Originally Posted By: Bill S.
My only reluctance is that I like to think I understand a point, as well as possible, before moving on to the next. So I need to be able to answer questions like: Can we measure gravity at an event horizon of a stellar BH? If so, how would that compare with gravity at the surface of the original star?

The problem is you have only half the GR theory worked so far.
Your half creates a blackhole immediately any gravity forms, so I can't answer what will happen.

You have a curvature in spacetime in the presence of energy/matter but something has to invert time back to what it was originally. You can make it whatever you like space is elastic, there is a back pressure, the green alien inverts it back but something has to as you have spacetime as passive currently ... see the issue smile

The problem is obvious if time wasn't restored back there would be this big time curvature tracks carved across space where planets/suns moved thru. It would be like a boat moving thru water and the water not levelling the wake left behind it.

I guess you could go for there is no time in space and things with gravity tow time around with them?
So time would be like electric charge under that scheme I guess intrinsic to matter/energy and space is passive.

Both space and time being passive gives huge issues I need a solution from you smile

Originally Posted By: Bill S.
As far as the idea of gravity creating gravity goes, I had reached the point of thinking “does gravity create more gravity? That raised a few questions, like:

Wouldn’t it have to have mass/energy to create more gravity

Energy and it does remember its covered here
https://en.wikipedia.org/wiki/Vacuum_solution_%28general_relativity%29

Originally Posted By: Vacuum GR solution
But the gravitational field can do work, so we must expect the gravitational field itself to possess energy, and it does.


Originally Posted By: Bill S.
If it’s not a force, can it have energy?

Well radiation has energy is it a force?

See this is where it gets tricky for me I need you to define force are talking classic physics/QM/your own?

Originally Posted By: Bill S.
Manifestly, gravity is not a run-away phenomenon. Is that because something counters it, or because gravity does not spontaneously create gravity. Which is it?

How can you get a black hole if it doesn't go into runaway, that is like having an atomic bomb without critical mass ... think about it laugh

History lesson
http://www.physicsoftheuniverse.com/scientists_schwarzschild.html
Quote:
Schwarzschild’s solution identified a radius for any given mass, known as the Schwarzschild radius, where, if that mass could be compressed to fit within that radius, no known force or degeneracy pressure could stop it from continuing to collapse into a gravitational singularity or black hole.

You don't have any back pressure so any gravity at all will collapse into a black hole as it has to overcome ZERO smile

As I said I am open for anything you believe lets just see where it goes smile

Originally Posted By: Bill S.
What physical/experimental evidence do we have for saying that gravity creates gravity?

Einstein and scientists did some tests on a 1919 solar eclipse for a reason to check the curvature of light from the sun smile

Here is the problem in it's conceptual form
https://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity

So you end up with gravity as a radiation although it is still unclear to me if you want to treat it as a force or not.

Last edited by Orac; 07/27/15 07:36 AM.

I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.