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Author: Subject: Gravitational wave paradox
Swinfi2
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[*] posted on 13-9-2020 at 13:07
Gravitational wave paradox


I know this isn't chemistry but I'm willing to bet more than a few have been keeping loosely up to date with this kind of thing.

I'm probably not the only one to notice but there seems to be either a paradox or at least a logical inconsistency in the conclusions drawn about gravitational waves and black holes.

Three "facts" that cannot imo all be true.
1) gravitational waves travel at the speed of light/causality.
2) gravitational waves are effected by gravitational lensing/spacetime curvature.
3) black holes devour spacetime at the speed of light/causality.

So... if gravitational waves travel at the speed of light, and follow the curvature of spacetime, shouldn't a black hole blink out of existence as soon as it forms because the force of gravity would be unable to escape.

Or the other explanation is that I have it wrong.
Anybody have any ideas?
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TheMrbunGee
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[*] posted on 13-9-2020 at 14:02


Think of gravity as dents in a 2D plane, one can combine dents forming larger dent. Dents themselves are not attracted, but masses giving the gravitational field fall into the dent. Gravity is not attracted by gravity, so the ripples forming in the plane by rapidly orbiting huge dents are not "sucked" back into the dent of the event. And the ripples will follow the plane including the dents.

It seems wrong to think of gravity exactly as force. And as something that can or cannot escape.

I Do not get why would black hole "blink out of existence", in a way, there is not much difference between an object with a mass that makes its escape velocity greater than c and an object a ton lighter. Many points at the scale of mass that gravity overcomes some atomic physical forces, and an object changes its behavior.

Pure speculation

I may have misunderstood Your problem!




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Chemetix
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[*] posted on 13-9-2020 at 16:36


I floated this idea on SM a while ago, ok similar, but the paradox I raised was this: If gravitation is mediated by particles, then they could not escape the event horizon of a BH to inform space time that there is mass. Therefore the stress-energy tensor in relativistic terms will not have a change in energy or momentum with respect to distance from a mass, which basically means you won't feel the mass behind the horizon. It's mass would be invisible to the rest of space. And yet, the curvature of space time must be mediated by particles otherwise the inverse square law of influence would not hold.

It leads me to assume that the way gravitation is mediated is more complicated than just a radiation of sorts from mass.

Magnetic force for example, we posit, comes from so called virtual particles, messengers that interact with the quantum state of an electron and convey information about the spin state to another electron at a distant point. Feynman diagrams use these ghost particles to be the source of all quantum electrodynamic causality. Their mass expressed as 4 momentum is tiny, being only the energy difference between the incoming state and outgoing state (the fact it is non zero seems a statement about the nature and causes of entropy) and their behaviour as a propagator is allowed to be off the mass-energy shell. If it gets too far from being on shell its range is increasingly diminished, which means exotic effects like signals from the future occur at incredibly small distances and time intervals. The terms on shell and off shell are the mass energy relationships that arise as an extension of the Minkowski 3 space.

But the point here is that these virtual particles can't violate the laws of physics, at least not at extended range. Signals must travel at the speed of light and remain Lorenz covariant. Exotic matter such as Tachyons have been proposed that would be in Minkowski terms, spacelike, rather than timelike 4 momentum on the energy momentum graph, and could be a way to convey information from the future, but no evidence for existence has been found.

So it remains to be found a mechanism that can propagate the force of gravity past the event horizon of a black hole. But the observable fact is that the mass of a black hole exists. So what could be an explanation of the curvature of spacetime due to mass and what could explain how it gets out of a black hole?

I have a hypothesis that doesn't rely on mass emitting any exotic particles and I think I can explain the nature of curved spacetime and the origin of the work function of a gravitational potential. Last time I tried to explain this on here it was too complicated for most to follow. It takes me about an hour in lecture format to explain it with all the necessary assumptions made about accepted and known physics to connect the dots.

But I'm a rank amateur at this, I'm sheepishly treading in waters where I know I'm out of my depth. It's just hard to talk myself out of this idea as being foolishly naive as there seems to be part of the puzzle dropping into place. This is a realm where even intellectual giants fear to tread, here be dragons.
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