Does the speed of light vary in any other or some other condition?

Question

Does the speed of light vary in any other or some other condition?

Answer 1

Yes, the speed of light varies depending on what the light is travelling through.

In a vacuum, such as space, light travels at 299 792 458 m/s, and that is a constant - represented by the symbol c. That doesn't change, and it's the fastest light travels, and theoritically the fastest anything can travel.

The speed of light will, however, change depending on different matter that the light travels through. Probably not by much, though. For example, light travels faster in air than it does in water - and this is why we get refraction.

These changes in the speed of light are too insignificant for us to percieve. It's not as if things done underwater appear in slow-motion, or things done in space appear sped-up, while things done in air remain "normal speed". We only see it as the above-mentioned refraction in the case of air-to-water.

Answer 2

There are 2 answers to this question.

A)  Light can be slowed down when passing through a medium, like a flashlight shined into a swimming pool.  The light bends as a result.

B) The "Constant" speed of light actually refers to the maximum speed at which all electric energy propogates.  This "speed" will be slowed by outside factors like resistance but can never increase beyond the Constant.

Answer 3

yes, of course

Answer 4

The variable speed of light (VSL) concept states that the speed of light in a vacuum, usually denoted by c, may not be constant, for some reason. In most situations in condensed matter physics when light is traveling through a medium, it effectively has a slower speed. Virtual photons in some calculations in quantum field theory may also travel at a different speed for short distances; however, this doesn't imply that anything can travel faster than light. While it is usually thought that no meaning can be ascribed to a dimensional quantity such as the speed of light varying in time (as opposed to a dimensionless number such as the fine structure constant), in some controversial theories in cosmology, the speed of light also varies by changing the postulates of special relativity. A fundamental change to relativity is needed if c is changing because relativity shows that space and time are equivalent.

Answer 5

Nope, it is a universal constant.

Answer 6

The velocity of light varies from medium to medium depending upon their refractive index.

Answer 7

yes

Answer 8

Yes the speed of light varies from one media to the other.For example the speed of light in a vacuum is 3 X 10^8 m/s.However it is little less in air and quite less in other media.As the media gets denser the speed of light becomes lesser and lesser.The light that we see is comprised of seven visible[besides there are invisible waves of ultraviolet,infrared etc] colours v.i.z. violet,indigo,blue,green,yellow,orange and red.abrevated as VIBGYOR.Their speed is constant in vacuum but varies in other media.The best example is a prism which is made up of glass slabs and it seperates white light from the sun into its constituent colours.

Answer 9

The speed of light certainly varies when going through a material.  This has been known for a long time and causes light to bend when traveling into these materials.  Light will travel slower in any material, but in most materials, it is a very small change and the light still travels very fast.  But in the lab, there have been some experiments that have been able to make special materials and conditions where light slows down to tens of miles per hour (slower than a car on the freeway).  There have also been some experiments that claim to have sped up light, but the ‘faster than light’ experiments are always flawed experiments where the scientists got confused.

However, when someone says the speed of light, they usually mean ‘the speed of light in vacuum’, not the speed of light in a material.  In Einstein’s equation, E=mc^2, the c is the speed of light in vacuum.  This is a constant value that probably does not change.

There are some theories that propose a very slow change in fundamental constants, like the speed of light.  The most common fundamental constant that people think might be changing over time is the fine-structure constant, alpha, which is used in atomic and nuclear theory.  Alpha is proportional to the inverse of the speed of light, so if alpha changes, then there is a chance that the speed of light also changes.  So far, no one has observed alpha changing.  But since it would change so slowly, it is hard to see it change.  The best way to try to see alpha change is with atomic clocks, which are by far the most sensitive measuring devices that humans have.  Of course, they are not yet sensitive enough to measure a change in alpha.  So as atomic clocks get better, we may be able to see alpha changing, if it really is changing.  Until then, we can only theorize whether alpha or the speed of light changes over time.

Answer 10

i think that it is constant because every other speeds reference to the speed of light.