From the photon’s PoV, has it actually gone anywhere? Or has anything else happened at all?
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As I understand it, it was created in one place and destroyed in another in the same instant. Because it was travelling AT the speed of light, no time passed.
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What if, at some point, it travels through a medium with speed of light less than c? Would it then experience time?
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Good question. Scientists have slowed light to one mile per hour in a Bose Einstein Condensate.
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No. Because refraction and diffraction are scattering processes. It happens because light is being absorbed by electrons and re-emitted again.
So for as long as the light is moving through the medium, going between electrons it’s still going at c, but from one end of the medium to the other it’s going <c. The photon is still experiencing no time in its own reference frame.
In other words, the photon only gets to live in the medium for a few nanometers at a time as it travels from the emission out of one electron to its next collision with another. Then it “stops existing” and is just part of the electron’s energy-mass for awhile until the electron drops an energy level and re-emits a photon. The photon experiences no time, travels at the speed of light another few nanometers, then hits another electron. Rinse and repeat.
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Whoa!
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Or did the photon stand still and the rest of the universe moved around it (in an instant)?
I read ‘Relativity’ about 23 years ago, when my brain was at its peak powers, and I didn’t quite wrap my head around it then…
Damn. I’m actually pretty wrong.
Here’s some real physicists explaining how, in diffraction, the light itself is somehow really going slower than c.
Much harder to wrap your head around than plain old scattering. But scattering is pretty obviously wrong for the reasons pointed out (if it were all just scattering, it’d either be stochastic and the diffractive indices for materials wouldn’t be so perfectly repeatable, or there’d only be transparency for very specific wavelengths)
Specifically, with the QM polariton solution, you’re treating light in the medium as a field excitation that isn’t the exact same as a photon. And polaritons have mass, so they move slower than c, and I would expect actually do experience time in its own reference frame like anything else moving slower than c.
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I was hoping that Einstein would be riding shotgun, but I realized that he was way ahead of me and I never could catch up.
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Well, if you count the photon’s journey as all the same instant, you should also count it all as the same place. Time dilation goes with length contraction; as the time involved goes to zero, so does the distance involved. A photon then doesn’t really perceive any space or time.
A maybe better way to put it is that measuring time and space doesn’t really apply to them. An observer defines their time by their path into the future, and their space as perpendicular to that. But a photon doesn’t really have a path into the future to begin with, just along its border with the spacetime elsewhere. So you can still talk about the 4-D spacetime it passes through, but not break it down in the usual way.
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a ways out past Jupiter
He’s credited at the end, along with the performers. (Don’t you hate it when you have to sit through 804000000 km to find out what a piece of music is?)
Interestingly, a couple years ago, I had a boss that was Ex-MSFT who oversaw a project me and some other devs were puzzling out.
I was, as much as anyone could be that didn’t work on the framework at MSFT, the expert (Boss unrelated to said framework). Every breakthrough, “Shake and bake! THAT JUST HAPPENED!”
Hey man. Maybe a little early. Often, complications came up in QA, which yielded the next layer of the onion.
Actually appropriate, looking back and having finally seen the movie.
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Yeah, but when it comes to physics and science, I find it valuable to correct my mistakes as best I can. I may look like an insensitive asshole here, but the thing is, I do care about what people think about me to an extent. And I absolutely don’t want people to get the impression that I’m unwilling to admit I’m wrong when it comes to science.
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My apologies for appearing to throw shade on you; I just thought my anecdote would have more context if I replied to you instead of @hello_friends.
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Shade? Naaaw. I was just explaining why I compulsively have to correct myself when I explain something wrongly.[quote=“LDoBe, post:35, topic:78341”]
I may look like an insensitive asshole here
[/quote]
^^^ This is meant generally on the BBS. Not here specifically.
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