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Welcome to ANI In The Air, Wondrous Wednesdays, where I talk about something wondrous.
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Last week, I mentioned the double slit experiment, where, with two slits, and you're sending, say, photons through them,
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and when you have just one slit open, it just looks like they just go through the slit,
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and they pile up, just as one might expect, like if you were just shooting something through a slit.
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Then there's the two slit situation, where when you have two slits open, and you get this interference pattern,
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so things are not building up, like with two slits open, you might expect kind of two kind of bell curve kind of things,
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where they're just piling up, and instead you get sort of lots of interference, different waves of light and darkness there.
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And then, the slightly more mysterious part is, if you try to put a detector in front of the slits, or behind the slits I guess,
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to say which slit, you know, the photon went through, all of a sudden the interference pattern disappears.
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So, and then you also have the really telltale sign of it, which is when you dial down the intensity of the photons,
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so that's just basically a single photon going one at a time, then you see the interference pattern
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being built up over time out of the different hits by the particles.
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So, standard physics would say, okay, so what you have is a particle that's both a, well, a thing,
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which is both a wave and a particle, and depending on what you're looking at, it'll be either a wave or a particle.
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The Devil's Slit experiment kind of shows that that's kind of a silly notion,
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because in the very same experiment, you see wave behavior coming from these particles that are hitting the screen.
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So you get both particle and wave behavior at the same time, and that suggests a particle and a wave,
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which in fact is quite possible.
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The theory is called Bohmian Mechanics, or Pilot Wave Theory,
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and the basic idea is that the particles are being guided by a wave,
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and that's why you see the interference pattern.
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Now, this is a pretty simple idea.
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You'd be like, well, why didn't physicists think about it?
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Well, some did, but, and it came at a time when, you know, the philosophy of many of these scientists were,
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well, a little bit, you know, well, they were called positivists.
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They sort of, you know, only wanted to talk about the things that were in experiments and nothing else.
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So, which is, you know, not totally unreasonable, except you rapidly get to the question of, well, what's an experiment?
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And then it all falls apart.
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But the thing that really is problematic for physicists even today about this theory is that the wave is not a wave in three-dimensional space.
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It's not, so one pattern, one idea is you've got, you know, just like a kind of an invisible ocean,
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your particles are floating along it and that's why you have waves.
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That's not what's true.
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What is true is you have this wave that is a wave in a very high-dimensional space.
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The dimension is three times n, where n is the number of particles in the universe.
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In an experiment, we can reduce it to n being the number of particles involved in the experiment, except that,
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and this is where the role of experiment comes in, the environment around it is very important for understanding this.
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And this is where the, you know, detecting which slit the particle went through, where that comes about.
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Basically, as soon as the environment knows which slit it is, then in this higher-dimensional space,
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the two waves corresponding to the wave going through the two slits, they separate in this high-dimensional space,
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and so now you no longer have interference.
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And so that's really kind of the key idea.
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Now, what's really wondrous about this, and why physicists don't like it at all,
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is that it's basically entangling the entire configuration of the universe together.
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Like, technically, you can't predict anything without knowing where all the particles are at this instant.
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That in itself is problematical, but when you couple it with relativity, now we get into some problems.
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So, I think next time I'll talk a little bit about relativity, what it says about the notion of now.
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Basically, it says there is no now. I'll just spoil that for you.
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And then, probably in the following week, I'll talk about how quantum mechanics says there is a now.
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And so we have these two really foundational pillars of physics, both of which have been verified to tremendous accuracy.
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One saying there is no now, and the other one saying there has to be a now.
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And so that's really kind of a really interesting thing that needs to still get resolved, and it's not resolved yet where that lies.
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So, I hope you enjoy this little bit of wonder, and talk to you next week.