Black hole mass calculation,

[alpha2cen]

Let's think about this black hole calculation.

Black hole + mass1 = Black hole

Black hole + Black hole = Black hole

Above Black hole mass, mass measurement is meaningless?

[Mr Skeptic]

Any amount of mass you like can be a black hole, if you fit it into a small enough radius.

 

http://en.wikipedia.org/wiki/Schwarzschild_radius

[alpha2cen]

Then we don't use the black mass for calculation of the Universe or of galaxy mass?

[Spyman]

Do you understand the concept of Density ?

 

The Black Hole mass is NOT a max limit of mass, it is a ratio limit of mass per size.

 

A Black Hole that eats a body of a certain mass gets more massive by the same amount it swallows.

 

Black hole + mass1 = a Black hole that is mass1 bigger/heavier than before

Black hole + Black hole = a Black hole with twice the mass it had before

 

Different Black Holes have different mass and sizes just like stars and planets.

 

Why would the measurement of very massive objects be considered meaningless?

[alpha2cen]

How do we know the size and density?

Are the Black holes in the center of galaxy proportional to the galaxy size?

Are there any method to measure the mass or the density of the Black hole?

In my experience there are a few examples of Black holes except central Black hole in every galaxy.

[Spyman]

Despite its invisible interior, a black hole can be observed through its interaction with other matter. A black hole can be inferred by tracking the movement of a group of stars that orbit a region in space. Alternatively, when gas falls into a stellar black hole from a companion star, the gas spirals inward, heating to very high temperatures and emitting large amounts of radiation that can be detected from earthbound and Earth-orbiting telescopes.

http://en.wikipedia.org/wiki/Black_hole

 

It is now widely accepted that the center of every or at least nearly every galaxy contains a supermassive black hole. The close observational correlation between the mass of this hole and the velocity dispersion of the host galaxy's bulge, known as the M-sigma relation, strongly suggests a connection between the formation of the black hole and the galaxy itself.

http://en.wikipedia.org/wiki/Black_hole