quote:
Originally posted by Time
quote:
Originally posted by CookieRevised
Since the singularity has a mass it can be considered an object; a quantum mechanical object.
No, it has infinte mass - beyond an object. Even the laws of quantum mechanics break down.
Revise the theories and their formulas which describe black holes and stuff related and which are used to calculate stuff concearning black holes. They all include
M the mass of black hole. If it was infinite not a single formula concearning black holes would compute.
Black holes can have any mass, from the very small to extremely large.
Even the Schwarzschild radius,
R, is calculated using
M
R = 2*G*M/(c^2)
G = Newton's gravitational constant
M = Mass of the object
c = speed of light
If
M would be infinite it would mean we don't even exist! Because if the mass of only 1 single black hole in the universe is infinite, it would mean we are inside its Schwarzschild radius aka inner event horizon, in other words we all would be dead!
Take "Cygnus X-1", this is a powerful x-ray source and it is calculated that it must be much much smaller than 1/100th of a light-second across, aka smaller than the size of the Earth. And because it also forms a binary with a blue supergiant "HDE 226868" whose mass is +-30 solar masses, they calculated that the source (a black hole) is about 7 solar masses, aka a very small black hole!
quote:
Originally posted by Time
quote:
Originally posted by CookieRevised
quote:
Originally posted by Time
They showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole.
Yes and no.
Hence, "sufficiently massive". The limit above which they do is called the Oppenheimer-Volkoff limit.
Yes, but only for neutron stars. And the upper limit for the mass which a star can have is:
- for white dwarfs (Chandrasekhar mass limit): 1.4 solar masses (above that and they will explode into a nova, aka super nova type 1 (see previous post).
- for neutron stars (Oppenheimer-Volkoff mass limit): +-2 to 3 solar masses, but generally stays well below 4 or 5 solar masses. Again see previous post.
This means any neutron star which has a mass below 4-5 solar masses will turn into a pulsar and above 4-5 solar masses will collaps into a black hole. In other words, again, the mass of a black hole can vary greatly and is not infinite at all...
Also note that this mass limit only goes for the current mass of the star aka the mass of the white dwarf or neutron star, not for the initial mass of the star before it imploded; A star can start of as a 9x solar mass star and still end up as a stable red dwarf of 0.5 solar masses.
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