When Galaxies collide, supermassive black holes?

[BobbyJoeCool]

Tycho...

 

This is what you're saying indirectly...

 

Since the singularity is inside the black hole, you can't get any information from it, or about it. However, I know there there is a mass in the center of it (because of it's gravetational effects), and furthermore, I can tell you have much mass given only the diameter (which is twice the radius).

 

[math]v_{e}=\sqrt{\frac{2Gm}{r}}[/math]

 

Source

 

Where [math]v_{e}[/math] is the escape velocity at the event horizon (or the speed of light) G is the gravetational constant (apprx 6.67x10^-11, source also Wikipedia), m is the mass of the singularity, and r is the raduis of the event horizon.

 

[math]c=\sqrt{\frac{2Gm}{r}}[/math]

 

[math]c^2=\frac{2Gm}{r}[/math]

 

[math]rc^2=2Gm[/math]

 

[math]\frac{rc^2}{2G}=m[/math]

 

[math]m=\frac{rc^2}{2G}[/math]

 

r is given, c and G are constants...

 

but this is not possible because the information of the singulatiy cannot escape the black hole's gravitational well... but the ONLY information I know is it's mass. I do not know what it is (matter/anti-matter).

 

In the same way, if some mass falls past the EH, the ONLY information you will ever determine about it is it's mass. And your theorem says that you CAN determine mass... And this is all you know about the object that fell in. Therefore, you know it is there, but you do not know what it is, much like the singularity...

 

how about that? Does that answer you question?

[Martin]

Tycho and Bobby

http://chandra.harvard.edu/photo/2002/0192/BH_merge_sm.mov

 

computer animation showing two galaxies merging into one galaxy (the first 1/3 of the movie) which then contains two BH

so the movie zooms inside of the galaxy and you see the two BH circling each other

 

then the last 2/3 of the moving you see the two BH spiral in towards each other (because energy is radiated off as graviwaves, so the orbit cannot be stable)

 

and they coalesce inside one envelope

 

but the situation is still dynamic for a brief time and a huge amount of energy is still being radiated off as graviwaves

 

================

Tycho

 

No Hair applies to stable (not dynamic) BH solutions, for instance Schwarzschild. SO THE HAIRLESS ARE NOT RADIATING OFF ANY GRAVITY WAVES.

they just sit there. maybe they are charged, maybe the rotate, but they are essentially not changing and not losing energy by radiating waves.

 

but if you witness two BH coalescing, at that moment they have HAIR GALORE. mucho mucho hair. because as the singularities are falling towards each other (even inside the cloak of an horizon) a huge commotion of gravity waves is coming away (probably with all the information you could ever want about what is happening inside)

 

When you watch the animation you will see a lot of gravity waves coming away at the end. that is how the system can settle down quickly to a boring hairless BH-----it will not remain dynamic very long because of radiative damping of vibration.

 

the ringing of a BH has been described as so rapidly damped that it is more like the ringing of a MARSHMALLOW than the ringing of a bell.

[[Tycho?]]

Thats a neat simulation.

 

And I guess I must concede the point. I dont have any argument as to how gravitational information would be kept from escaping the event horizon, all I had was a feeling I guess that it seemed to violated that information dealy. Thanks Mart and Bobby for giving me some details on it.

[BobbyJoeCool]

'']Thats a neat simulation. Thanks Mart and Bobby for giving me some details on it.

 

Agreed, neet simulation.

 

And YW. I wish I could explain it better.