-1

Any object which reaches close to a black hole accelerates towards it just like an apple accelerates towards earth when released from a height.

My question is that what happens when light reaches close a black hole does it accelerates and if it accelerates then its speed would become greater than 299,792,458 m / s which is a speed limit of anything in the universe.

So should it accelerate or not.

The Mathemagician
  • 954

2 Answers2

0

No, light does not accelarate. Light redshifts (or blueshifts, depending on observers location) in gravitational fields.

Kosm
  • 2,756
0

First off, note that acceleration does not direction correlate with speed. It is related to velocity, so light can in fact be accelerated by any gravitational source (gravitational lensing).

However, these effects just change the velocity vector direction, they do not change the speed of the light and they cannot. Light must never move faster than the physical limit of $299,792,458 m/s$.

So what happens when light is released near a black hole and travels directly towards it with not change in direction? As the photon falls into the gravitational well, the frequency changes, thereby changing it's energy proportionally to it's change in gravitational energy. This is what we see as "red shift" and "blue shift" when photos move away from or towards a gravitational source.

fhorrobin
  • 1,089