Question: How does gravity affect the speed of light in a black hole?

In summary, the conversation discusses the effects of gravity on light, particularly in the context of black holes. It is noted that light, being a massless particle, does not speed up due to gravity and instead follows a curved path towards the center of the black hole. The concept of gravitational redshift is also introduced. It is then explained that in general relativity, gravity is not a force but rather the curvature of space-time, and light follows this curvature just like any other object.
  • #1
boredjavi
10
2
i don't know much about the subject but since I've gotten interested in it there is something that has been on my my mind.

if light would pass through the event horizon in a black hole the gravity would be to strong for it to escape. since it can't escape it would be pulled down to the point of singularity of the black hole. my question is that would the force of gravity pulling down on light be able to actually speed the light up possibly faster then the speed of light?
 
  • Like
Likes Mr.maniac
Astronomy news on Phys.org
  • #2
Light is a massless particle. Though it exhibits some particle properties (duality of light), a photon has no real mass. Because of this, photons do not follow everything that particles with mass do. One of these is speeding up due to gravity. In a black hole, the photon's path with bend and spiral due to the gravity of the black hole until it reaches the center but not speed up.

The interesting thing that happens is that the photon will lose energy when going towards the event horizon and eventually become invisible once it reaches this boundary (gravitational redshift). But the photon itself will never go faster than c.
 
  • Like
Likes Mr.maniac
  • #3
thank you for that! if light doesn't have any mass how is it that it can be bent or made spiral because of gravity?
 
  • Like
Likes Mr.maniac
  • #4
Welcome to PF!

Hi boredjavi! Welcome to PF! :wink:
boredjavi said:
thank you for that! if light doesn't have any mass how is it that it can be bent or made spiral because of gravity?

In general relativity, there is no force of gravity … "gravity" is just the curvature of space-time.

Light (like everything else) follows the curvature of space-time. :smile:
 

1. What is the speed of light in a blackhole?

The speed of light in a blackhole is the same as the speed of light in a vacuum, which is approximately 299,792,458 meters per second. However, within the event horizon of a blackhole, the gravitational pull is so strong that light cannot escape, making it appear to have no speed.

2. Can the speed of light be exceeded in a blackhole?

No, the speed of light is a fundamental constant in the universe and cannot be exceeded in any circumstance, including within a blackhole. The immense gravitational pull of a blackhole may distort the perception of time and space, but the speed of light remains constant.

3. How does the speed of light in a blackhole affect time?

The intense gravitational pull of a blackhole can create a phenomenon known as time dilation, where time appears to slow down for an outside observer. This means that time moves slower for an object approaching a blackhole than for an object further away from it. However, the speed of light remains constant, regardless of this time dilation.

4. Is the speed of light in a blackhole the same in all directions?

Yes, the speed of light is isotropic, meaning it is the same in all directions. This holds true even within a blackhole, where the intense gravitational pull may cause space to appear distorted. However, the speed of light remains constant in all directions.

5. Can anything escape the speed of light in a blackhole?

No, nothing can escape the speed of light in a blackhole. The intense gravitational pull of a blackhole is so strong that even light, which is the fastest thing in the universe, cannot escape it. This is why blackholes are often referred to as the "point of no return."

Similar threads

  • Astronomy and Astrophysics
Replies
6
Views
1K
Replies
14
Views
2K
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
10
Views
1K
  • Astronomy and Astrophysics
Replies
27
Views
3K
  • Astronomy and Astrophysics
Replies
5
Views
1K
Replies
5
Views
1K
  • Astronomy and Astrophysics
Replies
7
Views
3K
  • Astronomy and Astrophysics
2
Replies
43
Views
8K
  • Special and General Relativity
2
Replies
62
Views
3K
Back
Top