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Speaker 1: Hey, Daniel, When you think about a photon, what image

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Speaker 1: comes to mind? Oh? Depends on what what you've been

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Speaker 1: smoking that day?

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Speaker 2: Yes, and also on the context. Are we talking about

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Speaker 2: light from distant stars or rainbows or single photon lasers

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Speaker 2: or what?

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Speaker 1: What? Aren't they all the same? Like a photon is

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Speaker 1: a photon, isn't it?

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Speaker 2: Nobody really knows what a photon is. There's something weird

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Speaker 2: and mysterious we might never fully understand.

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Speaker 1: So you're just gonna leave us in the dark. You're

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Speaker 1: not gonna shed any light on it.

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Speaker 2: That's as bright as I can be on the topic.

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Speaker 1: I am wore handmade cartoonists and the author of Oliver's

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Speaker 1: Great Big Universe.

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Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor

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Speaker 2: at UC Irvine, and I'm still hunting for a brilliant

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Speaker 2: explanation about photons.

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Speaker 1: I thought brilliance was your job description. Isn't it your

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Speaker 1: job to provide that brilliance.

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Speaker 2: My job is to hunt for the brilliance, to try

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Speaker 2: to mine the truth from the firmament of reality. We

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Speaker 2: don't always find it.

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Speaker 1: M I guess it's hard to shine light on some

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Speaker 1: of the corners of the universe that are hard to see.

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Speaker 1: We just have to hope somebody out there is bright enough,

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Speaker 1: somebody has a light bulb moment there. But what do

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Speaker 1: you mean? Are you saying photons depend on where they

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Speaker 1: come from?

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Speaker 2: I'm saying that the language of physics we use to

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Speaker 2: explain things uses as the basic mental building blocks. Things

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Speaker 2: We do understand waves and bits of sand and tiny

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Speaker 2: little particulate stuff, and none of those things really completely

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Speaker 2: and fully describe the photon. It's those things, but also

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Speaker 2: something else.

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Speaker 1: I see. It's a language issue. Blame it on the

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Speaker 1: linguists if we don't understand the universe. Yes, it's not

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Speaker 1: the physicists fault.

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Speaker 2: It also turns out to be fundamental to how we

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Speaker 2: do science. We often tell different stories about the same

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Speaker 2: kind of stuff depending on the question we are asking.

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Speaker 2: None of our science is totally exact and complete. It's

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Speaker 2: always approximate. And which approximation, which idea we use, which

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Speaker 2: conceptualization is relevant, depends on the questions we're asking.

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Speaker 1: Sounds like it's a big relativity problem because it's all relative.

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Speaker 2: It's relatively complicated.

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Speaker 1: Yeah, indeed, But anyways, welcome to our podcast. Daniel and

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Speaker 1: Jorge Explain the Universe, a production of iHeartRadio.

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Speaker 2: In which we take the whole universe as the context

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Speaker 2: for our goal to understand things. We want to understand

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Speaker 2: how droplets form into hurricanes, how tiny little quarks make protons,

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Speaker 2: how enormous masses of stuff swirl into black holes. We

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Speaker 2: want to answers for everything, and we hope one day

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Speaker 2: to be able to stitch those answers together into a single, comprehensive,

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Speaker 2: complete understanding of the universe, even though that might actually

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Speaker 2: be impossible.

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Speaker 1: Yeah, we try to track the journey of humanity from

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Speaker 1: the shadows into the shining light of understanding and comprehension

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Speaker 1: about this amazing universe we live in. Yeah, even if

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Speaker 1: it sometimes takes a few stories or different stories along

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Speaker 1: the way.

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Speaker 2: The history of physics is seeing stuff we don't understand

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Speaker 2: and then cobbling together some sort of mathematical explanation for

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Speaker 2: what might be going on. And the bigger picture is

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Speaker 2: to then try to weave those explanations together into a

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Speaker 2: single coherent idea. But that task is still not finished,

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Speaker 2: and it leaves us sometimes in an awkward situation of

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Speaker 2: not being able to answer pretty basic questions about what's

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Speaker 2: going on out there?

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Speaker 1: Are you saying physicists can't get their story straight. It's

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Speaker 1: a little suspicious.

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Speaker 2: I'm saying the universe is a little bit lack Russiamon.

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Speaker 2: You know, the story you tell depends on your context.

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Speaker 2: But this is not something that only physicists do. You know,

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Speaker 2: if I ask you how the baseball game went yesterday,

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Speaker 2: you tell me a story about the teams and who

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Speaker 2: was playing well and who was struggling. You put it

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Speaker 2: in context to make it exciting. You don't just give

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Speaker 2: me a dry list of what happened to every single

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Speaker 2: particle in the vicinity of the stadium that day.

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Speaker 1: But there'd just be one story about who won and

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Speaker 1: who lost.

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Speaker 2: If you think that's the story, right, Maybe the story

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Speaker 2: is something else, the changing of the hot dogs, how

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Speaker 2: the mustard now tastes, you know, the weather. Everybody might

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Speaker 2: ask different questions about the same sets of events, and

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Speaker 2: then they might need to use different physical concepts, even

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Speaker 2: different mathematical formalisms to get those answers, which makes a

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Speaker 2: very complicated answer very basic sounding questions.

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Speaker 1: Right, right, Sometimes you need hot dog particles, sometimes you

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Speaker 1: need baseball particles.

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Speaker 2: Yeah, exactly. You can build a whole universe. On the

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Speaker 2: hot dog theory, hot dogs are the fundamental component and

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Speaker 2: what's inside them doesn't really.

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Speaker 1: Matter, right, right, is it the hot dog on or

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Speaker 1: the hot legino?

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Speaker 2: The whole brilliance of hot dogs is just enjoying them

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Speaker 2: and not even caring what they're made at it.

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Speaker 1: What's the shape of a hot dog on? And how

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Speaker 1: long is it?

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Speaker 2: That depends on which city you're in, you.

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Speaker 1: Know, yeah, yeah, or which country too.

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Speaker 2: That's right. And your relative velocity, because some of these

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Speaker 2: things can be length contracted.

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Speaker 1: That's right. If you eat it fast, then it's a

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Speaker 1: lot shorter than it is.

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Speaker 2: If you're at high velocity relative to your hot dog,

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Speaker 2: it will seem shorter. So, yeah, somebody shoots a hot

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Speaker 2: dog into your mouth near the speed of light, then

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Speaker 2: you're gonna have an interesting experience.

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Speaker 1: But then it depends on which direction it is subndy, Right,

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Speaker 1: if it's shutted on the side, it's still going to

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Speaker 1: be the same length.

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Speaker 2: Yeah, exactly, it's just going to be thinner.

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Speaker 1: Yeah, let's just spend the rest of the episode talked

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Speaker 1: about hot dog physics.

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Speaker 2: High velocity hot dog physics, relativistic hot dog physics, A

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Speaker 2: topic nobody has ever explored. We can be the first

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Speaker 2: to write a paper in the Journal of Hot Dog Physics.

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Speaker 1: Well, I think we're definitely the first to ever talk

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Speaker 1: about it in a physics podcast. I'm thinking, I don't know.

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Speaker 1: I haven't done the exhaustive literature search.

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Speaker 2: Somebody out there let us know if we need to

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Speaker 2: cite you.

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Speaker 1: Yeah, somebody else do the research for us. But anyways,

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Speaker 1: it is interesting to talk about how long things are,

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Speaker 1: you know, basic questions like that about everyday objects we

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Speaker 1: see every day.

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Speaker 2: It is often really fruitful, but sometimes frustrating to ask intuitive,

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Speaker 2: natural questions about the kind of things we think the

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Speaker 2: universe is made out of. We think everything out there

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Speaker 2: has certain properties, it has a size, a link, the mass,

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Speaker 2: et cetera. And so we try to apply those concepts,

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Speaker 2: these things we're familiar with from the kind of stuff

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Speaker 2: we're used to interacting with, and apply that to quantum objects.

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Speaker 2: But it doesn't always quite work.

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Speaker 1: Yes, we've found out the quantum world is very straying,

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Speaker 1: very mysterious, very uncertain, and very hard for our simple

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Speaker 1: brain sometimes to understand and capture and to get an

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Speaker 1: intuitive understanding of it.

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Speaker 2: But that doesn't mean it's impossible, and that doesn't mean

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Speaker 2: it's not useful. In fact, it's very helpful for shining

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Speaker 2: a light onto what we do understand and what we

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Speaker 2: don't understand, and it can help you make a better

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Speaker 2: mental picture for what's going on at the quantum level.

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Speaker 1: Right, But the question is can we shine a light

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Speaker 1: on light itself? And so to be on the podcast

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Speaker 1: jagging the question how long is a photon? Now it is?

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Speaker 1: Is that a photon coming off of a hot dog?

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Speaker 1: Or does it matter where it's bouncing off of.

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Speaker 2: A hot dog? Colored photon?

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Speaker 1: Wow? What is the color of a hot dog? What

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Speaker 1: is the color of a hot dog? Sounds like the

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Speaker 1: topic of a philosophy class here.

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Speaker 2: If you eat your hot dog with eyes closed, does

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Speaker 2: it have a color or not? I wonder if there's

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Speaker 2: a paint shade out there that's called hot dog.

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Speaker 1: I think people usually avoid having their runs painted hot dog.

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Speaker 2: There's probably more adjectives to it, like bright, summer hot dog.

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Speaker 1: Or something summer baseball hot dog, home run, the hot dog,

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Speaker 1: hot dog, vapor, wild mountain hot dog. There's so many

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Speaker 1: shades to a hot dog, isn't there?

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Speaker 2: But we're not here to talk about hot dogs, though

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Speaker 2: it seems like we're gonna We're here to try our

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Speaker 2: best to answer a very simple but very hard question

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Speaker 2: about the nature of light.

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Speaker 1: Mmm, Now, how long it's a photon? Is that a

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Speaker 1: question about its length or like how long it lasts?

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Speaker 2: Oh? I interpreted it as a question about its length,

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Speaker 2: like its physical extent. Photons can last forever, you know,

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Speaker 2: their lifetime is potentially infinite. You shoot a photon into

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Speaker 2: empty space, it'll just keep going forever.

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Speaker 1: But you can kill a photon, can it?

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Speaker 2: You can kill a photon, yes, absolutely, you can absorb it,

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Speaker 2: you can interact with it. But a photon on its

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Speaker 2: own will not like necessarily.

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Speaker 1: Decay, can it ever, like, is there a possibility for

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Speaker 1: it to, you know, have its energy convert into something else?

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Speaker 2: Absolutely? A photon flying through space can just fly through space.

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Speaker 2: But it can also turn into an electron and positron

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Speaker 2: and then back into a photon, or into a muon

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Speaker 2: or an anti muon and then back into a photon,

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Speaker 2: or all sorts of other stuff. So there's lots of

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Speaker 2: quantum possibilities constantly for photons.

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Speaker 1: Can it turn into a hot dog technically? Like you know,

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Speaker 1: in the infinity of infinities. Is there us light chance

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Speaker 1: it can turn it suddenly into hot dog?

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Speaker 2: Yes, there's a slight chance a very high energy photon

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Speaker 2: could turn into a mutually charged hot dog momentarily.

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Speaker 1: Hopefully it doesn't turn into hot dog inside your eye.

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Speaker 2: And that tells me exactly what I want to paint

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Speaker 2: my room next year, which is quantum hot dog.

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Speaker 1: Oh boy, it's like it's different shades at the same.

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Speaker 2: Time, exactly Shrewdinger's hot.

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Speaker 1: It's like yellow mustard red ketchup. But it depends on

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Speaker 1: how you look at it, kind of like the dress. Anyways,

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Speaker 1: that's a very spicy idea. All right, let's talk about

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Speaker 1: this question. But first we were wondering how many people

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Speaker 1: out there had thought about the length of a photon,

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Speaker 1: or even if photons have length.

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Speaker 2: Thanks very much to everybody who answered this question. I

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Speaker 2: only got one response online. So I walked around campus

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Speaker 2: at you see Irvine last week and I asked a

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Speaker 2: bunch of psych majors and other random people about photons.

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Speaker 1: All right, Well, if you spot a physicist with a

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Speaker 1: microphone on the ucroline campus, make sure to I don't know,

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Speaker 1: runaway or approach if you think you can answer physics

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Speaker 1: questions on the.

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Speaker 2: Spot, or even if you don't, I love to hear

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Speaker 2: your thoughts.

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Speaker 1: All right, So think about it for a second. How

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Speaker 1: long do you think a photon is? Here's what people

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Speaker 1: had to say.

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Speaker 2: I don't think.

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Speaker 1: We don't know about that yet because of the mathematics

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Speaker 1: going weird, since the photon is traveling in speed of

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Speaker 1: the light.

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Speaker 2: So that's my guess. Oh my gosh, I don't know.

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Speaker 1: I'm gonna say and like, uh like ten to the

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Speaker 1: power of negative twenty centimeters.

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Speaker 3: Let's say, so I guess photons they don't have a

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Speaker 3: mask or that have amentin right an, So it depends

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Speaker 3: on the wave length light.

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Speaker 4: No, I wouldn't even have like a guess of like

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Speaker 4: length yeah a long in science, yeah.

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Speaker 1: Phot I don't even know the pot I remember from biocam, okay,

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Speaker 1: like maybe in chips.

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Speaker 4: Yeah, I wouldn't even know I would photons. When I

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Speaker 4: think of physics, I think get like small like particles. Yeah,

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Speaker 4: and then I'm thinking like centimeters and like in minute

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Speaker 4: signs two millimeters.

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Speaker 2: I don't.

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Speaker 1: I don't even know what a photon is. I major

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Speaker 1: in a criminal justice, so completely outside of my major

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Speaker 1: there's a photon, a particle light.

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Speaker 2: Yes, how long is it?

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Speaker 1: I'm gonna say point zeros are one light years. I

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Speaker 1: don't know, like some ran like maybe like zero point

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Speaker 1: one microns.

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Speaker 4: I don't know.

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Speaker 1: All right, some pretty good answers. Some of them are

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Speaker 1: very specific. Zero point one microns ten to the power

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Speaker 1: of negative twenty centimeters.

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Speaker 2: There's a huge, huge range of answers here. I think

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Speaker 2: the biggest one is probably zero points zero zero one

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Speaker 2: light years. That turns out to be a very big number.

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Speaker 1: Well, I'm impressed that they even stuck to the metric system.

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Speaker 1: I mean, everyone nobody switched to inches or miles.

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Speaker 2: You think photons are metric? I don't know. Yeah, I

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Speaker 2: believe in imperial photons.

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Speaker 1: I believe photons are king, but you know, I think

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Speaker 1: they should stick to the more reasonable metric system.

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Speaker 2: That's why Darth Vader is all black, because there are

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Speaker 2: no imperial photons.

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Speaker 1: Wow, reach there took me three seconds there wait? Oh

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Speaker 1: imperial Yes, Yes, that was a very dark joke. I

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Speaker 1: thought you were going to go with a lightsaber response.

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Speaker 1: I totally set you up for that. What would be

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Speaker 1: the lightsaber joke?

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Speaker 2: Lightsabers only cut things in metric units. I don't know.

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Speaker 1: Lightsabers are about a meter long. There you go, all right,

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Speaker 1: well interesting azers. So Daniel to dig into it. For

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Speaker 1: first of all, what is a photon? How do we

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Speaker 1: define a photon? So, photon is like the minimum packet

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Speaker 1: of light. If you take a really bright source of light,

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Speaker 1: you might imagine it's just shooting out huge amounts of light.

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Speaker 1: As you dial it down, it'll get dimmer and dimmer

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Speaker 1: and dimmer, but it can't get infinitely dim. As you

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Speaker 1: dial that light source down, eventually you'll notice that the

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Speaker 1: light is actually discreete that it comes out in little

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Speaker 1: packets rather than just being dimmer and dimmer waves. So

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Speaker 1: photons are like the minimum unit of light. Wait are

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Speaker 1: you saying that photons don't have a minimum energy.

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Speaker 2: Photons do not have a minimum energy. That's true, but

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Speaker 2: photons of a specific frequency have a fixed energy. And

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Speaker 2: if you have, for example, a laser at his very

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Speaker 2: specific wavelength and you dial it down so it's dimmer

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Speaker 2: and dimmer and dimmer, eventually you're going to notice that

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Speaker 2: beam gets broken up and it comes out in pieces.

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Speaker 1: Like you lower the power to the laser, and eventually

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Speaker 1: you'll see it go down steps.

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Speaker 2: Yeah, exactly. It's just like everything else in our quantum world.

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Speaker 2: Matter is not continuous. You can't zoom in forever on

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Speaker 2: matter and have it always look the same way you

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Speaker 2: zoom in on matter. You notice that it has a

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Speaker 2: particular scale that at some point it breaks up into

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Speaker 2: discrete bits out of which everything is built, just like

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Speaker 2: the resolution on your screen. So light itself has a resolution.

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Speaker 2: It's made out of these little quantum bits, these discrete

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Speaker 2: building blocks. It's not perfectly smooth. And what is that

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Speaker 2: smallest bit for light? It's a photon. That's what we

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Speaker 2: call the photon. It's the smallest bit of light.

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Speaker 1: Like if I if I'm shooting lighters are in frequency,

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Speaker 1: the little steps that I see as I dial down

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Speaker 1: the power to it, that's what you would call a photon.

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Speaker 2: Exactly. Those are photons. And so if you have a

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Speaker 2: bunch of light, you can always ask how many photons

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Speaker 2: are there. There's a specific number. It has to be

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Speaker 2: an integer number of photons. You don't usually notice this

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Speaker 2: because the number of photons usually around hitting your eyeball

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Speaker 2: is enormous. It doesn't really matter that they're countable. But

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Speaker 2: as things get very very small. Then you can notice

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Speaker 2: that you can have zero or one or two photons,

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Speaker 2: you can't have one point seven photons.

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Speaker 1: Now, how do we think about light? Is it like

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Speaker 1: you say, it's like a packet, Like it's a discrete

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Speaker 1: little object.

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Speaker 2: Yeah, So this really gets at the heart of the

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Speaker 2: question because how you describe this object helps you answer

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Speaker 2: the question how big is it? And the answer is

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Speaker 2: that we think about light in lots of different contradictory ways,

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Speaker 2: depending on the context. Sometimes we think about light as

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Speaker 2: like a tiny little object, but we think about it

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Speaker 2: like a particle which has no extent, just like zero

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Speaker 2: volume particle. Sometimes we ignore the quantum nature of it

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Speaker 2: because it doesn't matter. We're thinking about really bright sources

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Speaker 2: where the quantum nature is irrelevant, So we just think

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Speaker 2: about it as classical waves of electromagnetism, the way people

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Speaker 2: did two hundred years ago. And sometimes we think about

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Speaker 2: light interacting with quantum particles, like light hitting an electron,

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Speaker 2: and then we think about it as a little quantum

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Speaker 2: packet and excitation in the electromagnetic field. So we have

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Speaker 2: lots of different pictures of what a photon is, and

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Speaker 2: the one that we use depends kind of on the question,

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Speaker 2: we're asking.

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Speaker 1: Well, so do you want to then tackle each one

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Speaker 1: of these different ways to look at it at a time?

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Speaker 2: Yeah? Sure. I think probably the most relevant in this

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Speaker 2: case is the quantum field theory one the last one

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Speaker 2: we talked about, But each one gives you a different answer.

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Speaker 1: All right, well, then let's maybe tackle each one of these.

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Speaker 1: But what does quantum field theory say about the nature

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Speaker 1: of light?

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Speaker 2: Quantum field theory is an updated version of classical field theory,

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Speaker 2: which sounds fancy, but it just says light is a

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Speaker 2: wave in the electromagnetic field. That's what Faraday and Maxwell

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Speaker 2: and those guys figured out a couple of hundred years ago,

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Speaker 2: that the universe is filled with this electromagnetic field and

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Speaker 2: that waves in it are what we call light, and

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Speaker 2: so you can shoot light from one planet to another,

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Speaker 2: and the medium for that is the electromagnetic field. Even

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Speaker 2: though space is empty, it has these fields in it.

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Speaker 2: So light is a ripple in those fields. And we

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Speaker 2: talk about that all the time on the podcast. And

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Speaker 2: you have electric fields and magnetic fields and there are

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Speaker 2: ninety degrees from each other and they're oscillating, and that's

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Speaker 2: what light is. From a classical point of view. That's

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Speaker 2: a traditional classical field theory. The quantum field theory version

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Speaker 2: of that is the same. It just says that there's

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Speaker 2: a minimum to how you can oscillate, so that as

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Speaker 2: you turn it down you discover that you can't turn

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Speaker 2: it to any intensity. There's certain steps. So the quantum

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Speaker 2: field theory version says the universe is filled with this

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Speaker 2: electromagnetic field which has certain steps in energy that it

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Speaker 2: can take.

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Speaker 1: Well, I guess, first of all, I wonder if listeners,

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Speaker 1: as sometimes you get confused by this like I do,

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Speaker 1: which is that you say light is a wave, but

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Speaker 1: like if I think that's rippling through a field, But

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Speaker 1: if I think of a wave like rippling through a

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Speaker 1: lake or my bathtub, it's something that ripples outwards in

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Speaker 1: all directions. Or if I think of it like a

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Speaker 1: wave in the ocean, it's like this broad thing that's

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Speaker 1: moving and undulating across kind of a wide area. But

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Speaker 1: in terms of light, it's not that right. It's not

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Speaker 1: spreading in all directions, and it's not broad like that.

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Speaker 2: It can be though, I mean, think about a star.

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Speaker 2: A star is emitting light, and it's emitting light in

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Speaker 2: all directions, and before you think about the quantum nature

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Speaker 2: of it, it is in fact spreading out. And that's

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Speaker 2: why stars seem more dim the further you are away

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Speaker 2: from them, right, because the intense see the light drops

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Speaker 2: with the distance squared, and so you have light waves

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Speaker 2: which start out very intense and then they spread out

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Speaker 2: and so they get dimmer and dimmer. The quantum version

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Speaker 2: of that is the same, except that now you have

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Speaker 2: individual photons being sent out and close to the star

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Speaker 2: you have a high intensity of those photons, and further

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Speaker 2: away you have a smaller intensity of those photons. And

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Speaker 2: you can understand why the intensity the photon drops as

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Speaker 2: you get further away because the space they're feeling is

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Speaker 2: getting bigger and bigger. And so if you have like

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Speaker 2: the same size eyeball and you're gonna have fewer number

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Speaker 2: of photons hit your eyeball when you're further away than

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Speaker 2: when you are close up to the star.

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Speaker 1: Right, you can sorder think about it that way. But

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Speaker 1: I guess what do you call the photon? Then? Is

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Speaker 1: the photon the ripple that's shooting in all directions or

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Speaker 1: just if you catch that ripple in a particular spot.

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Speaker 1: You know what I mean? Like you can imagine a

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Speaker 1: star and it's rippling light out. Is a photon that

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Speaker 1: a ring that emanates from the star or what?

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Speaker 2: Yeah, great question. Say you slow the star down so

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Speaker 2: it's only emitting one photon at a time somehow, right,

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Speaker 2: like a single photon star. Basically, we're just putting a

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Speaker 2: laser out there in space, but it's interesting to think

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Speaker 2: about how it could go in any direction. So then

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Speaker 2: any individual photon has the same probability to go in

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Speaker 2: any direction from the star if it's totally symmetric. And

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Speaker 2: so an individual photon has a ring of probability around

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Speaker 2: the star where it can go, and then when it

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Speaker 2: actually hits something, then the universe decides, Okay, this one's

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Speaker 2: over here or this one's over there. It's just like

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Speaker 2: when you shoot photons at a screen. They have a

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Speaker 2: range of possible locations where they can land, and then

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Speaker 2: when the photon actually hits, that's when the universe decides

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Speaker 2: this photon's over here and this photon's over there. So yeah,

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Speaker 2: individual photons come out in only one direction, but they

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Speaker 2: have a probability to come out in any direction. There's

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Speaker 2: a bit of a quantum.

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Speaker 1: Wrinkle there, So it's a little bit like the Schrodinger's cat.

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Speaker 1: I know you don't always like this analogy, but it's

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Speaker 1: sort of like the photon as it comes out of

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Speaker 1: the sun or the star. It's in all directions at

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Speaker 1: the same time.

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Speaker 2: It has the possibility the probability to be in all

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Speaker 2: directions at the same time. You can only ever observe

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Speaker 2: it in one. So it depends what you mean by

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Speaker 2: like it is in those places at the same time,

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Speaker 2: it has the possibility to be there can ever be

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Speaker 2: seen to be in more than one place at once.

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Speaker 1: So like it emanates like a bubble basically out of

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Speaker 1: the star, that ripple that's the photon technically, right until

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Speaker 1: something hits it, or until it hits something in my

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Speaker 1: role to die and say okay, yeah that's where I

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Speaker 1: was at.

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Speaker 2: Yeah that's right.

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Speaker 1: So then these ripples, these bubble ripples have a wavelength

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Speaker 1: to them.

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Speaker 2: Yeah, exactly, So these bubble ripples have a wavelength, right.

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Speaker 2: High energy photons have a very short wavelength, like blue

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Speaker 2: photons have a shorter wavelength a higher frequency than red photons,

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Speaker 2: which have a longer wavelength and a shorter frequency. And

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Speaker 2: so that immediately feels like ooh, that might be part

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Speaker 2: of the answer that tells us about the length of

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Speaker 2: these photons, because red photons have a longer wiggle than

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Speaker 2: blue photons, which have a shorter wiggle. And the answer

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Speaker 2: is sort of in that direction. But it's not the

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Speaker 2: answer a red photon with a very specific energy. It's

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Speaker 2: the length of the photon, is not the wavelength of

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Speaker 2: that ripple.

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Speaker 1: Well, let's talk a little bit about this wavelength. How

443
00:21:11,080 --> 00:21:14,720
Speaker 1: do you measure this wavelength? Like, it's the distance at

444
00:21:14,760 --> 00:21:17,520
Speaker 1: which the ripple repeats itself.

445
00:21:17,840 --> 00:21:20,840
Speaker 2: Yeah, remember we're talking about a ripple in the electromagnetic field.

446
00:21:21,200 --> 00:21:24,320
Speaker 2: What is the electromagnetic field. It's a vector in space,

447
00:21:24,359 --> 00:21:26,800
Speaker 2: which means every point in space has an arrow with

448
00:21:26,880 --> 00:21:29,040
Speaker 2: a direction in it. That's confusing to you. You can

449
00:21:29,080 --> 00:21:31,560
Speaker 2: just pretend it's just a number. Don't worry about the vector.

450
00:21:31,680 --> 00:21:35,160
Speaker 2: And the wavelength tells you when the electromagnetic field returns

451
00:21:35,200 --> 00:21:38,800
Speaker 2: to its original value. Right, So the electromagnetic field is

452
00:21:38,840 --> 00:21:40,919
Speaker 2: pointing up and then it oscillates down, and then it

453
00:21:40,960 --> 00:21:43,400
Speaker 2: oscillates back up again. And this is just like the

454
00:21:43,440 --> 00:21:45,120
Speaker 2: direction of the electric field.

455
00:21:44,960 --> 00:21:47,720
Speaker 1: Meaning like it increases in value, like if I put

456
00:21:47,720 --> 00:21:50,080
Speaker 1: my finger in front of me, that's a point in space,

457
00:21:50,359 --> 00:21:53,000
Speaker 1: and that point in space has an electromagnet field going

458
00:21:53,040 --> 00:21:54,760
Speaker 1: through it, and that field can certainly have a value

459
00:21:54,760 --> 00:21:55,720
Speaker 1: where I'm pointing my finger.

460
00:21:56,080 --> 00:21:58,919
Speaker 2: The electromagnetic field has a value at every point in space. Yes,

461
00:21:58,960 --> 00:22:01,080
Speaker 2: it has a vector value, which means has a direction

462
00:22:01,520 --> 00:22:02,080
Speaker 2: and a length.

463
00:22:03,160 --> 00:22:05,080
Speaker 1: Right, But we're just talking about value, and so like

464
00:22:05,119 --> 00:22:08,480
Speaker 1: where I'm pointing my finger can suddenly go up in value,

465
00:22:08,720 --> 00:22:10,560
Speaker 1: Like it can be zero right now, zero zero, but

466
00:22:10,600 --> 00:22:11,800
Speaker 1: suddenly it can go up to ten.

467
00:22:11,960 --> 00:22:14,120
Speaker 2: Yeah, exactly. It can change with time.

468
00:22:14,680 --> 00:22:16,879
Speaker 1: And then it can go back down to zero. And

469
00:22:16,920 --> 00:22:17,639
Speaker 1: that's a ripple.

470
00:22:17,800 --> 00:22:19,760
Speaker 2: And if you want to think about the wavelength, you know,

471
00:22:19,800 --> 00:22:22,800
Speaker 2: you have your finger at one point, and the electromagnetic

472
00:22:22,800 --> 00:22:25,520
Speaker 2: field has a value there. If there's a photon moving

473
00:22:25,560 --> 00:22:28,200
Speaker 2: through space there, then if you could put another finger

474
00:22:28,280 --> 00:22:30,600
Speaker 2: somewhere else, you can ask where do I have to

475
00:22:30,600 --> 00:22:32,720
Speaker 2: put my other finger so it has the same value

476
00:22:32,720 --> 00:22:34,879
Speaker 2: as my first finger. And that's what the wavelength is

477
00:22:34,920 --> 00:22:37,560
Speaker 2: telling us. Because the wavelength tells us the electromagnetic field

478
00:22:37,600 --> 00:22:39,800
Speaker 2: goes up and then down, where does it come back

479
00:22:39,800 --> 00:22:43,280
Speaker 2: to its original value? That's the wavelength for blue photons.

480
00:22:43,320 --> 00:22:45,640
Speaker 2: Your two fingers be closer together and for red photons,

481
00:22:45,640 --> 00:22:47,200
Speaker 2: your fingers would be further apart.

482
00:22:47,359 --> 00:22:50,320
Speaker 1: And so light is like the value going up in

483
00:22:50,359 --> 00:22:52,320
Speaker 1: one of my fingers and down and then go up

484
00:22:52,359 --> 00:22:54,960
Speaker 1: and down in my other finger. But it only happens

485
00:22:55,000 --> 00:22:58,760
Speaker 1: once for each photon, Like a photon passing through is

486
00:22:58,840 --> 00:23:00,400
Speaker 1: just a one.

487
00:23:00,840 --> 00:23:03,080
Speaker 2: I understand why that's confusing, but that's not actually what

488
00:23:03,119 --> 00:23:06,280
Speaker 2: one photon is. And this is going to sound like nonsense,

489
00:23:06,320 --> 00:23:08,800
Speaker 2: But a single photon of specific energy, like if you

490
00:23:08,840 --> 00:23:12,840
Speaker 2: say exactly what the wavelength is, that photon actually has

491
00:23:12,880 --> 00:23:17,639
Speaker 2: an infinite size in space, like that photon exists everywhere

492
00:23:17,640 --> 00:23:19,680
Speaker 2: in the universe. I told you it was going to

493
00:23:19,760 --> 00:23:25,400
Speaker 2: sound like nonsense. I tried to warn, Well.

494
00:23:25,200 --> 00:23:26,880
Speaker 1: It sounds like we're going to get a pretty deep

495
00:23:26,920 --> 00:23:29,560
Speaker 1: into this, So why don't we take a quick break,

496
00:23:29,680 --> 00:23:32,000
Speaker 1: and then when we come back, we'll dig into what

497
00:23:32,080 --> 00:23:35,359
Speaker 1: it means for light to be everywhere, all at once.

498
00:23:35,640 --> 00:23:37,800
Speaker 1: So let's do that, But first let's take a quick break.

499
00:23:50,400 --> 00:23:53,840
Speaker 1: All right, we're talking about light and how long light is,

500
00:23:54,720 --> 00:23:57,520
Speaker 1: and Daniel, you just kind of blew our minds here

501
00:23:57,560 --> 00:24:00,399
Speaker 1: and said that light can be everywhere, all at one,

502
00:24:00,800 --> 00:24:03,960
Speaker 1: which is the name of a great movie which coincidentally

503
00:24:03,960 --> 00:24:05,359
Speaker 1: involved hot dog fingers.

504
00:24:05,920 --> 00:24:09,040
Speaker 2: That's true, not coincidentally. Man, that was the long term

505
00:24:09,119 --> 00:24:10,720
Speaker 2: plan for this whole joke. I was going to bring

506
00:24:10,760 --> 00:24:11,520
Speaker 2: it back together.

507
00:24:12,480 --> 00:24:15,040
Speaker 1: Yes, it was just a giant plug.

508
00:24:14,800 --> 00:24:19,880
Speaker 2: For a movie A twenty four. Send us some free passes.

509
00:24:19,880 --> 00:24:22,960
Speaker 1: Yeah, there you go. So we're talking about like a

510
00:24:22,960 --> 00:24:26,080
Speaker 1: photon is a giant bubble that emanates from a light source.

511
00:24:26,800 --> 00:24:29,720
Speaker 1: It's everywhere, all at once, in all directions until something

512
00:24:29,800 --> 00:24:32,919
Speaker 1: hits it. But then if I'm the person that it hits,

513
00:24:33,520 --> 00:24:35,920
Speaker 1: you're saying, it's not something that just washes over me.

514
00:24:36,160 --> 00:24:37,840
Speaker 2: Yes, So we're going to talk about the length of

515
00:24:37,880 --> 00:24:40,520
Speaker 2: a photon, then we have to know something about the

516
00:24:40,680 --> 00:24:43,399
Speaker 2: energy of the photon. Might think, hold on, isn't he

517
00:24:43,480 --> 00:24:47,440
Speaker 2: changing the subject. Remember that for quantum objects, their location

518
00:24:47,680 --> 00:24:50,040
Speaker 2: and the uncertainty in their location how well you can

519
00:24:50,040 --> 00:24:53,800
Speaker 2: pin that down, is intimately connected with their energy. The

520
00:24:53,800 --> 00:24:57,480
Speaker 2: Heisenberg uncertainty principle tells us that you can't know perfectly

521
00:24:57,480 --> 00:25:00,720
Speaker 2: well the energy of an object or it's momentum nearly

522
00:25:00,760 --> 00:25:05,240
Speaker 2: equivalently and its location. And so for a photon, if

523
00:25:05,240 --> 00:25:07,679
Speaker 2: you know exactly its energy, if I have a laser,

524
00:25:07,680 --> 00:25:11,600
Speaker 2: for example, which always puts out photons at one wavelength,

525
00:25:11,640 --> 00:25:14,360
Speaker 2: and I know it exactly those photons because we specify

526
00:25:14,440 --> 00:25:17,440
Speaker 2: their energy precisely. That means we can't know anything about

527
00:25:17,440 --> 00:25:20,560
Speaker 2: their location. And so, like the quantum field theory version

528
00:25:20,600 --> 00:25:23,840
Speaker 2: says that the whole universe, the electromagnetic fields of the

529
00:25:23,880 --> 00:25:28,960
Speaker 2: whole universe, has that photon in it. It's oscillating simultaneously everywhere.

530
00:25:29,400 --> 00:25:31,440
Speaker 1: And now I guess it's getting kind of hairy because

531
00:25:31,440 --> 00:25:33,879
Speaker 1: we just talked about how like a photon is a ripple,

532
00:25:34,040 --> 00:25:36,280
Speaker 1: like a bubble that emanates from a star or a

533
00:25:36,440 --> 00:25:39,440
Speaker 1: light source, right, and so that bubble is getting bigger

534
00:25:39,440 --> 00:25:42,600
Speaker 1: and bigger until it hits something. But that bubble kind

535
00:25:42,600 --> 00:25:45,960
Speaker 1: of has a location, right, It's on the surface of

536
00:25:45,960 --> 00:25:47,879
Speaker 1: that bubble. So how can it be on the surface

537
00:25:47,880 --> 00:25:50,000
Speaker 1: of the bubble and also everywhere all at once?

538
00:25:50,119 --> 00:25:53,439
Speaker 2: Yeah, great question. The answer is in the uncertainty of

539
00:25:53,480 --> 00:25:57,520
Speaker 2: its energy. If a star really could produce photons of

540
00:25:57,600 --> 00:26:01,120
Speaker 2: exactly one energy, then they would be everywhere all at once.

541
00:26:01,440 --> 00:26:04,720
Speaker 2: But that's totally unphysical. You can't have something everywhere in

542
00:26:04,760 --> 00:26:07,560
Speaker 2: the universe all at once, right, That like violates all

543
00:26:07,600 --> 00:26:10,760
Speaker 2: sorts of principles of relativity. Quantum mechanics and relativity sometimes

544
00:26:10,800 --> 00:26:12,760
Speaker 2: take a little bit of conceptual glue to stick together.

545
00:26:13,280 --> 00:26:15,600
Speaker 2: The way to resolve it is to realize, well, there

546
00:26:15,680 --> 00:26:18,520
Speaker 2: are no such photons in the universe. Nothing is actually

547
00:26:18,560 --> 00:26:22,960
Speaker 2: made with that exact, super specific energy. In reality, photons

548
00:26:22,960 --> 00:26:25,720
Speaker 2: always have an uncertainty in their energy. A star is

549
00:26:25,800 --> 00:26:29,400
Speaker 2: never making exact energy photons. There's always a spread. Even

550
00:26:29,480 --> 00:26:32,199
Speaker 2: lasers that you think of as having one specific energy,

551
00:26:32,240 --> 00:26:35,879
Speaker 2: there's always an uncertainty. Even atoms when they're emitting photons

552
00:26:36,000 --> 00:26:39,280
Speaker 2: between energy levels, there's always a little bit of fuzziness there.

553
00:26:39,640 --> 00:26:42,679
Speaker 2: So there's an uncertainty in the photon's energy, and the

554
00:26:42,720 --> 00:26:45,600
Speaker 2: more uncertainty in the energy, the more constrained the photon

555
00:26:45,680 --> 00:26:48,080
Speaker 2: can be in space. So what's coming out of the

556
00:26:48,080 --> 00:26:51,200
Speaker 2: star is a ripple and it's localized in space because

557
00:26:51,240 --> 00:26:53,080
Speaker 2: there's an uncertainty in its energy.

558
00:26:53,320 --> 00:26:56,240
Speaker 1: Is the time at which it gets made also uncertain

559
00:26:56,760 --> 00:26:58,800
Speaker 1: or is that something we're allowed to know for sure,

560
00:26:59,440 --> 00:27:01,920
Speaker 1: because then you know, we know exactly when it was emanated,

561
00:27:01,960 --> 00:27:03,679
Speaker 1: and we know the speed of light never changes, and

562
00:27:03,760 --> 00:27:05,919
Speaker 1: we know sort of exactly where that bubble is.

563
00:27:06,320 --> 00:27:09,280
Speaker 2: Yeah, there's a Heisenberg and certainty relationship between uncertainty and

564
00:27:09,359 --> 00:27:12,040
Speaker 2: energy and uncertainty in time. So now you can't know

565
00:27:12,119 --> 00:27:13,680
Speaker 2: that exactly either either.

566
00:27:14,160 --> 00:27:16,560
Speaker 1: No, so there's three things or they're all tied together.

567
00:27:16,640 --> 00:27:19,320
Speaker 2: They're all tied together. There's location and momentum, and then

568
00:27:19,359 --> 00:27:22,159
Speaker 2: there's energy and time. Those are two separate Heisenberg and

569
00:27:22,160 --> 00:27:25,640
Speaker 2: certainty relationships. But for a photon, momentum and energy are

570
00:27:25,720 --> 00:27:28,840
Speaker 2: the same thing. They're only different from massive particles, and

571
00:27:28,880 --> 00:27:31,440
Speaker 2: so they really are all three things tied together by

572
00:27:31,440 --> 00:27:34,359
Speaker 2: this fuzziness. And so it's the uncertainty. The fact that

573
00:27:34,359 --> 00:27:38,080
Speaker 2: we can never have pure single energy photons means we

574
00:27:38,119 --> 00:27:41,080
Speaker 2: always get these packets, these blobs. It's like, well, maybe

575
00:27:41,080 --> 00:27:43,480
Speaker 2: this photon is this energy, maybe it has that energy,

576
00:27:43,520 --> 00:27:46,760
Speaker 2: maybe it has this other energy. And that's what defines

577
00:27:46,840 --> 00:27:49,119
Speaker 2: the length of a photon. It's really a packet of

578
00:27:49,160 --> 00:27:52,239
Speaker 2: this uncertainty, and the amount of energy uncertainty in that

579
00:27:52,240 --> 00:27:55,760
Speaker 2: packet gives us the length of the uncertainty in its location.

580
00:27:56,240 --> 00:27:58,760
Speaker 1: Meaning like the bubble that emanates from the star or

581
00:27:58,840 --> 00:28:02,040
Speaker 1: light soars is not like a hard bubble, like a

582
00:28:02,240 --> 00:28:05,040
Speaker 1: real like soap bubble, but it's actually more like an

583
00:28:05,080 --> 00:28:06,320
Speaker 1: expanding fuzzy cloud.

584
00:28:06,440 --> 00:28:07,639
Speaker 2: Way I think about it, it's sort of like a

585
00:28:07,680 --> 00:28:10,480
Speaker 2: little wave packet. You got lots of frequencies together, they

586
00:28:10,560 --> 00:28:13,679
Speaker 2: add a subject, did they interfere positively and negatively to

587
00:28:13,720 --> 00:28:16,600
Speaker 2: give you this wave packet that's moving through space. For

588
00:28:16,640 --> 00:28:18,760
Speaker 2: those of you out there who know like signal analysis

589
00:28:18,840 --> 00:28:22,080
Speaker 2: or Fourier analysis, you know that, like a single momentum

590
00:28:22,119 --> 00:28:24,200
Speaker 2: corresponds to an infinite extent in space. But if you

591
00:28:24,240 --> 00:28:26,680
Speaker 2: add up a bunch of different momentum and different frequencies,

592
00:28:26,880 --> 00:28:29,240
Speaker 2: you can make any sort of shape you want in space.

593
00:28:29,640 --> 00:28:31,840
Speaker 1: Right, But then I feel like this, all this uncertainty

594
00:28:31,840 --> 00:28:34,159
Speaker 1: comes from the fact that we don't know when it

595
00:28:34,200 --> 00:28:36,800
Speaker 1: was made, this photon. We don't know how it was made.

596
00:28:36,880 --> 00:28:39,120
Speaker 1: We don't know how energy it had when it was made.

597
00:28:39,320 --> 00:28:41,239
Speaker 1: But once we detect it, we sort of do know

598
00:28:41,280 --> 00:28:43,520
Speaker 1: all these things. Right, Well, we never measure an energy

599
00:28:43,520 --> 00:28:46,520
Speaker 1: of a photon exactly right. You can never precisely measure

600
00:28:46,560 --> 00:28:48,080
Speaker 1: the energy of a photon. How do you measure it?

601
00:28:48,120 --> 00:28:51,040
Speaker 2: Anyway? You have it impact some device, and that device

602
00:28:51,120 --> 00:28:53,880
Speaker 2: has some mechanism inside of it, and you read that

603
00:28:53,960 --> 00:28:57,000
Speaker 2: number off. There's always uncertainty, not just because the mechanism

604
00:28:57,120 --> 00:28:59,680
Speaker 2: is something cheap you bought off Amazon. But because there

605
00:28:59,720 --> 00:29:03,040
Speaker 2: is an hair and quantum uncertainty in the measurement itself.

606
00:29:03,400 --> 00:29:05,600
Speaker 1: There's a little bit of uncertainty, sure, but like when

607
00:29:05,600 --> 00:29:07,440
Speaker 1: I'm looking at a hot dog, it doesn't suddenly turn

608
00:29:07,560 --> 00:29:10,240
Speaker 1: yellow or purple, or hopefully it doesn't turn yellow and

609
00:29:10,240 --> 00:29:11,280
Speaker 1: purple as I look at it.

610
00:29:11,320 --> 00:29:13,400
Speaker 2: The hot dog is not a laser, and it's not

611
00:29:13,440 --> 00:29:17,280
Speaker 2: an idealized laser. It's emitting a spread of colors, and

612
00:29:17,400 --> 00:29:19,840
Speaker 2: so every photon that comes out of that hot dog

613
00:29:19,880 --> 00:29:21,720
Speaker 2: has the possibility to be a little greener or a

614
00:29:21,720 --> 00:29:24,720
Speaker 2: little redder, or a little bluer. There's the fussiness in

615
00:29:24,800 --> 00:29:26,840
Speaker 2: every single photon that comes out of the hot dog.

616
00:29:27,760 --> 00:29:29,680
Speaker 1: But once I measure it, don't I know exactly what

617
00:29:29,800 --> 00:29:30,680
Speaker 1: frequency it had.

618
00:29:30,840 --> 00:29:33,000
Speaker 2: There's still an uncertainty when you measure it. But yeah,

619
00:29:33,000 --> 00:29:34,920
Speaker 2: it does collapse some of that uncertainty. I mean, you

620
00:29:34,960 --> 00:29:36,960
Speaker 2: see a blue photon, or you see a red photon,

621
00:29:37,040 --> 00:29:39,520
Speaker 2: or you see a green photon, but again still never

622
00:29:39,640 --> 00:29:40,480
Speaker 2: super precisely.

623
00:29:40,680 --> 00:29:43,840
Speaker 1: What if we had a perfect measurement device and we

624
00:29:43,880 --> 00:29:47,640
Speaker 1: can collapse it perfectly, would we know it's exact frequency.

625
00:29:48,040 --> 00:29:49,880
Speaker 2: I think such a device would have to be the

626
00:29:49,920 --> 00:29:51,920
Speaker 2: size of the universe, and so then you would know

627
00:29:51,960 --> 00:29:53,120
Speaker 2: nothing about where it was.

628
00:29:53,560 --> 00:29:54,360
Speaker 1: Can you explain that?

629
00:29:54,480 --> 00:29:56,840
Speaker 2: First of all, a device that measures anything exactly is

630
00:29:56,920 --> 00:29:59,880
Speaker 2: just impossible. Right, You can take the limit of something,

631
00:30:00,080 --> 00:30:02,600
Speaker 2: can start with like, what's the most precise measurement device

632
00:30:02,640 --> 00:30:04,440
Speaker 2: I can have, and then try to think about taking

633
00:30:04,440 --> 00:30:06,840
Speaker 2: the limit of it to perfect precision. Or to measure

634
00:30:06,880 --> 00:30:09,200
Speaker 2: something very precisely that has a lot of energy, you

635
00:30:09,240 --> 00:30:11,160
Speaker 2: need to have an object which you can interact with

636
00:30:11,200 --> 00:30:14,280
Speaker 2: photons of very different wavelengths. Right, wavelengths can be very

637
00:30:14,320 --> 00:30:17,160
Speaker 2: very short for very high energy, or very very large

638
00:30:17,200 --> 00:30:19,760
Speaker 2: for very low energy, and so measuring things that are

639
00:30:19,840 --> 00:30:22,840
Speaker 2: very very large requires large objects. Like you want to

640
00:30:22,880 --> 00:30:26,520
Speaker 2: receive radio waves, you need a very big antenna. You

641
00:30:26,520 --> 00:30:29,840
Speaker 2: want to receive microwaves, you need very small antennas. So

642
00:30:29,920 --> 00:30:32,440
Speaker 2: you want to measure something super precisely that can be

643
00:30:32,480 --> 00:30:35,320
Speaker 2: of any wavelength, you're going to need essentially an antenna

644
00:30:35,400 --> 00:30:36,480
Speaker 2: the size of the universe.

645
00:30:36,920 --> 00:30:39,560
Speaker 1: Oh boy, that's a that would be a very big

646
00:30:39,640 --> 00:30:40,040
Speaker 1: hot dog.

647
00:30:40,920 --> 00:30:42,600
Speaker 2: It costs more than a hot dog, all right, But.

648
00:30:42,600 --> 00:30:45,080
Speaker 1: Maybe let's give up on perfection and say that you know,

649
00:30:45,160 --> 00:30:48,400
Speaker 1: I measure a photon coming for my hot dog, and

650
00:30:48,440 --> 00:30:51,440
Speaker 1: I see that it's red plus or minus point one, hurts.

651
00:30:51,680 --> 00:30:54,480
Speaker 1: That's a pretty good measurement of its wavelength. No, we

652
00:30:54,720 --> 00:30:55,960
Speaker 1: can get to that point, right.

653
00:30:55,960 --> 00:30:59,080
Speaker 2: Yeah, you can make fairly precise measurements of individual photons. Yes,

654
00:30:59,280 --> 00:31:03,520
Speaker 2: you can also sources of photons that are fairly pure,

655
00:31:03,560 --> 00:31:06,440
Speaker 2: that are very tight bands of energy ranges. Yeah.

656
00:31:06,480 --> 00:31:08,800
Speaker 1: So then if I know the wavelength of the photon,

657
00:31:08,920 --> 00:31:11,120
Speaker 1: doesn't that give me a sense of how long it is?

658
00:31:11,560 --> 00:31:13,440
Speaker 2: If you know the wavelength of the photon and you

659
00:31:13,520 --> 00:31:16,800
Speaker 2: know the uncertainty in that wavelength, then yes, that defines

660
00:31:16,840 --> 00:31:20,320
Speaker 2: the length of this wave packet, all these possible photons

661
00:31:20,360 --> 00:31:23,080
Speaker 2: that are flying through space together. It's a little unsatisfying

662
00:31:23,120 --> 00:31:25,960
Speaker 2: as an answer because it's not something inherent to the photon.

663
00:31:26,440 --> 00:31:28,680
Speaker 2: It's like you got a bunch of these blobs all

664
00:31:28,680 --> 00:31:31,760
Speaker 2: moving together through the universe. The answer how long is

665
00:31:31,800 --> 00:31:35,000
Speaker 2: the photon depends sort of like on your uncertainty in

666
00:31:35,040 --> 00:31:37,400
Speaker 2: your knowledge of its energy. So I think it's accurate

667
00:31:37,400 --> 00:31:39,080
Speaker 2: from a quantum mechanical point of view, but it's very

668
00:31:39,120 --> 00:31:42,080
Speaker 2: unsatisfying from a philosophical point of view because it feels

669
00:31:42,120 --> 00:31:45,320
Speaker 2: like the photon should have a length that's just inherent

670
00:31:45,400 --> 00:31:47,840
Speaker 2: to it. It shouldn't depend on your measurement of it

671
00:31:48,240 --> 00:31:49,280
Speaker 2: or your knowledge of it.

672
00:31:49,520 --> 00:31:52,200
Speaker 1: But it doesn't sort of depend on my knowledge or

673
00:31:52,320 --> 00:31:54,120
Speaker 1: measurement of it, right, Like if I measured it and

674
00:31:54,160 --> 00:31:56,400
Speaker 1: I measured the red pleasure minus point when it hurts,

675
00:31:56,520 --> 00:31:58,480
Speaker 1: and somebody else measured would have measured it, they would

676
00:31:58,520 --> 00:31:59,920
Speaker 1: have probably gone the same result.

677
00:32:00,120 --> 00:32:02,920
Speaker 2: Right, Yeah, it doesn't depend on your particular knowledge of it.

678
00:32:02,920 --> 00:32:05,640
Speaker 2: There is an inherent uncertainty in it because it's a

679
00:32:05,720 --> 00:32:08,600
Speaker 2: quantum state, and to me that's a little bit unsatisfying.

680
00:32:08,760 --> 00:32:11,040
Speaker 2: The idea that it doesn't have a fixed length or

681
00:32:11,040 --> 00:32:14,040
Speaker 2: that it's length somehow depends on that uncertainty. To answer

682
00:32:14,080 --> 00:32:16,960
Speaker 2: your specific question. If there's uncertainty, it means that no

683
00:32:17,080 --> 00:32:19,680
Speaker 2: two people would make exactly the same measurement. They'd be

684
00:32:19,680 --> 00:32:22,800
Speaker 2: probably consistent, you know, within the uncertainties, but they wouldn't

685
00:32:22,840 --> 00:32:24,040
Speaker 2: get exactly the same.

686
00:32:23,840 --> 00:32:28,040
Speaker 1: Answer, right Right. We would all see it as vapor hotdog, right,

687
00:32:28,080 --> 00:32:30,400
Speaker 1: And so couldn't you. I mean, I know we're not

688
00:32:30,520 --> 00:32:32,880
Speaker 1: we can ever get super preciped, but we can probably

689
00:32:32,880 --> 00:32:35,120
Speaker 1: say you and I can both agree that yeah, that's

690
00:32:35,240 --> 00:32:37,400
Speaker 1: vapor hotdog and not miss the hot dog.

691
00:32:37,800 --> 00:32:40,200
Speaker 2: Yeah, And I'm not saying photons don't have a length.

692
00:32:40,280 --> 00:32:42,280
Speaker 2: I'm just saying that the length depends not just on

693
00:32:42,360 --> 00:32:45,520
Speaker 2: the wavelength of light, but on the uncertainty on the wavelength,

694
00:32:45,560 --> 00:32:47,280
Speaker 2: because in the end, they're quantum objects.

695
00:32:47,640 --> 00:32:49,680
Speaker 1: Right, So then can we answer the question of how

696
00:32:49,720 --> 00:32:52,800
Speaker 1: long a photon is or was? Or is it that

697
00:32:52,840 --> 00:32:55,280
Speaker 1: we can only answer what the length of a pooton was.

698
00:32:55,640 --> 00:32:58,040
Speaker 2: We can answer the question if you know the energy

699
00:32:58,160 --> 00:33:02,240
Speaker 2: and the uncertainty on that energy that determines the length

700
00:33:02,280 --> 00:33:04,320
Speaker 2: of the photon in this sense of length.

701
00:33:04,560 --> 00:33:09,560
Speaker 1: So that's good, right, possible? Yeah, are you saying it's impossible.

702
00:33:09,600 --> 00:33:10,880
Speaker 2: No, No, I'm saying it's possible.

703
00:33:11,000 --> 00:33:13,720
Speaker 1: All right, So then that's the quantum field theory version

704
00:33:13,760 --> 00:33:16,240
Speaker 1: of a photon. You said that how long a ploton

705
00:33:16,320 --> 00:33:18,800
Speaker 1: is depends on how you look at it. So then

706
00:33:18,920 --> 00:33:21,719
Speaker 1: if we assume light is a particle, can we measure

707
00:33:21,960 --> 00:33:23,160
Speaker 1: the length of that particle?

708
00:33:23,240 --> 00:33:25,239
Speaker 2: Yeah, The answer does depend a little bit on how

709
00:33:25,280 --> 00:33:27,160
Speaker 2: you look at it, because in some cases you don't

710
00:33:27,200 --> 00:33:29,640
Speaker 2: care about the length of photon. You don't care about

711
00:33:29,680 --> 00:33:31,680
Speaker 2: these details, and you don't care about the size of

712
00:33:31,720 --> 00:33:34,360
Speaker 2: anything that's really really small. So you could just treat

713
00:33:34,400 --> 00:33:37,080
Speaker 2: them as zero point particles. And we talk on the

714
00:33:37,120 --> 00:33:39,520
Speaker 2: podcast a lot about how like electrons have no size

715
00:33:39,560 --> 00:33:42,000
Speaker 2: and quarks have no size, And the answer to that

716
00:33:42,040 --> 00:33:44,120
Speaker 2: really is they have no size that we measure or

717
00:33:44,160 --> 00:33:46,600
Speaker 2: in some cases that we care about, and so we

718
00:33:46,640 --> 00:33:49,120
Speaker 2: can treat them as if they're zero point particles with

719
00:33:49,280 --> 00:33:51,840
Speaker 2: no length to them. For some problems where it doesn't

720
00:33:51,840 --> 00:33:53,959
Speaker 2: really matter if they have length, you know, like when

721
00:33:54,000 --> 00:33:56,000
Speaker 2: they're hitting a screen, we didn't really care how long

722
00:33:56,000 --> 00:33:58,120
Speaker 2: it took to hit the screen or what their extent

723
00:33:58,200 --> 00:33:59,720
Speaker 2: was as they were flying through space. We can just

724
00:33:59,760 --> 00:34:02,840
Speaker 2: treat them as if they were tiny, zero point particles,

725
00:34:03,000 --> 00:34:05,160
Speaker 2: And so that picture is useful for answering some kinds

726
00:34:05,240 --> 00:34:07,480
Speaker 2: of questions, just the same way we can think about

727
00:34:07,560 --> 00:34:10,000
Speaker 2: classical waves moving through space.

728
00:34:10,239 --> 00:34:12,279
Speaker 1: Well, I feel like it's sort of useful, maybe, I

729
00:34:12,360 --> 00:34:16,080
Speaker 1: wonder in some applications, like for example, let's say photons

730
00:34:16,120 --> 00:34:19,120
Speaker 1: are super duper long, they're the size of a planet

731
00:34:19,160 --> 00:34:23,719
Speaker 1: sized hotdog. Then when that photon hits me, it's going

732
00:34:23,760 --> 00:34:27,080
Speaker 1: to take a long time, you know, minute for me

733
00:34:27,160 --> 00:34:29,840
Speaker 1: to feel the photon all the way, as opposed to

734
00:34:30,320 --> 00:34:33,280
Speaker 1: if a photon is just an infinitely small point particle,

735
00:34:33,400 --> 00:34:36,440
Speaker 1: then I'm going to feel the photon instantly. So is

736
00:34:36,480 --> 00:34:39,360
Speaker 1: there sort of a time at which I get to

737
00:34:39,440 --> 00:34:42,239
Speaker 1: feel photons or is it relevant or what are the

738
00:34:42,280 --> 00:34:43,279
Speaker 1: hot dog dynamics here?

739
00:34:43,400 --> 00:34:45,680
Speaker 2: Yeah, so that's a great question, and to answer that question,

740
00:34:45,760 --> 00:34:48,000
Speaker 2: you definitely need to use the quantum field theory version

741
00:34:48,000 --> 00:34:49,600
Speaker 2: of a hot dog. You need to think about the

742
00:34:49,600 --> 00:34:53,400
Speaker 2: probability of photon having various wavelengths and those wavelengths overlapping

743
00:34:53,440 --> 00:34:56,400
Speaker 2: with you. When that probability wave packet overlaps with you,

744
00:34:56,440 --> 00:34:59,240
Speaker 2: and when it doesn't overlap with you, when it does collapse,

745
00:34:59,239 --> 00:35:02,319
Speaker 2: though it collapses instantly across the entire photon, you can't

746
00:35:02,320 --> 00:35:04,879
Speaker 2: feel like part of a photon. There is no part

747
00:35:04,920 --> 00:35:07,440
Speaker 2: of a photon, right, Photons are quantized.

748
00:35:07,000 --> 00:35:09,960
Speaker 1: Like when I feel a photon, it's instantaneous, is what

749
00:35:10,000 --> 00:35:10,359
Speaker 1: you're saying?

750
00:35:10,440 --> 00:35:13,520
Speaker 2: Yeah, you feel the whole photon or no photons exactly

751
00:35:13,680 --> 00:35:14,960
Speaker 2: or so or seven photons.

752
00:35:15,160 --> 00:35:17,120
Speaker 1: What if it has like super duper big waves like

753
00:35:17,120 --> 00:35:21,000
Speaker 1: we've talked about light waves having a wavelength the size

754
00:35:21,040 --> 00:35:24,120
Speaker 1: of a galaxy for example, Like we feel those instantly

755
00:35:24,280 --> 00:35:25,880
Speaker 1: or do we need to wait a long time to

756
00:35:25,920 --> 00:35:26,399
Speaker 1: feel them?

757
00:35:26,560 --> 00:35:29,120
Speaker 2: Yeah? You either feel them or you don't. Right, there's

758
00:35:29,160 --> 00:35:33,200
Speaker 2: no time at which you're like crewing a photon, right.

759
00:35:33,040 --> 00:35:35,120
Speaker 1: But the ripple of it isn't the ripple of it

760
00:35:35,200 --> 00:35:37,279
Speaker 1: in space long to or what?

761
00:35:37,520 --> 00:35:40,920
Speaker 2: Yeah, so photons could be really really long, right, if

762
00:35:40,960 --> 00:35:43,680
Speaker 2: you have a photon with really long wavelengths and really

763
00:35:43,719 --> 00:35:47,839
Speaker 2: large uncertainty, those photons could be the size of a galaxy, absolutely,

764
00:35:48,239 --> 00:35:51,560
Speaker 2: and that photon could interact with something within the galaxy. Right,

765
00:35:51,560 --> 00:35:54,000
Speaker 2: But then the whole photon collapses all at once, just

766
00:35:54,040 --> 00:35:55,840
Speaker 2: the same way that a pair of entangled particles you

767
00:35:55,880 --> 00:35:58,719
Speaker 2: shoot off in opposite directions, they're really still part of

768
00:35:58,800 --> 00:36:01,640
Speaker 2: one big quantum state. You measure one on one side

769
00:36:01,680 --> 00:36:04,719
Speaker 2: of the galaxy, the whole quantum state collapses at once,

770
00:36:04,760 --> 00:36:08,080
Speaker 2: because it's really just one quantum state. Same way for

771
00:36:08,120 --> 00:36:11,719
Speaker 2: this galaxy size hot dog size photon. If it's really

772
00:36:11,760 --> 00:36:14,239
Speaker 2: as big as the galaxy, If it interacts anywhere, then

773
00:36:14,280 --> 00:36:16,200
Speaker 2: the whole quantum state collapses at once.

774
00:36:16,560 --> 00:36:20,359
Speaker 1: M So, like you can think of it as having

775
00:36:20,400 --> 00:36:22,439
Speaker 1: a giant photon the size of a galaxy. But once

776
00:36:22,480 --> 00:36:25,200
Speaker 1: I catch it, it's really just a little tiny point particle.

777
00:36:25,440 --> 00:36:27,840
Speaker 2: Yeah, exactly. It interacts in that one spot and you

778
00:36:27,920 --> 00:36:31,040
Speaker 2: might think, hold on a second, doesn't this violate special relativity?

779
00:36:31,080 --> 00:36:33,680
Speaker 2: And it feels like, you know, that might allow you

780
00:36:33,719 --> 00:36:36,239
Speaker 2: to send messages faster than time. And there is a

781
00:36:36,239 --> 00:36:40,480
Speaker 2: real subtlety there with how quantum theory and relativity interact.

782
00:36:40,640 --> 00:36:42,759
Speaker 2: We talked about in the podcast. It's the reason why

783
00:36:42,800 --> 00:36:46,360
Speaker 2: we have anti particles. Antiparticles patch all this up with

784
00:36:46,480 --> 00:36:49,239
Speaker 2: all these negative probabilities and make sure that everything is

785
00:36:49,239 --> 00:36:52,000
Speaker 2: following all the rules. Check out our episode on why

786
00:36:52,080 --> 00:36:55,040
Speaker 2: quantum mechanics and special relativity require antiparticles.

787
00:36:55,120 --> 00:36:57,720
Speaker 1: Well, I feel like you're kind of making a judgment

788
00:36:57,880 --> 00:37:01,200
Speaker 1: on the particle view of life. You're saying it's not

789
00:37:01,280 --> 00:37:05,480
Speaker 1: really a particle, or you ultimately have to kind of

790
00:37:05,520 --> 00:37:08,520
Speaker 1: go back to quantum theory to talk about light. We

791
00:37:08,560 --> 00:37:10,680
Speaker 1: can't stay in the particle view at for very long.

792
00:37:11,320 --> 00:37:14,919
Speaker 2: I'm definitely using this field picture here, thinking about light

793
00:37:15,040 --> 00:37:18,600
Speaker 2: as ripples in electromagnetic field, and that I think is

794
00:37:18,640 --> 00:37:21,440
Speaker 2: the most mainstream view. But there's definitely a chunk of

795
00:37:21,640 --> 00:37:24,440
Speaker 2: particle theorists who think in the particle picture, and you

796
00:37:24,480 --> 00:37:27,960
Speaker 2: absolutely can you can replace the field with an infinite

797
00:37:28,040 --> 00:37:31,840
Speaker 2: number of virtual particles and do all the same calculations

798
00:37:31,880 --> 00:37:34,000
Speaker 2: and it all works. So what I've described is the

799
00:37:34,000 --> 00:37:37,600
Speaker 2: field picture of light as a ripple in this electromagnetic field.

800
00:37:37,680 --> 00:37:39,880
Speaker 2: You can also think about these probabilities in terms of

801
00:37:39,920 --> 00:37:43,200
Speaker 2: like these virtual particles, which are conceptually kind of slippery

802
00:37:43,239 --> 00:37:46,120
Speaker 2: because they're not really particles or really just probabilities. But

803
00:37:46,160 --> 00:37:48,239
Speaker 2: you can think about all these kind of interactions and

804
00:37:48,280 --> 00:37:51,480
Speaker 2: these transmissions in terms of an infinite number of virtual particles,

805
00:37:51,600 --> 00:37:53,760
Speaker 2: if you like. Though I think it's a lot more awkward,

806
00:37:54,000 --> 00:37:55,000
Speaker 2: especially in this case.

807
00:37:55,239 --> 00:37:57,480
Speaker 1: Well awkward is a relative tern I know they might

808
00:37:57,480 --> 00:37:58,480
Speaker 1: say the same thing about you.

809
00:37:58,920 --> 00:38:02,399
Speaker 2: Yeah, absolutely, and a little bit subjective. Mathematically, both pictures work,

810
00:38:02,440 --> 00:38:04,960
Speaker 2: so I'm trying not to make a judgment on what

811
00:38:05,080 --> 00:38:08,040
Speaker 2: is the best picture of the quantum universe. There's a

812
00:38:08,080 --> 00:38:10,239
Speaker 2: particle people and the fields people, and both of them

813
00:38:10,440 --> 00:38:13,640
Speaker 2: have strong cases. Conceptually, For me, the fields picture is

814
00:38:13,640 --> 00:38:15,600
Speaker 2: more intuitive, though that doesn't mean that it's right.

815
00:38:16,120 --> 00:38:19,200
Speaker 1: Right. So then let's say we replace you, Daniel. We

816
00:38:19,239 --> 00:38:22,960
Speaker 1: call this podcast Mark and Jorge explain the universe, and

817
00:38:23,000 --> 00:38:26,319
Speaker 1: Mark happens to be a particle person that sees the

818
00:38:26,320 --> 00:38:28,960
Speaker 1: world as particles. How would they answer the question how

819
00:38:29,000 --> 00:38:29,920
Speaker 1: long is a particle?

820
00:38:30,120 --> 00:38:32,680
Speaker 2: Even in the particle picture of the universe where there

821
00:38:32,680 --> 00:38:35,080
Speaker 2: are no fields, there's just an infinite number of real

822
00:38:35,120 --> 00:38:38,680
Speaker 2: particles and an infinite number of virtual particles communicating between them.

823
00:38:38,920 --> 00:38:42,120
Speaker 2: There are still probabilities, you still have wave functions about

824
00:38:42,120 --> 00:38:45,600
Speaker 2: where these particles are, and uncertainties on where the particles

825
00:38:45,600 --> 00:38:47,920
Speaker 2: are and how much energy they have. So in the end,

826
00:38:47,960 --> 00:38:50,680
Speaker 2: the answer is very much the same. Right. A photon,

827
00:38:50,719 --> 00:38:52,600
Speaker 2: even if you think about it as a particle, has

828
00:38:52,600 --> 00:38:56,279
Speaker 2: an uncertainty in its location. A photon is infinitely well known,

829
00:38:56,320 --> 00:38:59,640
Speaker 2: but still have an infinite uncertainty in its location. And

830
00:39:00,040 --> 00:39:01,720
Speaker 2: so even if you think about in terms of particles,

831
00:39:01,760 --> 00:39:04,200
Speaker 2: you get the same answer. It's either a packet of

832
00:39:04,280 --> 00:39:07,359
Speaker 2: waves moving through the universe with a range of frequencies,

833
00:39:07,719 --> 00:39:10,360
Speaker 2: or it's a packet of possible particles moving through the

834
00:39:10,440 --> 00:39:12,480
Speaker 2: universe with a range of possible energies.

835
00:39:12,760 --> 00:39:14,879
Speaker 1: All right, thank you Mary for answering that question. Now,

836
00:39:15,480 --> 00:39:17,680
Speaker 1: I think what you're saying is that even if you

837
00:39:17,719 --> 00:39:21,320
Speaker 1: look at the lightest particles, a particle is a point particle,

838
00:39:21,520 --> 00:39:24,200
Speaker 1: so itself, it doesn't have any length. So it kind

839
00:39:24,200 --> 00:39:25,759
Speaker 1: of doesn't make sense to talk about the length of

840
00:39:25,800 --> 00:39:29,360
Speaker 1: a photon. But these point particles have a certain fuzziness

841
00:39:29,440 --> 00:39:31,200
Speaker 1: about where they can be in the universe, and maybe

842
00:39:31,200 --> 00:39:33,920
Speaker 1: you can talk about the length of that fuzzy cloud

843
00:39:33,920 --> 00:39:38,000
Speaker 1: of where it could be, but ultimately you kind of

844
00:39:38,000 --> 00:39:41,040
Speaker 1: have to make a call about where where you draw

845
00:39:41,120 --> 00:39:44,799
Speaker 1: those boundaries, Like these fuzzy clouds don't have a hard

846
00:39:44,880 --> 00:39:47,280
Speaker 1: edge to them, the kind of fuzzy out to infinity,

847
00:39:47,880 --> 00:39:50,200
Speaker 1: and so it's up to you to say, this is

848
00:39:50,200 --> 00:39:51,719
Speaker 1: what I would call the photon, this is what would

849
00:39:51,760 --> 00:39:52,960
Speaker 1: not call the photon.

850
00:39:52,760 --> 00:39:55,399
Speaker 2: Exactly, And the pure concept of a single photon isn't

851
00:39:55,400 --> 00:39:58,000
Speaker 2: really helpful number one because they never exist in the universe,

852
00:39:58,000 --> 00:40:01,000
Speaker 2: and number two because they have infinite uncertainty in their

853
00:40:01,080 --> 00:40:03,560
Speaker 2: location and so they're sort of everywhere.

854
00:40:03,719 --> 00:40:07,879
Speaker 1: Cool, Well, I like this new podcast host Mary. Does

855
00:40:07,920 --> 00:40:10,200
Speaker 1: Mary like white chocolate? Then, because she's.

856
00:40:10,000 --> 00:40:12,959
Speaker 2: The of you, No, she agrees with me and everything else?

857
00:40:14,200 --> 00:40:18,719
Speaker 1: Right, all right, Well, let's talk about how you might

858
00:40:18,800 --> 00:40:21,680
Speaker 1: actually measure what you might call the length of a photon,

859
00:40:21,840 --> 00:40:25,200
Speaker 1: or not measure it, or maybe it's impossible. So let's

860
00:40:25,239 --> 00:40:27,880
Speaker 1: dig into that question. But first let's take one more break.

861
00:40:40,480 --> 00:40:42,400
Speaker 1: All right, we're talking about the length of a photon,

862
00:40:42,520 --> 00:40:47,320
Speaker 1: and now is it Daniel's backwards. It's still Mary.

863
00:40:49,040 --> 00:40:49,920
Speaker 2: Let's go back to Dan.

864
00:40:52,160 --> 00:40:55,879
Speaker 1: All right, we've sort of concluded that, you know, light

865
00:40:55,960 --> 00:40:58,200
Speaker 1: is a fuzzy quantum thing, so to talk about its

866
00:40:58,280 --> 00:41:00,880
Speaker 1: length kind of doesn't make sense. But there's sort of

867
00:41:00,880 --> 00:41:02,640
Speaker 1: the other aspect of it, which is what I was

868
00:41:02,800 --> 00:41:04,440
Speaker 1: trying to get at, which is like, when you measure

869
00:41:04,440 --> 00:41:07,160
Speaker 1: a photon, maybe you can measure its length sort of

870
00:41:07,239 --> 00:41:09,319
Speaker 1: because maybe it depends on how big your eyeball is

871
00:41:09,520 --> 00:41:12,200
Speaker 1: or how you know, how long you're there waiting for

872
00:41:12,239 --> 00:41:13,960
Speaker 1: the hot dog to hit you. So let's talk about

873
00:41:13,960 --> 00:41:16,480
Speaker 1: measuring how do you measure a photon and how does

874
00:41:16,520 --> 00:41:17,680
Speaker 1: it change the length of it?

875
00:41:17,880 --> 00:41:20,160
Speaker 2: Yeah, this is really fun. I spent some time thinking

876
00:41:20,200 --> 00:41:23,280
Speaker 2: about this and starting with how you measure the size

877
00:41:23,320 --> 00:41:25,640
Speaker 2: of other particles. It's a little bit easier to think

878
00:41:25,680 --> 00:41:28,640
Speaker 2: about like measuring the size of a proton, because we've

879
00:41:28,680 --> 00:41:31,680
Speaker 2: done that, or try to measure the size of the electron,

880
00:41:31,719 --> 00:41:33,080
Speaker 2: because we've tried to do that.

881
00:41:33,320 --> 00:41:35,400
Speaker 1: Well, we have measured the length of a proton.

882
00:41:35,520 --> 00:41:37,880
Speaker 2: We have measured the width of a proton. Yes, absolutely

883
00:41:37,880 --> 00:41:39,960
Speaker 2: we know something about the size of a proton.

884
00:41:40,120 --> 00:41:42,319
Speaker 1: Wait, wait, I thought we just concluded that you can't

885
00:41:42,360 --> 00:41:43,640
Speaker 1: do that with quantum particles.

886
00:41:43,920 --> 00:41:46,680
Speaker 2: We decided you can. But protons are not like fundamental

887
00:41:46,719 --> 00:41:49,759
Speaker 2: objects in the universe, right, So really we're talking about

888
00:41:49,800 --> 00:41:51,759
Speaker 2: like a bound state of quarks and how close do

889
00:41:51,800 --> 00:41:52,839
Speaker 2: they stay to each other?

890
00:41:52,960 --> 00:41:55,359
Speaker 1: But even that has a sort of an uncertainty that

891
00:41:55,440 --> 00:41:57,600
Speaker 1: spills out to infinity, doesn't it. So where do you

892
00:41:57,640 --> 00:42:00,480
Speaker 1: define the bounds of a proton?

893
00:42:00,600 --> 00:42:02,120
Speaker 2: Yeah, it's a little bit fuzzy, and you have to

894
00:42:02,160 --> 00:42:04,520
Speaker 2: do a little bit of mental gymnastics and come up

895
00:42:04,560 --> 00:42:07,840
Speaker 2: with a concept of size that makes sense for these particles.

896
00:42:07,840 --> 00:42:10,240
Speaker 2: You have to think about like what can I actually

897
00:42:10,280 --> 00:42:12,880
Speaker 2: measure and what number does that give me? And is

898
00:42:12,920 --> 00:42:15,320
Speaker 2: that really measuring the size of the object.

899
00:42:15,600 --> 00:42:18,080
Speaker 1: All right, let me do some mental stretching here before

900
00:42:18,120 --> 00:42:20,960
Speaker 1: I do some mental gymnastics. Well, what do you mean?

901
00:42:21,239 --> 00:42:23,839
Speaker 1: So when you say the side, because you just said

902
00:42:23,920 --> 00:42:26,879
Speaker 1: the size of a proton pretty decisively, would then as

903
00:42:26,880 --> 00:42:29,839
Speaker 1: a particle physicist, what do you define as the edge

904
00:42:29,840 --> 00:42:30,440
Speaker 1: of a proton?

905
00:42:30,520 --> 00:42:33,120
Speaker 2: Yeah? So I will be totally upfront here. The physics

906
00:42:33,120 --> 00:42:36,759
Speaker 2: has redefined size and then answered the question. What we

907
00:42:36,840 --> 00:42:38,840
Speaker 2: really mean is that we do a specific kind of

908
00:42:38,840 --> 00:42:42,799
Speaker 2: experiment where we bounce stuff off the proton, and we

909
00:42:43,040 --> 00:42:46,600
Speaker 2: notice how that changes as we scan across a proton. So,

910
00:42:46,640 --> 00:42:49,440
Speaker 2: for example, you shoot electrons at the proton and they

911
00:42:49,440 --> 00:42:51,359
Speaker 2: mostly go through, and then you shoot them a little

912
00:42:51,360 --> 00:42:53,399
Speaker 2: bit to the right and oops, now they're bouncing back,

913
00:42:53,440 --> 00:42:56,400
Speaker 2: or now they're exploding the proton. And as you keep going,

914
00:42:56,480 --> 00:42:59,160
Speaker 2: you discover that as you sweep your beam over past

915
00:42:59,200 --> 00:43:01,520
Speaker 2: the other side of the proton, then now it's missing

916
00:43:01,600 --> 00:43:04,480
Speaker 2: the proton again. So there's like a size of the

917
00:43:04,480 --> 00:43:06,840
Speaker 2: proton there in the sense of like how it reacts

918
00:43:06,880 --> 00:43:10,719
Speaker 2: to the beam and electrons that you're sweeping over it.

919
00:43:10,719 --> 00:43:13,359
Speaker 1: It's sort of like searching for a stud on your.

920
00:43:13,280 --> 00:43:16,600
Speaker 2: Wall, right, Yeah, exactly. It's a little bit philosophical to

921
00:43:16,600 --> 00:43:19,440
Speaker 2: interpret this as size, because what do you mean anyway

922
00:43:19,480 --> 00:43:21,719
Speaker 2: by the size of a proton. A proton is an

923
00:43:21,800 --> 00:43:23,920
Speaker 2: easier thing to talk about than a photon, because at

924
00:43:24,000 --> 00:43:26,160
Speaker 2: least a proton has mass. You can like hold one,

925
00:43:26,440 --> 00:43:28,560
Speaker 2: you can capture one, you can say this is the

926
00:43:28,560 --> 00:43:31,160
Speaker 2: one I'm talking about. Photons are much harder, and we'll

927
00:43:31,160 --> 00:43:32,480
Speaker 2: talk in a minute about how you might be able

928
00:43:32,480 --> 00:43:34,239
Speaker 2: to measure their size. But this is the kind of

929
00:43:34,320 --> 00:43:36,399
Speaker 2: thing we do for a proton and This is one way,

930
00:43:36,440 --> 00:43:39,120
Speaker 2: for example, that we discovered that the atom had a

931
00:43:39,160 --> 00:43:43,000
Speaker 2: proton inside of it. Right. Rutherford's original experiment was basically this,

932
00:43:43,239 --> 00:43:45,480
Speaker 2: You shut alpha particles at gold foils and notice that

933
00:43:45,520 --> 00:43:47,719
Speaker 2: they bounce back sometimes and not other times. And he

934
00:43:47,840 --> 00:43:50,319
Speaker 2: used this to see like, oh, there's like hard little

935
00:43:50,360 --> 00:43:53,440
Speaker 2: nuggets inside the gold foil, and those were the nuclei.

936
00:43:53,760 --> 00:43:55,440
Speaker 2: And you can do the same kind of thing to

937
00:43:55,440 --> 00:43:57,200
Speaker 2: see the size or a proton. You can also do

938
00:43:57,239 --> 00:43:59,440
Speaker 2: the same kind of thing to see inside a proton,

939
00:43:59,480 --> 00:44:01,560
Speaker 2: to see like how often is it bouncing off of

940
00:44:01,560 --> 00:44:03,480
Speaker 2: a quark that's inside the proton?

941
00:44:03,840 --> 00:44:05,920
Speaker 1: Right, But like you said, it's sort of a fuzzy boundary,

942
00:44:05,960 --> 00:44:08,520
Speaker 1: isn't it. Like as you're scanning where the proton is

943
00:44:08,520 --> 00:44:11,400
Speaker 1: by shooting electrons at it, at some point like sometimes

944
00:44:11,440 --> 00:44:13,360
Speaker 1: it'll hit, sometimes it won't, even though you're shooting in

945
00:44:13,400 --> 00:44:16,520
Speaker 1: the same exact direction, And as you scan through the right,

946
00:44:16,560 --> 00:44:19,600
Speaker 1: for example, the frequency at which it might glance off

947
00:44:19,640 --> 00:44:22,880
Speaker 1: of the proton changes. So there's a bit of fuzziness.

948
00:44:22,880 --> 00:44:24,399
Speaker 1: So when do you make the call like okay, that's

949
00:44:24,400 --> 00:44:26,319
Speaker 1: the edge of the proton, or do you.

950
00:44:26,480 --> 00:44:28,560
Speaker 2: Know you're exactly right? There's a little bit of fuzziness there,

951
00:44:28,560 --> 00:44:31,279
Speaker 2: Like if you did this experiment with billiard balls, right,

952
00:44:31,360 --> 00:44:33,279
Speaker 2: there'd be a moment when they come into contact and

953
00:44:33,320 --> 00:44:35,919
Speaker 2: then a moment when they don't, and there's a precision there,

954
00:44:36,239 --> 00:44:38,920
Speaker 2: and we don't have the same thing with protons. There's

955
00:44:39,040 --> 00:44:41,360
Speaker 2: some point at which you shoot the electron and sometimes

956
00:44:41,360 --> 00:44:44,040
Speaker 2: it bounces back and sometimes it passes through, and so

957
00:44:44,120 --> 00:44:46,600
Speaker 2: like is that the edge of the proton, And so

958
00:44:46,640 --> 00:44:48,920
Speaker 2: we just make a sort of mathematical definition. We define

959
00:44:48,960 --> 00:44:51,319
Speaker 2: the width of this distribution, and we say that with

960
00:44:51,520 --> 00:44:54,680
Speaker 2: this distribution tells us the size of the proton.

961
00:44:54,440 --> 00:44:57,280
Speaker 1: Meaning like the width of a proton is the width

962
00:44:57,320 --> 00:45:00,520
Speaker 1: at which if you aim at an electron added beyond

963
00:45:00,520 --> 00:45:03,920
Speaker 1: that then only you know ten percent of them will hit.

964
00:45:03,800 --> 00:45:06,040
Speaker 2: It, exactly like if you know a Gaussian distribution, you

965
00:45:06,040 --> 00:45:08,680
Speaker 2: can characterize the width of it. It doesn't capture the

966
00:45:08,680 --> 00:45:11,160
Speaker 2: whole distribution. It's just like a characteristic number that tells

967
00:45:11,160 --> 00:45:14,319
Speaker 2: you roughly how wide it is. And there's a possibility

968
00:45:14,320 --> 00:45:16,279
Speaker 2: you go past that with and you still interact with

969
00:45:16,280 --> 00:45:18,480
Speaker 2: the proton. And there's a possibility you go below that

970
00:45:18,520 --> 00:45:20,600
Speaker 2: width and you don't interact with the proton. So it's

971
00:45:20,640 --> 00:45:24,120
Speaker 2: a quantum fuzzy definition of size. That's fuzzy in another

972
00:45:24,160 --> 00:45:26,720
Speaker 2: way too, because it depends on the thing you're touching

973
00:45:26,719 --> 00:45:30,520
Speaker 2: it with, Like protons will react to electrons differently than

974
00:45:30,520 --> 00:45:33,840
Speaker 2: they will react to muons or react to neutrinos. So

975
00:45:33,880 --> 00:45:37,000
Speaker 2: the whole concept of size is really about the interaction

976
00:45:37,280 --> 00:45:41,080
Speaker 2: of two things. It's not inherent property of the object anyway,

977
00:45:41,480 --> 00:45:44,160
Speaker 2: at least this quantum definition of size.

978
00:45:43,880 --> 00:45:45,719
Speaker 1: I see, like it depends on the experiment. The width

979
00:45:45,760 --> 00:45:47,600
Speaker 1: of a proton. You can't talk about the width of

980
00:45:47,640 --> 00:45:49,600
Speaker 1: a proton. You have to say what's the width of

981
00:45:49,640 --> 00:45:52,200
Speaker 1: a proton when it's interacting with electrons? Or what's the

982
00:45:52,200 --> 00:45:55,480
Speaker 1: width of a proton when it's interacting with hot dog ginos?

983
00:45:56,040 --> 00:45:57,320
Speaker 1: Even then it's fuzzy and you kind of have to

984
00:45:57,320 --> 00:45:59,719
Speaker 1: make a call and say, well, you know it's about

985
00:45:59,800 --> 00:46:01,399
Speaker 1: here that it starts to taper off.

986
00:46:02,000 --> 00:46:03,120
Speaker 2: Yeah, exactly, all.

987
00:46:03,080 --> 00:46:05,680
Speaker 1: Right, So then let not switch to photons. Do the

988
00:46:05,719 --> 00:46:07,759
Speaker 1: same thing apply to photons? Like does it depend on

989
00:46:07,760 --> 00:46:08,480
Speaker 1: how we measure it?

990
00:46:08,520 --> 00:46:10,880
Speaker 2: So this is tricky because photons don't like to interact

991
00:46:10,920 --> 00:46:13,520
Speaker 2: with each other. You can't just like shoot one photon

992
00:46:13,560 --> 00:46:15,440
Speaker 2: at another and say, like how often are they going

993
00:46:15,520 --> 00:46:18,040
Speaker 2: to touch each other this kind of stuff. Remember, photons

994
00:46:18,120 --> 00:46:20,880
Speaker 2: only interact with things that have electric charge. So you

995
00:46:20,880 --> 00:46:24,280
Speaker 2: can shoot photons at electrons, but you can't shoot photons

996
00:46:24,320 --> 00:46:27,319
Speaker 2: at photons and see them interact. Very often. When they do,

997
00:46:27,360 --> 00:46:31,400
Speaker 2: it's because they've actually spontaneously transformed into electrons and positrons

998
00:46:31,440 --> 00:46:33,319
Speaker 2: and then interacted. So I was thinking about it, and

999
00:46:33,400 --> 00:46:35,080
Speaker 2: there's another way you might be able to get a

1000
00:46:35,160 --> 00:46:38,120
Speaker 2: sense for the length of a photon because photons don't

1001
00:46:38,120 --> 00:46:40,560
Speaker 2: interact with each other the same way particles do, but

1002
00:46:40,600 --> 00:46:43,640
Speaker 2: they can interfere with each other. If photons are at

1003
00:46:43,680 --> 00:46:46,719
Speaker 2: the same place at the same time, they will interfere,

1004
00:46:46,760 --> 00:46:49,359
Speaker 2: like the way we have interferometers. You know, we talk

1005
00:46:49,400 --> 00:46:52,080
Speaker 2: about interference, you get like light patches and dark patches.

1006
00:46:52,120 --> 00:46:54,279
Speaker 1: Wait, wait, let maybe take a step back. What is

1007
00:46:54,280 --> 00:46:56,120
Speaker 1: it that you're trying to do. You're trying to measure

1008
00:46:56,600 --> 00:46:59,080
Speaker 1: the size of this wave packet or the size of

1009
00:46:59,120 --> 00:47:01,640
Speaker 1: the fuzziness an electron. Is that kind of what you're

1010
00:47:01,640 --> 00:47:02,000
Speaker 1: trying to do.

1011
00:47:02,080 --> 00:47:04,080
Speaker 2: I'm thinking about how to measure the length of that

1012
00:47:04,120 --> 00:47:06,520
Speaker 2: wave packet of a photon, And I was thinking about

1013
00:47:06,560 --> 00:47:10,080
Speaker 2: if you send two photons through an interference experiment, Like,

1014
00:47:10,280 --> 00:47:12,439
Speaker 2: do the interfere with each other? They will if they're

1015
00:47:12,480 --> 00:47:14,640
Speaker 2: right on top of each other. They won't if they're

1016
00:47:14,680 --> 00:47:18,040
Speaker 2: really separated, Like if you wait ten seconds between shooting photons,

1017
00:47:18,120 --> 00:47:20,520
Speaker 2: they won't interfere with each other. There's some point in

1018
00:47:20,560 --> 00:47:23,240
Speaker 2: which if you send two photons through the experiment close

1019
00:47:23,360 --> 00:47:26,719
Speaker 2: enough together in time that their wave packets are overlapping,

1020
00:47:26,920 --> 00:47:29,120
Speaker 2: that they will interfere with each other. And so I'm

1021
00:47:29,120 --> 00:47:32,120
Speaker 2: thinking that's like one way to define the width of

1022
00:47:32,200 --> 00:47:35,320
Speaker 2: the wave packet of each photon is like how close

1023
00:47:35,400 --> 00:47:37,719
Speaker 2: they have to be to each other in time, which

1024
00:47:37,760 --> 00:47:40,680
Speaker 2: then gets translated to distance so that they start interfering

1025
00:47:40,680 --> 00:47:41,200
Speaker 2: with each other.

1026
00:47:41,400 --> 00:47:44,160
Speaker 1: Doesn't light interact with electrons? For example, So like we

1027
00:47:44,280 --> 00:47:47,000
Speaker 1: use electrons like you you said, to measure the width

1028
00:47:47,000 --> 00:47:49,040
Speaker 1: of a proton, couldn't we kind of flip it and

1029
00:47:49,160 --> 00:47:52,120
Speaker 1: use an electron to measure the width of a light particle?

1030
00:47:52,320 --> 00:47:54,200
Speaker 1: Like what if I sit an electron there on a

1031
00:47:54,239 --> 00:47:57,480
Speaker 1: table and I just shoot photons at it? Wouldn't this

1032
00:47:57,600 --> 00:47:59,920
Speaker 1: sort of tell me how whine my photon?

1033
00:48:00,480 --> 00:48:01,880
Speaker 2: Yeah? But are we talking about the length of a

1034
00:48:01,920 --> 00:48:03,640
Speaker 2: photon or the width of a photon?

1035
00:48:03,760 --> 00:48:06,040
Speaker 1: Wait? Wait? Meaning like is it light shape like a

1036
00:48:06,040 --> 00:48:09,200
Speaker 1: hot dog. Let's assume the light is shape like a

1037
00:48:09,200 --> 00:48:11,879
Speaker 1: meat ball. Wouldn't the length also tell you the width.

1038
00:48:12,120 --> 00:48:14,600
Speaker 2: The length or the width it depends on the uncertainty

1039
00:48:14,640 --> 00:48:16,840
Speaker 2: of its production. Right, The entire length of the photon

1040
00:48:16,920 --> 00:48:19,720
Speaker 2: comes from the uncertainty you have in how it was produced.

1041
00:48:19,760 --> 00:48:23,000
Speaker 2: It's either infinitely long if it's perfectly well measured, or

1042
00:48:23,080 --> 00:48:25,600
Speaker 2: it's very very tiny if it's very uncertain in its energy.

1043
00:48:26,040 --> 00:48:28,960
Speaker 2: So the width might come from a different uncertainty. So, yeah,

1044
00:48:29,040 --> 00:48:30,640
Speaker 2: if you want to talk about the width of the photon,

1045
00:48:30,760 --> 00:48:33,120
Speaker 2: like which direction does it come out of the laser,

1046
00:48:33,200 --> 00:48:36,680
Speaker 2: this uncertainty there in the photon's width as well as

1047
00:48:36,719 --> 00:48:38,760
Speaker 2: in its length. That could be a different number.

1048
00:48:38,840 --> 00:48:40,640
Speaker 1: But I feel like when you were talking about the proton,

1049
00:48:40,920 --> 00:48:43,400
Speaker 1: you were using the word length to mean it's.

1050
00:48:43,280 --> 00:48:46,680
Speaker 2: With Yeah, for proton, we really are measuring its width

1051
00:48:46,880 --> 00:48:48,160
Speaker 2: in that case. You're right, So.

1052
00:48:48,120 --> 00:48:53,799
Speaker 1: You're assuming protons are meat bull shaped. Well, I mean

1053
00:48:53,840 --> 00:48:56,120
Speaker 1: that is important, right, No, you're right. Yeah, you're right,

1054
00:48:56,680 --> 00:48:59,040
Speaker 1: you're assuming protons are meat bull shapes, But you're not

1055
00:48:59,120 --> 00:49:01,640
Speaker 1: assuming that light is meatball shape. You're assuming it might

1056
00:49:01,640 --> 00:49:03,239
Speaker 1: be hot dog shape or not. I don't know.

1057
00:49:03,400 --> 00:49:05,880
Speaker 2: Yeah, absolutely, I'm using the meatbon model of a proton,

1058
00:49:05,960 --> 00:49:08,879
Speaker 2: the hot dog model of a photon, and somebody else

1059
00:49:08,960 --> 00:49:12,040
Speaker 2: might have a different you know, maybe a French version

1060
00:49:12,040 --> 00:49:13,760
Speaker 2: of it, right whe there's a pastry version.

1061
00:49:13,760 --> 00:49:17,360
Speaker 1: Donut, a French fry version, the pompfleet model.

1062
00:49:17,719 --> 00:49:17,879
Speaker 3: Yes.

1063
00:49:18,000 --> 00:49:20,839
Speaker 2: So to measure the width of a photon, you could

1064
00:49:20,840 --> 00:49:22,919
Speaker 2: scan a beam across a bunch of electrons and see

1065
00:49:22,920 --> 00:49:24,359
Speaker 2: when they interact and then will give you a sense

1066
00:49:24,400 --> 00:49:26,120
Speaker 2: for like the width of your beam. And if you

1067
00:49:26,120 --> 00:49:28,279
Speaker 2: slow it down to individual photons, if you go a

1068
00:49:28,320 --> 00:49:30,480
Speaker 2: sense of the width of the wave packet of the photon.

1069
00:49:30,680 --> 00:49:32,480
Speaker 2: I think to get a sense of the length of

1070
00:49:32,520 --> 00:49:34,640
Speaker 2: a photon, you might want to see how the photons

1071
00:49:34,880 --> 00:49:38,000
Speaker 2: overlap in an interference experiment, see when they start interfering.

1072
00:49:38,160 --> 00:49:41,200
Speaker 2: That proves something we call coherence length of the photon.

1073
00:49:41,719 --> 00:49:43,279
Speaker 1: I wonder if you can measure the length of a

1074
00:49:43,320 --> 00:49:47,520
Speaker 1: hot dog photon by measuring by using time, Like, if

1075
00:49:47,640 --> 00:49:50,719
Speaker 1: there's more uncertainty in when you receive the photon, would

1076
00:49:50,719 --> 00:49:52,840
Speaker 1: that tell you that it's a really long it's a

1077
00:49:52,840 --> 00:49:56,480
Speaker 1: foot long hot dog. Where I suppose if the uncertainty

1078
00:49:56,520 --> 00:49:59,359
Speaker 1: and when you receive the photon is very short. It's like, oh,

1079
00:49:59,360 --> 00:49:59,880
Speaker 1: it's a vienna.

1080
00:50:00,320 --> 00:50:02,239
Speaker 2: Yeah, And principle, if you know the energy and uncertainty,

1081
00:50:02,440 --> 00:50:04,400
Speaker 2: you can just define the length. I was trying to

1082
00:50:04,400 --> 00:50:07,040
Speaker 2: think about a way to like experimentally measure another sense

1083
00:50:07,080 --> 00:50:09,240
Speaker 2: of the length in terms of like when two photons

1084
00:50:09,239 --> 00:50:11,800
Speaker 2: overlap with each other, rather than just thinking about that

1085
00:50:11,960 --> 00:50:15,200
Speaker 2: length of an individual photon theoretically. But yeah, you can

1086
00:50:15,200 --> 00:50:18,440
Speaker 2: definitely define the length of an individual photon theoretically from

1087
00:50:18,480 --> 00:50:20,960
Speaker 2: its energy and the uncertainty, which again is coupled to

1088
00:50:21,000 --> 00:50:22,680
Speaker 2: the uncertainty and its time measurement.

1089
00:50:22,920 --> 00:50:25,120
Speaker 1: So I feel like maybe the headline from this podcast

1090
00:50:25,120 --> 00:50:29,120
Speaker 1: episode is a physicists claim light is shaped like a

1091
00:50:29,160 --> 00:50:29,520
Speaker 1: hot dog.

1092
00:50:32,600 --> 00:50:34,160
Speaker 2: You know, one thing I love about this podcast is

1093
00:50:34,200 --> 00:50:36,279
Speaker 2: I've never have any idea where it's going to end

1094
00:50:36,320 --> 00:50:38,480
Speaker 2: up going. There's no way to prepare for this.

1095
00:50:38,960 --> 00:50:40,600
Speaker 1: There's an uncertainty about its length.

1096
00:50:40,640 --> 00:50:44,640
Speaker 2: Also, the topic, the concept, the analogies we end up using.

1097
00:50:44,760 --> 00:50:47,760
Speaker 2: This is proof that this podcast is unscripted because nobody

1098
00:50:47,760 --> 00:50:48,640
Speaker 2: could write this stuff.

1099
00:50:51,440 --> 00:50:54,320
Speaker 1: Well we are, we're writing it right now, Daniel. It's happening.

1100
00:50:54,320 --> 00:50:55,480
Speaker 1: It's happening, we're living it.

1101
00:50:55,520 --> 00:50:55,719
Speaker 3: Man.

1102
00:50:57,280 --> 00:50:59,279
Speaker 1: Well, I mean, would you I feel that that's the

1103
00:50:59,280 --> 00:51:01,200
Speaker 1: biggest thing that I'm getting out of this is that

1104
00:51:01,360 --> 00:51:03,960
Speaker 1: you know, you're in your thought point of view. A

1105
00:51:04,000 --> 00:51:07,839
Speaker 1: photon is not spherical, it's maybe has different dimensions to it.

1106
00:51:07,960 --> 00:51:09,880
Speaker 2: Yeah, I hadn't thought about the width of a photon,

1107
00:51:09,960 --> 00:51:13,080
Speaker 2: but you're right. It has all the same theoretical questions

1108
00:51:13,120 --> 00:51:16,200
Speaker 2: to it and experimental trickery to measure the width of it.

1109
00:51:16,280 --> 00:51:18,000
Speaker 2: But the width and the length of a photon could

1110
00:51:18,040 --> 00:51:20,200
Speaker 2: be very different. You could have a source of photons

1111
00:51:20,200 --> 00:51:23,200
Speaker 2: that's very uncertain in length and very certain in width.

1112
00:51:23,360 --> 00:51:26,000
Speaker 1: I think that you know, as you you gave a

1113
00:51:26,040 --> 00:51:29,239
Speaker 1: proton of definite size, right like in physics you have

1114
00:51:29,320 --> 00:51:31,480
Speaker 1: a size with plus or mind is a certain amount

1115
00:51:31,520 --> 00:51:33,919
Speaker 1: of uncertainty. If you had to do that for a light,

1116
00:51:34,080 --> 00:51:36,560
Speaker 1: for a photon, like maybe an everyday photon that we

1117
00:51:36,600 --> 00:51:39,240
Speaker 1: see every day, what would you say it is its length?

1118
00:51:39,680 --> 00:51:42,200
Speaker 2: Yeah, that's a great question. You know, a typical photon

1119
00:51:42,280 --> 00:51:45,560
Speaker 2: that's like coming out of the light that's made from

1120
00:51:45,600 --> 00:51:47,560
Speaker 2: a light bulb in your house, that's a glow of

1121
00:51:47,600 --> 00:51:49,839
Speaker 2: like a little piece of metal. So there's a very

1122
00:51:49,880 --> 00:51:52,759
Speaker 2: wide spread in the uncertainty of those photons.

1123
00:51:52,840 --> 00:51:56,040
Speaker 1: Oh cool, Now, how would say it compares to its

1124
00:51:56,080 --> 00:52:00,200
Speaker 1: width like our photons hot like the every day times

1125
00:52:00,239 --> 00:52:02,520
Speaker 1: we see hot dyck shaped or are they football shaped

1126
00:52:02,600 --> 00:52:05,960
Speaker 1: or are they more spherically? Tis like, what kind of fun?

1127
00:52:06,080 --> 00:52:07,719
Speaker 1: What kind of bunch should I get to eat it?

1128
00:52:09,719 --> 00:52:11,960
Speaker 2: I think it's probably curved, so you should get a croissant?

1129
00:52:12,520 --> 00:52:15,480
Speaker 2: Oh no, I don't know the answer that it depends

1130
00:52:15,480 --> 00:52:18,399
Speaker 2: a lot on the source for a typical filament from

1131
00:52:18,440 --> 00:52:20,719
Speaker 2: like an incandescent bulb. There's again going to be a

1132
00:52:20,760 --> 00:52:23,319
Speaker 2: lot of uncertainty in the direction, So these things are

1133
00:52:23,320 --> 00:52:26,359
Speaker 2: going to be pretty fat. Maybe there's sausage paddies after all.

1134
00:52:26,640 --> 00:52:28,759
Speaker 1: Oh yeah, oh man, I hadn't even thought about that

1135
00:52:28,800 --> 00:52:31,160
Speaker 1: snag Like they could be like pancakes flying at you

1136
00:52:31,920 --> 00:52:32,760
Speaker 1: face face.

1137
00:52:32,520 --> 00:52:34,440
Speaker 2: Forward, Yeah, more sideways.

1138
00:52:34,600 --> 00:52:37,200
Speaker 1: Yeah. Interesting. All right, So I guess we sort of

1139
00:52:37,280 --> 00:52:39,239
Speaker 1: answered the question how long a photon is?

1140
00:52:39,520 --> 00:52:41,680
Speaker 2: We know that these things are really hard to think about,

1141
00:52:41,760 --> 00:52:43,400
Speaker 2: and that the answer depends a little bit on the

1142
00:52:43,480 --> 00:52:46,040
Speaker 2: question you're asking and exactly how you want to answered,

1143
00:52:46,200 --> 00:52:49,239
Speaker 2: And along the way you often have to redefine what

1144
00:52:49,320 --> 00:52:51,319
Speaker 2: you mean by your question in order to get a

1145
00:52:51,360 --> 00:52:53,160
Speaker 2: specific unsatisfying answer.

1146
00:52:53,600 --> 00:52:55,120
Speaker 1: Yeah, and in the enda, I guess it's all a

1147
00:52:55,160 --> 00:52:58,720
Speaker 1: little bit fuzzy due to the fuzzy nature of the universe.

1148
00:52:59,000 --> 00:53:01,239
Speaker 2: But put enough mustard it it'll be delicious.

1149
00:53:01,560 --> 00:53:07,600
Speaker 1: Yeah, it's a little fuzzy though. The Fuzzy hot Dog Podcast.

1150
00:53:08,320 --> 00:53:12,280
Speaker 1: All right, well, another interesting dive into the quantum nature

1151
00:53:12,320 --> 00:53:15,200
Speaker 1: of the universe and how even simple questions like how

1152
00:53:15,200 --> 00:53:18,080
Speaker 1: big is a photon or what shape it has requires

1153
00:53:18,280 --> 00:53:22,920
Speaker 1: a whole conversation about the nature of length and what

1154
00:53:23,080 --> 00:53:24,840
Speaker 1: even means to be something in the universe.

1155
00:53:25,000 --> 00:53:28,120
Speaker 2: That's right, the most basic questions are the hardest to answer.

1156
00:53:28,480 --> 00:53:30,440
Speaker 1: All right, well, we hope you enjoyed that. Thanks for

1157
00:53:30,520 --> 00:53:32,000
Speaker 1: joining us. See you next time.

1158
00:53:36,719 --> 00:53:39,600
Speaker 2: For more science and curiosity, come find us on social

1159
00:53:39,640 --> 00:53:43,560
Speaker 2: media where we answer questions and post videos. We're on Twitter,

1160
00:53:43,680 --> 00:53:47,319
Speaker 2: disc Org, Instant, and now TikTok. Thanks for listening, and

1161
00:53:47,360 --> 00:53:50,080
Speaker 2: remember that Daniel and Jorge Explain the Universe is a

1162
00:53:50,120 --> 00:53:54,560
Speaker 2: production of iHeartRadio. For more podcasts from iHeart Radio, visit

1163
00:53:54,640 --> 00:53:58,680
Speaker 2: the iHeartRadio app, Apple Podcasts, or wherever you listen to

1164
00:53:58,760 --> 00:54:03,360
Speaker 2: your favorite shows.