# Thread: Vision at the speed of light

1. Okay, here's the scenario: An object is rotating in space, let's say a cube.

If I were to travel at the speed of light away from the rotating cube, at the moment I interpret a point in its rotation...
Would the rotating cube actually appear motionless to me?

The same with sound:
If there's an object producing an oscillating sound, and I move at the speed of sound away from it
Would I hear a constant pitch? (assuming the sound waves never dissipate)

2.

3. According to General Relativity, light always moves at the same speed to the observer. Frame of reference does not matter.

Sound is subject to compression and expansion depending on relative speed of the source and listener.

4. As Archie stated, light is a constant relative in the universe, but sound is not. It is subject so compression and expansion of sonic waves, and this is how we come about the Dopler effect. Ever notice how a police siren coming towards you is higher pitched than when it moves away from you? The sound waves are being 'stretched' by the relative movement of the police car as it moves away from you, creating what out brain perceives to be lower resonance, or a lower pitch. The same happens as the car moves towards you. The relative movement between your ear and the police car changes, compressing the sound waves, lowing the sound wavelength, and creating a higher pitched sound. Try it yourself. Get a friend on a bicycle to ride past you at high speeds while blowing a whistle.

5. But yes, if you were travelling away from an object emitting a reciprocating sound at the speed of sound, and the sound did not dissipate, then this effect would be achieved. But it must also be noted that the sound boom created at those speeds, and the disruption of particles carrying the sound vibration towards you would probably make this particular factor extremely hard to scientifically measure.

6. You can't travel at the speed of light.

If a sound wave doesn't hit you, you won't experience it.

7. You can travel infinitley close to it in theory, through. Doing so would require infinite amounts of energy and power, and the universe simply doesn't contain the neccesary resources without the second and first laws of thermodynamics coming into play. However, as the speed of light is a constant at all speeds, then your vision would not really be altered - despite the fact that you are going infinitely close to the highest possible speed...

8. Firstly the light from the cube would get redder and redder as you accelerated. Eventually it would become infra red, so you would no longer see it.

Then, time would stop for you, if you moved away at the speed of light. ( not that you could ).
So you would be aware of nothing till you slowed, ( which couldn't happen either ).
But if it could, it would seem that you had travelled instantaneously into the future. So the cube would just instantaneously disappear.

The sound wave would be similar. The pitch would drop lower and lower till it stopped altogether, and you would be unaware of any sound till you slowed.

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