That's what i want to know as well. Well see, i'll try to keep it short(i don't like long posts anyway).
Imagine you are carrying in your hands a very powerful laser torch. A laser torch so powerful that it could send a beam of visible light to Mars.
Actually this can already occur. Lasers in space have no distance limitation. We can already use a laser to measure the distance (range) to the moon (by essentially bouncing it off the moons surface). The only problem is that the light from the laser spreads out logarithmically in area the further in distance it reaches. So that when the beam hits the laser reflector on the moon, the area the photons from the laser hit is wider than what it was before it left the Earth. Since Mars is further away, this area hit by the photons from the laser cover even a larger area and are going to being absorbed by Mar's atmosphere. Therefore these photons will not bounce back and will not be detected by any Earth based light detection system.
You switch on your laser torch and you point it towards the sky and hold it steady. After a minute, the light will reach Mars.
It takes about 3 minutes for light to reach Mars from the Earth at the closest proximity between the two.
You look through your 2000x magnifying telescope and see that the beam has hit Mars. Then you sweep your hand and the ray goes all the way to the other end of the horizon.
What horizon? The horizon of the Earth?
What happens with the ray? It follows your hand and because light travels only in straight line, the light that shone Mars will have to move FTL to the other end of the horizon, which might be pointing to Jupiter for example. If it doesn't, then light will have to bend which is impossible as far as we know.
Um, no. Light cannot go faster than the speed of light. That is an oxymoronic statement. Light follows the shortest path between two points on the curvature of spacetime. If spacetime is warped because of gravity than it takes the shortest path which will make it seem to a static observer i.e. an astronomer looking through a telescope, that light bends. However, it is not light that is bending but it is the very fabric of spacetime itself due to gravity. The light is actually in multi-dimensional, Einsteinian (as opposed to Euclidian geometry) geometry taking the straightest and shortest path between two points.
Edited by DevilsAdvocate, : No reason given.
For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.Dr. Carl Sagan
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