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Yes, light can be brought to a complete halt under the right conditions. To understand how this happens you need to understand what is going on when light slows down in a medium. Light is an oscillating electromagnetic field, and when it passes though anything that contains charged particles (i.e. any matter made from electrons and protons) the electric ...

1

We use the Fermi pseudopotential. The interaction of a free neutron with a free nucleus can be summarized by the effective scattering length of the interaction. For simple probabalistic reasons (explained nicely by Golub, Richardson, and Lamoreaux) most neutron-nucleus scattering lengths are positive, and so we can think of a nucleus as "a thing that ...

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My teacher told me that speed of light is constant in the universe. Your teacher is mistaken I'm afraid. The speed of light varies with gravitational potential. You can see Einstein talking about this in 1920 in the Einstein digital papers: Also see Irwin Shapiro saying the same in his Shapiro Delay paper dating from 1961: There's also ...

2

The equations that describe how light, and all other electromagnetic radiation, works have a couple of constants which mean that the speed of light is constant. The equations don't depend on where you are, what temperature it is, which way you are looking etc so we assume they apply everywhere. It is entirely possible (although experimentally unlikely) that ...

0

umm, as long as Light/Plasma is defused by Plastic/Glass in any way/form; our eyesight will not recognize/perceive an illumination of anything. TV Shows have presented the false impression of refractive amplication for lighting and lasers being selfish amplifiers. What SciFi Programs HAVE gotten-right is that an underground tunnel/cavern can be illuminated ...

1

A key to understanding this is realizing that it's not always true. In fact, at x-ray frequencies, refractive indices are typically less than 1, so that the phase velocity is faster than the vacuum speed of light. The key difference is that x-ray frequencies are well above the natural frequencies of most of the electronic excitations that are involved in the ...

2

The ideal perfectly smooth flat surface has translational invariance symmetry. That means that there is no mechanism for the scattering of a wave in the horizontal direction, and no mechanism for the change in the component of wave vector parallel to the boundary. That is, the horizontal component of wave vector is conserved. For light incident at angles ...

2

Imagine the speed of light to be $1$ meter per second and the speed of light in the medium with a high refractive index to be $\frac{1}{2}$ meters per second. If you have a single peak of a wave in the slower medium, that peak must move forwards at speed $\frac{1}{2}$, no matter what angle it's facing. In the faster medium, that peak must move forwards at ...

1

Relativity just requires "constant speed of light in vacuum". It makes no claims about the speed of light in a medium. When you are moving relative to water, you will observe a different speed of light depending on your relative velocity. But you will still have all the other effects of relativity at work - such as time dilation.

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Here's my addition. Many of the answers above use the erroneous argument that frequency is the determining quantity, on the basis that the same object viewed in different media appears to be the same colour. This is meaningless, since the light has to travel through the vitreous humor (with refractive index 1.33) immediately prior to reaching the retina. ...

2

Building on prior answers, the facts are: Color is determined by the energy of the EM Wave that reaches your eyeball. Energy is defined as $E = hf$, where $h$ is Planck's constant and $f$ is the light's frequency. Thus, the color of an EM Wave is defined by its frequency. In other words, measuring the frequency of an EM Wave is sufficient to identifying the ...

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To augment Rennie's answer with a graphical representation let me post this diagram: Imagine, if you will, not a single beam of light but a series of wavefronts. When part of the wavefront slows due to a different density, the wavelength also compresses, thus introducing the characteristic bend.

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When you say light bends I assume you are talking about refraction i.e. the change in the angle of the light given by Snell's law. You ask: If I'm running straight, and I get slowed down, shouldn't I still be running straight? but suppose one foot get slowed down while the other one didn't. In that case you would turn in the direction of the foot that ...

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Refraction of Light is not a Thermodynamic process. If you study the QED basis of refraction, you notice that the difference happens in time. The speed of light is constant, and a photon which is refracted, doesn't actually travel any slower, it just travels a longer path, and needs thus more time. If it hit's somewhere, then it's not refracted. It's gone, ...

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How a classical electromagnetic wave emerges from innumerable photons can be seen in this blog entry. It is not simple, one needs quantum field theory to start with. One should get the interaction of a single photon with a crystal lattice , and one can get a quantum mechanical solution, which will give the probability of the photon to scatter or go through ...

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