Sorry, I was referring GR and SR as it has become holy bible of physics. Any descent and you are excommunicated. It does not matter what kind of argumed someone will come up with. Einstein said that nothing can travel faster then light and that’s it.
I dont understand the details, but one thing puzzles me.
An outside observor sees infalling matter into a black hole slow down to a stop at the event horison (and its "information" be preserved, smeared over the event horison, as Hawkings has postualted recently). This implies that time, to an outside observor, at the event horison slows to a stop (matter is traveling at C). To the black hole then, the passage of time of the outside universe is instananeous, as it is to a photon. How can a black hole actually grow in mass beyond the event horison then, it hasnt got time to. Is the space inside the event horison empty?. Is all its mass smeared over the event horison?.
Hi Fred
For any spinning black hole, there exists an invisible boundary, known as the stationary limit. Within the stationary limit, nothing can escape being dragged around the black hole - unless it can travel faster than light, currently an impossible condition. At the limit itself, a visitor could avoid being dragged around (and remain stationary), providing that he could travel at the speed of light.
Now, if you can't maintain the speed of light, its off to the event horizon and the singularity.
And then it's "spaghettified", "crushified" and nullified for you
LOL, but how "nullified" ?, is its "information" preserved?.I may have this wrong, but I understand it must be or some fairly important Physics theories fall apart ,or is that covered in "Hawkings radiation") ?.
How can a black hole actually grow in mass beyond the event horison then, it hasnt got time to. Is the space inside the event horison empty?. Is all its mass smeared over the event horison?.
Fred,
A black hole cannot grow beyond the event horizon because the horizon is a function of the mass of the black hole. As the mass of the black hole increases the event horizon will also increase. Conversely as a black hole evaporates the event horizon will shrink.
Because information cannot be retrieved beyond the event horizon what happens beyond that boundary is speculation.
LOL, but how "nullified" ?, is its "information" preserved?.I may have this wrong, but I understand it must be or some fairly important Physics theories fall apart ,or is that covered in "Hawkings radiation") ?.
No preservation of information and as you approach infinite gravity and zero volume, all known laws of physics will break down as will space time.
So the current thinking goes.
As for Hawking Radiation the current thinking is about 43% of the mass escapes as radiation, so black hole wins by a large margin, bearing in mind that mass and energy are one and the same thing.
Or so the thinking goes!
Sorry, I was referring GR and SR as it has become holy bible of physics. Any descent and you are excommunicated. It does not matter what kind of argumed someone will come up with. Einstein said that nothing can travel faster then light and that’s it.
Thanks for clearing that up.
One point to remember however.
Einsteins theories although incomplete, have been thoroughly tested and proven beyond any doubt although they may be replaced by more complete theories in the future. String theory looks like it may be the contender but as yet cannot be tested in any form whatsoever. So until then, Einsteins theories reign supreme.
No preservation of information and as you approach infinite gravity and zero volume, all known laws of physics will break down as will space time.
So the current thinking goes.
As for Hawking Radiation the current thinking is about 43% of the mass escapes as radiation, so black hole wins by a large margin, bearing in mind that mass and energy are one and the same thing.
Or so the thinking goes!
43%?, that implies black hole remnants last for ever. I read somewhere black holes evaperate altogether in something like 10*250 years?. 43% over what, a period of time?.
And, if information is not preserved, doesnt that stuff causality. I thought if time was reversable, you could recreate any state in the past?.
Anyway, there's nothing wrong with what you have said except for this. Even though the Sun's gravitational well is much larger than the Earth's, we are subject to a greater acceleration towards the centre of the Earth than we are to the Sun.
I agree with you completely on this part: we are subjecft to a greater acceleration towards the centre of the Earth than we are to the Sun (by about 3 orders of magnitude).
I have never said otherwise. This is why I was careful to refer to "gravity well" and not "gravitational acceleration" or "force".
Escape velocities give a good feel for the size of the gravity wells:
Escape velocity of Earth = 11.2 km/s
Escape velocity of Sun = 618 km/s
Quote:
Originally Posted by renormalised
Sure, as part of the Earth system, we are in free fall about the Sun and don't feel the Sun's curvature of spacetime, but that's precisely the point. We are much closer to the Earth than we are to the Sun and from our vantage point, the curvature of spacetime the Earth generates is more intense than the Sun's. Hence we don't go floating off into space towards the Sun.
This is not the reason we don't fall off the Earth though. As the Earth is in free-fall around the Sun, we don't feel the gravity of the Sun directly. We do feel it's massive curvature of the space-time in our vicintiy through tidal effects.
43%?, that implies black hole remnants last for ever. I read somewhere black holes evaperate altogether in something like 10*250 years?. 43% over what, a period of time?.
And, if information is not preserved, doesnt that stuff causality. I thought if time was reversable, you could recreate any state in the past?.
Time required for a blackhole to evaporated is governed by it's mass.
"As Doug yells in wild abandon, his trusty starship dives headlong across the event horizon of the black hole, never to return. Only, Doug gets spat out as a virtual particle."
"As Doug yells in wild abandon, his trusty starship dives headlong across the event horizon of the black hole, never to return. Only, Doug gets spat out as a virtual particle."
Only to discover .... he'll never get there Doh !!!
Only to discover .... he'll never get there Doh !!!
Then realises the answer to the question about life, the universe and everything isn't 42..... it's the SQRT(-0/2pi x 10^-22)/v x G.... whatever that is!!!!
43%?, that implies black hole remnants last for ever. I read somewhere black holes evaperate altogether in something like 10*250 years?. 43% over what, a period of time?.
And, if information is not preserved, doesnt that stuff causality. I thought if time was reversable, you could recreate any state in the past?.
Sorry about the delayed answer, i was delayed by the black hole called work.
As i said earlier the radiation emitted by blackholes is about 43% of the in falling matter.
Matter has two varieties matter and antimatter. When these twins meet they annihilate with 100% mass to energy conversion.
Now if matter crosses the event horizon without its twin antimatter, then the antimatter outside the event horizon will not be able to pop out of existence via the annihilation process. It then gets promoted from virtual particle to real particle and this is the essence of the Hawking radiation. The result of this loss of energy is the weakening of the black holes gravitational field as the energy of annihilation cannot occur within the blackhole. This is the 43% deficit. Now obviously as time progresses the gravitational field gets weaker and weaker until eventually the blackhole evaporates. (as the gravitational field gets weaker, less matter falls in so its a compounding problem)
