that theory is not popular because we are moving farther away from the "center" at a faster and faster rate.

As to what it is, people are uncertain. But it is a super mass of gravity to which nothing escapes. don't think of it as a hole, think about it as a point where gravity pulls with incredible strength and a magnetic catastrophe. Although I am no astro-physicist

But the accelerating expansion pretty much defies normal physics anyway... why does it preclude the existence of a super-massive BH at the center of the Universe?

This post was edited by Aliengames on Jun 7 2010 08:58pm

wait a min!! anythin which has a finite mass is bound to have a finite density, holy!! i just realised tht size, mass and density are neither directly nor indirectly proportional but yet they r related to each other!! if u know wht i mean...
for example: if u take a sphere/ a ball kinda thing of mass 100 kg, size 1meter diameter , density say 100 per sq. cm. i am not good at units so bare with me here. i mean what is density after all the number of particles per unit area rite!
so as long as the mass/size is finite density cant be infinite
if the density is infinite the mass is definitely gonna be infinite no matter what size it is
n we all know size of black hole is like the size of an atom so its definitely not infinite n the mass of a black hole we dun know its huge!! so density tends to be quite a huge number may be even 10^100 but still its a number, not infinite

This post was edited by xpeliama on Jun 8 2010 08:37am

black holes do not occupy space. its not "the size of an atom" or "infinitesimally small" it simply just doesn't occupy volume
its a finite mass in 0 volume. infinite density

nvm

This post was edited by Aliengames on Jun 9 2010 04:39pm

good point. i still havent seen any proof ie gravitational lensing etc... i do like the idea of the "big crunch"

This post was edited by juliusjuice on Jun 9 2010 06:02pm

A black hole, according to the general theory of relativity, is a region of space from which nothing, including light, can escape. It is the result of the deformation of spacetime caused by a very compact mass. Around a black hole there is an undetectable surface which marks the point of no return, called an event horizon. It is called "black" because it absorbs all the light that hits it, reflecting nothing, just like a perfect black body in thermodynamics.] Under the theory of quantum mechanics, black holes possess a temperature and emit Hawking radiation, but for black holes of stellar mass or larger this temperature is much lower than that of the cosmic background radiation.

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.

Astronomers have identified numerous stellar black hole candidates, and have also found evidence of supermassive black holes at the center of galaxies. In 1998, astronomers found compelling evidence that a supermassive black hole of more than 2 million solar masses is located near the Sagittarius A* region in the center of the Milky Way galaxy, and more recent results using additional data find evidence that the supermassive black hole is more than 4 million solar masses.

scientists have never directly observed a black hole and therefore have no proof that they actually exsist, just strong evidence that they do exsist and some mathematical theories to back that up, but the way i think of it is just like a normal star like a pulsar except that it got so small and dense that instead of being the brightest in the sky it pulls its own light back in on itself



isnt it obvious that black holes dont have zero volume and infinite density, becuase if they did they would all have infinite gravity, but blackholes are different sizes, and yes it may be extremely close to zero volume and infinite density, its like the graph of 1/x
the line never touches zero, but it gets infinitely close, just like a black hole would get infinitely close to zero volume, but never could, becuase if it did it wouldnt exsist in our universe anymore



This post was edited by elitepie on Aug 3 2010 09:49pm

From what I remember, they are formed when a star dies/explodes or something
I watched a lot of stuff on history/science channel but it's hard to grasp/remember/explain