Gravity And The Speed Of Light

[Dubbelosix]

Relativity states that light is always measured at light-speed in a vacuum. In relativity, the dilation of spacetime around a black hole ensures that light finds it difficult to escape and impossible to escape past the horizon. Since we cannot measure anything past the horizon, would someone outside the black hole measuring light travelling from it, find it moved at the appropriate speed of light?

 

One explanation is that the length in which light is having to travel will increase, but the speed of light remains the same. It's difficult then how this would not produce the illusion that light was seen to travel slower to an observer. Maybe the key word has already been used, its an illusion. Alternatively, someone on the internet said:

 

''Its not the light the changes at a black hole, its time, time slows down. In a black hole time slows down so much that light even at its very high speed cannot get anywhere. 

Reference https://www.physicsforums.com/threads/does-light-slow-down-relativistic-near-a-black-hole.435785/'

 

Of course, if time slows down, how does this effect the light, since light has no frame of reference and experiences no time pass at all? Time hasn't slowed down to an observer far from the black hole, so this answer doesn't satisfy the postulates of relativity. Maybe time has slowed down but this is inconsequential for a photon, but a space dilation is no trivial issue for light when measured by a distant observer. 

 

As I said, its hard to wrap around why the speed of light would not appear to have slowed down to some observer outside of the black hole, since the dilation of the distance ensures that it now has to travel longer distances to try and escape the gravitational effects. A different poster from the same site said:

 

''Not everyone says that light "stays the same speed"; for a distant observer, light progresses slower near a black hole than further away from it. Apart of that, the speed of light in vacuum is not known to be affected by temperature; and indeed, that concept doesn't make much sense in vacuum!

Reference https://www.physicsforums.com/threads/does-light-slow-down-relativistic-near-a-black-hole.435785/'

 

So in this sense, one poster has at least recognized that the speed of light will be measured to move slower in the gravitational field in a local sense - an observer far from the source definitely [will] measure the speed of light to be that of the vacuum. Whether or not the person measures the light to move slower in his frame, perhaps the key out of the paradox remains simply that the photon is still moving at light speed, regardless of the increase of distances due to dilation.

[Vmedvil2]

Relativity states that light is always measured at light-speed in a vacuum. In relativity, the dilation of spacetime around a black hole ensures that light finds it difficult to escape and impossible to escape past the horizon. Since we cannot measure anything past the horizon, would someone outside the black hole measuring light travelling from it, find it moved at the appropriate speed of light?

 

One explanation is that the length in which light is having to travel will increase, but the speed of light remains the same. It's difficult then how this would not produce the illusion that light was seen to travel slower to an observer. Maybe the key word has already been used, its an illusion. Alternatively, someone on the internet said:

 

''Its not the light the changes at a black hole, its time, time slows down. In a black hole time slows down so much that light even at its very high speed cannot get anywhere. 

Reference https://www.physicsforums.com/threads/does-light-slow-down-relativistic-near-a-black-hole.435785/'

 

Of course, if time slows down, how does this effect the light, since light has no frame of reference and experiences no time pass at all? Time hasn't slowed down to an observer far from the black hole, so this answer doesn't satisfy the postulates of relativity. Maybe time has slowed down but this is inconsequential for a photon, but a space dilation is no trivial issue for light when measured by a distant observer. 

 

As I said, its hard to wrap around why the speed of light would not appear to have slowed down to some observer outside of the black hole, since the dilation of the distance ensures that it now has to travel longer distances to try and escape the gravitational effects. A different poster from the same site said:

 

''Not everyone says that light "stays the same speed"; for a distant observer, light progresses slower near a black hole than further away from it. Apart of that, the speed of light in vacuum is not known to be affected by temperature; and indeed, that concept doesn't make much sense in vacuum!

Reference https://www.physicsforums.com/threads/does-light-slow-down-relativistic-near-a-black-hole.435785/'

 

So in this sense, one poster has at least recognized that the speed of light will be measured to move slower in the gravitational field in a local sense - an observer far from the source definitely [will] measure the speed of light to be that of the vacuum. Whether or not the person measures the light to move slower in his frame, perhaps the key out of the paradox remains simply that the photon is still moving at light speed, regardless of the increase of distances due to dilation.

 

Light cannot escape a BH in the form of light but virtual photons it can but there are spots or holes in the singularity caused by spin which allow it to escape as hawking radiation, nonetheless in most areas of the BH's event horizon time goes to an infinity in length and space contracts to a infinity making it impossible for the photon to travel any distance, light does definitively feel the effects of gravitational attraction toward a blackhole and also time dilation for the photon can even have time go slower which is shown by the trapped light moving experiment the movement of the photon can slow down by the effects of motion, in this case the motion of gravitational attraction toward the BH, so it becomes infinitely trapped adding to the mass of the BH. The light trapped in a box experiment can easily show what it is like for a photon in a BH with gravity crushing the space around it, but the photons become stuck in place from the length of space being infinitely small, there is your answer.

 

Edited July 10, 2018 by VictorMedvil

[Super Polymath]

Light cannot escape a BH in the form of light but virtual photons it can but there are spots or holes in the singularity caused by spin which allow it to escape as hawking radiation, nonetheless in most areas of the BH's event horizon time goes to an infinity in length and space contracts to a infinity making it impossible for the photon to travel any distance, light does definitively feel the effects of gravitational attraction toward a blackhole and also time dilation for the photon can even have time go slower which is shown by the trapped light moving experiment the movement of the photon can slow down by the effects of motion, in this case the motion of gravitational attraction toward the BH, so it becomes infinitely trapped adding to the mass of the BH. The light trapped in a box experiment can easily show what it is like for a photon in a BH with gravity crushing the space around it, but the photons become stuck in place from the length of space being infinitely small, there is your answer.

 

No length contraction of the photon means the photon doesn't have to cover as much of a distance as time dilates so c remains the same, though it appears to be moving slower from the frame of reference of an outside observer who is experiencing time & space at a normal relation to one another but it's not possible to actually see that light unless you can reflect QE's carrier of information (the tachyonic pilot wave) off those photons