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00:00Charles, welcome back to my office.
00:01Thank you for having me.
00:02All right, you know, I have an issue
00:04with the wave-particle duality.
00:06I don't.
00:07Coming up.
00:08So Charles, we'll be talking about quantum physics.
00:23You just wrote a book on quantum physics.
00:25Yes, I did.
00:26The Handy...
00:27Quantum Physics Answer Book.
00:28The word handy and quantum physics
00:30in the same title is a little disturbing.
00:33Nah, quantum is all around us.
00:36We experience it, we use it daily,
00:38and we don't even know it.
00:39So handy is really trying to convince people
00:43that look, you don't have to be a quantum physicist
00:46to appreciate and use and enjoy the fact
00:49that we live in a universe that has quantum components.
00:53When we come of age in physics,
00:56and then you learn some things
00:58that are just true,
01:00but you're not invited to question it.
01:05Yet, that's right.
01:06We say, all right, here's a particle.
01:08Electron, proton, neutron, even photon.
01:11I don't mind calling that a particle,
01:13even though it's like...
01:14It totally is a particle.
01:15Okay.
01:15Absolutely, it's massless.
01:16We say the particle can also be a wave.
01:19You know, that's a very interesting point.
01:20I wanna compare notes with you
01:21about how you learned wave-particle duality.
01:24Because I went through the educational system
01:27a few years after you did.
01:29And it might have been a transition.
01:32You think something magic happened between those two times?
01:34In the pedagogy, not in the physics.
01:37Okay.
01:38In other words, when I was brought in through the system,
01:41the first thing I was told was that waves and particles,
01:46everything is a wave and a particle.
01:48That was not the first thing that I was taught.
01:50That is really true.
01:51Yeah, because in...
01:52That's later in the book.
01:53In high school physics,
01:55straight up ordinary high school physics,
01:58I was taught the de Broglie relation.
02:01It relates the momentum of a particle to its wavelength.
02:04And the relationship is mediated,
02:07shall we say, by Planck's constant.
02:08Wait a minute, I pronounced it de Broglie.
02:10Is that not right?
02:11My high school physics teacher, Walt Nazarenko,
02:14said right away, that first class,
02:16saying, in French, it's de Broglie.
02:18In America, we say de Broglie.
02:20So be ready to call it the de Broglie wavelength.
02:22Okay.
02:23No, but I wanna do right by the man's name.
02:25Louis de Broglie, okay.
02:26Louis de Broglie.
02:27Yeah, de Broglie.
02:28Louis, he saw the mathematical connection, right?
02:34As early as 1900, when Max Planck published
02:38the Planck equation, that we call it today now,
02:41for thermal radiation, black body spectrum.
02:44Which many people forget, or don't associate,
02:49that was the birth of quantum physics.
02:51Absolutely.
02:51In the year 1900.
02:53But we wouldn't really develop it until the 1920s.
02:56And I'm the first out of the box to say
02:59that we are now in the centennial decade
03:02of the discovery of quantum physics.
03:04Because most of that happened in the 1920s.
03:06The wave-particle duality at that point
03:09was when the tension was set, right?
03:11Because Planck showed that he could figure out
03:14the thermal radiation spectrum
03:16if he treated photons as particles.
03:19Max Planck, quite a very interesting individual.
03:22The history of how he went through life.
03:24In his early times, he was considered
03:27a little bit on the fringe.
03:29Because he was talking about things like the Planck length
03:31and the Planck time, and things like that
03:33were really short, not anything terrestrial.
03:36Did he use his own name when he was a doctor?
03:37No, no.
03:38He just said.
03:39My name is Planck, and here's a Planck length.
03:40If you take the Planck constant,
03:43which back then he didn't even call that, right?
03:45Planck's constant.
03:45If you take the constant that sort of knits
03:47quantum physics together, and then the gravitational
03:49constant and the speed of light,
03:51and you start doing dimensional analysis on them,
03:53you get lengths, you get times.
03:55And he was like, you know, these were probably
03:57fundamental to the universe.
03:59And people were like, what?
04:00A billionth of a billionth of a billionth of an inch?
04:03No, that couldn't be fundamental.
04:06Little did we know that with quantum physics, right?
04:09And the wave particle duality.
04:11So you're saying you never had a problem
04:13simultaneously thinking about particles and waves
04:18being one and the same.
04:18That's right.
04:19Why not?
04:21Unless it's just, it is so,
04:25therefore I will accept it as so.
04:27You're telling me you didn't stay up at night
04:30wondering about it?
04:31Never.
04:32That doesn't mean, by the way,
04:33that I was able to do the mathematical calculations.
04:36Okay, I was up there struggling with all of them,
04:40except for some of my really talented and skilled colleagues.
04:44Back then they were just fellow students.
04:46I couldn't do the math really well.
04:48So it was really hard for me to grasp the connections.
04:51But the concept that you and I are particles,
04:53you know, I mean, I shake all the time, right?
04:56I definitely have a wavelength.
04:57You have a wavelength.
04:59Are we on the same wavelength?
05:01No, no, but there are other quantum principles
05:05that are widely misunderstood, but I find intuitive.
05:10All right, so one of them relates
05:12to the Heisenberg uncertainty principle.
05:13So the way it gets misconstrued, of course,
05:17is people say, there's the observer effect.
05:20And is your consciousness affecting the experiment?
05:22Oh my gosh, let's hand it over to the new age folks
05:25and let them solve it.
05:26And this is a complete misunderstanding of quantum physics.
05:30And so when you explain it and you say,
05:33well, we are big macroscopic objects.
05:35If you're gonna take a picture of us,
05:37turn on the lights and we take a picture.
05:39But the smaller you are, no longer are you so immune
05:45to the consequences of being illuminated by photons.
05:48Right, and so if I'm a particle,
05:52and I say, I wonder what the particle's doing?
05:54Let me take a picture.
05:55And then you turn on the light,
05:57the particle's doing something else.
05:59So there's a limit to how much you can know about the system
06:02just because the act of observing it
06:04changes what it is you think it's doing.
06:06So that made complete sense to me,
06:08but it's a foundational tenet of quantum physics.
06:11But still, sometimes I'm a wave,
06:13sometimes I'm a particle,
06:14depending on how you think about it
06:16or look at it or measure it.
06:17I'm still, I accept it,
06:19but I can't claim that that's intuitive.
06:21Let me express something that might help.
06:24Is that because it's intuitive to you
06:25or you're just accepting what we know
06:27is an objective reality?
06:28It's intuitive to me.
06:29Something can be a particle and a wave at the same time.
06:33It's just mathematically hard to express that.
06:35In the same way that you can be both tall
06:40and you can be-
06:42You said it, not me.
06:45It's just a way of describing things.
06:48Every particle in the universe has a number of parameters.
06:53We call them quantum numbers, right?
06:55That describe what they are.
06:56One of those quantum numbers could be its mass as a particle
07:00and another of those quantum numbers is its wavelength.
07:03It's an attribute.
07:04Yeah, it's an attribute.
07:04So, but then you have the double slit experiment.
07:06So you have two slits and you send waves through it
07:10and they interfere with each other on the other side.
07:13So the crests match up in some places
07:16and you get higher intense wave
07:18and then they cancel out in other places.
07:20So it's called interference pattern, of course.
07:22So on the other side you see this,
07:24but if I send electrons on purpose-
07:29Yeah, one at a time.
07:30Through, one at a time,
07:31they'll either gather here or gather here
07:33and you have two bumps of electrons.
07:36Yeah.
07:37Isn't that funny?
07:38And you okay with that?
07:38100% okay.
07:41Again, I accept it.
07:42I'm just-
07:43It's a fascinating mystery though, isn't it?
07:45What was that?
07:46Got it.
07:47Mystery, you said it.
07:48Yes, it's a fascinating mystery of the nature of things.
07:51It works mathematically.
07:53It's shown experimentally over and over again,
07:56but it doesn't mean it's not mysterious.
07:58It's a conditional attribute.
08:02So should we still call it an attribute?
08:04Sure, if I am looking at you through, say, a glass window,
08:10you look a certain way.
08:12If I put an aluminum sheet between you and me,
08:16you look a different way.
08:17In fact, I can't see you at all through visible light.
08:19But if I had radio eyes, or if I had infrared eyes,
08:23or if I had x-ray eyes, I would see different things.
08:26So it's not at all a conditional reality
08:30of are you different when I look through different things.
08:33It is conditional if one time it shows up
08:36as though it were particles,
08:39and another time it manifests as a wave.
08:42They're not both at the same time.
08:44But you changed the way you were looking at them.
08:46Yes.
08:47Right, you changed the way that you were producing them.
08:51You changed the way that you sent them towards the screen.
08:52Okay, so that means we cannot think of them
08:54in absolute terms.
08:56Right.
08:57By the way, this was a big problem
08:59that Alan Stern, Mr. Pluto Man, had.
09:03He didn't want the definition of a planet
09:05to be conditional on where you found the object.
09:09It should be a planet no matter where it is in the universe.
09:13Just to remind people, of course,
09:15one of the definitions of a planet is
09:17in its location in orbit around the sun,
09:20it needs to be the dominant mass of that orbit,
09:23basically having cleared its orbit.
09:25Pluto has not done that.
09:27Therein comes the more human side of the physics
09:32that maybe is the root of this particular problem.
09:35We use words to express what we mean about things.
09:39And those words are necessarily incomplete.
09:42No single term or word or sentence or definition
09:46can show all the shades of meaning of any particular thing.
09:49So if I'm talking about a planet here in our solar system,
09:53I don't mean a planet outside our solar system
09:56for which there's a different definition,
09:58or a planet that's just passing through our solar system.
10:01Right, every word is a little bit different.
10:03And so that causes a lot of problems, too.
10:05Okay, so I was a big fan of the word wavicle,
10:08but it didn't catch on,
10:10because I think it didn't rest comfortably within people.
10:13It's possible.
10:14Because how could it be a wave
10:16and a particle at the same time?
10:17So I thought maybe the word would influence
10:20the way you think about it,
10:21as is so often the case with language.
10:25Yeah, and that does happen, too.
10:26It changes people's minds as you slowly use different words
10:30for better or worse.
10:32Let me think about also the term power pack, right?
10:35We bring power packs with us to charge our phones
10:37if we're low on battery.
10:38They're not power packs, they're energy packs.
10:41The power is how fast the energy gets moved
10:44from one thing to the next.
10:45So we have this fundamental misunderstanding.
10:47But you mean physics precise about it?
10:48Right, and so if you wanna be astronomy precise
10:51about planet, or if you wanna be quantum precise
10:53about wave, particle, duality,
10:55therein lies, I think, the main issue
10:58that we will have in convincing everybody
11:01that everything is a wave and a particle
11:03at the same time.
11:04But I think if it was not an issue,
11:05we wouldn't use the word duality
11:06to describe the two words.
11:08That's historical also.
11:10It's not a duality that you are a given height
11:13and look differently in infrared light.
11:15That's not a duality.
11:16No one is thinking of that as a duality.
11:18I think you're right.
11:19In the 1920s, 1930s, wave-particle duality was a problem.
11:23That's why it got-
11:24It's people coming out of classical physics.
11:25Right.
11:26There was no room for that.
11:27That's right, it got into our world, right?
11:29Lord Kelvin, when he first proposed
11:32the two clouds blocking 20th century physics,
11:36a lot of people nowadays have misinterpreted that saying.
11:38He's saying, oh, there are only two problems left
11:40in all of physics.
11:41They're things that aren't quite adding up exactly.
11:44And it turned out that one of them was solved
11:46with relativity and the other one was solved with quantum.
11:48All right, but there still are people out there
11:50trying to bring classical sensibility to quantum physics,
11:54and I think they're just, they're barking up the wrong tree.
11:57They need a different mindset in order to embrace
12:00all the weirdness that quantum physics brings us.
12:04I don't want to cut off anybody's attempts
12:07to interpret the universe however way is most effective
12:10and provides insights.
12:11That's the kind of view.
12:12Yeah, but we can live with, and we all should live with,
12:16the idea that we are all waves and particles simultaneously.
12:21You heard it here first.
12:22Hi, Charles, I love chatting with you.
12:26Always a pleasure.
12:27So you've been eavesdropping on my conversation
12:30with my friend and colleague, Charles Liu,
12:33about quantum physics.
12:34The good, the bad, the ugly.
12:35And the beautiful.
12:36Especially the beautiful.
12:38Till next time, keep looking up.