you just gotta
30:43
Speaker 1: go with it. Like if a bunch of people are
30:45
Speaker 1: seated at a table and you have like glasses placed
30:48
Speaker 1: between the plates, is your glass on the left side
30:51
Speaker 1: or the right side? As soon as one person picks
30:53
Speaker 1: their glass on the right side, then everybody's going to
30:55
Speaker 1: use the right handed glass. But they could have picked
30:57
Speaker 1: the left one and everything would have worked just fine.
31:00
Speaker 1: So we don't know if it was just like a
31:02
Speaker 1: random event billions of years ago in the primordial soup
31:06
Speaker 1: that led us to all have this one handedness, or
31:09
Speaker 1: maybe there is a reason. Yeah, I wonder like if
31:12
Speaker 1: there was some competition in the early life billions of
31:15
Speaker 1: years ago, like maybe a bunch of particles started assembling
31:19
Speaker 1: with the left handed way and a bunch of particles
31:21
Speaker 1: started assembling in a right handed way, and for a while,
31:24
Speaker 1: maybe there was life could potentially early on there could
31:28
Speaker 1: have been life with both handedness. It's just that one
31:30
Speaker 1: somehow beat out the other. Yeah, it could be, or
31:33
Speaker 1: it could be that it's selected for either before life
31:36
Speaker 1: starts or after. Right, it might be that the processes
31:39
Speaker 1: that generate these organic molecules naturally prefer to generate them
31:44
Speaker 1: in a right handed or left handed way, like out
31:46
Speaker 1: there in space when you have these organic molecules in soups,
31:50
Speaker 1: are there equal amounts of left and right handed molecules?
31:53
Speaker 1: Or is there an asymmetry there before life even gets started?
31:56
Speaker 1: And then you can also ask afterwards, if life gets
31:59
Speaker 1: started equal leave often left and right handed, is there
32:02
Speaker 1: some preference for is one more likely to survive? Is
32:06
Speaker 1: there something about the universe which gives one of them
32:09
Speaker 1: a boost? Right? I think you're asking, maybe God is
32:11
Speaker 1: not ambidexterous. Maybe God this my preference for right or
32:16
Speaker 1: left handed? And could we see that in the laws
32:18
Speaker 1: of the universe. And so let's get into whether or
32:21
Speaker 1: not there is a connection between the left handedness of
32:24
Speaker 1: life and the right handedness of quantum particles. But first
32:28
Speaker 1: let's take another quick break. All right, we are doing
32:43
Speaker 1: some of the pre work here for philosophers or warming
32:48
Speaker 1: the crowd up here with some interesting thinking about the
32:52
Speaker 1: universe and life on Earth, asking the question can particles
32:55
Speaker 1: spin or did particles spin affect life on Earth? And
32:58
Speaker 1: so we've talked about how fundamental quantum particles have a spin,
33:02
Speaker 1: they have an upper down spin. And we also talked
33:05
Speaker 1: about how life on Earth has a preference for left
33:07
Speaker 1: handed molecules over right handed amino acid molecules. And so
33:11
Speaker 1: the question is are these two things related. Does the
33:14
Speaker 1: spin of sparticles of fact how molecules form or do
33:18
Speaker 1: somehow the laws of physics somehow prefer left handed amino acids.
33:22
Speaker 1: Let's get into that connection. It is a really fun question.
33:25
Speaker 1: And I was reading this very long and detailed paper
33:28
Speaker 1: about the connections between particle spin and bio chirality and
33:31
Speaker 1: actually start out with a bit of a rant, a
33:33
Speaker 1: complaint about calling life left handed or right handed, because
33:36
Speaker 1: there's all sorts of ways you can define it. So
33:38
Speaker 1: they prefer to define the orientation of our chemistry as
33:42
Speaker 1: live l i v E and the opposite orientation as
33:46
Speaker 1: evil live backwards e v I L. So this whole
33:50
Speaker 1: paper talks about normal life versus evil life. And this
33:53
Speaker 1: is a physics paper or is this a blog post?
33:58
Speaker 1: This is a science paper published in the Prestigious journal.
34:01
Speaker 1: And somehow calling life evil or live is better than
34:04
Speaker 1: calling it the left handed or right handed. I don't know.
34:07
Speaker 1: It's a philosophy question. So this is all based kind
34:10
Speaker 1: of on on a paper that tries to make connection
34:12
Speaker 1: between quantum particle spin and the kind of the corality
34:15
Speaker 1: or the handedness of life molecules. Is there a connection
34:18
Speaker 1: danial between these two things. So there is a plausible
34:20
Speaker 1: mechanism for connecting the preference of the weak force to
34:25
Speaker 1: produce left handed particles and life selecting for this kind
34:31
Speaker 1: of chirality. There's a plausible mechanism. It's very very thin,
34:35
Speaker 1: it's a very very slight preference, and it's not something
34:37
Speaker 1: we've proven, but it is possible, and it comes down
34:41
Speaker 1: to particles from space. Right. Cosmic rays are these particles
34:45
Speaker 1: that hit the Earth at very very high speeds and
34:48
Speaker 1: they come from like the centers of other galaxies, or
34:51
Speaker 1: they come from our Sun, and they're just normal particles, protons, electrons, positrons.
34:57
Speaker 1: Sometimes they hit the top of the atmosphere and they
34:59
Speaker 1: create big shower of particles. Because a particle hits the
35:02
Speaker 1: atmosphere is sort of like a meteor hitting the atmosphere.
35:05
Speaker 1: It heats up and slows down and spreads out its energy,
35:08
Speaker 1: so you get a big shower of particles on the surface.
35:11
Speaker 1: And this is something very normal. It's something we've been
35:13
Speaker 1: experiencing as living beings on the surface of the Earth
35:16
Speaker 1: for a very very long time. Cosmic rates hit the
35:18
Speaker 1: atmosphere and create essentially radiation on the surface of the
35:22
Speaker 1: Earth that interacts with us and interacts with our organic chemistry,
35:26
Speaker 1: specifically our d n A. Right. We sort of can't
35:29
Speaker 1: see it on our on our regular skies, but you
35:32
Speaker 1: can sort of see it in the northern lights, right.
35:33
Speaker 1: That's kind of what the northern lights are. Particles hitting
35:36
Speaker 1: the atmosphere. Yeah, Particles hitting the atmosphere and in that
35:39
Speaker 1: case getting shunted up to the poles by the magnetic fields.
35:42
Speaker 1: One of the reason that we don't have more radiation
35:44
Speaker 1: here on the surface of the Earth is our atmosphere.
35:46
Speaker 1: The second reason is our magnetic field acts sort of
35:49
Speaker 1: like a shield, but some of it does get through
35:52
Speaker 1: and gets down to the surface and affects the way
35:54
Speaker 1: life operates. You know. A crucial element of evolution is mutation. Right.
35:59
Speaker 1: You don't want just to copy the genes of the parents.
36:02
Speaker 1: You want to try something new, which requires either making
36:05
Speaker 1: a mistake when you're transcribing the DNA from the parent
36:08
Speaker 1: to the child, or having a mistake introduced from for example,
36:12
Speaker 1: a cosmic ray. A mu on passing through your DNA,
36:15
Speaker 1: for example, could alter the chemistry of it in the
36:18
Speaker 1: same way that like radiation can give you cancer by
36:21
Speaker 1: changing the fundamental operation of your cells, it can also
36:24
Speaker 1: change your d NA. Yeah, and that's kind of an
36:27
Speaker 1: essential ingredient in life and evolution, right, Like if you
36:31
Speaker 1: didn't have mutations, then life would never evolve, It would
36:34
Speaker 1: never change, like that's how it started. But also like,
36:37
Speaker 1: you need mutations just to evolve life because the DNA
36:40
Speaker 1: never changed. If it copied perfectly from one generation to
36:43
Speaker 1: the other, you would just still have the same organism
36:46
Speaker 1: you started with. You would never evolve or come up
36:48
Speaker 1: with better versions of the species. Yeah, in order to
36:51
Speaker 1: explore the space of all possible organisms effectively, right, you
36:56
Speaker 1: need a population that has different abilities, and the best
36:59
Speaker 1: way to do that is to introduce random mutation. That's
37:02
Speaker 1: essentially what evolution does. So cosmic rays have played an
37:05
Speaker 1: important part in our evolution. We think it's actually key.
37:08
Speaker 1: Like if you could build a perfect shield so we
37:10
Speaker 1: had no radiation on the surface of the Earth, then
37:12
Speaker 1: the history of life on Earth would be very very different.
37:15
Speaker 1: It might not have succeeded. Right, Well, you would still
37:17
Speaker 1: have mutations, did you just wouldn't have them from radiation
37:21
Speaker 1: coming from space. Right, And we don't really know what
37:24
Speaker 1: would happen in that scenario, right, life would evolve very differently.
37:27
Speaker 1: Changes the conditions of life, And so what we do
37:30
Speaker 1: know is that the conditions we have here on Earth
37:32
Speaker 1: are the ones that gave birth to us, right to
37:34
Speaker 1: this kind of life, Right, I guess, I guess if
37:37
Speaker 1: we had less of a shielding from radiations from space,
37:40
Speaker 1: we would have had more radiation and maybe too many mutations, right,
37:43
Speaker 1: in which case we wouldn't have evolved either. Yeah, it's
37:46
Speaker 1: really interesting question is sort of like bio philosophy, like
37:49
Speaker 1: what is the best rate of mutation? We just don't
37:51
Speaker 1: know the answer to that. People theorize and run experiments.
37:54
Speaker 1: But you know, we have a certain level of radiation
37:56
Speaker 1: and we think that that's a key part of how
37:57
Speaker 1: we evolved to be who we are. Right, So, then
38:00
Speaker 1: how does left the right handedness come into it? Well,
38:02
Speaker 1: it turns out that these cosmic rays that come from
38:05
Speaker 1: space are not equally left or right handed. When we
38:09
Speaker 1: talk about the particle spin, is what happens when a
38:11
Speaker 1: particle hits the upper atmosphere is it creates the shower
38:14
Speaker 1: of particles. Typically, these particles called pions, which don't live
38:18
Speaker 1: very long. They tend to decay, and they decay into muans.
38:22
Speaker 1: That decay is done by the weak force. The weak
38:25
Speaker 1: forces the thing that breaks up the pions, It turns
38:27
Speaker 1: it into a muon and also for example, a new trino,
38:31
Speaker 1: and because the weak forces in charge of that moment,
38:33
Speaker 1: it only makes left handed muans because that's all it
38:36
Speaker 1: knows how to do. It doesn't know how to make
38:37
Speaker 1: right handed muans. It ignores right handed muans. It pretends
38:40
Speaker 1: they don't even exist. So, coming from space, were overwhelmed
38:44
Speaker 1: with left handed muans, which means that the cosmic rays,
38:48
Speaker 1: all of a sudden, are not symmetric. Right, so the
38:50
Speaker 1: environment we've involved in is not symmetric because of the
38:54
Speaker 1: weak force, and those left handed muans tend to interact
38:58
Speaker 1: with our d NA slightly differently than right handed muans would,
39:02
Speaker 1: meaning that most of the meals that come down on
39:04
Speaker 1: Earth are left handed, not right handed exactly. Those muons
39:08
Speaker 1: are left handed, and that creates a slight preference for
39:11
Speaker 1: left handed amino acids. We think that left handed muons
39:15
Speaker 1: have a slightly higher probability of ionizing left handed amino
39:20
Speaker 1: acids than right handed amino acids. Wait, what, why why
39:24
Speaker 1: is it that left handed muons interact mostly with left
39:27
Speaker 1: handed amino acids. It's very subtle effect, but it's again
39:30
Speaker 1: because of the weak force. The weak force has this
39:33
Speaker 1: asymmetry and has very small effects on the chemistry of life.
39:37
Speaker 1: It can, for example, change the electric and magnetic dipole
39:41
Speaker 1: moments of some of these atoms inside these molecules, so
39:45
Speaker 1: their shape is like slightly different if they're left handed
39:47
Speaker 1: or right handed, which means that the muons passing through
39:50
Speaker 1: them are like more or less likely to interact with
39:53
Speaker 1: them because they spend like more or less time within
39:56
Speaker 1: that electric or magnetic atomic fields. It's a very subtle
39:59
Speaker 1: calculat Wait, are you saying that the left handed muons
40:02
Speaker 1: showering the Earth, coming down on earth thrower atmosphere are
40:05
Speaker 1: more likely to interact with a certain type of atom
40:10
Speaker 1: or a certain type of electron that you can only
40:13
Speaker 1: see on the left handed molecules. Yeah, that's right. Left
40:16
Speaker 1: handed muans will interact with right handed or left handed
40:20
Speaker 1: amino acids, but they are more likely to interact with
40:23
Speaker 1: left handed amino acids than right handed just by a
40:25
Speaker 1: little bit. It's not like a complete preference. Why because there,
40:29
Speaker 1: like a left handed amino acid is different than the
40:31
Speaker 1: right hand aminu acid, not because of any spin, it's
40:33
Speaker 1: just how the particles atoms are arranged. So why would
40:37
Speaker 1: the left handed muan, which is a tiny tiny particle
40:40
Speaker 1: care about the giant structure of a molecule, because when
40:43
Speaker 1: the muon is interacting with that atom, it's interacting not
40:47
Speaker 1: just with the electromagnetic force, but also with the weak force,
40:50
Speaker 1: because the mulan feels the weak force. And so there
40:52
Speaker 1: is a difference between the left and right handed amino
40:55
Speaker 1: acids because of the weak force affects the electric dipole
40:59
Speaker 1: moment in the mag netic dipole moments of these atoms,
41:03
Speaker 1: and so that affects how the left or right handed
41:05
Speaker 1: particles will interact with them. Are you saying that like
41:08
Speaker 1: a left handed amino acid is made up of different
41:11
Speaker 1: atoms or different atoms with different spins than the right
41:14
Speaker 1: handed amino acid. No, it's the same atoms, right, it's
41:17
Speaker 1: just flipped to be left handed, and so the arrangement
41:20
Speaker 1: is slightly different, and that gives a different pattern of
41:23
Speaker 1: the electromagnetic fields. And this is a very small effect, right,
41:27
Speaker 1: This is really a tiny effect. It's like second order.
41:30
Speaker 1: This effect is like three parts in twenty thousand. Right,
41:33
Speaker 1: most of the time these things will be treated exactly
41:36
Speaker 1: the same, because most of the time is the electromagnetic
41:39
Speaker 1: interaction that dominates, which is symmetric, but the weak force
41:42
Speaker 1: sometimes it is a thing that mediates at interaction, and
41:45
Speaker 1: so it tends to prefer the left handed version of
41:47
Speaker 1: these amino acids. But again just a tiny fraction of
41:50
Speaker 1: the time. Oh, it seems to be like a totally
41:53
Speaker 1: different effect, like a left handed muon. It could have
41:55
Speaker 1: been that the left handed muon prefers to interact with
41:58
Speaker 1: the right handed molecule. Right, It's just that it just
42:02
Speaker 1: so happens that the molecules that left handed meals like
42:05
Speaker 1: to interact with a little bit more are the ones
42:08
Speaker 1: we call the left handed amino acids. Yeah, that's right.
42:11
Speaker 1: Or in this paper they call them the live choice.
42:14
Speaker 1: And the paper they go through this very complicated calculation
42:18
Speaker 1: and they come out with this prediction. They say, we
42:20
Speaker 1: predict that there is a difference and it has to
42:22
Speaker 1: do with the time the particle spends traversing the electromagnetic
42:25
Speaker 1: field and how the weak force interacts with it, and
42:28
Speaker 1: so they predict this very slight effect. Again, really really
42:32
Speaker 1: tiny effect. But the idea is that maybe over millions
42:35
Speaker 1: and billions of years, these cosmic rays introduced more ionization
42:40
Speaker 1: effects in our kind of chirality and not in the
42:44
Speaker 1: evil the alternative kind of bio chirality which give us
42:48
Speaker 1: a boost, which let us explore these things faster, create
42:51
Speaker 1: more mutations and sort of like adapt more rapidly to
42:55
Speaker 1: changing conditions, And that maybe over billions of years, lad
42:59
Speaker 1: life to have this chirality instead of the opposite hiality
43:02
Speaker 1: because we get more mutations from left handed cosmic rays.
43:07
Speaker 1: I see. I think it's all making sense now because
43:08
Speaker 1: there are many different kinds of amino acids right like,
43:11
Speaker 1: I think maybe what this writer is saying is that
43:13
Speaker 1: there's lots of different kinds of amino acids, but the
43:17
Speaker 1: ones that are used by life right now, he wants
43:19
Speaker 1: to call those like A and the one. The versions
43:23
Speaker 1: that are not used by us, he wants to call
43:26
Speaker 1: those B and so he wants he's trying to say,
43:29
Speaker 1: or she's trying to say that left handed muons, can
43:33
Speaker 1: you can prove that maybe that left handed muans somehow
43:36
Speaker 1: like to interact more with a kinds of amino acids
43:39
Speaker 1: than be kind of amino acids. They're saying that he's
43:42
Speaker 1: saying left and right for the muons and left and
43:45
Speaker 1: right for the molecules is confusing. Let's just call them
43:48
Speaker 1: molecules A or B, A being the ones that life
43:50
Speaker 1: prefers seems to have preferred here on Earth. And then
43:53
Speaker 1: let's take the left and right hand for the Muans,
43:55
Speaker 1: where in the article they call A live and be evil.
43:58
Speaker 1: But yeah, we can go with A versus B. Yeah,
44:00
Speaker 1: it sounds a little more benign. I mean, if we
44:02
Speaker 1: do meet like humans from another place and they have
44:04
Speaker 1: the other handedness of their biochyrality, you're not gonna let
44:08
Speaker 1: me call them evil humans? No, because how do you
44:11
Speaker 1: know you're not the evil one? Maybe left handed humans
44:14
Speaker 1: are better than right hand humans. I think I've just
44:17
Speaker 1: realized we are the badis, aren't we? That's right? The
44:19
Speaker 1: enemy is us. We've met the enemy and it is us, Yes, exactly.
44:25
Speaker 1: So that's the idea. And nobody knows if this effect
44:28
Speaker 1: is big enough to actually have an impact on life
44:31
Speaker 1: at all. There's a lot of dot dot dots here.
44:34
Speaker 1: It's like almost the same as pasteurs saying like maybe
44:37
Speaker 1: somehow the universe prefers one kind of chirality. This is
44:40
Speaker 1: the way that the universe does seem to prefer one
44:43
Speaker 1: side of a symmetric pair, and you can draw some
44:46
Speaker 1: dots between that and how it might have influenced life.
44:49
Speaker 1: It's not conclusive to say that this is definitely why
44:52
Speaker 1: life has this reality, but maybe the the idea here
44:56
Speaker 1: is that the kinds of I mean, assets that flourished
44:58
Speaker 1: here on Earth flourished because they're more likely to be
45:02
Speaker 1: affected by left handed new muans, which is what the
45:05
Speaker 1: universe prefers to make. And so it's in a way,
45:07
Speaker 1: the universe kind of preferred to make the a kind
45:10
Speaker 1: of amino acid or the one the kind that lead
45:13
Speaker 1: to us, at least here on Earth. You know, in
45:15
Speaker 1: our Solar system, Earth is the only planet that has
45:18
Speaker 1: an atmosphere, which creates these muon showers that come all
45:22
Speaker 1: the way down to the Earth's surface. Muans don't last
45:24
Speaker 1: very long. They last form micro seconds, but because they're
45:28
Speaker 1: going so fast, they actually do penetrate down to the
45:31
Speaker 1: Earth because their clocks are time dilated due to special relativity,
45:34
Speaker 1: so they tend to die off right around the Earth's surface.
45:37
Speaker 1: If the Earth's atmosphere was thicker, for example, they would
45:40
Speaker 1: make it all the way down to the ground. Right,
45:41
Speaker 1: But that's just our solar system. This preference for left
45:44
Speaker 1: handed muons is universal, right, It's a basically a lot
45:48
Speaker 1: of the universe. And so if there are other planets
45:51
Speaker 1: like ours with an atmosphere, and if maybe the very
45:54
Speaker 1: existence of life depends on having that kind of atmosphere
45:58
Speaker 1: in that planet, the condition may also prefer the A
46:02
Speaker 1: kind of amino acid that we're made out of, because
46:05
Speaker 1: the universe is prefers left handed muance and so over there,
46:08
Speaker 1: also the universe will prefer the A kind of amino acid. Yeah,
46:12
Speaker 1: that's the hypothesis right, not yet proven, but that's the
46:15
Speaker 1: idea that maybe this is the reason that we have
46:18
Speaker 1: the A kind of amino acid and not the B kind.
46:21
Speaker 1: So you're saying we're less likely to meet evil twin
46:25
Speaker 1: versions of us out there, were more likely to meet
46:28
Speaker 1: people who are just like us. Yeah, maybe particle spin
46:31
Speaker 1: will make for happy reunions with aliens. Yes, with non
46:34
Speaker 1: awkward hand shaps. Maybe we should just fist bump the
46:37
Speaker 1: aliens when they get here, just in case. Yeah, that
46:39
Speaker 1: always works. I'm up for that that way, Well, you
46:42
Speaker 1: don't have to have that awkward question when you meet
46:44
Speaker 1: an alien. Hey are you right handed or left handed? Uh?
46:47
Speaker 1: Fist bump? All right. Well, that's an interesting idea that
46:50
Speaker 1: maybe the universe does have a preference for the kind
46:53
Speaker 1: of life that we're made out of, and that we
46:56
Speaker 1: were maybe destined to be the way we are right now,
46:58
Speaker 1: and maybe Particles six is actually relevant to our life
47:02
Speaker 1: and your life and all life in the universe. We
47:05
Speaker 1: hope you enjoyed that. Thanks for joining us, see you
47:07
Speaker 1: next time. Thanks for listening, and remember that Daniel and
47:18
Speaker 1: Jorge explained. The Universe is a production of I Heart Radio.
47:21
Speaker 1: For more podcast for my heart Radio, visit the i
47:24
Speaker 1: heart Radio app, Apple Podcasts, or wherever you listen to
47:28
Speaker 1: your favorite shows. Ye