Do neutron stars/black holes change size?

Question

Did the supermassive black hole at the center of our galaxy expand as the material around it was consumed, or did it start out the size it is today?

Answer 1

The event horizon grows larger - the singularity - if there is one remains as tiny as a true mathematical point.

Give 'a brief history of time' a go to read more about black holes. I feel black holes as they are currently theorised do not exist as they don't fully comply with quantum mechanics. Look up gravastars to see about one alternative idea for what they might be.

Answer 2

A star is ballanced by two opposing forces: gravity, which pulls matter in (therefore the "weight" of the mass compresses the center) and some force that tries to pull the matter appart. In an ordinary star, the head resulting from nuclear reactions in the innermost layers tries to expand the gas that constitutes the star, the same way a hot air baloon inflates when you heat up the air inside it. The pressure from the free electrons inside the star is what keeps the star from collapsing; the phenomenon is called "electron degeneracy" and it comes from the Pauli exclusion principle, which says that any given energy state of system can only have zero or one fermions (which are particles which have semi-integer spin, for example 1/2) such as an electron. This makes the electrons occupy an imense number of different energy levels inside the star, and the highest energy contribute the most to keep the pressure high. (Pressure is a macroscopic manifestation of particles exerting force randomly on their vicinity.) In a neutron star, the gravity has compressed the matter so much that it has forced nuclear reactions in another direction, namely pushing the electrons against the gas protons and creating neutrons. The neutrons are also fermions, because they have spin 1/2. These are more massive, therefore they have "more energy", so because they are in about the same number as electrons (electron + proton -> neutron) they take their place at maintaining a degeneracy pressure to sustain the star. A black hole is simply an region of space where the escape velocity is greater than the speed of light. You can have particles escaping the OUTER vicinity of a black hole, provided their speed is big enough (closer to c as you approach the black hole's event horizon). When you're exactly over the event horizon, the escape velocity is exactly c. A luminal particle exactly over the even horizon will not fall back into the black hole, but it won't escape either. If you study calculus in high school or college, you might get familiarized with the mathematical concept of "limit", therefore names such as "limit" and "boundary" and "open boundary" and "closed boundary" will become familiar, and these are important to ellucidate on the maths supporting these phenomena. A black hole does not have an "escape velocity" in the same sense that Earth does not have an "escape velocity". It depends on your distance from the object -- more precisely, from the gravitational field. For Earth, its escape velocity is defined AT IS SURFACE; if the Earth had a different size, you'd have a different escape velocity because it is defined as the "velocity necessary to escape a gravity field starting from a certain distance from the field source". For a black hole, the event horizon is the locus where the escape velocity becomes exactly c. The locus where the escape velocity is greater than c is "inside" the black hole; the locus where the escape velocity is less than c is "outside" the black hole.

Answer 3

A neutron star is a collapsed 2 to 3 solar mass white dwarf,maybe 100 km in diameter
As it accretes matter from it's surroundings the gravity increases[with a small diameter increase] and it collapses into a neutron star,about 12 km diameter.
The neutron star has a small increase in diameter,the gravity increases.
The internal space of a neutron star is maintained by degenerate neutron pressure.
If this pressure is over come by gravity the remaining internal space is displace,it's diameter drops to 6 km.
All the neutron in the star are in contact with each other,it cannot collapse any farther without destroying all the neutrons.
A black hole of the same mass would have to be about 3 km in diameter.
This 3 km space between the collapsed neutron star and the
black hole[not the actual space] the virtual black hole would be inside the neutron star, since no space exists for the neutron star to collapse farther,and the only way a black hole can exist is from a collapsing neutron star,I can't see how a black hole can exist.

Answer 4

No black hole started as a supermassive black hole, they expand as they consume nearby material, from any source, that happens to be attracted by its gravitational force.
There are examples of binary star systems where one of the stars is actually a black hole and is literally sucking slowly material from its companion.

Answer 5

A neutron star can absorb enough matter to increase its escape velocity to 299,792,458 metres/second, at which point it becomes a collapsar (some people are still using the misnomer "black hole", unfortunately, but a black hole requires an event horizon, and many scientists are of the opinion that such a thing does not exist, like Prof. Stephen Hawking, who wrote the bestseller "A brief history of time.", and who has long ago changed his mind concerning them. For an explanation, go to the blog of Jack. Norton-Krell, at www.myspace.com [archived], or see the various viewpoints at the Wikipedia website). They increase both in size and mass. It was much smaller at one stage.

Answer 6

i dont think our black hole is super massive.... i could be wrong.

also, to become a black hole, it had to be something like a star that was a perfect size, and collapsed.. if its not the perfect size it turns into something else... i forget what though.

i think its mass grows, but not a measurable amount considering that even after gobbling stars and planets its still smaller than a marble.

Answer 7

what