Sean Carroll
speaker
26,727 appearances
49 recordings
4 series
first heard Apr 2024
last heard 6d ago
Sean Carroll’s voice in public audio — every appearance, attributed to the second.
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recordings per month · last 12 monthsRecordings per month over the last 12 months — 29 in all, peaking in Jun 2026 with 6.
Appearances
There never was an interference pattern in that case.
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And the reason why is because the particle is sort of already entangled with the rest of the world by the setup, right?
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When you do the original version of the double slit experiment and the particle just goes through two slits and you quote unquote detect which it goes through.
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What that means is that you've entangled that particle with the rest of the world, in this case your detector for the location of the electron.
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As long as that
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Entanglement is there.
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The electron is no longer in a pure state all by itself.
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It's connected to the rest of the world, and that's what destroys the interference pattern on the other side.
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Here, I was so focused on what happens if you start measuring what happens when the particle goes through the slit that I didn't stop to think, well, what if you don't measure?
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What if you just let it go through?
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Here that particle's already entangled with the rest of the world by the setup of the question, and therefore what it emerges on the other side of the slits is not in a pure state that can interfere.
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Okay?
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So you already
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don't get an interference pattern.
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You've basically pre-detected, ev pre measured, even if you don't know the outcome of the measurement, by putting the electron or the particle moving into an entangled state, you have implicitly
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measured which one which slit it goes through and therefore you've destroyed the interference pattern.
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And that's good news.
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This was pointed out to me by an email from a physicist friend, Guy Franzman, but also the AMA questionners this month, Ashley and Jeffrey.
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So it's good news because if you could do this, if you could actually have an interference pattern and turn it on and off just by detecting particles at one of the detectors.
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And therefore have the interference pattern go on and off, appear and disappear on the other one, you could send signals faster than the speed of light.
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