Light doesn’t travel the same speed in water or glass as in a vacuum.
In a medium, light usually does not propagate at a speed equal to c; further, different types of light wave will travel at different speeds. The speed at which the individual crests and troughs of a plane wave (a wave filling the whole space, with only one frequency) propagate is called the phase velocity vp. A physical signal with a finite extent (a pulse of light) travels at a different speed. The overall envelope of the pulse travels at the group velocity vg, and its earliest part travels at the front velocity vf.
That’s light as an aggregate wave. Photons, actual light, always travel at c. What’s happening in a medium is the rapid absorption and readmission of photons. The probability of admission is based on structure of material causing things like lens or mirrors to work.
You can think of it as the photons having to jump between platforms before the can continue running at c.
What’s happening in a medium is the rapid absorption and readmission of photons. […]
You can think of it as the photons having to jump between platforms before the can continue running at c.
That’s an intuitive model, but unfortunately it doesn’t have the advantage of actually being correct. Photons are not being absorbed and reemitted. See here for why: https://lemmy.world/comment/5444224
That is wrong. Stochastic yes. Photons emission is probabilistic. Destructive interference causes emission to overwhelming follow classical wave theory. Here’s a better explanation with a neat graphic.
It sounds like you’re conflating different concepts. A stochastic process like absorption/reemission would blur the light, so that’s not it. And the linked explanation is basically correct (in classical physics at least), but it doesn’t corroborate what you originally claimed as that’s not necessarily requiring absorbing anything. Photons can jiggle the charged particles in glass and get them to make new phase shifted light despite not being absorbed.
But doesn’t relativity explicitly state that c is the speed of light in a vacuum, and travelling through other mediums explicitly changes and is explained by relativity?
Don’t think about individual photons. Think about billions of them with destructive and constructive interference. The probabilities of all the sitting l additive waves of light.
They change direction and speed, right?
The fact that light cannot change speed is one of the core axioms of relativity
Light doesn’t travel the same speed in water or glass as in a vacuum.
https://en.wikipedia.org/wiki/Speed_of_light#In_a_medium
That’s light as an aggregate wave. Photons, actual light, always travel at c. What’s happening in a medium is the rapid absorption and readmission of photons. The probability of admission is based on structure of material causing things like lens or mirrors to work.
You can think of it as the photons having to jump between platforms before the can continue running at c.
That’s an intuitive model, but unfortunately it doesn’t have the advantage of actually being correct. Photons are not being absorbed and reemitted. See here for why: https://lemmy.world/comment/5444224
That is wrong. Stochastic yes. Photons emission is probabilistic. Destructive interference causes emission to overwhelming follow classical wave theory. Here’s a better explanation with a neat graphic.
https://physics.stackexchange.com/questions/466/what-is-the-mechanism-behind-the-slowdown-of-light-photons-in-a-transparent-medi
It sounds like you’re conflating different concepts. A stochastic process like absorption/reemission would blur the light, so that’s not it. And the linked explanation is basically correct (in classical physics at least), but it doesn’t corroborate what you originally claimed as that’s not necessarily requiring absorbing anything. Photons can jiggle the charged particles in glass and get them to make new phase shifted light despite not being absorbed.
https://youtu.be/YW8KuMtVpug
https://youtu.be/CiHN0ZWE5bk
Now I’m not sure how reflective telescopes work.
reject reflectors return to long tubes
Interference in matters structure causes classical wave like behavior.
I find so much of physics to be very intuitive and then you have light.
But doesn’t relativity explicitly state that c is the speed of light in a vacuum, and travelling through other mediums explicitly changes and is explained by relativity?
I am 100% a layman and do not know the answer.
I don’t know. I thought I used to know.
This is how I feel every time I touch any non-basal physics topic.
I swear this made sense once upon a time…
No, they don’t. They can get absorbed and re-emitted, and the space they are moving though can compress sideways. But they can’t make curves at all.
Do lenses absorb and re-emit light?
That’s basically all that refraction is. A dead giveaway is that light doesn’t move at the speed of light in them.
Yes.
Don’t think about individual photons. Think about billions of them with destructive and constructive interference. The probabilities of all the sitting l additive waves of light.