# Black holes

1. ### juggalo2111

5
Do black holes become larger and larger with all the matter and light they consume? And is it possible for a black hole too merge with other black holes?

2. ### alexg

126
Yes, the radius of the EH increases with increased mass, and yes, black holes can merge.

3. ### juggalo2111

5
So is it possible for a black hole to consume all the matter and light in the universe and then merge together too create another big bang ?... Recreating everything as it was? Putting us in a never ending cycle of life and death? What do you think?

4. ### Identity

150
A black hole is just a collapsed star, so the gravitational field of a black hole is just like any star really. If we were a safe enough distance away from a black hole, Earth could orbit a black hole as if it were just another star. So to say that a black hole would consume all the matter and light in the universe is like saying any ordinary star could.

Also, we're living in a time in which the expansion of the universe is accelerating, so even if a black hole were travelling near the speed of light relative to us, it wouldn't be able to reach the furthest away galaxies.

5. ### phinds

9,148
"What do you think" suggests that you are asking for an opinion as though this were a subject about which so little is known that only opinions are possible. This suggests to me that you would find it very entertaining and informative to read some basic cosmology.

The FAQ thread in the cosmology forum here is a great place to start.

6. ### juggalo2111

5
Im not very confident with my own knowledge of Black Holes. Thats why i said "what do you think?". I have no idea what kind of knowledge we have gathered on this topic. Im not suggesting that our overall knowledge of Black Holes can only be answered with opinion. Thats why im on here trying too find out the facts. Thanks for suggesting the FAQ ill check it out.

Last edited: Feb 25, 2012
7. ### Chalnoth

5,484
Not likely. This would require the universe to stop expanding and recollapse in on itself. Right now the expansion of the universe is accelerating, and if this continues, in the far future most of the matter in our universe will continue moving apart forever.

8. ### nag555

5
Exactly...I too believe what u have told is exactly right....It may be true that universe is expanding and so the black-hole may not be able to influence its gravitational force through such long distances relatively. But the unanswered question is how long does the universe expand?

If one is to believe that universe has started from a big bang it means the energy of the universe should be equal to the energy that is released from the big bang which should be finite. In such an instance universe with such high energy intensity tries to reduce its energy intensity by expanding into outer space and coming in equilibrium with outer space. By its expansion it tries to reduce its energy density measured by the background cosmic microwave radiation presently about 2-3 K. Universe expands until its finite energy gets equally distributed such that temperature of the cosmic microwave background radiation = 0K. Once this expansion stops again universe starts contracting, black holes start merging and everything gets collapsed into one single point and again the big-bang happens. So it should by cyclic.

Presently acceleration of the universe doesn't mean the universe expands infinitely. Where do you expect the universe to generate the required energy to drive the acceleration of expansion of the universe forever(Energy cannot generate by itself). The present acceleration phase is fallowed by a deceleration phase like a damped sine wave where acceleration happens during the rise of the curve and deceleration happens during the fall of the sine wave. But ultimately the curve gets completely damped when its energy content is absolutely zero. Similarly the acceleration and deceleration phase all stops once the energy of the universe has been completely expanded into outerspace. You can verify this damping effect everywhere in nature. see how waves transfer its energy to sea shores. they are infact damping sine waves transferring the weight of the atmosphere to shores.

Last edited: Feb 27, 2012
9. ### Chalnoth

5,484
Given that the rate of expansion is now speeding up, chances are forever. The simplest models of the universe do this. It takes some very convoluted models to have our universe recollapse back in on itself in the distant future.

This isn't true. Energy is not conserved in an expanding universe. Early-on, during inflation, the amount of energy increased by somewhere around $10^{80}$ or so. For much of the history of the universe since inflation ended that amount of energy has since been decreasing. More recently it has started to increase again.

10. ### nag555

5
. Such a statement is too stubborn. You should be open minded before evaluating any such statements. You give me 100 references to prove your hypothesis. I give you another 100 references to prove that's not correct. A highly debatable topic. Not Einstein or not even Noether decides if energy is conserved in time translations or various frames of references. It should be your gut feeling that ultimately answers. Tomorrow some other comes and says i found something that travels faster than light or could go below 0K which might be true. How can we just support all these theories based on baseless assumptions.

11. ### phinds

9,148
Uh ... dude, this is a SCIENCE forum.

12. ### Nabeshin

2,200
This post shows a complete misunderstanding of modern cosmology.

Calnoth is correct, generally energy isn't really conserved in any meaningful sense in General Relativity (because it is impossible to consistently define anything like an energy that will be conserved on global scales). This has been known for about a hundred years, since Einstein wrote down his theory. See: http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html

13. ### juggalo2111

5
Did the big bang create space? Or was that already there? Does the universe have an end point? If so Does the universe have an end point in which the gravity is so strong nothing could escape??? Creating a rebound affect and driving everything back too the center? Too recreate another big bang??

Last edited: Feb 27, 2012
14. ### phinds

9,148
You would do well to read some basic cosmology. The FAQ in the cosmology section is a good place to start

15. ### Chalnoth

5,484
Huh? No. It's simple fact. This is the way the universe is. Deal with it. Others have provided some good reading materials to this effect.

16. ### Deuterium2H

59
The hallowed principle of Conservation of Energy, which seems so inviolable in all other aspects of Physics, simply has no traction when it comes to modern Cosmology, and the measured fact of an expanding Universe. As I have stated in other threads, the simplest answer is to simply do away with it altogether, and reconcile onself to the proposition that Energy is NOT conserved in an expanding Universe.

5