Question related to physics?

Question

We all know that the speed of light is constant no matter from what frame of reference you see it. I mean even you travel with the speed 100000m/s you will see the speed of light 3*10^8m/s. But what is the property of light that its speed always remains constant which is not in the case of bodies like cars. Did Einstein give any explanation for it

what i meant by the question was that if you are travelling in a spaceship travelling at 75000m/min and if you see a space ship travelling at 85000m/min who would see its speed 75000+85000m/min. however this is not the case with light. u will always see its speed 3*10^8m/s. why is that

Answer 1

The constancy of the speed of light is a consequence of the principle of relativity. This idea is that the laws of physics must be the same for all observers, no matter their state of motion. This is a convenient thing--the same physical laws always apply.

It so happens that the speed of light is a consequence of the theory of the electromagnetic field, ie, the speed of light in a vacuum is a physical law--hence it cannot vary no matter who measures it.

Answer 2

Actually the speed of light is not a constant. It is only constant while it is in a specific medium, and it is a measure of how quickly the medium can transfer energy. Think refractive index - if light passes through water it slows down and is bent - same thing in a prism and it is even slower here on earth than it is in space.

Light can also be bent around objects like our sun by immense gravitational fields (as Einstein predicted) and, just recently, materials were discovered that actually transmit light faster than 'the speed of light'. these materials are said to have a negative refractive index - the light exits the material Before it enters. Amazing!!!

I hope this helps...

Cheers,

Answer 3

Even before Einstein’s special theory of light, all knew that the speed of light is 3x10^8 m/s in vacuum.

The speed of light coincides with the theoretical value calculated from permittivity of free space and permeability of free space.

Further, light is transmission of energy and it is not a matter which can be accelerated to the extent we apply a force.

Not only light, all the electro magnetic radiation is transmitted with this speed.

This is the only way in which energy as in the form energy is transmitted.

Once the energy is transmitted from a source, it is transmitted with this speed.

The energy is full of kinetic energy and has no potential energy.

Once the light passes through a material medium and comes out of the medium and enters again vacuum, it moves with its original speed.

This is not the case with matter.

Thus even before Einstein’s special theory of light, all knew that the speed of light is 3x10^8 m/s in vacuum and is constant and there is no way to change its speed.

But what is the specialty in special theory is that the speed of light is independent of the speed of the observer and hence the fundamental quantities which were once thought as absolute is changed to be relative to the speed of the observer.

Answer 4

No, the speed of light (in a vacuum) is a fundamental constant. Einstein used it as a starting off point for his theories. We can show experimentally that light has no preferred reference frame (Michelson-Morley) *therefore* we infer Special Relativity from that.

We don't know *why* light has a constant speed, or why it is the particular speed, just like we don't know why an electron has mass, or why Plank's constant is the size it is. It just *is*.

Answer 5

there is not resistance and or friction involved...so the spped is nearly constant.

It's 3*10^8 m/s spped of light is based in a vacuum. It's speed changes a little tiny bit on other medium that we don't even care anymore because the change is too small!