Finite Black Holes? Answers for Xap's Question

[Xaphan]

please forgive my ignorance but, i was watching somthing in tv the other day about supermasive black holes, now my question is, if some black holes are more massive than others, how can their mass be infinite? if Blackhole A is more massive than black hole B then surly they can't both be infinite in mass.

been reading the fourm for months and never posted basicly because i leave it to the people who know what they are talking about and I am sure you guys will put me straight

thanks, Xap

 

[mathman]

Black holes do not have infinite mass! Could you explain where you got this idea.

 

[Xaphan]

i was under the impression that a black hole is a singualrity and thus "infinite" in mass
but I am getting the idea I am very wrong

 

[SystemTheory]

This Black Holes FAQ appears to be accurate and will answer your basic questions:

http://cosmology.berkeley.edu/Education/BHfaq.html#q5

There is a theory of black holes on a quantum scale that might be tested with the newest and biggest particle colliders. So they can be tiny. To me, the singularity means the laws of math break down, but I'm not sure what becomes infinite in the actual equations. Apparently it is not the mass.

I would add that it is the density of mass in a small volume which defines a "black hole." The curvature of space-time does not allow light (EM waves) to escape inside a radius known as the event horizon. The FAQ either describes or implies this interpretation.

 

[mathman]

According to some theories, the black hole mass has shrunk to a point (the singularity) and therefore the mass DENSITY is infinite. Current physics has this as an open question.

 

[cesiumfrog]

According to some theories

You make GR sound so unrespectable.

 

[Hurkyl]

i was under the impression that a black hole is a singualrity and thus "infinite" in mass
but I am getting the idea I am very wrong

A singularity is just a place where things stop behaving nicely. It's derived from the word "singular", meaning something like "being out of the ordinary" or "departing from general usage or expectation".

In this case, it signifies the fact that if we don't put a hole in our mathematical representation of space-time, then there will be one or more points inside that are mathematically obnoxious.

 

[mathman]

You make GR sound so unrespectable.

GR and quantum theory are both very accurate in their respective regimes. However, inside a black hole when they are needed together, the theory breaks down, particularly when describing the singularity.