Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jeffreyH on 09/12/2013 18:59:21
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Using mathematics we can show that light cannot escape a black hole. We can also show that ordinary matter can never approach the speed of light. The key here is gravity. If we impart enough energy to mass that it can approach the speed of light then the mass increases. If the mass increases then in theory so should its gravity. We could think of length contraction at nearing light speed in a similar way to that experienced around a collapsed mass where the gravity is concentrated. There is no difference between length contraction due to velocity and due to that under gravitational as they are both uni-directional and involve momentum. We could argue that in the situation where mass could attain light speed then the light is unable to outrun the mass. If this moving frame were observed as if it were a frame at rest it bears a striking resemblance to that inside an event horizon. The question is what does this tell us about the role of light in the definition of gravitation?
Addendum. Also consider a mass that had reached light speed and which generated a photon from within its own mass. How is this different from a black hole? This photon will never be able to leave the mass that generated it barring some other force acting upon the enclosing mass.
This also re-raises the question should it be easier to accelerate a black hole to light speed than any other form of matter? In this scenario what would happen to the gravitation contained within the black hole?
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Using mathematics we can show that light cannot escape a black hole.
Math can’t show anything whatsoever. Using mathematics we can show that general relativity predicts that light cannot escape a black hole
We can also show that ordinary matter can never approach the speed of light.
Any and all matter can approach the speed of light. In fact it came come as close to it as we’d like it to.
The key here is gravity.
Not at all.
If the mass increases then in theory so should its gravity.
If that’s all that’s present then that’s true. However there are other sources of gravity which when present and significant enough can also help to increase gravity or act to decrease it.
There is no difference between length contraction due to velocity and due to that under gravitational as they are both uni-directional and involve momentum.
They’re very different in fact.
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Using mathematics we can show that light cannot escape a black hole.
Math can’t show anything whatsoever. Using mathematics we can show that general relativity predicts that light cannot escape a black hole
We can also show that ordinary matter can never approach the speed of light.
Any and all matter can approach the speed of light. In fact it came come as close to it as we’d like it to.
The key here is gravity.
Not at all.
If the mass increases then in theory so should its gravity.
If that’s all that’s present then that’s true. However there are other sources of gravity which when present and significant enough can also help to increase gravity or act to decrease it.
There is no difference between length contraction due to velocity and due to that under gravitational as they are both uni-directional and involve momentum.
They’re very different in fact.
OK instead of approach the speed of light I should have said reach the speed of light. Yes Pete I also should have said predict instead of show. On the length contraction I have to disagree strongly. You are wrong.
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"Addendum. Also consider a mass that had reached light speed"
Why?
Nothing can reach light speed.
"This also re-raises the question should it be easier to accelerate a black hole to light speed than any other form of matter?"
No, it's impossible with a black hole or an electron or whatever.
"There is no difference between length contraction due to velocity and due to that under gravitational "
Still wrong.
I can measure the contraction of a meter rule under gravity, here on earth.
But I can't, within my own frame of reference, measure the contraction due to special relativity.
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"Addendum. Also consider a mass that had reached light speed"
Why?
Nothing can reach light speed.
"This also re-raises the question should it be easier to accelerate a black hole to light speed than any other form of matter?"
No, it's impossible with a black hole or an electron or whatever.
"There is no difference between length contraction due to velocity and due to that under gravitational "
Still wrong.
I can measure the contraction of a meter rule under gravity, here on earth.
But I can't, within my own frame of reference, measure the contraction due to special relativity.
Theoretically a mass cannot reach light speed. We have no empirical evidence to confirm this under all conditions.
Black holes trap light so have a special relationship to it, the properties of such objects are not well understood.
The last point is debatable.
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Well physics use particle accelerators. There you can confirm it, accelerating particles. The energy needed to reach the speed of light is 'infinite'. The universe itself can't reach such a energy even theoretically, as I gather. You can see all sorts of surprising things confirming the relation between 'energy' and mass/matter there too, as energy making a particle, etc. It's also lead, or just confirmed, to the idea of 'symmetry breaks', in where one expect the universe to have had different 'regimes', dependent on temperature (energy), creating different types of universe and particles.
And light is fairly well understood, as are black holes, outside a event horizon. The arguing today seems more a question of whether a singularity, really, can be consistent with some sort of 'center' of 'infinite mass' in a non dimensional point (as I think then, just as we have non dimensional particles existing), or if it can be defined to some other type of 'degenrated' mass, as particles existing.