Animating Black holes and Singularities - Comments

[edguy99]

edguy99 submitted a new PF Insights post

https://www.physicsforums.com/insights/animating-black-holes-singularities-infinite-force-gravity/

https://www.physicsforums.com/insights/wp-content/uploads/2015/05/graviytanimation-80x80.png

https://www.physicsforums.com/insights/animating-black-holes-singularities-infinite-force-gravity/

 

[phinds]

I don't know if you meant your statements about elastic collisions and inelastic collisions to be just special cases that you are using or if you think that they are correct general definitions, but just to be clear, as general definitions, your statements are both wrong so if you intend them to be a special case, you should probably edit to state that.

 

[Pacifique]

is the black hole really exist?

 

[wabbit]

Sorry if you covered this in a previous post which I missed, but I am a little confused about the nature of these animations : are they simulating an approximation of GR, or a different system which displays qualitative analogies with GR ?
Either is interesting, but i would be helpful if you could clarify this point, and if it is an approximation of GR, maybe explain a bit more about how your equations relate to those of GR or where the approximation is expected to be valid.
Thanks

 

[edguy99]

is the black hole really exist?

You bet they do. We see stuff fall into them and we can detect their gravity pull on other objects.

 

[edguy99]

In response to the question by wabbit, "are they simulating an approximation of GR, or an analogy with GR?"

Good question, I would say a combination.

WRT use of the distance cubed factor to produce precession, this is an approximation. But it sure works well, enabling orbits with a precession rate as fast as their orbit rate. It is required to give the animation the curve into the center. If you don't use the cubed factor, you end up with an ellipse. As to how it relates to GR, I am guessing an accurate GR equation would have a cubed factor, maybe a forth and so on, each of which would have a smaller effect.

WRT to inertia between emitting and absorbing bodies, this to me is a qualitative analogy with GR.