Imagine- a torch traveling at the speed of light backwards, if it was on would you be able to see the light???

Question

torch traveling at speed of light-
would the speed of the torch cancel out the speed of the light given of by it?

if light didnt travel at the speed of light would you still see it (if it was not moving at all maybe?)

Answer 1

Assuming that you mean very, very close to the speed of light, then yes you would still "see" the light. It would be extremely red-shifted and thus probably no longer within the visible light portion of the electromagnetic spectrum, but the photons would still propagate and may still be detected. And the photons would still be moving at light speed away from wherever the torch is when the photon was emitted; they cannot speed up nor slow down.

If you mean exactly the speed of light, then the question is moot. For objects with mass, the speed of light is a limit not an achievable speed, otherwise at that speed its length (in the direction of travel) reaches zero and its mass reaches infinity. Photons of electromagnetic energy can (and always) travel at light speed because they have no mass, except of course for their energy of momentum.

Answer 2

The speed of light is constant, regardless of the speed of the object emitting the light.

None the less, you won't be able to see the light. Doppler shift and relativistic effects would change the frequency of the light so low you couldn't even hear it, let alone see it.

The formula for Doppler shift is:

f' = f [c/(c+v)] where f' is the observed frequency, f is the actual frequency, c is the speed of light, and v is the velocity of the light source.

If the torch were emitting green light (a frequency of around 540 x 10^12 Hz, or 540 THz), the observed frequency would be half that (ignoring relativistic effects in the change in reference). A frequency of 270 x 10^12 Hz would be in the far-infrared region of the electromagnetic spectrum, which is outside the range that humans can see.

In practice, you would need to take the effects of relativity into consideration. The net effect would be to reduce the observed frequency to 0 Hz (i.e. - it would take an infinite amount of time for the next photon of light to be EMITTED FROM THE TORCH, even though all photons would travel the speed of light once they were eventually emitted).

Answer 3

In a short answer, yep. Strange but true, it doesn't make any difference whether it is approaching you or going away, the speed of the light from a given source is exactly the same. However, there is such a thing as a doppler effect. In the same way that the horn on a train approaching you has a higher pitched sound than one going away from you, light from a source approaching you will have a higher frequency than one going away from you even though the speed of the light will be exactly the same. This is called the red/blue shift when applied to light coming from a light emitting celestial body and can be used to determine whether it is approaching, receeding or staying relatively constant in respect to a given point in space.

Answer 4

Apparently it is impossible for anything other than light to travel at the speed of light. So whilst the light from the torch would do so the torch itself could not.

Answer 5

if the torch was traveling backwards at the same speed as light it would not be visable..does light travel at 368,000 miles a second i think im a bit in the dark on that one

Answer 6

Yes, the colour would have a red ting but yes and If you could measure the lights speed you would get a reading of 186,000 miles per second.

Answer 7

Assuming the light was still in the visible spectrum, you would definitely see it, but the torch wouldn't physically be where your eye tells you it is.

Answer 8

The speed of light is constant regardless of the speed of its propagation. Its colour will change though.

Answer 9

If it was coming at me, no.

If it was going from me, yes.

if it was moving at an angle, eventually but by a displacement.