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Thread: Do black holes eventually shine? And does the grid size of space change over time?

  1. #1
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    Do black holes eventually shine? And does the grid size of space change over time?

    OK guys - I'm totally new here and have been digesting all the stuff about black holes, singularities, and what on earth space is made of for some time and do not have the intellect to link it all in my brain but I do have some questions and wonder if anyone can help me out?

    1. black hole densities, escape velocity and time dilation. So it takes light 1 million years to leave the core of the sun just due to bouncing about because matter is simply very tightly packed. In a black hole, matter (if there is a form of matter - unless its all energy - there must be mass of some type?) is even more tightly packed. Whatever the 'size' off a black hole - inside the event horizon the 'mass-stuff' is very dense. Now, could it just be that when a black hole forms from a supernova, it forms so quickly, that any light 'in the black hole' simply bounces about this dense 'mass' (similar to bouncing around in the sun) but takes even longer to pop out? As the mass is millions/trillions times denser than the core of the sun so takes billions/trillions times longer. AND furthermore, due to the effects of time dilation (not that I understand this either - but they say time slows down to a stop at a black hole), then the light might take billions/trillions of years to bounce around in the back hole and pop out only for billions times more of years to pass for us here watching with our telescopes. So, in a trillions of years or whatever this all works out to be, blacks holes formed so far will simply start to shine and light up the universe again when its all else has gone dark and cold and we will have an all new firework display similar to the cosmic dawn. So maybe the escape velocity is less than 'c' as when the black hole starts to shine, it cannot be greater than c?

    2. big bang, the entire mass/energy of the universe, cosmic expansion, grid-size of space. So, the universe started and it expanded. If space really is granular at the plank/string-sized level and there's a kind of 'grid' structure and size at whatever the smallest level is, then as space is expanding, has the size of these grids been expanding or the number of grids been increasing or both? Ie. is the size of each grid of space getting bigger or are we making more grids? Assuming the grids are not getting bigger (as it would be crazy to have a grid the size of a planet) then grids stay the same size and so have grids always been the same size - even at the time of the big bang? If they are the same size then are we creating more space? If there is no such thing as empty space then is energy of some kind created with this 'new' space' and as e=mc2 are we also creating Mass? If so, was Hoyle right (steady state theory that mass somehow is always being created) as well as the big bang theorist being also right? To conserve the net balance of the universe as zero, what is offsetting this space-energy-mass creation so we don't flout the 1st law? If the size of the grid of space is not changing then was it the same size at the big bang and was the whole of the energy and so mass of the current universe contained in it or was more mass and energy created as more space grids were created - and therefore we did not have a singularity but some amount of energy per came out of one grid space and more were created over a very short period of time creating more mass energy and space and this process has never actually stopped?

    Anyway - I wish I knew this stuff - I just read and think up these crazy questions.
    Last edited by slang; 2019-Apr-29 at 04:11 AM. Reason: fixed title

  2. #2
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    1. Light never leaves a black hole which is the origin of calling them black. Thus they never eventually shine.
    As far as we know, the matter at the center of a black hole is infinitely dense. There is no known physics that can stop matter from collapsing into a singularity (zero volume, infinite density). An expectation is that a quantum gravity theory will blur out the singularity to make the matter extremely dense.
    Time does not really stop at a black hole. What an outside observer sees is that light from in-falling matter gets more and more red-shifted as it approaches the event horizon. So we cannot see matter crossing the event horizon. However the matter falls as normal and ends up inside the event horizon.

    Black holes do have Hawking radiation so in a sense they "shine" all of the time.

    2. The sized of any hypothetical Planck grid possibly would increase.
    I cannot think of a reason why expansion of spacetime would stop at the Planck level. However the lack of a complete theory of quantum gravity leaves room for other behaviors, including that there is no such grid!

  3. #3
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    I think it's worth pointing out that black holes were predicted by the relevant math (of gravity etc), and then observations of various kinds started being made that confirmed their existence.

    Comments like "Now, could it just be that when a black hole forms ..." make it sound like the reverse; that we saw this black thing out there, and had to come up with an explanation for it.

    That's back to front. Any alternate explanation for why a black hole is black would have to account for the prediction of them - and the basis of that prediction.
    Measure once, cut twice. Practice makes perfect.
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  4. #4
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    Quote Originally Posted by Reality Check View Post
    .
    Time does not really stop at a black hole. What an outside observer sees is that light from in-falling matter gets more and more red-shifted as it approaches the event horizon. So we cannot see matter crossing the event horizon. However the matter falls as normal and ends up inside the event horizon.
    To clarify, the object falling in leaves its slowed image behind. From an infalling observer's point of view, they're just falling.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  5. #5
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    Quote Originally Posted by Top Banana View Post
    1. black hole densities, escape velocity and time dilation. So it takes light 1 million years to leave the core of the sun just due to bouncing about because matter is simply very tightly packed. In a black hole, matter (if there is a form of matter - unless its all energy - there must be mass of some type?) is even more tightly packed. Whatever the 'size' off a black hole - inside the event horizon the 'mass-stuff' is very dense. Now, could it just be that when a black hole forms from a supernova, it forms so quickly, that any light 'in the black hole' simply bounces about this dense 'mass' (similar to bouncing around in the sun) but takes even longer to pop out? As the mass is millions/trillions times denser than the core of the sun so takes billions/trillions times longer. AND furthermore, due to the effects of time dilation (not that I understand this either - but they say time slows down to a stop at a black hole), then the light might take billions/trillions of years to bounce around in the back hole and pop out only for billions times more of years to pass for us here watching with our telescopes. So, in a trillions of years or whatever this all works out to be, blacks holes formed so far will simply start to shine and light up the universe again when its all else has gone dark and cold and we will have an all new firework display similar to the cosmic dawn. So maybe the escape velocity is less than 'c' as when the black hole starts to shine, it cannot be greater than c?
    The reason that light cannot escape a black hole is simply that all paths through space lead to the centre. There is no path that leads out.

    The only model we currently have of black holes is General Relativity (GR). This says that all matter which falls into the black hole quickly reaches the centre and is crushed to a point. The is probably not accurate and we need a theory that combines GR and quantum theory theory to give us a better idea of what happens inside a black hole.

    But if matter were distributed evenly inside a black hole, the density would be pretty low. If you calculate the volume and mass for a large black hole, the average density can be less than that of water.

    2. big bang, the entire mass/energy of the universe, cosmic expansion, grid-size of space. So, the universe started and it expanded. If space really is granular at the plank/string-sized level and there's a kind of 'grid' structure and size at whatever the smallest level is, then as space is expanding, has the size of these grids been expanding or the number of grids been increasing or both? Ie. is the size of each grid of space getting bigger or are we making more grids? Assuming the grids are not getting bigger (as it would be crazy to have a grid the size of a planet) then grids stay the same size and so have grids always been the same size - even at the time of the big bang? If they are the same size then are we creating more space? If there is no such thing as empty space then is energy of some kind created with this 'new' space' and as e=mc2 are we also creating Mass? If so, was Hoyle right (steady state theory that mass somehow is always being created) as well as the big bang theorist being also right? To conserve the net balance of the universe as zero, what is offsetting this space-energy-mass creation so we don't flout the 1st law? If the size of the grid of space is not changing then was it the same size at the big bang and was the whole of the energy and so mass of the current universe contained in it or was more mass and energy created as more space grids were created - and therefore we did not have a singularity but some amount of energy per came out of one grid space and more were created over a very short period of time creating more mass energy and space and this process has never actually stopped?
    There is no evidence that space is granular or quantised in that way (producing a model based on that is one of the big challenges at the moment).

    However, if it were, then the size of the "granularity" would not change. In the same way that the number of light years, metres and millimetres increase between things, then the number of "space-quanta" would increase - things are just getting further apart.

    One possible explanation for dark energy is that it is the "cost" of space: as the universe expands there is more space and so more dark energy. (But as we don't yet know what dark energy is, beyond its effects, that may be premature.)

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