Why speed of light is constant with respect to any observer in free space?

Answer 1

It looks like no one has really understood your question.

Well the above question that the speed of light is independent of the motion of the observer, is really a basic postulate of the theory of special relativity.

This has not been proven only in theory by solving Einstein's equations but also in practice through experiments. Two scientists Michelson and Morley set up an experiment to attempt to detect the ether, by observing relative changes in the speed of light as the Earth changed its direction of travel relative to the sun during the year. To their surprise, they failed to detect any change in the speed of light.

The reason is that when something travels at the speed of light starnge things happen like time and space dilation. Time and space dialates and thus the observer always observe a constant speed of light independent on his motion.

Answer 2

I can answer your question with an analogy. Think of the speed of light in this way, and you may be able to understand it: Instead of thinking of light as being emitted as part of a medium (space), think of it like the waves that are created on a lake or a pond of still water. Imagine you are standing on the edge of a pond of water and you toss a pebble into the pond. From the point at which the pebble strikes the surface waves move outward in concentric circles - that is like light being emitted from a source. The concentric circles of waves will move outward at a given speed and this speed can be measured and will always be the same speed. Now, imagine that instead of standing on the edge of the pond, you are flying toward the pond in a small plane. As you start to pass over the pond, you toss a pebble out the window into the pond. The pebble will now strike the surface not from a stationary observer, but from a moving observer. When the pebble strikes the surface of the pond, the waves move outward in exactly the same way, same speed etc. There is no difference if you are moving or standing still. This is how light always travels at the same speed in a vacuum, no matter how the observer is moving or not moving. Does that help?

Answer 3

I suspect that in regions of reality where the speed of light were drastically different or light does not exist at all beings such as ourselves could not evolve to answer the question. Now why is the speed of light constant? Perhaps regions containing observers with constant light speed are more common than regions containing observers with variable light speed. In any case I suspect the answer depends on the anthropic principle.

Answer 4

Maxwell's equations of electromagnetism (which are probably the most accepted physical equations in the history of science) show that the speed of electromagnetic radiation is independant of the source emitting it. However I will not go into the details here.

Just realise that they come as a consequence of consistently proven electromagnetic laws.

But, ifyou want to find out more:
http://en.wikipedia.org/wiki/Speed_of_light
http://en.wikipedia.org/wiki/Maxwell's_equations


ADDITIONAL: Sporadic, you are not answering the question. The theory of Special Relavity came from the assumption that light is constant in a fixed inertial reference frame, as shown by Maxwell. This is not a reason for light to be constant. Michelson and Morely SHOWED that light moved at a constant speed but they did not give a reason. The question was WHY does light move at a constant speed.

Answer 5

Perhaps no one really knows why the speed of light is constant for a given observer. We do know that light travels at the fixed speed of light as photons and as you increase the energy level the light wavelength shortens. For example ultraviolet light has shorter wavelengths than infrared light and is more energetic and penetrating. Infrared (heat lamps) warms you and ultraviolet (tanning lamps) can burn you. To make light go faster you would have to add more energy but that would only shorten the wavelength. Photons are given up by electrons orbiting atoms and molecules when the electrons fall to less energetic orbits producing photons of long or short wavelengths depending on the excess energy of the electron being converted to light. It is similar to short cars and long trucks all traveling at the speed limit on a busy highway.

Answer 6

Space is almost a perfect vacuum, so light travels the fastest through a vacuum and at the same speed.

Answer 7

I think its because its speed is maximum speed allowed in the universe. I don't know if that answers it.