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Speaker 4: Terms apply. Hey Daniel, when you think about a photon,

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Speaker 4: what image comes to mind?

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Speaker 1: Ooh?

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Speaker 4: Depends on what what you've been smoking that day?

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Speaker 1: Yes, and also on the context. Are we talking about

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Speaker 1: light from distant stars or rainbows or single photon lasers

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Speaker 1: or what?

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Speaker 4: What aren't they all the same. Like a photon is

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Speaker 4: a photon, isn't it.

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Speaker 1: Nobody really knows what a photon is. There's something weird

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Speaker 1: and mysterious we might never fully understand.

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Speaker 4: So you're just gonna leave us in the dark. You're

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Speaker 4: not gonna shed any light on it.

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Speaker 1: That's as bright as I can be on the topic.

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Speaker 4: Hi am horehad Mad cartoonists and the author of Oliver's

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Speaker 4: Great Big Universe.

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Speaker 1: Hi. I'm Daniel. I'm a particle physicist and professor at

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Speaker 1: UC Irvine, and I'm still hunting for a brilliant explanation

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Speaker 1: about photons.

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Speaker 4: I thought brilliance was your job description. Isn't it your

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Speaker 4: job to provide that brilliance.

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Speaker 1: My job is to hunt for the brilliance, to try

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Speaker 1: to mine the truth from the firmament of reality. We

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Speaker 1: don't always find it.

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Speaker 4: I guess it's hard to shine light on some of

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Speaker 4: 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.

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Speaker 4: Enough, somebody has a light bulb moment there. But what

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Speaker 4: do you mean? Are you saying photons depend on where

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Speaker 4: they come from?

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Speaker 1: I'm saying that the language of physics we use to

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Speaker 1: explain things uses as the basic mental building blocks. Things

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Speaker 1: we do understand waves and bits of sand and tiny

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Speaker 1: little particulate stuff, and none of those things really completely

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Speaker 1: and fully describe the photon. It's those things, but also

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Speaker 1: something else.

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Speaker 4: I see. It's a language issue. Blame it on the

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Speaker 4: linguists if we don't understand the universe. It's not the

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Speaker 4: physicists fault.

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Speaker 1: It also turns out to be fundamental to how we

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Speaker 1: do science. We often tell different stories about the same

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Speaker 1: kind of stuff depending on the question we are asking.

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Speaker 1: None of our science is totally exact and complete. It's

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Speaker 1: always approximate. And which approximation, which idea we use, which

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Speaker 1: conceptualization is relevant, depends on the questions we're asking.

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Speaker 4: Sounds like it's a big relativity problem because it's all relative.

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Speaker 1: It's relatively complicated.

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Speaker 4: Yeah, indeed, But anyways, welcome to our podcast, Daniel and

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Speaker 4: Jorge Explain the Universe, a production of iHeartRadio, in.

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Speaker 1: Which we take the whole universe as the context for

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Speaker 1: our goal to understand things. We want to understand, how

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Speaker 1: droplets form into hurricanes, how tiny little quarks make protons,

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Speaker 1: how enormous masses of stuff swirl into black holes. We

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Speaker 1: want to answers for everything, and we hope one day

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Speaker 1: to be able to stitch those answers together into a single, comprehensive,

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Speaker 1: complete understanding of the universe, even though that might actually

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Speaker 1: be impop.

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Speaker 4: Yeah, we try to track the journey of humanity from

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Speaker 4: the shadows into the shining light of understanding and comprehension

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Speaker 4: about this amazing universe we live in. Yeah, even if

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Speaker 4: it sometimes takes a few stories or different stories along

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Speaker 4: the way.

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Speaker 1: The history of physics is seeing stuff we don't understand

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Speaker 1: and then cobbling together some sort of mathematical explanation for

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Speaker 1: what might be going on. And the bigger picture is

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Speaker 1: to then try to weave those explanations together into a

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Speaker 1: single coherent idea. But that task is still not finished,

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Speaker 1: and it leaves us sometimes in an awkward situation of

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Speaker 1: not being able to answer pretty basic questions about what's

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Speaker 1: going on out there.

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Speaker 4: Are you saying physicists can't get their story straight. It's

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Speaker 4: a little suspicious.

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Speaker 1: I'm saying the universe is a little bit lack Russiamon.

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Speaker 1: You know, the story you tell depends on your context.

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Speaker 1: But this is not something that only physicists. Do you know,

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Speaker 1: if I ask you how the baseball game went yesterday,

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Speaker 1: you tell me a story about the teams and who

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Speaker 1: was playing well and who was struggling. You put it

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Speaker 1: in context to make it excit. You don't just give

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Speaker 1: me a dry list of what happened to every single

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Speaker 1: particle in the vicinity of the stadium that day.

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Speaker 4: But there'd just be one story about who won and

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Speaker 4: who lost.

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Speaker 1: If you think that's the story, right, Maybe the story

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Speaker 1: is something else, the changing of the hot dogs, how

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Speaker 1: the mustard now tastes, you know, the weather. Everybody might

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Speaker 1: ask different questions about the same sets of events, and

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Speaker 1: then they might need to use different physical concepts, even

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Speaker 1: different mathematical formalisms to get those answers, which makes a

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Speaker 1: very complicated answer very basic sounding questions.

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Speaker 4: Right, right, Sometimes you need hot dog particles, sometimes you

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Speaker 4: need baseball particles.

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Speaker 1: Yeah, exactly. You can build a whole universe on the

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Speaker 1: hot dog theory. Hot dogs are the fundamental component, and

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Speaker 1: what's inside them doesn't really matter, right.

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Speaker 4: Right, Is it the hot dog on or the hot logino.

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Speaker 1: The whole brilliance of hot dogs is just enjoying them

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Speaker 1: and not even caring what they're made at it.

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Speaker 4: What's the shape of a hot dog on and how

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Speaker 4: long is it?

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Speaker 1: That depends on which city you're in, you know.

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Speaker 4: Yeah, yeah, or which country too, that's.

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Speaker 1: Right, and your relative velocity, because some of these things

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Speaker 1: can be length contracted.

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Speaker 4: That's right. If you eat it fast, then it's a

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Speaker 4: lot shorter than it is.

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Speaker 1: If you're at high velocity relative to your hot dog,

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Speaker 1: it will seem shorter. So, yeah, somebody shoots a hot

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Speaker 1: dog into your mouth you're the speed of light, then

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Speaker 1: you're gonna have an interesting experience.

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Speaker 4: But then it depends on which direction it is subbody, Right,

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Speaker 4: if it's shut it on the side, it's still going

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Speaker 4: to be the same length.

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Speaker 1: Yeah, exactly, it's just going to be thinner.

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Speaker 4: Yeah, let's just spend the rest of the episode talking

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Speaker 4: about hot dog physics.

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Speaker 1: High velocity hot dog physics, relativistic hot dog physics, a

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Speaker 1: topic nobody has ever explored. We can be the first

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Speaker 1: to write a paper in the Journal of hot dog Physics.

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Speaker 4: Well, I think we're definitely the first to ever talk

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Speaker 4: about it in a physics podcast. I'm thinking, I don't know,

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Speaker 4: I haven't done the exhaustive literature search.

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Speaker 1: Somebody out there let us know if we need to

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Speaker 1: cite you.

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Speaker 4: Yeah, somebody else do the research for us. But anyways,

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Speaker 4: it is interesting to talk about how long things are,

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Speaker 4: you know, basic questions like that about everyday objects we

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Speaker 4: see every day.

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Speaker 1: It is often really fruitful, but sometimes frustrating to ask intuitive,

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Speaker 1: natural questions about the kind of things we think the

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Speaker 1: universe is made out of. We think everything out there

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Speaker 1: has certain properties, it has a size, a link, the mass,

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Speaker 1: et cetera. And so we try to apply those concepts,

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Speaker 1: these things we're familiar with from the kind of stuff

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Speaker 1: we're used to interacting with, and apply that to quantum objects.

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Speaker 1: But it doesn't always quite work.

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Speaker 4: Yes, we've found out the quantum world is very straying,

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Speaker 4: very mysterious, very uncertain, and very hard for our simple

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Speaker 4: brain sometimes to understand and capture and to get an

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Speaker 4: intuitive understanding of it.

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Speaker 1: But that doesn't mean it's impossible, and that doesn't mean

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Speaker 1: it's not useful. In fact, it's very helpful for shining

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Speaker 1: a light onto what we do understand and what we

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Speaker 1: don't understand, and it can help you make a better

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Speaker 1: mental picture for what's going on at the quantum level.

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Speaker 4: Right, But the question is can we shine a light

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Speaker 4: on light itself? And so to the on the podcast,

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Speaker 4: we'll be tackling the question how long is a photon?

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Speaker 4: Now it is? Is that a photon coming off of

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Speaker 4: a hot dog? Or does it matter where it's bouncing

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Speaker 4: off of.

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Speaker 1: A hot dog? Colored photon? Wow? What is the color

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Speaker 1: of a hot dog?

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Speaker 4: What is the color of a hot dog? Sounds like

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Speaker 4: the topic of a philosophy class here.

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Speaker 1: If you eat your hot dog with eyes closed, does

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Speaker 1: it have a color or not? I wonder if there's

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Speaker 1: a paint shade out there that's called hot dog.

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Speaker 4: I think people usually avoid having the runs painted hot dog.

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Speaker 1: There's probably more adjectives to it, like bright, summer hot dog.

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Speaker 4: Or something summer baseball hot dog, home run, the hot dog,

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Speaker 4: hot dog, vapor.

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Speaker 1: Wild mountain hot dog.

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Speaker 4: There's so many shades to a hot dog, isn't there?

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Speaker 1: But we're not here to talk about hot dogs, though

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Speaker 1: it seems like we're gonna. We're here to try our

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Speaker 1: best to answer a very simple but very hard question

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Speaker 1: about the nature of light.

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Speaker 5: Mmm.

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Speaker 4: Now, how long it's a photon? Is that a question

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Speaker 4: about its length? Or like how long it lasts?

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Speaker 1: Oh? I interpreted it as a question about its length,

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Speaker 1: like its physical extent. Photons can last forever, you know,

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Speaker 1: their lifetime is potentially infinite. You shoot a photon into

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Speaker 1: empty space, it'll just keep going forever.

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Speaker 4: But you can kill a photon, canjin You can.

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Speaker 1: Kill a photon? Yes, absolutely, you can absorb it, you

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Speaker 1: can interact with it. But a photon on its own

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Speaker 1: will not like necessarily decay.

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Speaker 4: Can it ever? Like isn't Is there a possibility for

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Speaker 4: it to, you know, have its energy convert into something else?

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Speaker 1: Absolutely, a photon flying through space can just fly through space,

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Speaker 1: but it can also turn into an electron and positron

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Speaker 1: and then back into a photon, or into a muon

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Speaker 1: or an anti muon, and then back into a photon or

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Speaker 1: all sorts of other stuff. So there's lots of quantum

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Speaker 1: possibilities constantly for photons.

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Speaker 4: Can it turn into a hot dog technically, like you know,

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Speaker 4: in the infinity of infinities? Is there a slight chance

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Speaker 4: it can turn it suddenly into hot Yes.

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Speaker 1: There's a slight chance a very high energy photon could

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Speaker 1: turn into a mutually charged hot dog momentarily.

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Speaker 4: Hopefully it doesn't turn into hot dog inside your eye and.

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Speaker 1: That tells me exactly what I want to paint my

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Speaker 1: room next year, which is quantum hot dog.

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Speaker 4: Oh boy, it's like it's different shades at the same.

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Speaker 1: Time, exactly Shrewdinger's hot.

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Speaker 4: It's like yellow mustard red ketchup. But it depends on

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Speaker 4: how you look at it, kind of like the dress. Anyways,

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Speaker 4: that's a very spicy idea. All right, let's talk about

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Speaker 4: this question. But first we were wondering how many people

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Speaker 4: out there had thought about the length of a photon,

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Speaker 4: or even if photons have length.

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Speaker 1: Thanks very much to everybody who answered this question. I

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Speaker 1: only got one response online. So I walked around campus

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Speaker 1: at U see Ermine last week and I asked a

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Speaker 1: bunch of psych majors and other random people about photons.

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Speaker 4: All right, well, if you spot a physicist with a

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Speaker 4: microphone on the Ucroine campus, make sure to I don't know,

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Speaker 4: runaway or approach if you think you can answer physics

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Speaker 4: questions on.

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Speaker 1: The spot, or even if you don't love to hear

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Speaker 1: your thoughts.

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Speaker 4: All right, so think about it for a second. How

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Speaker 4: long do you think a photon is? Here's what people

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Speaker 4: had to say.

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Speaker 5: I don't think we don't know about that yet because

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Speaker 5: of the mathematics going weird, since the photon is traveling

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Speaker 5: in speed of the light.

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Speaker 1: So that's my guess.

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Speaker 6: Oh my gosh, I don't know.

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Speaker 4: I'm gonna say and like, uh like ten to the

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Speaker 4: power of negative twenty centimeters.

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Speaker 7: Let's say, so I guess photons.

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Speaker 4: They don't have a mask or that agment, right, So

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Speaker 4: it depends on the wavelength light.

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Speaker 7: No, I wouldn't even have like a guess of like length.

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Speaker 1: Yeah, a long in science, Yeah, I don't know.

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Speaker 8: I remember if from bokam.

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Speaker 4: Okay, like maybe inches Okay.

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Speaker 7: Yeah, I wouldn't even know I would photons. When I

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Speaker 7: think of physics, I think it's like small like particles, yes,

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Speaker 7: and then I'm thinking like centimeters and like in minute

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Speaker 7: signs two millimeters.

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

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Speaker 6: I major in a criminal justice, so completely outside of

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Speaker 6: my major.

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Speaker 1: There's a photon, a particle light? Yes, how long is it?

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Speaker 4: I'm gonna say point zero zero one light years. I

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Speaker 4: don't know, like some random like maybe like zero point

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Speaker 4: one microns. I don't know, all right, some pretty good answers,

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Speaker 4: some of them are very specific. Zero point one microns

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Speaker 4: ten to the power of negative twenty centimeters.

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Speaker 1: There's a huge, huge range of answers here. I think

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Speaker 1: the biggest one is probably zero point zero zero one

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Speaker 1: light years. That turns out to be a very big number.

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Speaker 4: Well, I'm impressed that they even stuck to the metric system.

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Speaker 4: I mean, everyone nobody switched to inches or miles.

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Speaker 1: You think photons are metric? I don't know. Yeah, I

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Speaker 1: believe in imperial photons.

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Speaker 4: I believe photons are king, but you know, I think

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Speaker 4: they should stick to the more reasonable metric system.

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Speaker 1: That's why Darth Vader is all black, because there are

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Speaker 1: no Imperial photons.

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Speaker 4: Wow, there took me three seconds there wait oh imperial. Yes, yes,

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Speaker 4: that was a very dark joke.

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

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Speaker 1: I totally set you up for that.

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Speaker 4: What would be the lightsaber joke?

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Speaker 1: Lightsabers only cut things in metric units. I don't know.

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Speaker 4: Lightsabers are about a meter long. There you go, all right, Well,

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Speaker 4: interesting azers. So Daniels dig into it. For first of all,

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Speaker 4: what is a photon? How do we define a photon? So,

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Speaker 4: a photon is like the minimum packet of light. If

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Speaker 4: you take a really bright source of light. You might

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Speaker 4: imagine it's just shooting out huge amounts of light. As

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Speaker 4: you dial it down, it'll get dimmer and dimmer and dimmer,

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Speaker 4: but it can't get infinitely dim. As you dial that

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Speaker 4: light source down, eventually you'll notice that the light is

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Speaker 4: actually discreete that it comes out in little packets rather

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Speaker 4: than just being dimmer and dimmer waves. So photons are

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Speaker 4: like the minimum unit of light. Wait, are you saying

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Speaker 4: that photons don't have a minimum energy.

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Speaker 1: Photons do not have a minimum energy. That's true, but

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Speaker 1: photons of a specific frequency have a fixed energy. And

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Speaker 1: if you have, for example, a laser at his very

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Speaker 1: specific wavelength, and you dial it down so it's dimmer

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Speaker 1: and dimmer and dimmer, eventually you're going to notice that

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Speaker 1: beam gets broken up and it comes out in pieces.

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Speaker 4: Like you lower the power to the laser, and eventually

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Speaker 4: you'll see it go down steps.

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Speaker 1: Yeah, exactly. It's just like everything else in our quantum world.

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Speaker 1: Matter is not continuous. You can't zoom in forever on

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Speaker 1: matter and have it always look the same way. As

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Speaker 1: you zoom in on matter, you notice that it has

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Speaker 1: a particular scale that at some point it breaks up

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Speaker 1: into discrete bits out of which everything is built, just

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Speaker 1: like the resolution on your screen. So light itself has

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Speaker 1: a resolution. It's made out of these little quantum bits,

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Speaker 1: these discrete building blocks. It's not perfectly smooth. And what

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Speaker 1: is that smallest bit for light? It's a photon. That's

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Speaker 1: what we call the photon. It's the smallest bit of light.

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Speaker 4: Like if I if I'm shooting lighters are in frequency,

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Speaker 4: the little steps that I see as I dial down

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Speaker 4: the power to it, that's what you would call a photon.

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Speaker 1: Exactly. Those are photons. And so if you have a

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Speaker 1: bunch of light, you can always ask how many photons

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Speaker 1: are there. There's a specific number. It has to be

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Speaker 1: an integer number of photons. You don't usually notice this

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Speaker 1: because the number of photons usually around hitting your eyeball

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Speaker 1: is enormous. It doesn't really matter that they're countable. But

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Speaker 1: as things get very very small, then you can notice

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Speaker 1: that you can have zero or one or two photons.

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Speaker 1: You can't have one point seven photons.

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Speaker 4: Now, how do we think about light? Is it like

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Speaker 4: you say, it's like a packet, Like it's a discrete

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Speaker 4: a little object.

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Speaker 1: Yeah, So this really gets at the heart of the question,

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Speaker 1: because how you describe this object helps you answer the

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Speaker 1: question how big is it? And the answer is that

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Speaker 1: we think about light in lots of different contradictory ways,

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Speaker 1: depending on the context. Sometimes we think about light as

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Speaker 1: like a tiny little object, but we think about it

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Speaker 1: like a particle which has no extent, just like zero

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Speaker 1: volume particle. Sometimes we ignore the quantum nature of it

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Speaker 1: because it doesn't matter. We're thinking about really bright sources

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Speaker 1: where the quantum nature is irrelevant, so we just think

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Speaker 1: about it as classical waves of electromagnetism, the way people

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Speaker 1: did two hundred years ago. And sometimes we think about

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Speaker 1: light interacting with quantum particles like light hitting an electron,

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Speaker 1: and then we think about it as a little quantum

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Speaker 1: packet and excitation in the electromagnetic field. So we have

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Speaker 1: lots of different pictures of what a photon is, and

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Speaker 1: the one that we use depends kind of on the

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Speaker 1: question we're.

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Speaker 4: Asking, well, so do you want to then tackle each

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Speaker 4: one of these different ways to look at it at

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Speaker 4: a time?

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Speaker 1: Yeah, sure, I think probably the most relevant in this

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Speaker 1: case is the quantum field theory one the last one

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Speaker 1: we talked about, But each one gives you a different answer.

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Speaker 4: All right, well, then let's maybe tackle each one of these.

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Speaker 4: What does quantum field theory say about the nature of light.

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Speaker 1: Quantum field theory is an updated version of classical field theory,

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Speaker 1: which sounds fancy, but it just says light is a

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Speaker 1: wave in the electromagnetic field. That's what Faraday and Maxwell

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Speaker 1: and those guys figured out a couple of hundred years ago.

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Speaker 1: That the universe is filled with this electromagnetic field, and

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Speaker 1: that waves in it are what we call light, and

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Speaker 1: so you can shoot light from one planet to another,

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Speaker 1: and the medium for that is the electromagnetic field. Even

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Speaker 1: though space is empty, it has these fields in it.

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Speaker 1: So light is a ripple in those fields. And we

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Speaker 1: talk about that all the time on the podcast. And

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Speaker 1: you have electric fields and magnetic fields and there are

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Speaker 1: ninety degrees from each other, and they're oscillating, and that's

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Speaker 1: what light is. From a classical point of view, that's

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Speaker 1: a traditional classical field theory. The quantum field theory version

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Speaker 1: of that is the same. It just says that there's

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Speaker 1: a minimum to how much you can oscillate, so that

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Speaker 1: as you turn it down you discover that you can't

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Speaker 1: turn it to any intensity there's certain steps. So the

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Speaker 1: quantum field theory version says the universe is filled with

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Speaker 1: this electromagnetic field which has certain steps in energy that

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Speaker 1: it can take.

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Speaker 4: Well, I guess, first of all, I wonder if listeners

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Speaker 4: sometimes they get confused by this like I do, which

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Speaker 4: is that you say light is a wave, but like

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Speaker 4: if I think that's rippling through a field, But if

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Speaker 4: I think of a wave like rippling through a lake

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Speaker 4: or my bathtub, it's something that ripples outwards in all directions,

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Speaker 4: Or if I think of it like a wave in

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Speaker 4: the ocean, it's like this broad thing that's moving and

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Speaker 4: undulating across kind of a wide area. But in terms

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Speaker 4: of light, it's not that right. It's not spreading in

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Speaker 4: all directions, and it's not broad like that.

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Speaker 1: It can be though, I mean, think about a star.

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Speaker 1: A star is emitting light, and it's emitting light in

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Speaker 1: all directions, and before you think about the quantum nature

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Speaker 1: of it, it is in fact spreading out. And that's

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Speaker 1: why stars seem more dim the further you are away

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Speaker 1: from them, right, because the intensity of the light drops

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Speaker 1: with the dis and squared, and so you have a

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Speaker 1: light waves which start out very intense and then they

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Speaker 1: spread out and so they get dimmer and dimmer. The

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Speaker 1: quantum version of that is the same, except that now

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Speaker 1: you have individual photons being sent out and close to

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Speaker 1: the star you have a high intensity of those photons,

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Speaker 1: and further away you have a smaller intensity of those photons.

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Speaker 1: And you can understand why the intensity of the photon

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Speaker 1: drops as you get further away because the space they're

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Speaker 1: feeling is getting bigger and bigger. And so if you

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Speaker 1: have like the same size eyeball and you're going to

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Speaker 1: have fewer number of photons hit your eyeball when you're

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Speaker 1: further away than when you are close up to the star.

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Speaker 4: Right, you can sort of think about it that way.

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Speaker 4: But I guess what do you call the photon? Then?

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Speaker 4: Is the photon the ripple that's shooting in all directions

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Speaker 4: or just if you catch that ripple in a particular spot,

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Speaker 4: you know what I mean? Like you can imagine a

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Speaker 4: star and it's rippling light out. Is a photon that

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Speaker 4: a ring that emanates from the star? Or what?

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Speaker 1: Yeah, great question? Say you slow the star down so

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Speaker 1: it's only emitting one photon at a time somehow, right,

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Speaker 1: like a single photon star Basically, we're just putting a

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Speaker 1: laser out there in space, but it's interesting to think

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Speaker 1: about how it could go in any direction. So then

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Speaker 1: any individual photon has the same probability to go in

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Speaker 1: any direction from the star if it's totally symmetric, and

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Speaker 1: so an individual photon has a ring of probability around

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Speaker 1: the star where it can go, and then when it

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Speaker 1: actually hits something, then the universe decides, Okay, this one's

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Speaker 1: over here, this one's over there. It's just like when

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Speaker 1: you shoot photons at a screen. They have a range

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Speaker 1: of possible locations where they can land, and then when

442
00:21:32,640 --> 00:21:35,399
Speaker 1: the photon actually hits that's when the universe decides this

443
00:21:35,520 --> 00:21:38,160
Speaker 1: photon's over here, and this photon's over there. So yeah,

444
00:21:38,200 --> 00:21:40,639
Speaker 1: individual photons come out in only one direction, but they

445
00:21:40,680 --> 00:21:43,480
Speaker 1: have a probability to come out in any direction. There's

446
00:21:43,480 --> 00:21:44,920
Speaker 1: a bit of a quantum wrinkle there.

447
00:21:45,119 --> 00:21:47,800
Speaker 4: So it's a little bit like the Schrodinger's cat. I

448
00:21:47,840 --> 00:21:49,920
Speaker 4: know you don't always like this analogy, but it's sort

449
00:21:49,920 --> 00:21:52,040
Speaker 4: of like the photon as it comes out of the

450
00:21:52,040 --> 00:21:55,280
Speaker 4: sun or the star, it's in all directions at the

451
00:21:55,280 --> 00:21:55,800
Speaker 4: same time.

452
00:21:56,200 --> 00:21:58,880
Speaker 1: It has the possibility, the probabilities to be in all

453
00:21:58,920 --> 00:22:01,479
Speaker 1: directions at the same time. You can only ever observe

454
00:22:01,520 --> 00:22:03,760
Speaker 1: it in one. So it depends what you mean by

455
00:22:03,840 --> 00:22:06,160
Speaker 1: like it is in those places at the same time.

456
00:22:06,320 --> 00:22:08,840
Speaker 1: It has the possibility to be there, can never be

457
00:22:08,920 --> 00:22:11,080
Speaker 1: seen to be in more than one place at once.

458
00:22:11,840 --> 00:22:16,440
Speaker 4: So like it emanates like a bubble basically out of

459
00:22:16,480 --> 00:22:20,119
Speaker 4: the star, that ripple that's the photon technically, right until

460
00:22:20,160 --> 00:22:22,560
Speaker 4: something hits it, or until it hits something in my

461
00:22:22,680 --> 00:22:24,439
Speaker 4: role to die and say okay, yeah, that's where I

462
00:22:24,520 --> 00:22:24,800
Speaker 4: was at.

463
00:22:25,080 --> 00:22:26,280
Speaker 1: Yeah, that's right.

464
00:22:26,560 --> 00:22:30,440
Speaker 4: So then these ripples, these bubble ripples, have a wavelength

465
00:22:30,480 --> 00:22:30,760
Speaker 4: to them.

466
00:22:30,920 --> 00:22:34,280
Speaker 1: Yeah, exactly, So these bubble ripples have a wavelength, right.

467
00:22:34,440 --> 00:22:37,440
Speaker 1: High energy photons have a very short wavelength, like blue

468
00:22:37,440 --> 00:22:41,760
Speaker 1: photons have a shorter wavelength a higher frequency than red photons,

469
00:22:41,760 --> 00:22:45,040
Speaker 1: which have a longer wavelength and a shorter frequency. And

470
00:22:45,080 --> 00:22:47,880
Speaker 1: so that immediately feels like ooh, that might be part

471
00:22:47,920 --> 00:22:50,679
Speaker 1: of the answer that tells us about the length of

472
00:22:50,720 --> 00:22:53,879
Speaker 1: these photons, because red photons have a longer wiggle than

473
00:22:53,920 --> 00:22:56,760
Speaker 1: blue photons, which have a shorter wiggle, And the answer

474
00:22:56,880 --> 00:22:59,199
Speaker 1: is sort of in that direction, but it's not the

475
00:22:59,280 --> 00:23:02,720
Speaker 1: answer of red photon with a very specific energy. It's

476
00:23:02,760 --> 00:23:05,800
Speaker 1: the length of the photon, is not the wavelength of

477
00:23:05,840 --> 00:23:06,479
Speaker 1: that ripple.

478
00:23:06,720 --> 00:23:09,159
Speaker 4: Well, let's talk a little bit about this wavelength. How

479
00:23:09,200 --> 00:23:12,840
Speaker 4: do you measure this wavelength? Like, it's the distance at

480
00:23:12,880 --> 00:23:15,640
Speaker 4: which the ripple repeats itself.

481
00:23:15,960 --> 00:23:18,960
Speaker 1: Yeah, remember we're talking about a ripple in the electromagnetic field.

482
00:23:19,320 --> 00:23:22,439
Speaker 1: What is the electromagnetic field. It's a vector in space,

483
00:23:22,480 --> 00:23:24,919
Speaker 1: which means every point in space has an arrow with

484
00:23:25,000 --> 00:23:27,160
Speaker 1: a direction in it. That's confusing to you. You can

485
00:23:27,200 --> 00:23:29,679
Speaker 1: just pretend it's just a number. Don't worry about the vector.

486
00:23:29,800 --> 00:23:33,280
Speaker 1: And the wavelength tells you when the electromagnetic field returns

487
00:23:33,320 --> 00:23:36,879
Speaker 1: to its original value. Right, So the electromagnetic field is

488
00:23:36,920 --> 00:23:39,040
Speaker 1: pointing up and then it oscillates down, and then it

489
00:23:39,080 --> 00:23:41,520
Speaker 1: oscillates back up again. And this is just like the

490
00:23:41,520 --> 00:23:43,240
Speaker 1: direction of the electric field.

491
00:23:43,040 --> 00:23:45,840
Speaker 4: Meaning like it increases in value. Like if I put

492
00:23:45,840 --> 00:23:48,200
Speaker 4: my finger in front of me, that's a point in space,

493
00:23:48,480 --> 00:23:51,120
Speaker 4: and that point in space has an electromagnet field going

494
00:23:51,119 --> 00:23:52,879
Speaker 4: through it, and that field can certainly have a value

495
00:23:52,880 --> 00:23:53,840
Speaker 4: where I'm pointing my finger.

496
00:23:54,200 --> 00:23:57,040
Speaker 1: The electromagnetic field has a value at every point in space. Yes,

497
00:23:57,080 --> 00:23:58,800
Speaker 1: it has a vector value, which means it has a

498
00:23:58,840 --> 00:24:00,280
Speaker 1: direction and a line length.

499
00:24:00,560 --> 00:24:02,960
Speaker 4: H right, But we're just talking about value, and so

500
00:24:03,119 --> 00:24:05,960
Speaker 4: like where I'm pointing, my finger can suddenly go up

501
00:24:05,960 --> 00:24:08,560
Speaker 4: in value, like it can be zero right now, zero zero,

502
00:24:08,640 --> 00:24:09,920
Speaker 4: but suddenly it can go up to ten.

503
00:24:10,080 --> 00:24:12,159
Speaker 1: Yeah, exactly. It can change with time.

504
00:24:12,800 --> 00:24:15,000
Speaker 4: And then it can go back down to zero. And

505
00:24:15,040 --> 00:24:15,760
Speaker 4: that's a ripple.

506
00:24:15,920 --> 00:24:17,760
Speaker 1: And if you want to think about the wavelength, you

507
00:24:17,760 --> 00:24:20,119
Speaker 1: know you have your finger at one point and the

508
00:24:20,160 --> 00:24:23,240
Speaker 1: electromagnetic field has a value there. If there's a photon

509
00:24:23,359 --> 00:24:25,960
Speaker 1: moving through space there, then if you could put another

510
00:24:26,040 --> 00:24:28,600
Speaker 1: finger somewhere else, you can ask where do I have

511
00:24:28,640 --> 00:24:30,440
Speaker 1: to put my other finger so it has the same

512
00:24:30,520 --> 00:24:32,880
Speaker 1: value as my first finger. And that's what the wavelength

513
00:24:32,920 --> 00:24:35,400
Speaker 1: is telling us. Because the wavelength tells us the electromagnetic

514
00:24:35,440 --> 00:24:37,680
Speaker 1: field goes up and then down, where does it come

515
00:24:37,720 --> 00:24:41,400
Speaker 1: back to its original value? That's the wavelength. For blue photons,

516
00:24:41,440 --> 00:24:43,760
Speaker 1: your two fingers be closer together, and for red photons,

517
00:24:43,760 --> 00:24:45,080
Speaker 1: your fingers would be further apart.

518
00:24:45,480 --> 00:24:48,439
Speaker 4: And so light is like the value going up in

519
00:24:48,480 --> 00:24:50,439
Speaker 4: one of my fingers and down and then go up

520
00:24:50,480 --> 00:24:53,080
Speaker 4: and down in my other finger. But it only happens

521
00:24:53,119 --> 00:24:56,879
Speaker 4: once for each photon, like a photon passing through is

522
00:24:56,960 --> 00:24:58,800
Speaker 4: just a one wave, right.

523
00:24:58,920 --> 00:25:01,159
Speaker 1: I understand why that's fue but that's not actually what

524
00:25:01,240 --> 00:25:04,360
Speaker 1: one photon is. And this is going to sound like nonsense,

525
00:25:04,440 --> 00:25:06,919
Speaker 1: But a single photon of specific energy, like if you

526
00:25:06,960 --> 00:25:10,960
Speaker 1: say exactly what the wavelength is, that photon actually has

527
00:25:11,000 --> 00:25:15,760
Speaker 1: an infinite size in space, like that photon exists everywhere

528
00:25:15,760 --> 00:25:17,800
Speaker 1: in the universe. I told you it was going to

529
00:25:17,840 --> 00:25:21,639
Speaker 1: sound like nonsense. Tried to warn you.

530
00:25:23,040 --> 00:25:24,800
Speaker 4: Well, it sounds like we're going to get a pretty

531
00:25:24,800 --> 00:25:27,679
Speaker 4: deep into this, So why don't we take a quick break,

532
00:25:27,800 --> 00:25:30,120
Speaker 4: and then when we come back, we'll dig into what

533
00:25:30,160 --> 00:25:33,480
Speaker 4: it means for light to be everywhere all at once.

534
00:25:33,760 --> 00:25:35,920
Speaker 4: So let's do that, But first let's take a quick break.

535
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586
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603
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Speaker 4: All right, we're talking about light and how long light is,

604
00:29:21,920 --> 00:29:24,720
Speaker 4: and Daniel, you just kind of blew our minds here

605
00:29:24,800 --> 00:29:27,440
Speaker 4: and said that light can be everywhere, all at once,

606
00:29:28,000 --> 00:29:31,200
Speaker 4: which is the name of a great movie which coincidentally

607
00:29:31,200 --> 00:29:32,600
Speaker 4: involved hot dog Fingers.

608
00:29:33,160 --> 00:29:36,240
Speaker 1: That's true, not coincidentally, man, that was the long term

609
00:29:36,360 --> 00:29:37,920
Speaker 1: plan for this whole joke. I was going to bring

610
00:29:38,000 --> 00:29:38,360
Speaker 1: up back.

611
00:29:39,720 --> 00:29:43,960
Speaker 4: Yes, it was just a giant plug for a movie.

612
00:29:44,760 --> 00:29:46,640
Speaker 1: Eight twenty four. Send us some free passes.

613
00:29:47,080 --> 00:29:50,160
Speaker 4: Yeah, there you go. So we're talking about like a

614
00:29:50,200 --> 00:29:53,280
Speaker 4: photon is a giant bubble that emanates from a light source.

615
00:29:54,000 --> 00:29:56,960
Speaker 4: It's everywhere, all at once, in all directions until something

616
00:29:57,040 --> 00:29:59,920
Speaker 4: hits it. But then if I'm the person that it hit,

617
00:30:00,760 --> 00:30:03,160
Speaker 4: you're saying, it's not something that just washes over me.

618
00:30:03,400 --> 00:30:05,080
Speaker 1: Yes, So we're going to talk about the length of

619
00:30:05,120 --> 00:30:07,760
Speaker 1: a photon, then we have to know something about the

620
00:30:07,880 --> 00:30:10,280
Speaker 1: energy of the photon. And you might think, hold on,

621
00:30:10,360 --> 00:30:13,640
Speaker 1: isn't he changing the subject. Remember that for quantum objects,

622
00:30:13,960 --> 00:30:16,960
Speaker 1: their location and the uncertainty in their location, how well

623
00:30:17,000 --> 00:30:20,680
Speaker 1: you can pin that down is intimately connected with their energy.

624
00:30:20,920 --> 00:30:24,080
Speaker 1: The Heisenberg uncertainty principle tells us that you can't know

625
00:30:24,200 --> 00:30:27,560
Speaker 1: perfectly well the energy of an object or its momentum

626
00:30:27,720 --> 00:30:31,880
Speaker 1: nearly equivalently and its location. And so for a photon,

627
00:30:32,280 --> 00:30:34,880
Speaker 1: if you know exactly its energy, if I have a laser,

628
00:30:34,920 --> 00:30:38,840
Speaker 1: for example, which always puts out photons at one wavelength,

629
00:30:38,840 --> 00:30:41,600
Speaker 1: and I know it exactly those photons because we specify

630
00:30:41,640 --> 00:30:44,640
Speaker 1: their energy precisely, that means we can't know anything about

631
00:30:44,680 --> 00:30:47,800
Speaker 1: their location. And so like the quantum field theory version

632
00:30:47,840 --> 00:30:51,040
Speaker 1: says that the whole universe, the electromagnetic fields of the

633
00:30:51,120 --> 00:30:56,120
Speaker 1: whole universe, has that photon in it. It's oscillating simultaneously everywhere.

634
00:30:56,600 --> 00:30:58,640
Speaker 4: And now I guess it's getting kind of harry because

635
00:30:58,680 --> 00:31:01,120
Speaker 4: we just talked about how like a food is a ripple,

636
00:31:01,240 --> 00:31:03,520
Speaker 4: like a bubble that emanates from a star or a

637
00:31:03,640 --> 00:31:06,640
Speaker 4: light source, right, and so that bubble is getting bigger

638
00:31:06,640 --> 00:31:09,840
Speaker 4: and bigger until it hits something. But that bubble kind

639
00:31:09,840 --> 00:31:13,160
Speaker 4: of has a location, right, It's on the surface of

640
00:31:13,200 --> 00:31:15,080
Speaker 4: that bubble. So how can it be on the surface

641
00:31:15,120 --> 00:31:17,200
Speaker 4: of the bubble and also everywhere all at once?

642
00:31:17,360 --> 00:31:20,680
Speaker 1: Yeah, great question. The answer is in the uncertainty of

643
00:31:20,720 --> 00:31:24,760
Speaker 1: its energy. If a star really could produce photons of

644
00:31:24,840 --> 00:31:28,360
Speaker 1: exactly one energy, then they would be everywhere all at once.

645
00:31:28,680 --> 00:31:31,840
Speaker 1: But that's totally unphysical. You can't have something weighed everywhere

646
00:31:31,880 --> 00:31:34,640
Speaker 1: in the universe all at once, right, That like violates

647
00:31:34,640 --> 00:31:37,600
Speaker 1: all sorts of principles of relativity. Quantum mechanics and relativity

648
00:31:37,680 --> 00:31:40,000
Speaker 1: sometimes take a little bit of conceptual glue to stick together.

649
00:31:40,520 --> 00:31:42,880
Speaker 1: The way to resolve it is to realize, well, there

650
00:31:42,920 --> 00:31:45,760
Speaker 1: are no such photons in the universe. Nothing is actually

651
00:31:45,760 --> 00:31:50,160
Speaker 1: made with that exact, super specific energy. In reality, photons

652
00:31:50,200 --> 00:31:52,960
Speaker 1: always have an uncertainty in their energy. A star is

653
00:31:53,040 --> 00:31:56,640
Speaker 1: never making exact energy photons. There's always a spread. Even

654
00:31:56,720 --> 00:31:59,400
Speaker 1: lasers that you think of as having one specific energy,

655
00:31:59,480 --> 00:32:03,560
Speaker 1: there's always uncertainty. Even atoms when they're emitting photons between

656
00:32:03,680 --> 00:32:06,520
Speaker 1: energy levels, there's always a little bit of fuzziness there.

657
00:32:06,880 --> 00:32:09,920
Speaker 1: So there's an uncertainty in the photon's energy, and the

658
00:32:09,960 --> 00:32:12,840
Speaker 1: more uncertainty in the energy, the more constrained the photon

659
00:32:12,880 --> 00:32:15,280
Speaker 1: can be in space. So what's coming out of the

660
00:32:15,320 --> 00:32:18,400
Speaker 1: star is a ripple, and it's localized in space because

661
00:32:18,440 --> 00:32:20,320
Speaker 1: there's an uncertainty in its energy.

662
00:32:20,520 --> 00:32:23,440
Speaker 4: Is the time at which it gets made also uncertain

663
00:32:23,960 --> 00:32:26,040
Speaker 4: or is that something we're allowed to know for sure,

664
00:32:26,680 --> 00:32:29,160
Speaker 4: because then you know, we know exactly when it was emanated,

665
00:32:29,200 --> 00:32:30,920
Speaker 4: and we know the speed of light never changes, then

666
00:32:30,960 --> 00:32:33,160
Speaker 4: we know sort of exactly where that bubble is.

667
00:32:33,560 --> 00:32:36,480
Speaker 1: Yeah, there's a Heisenberg and certainty relationship between uncertainty and

668
00:32:36,600 --> 00:32:39,280
Speaker 1: energy and uncertainty in time. So now you can't know

669
00:32:39,360 --> 00:32:40,920
Speaker 1: that exactly either either.

670
00:32:41,640 --> 00:32:43,800
Speaker 4: So there's three things or they're all tied together.

671
00:32:43,880 --> 00:32:46,560
Speaker 1: They're all tied together. There's location and momentum, and then

672
00:32:46,560 --> 00:32:49,400
Speaker 1: there's energy and time. Those are two separate Heisenberg and

673
00:32:49,400 --> 00:32:52,880
Speaker 1: certainty relationships. But for a photon, momentum and energy are

674
00:32:52,960 --> 00:32:56,040
Speaker 1: the same thing. They're only different from massive particles, and

675
00:32:56,120 --> 00:32:58,640
Speaker 1: so they really are all three things tied together by

676
00:32:58,680 --> 00:33:01,640
Speaker 1: this fuzziness. So it's the uncertainty. The fact that we

677
00:33:01,680 --> 00:33:05,640
Speaker 1: can never have pure, single energy photons means we always

678
00:33:05,680 --> 00:33:08,400
Speaker 1: get these packets, these blobs. It's like, well, maybe this

679
00:33:08,400 --> 00:33:10,920
Speaker 1: photon is this energy, maybe it has that energy, maybe

680
00:33:10,920 --> 00:33:14,120
Speaker 1: it has this other energy, And that's what defines the

681
00:33:14,280 --> 00:33:17,320
Speaker 1: length of a photon. It's really a packet of this uncertainty,

682
00:33:17,720 --> 00:33:20,240
Speaker 1: and the amount of energy uncertainty in that packet gives

683
00:33:20,320 --> 00:33:23,000
Speaker 1: us the length of the uncertainty in its location.

684
00:33:23,440 --> 00:33:25,960
Speaker 4: Meaning like the bubble that emanates from the star or

685
00:33:26,080 --> 00:33:29,240
Speaker 4: light source is not like a hard bubble, like a

686
00:33:29,440 --> 00:33:32,800
Speaker 4: real like soap bubble, but it's actually more like an expanding,

687
00:33:32,840 --> 00:33:33,520
Speaker 4: fuzzy cloud.

688
00:33:33,680 --> 00:33:34,880
Speaker 1: Way I think about it is sort of like a

689
00:33:34,880 --> 00:33:37,760
Speaker 1: little wave packet. You've got lots of frequencies together. They

690
00:33:37,760 --> 00:33:40,920
Speaker 1: add a subject that they interfere positively and negatively to

691
00:33:40,960 --> 00:33:43,840
Speaker 1: give you this wave packet that's moving through space. For

692
00:33:43,880 --> 00:33:46,000
Speaker 1: those of you out there who know like signal analysis

693
00:33:46,040 --> 00:33:49,320
Speaker 1: or Fourier analysis, you know that like a single momentum

694
00:33:49,320 --> 00:33:51,440
Speaker 1: corresponds to an infinite extent in space. But if you

695
00:33:51,440 --> 00:33:53,920
Speaker 1: add up a bunch of different momentum and different frequencies,

696
00:33:54,120 --> 00:33:56,440
Speaker 1: you can make any sort of shape you want in space.

697
00:33:56,880 --> 00:33:59,040
Speaker 4: Right, But then I feel like this, all this uncertainty

698
00:33:59,080 --> 00:34:02,000
Speaker 4: comes from that we don't know when it was made,

699
00:34:02,200 --> 00:34:04,200
Speaker 4: this photon, we don't know how it was made. We

700
00:34:04,200 --> 00:34:06,360
Speaker 4: don't know how energy it had when it was made.

701
00:34:06,520 --> 00:34:08,480
Speaker 4: But once we detect it, we sort of do know

702
00:34:08,520 --> 00:34:09,080
Speaker 4: all these things.

703
00:34:09,160 --> 00:34:11,320
Speaker 1: Right, Well, we never measure an energy of a photon

704
00:34:11,440 --> 00:34:14,200
Speaker 1: exactly right. You can never precisely measure the energy of

705
00:34:14,200 --> 00:34:16,279
Speaker 1: a photon. How do you measure it anyway? You have

706
00:34:16,360 --> 00:34:19,279
Speaker 1: it impact some device, and that device has some mechanism

707
00:34:19,320 --> 00:34:21,879
Speaker 1: inside of it, and you read that number off. There's

708
00:34:21,920 --> 00:34:24,919
Speaker 1: always uncertainty, not just because the mechanism is something cheap

709
00:34:24,960 --> 00:34:27,560
Speaker 1: you bought off Amazon, but because there is an inherent

710
00:34:27,640 --> 00:34:30,280
Speaker 1: quantum uncertainty in the measurement itself.

711
00:34:30,640 --> 00:34:32,799
Speaker 4: There's a little bit of uncertainty, sure, But like when

712
00:34:32,800 --> 00:34:34,640
Speaker 4: I'm looking at a hot dog, it doesn't suddenly turn

713
00:34:34,760 --> 00:34:37,440
Speaker 4: yellow or purple, or hopefully it doesn't turn yellow and

714
00:34:37,480 --> 00:34:38,480
Speaker 4: purple as I look at it.

715
00:34:38,520 --> 00:34:40,640
Speaker 1: The hot dog is not a laser, and it's not

716
00:34:40,680 --> 00:34:44,520
Speaker 1: an idealized laser. It's emitting a spread of colors, and

717
00:34:44,600 --> 00:34:47,080
Speaker 1: so every photon that comes out of that hot dog

718
00:34:47,120 --> 00:34:48,960
Speaker 1: has the possibility to be a little greener or a

719
00:34:48,960 --> 00:34:51,960
Speaker 1: little redder, or a little bluer. There's the fussiness in

720
00:34:52,000 --> 00:34:54,040
Speaker 1: every single photon that comes out of the hot dog.

721
00:34:54,960 --> 00:34:56,920
Speaker 4: But once I measure it, don't I know exactly what

722
00:34:57,000 --> 00:34:57,919
Speaker 4: frequency it had.

723
00:34:58,080 --> 00:35:00,279
Speaker 1: There's still an uncertainty when you measure it, So yeah,

724
00:35:00,280 --> 00:35:02,200
Speaker 1: it does collapse some of that uncertainly. I mean you

725
00:35:02,200 --> 00:35:04,200
Speaker 1: see a blue photon, or you see a red photon,

726
00:35:04,280 --> 00:35:06,759
Speaker 1: or you see a green photon, but again still never

727
00:35:06,840 --> 00:35:07,719
Speaker 1: super precisely.

728
00:35:07,920 --> 00:35:11,080
Speaker 4: What if we had a perfect measurement device and we

729
00:35:11,120 --> 00:35:14,840
Speaker 4: can collapse it perfectly, would we know it's exact frequency?

730
00:35:15,280 --> 00:35:17,120
Speaker 1: I think such a device would have to be the

731
00:35:17,160 --> 00:35:19,160
Speaker 1: size of the universe, and so then you would know

732
00:35:19,200 --> 00:35:20,359
Speaker 1: nothing about where it was.

733
00:35:20,800 --> 00:35:21,600
Speaker 4: Can you explain that?

734
00:35:21,680 --> 00:35:24,080
Speaker 1: First of all, a device that measures anything exactly is

735
00:35:24,160 --> 00:35:27,080
Speaker 1: just impossible. Right, You can take the limit of something

736
00:35:27,160 --> 00:35:29,520
Speaker 1: you can start with, like what's the most precise measurement

737
00:35:29,520 --> 00:35:31,399
Speaker 1: device I can have, and then try to think about

738
00:35:31,440 --> 00:35:33,759
Speaker 1: taking the limit of it to perfect precision. Or to

739
00:35:33,800 --> 00:35:36,240
Speaker 1: measure something very precisely that has a lot of energy,

740
00:35:36,360 --> 00:35:38,080
Speaker 1: you need to have an object which you can interact

741
00:35:38,239 --> 00:35:41,279
Speaker 1: with photons of very different wavelengths. Right, wavelengths can be

742
00:35:41,360 --> 00:35:43,839
Speaker 1: very very short for very high energy, or very very

743
00:35:43,960 --> 00:35:46,840
Speaker 1: large for very low energy, and so measuring things that

744
00:35:46,880 --> 00:35:49,960
Speaker 1: are very very large requires large objects. Like you want

745
00:35:50,000 --> 00:35:53,280
Speaker 1: to receive radio waves, you need a very big antenna.

746
00:35:53,640 --> 00:35:56,799
Speaker 1: You want to receive microwaves, you need very small antennas.

747
00:35:57,000 --> 00:35:59,520
Speaker 1: So you want to measure something super precisely. That can

748
00:35:59,560 --> 00:36:02,200
Speaker 1: be of any wavelength. You're going to need essentially an

749
00:36:02,200 --> 00:36:03,719
Speaker 1: antenna to size of the universe.

750
00:36:04,160 --> 00:36:06,799
Speaker 4: Oh boy, that's a that would be a very big

751
00:36:06,840 --> 00:36:07,279
Speaker 4: hot dog.

752
00:36:08,120 --> 00:36:09,359
Speaker 1: It costs more than a hot dog.

753
00:36:09,400 --> 00:36:11,520
Speaker 4: All right, But maybe let's give up on perfection and

754
00:36:11,560 --> 00:36:14,840
Speaker 4: say that you know, I measure a photon coming for

755
00:36:15,000 --> 00:36:17,320
Speaker 4: my hot dog, and I see that it's red plus

756
00:36:17,400 --> 00:36:19,920
Speaker 4: or minus point one hurts. That's a pretty good measurement

757
00:36:19,960 --> 00:36:23,000
Speaker 4: of its wavelength. No, we can get to that point, right.

758
00:36:23,200 --> 00:36:26,279
Speaker 1: Yeah, you can make fairly precise measurements of individual photons. Yes,

759
00:36:26,520 --> 00:36:30,720
Speaker 1: you can also produce sources of photons that are fairly pure,

760
00:36:30,760 --> 00:36:33,640
Speaker 1: that are very tight bands of energy ranges. Yeah.

761
00:36:33,719 --> 00:36:36,000
Speaker 4: So then if I know the wavelength of the photon,

762
00:36:36,120 --> 00:36:38,319
Speaker 4: doesn't that give me a sense of how long it is.

763
00:36:38,760 --> 00:36:40,680
Speaker 1: If you know the wavelength of the photon and you

764
00:36:40,719 --> 00:36:44,000
Speaker 1: know the uncertainty in that wavelength, then yes, that defines

765
00:36:44,080 --> 00:36:47,560
Speaker 1: the length of this wave packet, all these possible photons

766
00:36:47,560 --> 00:36:50,320
Speaker 1: that are flying through space together. It's a little unsatisfying

767
00:36:50,320 --> 00:36:53,160
Speaker 1: as an answer because it's not something inherent to the photon.

768
00:36:53,680 --> 00:36:55,879
Speaker 1: It's like you got a bunch of these blobs all

769
00:36:55,920 --> 00:36:58,960
Speaker 1: moving together. Through the universe. The answer how long is

770
00:36:59,000 --> 00:37:02,239
Speaker 1: the photon depends sort of like on your uncertainty in

771
00:37:02,280 --> 00:37:04,640
Speaker 1: your knowledge of its energy. So I think it's accurate

772
00:37:04,640 --> 00:37:06,279
Speaker 1: from a quantum mechanical point of view, but it's very

773
00:37:06,360 --> 00:37:09,320
Speaker 1: unsatisfying from a philosophical point of view because it feels

774
00:37:09,360 --> 00:37:12,520
Speaker 1: like the photon should have a length that's just inherent

775
00:37:12,640 --> 00:37:15,040
Speaker 1: to it. It shouldn't depend on like your measurement of it

776
00:37:15,440 --> 00:37:16,480
Speaker 1: or your knowledge of it.

777
00:37:16,760 --> 00:37:19,400
Speaker 4: But it doesn't sort of depend on my knowledge or

778
00:37:19,520 --> 00:37:21,400
Speaker 4: measurement of it, right, Like if I measured and I

779
00:37:21,480 --> 00:37:23,799
Speaker 4: measured the red plus or minus point what hurts, and

780
00:37:23,880 --> 00:37:25,759
Speaker 4: somebody else measureed would have measured it, they would have

781
00:37:25,880 --> 00:37:27,880
Speaker 4: probably gone the same result, right, Yeah.

782
00:37:27,760 --> 00:37:30,319
Speaker 1: It doesn't depend on your particular knowledge of it. There

783
00:37:30,360 --> 00:37:33,640
Speaker 1: is an inherent uncertainty in it because it's a quantum state,

784
00:37:34,000 --> 00:37:36,400
Speaker 1: and to me that's a little bit unsatisfying. The idea

785
00:37:36,440 --> 00:37:38,520
Speaker 1: that it doesn't have a fixed length, or that it's

786
00:37:38,640 --> 00:37:42,160
Speaker 1: length somehow depends on that uncertainty. To answer your specific question,

787
00:37:42,560 --> 00:37:45,080
Speaker 1: if there's uncertainty, it means that no two people would

788
00:37:45,080 --> 00:37:48,279
Speaker 1: make exactly the same measurement. They'd be probably consistent, you know,

789
00:37:48,360 --> 00:37:51,719
Speaker 1: within the uncertainties, but they wouldn't get exactly the same answer.

790
00:37:51,560 --> 00:37:55,279
Speaker 4: Right, right, We would all see it as vapor hotdog, right,

791
00:37:55,320 --> 00:37:57,600
Speaker 4: and so couldn't you. I mean, I know we're not

792
00:37:57,760 --> 00:37:59,959
Speaker 4: we can't ever get super preciped, but we can probably

793
00:38:00,120 --> 00:38:02,359
Speaker 4: say you and I can both agree that, yeah, that's

794
00:38:02,480 --> 00:38:04,600
Speaker 4: vapor hot dog and not miss the hot dog.

795
00:38:05,040 --> 00:38:07,440
Speaker 1: Yeah. And I'm not saying photons don't have a length.

796
00:38:07,480 --> 00:38:09,520
Speaker 1: I'm just saying that the length depends not just on

797
00:38:09,600 --> 00:38:12,759
Speaker 1: the wavelength of light, but on the uncertainty on the wavelength,

798
00:38:12,800 --> 00:38:14,560
Speaker 1: because in the end they're quantum objects.

799
00:38:14,840 --> 00:38:16,920
Speaker 4: Right, So then can we answer the question of how

800
00:38:16,920 --> 00:38:20,040
Speaker 4: long a photon is or was? Or is it that

801
00:38:20,080 --> 00:38:22,480
Speaker 4: we can only answer what the length of a footon was?

802
00:38:22,880 --> 00:38:25,280
Speaker 1: We can answer the question if you know the energy

803
00:38:25,360 --> 00:38:29,479
Speaker 1: and the uncertainty on that energy that determines the length

804
00:38:29,480 --> 00:38:31,560
Speaker 1: of the photon in this sense of length.

805
00:38:31,800 --> 00:38:33,880
Speaker 4: So that's good, right, possible?

806
00:38:35,080 --> 00:38:35,319
Speaker 1: Yeah?

807
00:38:35,600 --> 00:38:36,759
Speaker 4: Are you saying it's impossible?

808
00:38:36,800 --> 00:38:38,080
Speaker 1: No? No, I'm saying it's possible.

809
00:38:38,239 --> 00:38:40,920
Speaker 4: All right, So then that's the quantum field theory version

810
00:38:41,000 --> 00:38:43,600
Speaker 4: of a photon. You said that how long a footon is?

811
00:38:43,600 --> 00:38:46,040
Speaker 4: It depends on how you look at it. So then

812
00:38:46,120 --> 00:38:48,920
Speaker 4: if we assume light is a particle, can we measure

813
00:38:49,200 --> 00:38:50,360
Speaker 4: the length of that particle.

814
00:38:50,480 --> 00:38:52,480
Speaker 1: Yeah, the answer does depend a little bit on how

815
00:38:52,520 --> 00:38:54,399
Speaker 1: you look at it, because in some cases you don't

816
00:38:54,440 --> 00:38:56,879
Speaker 1: care about the length of photon. You don't care about

817
00:38:56,880 --> 00:38:59,440
Speaker 1: these details, and you don't care about the size of anything.

818
00:39:00,000 --> 00:39:01,719
Speaker 1: It's really really small, So you could just treat them

819
00:39:01,719 --> 00:39:04,760
Speaker 1: as zero point particles. And we talk on the podcast

820
00:39:04,760 --> 00:39:06,840
Speaker 1: a lot about how like electrons have no size and

821
00:39:06,920 --> 00:39:09,520
Speaker 1: quarks have no size, And the answer to that really

822
00:39:09,600 --> 00:39:11,440
Speaker 1: is they have no size that we measure or in

823
00:39:11,480 --> 00:39:14,040
Speaker 1: some cases that we care about, and so we can

824
00:39:14,080 --> 00:39:16,560
Speaker 1: treat them as if they're zero point particles with no

825
00:39:16,719 --> 00:39:19,279
Speaker 1: length to them. For some problems where it doesn't really

826
00:39:19,320 --> 00:39:21,399
Speaker 1: matter if they have length, you know, like when they're

827
00:39:21,480 --> 00:39:23,319
Speaker 1: hitting a screen, we didn't really care how long it

828
00:39:23,320 --> 00:39:25,480
Speaker 1: took to hit the screen or what their extent was.

829
00:39:25,520 --> 00:39:27,239
Speaker 1: As they were flying through space, we can just treat

830
00:39:27,280 --> 00:39:30,279
Speaker 1: them as if they were tiny, zero point particles, and

831
00:39:30,320 --> 00:39:33,440
Speaker 1: so that picture is useful for answering some kinds of questions,

832
00:39:33,480 --> 00:39:35,840
Speaker 1: just the same way we can think about classical waves

833
00:39:36,280 --> 00:39:37,240
Speaker 1: moving through space.

834
00:39:37,480 --> 00:39:39,520
Speaker 4: Well, I feel like it's sort of useful. Maybe I

835
00:39:39,560 --> 00:39:43,320
Speaker 4: wonder in some applications, like for example, let's say photons

836
00:39:43,320 --> 00:39:46,320
Speaker 4: are super duper long, they're the size of a planet

837
00:39:46,400 --> 00:39:50,960
Speaker 4: size hobo. Then when that photon hits me, it's going

838
00:39:50,960 --> 00:39:54,319
Speaker 4: to take a long time, you know, minute for me

839
00:39:54,400 --> 00:39:57,000
Speaker 4: to feel the photon all the way, as opposed to

840
00:39:57,560 --> 00:40:00,520
Speaker 4: if a photon is just an infinitely small point particle,

841
00:40:00,600 --> 00:40:03,680
Speaker 4: then I'm going to feel the photon instantly. So is

842
00:40:03,680 --> 00:40:06,560
Speaker 4: there sort of a time at which I get to

843
00:40:06,680 --> 00:40:09,480
Speaker 4: feel photons or is it relevant or what are the

844
00:40:09,480 --> 00:40:10,520
Speaker 4: hot dog dynamics here?

845
00:40:10,640 --> 00:40:12,880
Speaker 1: Yeah, so that's a great question, and to answer that question,

846
00:40:13,000 --> 00:40:15,239
Speaker 1: you definitely need to use the quantum field theory version

847
00:40:15,239 --> 00:40:16,799
Speaker 1: of a hot dog. You need to think about the

848
00:40:16,840 --> 00:40:20,640
Speaker 1: probability of photon having various wavelengths and those wavelengths overlapping

849
00:40:20,640 --> 00:40:23,640
Speaker 1: with you. When that probability wave packet overlaps with you,

850
00:40:23,680 --> 00:40:26,440
Speaker 1: and when it doesn't overlap with you, when it does collapse,

851
00:40:26,480 --> 00:40:29,520
Speaker 1: though it collapses instantly across the entire photon, you can't

852
00:40:29,560 --> 00:40:32,120
Speaker 1: feel like part of a photon. There is no part

853
00:40:32,120 --> 00:40:34,719
Speaker 1: of a photon, right. Photons are quantized.

854
00:40:34,239 --> 00:40:37,200
Speaker 4: Like when I feel a photon, it's instantaneous, is what

855
00:40:37,200 --> 00:40:38,080
Speaker 4: you're saying, yeah.

856
00:40:37,920 --> 00:40:41,000
Speaker 1: You feel the whole photon or no photons exactly or

857
00:40:41,080 --> 00:40:42,200
Speaker 1: so or seven photons?

858
00:40:42,400 --> 00:40:44,360
Speaker 4: What if it has like super duper big waves, like

859
00:40:44,360 --> 00:40:48,239
Speaker 4: we've talked about light waves having a wavelength the size

860
00:40:48,239 --> 00:40:51,320
Speaker 4: of a galaxy, for example, Like we feel those instantly

861
00:40:51,480 --> 00:40:53,120
Speaker 4: or do we need to wait a long time to

862
00:40:53,160 --> 00:40:53,600
Speaker 4: feel them?

863
00:40:53,760 --> 00:40:56,359
Speaker 1: Yeah, you either feel them or you don't. Right, there's

864
00:40:56,360 --> 00:40:59,560
Speaker 1: no time at which you're like cruing a photon.

865
00:41:00,120 --> 00:41:02,200
Speaker 4: Right, but the ripple of it isn't the ripple of

866
00:41:02,239 --> 00:41:04,040
Speaker 4: it in space long too?

867
00:41:04,280 --> 00:41:07,600
Speaker 1: Or what? Yeah, so photons could be really really long, right,

868
00:41:08,000 --> 00:41:10,400
Speaker 1: if you have a photon with really long wavelengths and

869
00:41:10,640 --> 00:41:13,680
Speaker 1: really large uncertainty, those photons could be the size of

870
00:41:13,719 --> 00:41:17,600
Speaker 1: a galaxy, absolutely, and that photon could interact with something

871
00:41:17,640 --> 00:41:20,360
Speaker 1: within the galaxy. Right, But then the whole photon collapses

872
00:41:20,400 --> 00:41:22,040
Speaker 1: all at once, just the same way that a pair

873
00:41:22,040 --> 00:41:25,040
Speaker 1: of entangled particles you shoot off in opposite directions, they're

874
00:41:25,040 --> 00:41:27,800
Speaker 1: really still part of one big quantum state. You measure

875
00:41:27,840 --> 00:41:30,560
Speaker 1: one on one side of the galaxy. The whole quantum

876
00:41:30,560 --> 00:41:34,160
Speaker 1: state collapses at once because it's really just one quantum state.

877
00:41:34,719 --> 00:41:38,160
Speaker 1: Same way for this galaxy size hot dog size photon

878
00:41:38,480 --> 00:41:40,080
Speaker 1: if it's really as big as the galaxy. If it

879
00:41:40,080 --> 00:41:43,399
Speaker 1: interacts anywhere, then the whole quantum state collapses at once.

880
00:41:44,520 --> 00:41:47,719
Speaker 4: So like you can think of it as having a

881
00:41:47,760 --> 00:41:49,799
Speaker 4: giant photon the size of a galaxy. But once I

882
00:41:49,840 --> 00:41:52,400
Speaker 4: catch it, it's really just a little tiny point particle.

883
00:41:52,680 --> 00:41:55,080
Speaker 1: Yeah, exactly. It interacts in that one spot, and you

884
00:41:55,120 --> 00:41:58,279
Speaker 1: might think, hold on a second, doesn't this violate special relativity?

885
00:41:58,280 --> 00:42:00,880
Speaker 1: And it feels like, you know, that might allow you

886
00:42:00,920 --> 00:42:03,440
Speaker 1: to send messages faster than time. And there is a

887
00:42:03,480 --> 00:42:07,719
Speaker 1: real subtlety there with how quantum theory and relativity interact.

888
00:42:07,880 --> 00:42:09,960
Speaker 1: We talked about in the podcast. It's the reason why

889
00:42:10,000 --> 00:42:13,600
Speaker 1: we have anti particles. Antiparticles patch all this up with

890
00:42:13,680 --> 00:42:16,440
Speaker 1: all these negative probabilities and make sure that everything is

891
00:42:16,480 --> 00:42:19,239
Speaker 1: following all the rules. Check out our episode on why

892
00:42:19,320 --> 00:42:22,320
Speaker 1: quantum mechanics and special relativity require anti particles.

893
00:42:22,320 --> 00:42:24,960
Speaker 4: Well, I feel like you're kind of making a judgment

894
00:42:25,080 --> 00:42:28,400
Speaker 4: on the particle view of light. You're saying it's not

895
00:42:28,520 --> 00:42:32,719
Speaker 4: really a particle or you ultimately have to kind of

896
00:42:32,719 --> 00:42:35,759
Speaker 4: go back to quantum theory to talk about light. We

897
00:42:35,800 --> 00:42:37,960
Speaker 4: can't stay in the particle view at for very long.

898
00:42:38,520 --> 00:42:42,160
Speaker 1: I'm definitely using this field picture here, thinking about light

899
00:42:42,280 --> 00:42:45,719
Speaker 1: as ripples in an electromagnetic field, and that I think

900
00:42:45,760 --> 00:42:48,480
Speaker 1: is the most mainstream view, But there's definitely a chunk

901
00:42:48,560 --> 00:42:51,520
Speaker 1: of particle theorists who think in the particle picture, and

902
00:42:51,560 --> 00:42:54,799
Speaker 1: you absolutely can you can replace the field with an

903
00:42:54,800 --> 00:42:58,000
Speaker 1: infinite number of virtual particles and do all the same

904
00:42:58,080 --> 00:43:01,120
Speaker 1: calculations and it all works. So what I've described is

905
00:43:01,120 --> 00:43:03,560
Speaker 1: the field picture of light as a ripple in this

906
00:43:03,640 --> 00:43:06,680
Speaker 1: electromagnetic field. You can also think about these probabilities in

907
00:43:06,760 --> 00:43:09,879
Speaker 1: terms of like these virtual particles, which are conceptually kind

908
00:43:09,880 --> 00:43:13,200
Speaker 1: of slippery because they're not really particles or really just probabilities.

909
00:43:13,280 --> 00:43:15,359
Speaker 1: But you can think about all these kind of interactions

910
00:43:15,360 --> 00:43:17,800
Speaker 1: and these transmissions in terms of an infinite number of

911
00:43:17,880 --> 00:43:20,239
Speaker 1: virtual particles, if you like. Though I think it's a

912
00:43:20,239 --> 00:43:22,240
Speaker 1: lot more awkward, especially in this case.

913
00:43:22,480 --> 00:43:24,879
Speaker 4: Well awkward is a relative tern Dane. They might say

914
00:43:24,920 --> 00:43:25,719
Speaker 4: the same thing about you.

915
00:43:26,160 --> 00:43:29,040
Speaker 1: Yeah, absolutely, and it's a little bit subjective. Mathematically, both

916
00:43:29,080 --> 00:43:31,560
Speaker 1: pictures work, so I'm trying not to make a judgment

917
00:43:31,800 --> 00:43:34,760
Speaker 1: on what is the best picture of the quantum universe.

918
00:43:34,960 --> 00:43:37,160
Speaker 1: There's a particle people and the fields people, and both

919
00:43:37,200 --> 00:43:40,360
Speaker 1: of them have strong cases conceptually, for me, the fields

920
00:43:40,400 --> 00:43:42,560
Speaker 1: picture is more intuitive, though that doesn't mean that it's

921
00:43:42,640 --> 00:43:43,520
Speaker 1: right right.

922
00:43:43,600 --> 00:43:46,640
Speaker 4: So then let's say we replace you, Daniel. We call

923
00:43:46,719 --> 00:43:50,399
Speaker 4: this podcast Mark and Jorge explain the universe, and Mark

924
00:43:50,440 --> 00:43:53,759
Speaker 4: happens to be a particle person that sees the world

925
00:43:53,800 --> 00:43:56,439
Speaker 4: as particles. How would they answer the question how long

926
00:43:56,560 --> 00:43:57,160
Speaker 4: is a particle?

927
00:43:57,320 --> 00:43:59,799
Speaker 1: Even in the particle picture of the universe, where there

928
00:43:59,840 --> 00:44:01,879
Speaker 1: are or no fields, there is just an infinite number

929
00:44:01,920 --> 00:44:04,400
Speaker 1: of real particles and an infint number of virtual particles

930
00:44:04,440 --> 00:44:08,239
Speaker 1: communicating between them, there are still probabilities you still have

931
00:44:08,280 --> 00:44:12,000
Speaker 1: wave functions about where these particles are, and uncertainties on

932
00:44:12,040 --> 00:44:14,200
Speaker 1: where the particles are and how much energy they have.

933
00:44:14,719 --> 00:44:17,200
Speaker 1: So in the end, the answer is very much the same, right.

934
00:44:17,360 --> 00:44:19,400
Speaker 1: A photon, even if you think about it as a particle,

935
00:44:19,680 --> 00:44:23,040
Speaker 1: has an uncertainty in its location. A photon with infinitely

936
00:44:23,040 --> 00:44:26,120
Speaker 1: well known would still have an infinite uncertainty in its location,

937
00:44:26,880 --> 00:44:28,480
Speaker 1: And so even if you think about it in terms

938
00:44:28,480 --> 00:44:30,799
Speaker 1: of particles, you get the same answer. It's either a

939
00:44:30,840 --> 00:44:33,800
Speaker 1: packet of waves moving through the universe with a range

940
00:44:33,800 --> 00:44:37,359
Speaker 1: of frequencies, or it's a packet of possible particles moving

941
00:44:37,400 --> 00:44:39,680
Speaker 1: through the universe with a range of possible energies.

942
00:44:39,960 --> 00:44:42,080
Speaker 4: All right, thank you Mary for answering that question. Now,

943
00:44:42,719 --> 00:44:44,880
Speaker 4: I think what you're saying is that even if you

944
00:44:44,920 --> 00:44:47,680
Speaker 4: look at for the lightest particles, a particle is a

945
00:44:47,719 --> 00:44:50,960
Speaker 4: point particle, so itself, it doesn't have any length. So

946
00:44:50,960 --> 00:44:52,640
Speaker 4: it kind of doesn't make sense to talk about the

947
00:44:52,719 --> 00:44:55,799
Speaker 4: length of a photon. But these point particles have a

948
00:44:55,840 --> 00:44:58,080
Speaker 4: certain fuzziness about where they can be in the universe.

949
00:44:58,120 --> 00:45:00,840
Speaker 4: And maybe you can talk about the length that fuzzy

950
00:45:00,840 --> 00:45:05,160
Speaker 4: cloud of where it could be, but ultimately you kind

951
00:45:05,160 --> 00:45:07,960
Speaker 4: of have to make a call about where where you

952
00:45:08,080 --> 00:45:11,799
Speaker 4: draw those boundaries, Like these fuzzy clouds don't have a

953
00:45:11,800 --> 00:45:14,480
Speaker 4: hard edge to them, this kind of fuzzy out to infinity,

954
00:45:15,120 --> 00:45:17,000
Speaker 4: And so it's up to you to say, this is

955
00:45:17,400 --> 00:45:18,919
Speaker 4: what I would call the photon, this is what would

956
00:45:18,960 --> 00:45:20,360
Speaker 4: not call the photon exactly.

957
00:45:20,360 --> 00:45:23,160
Speaker 1: And the pure concept of a single photon isn't really helpful.

958
00:45:23,280 --> 00:45:25,560
Speaker 1: Number one, because they never exist in the universe. Number

959
00:45:25,560 --> 00:45:29,440
Speaker 1: two because they have infinite uncertainty in their location and

960
00:45:29,520 --> 00:45:30,799
Speaker 1: so they're sort of everywhere.

961
00:45:30,960 --> 00:45:35,120
Speaker 4: Cool. Well, I like this new podcast host, Mary. Does

962
00:45:35,160 --> 00:45:37,440
Speaker 4: Mary like white chocolate? Then, because she's.

963
00:45:37,239 --> 00:45:40,200
Speaker 1: The no, she agrees with me and everything else.

964
00:45:41,440 --> 00:45:45,960
Speaker 4: Right. All right, Well, let's talk about how you might

965
00:45:46,040 --> 00:45:48,880
Speaker 4: actually measure what you might call the length of a photon,

966
00:45:49,040 --> 00:45:52,479
Speaker 4: or not measure it, or maybe it's impossible. So let's

967
00:45:52,480 --> 00:45:55,320
Speaker 4: dig into that question. But first, let's take one more Break.

968
00:46:00,120 --> 00:46:01,920
Speaker 1: A piece of cheese into your mouth, or enjoy a

969
00:46:02,040 --> 00:46:05,440
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970
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971
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972
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973
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974
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975
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976
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977
00:46:28,680 --> 00:46:31,920
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978
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979
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980
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981
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982
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983
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984
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985
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986
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1014
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Speaker 4: All Right, we're talking about the length of a photon,

1015
00:48:24,440 --> 00:48:29,239
Speaker 4: and now is it Daniel's backwards? It's still merry.

1016
00:48:30,960 --> 00:48:32,040
Speaker 1: Let's go back to Daniel.

1017
00:48:34,080 --> 00:48:37,759
Speaker 4: All Right, we've sort of concluded that, you know, light

1018
00:48:37,880 --> 00:48:40,080
Speaker 4: is a fuzzy quantum thing, so to talk about its

1019
00:48:40,160 --> 00:48:42,799
Speaker 4: length kind of doesn't make sense. But there's sort of

1020
00:48:42,800 --> 00:48:44,960
Speaker 4: the other aspect of which is what I was trying

1021
00:48:44,960 --> 00:48:46,880
Speaker 4: to get at, which is like, when you measure a photon,

1022
00:48:47,080 --> 00:48:49,600
Speaker 4: maybe you can measure its length sort of because maybe

1023
00:48:49,600 --> 00:48:51,880
Speaker 4: it depends on how big your eyeball is or how

1024
00:48:52,640 --> 00:48:54,439
Speaker 4: you know, how long you're there waiting for the hot

1025
00:48:54,440 --> 00:48:56,359
Speaker 4: dog to hit you. So let's talk about measuring How

1026
00:48:56,400 --> 00:48:58,839
Speaker 4: do you measure a photon and how does it change

1027
00:48:58,840 --> 00:48:59,480
Speaker 4: the length of it?

1028
00:48:59,760 --> 00:49:01,759
Speaker 1: Yeah, yeah, this is really fun. I spent some time

1029
00:49:01,800 --> 00:49:04,759
Speaker 1: thinking about this and starting with how you measure the

1030
00:49:04,800 --> 00:49:07,360
Speaker 1: size of other particles. It's a little bit easier to

1031
00:49:07,400 --> 00:49:10,319
Speaker 1: think about like measuring the size of a proton, because

1032
00:49:10,360 --> 00:49:13,040
Speaker 1: we've done that, or try to measure the size of

1033
00:49:13,040 --> 00:49:14,960
Speaker 1: the electron, because we've tried to do that.

1034
00:49:15,239 --> 00:49:17,320
Speaker 4: But we have measured the length of a proton.

1035
00:49:17,440 --> 00:49:19,800
Speaker 1: We have measured the width of a proton. Yes, absolutely,

1036
00:49:19,800 --> 00:49:21,840
Speaker 1: we know something about the size of a proton.

1037
00:49:22,040 --> 00:49:24,239
Speaker 4: Wait wait, I thought we just concluded that you can't

1038
00:49:24,239 --> 00:49:25,560
Speaker 4: do that with quantum particles.

1039
00:49:25,840 --> 00:49:28,600
Speaker 1: We decided you can. But protons are not like fundamental

1040
00:49:28,640 --> 00:49:31,680
Speaker 1: objects in the universe, right, So really we're talking about

1041
00:49:31,680 --> 00:49:33,680
Speaker 1: like a bound state of quarks and how close do

1042
00:49:33,719 --> 00:49:34,759
Speaker 1: they stay to each other.

1043
00:49:34,880 --> 00:49:37,239
Speaker 4: But even that has a sort of an uncertainty that

1044
00:49:37,360 --> 00:49:39,520
Speaker 4: spills out to infinity, doesn't it. So where do you

1045
00:49:39,560 --> 00:49:42,360
Speaker 4: define the bounds of a proton?

1046
00:49:42,520 --> 00:49:44,040
Speaker 1: Yeah, it's a little bit fuzzy, and you have to

1047
00:49:44,080 --> 00:49:46,440
Speaker 1: do a little bit of mental gymnastics and come up

1048
00:49:46,480 --> 00:49:49,760
Speaker 1: with a concept of size that makes sense for these particles.

1049
00:49:49,760 --> 00:49:52,160
Speaker 1: You have to think about like what can I actually

1050
00:49:52,200 --> 00:49:54,759
Speaker 1: measure and what number does that give me? And is

1051
00:49:54,800 --> 00:49:57,240
Speaker 1: that really measuring the size of the object.

1052
00:49:57,520 --> 00:50:00,239
Speaker 4: All right, let me do some mental stretching here, do

1053
00:50:00,280 --> 00:50:03,239
Speaker 4: some mental gymnastics. Well, what do you mean? And so

1054
00:50:03,480 --> 00:50:05,880
Speaker 4: when you say the side, because you just said the

1055
00:50:05,920 --> 00:50:08,880
Speaker 4: size of a proton pretty decisively, would then as a

1056
00:50:08,880 --> 00:50:11,840
Speaker 4: particle physicist, what do you define as the edge of

1057
00:50:11,840 --> 00:50:12,320
Speaker 4: a proton?

1058
00:50:12,440 --> 00:50:15,040
Speaker 1: Yeah, so I will be totally upfront here the physics

1059
00:50:15,040 --> 00:50:18,640
Speaker 1: has redefined size and then answered the question what we

1060
00:50:18,760 --> 00:50:20,680
Speaker 1: really mean is that we do a specific kind of

1061
00:50:20,760 --> 00:50:24,719
Speaker 1: experiment where we bounce stuff off the proton and we

1062
00:50:24,920 --> 00:50:28,480
Speaker 1: notice how that changes as we scan across a proton. So,

1063
00:50:28,560 --> 00:50:31,359
Speaker 1: for example, you shoot electrons at the proton and they

1064
00:50:31,360 --> 00:50:33,279
Speaker 1: mostly go through, and then you shoot them a little

1065
00:50:33,280 --> 00:50:35,319
Speaker 1: bit to the right and oops, now they're bouncing back

1066
00:50:35,360 --> 00:50:38,320
Speaker 1: or now they're exploding the proton. And as you keep going,

1067
00:50:38,360 --> 00:50:41,040
Speaker 1: you discover that as you sweep your beam over past

1068
00:50:41,120 --> 00:50:43,439
Speaker 1: the other side of the proton, then now it's missing

1069
00:50:43,520 --> 00:50:46,400
Speaker 1: the proton again. So there's like a size of the

1070
00:50:46,400 --> 00:50:48,760
Speaker 1: proton there in the sense of like how it reacts

1071
00:50:48,800 --> 00:50:52,640
Speaker 1: to the beam and electrons that you're sweeping over it.

1072
00:50:52,640 --> 00:50:55,880
Speaker 4: It's sort of like searching for a stud on your wall, right.

1073
00:50:55,880 --> 00:50:59,040
Speaker 1: Yeah, exactly. It's a little bit philosophical to interpret this

1074
00:50:59,200 --> 00:51:01,520
Speaker 1: as size is because what do you mean anyway by

1075
00:51:01,560 --> 00:51:04,000
Speaker 1: the size of a proton? A proton is an easier

1076
00:51:04,080 --> 00:51:06,080
Speaker 1: thing to talk about than a photon, because at least

1077
00:51:06,080 --> 00:51:08,440
Speaker 1: a proton has mass. You can like hold one, you

1078
00:51:08,480 --> 00:51:10,680
Speaker 1: can capture one, you can say this is the one

1079
00:51:10,719 --> 00:51:13,200
Speaker 1: I'm talking about. Photons are much harder, and we'll talk

1080
00:51:13,200 --> 00:51:14,480
Speaker 1: in a minute about how you might be able to

1081
00:51:14,480 --> 00:51:16,359
Speaker 1: measure their size. But this is the kind of thing

1082
00:51:16,400 --> 00:51:18,319
Speaker 1: we do for a proton, and this is one way,

1083
00:51:18,360 --> 00:51:21,040
Speaker 1: for example, that we discovered that the atom had a

1084
00:51:21,040 --> 00:51:24,920
Speaker 1: proton inside of it. Right. Rutherford's original experiment was basically this.

1085
00:51:25,160 --> 00:51:27,400
Speaker 1: You shut alpha particles at gold foils and notice that

1086
00:51:27,400 --> 00:51:29,640
Speaker 1: they bounce back sometimes and not other times. And he

1087
00:51:29,719 --> 00:51:32,200
Speaker 1: used this to see like, oh, there's like hard little

1088
00:51:32,280 --> 00:51:35,360
Speaker 1: nuggets inside the gold foil, and those were the nuclei.

1089
00:51:35,680 --> 00:51:37,360
Speaker 1: And you can do the same kind of thing to

1090
00:51:37,360 --> 00:51:39,120
Speaker 1: see the size or a proton. You can also do

1091
00:51:39,160 --> 00:51:41,320
Speaker 1: the same kind of thing to see inside a proton

1092
00:51:41,400 --> 00:51:43,480
Speaker 1: to see like how often is it bouncing off of

1093
00:51:43,480 --> 00:51:45,360
Speaker 1: a quark that's inside the proton?

1094
00:51:45,719 --> 00:51:45,839
Speaker 2: Right?

1095
00:51:45,920 --> 00:51:47,840
Speaker 4: But like you said, it's sort of a fuzzy boundary,

1096
00:51:47,840 --> 00:51:50,440
Speaker 4: isn't it. Like as you're scanning where the proton is

1097
00:51:50,440 --> 00:51:53,320
Speaker 4: by shooting electrons at it, at some point like sometimes

1098
00:51:53,360 --> 00:51:55,279
Speaker 4: will hit, sometimes it won't, even though you're shooting in

1099
00:51:55,320 --> 00:51:58,399
Speaker 4: the same exact direction. And as you scan through the right,

1100
00:51:58,480 --> 00:52:01,520
Speaker 4: for example, the frequency of which it might glance off

1101
00:52:01,560 --> 00:52:04,800
Speaker 4: of the proton changes. So there's a bit of fuzziness.

1102
00:52:04,800 --> 00:52:06,279
Speaker 4: So when do you make the call like, okay, that's

1103
00:52:06,320 --> 00:52:08,480
Speaker 4: the edge of the proton or do you know.

1104
00:52:08,520 --> 00:52:10,480
Speaker 1: You're exactly right? There's a little bit of fuzziness there.

1105
00:52:10,480 --> 00:52:13,200
Speaker 1: Like if you did this experiment with billiard balls, right,

1106
00:52:13,280 --> 00:52:15,200
Speaker 1: there'd be a moment when they come into contact and

1107
00:52:15,239 --> 00:52:17,839
Speaker 1: then a moment when they don't, and there's a precision there,

1108
00:52:18,160 --> 00:52:20,840
Speaker 1: and we don't have the same thing with protons. There's

1109
00:52:20,960 --> 00:52:23,280
Speaker 1: some point at which you shoot the electron and sometimes

1110
00:52:23,280 --> 00:52:25,960
Speaker 1: it bounces back and sometimes it passes through, and so

1111
00:52:26,040 --> 00:52:28,520
Speaker 1: like is that the edge of the proton? And so

1112
00:52:28,560 --> 00:52:30,840
Speaker 1: we just make a sort of mathematical definition. We define

1113
00:52:30,840 --> 00:52:33,239
Speaker 1: the width of this distribution, and we say that with

1114
00:52:33,360 --> 00:52:36,600
Speaker 1: of this distribution tells us the size of the proton.

1115
00:52:36,360 --> 00:52:39,200
Speaker 4: Meaning like the width of a proton is the width

1116
00:52:39,239 --> 00:52:42,680
Speaker 4: at which if you aim at electron added beyond that,

1117
00:52:42,960 --> 00:52:45,759
Speaker 4: then only you know ten percent of them will hit.

1118
00:52:45,680 --> 00:52:47,960
Speaker 1: It, exactly like if you know a Gaussian distribution, you

1119
00:52:47,960 --> 00:52:50,560
Speaker 1: can characterize the width of it. It doesn't capture the

1120
00:52:50,600 --> 00:52:53,040
Speaker 1: whole distribution. It's just like a characteristic number that tells

1121
00:52:53,080 --> 00:52:56,239
Speaker 1: you roughly how wide it is. And there's a possibility

1122
00:52:56,239 --> 00:52:58,160
Speaker 1: you go pass that with and you still interact with

1123
00:52:58,200 --> 00:53:00,400
Speaker 1: the proton. And there's a possibility you go low that

1124
00:53:00,400 --> 00:53:02,520
Speaker 1: with and you don't interact with the proton. So it's

1125
00:53:02,560 --> 00:53:06,040
Speaker 1: a quantum fuzzy definition of size. That's fuzzy in another

1126
00:53:06,080 --> 00:53:08,560
Speaker 1: way too, because it depends on the thing you're touching

1127
00:53:08,640 --> 00:53:12,440
Speaker 1: it with. Like protons will react to electrons differently than

1128
00:53:12,480 --> 00:53:15,880
Speaker 1: they'll react to muons or react to neutrinos. So the

1129
00:53:15,880 --> 00:53:19,279
Speaker 1: whole concept of size is really about the interaction of

1130
00:53:19,440 --> 00:53:22,960
Speaker 1: two things. It's not inherent property of the object anyway,

1131
00:53:23,400 --> 00:53:26,080
Speaker 1: at least this quantum definition of size.

1132
00:53:25,800 --> 00:53:27,640
Speaker 4: I see, like it depends on the experiment. The width

1133
00:53:27,640 --> 00:53:29,520
Speaker 4: of a proton you can't talk about the width of

1134
00:53:29,520 --> 00:53:31,520
Speaker 4: a proton. You have to say, what's the width of

1135
00:53:31,560 --> 00:53:34,120
Speaker 4: a proton when it's interacting with electrons, or what's the

1136
00:53:34,120 --> 00:53:37,400
Speaker 4: width of a proton when it's interacting with hot dog ginos.

1137
00:53:37,960 --> 00:53:39,200
Speaker 4: Even then it's fuzzy and you kind of have to

1138
00:53:39,239 --> 00:53:41,720
Speaker 4: make a call and say, well, you know it's about

1139
00:53:41,760 --> 00:53:45,120
Speaker 4: here that it starts to taper off. Yeah, exactly, all right,

1140
00:53:45,160 --> 00:53:47,799
Speaker 4: So then let not switch to photons. Does the same

1141
00:53:47,840 --> 00:53:49,799
Speaker 4: thing apply to photons? Like does it depend on how

1142
00:53:49,840 --> 00:53:50,400
Speaker 4: we measure it?

1143
00:53:50,440 --> 00:53:52,800
Speaker 1: So this is tricky because photons don't like to interact

1144
00:53:52,800 --> 00:53:55,440
Speaker 1: with each other. You can't just like shoot one photon

1145
00:53:55,480 --> 00:53:57,360
Speaker 1: in another and say, like how often are they going

1146
00:53:57,400 --> 00:53:59,960
Speaker 1: to touch each other? This kind of stuff. Remember, photons

1147
00:54:00,080 --> 00:54:02,799
Speaker 1: only interact with things that have electric charge, So you

1148
00:54:02,800 --> 00:54:06,200
Speaker 1: can shoot photons at electrons, but you can't shoot photons

1149
00:54:06,200 --> 00:54:09,239
Speaker 1: at photons and see them interact very often. When they do,

1150
00:54:09,280 --> 00:54:13,319
Speaker 1: it's because they've actually spontaneously transformed into electrons and positrons

1151
00:54:13,360 --> 00:54:15,239
Speaker 1: and then interacted. So I was thinking about it, and

1152
00:54:15,280 --> 00:54:17,000
Speaker 1: there's another way you might be able to get a

1153
00:54:17,080 --> 00:54:20,040
Speaker 1: sense for the length of a photon. Because photons don't

1154
00:54:20,040 --> 00:54:22,480
Speaker 1: interact with each other the same way particles do, but

1155
00:54:22,520 --> 00:54:25,600
Speaker 1: they can interfere with each other. If photons are at

1156
00:54:25,600 --> 00:54:28,640
Speaker 1: the same place at the same time, they will interfere,

1157
00:54:28,680 --> 00:54:31,239
Speaker 1: like the way we have interferometers. You know, we talk

1158
00:54:31,280 --> 00:54:33,920
Speaker 1: about interference, you get like light patches and dark patches.

1159
00:54:34,000 --> 00:54:36,160
Speaker 4: Wait, wait, let maybe take a step back. What is

1160
00:54:36,200 --> 00:54:38,040
Speaker 4: it that you're trying to do. You're trying to measure

1161
00:54:38,480 --> 00:54:41,000
Speaker 4: the size of this wave packet or the size of

1162
00:54:41,040 --> 00:54:43,360
Speaker 4: the fuzziness of an electron. Is that kind of what

1163
00:54:43,400 --> 00:54:43,920
Speaker 4: you're trying to do.

1164
00:54:44,000 --> 00:54:46,000
Speaker 1: I'm thinking about how to measure the length of that

1165
00:54:46,040 --> 00:54:48,439
Speaker 1: wave packet of a photon. And I was thinking about

1166
00:54:48,480 --> 00:54:52,000
Speaker 1: if you sent two photons through an interference experiment, like

1167
00:54:52,160 --> 00:54:54,359
Speaker 1: do the interfere with each other? They will if they're

1168
00:54:54,400 --> 00:54:56,560
Speaker 1: right on top of each other, they won't. If they're

1169
00:54:56,600 --> 00:54:59,920
Speaker 1: really separated, like if you wait ten seconds between shooting photons,

1170
00:55:00,080 --> 00:55:02,440
Speaker 1: they won't interfere with each other. There's some point in

1171
00:55:02,480 --> 00:55:05,160
Speaker 1: which if you send two photons through the experiment close

1172
00:55:05,280 --> 00:55:08,640
Speaker 1: enough together in time that their wave packets are overlapping,

1173
00:55:08,840 --> 00:55:11,040
Speaker 1: that they will interfere with each other. And so I'm

1174
00:55:11,040 --> 00:55:14,040
Speaker 1: thinking that's like one way to define the width of

1175
00:55:14,120 --> 00:55:17,240
Speaker 1: the wave packet of each photon is like how close

1176
00:55:17,280 --> 00:55:19,600
Speaker 1: they have to be to each other in time, which

1177
00:55:19,640 --> 00:55:22,560
Speaker 1: then gets translated to distance so that they start interfering

1178
00:55:22,600 --> 00:55:23,120
Speaker 1: with each other.

1179
00:55:23,320 --> 00:55:26,080
Speaker 4: Doesn't light interact with electrons? For example? So like we

1180
00:55:26,200 --> 00:55:28,879
Speaker 4: use electrons like you just said, to measure the width

1181
00:55:28,920 --> 00:55:30,960
Speaker 4: of a proton, couldn't we kind of flip it and

1182
00:55:31,040 --> 00:55:34,040
Speaker 4: use an electron to measure the width of a light particle?

1183
00:55:34,239 --> 00:55:36,080
Speaker 4: Like what if I sit an electron there on a

1184
00:55:36,160 --> 00:55:39,400
Speaker 4: table and I just shoot photons at it? Wouldn't this

1185
00:55:39,520 --> 00:55:42,120
Speaker 4: sort of tell me how wine my photon is?

1186
00:55:42,360 --> 00:55:43,840
Speaker 1: Yeah? But are we talking about the length of a

1187
00:55:43,840 --> 00:55:45,560
Speaker 1: photon or the width of a photon?

1188
00:55:45,680 --> 00:55:45,839
Speaker 4: Wait?

1189
00:55:45,880 --> 00:55:46,040
Speaker 1: Wait?

1190
00:55:46,160 --> 00:55:48,359
Speaker 4: Meaning like is it light shape like a hot dog?

1191
00:55:49,719 --> 00:55:52,240
Speaker 4: Let's assume the light is shape like a meatball. Wouldn't

1192
00:55:52,280 --> 00:55:53,920
Speaker 4: the length also tell you the width?

1193
00:55:54,040 --> 00:55:56,520
Speaker 1: The length or the width it depends on the uncertainty

1194
00:55:56,520 --> 00:55:58,760
Speaker 1: of its production? Right? The entire length of the photon

1195
00:55:58,840 --> 00:56:01,640
Speaker 1: comes from the uncertainty you have in how it was produced.

1196
00:56:01,680 --> 00:56:04,960
Speaker 1: It's either infinitely long if it's perfectly well measured, or

1197
00:56:05,000 --> 00:56:07,560
Speaker 1: it's very very tied if it's very uncertain in its energy.

1198
00:56:07,920 --> 00:56:10,879
Speaker 1: So the width might come from a different uncertainty. So yeah,

1199
00:56:10,960 --> 00:56:12,560
Speaker 1: if you want to talk about the width of the photon,

1200
00:56:12,640 --> 00:56:15,040
Speaker 1: like which direction does it come out of the laser,

1201
00:56:15,120 --> 00:56:18,600
Speaker 1: this uncertainty there in the photon's width as well as

1202
00:56:18,640 --> 00:56:20,600
Speaker 1: in its length. That could be a different.

1203
00:56:20,400 --> 00:56:22,040
Speaker 4: Number, But I feel like when you were talking about

1204
00:56:22,080 --> 00:56:24,960
Speaker 4: the proton, you were using the word length to mean

1205
00:56:25,000 --> 00:56:25,239
Speaker 4: it's with.

1206
00:56:25,640 --> 00:56:28,920
Speaker 1: Yeah, for proton, we really are measuring it's with in

1207
00:56:28,920 --> 00:56:29,440
Speaker 1: that case.

1208
00:56:29,480 --> 00:56:35,040
Speaker 4: You're right, so you're assuming protons are meat bull shaped? Well,

1209
00:56:35,440 --> 00:56:37,359
Speaker 4: I mean I think is important, right, No, No, you're right.

1210
00:56:37,440 --> 00:56:38,000
Speaker 1: Yeah, you're right.

1211
00:56:38,440 --> 00:56:40,600
Speaker 4: So you're assuming protons are meat bull shapes. But do

1212
00:56:40,680 --> 00:56:42,880
Speaker 4: you're not assuming that light is meat bull shape? You're

1213
00:56:42,880 --> 00:56:44,840
Speaker 4: assuming it might be hot dog shape or not. I

1214
00:56:44,880 --> 00:56:45,160
Speaker 4: don't know.

1215
00:56:45,280 --> 00:56:47,760
Speaker 1: Yeah, absolutely, I'm using the meatbond model of a proton,

1216
00:56:47,880 --> 00:56:50,799
Speaker 1: the hot dog model of a photon, and somebody else

1217
00:56:50,840 --> 00:56:53,920
Speaker 1: might have a different, you know, maybe a French version

1218
00:56:53,960 --> 00:56:55,680
Speaker 1: of it. Right with there's a pastry version.

1219
00:56:56,440 --> 00:56:59,280
Speaker 4: A French fry version, the pompfleet model.

1220
00:56:59,600 --> 00:57:02,719
Speaker 1: Yes, to measure the width of a photon, you could

1221
00:57:02,760 --> 00:57:04,839
Speaker 1: scan a beam across a bunch of electrons and see

1222
00:57:04,840 --> 00:57:06,279
Speaker 1: when they interact and then will give you a sense

1223
00:57:06,280 --> 00:57:08,040
Speaker 1: for like the width of your beam, and if you

1224
00:57:08,040 --> 00:57:10,200
Speaker 1: slow it down to individual photons, if you go a

1225
00:57:10,239 --> 00:57:12,400
Speaker 1: sense of the width of the wave packet of the photon.

1226
00:57:12,600 --> 00:57:14,400
Speaker 1: I think to get a sense of the length of

1227
00:57:14,440 --> 00:57:16,560
Speaker 1: a photon, you might want to see how the photons

1228
00:57:16,800 --> 00:57:19,920
Speaker 1: overlap in an interference experiment, see when they start interfering.

1229
00:57:20,080 --> 00:57:23,080
Speaker 1: That probs something we call coherence length of the photon.

1230
00:57:23,640 --> 00:57:25,200
Speaker 4: I wonder if you can measure the length of a

1231
00:57:25,240 --> 00:57:29,440
Speaker 4: hot dog photon by measuring by using time, Like, if

1232
00:57:29,560 --> 00:57:32,640
Speaker 4: there's more uncertainty in when you receive the photon, would

1233
00:57:32,640 --> 00:57:34,760
Speaker 4: that tell you that it's a really long it's a

1234
00:57:34,760 --> 00:57:38,480
Speaker 4: foot long hot dog. I suppose if the uncertainty and

1235
00:57:38,560 --> 00:57:41,280
Speaker 4: when you receive the photon is very short, it's like, oh,

1236
00:57:41,280 --> 00:57:42,160
Speaker 4: it's a vienna hot dog.

1237
00:57:42,200 --> 00:57:44,160
Speaker 1: Yeah. And principle, if you know the energy and the uncertainty,

1238
00:57:44,360 --> 00:57:46,280
Speaker 1: you can just define the length. I was trying to

1239
00:57:46,280 --> 00:57:48,959
Speaker 1: think about a way to like experimentally measure another sense

1240
00:57:48,960 --> 00:57:51,120
Speaker 1: of the length in terms of like when two photons

1241
00:57:51,160 --> 00:57:53,760
Speaker 1: overlap with each other, rather than just thinking about the

1242
00:57:53,840 --> 00:57:57,080
Speaker 1: length of an individual photon theoretically. But yeah, you can

1243
00:57:57,120 --> 00:58:00,360
Speaker 1: definitely define the length of an individual photon theoretically from

1244
00:58:00,400 --> 00:58:02,880
Speaker 1: its energy and the uncertainty, which again is coupled to

1245
00:58:02,920 --> 00:58:04,560
Speaker 1: the uncertainty and its time measurement.

1246
00:58:04,840 --> 00:58:07,040
Speaker 4: So I feel like maybe the headline from this podcast

1247
00:58:07,040 --> 00:58:11,400
Speaker 4: episode is a physicist claim light is shaped like a hotel.

1248
00:58:14,520 --> 00:58:16,080
Speaker 1: You know, one thing I love about this podcast is

1249
00:58:16,120 --> 00:58:18,200
Speaker 1: I've never have any idea where it's going to end

1250
00:58:18,240 --> 00:58:20,400
Speaker 1: up going. There's no way to prepare for this.

1251
00:58:20,880 --> 00:58:22,520
Speaker 4: It's an uncertainty about its length.

1252
00:58:22,560 --> 00:58:26,520
Speaker 1: Also, the topic, the concept, the analogies we end up using.

1253
00:58:26,680 --> 00:58:29,680
Speaker 1: This is proof that this podcast is unscripted because nobody

1254
00:58:29,680 --> 00:58:30,520
Speaker 1: could write this stuff.

1255
00:58:33,360 --> 00:58:36,240
Speaker 4: Well we are. We're writing it right now, Daniel. It's happening.

1256
00:58:36,240 --> 00:58:36,760
Speaker 4: It's happening.

1257
00:58:36,800 --> 00:58:37,360
Speaker 1: We're living it.

1258
00:58:37,440 --> 00:58:41,120
Speaker 4: Man, Well, I mean, would you. I feel that that's

1259
00:58:41,160 --> 00:58:42,880
Speaker 4: the biggest thing that I'm getting out of this is

1260
00:58:42,920 --> 00:58:45,640
Speaker 4: that you know you're in your thought point of view.

1261
00:58:45,760 --> 00:58:49,480
Speaker 4: A photon is not spherical, It's maybe has different dimensions

1262
00:58:49,480 --> 00:58:49,720
Speaker 4: to it.

1263
00:58:49,840 --> 00:58:51,800
Speaker 1: Yeah, I hadn't thought about the width of a photon,

1264
00:58:51,880 --> 00:58:55,000
Speaker 1: but you're right, it has all the same theoretical questions

1265
00:58:55,040 --> 00:58:58,120
Speaker 1: to it and experimental trickery to measure the width of it.

1266
00:58:58,160 --> 00:58:59,880
Speaker 1: But the width and the length of a photon could

1267
00:58:59,880 --> 00:59:02,120
Speaker 1: be very different. You could have a source of photons

1268
00:59:02,120 --> 00:59:05,120
Speaker 1: that's very uncertain in length and very certain in width.

1269
00:59:05,280 --> 00:59:07,920
Speaker 4: I think that you know, as you you gave a

1270
00:59:07,920 --> 00:59:11,160
Speaker 4: proton of definite size, right like in physics you have

1271
00:59:11,200 --> 00:59:13,400
Speaker 4: a size with plus or mind is a certain amount

1272
00:59:13,440 --> 00:59:15,840
Speaker 4: of uncertainty. If you had to do that for a light,

1273
00:59:16,000 --> 00:59:18,440
Speaker 4: for a photon, like maybe an everyday photon that we

1274
00:59:18,520 --> 00:59:21,160
Speaker 4: see every day, what would you say it is its length?

1275
00:59:21,600 --> 00:59:24,080
Speaker 1: Yeah, that's a great question. You know, a typical photon

1276
00:59:24,200 --> 00:59:27,480
Speaker 1: that's like coming out of the light that's made from

1277
00:59:27,520 --> 00:59:29,360
Speaker 1: a light bulb in your house, and that's a glow

1278
00:59:29,400 --> 00:59:31,440
Speaker 1: of like a little piece of metal. So there's a

1279
00:59:31,520 --> 00:59:34,680
Speaker 1: very wide spread in the uncertainty of those photons.

1280
00:59:34,760 --> 00:59:37,680
Speaker 4: Oh cool, Now, how would you say it compares to

1281
00:59:37,760 --> 00:59:38,320
Speaker 4: its width?

1282
00:59:38,880 --> 00:59:39,000
Speaker 9: Like?

1283
00:59:39,160 --> 00:59:42,600
Speaker 4: Are photons hot like the everyday photons we see hot?

1284
00:59:42,680 --> 00:59:44,920
Speaker 4: Duck shaped or are they football shaped? Or are they

1285
00:59:45,040 --> 00:59:46,120
Speaker 4: more spherically taped?

1286
00:59:47,080 --> 00:59:47,160
Speaker 7: Like?

1287
00:59:47,200 --> 00:59:48,960
Speaker 4: What kind of bunch? What kind of bunch should I

1288
00:59:48,960 --> 00:59:49,600
Speaker 4: get to eat it?

1289
00:59:51,640 --> 00:59:55,160
Speaker 1: I think it's probably curved, so you should get a croissant. No,

1290
00:59:56,160 --> 00:59:57,720
Speaker 1: I don't know the answer that It depends a lot

1291
00:59:57,760 --> 01:00:00,520
Speaker 1: on the source. For a typical filament from like an

1292
01:00:00,560 --> 01:00:02,920
Speaker 1: incandescent bulb. There's again going to be a lot of

1293
01:00:02,960 --> 01:00:05,400
Speaker 1: uncertainty in the direction, so these things are going to

1294
01:00:05,480 --> 01:00:08,280
Speaker 1: be pretty fat. Maybe there's sausage paddies after all.

1295
01:00:08,560 --> 01:00:10,680
Speaker 4: Oh yeah, oh man, I hadn't even thought about that

1296
01:00:10,720 --> 01:00:14,000
Speaker 4: snack like they could be like pancakes flying at youa

1297
01:00:14,200 --> 01:00:15,160
Speaker 4: face forward.

1298
01:00:15,080 --> 01:00:16,360
Speaker 1: Yeah, more sideways.

1299
01:00:16,520 --> 01:00:19,160
Speaker 4: Yeah. Interesting. All right, So I guess we sort of

1300
01:00:19,160 --> 01:00:21,160
Speaker 4: answered the question how long a photon is?

1301
01:00:21,400 --> 01:00:23,600
Speaker 1: We know that these things are really hard to think about,

1302
01:00:23,680 --> 01:00:25,320
Speaker 1: and that the answer depends a little bit on the

1303
01:00:25,400 --> 01:00:27,960
Speaker 1: question you're asking and exactly how you want to answered,

1304
01:00:28,120 --> 01:00:31,160
Speaker 1: and along the way you often have to redefine what

1305
01:00:31,240 --> 01:00:33,800
Speaker 1: you mean by your question in order to get a specific,

1306
01:00:34,000 --> 01:00:35,040
Speaker 1: unsatisfying answer.

1307
01:00:35,520 --> 01:00:37,040
Speaker 4: Yeah, and in the end, I guess it's all a

1308
01:00:37,080 --> 01:00:40,640
Speaker 4: little bit fuzzy due to the fuzzy nature of the universe.

1309
01:00:40,920 --> 01:00:43,120
Speaker 1: But put enough mustard on it, it'll be delicious.

1310
01:00:43,480 --> 01:00:49,520
Speaker 4: Yeah, it's a little fuzzy though. The Fuzzy Hot Dog podcast.

1311
01:00:50,240 --> 01:00:54,200
Speaker 4: All right, Well, another interesting dive into the quantum nature

1312
01:00:54,200 --> 01:00:57,120
Speaker 4: of the universe and how even simple questions like how

1313
01:00:57,120 --> 01:00:59,920
Speaker 4: big is a photon or what shape it has requires

1314
01:00:59,920 --> 01:01:04,840
Speaker 4: a whole conversation about the nature of length and what

1315
01:01:04,960 --> 01:01:06,760
Speaker 4: even means to be something in the universe.

1316
01:01:06,920 --> 01:01:10,040
Speaker 1: That's right. The most basic questions are the hardest to answer.

1317
01:01:10,400 --> 01:01:12,360
Speaker 4: All right, well, we hope you enjoyed that. Thanks for

1318
01:01:12,440 --> 01:01:13,880
Speaker 4: joining us. See you next time.

1319
01:01:18,640 --> 01:01:21,520
Speaker 1: For more science and curiosity, come find us on social

1320
01:01:21,560 --> 01:01:26,480
Speaker 1: media where we answer questions and post videos. We're on Twitter, Discord, Instant,

1321
01:01:26,560 --> 01:01:30,280
Speaker 1: and now TikTok. Thanks for listening and remember that Daniel

1322
01:01:30,320 --> 01:01:33,720
Speaker 1: and Jorge Explain the Universe is a production of iHeartRadio.

1323
01:01:34,040 --> 01:01:37,920
Speaker 1: For more podcasts from iHeart Radio, visit the iHeartRadio app,

1324
01:01:38,200 --> 01:01:41,680
Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.

1325
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Speaker 1: When you pop a piece of cheese into your mouth,

1326
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Speaker 1: you're probably not thinking about the environmental impact. But the

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Speaker 1: people in the dairy industry are. That's why they're working

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Speaker 1: hard every day to find new ways to reduce waste,

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Speaker 1: conserve natural resources, and drive down greenhouse gas. How is

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Speaker 1: us dairy tackling greenhouse gases? Many farms use anaerobic digesters

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Speaker 1: can power farms, towns, and electric cars. Visit you as

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Speaker 10: and an IQ north of one sixty, So helping the

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Speaker 12: ABC Tuesday, the series premiere of falls most anticipated new

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Speaker 12: drama High Potential. That big brain of hers is going

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Speaker 4: not pretending. I'm just out here super copping.

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Speaker 12: High Potential series premiere Tuesday, ten ninth Central on ABC

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Speaker 12: and stream on Hulu.