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Welcome to ANI In The Air, under the patio porch, and around Baltimore.
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This is Wondrous Wednesday where I talk about something wondrous.
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This is my second time trying to do this because for some reason I stopped the podcast before
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early and I just kept droning on and on and wasn't recording and I was like, oh, it's
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only five minutes so far.
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And guess what?
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It's way more than five minutes, so I'm kind of sad about that, but whatever.
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You'll have a much better time this time around.
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So I want to talk about quantum field theory.
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Quantum field theory is the theory of dealing with particles with the restriction of, you
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know, the speed of light is this upper limit for velocity.
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That's kind of the core.
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When physicists start tinkering with that idea, particularly Dirac, he basically came
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up with the existence of the positron, which is sort of like an electron, which is this
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little thing that, you know, carries the electricity around.
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Positron is sort of like the positive version of it.
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We don't really see it.
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So he predicted its existence based on some stuff about the equations and then it turned
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out to be true.
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It was found in some experiments, existence of it at least.
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And essentially, you know, there are various narratives about all these things, but you've
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got creation and annihilation of particles.
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That's sort of a core feature of quantum field theory and one can kind of argue that all
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of the interactions, all of the forces, the possible exception of gravity, are all mediated
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by particles kind of interacting with each other.
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So you kind of have these force particles, they're called bosons, and they hit matter
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particles called fermions, and that's sort of how things, so it's kind of like they're
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flying out, they hit these matter things, they get absorbed, and then later on they
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get emitted.
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And that's sort of, quantum field theory is dealing with that, essentially.
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So yeah, so quantum field theory is about that.
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Now, so it has creation and annihilation of particles.
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From a blowing perspective, which, you know, I've talked about before, blowing mechanics,
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the creation and annihilation of particles is, can actually be taken literally.
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So you actually have particles in boiling mechanics and you can actually have them just
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ceasing to exist when they collide with something else and coming into being from nothing.
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It's perfectly fine.
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There's a little bit of randomness in the creation of particles, but that's fine.
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There's also versions that deal with it in terms of there's kind of this sea of particles
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and every now and then one kind of travels out and you suddenly see it.
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So you know, there are different ways of approaching this.
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One thing that quantum field theory does not do is deal with gravity.
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Gravity is a mess.
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Gravity is, in terms of general relativity, says that space and time get mutated by mass,
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by the stuff, right, kind of like, the idea is like this, you have this rubber sheet and
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you have a big ball in the middle and it goes, and it pulls the rubber sheet, stretching
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it out and things are on the rubber sheet suddenly start rolling towards this big mass
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because it's all now curved.
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That's general relativity in a certain sense.
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Very complicated to do computations, but conceptually that's the idea.
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It's very different than the idea of electromagnetism, which is electricity and magnetism and there's
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just this force that's acting and it's just out there.
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Quantum field theory deals with those forces very well.
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It doesn't deal with general relativity very well because you have to describe the background.
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Quantum field theory assumes there's a background.
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So dealing with that is really hard.
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It's various things such as string theory that attempt to do this.
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To the extent that they have predictions, they don't seem to be predictions that can
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be tested any time in the near future, but it can also be very hard to actually get predictions
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out of all these theories.
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Some of these theories have multiple higher dimensions needing to come into play.
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Now on a technical level quantum field theory has a big problem of infinities.
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Basically when they go to compute something, the values get larger and larger and larger
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until they're kind of nonsensical and so they have a process called renormalization that
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allows you to subtract out these infinities.
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And people try to justify it and to some extent it can be, but it's very sort of clunky.
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But then there are theories that you can't do that subtraction and I think general relativity
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kind of fits into that and it's just like, yeah, it's a problem.
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Now from a boiling perspective, what it looks like people are doing with quantum field theory
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is so, you know, the experiments are like you just take these particles, you're running
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through some magnetic field or something to charge them up, get them going very fast and
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then they collide into each other and then you see what comes out of it because you get
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a whole bunch of particles being created from all of this energy and collision and all that.
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So quantum field theory is really about computing those things.
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And so it's natural to kind of think of it as sort of particles just kind of moving freely
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until they get near each other and then there's something that happens.
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And so they try to model it with that and that's basically where infinities come from.
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There's another viewpoint which one of my collaborators came up with where it's like,
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as I said, creation and annihilation of particles happens in quantum field theory and if you
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take that seriously and you try to get everything to kind of balance out with that viewpoint,
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all of a sudden the infinities disappear.
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So far he's only been able to get it to work for some of the simpler models but there's
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no real reason to believe it can't work for the more complicated stuff, it's just really
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hard mathematics.
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So hopefully in the future that'll be a thing.
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So yeah, sort of quantum field theory is basically the merging of special relativity where everything's
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kind of flat with quantum mechanics and you end up with creation and annihilation of particles
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as one of the biggest features.
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You get really complicated looking crazy things to compute.
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You get really thick textbooks and so that's that.
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The standard quantum field theory approaches end up with things that are not so well-defined.
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Like I said, you have all these infinities problems and so they can work around it but
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they still don't really have a good definition of it and so that can be a problem with something
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like Boeing Mechanics where you try to treat reality as existing.
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It's a silly notion, really.
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And so that's why there's this attempt to make it fit Boeing Mechanics better.
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Well it sounds like the rain's coming down, particles flowing all over the place around
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me, so I guess I will take this to say adieu.
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So hopefully these past several weeks of kind of physics stuff has been fun and interesting
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for you.
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I hope to do more Wondrous Wednesdays as we transition online, thinking about talking
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about evolution for a while and then I don't know what else.
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There's lots of wondrous stuff out there so I guess we'll see where this all takes us.