At the center of a black hole is it the same time as the moment of its formation?

[Ben Kenobi]

No, I mean into the event horizon. Solve for a radial plunge to Schwarzchild limit. You get infinite time for any reasonable outside observer.

Did you even get to GR, dude?

Then it's already been explained, and correctly so. From the frame of reference of the object falling into the black hole, it simply accelerates up to the event horizon, and then falls in.

[KrazyHorse]

Originally posted by Ben Kenobi


Why?

Space isn't warped until the singularity forms. The only reason it takes an infinite amount of time is because of how the gravity warps the space around the singularity to the limit of infinity.

Dude. Work through the ****ing math yourself. It's easy enough. To make it easy you can treat the inflow of material as a pressureless gas.

[Jon Miller]

He was thinking about getting a job elsewhere, the last time he posted here. I don't remember what came of that.

JM
(One of the possibilities was MD, I am pretty sure that he didn't take that possibility.)

[KrazyHorse]

Originally posted by Ben Kenobi


Then it's already been explained, and correctly so. From the frame of reference of the object falling into the black hole, it simply accelerates up to the event horizon, and then falls in.

Are you retarded? The question has to do with how it looks like to an outside observer.

[KrazyHorse]

Originally posted by Ben Kenobi


Why?

Space isn't warped until the singularity forms. The only reason it takes an infinite amount of time is because of how the gravity warps the space around the singularity to the limit of infinity.

This is patently untrue. There is no need for an infinite gravitational field for there to be divergences in observer time versus proper time.

[Ben Kenobi]

Why are you bringing stars into it?

The point is that for anything to actually enter the Schwarzchild radius takes an infinite amount of time. Doesn't matter what the mechanism is.

Prior to the formation of the black hole, what's the schwartzchild radius?

Dude, this is an entire different problem. You are asking what happens when a star collapses to form a black hole, not what happens when the hole is already there.

[KrazyHorse]

Originally posted by Jon Miller
He was thinking about getting a job elsewhere, the last time he posted here. I don't remember what came of that.

JM
(one of the possibilities was MD)

I'm really beginning to feel like it was him...

[KrazyHorse]

Originally posted by Ben Kenobi


Prior to the formation of the black hole, what's the schwartzchild radius?

Dude, this is an entire different problem. You are asking what happens when a star collapses to form a black hole, not what happens when the hole is already there.

OMFG. Oh my ****ing God. Do you think that GR effects just appear all of a sudden?

Dude, seriously: have you even taken a GR class?

[Ben Kenobi]

This is patently untrue. There is no need for an infinite gravitational field for there to be divergences in observer time versus proper time.

True, we see enough wierdness already around massive stars.

However, for it to reach infinity, as we see around the event horizon, we would need a singularity already there.

Ok, try this. why don't you solve for an event horizon without the singularity? Same mass, but not compressed to an infinite point, just very, very small.

What happens to an object as it falls towards this extremely dense, massive object? It would appear to slow down, just as it would in the event horizon, but eventually we would see a collision.

[Ben Kenobi]

OMFG. Oh my ****ing God. Do you think that GR effects just appear all of a sudden?

Dude, seriously: have you even taken a GR class?

No, where did I say that.

You are saying there is a 'paradox' when the reality is that there isn't a paradox at all. From the frame of reference of the outside observer, the formation of a black hole isn't anything special, since for the time dilation to reach an infinite period of time requires a singularity to exist.

You can't have the chicken without the egg.

Yes, time dilation would be there, but it doesn't reach infinity until there is a singularity. I'm beginning to think you don't understand a thing about stellar collapse and formation.

[KrazyHorse]

Ben I'm seriously not going to sit here and argue in words what I can prove in a half page of calculations.

For a non-rotating body the rate of mass accretion (measured by an outside observer) for any sphere of radius R drops to zero as the mass in the sphere approaches an amount sufficient to create an event horizon.

[KrazyHorse]

You are also throwing the word "singularity" around a lot. I suspect you are unaware of the difference between a coordinate singularity (as exists at the event horizon) and a mass singularity. You do not need a mass singularity to create a coordinate signularity.

[snoopy369]

Originally posted by Ben Kenobi


No, where did I say that.

You are saying there is a 'paradox' when the reality is that there isn't a paradox at all. From the frame of reference of the outside observer, the formation of a black hole isn't anything special, since for the time dilation to reach an infinite period of time requires a singularity to exist.

You can't have the chicken without the egg.

Yes, time dilation would be there, but it doesn't reach infinity until there is a singularity. I'm beginning to think you don't understand a thing about stellar collapse and formation.

Ben - when'd you get your Ph.D.? It obviously took an impressively short amount of time ...

[Kuciwalker]

Originally posted by snoopy369


Ben - when'd you get your Ph.D.? It obviously took an impressively short amount of time ...

Uhh, I'm pretty sure Ben didn't even finish his BSc. At least not in physics. (Didn't you end up getting a degree in history?)

[snoopy369]

That was the idea