PDA

View Full Version : Yet another blackhole question. How can gravity escape EH?



WaxRubiks
2017-Feb-05, 10:28 AM
Take a black hole and a star in orbit around each other.

The BH is moving, so it must be generating new warpage of space, as it goes around. But how can it generate new warpage if gravity cant escape, and we saw from the other thread that gravity progates along null paths in the same way that light does, so if light cant escape the event horizon, how can the mass within the EH warp any NEW space time as it bumbles around its orbit?

grant hutchison
2017-Feb-05, 12:57 PM
In the previous thread the argument came down to gravitons. In a graviton theory of gravity, the exchanged gravitons would be virtual gravitons, which (like virtual photons) are so poorly localized they don't care about the event horizon.

Grant Hutchison

Cougar
2017-Feb-05, 03:17 PM
But how can it generate new warpage if gravity cant escape....

Apparently, gravity escapes.

Noclevername
2017-Feb-05, 05:17 PM
Last time it was asked: https://forum.cosmoquest.org/showthread.php?162787-black-hole-confusion

WaxRubiks
2017-Feb-05, 05:26 PM
But virtual particles arent real. And arent constrained by reality....the similar way imaginary numbers arent constrained.

Noclevername
2017-Feb-05, 05:28 PM
But vitual particles arent real. And arent constrained by reality....the similar way imaginary numbers arent constrained.

But virtual particles are "not-real" in a different way than flying unicorns are not-real. More like half-real. VPs have physical effects, so they're real in that sense.

WaxRubiks
2017-Feb-05, 05:32 PM
But virtual particles are "not-real" in a different way than flying unicorns are not-real. More like half-real. VPs have physical effects, so they're real in that sense.but which half? The opposite half to the half that ignores the reality of physics?

Noclevername
2017-Feb-05, 05:45 PM
but which half? The opposite half to the half that ignores the reality of physics?

They are part of physics. They are, in fact, fundamental to physics, as the carriers for forces.

grant hutchison
2017-Feb-05, 05:46 PM
Virtual particles don't ignore the reality of physics - they're a product of the reality of physics, specifically Heisenberg's Uncertainty Principle.
If you claim that they're not real, then you're the one ignoring the reality of physics.

Grant Hutchison

WaxRubiks
2017-Feb-05, 06:01 PM
So do these virtual particles travel at c, but they dont follow a null geodesic path out of the black hole?

Shaula
2017-Feb-05, 06:04 PM
Virtual particles don't ignore the reality of physics - they're a product of the reality of physics, specifically Heisenberg's Uncertainty Principle.
If you claim that they're not real, then you're the one ignoring the reality of physics.
Virtual particles have some counter-intuitive properties - but that is essentially because they are an attempt to describe quantised field interactions in terms of a discrete particle model. The model doesn't fit what QFT is actually predicting so you get these apparent deviations from what you would expect of a simple particle model.

So rather than people saying that they 'ignore' physics or behave arbitrarily it is worth bearing in mind that they are a simplified model that don't entirely capture the underlying field model complexities. If you want to have the convenience of a mental picture of little particles whizzing around you have to accept that they behave very strangely sometimes. Because underneath that nice mental image of billiard balls bouncing around is a lot of hidden complexity.

grant hutchison
2017-Feb-05, 06:46 PM
So do these virtual particles travel at c, but they dont follow a null geodesic path out of the black hole?They don't have a path, really. As the quanta of a field, they turn up where they're "needed" to mediate the field's effects.
I think we have to keep separate the idea of real photons (light rays) and real gravitons (gravitational waves), as against virtual photons (electromagnetic fields) and virtual gravitons (gravitational fields). It seems to me that your other thread about light rays and gravity was getting those two mixed together rather indiscriminately, though I gave up reading it quite early on so it may have been clarified later.

Grant Hutchison

ishouldknowbetter
2017-Feb-08, 04:40 AM
They don't have a path, really. As the quanta of a field, they turn up where they're "needed" to mediate the field's effects.
I think we have to keep separate the idea of real photons (light rays) and real gravitons (gravitational waves), as against virtual photons (electromagnetic fields) and virtual gravitons (gravitational fields). It seems to me that your other thread about light rays and gravity was getting those two mixed together rather indiscriminately, though I gave up reading it quite early on so it may have been clarified later.

Grant Hutchison

Is this the same as saying their wave functions collapses where they're "needed"?