romesh

So what you actually said implies that we can travel faster than the speed of light (in which the speed of light i less than c;for example we can travel at a speed >speed of light in water) in some medias. Correct me if i am wrong.

I have a question regarding refraction. I want to know the reason for the decrease in the speed of light in mediums like air, water, kerosene etc... If you could help me I would also like to know the reason as to why some mediums are opticaly rarer and some opticaly denser.

I have a query. I want to know that is the restricted speed for any object according to special relativity is the speed of light or it is 299792458 ms-1 The reason for this query is that I have studied that light travels at different speeds in different mediums.

But the light spot isn't a material object unlike the stars. The spot is just a geometric spot which is moving. And the restriction to the speed of light applies to general relativity as well. This is baseless. You mean to say that if we keep on accelerating an object then, we could reach the speed of light c or even beyond it! Now if we stop accelerating, our uniform speed can come c or even more than c!

You got my question right IM Egdall. But Einstein's special relativity restricts speed of any object by speed of light. The stars which are far enough from the earth would certainly revolve around the earth at or greater than c if we take earth as the frame of reference. Let me explain my question further. If there is a star, 2 light years away from the earth, then it has to complete the revolution,of 2*3.14*2 light years, around the earth in 24 hrs. This star would definately cross the restricted speed of c. How can this phenomenon be explained?

I have aquestion regarding the topic. We say that the earth rotates on its axis which causes a bulge in its shape. Conversely we can say that the gravitational effects of the motion of whole of the universe causes the bulge. But will not the distant stars of the universe cross the restricted speed of light c in the process? How can we explain this phenomenon?