Black Holes: Effects on Space Explored

[Joe_Limon]

Alright, so if a black hole warps space toward its center. Does this mean that as an observer approaches a black hole they would observe the universe around them expanding? Further, would that observer witness the universe behind them expand away from them, and when they reach the event horizon the universe would be expanding away from the observer at and then over the speed of light, thus making it impossible to escape the black hole?

Also, if gravity is dependent on the space between two masses, wouldn't the black hole effectively weigh many orders of magnitude less due to the warping of space? Effectively, the center of a black hole is much further than the far side of the black hole to an external observer.

Finally, if a black hole has a gravitational field proportional to what it should have given it's mass and ignoring spatial expansion. Then wouldn't that cause issues with the massed particle acting on massed particle view of gravity? Wouldn't it make more sense if gravity was a byproduct of the interaction between particles and how warped space becomes from massed particles?

 

[rootone]

They would see the rest of the Universe red shifting until it becomes no longer detectable.
I'm pretty sure of that much.

 

[bcrowell]

These are three different questions, but they all seem to be based on a misconception that gravity is an expansion of space. Gravity is curvature of spacetime.

 

[Joe_Limon]

What is the difference? Curved space is no longer linear space therefore portions of it have either expanded or collapsed. In the black hole scenario, mass is stretching toward the center. Stretching so much so that there is no direct path out of the hole.

 

[PeterDonis]

Does this mean that as an observer approaches a black hole they would observe the universe around them expanding?

No.

would that observer witness the universe behind them expand away from them, and when they reach the event horizon the universe would be expanding away from the observer at and then over the speed of light, thus making it impossible to escape the black hole?

No.

if gravity is dependent on the space between two masses

It isn't; at least, it isn't if this means what it appears to me to mean. But "dependent on the space between two masses" is pretty vague, so I can't be sure.

if a black hole has a gravitational field proportional to what it should have given it's mass and ignoring spatial expansion.

I'm not sure what this means either; a black hole's field is what it "should have been given its mass and ignoring spatial expansion", since the space (and spacetime, for that matter) around a black hole is not expanding.

 

[PeterDonis]

Curved space is no longer linear

I'm not sure what you mean by "linear". Curved space is curved, i.e., non-Euclidean.

therefore portions of it have either expanded or collapsed.

This does not follow. It's perfectly possible to have a curved space that does not change with time, so it isn't expanding or collapsing. The curved space around a black hole is such a curved space. (More precisely, the curved space that you get when you split up the spacetime around a black hole into space and time in a particular way.)

In the black hole scenario, mass is stretching toward the center. Stretching so much so that there is no direct path out of the hole.

This is not correct. As bcrowell said, your questions appear to be based on some misconceptions about what a black hole is and how it works. It might help in clearing them up if you would give some references for where you are getting these ideas; but in any case, the questions you're asking in this thread are based on misconceptions.

 

[PeterDonis]

I am closing this thread since the OP is based on misconceptions. Joe_Limon, if you have some references you are working from, PM me and I'll take a look at them.