blackholes

[shadow2121]

I read that inside a blackhole time stops. So wouldn't that mean that gravity would stop since time has to stop for something to fall? Also, when you enter a blackhole wouldn't you simply freeze?

[frosch45]

I could be 200% wrong on this, but I thought that a black hole was a star with such intense gravity that it pulls the light (photons) that it would be emitting back to its surface.... and as such, it being a star, it would still be emitting infared radiation (heat) which since it is not matter, it would still be able to radiate heat, and it is a star, so it would emit the heat....

 

I could be very very wrong on that, but....

 

From wiki

 

A black hole is a region of space in which the gravitational field is so powerful that nothing, not even light, can escape its pull after having fallen past its event horizon. The term "Black Hole" comes from the fact that, at a certain point, even electromagnetic radiation (e.g. visible light) is unable to break away from the attraction of these massive objects. This renders the hole's interior invisible or, rather, black like the appearance of space itself.

[/Quote]

 

maybe i'm just misunderstanding it...

[Kyrisch]

I read that inside a blackhole time stops. So wouldn't that mean that gravity would stop since time has to stop for something to fall? Also, when you enter a blackhole wouldn't you simply freeze?

 

Gravitational fields cause time dilation. Since the field within the event horizon is so strong, an object entering a black hole would appear to slow down to a standstill from an observer outside its gravitational influence. Time never 'does' anything, the effects of time dilation are just due to differences in reference frames.

[honestdude14]

I could be 200% wrong on this, but I thought that a black hole was a star with such intense gravity that it pulls the light (photons) that it would be emitting back to its surface.... and as such, it being a star, it would still be emitting infared radiation (heat) which since it is not matter, it would still be able to radiate heat, and it is a star, so it would emit the heat....

 

I could be very very wrong on that, but....

 

From wiki

 

 

 

maybe i'm just misunderstanding it...

I agree with frosch. The way I understand it.. if you even got close, the gravitational pull would be stong enough to collapse even the strongest of matter.

[Mr Skeptic]

A black hole is a body so massive that the known laws of physics break down (or they might not, but then you have a singularity). One effect is that time slows to a stop as you approach the event horizon. Whether it actually stops or not, I don't know. Stopping time would certainly mess with physics as we know it. Anyhow, whatever happens inside the event horizon is pure speculation, as we are never going to be able to test anything.

[ajb]

Time does not stop once you pass through the horizon. Forgetting the great tidal effects, you will not notice anything. (Or at least till you hit the singularity? But as mathematical relativists we cut the singularity out for now )

 

What is true is that due to time dilation, as see from a distant observer you never reach the horizon. You get more and more red shifted and you get more and more fainter.

[Arch2008]

http://www.amnh.org/learn/pd/physical_science/week3/time_dilation.html

t(rocket) = t(Earth) √[1 - (v/c)2]

In this equation, time on the rocket moving near the speed of light c is equal to time for an observer (in this instance on Earth) times the square root of 1 minus the square of the ship’s velocity divided by c. Mmmmkay?

If the ship’s velocity is c (like inside a black hole), then the value on the right becomes zero. Therefore, an infinite amount of time for an outside observer would pass before one second passed for the observer on the ship traveling at c. However, time still passes for the observer traveling at c. The universe would grow old and all the protons would evaporate and then time for this observer inside the black hole would continue.

[Klaynos]

But here we're talking about a gravitational time dilation are we not?

[Arch2008]

There's no difference. The effect of traveling at c remains the same. Unless you see something that I don't.

[Edtharan]

I could be 200% wrong on this, but I thought that a black hole was a star with such intense gravity that it pulls the light (photons) that it would be emitting back to its surface.... and as such, it being a star, it would still be emitting infared radiation (heat) which since it is not matter, it would still be able to radiate heat, and it is a star, so it would emit the heat....

Infra-red radiation is still photons , so it wouldn't even emit heat.

 

I read that inside a blackhole time stops. So wouldn't that mean that gravity would stop since time has to stop for something to fall? Also, when you enter a blackhole wouldn't you simply freeze?

It depends on your frame of reference (frames of reference are an integral part of Relativity, which black holes are a consequence).

 

From the frame of reference of an outside observer (many light years away), then the person/object falling into the black hole will appear to slow down and never enter the black hole.

 

However, from the frame of reference of the observer that is falling into the black hole, they don't see themselves slow down but they do see the rest of the universe speed up. So they will eventually cross the event horizon (there will be nothing physical that will mark the Event Horizon, but they will be able to determine that they have crossed where it should be based on the positions of matter outside the black hole).

 

This is really strange stuff. From one point of view, the person never enters the black hole, but from the other point of view they do. How can one enter a black hole and also not enter it?

 

Actually, the outside observe sees the person take an eternity to enter the black hole, but the person falling in sees an eternity occur out side the black hole as they fall in.