Ever wondered how light slows down when passing through a material? Here we explore why the answer is not that straightforward.
How does light slow down? : Read more
How does light slow down? : Read more
A maze, a hall of mirrors. Measure the speed of light going in to be 300,000kps. Measure it to be coming out 300,000kps. And speed through any discrete distance inside the hall of mirrors to be the same. But take the total measured time through the measured space of the maze of the hall of mirrors and the result will be a light speed slower than the constant of the speed of light.What I'm curious about then is why does light bend or refract when passing through these materials? These 3 explanations for why it slows down don't address that phenomenon. I do have QED, by Richard Feynman and while I've made several attempts to read it, just didn't get terribly far. I'm betting he addresses it.
If you could see a single-photon wide (one-dimensional) beam of light, you wouldn't see it refract. But we always observe a beam of light that has some width, or diameter, perpendicular to the direction of travel. When such a beam hits a material surface at an angle, one side of the beam hits first, and the contact point moves across until the opposite side of the beam hits last. The part of the beam that hits first is being slowed down while the other side is at full speed until it hits the surface. This bends the beam, so that it's traveling inside the material at a different angle to the surface than it was before contact. This is hard to describe in words, but easy to see in a graphic. Do a search on "refraction," then look at Images and look for one labeled "NSTA."What I'm curious about then is why does light bend or refract when passing through these materials? These 3 explanations for why it slows down don't address that phenomenon. I do have QED, by Richard Feynman and while I've made several attempts to read it, just didn't get terribly far. I'm betting he addresses it.
So a single photon will change direction upon entering a material that slows it down? Why would it do that? My answer explains the change in direction of a wavefront, but wouldn't apply to a single photon.Single photons reflect, refract and interfere just a collections of photons do. Single photons fired one at a time at a lens will act just the same. In fact, even solid particles will show a diffraction pattern through a slit when fired one at a time.