# Black Holes and Big Bangs

1. Feb 27, 2006

### Epircus

Ok so awhile back I was thinking about Black Holes, and I've started to wonder the possiblity if Black Holes are like universal recycling bins?

(Please note my physics knowledge is not that of some one of a degree I'm only taking what I've learned from books I've read)

A lot of people like to argue that the second law of thermodynamics shows us the universe cant be 20 billion years old...because the universe Would Have reached a state of entropy. Now lets take newtons laws and we know that energy can't be destroyed. We also know(the most obvious) e=mc2.

So what I'm getting to is when a black hole engulfs a star does it stop there? It doesnt. A black hole becomes more massive with each object it takes in. Making it even denser each time..We can look at the center of our own galaxy and see theres a massive black hole. Theres also black holes in the center of other galaxies, eventually the black hole will consume our galaxy, But what next will the black hole stop at our own galaxy(sadly i lack the mathmatical skills to calculate a black holes desnsity) It would be extremely dense and start to pull in other galaxies. All that energy going in the black hole has to go some where..and space has to have its own limits(right?) So when space can no longer hold the amount of energy a black hole has...Im predicting that once a black hole becomes so massive it will not be able to support itself no longer and explode...the explosion of course would spread matter all out again recycling energy creating new universes...the explosion would obviously be a big bang.

once again...if im entirely wrong with my information please post it...i know theres really no way to prove this...but I find it fun to think about.

2. Feb 27, 2006

### chroot

Staff Emeritus
Welcome to PF!

Note that a black hole of mass M does not "suck in" other galaxies more than any other kind of object with the same mass M. They're not like cosmic vacuum cleaners. To the world outside the black hole, the black hole is gravitationally just like any other similar mass.

Also, a black hole's "density" is a poorly-defined concept. If indeed there's a singularity at the center of a black hole, then every black hole of any mass contains a singularity of infinite density.

Your conception of "space no longer able to hold the energy" is honestly rather non-sensical. Space does not "hold energy." There's also no reason that super-massive black holes will spontaneously explode.

One conception of the so-called "heat death" of the universe is that all matter will eventually wind up in a black hole. Black holes evaporate over time, producing mostly radiation. The universe will end up essentially filled with light, all its matter having been converted into light by black hole evaporation.

- Warren

3. Nov 26, 2006

### michaeln_2006

I am just a new college student who knows little about physics as well.. but I was sitting the other day just thinking about things, and I came up with the same idea. The same exact idea actually! Black holes will eventually suck up everything, then they should all come together and make one big black hole then there will be nothing left anywhere except the black hole and everything within it. And if black holes do have singularities, then everything in the universe will exhist in a tiny dot just like in the big bang theory. I know I'm not using scientific terms and I may have even spelled some things wrong, forgive me I'm tired and it's late...

Maybe there is no begining and there is no end, maybe everything has allways exhist and always will. Everything just recycles in this never ending black hole big bang cycle. It's hard for my mind to grasp that becuase I have always been tought that God was the begining and the end, but if this is true..Where did GOD come from? Maybe I'm just rambling on and not making sense, sorry this is how my mind thinks. Random and crazy! :)

4. Nov 26, 2006

Staff Emeritus
Well the black holes are now thought to evaporate very slowly through Hawking Radiation.

I am not going though one more description of that to a newbie, but there is plenty of stuff at different levels on this very forum, not to speak of wikipedia and google, that the mere words in a search should get you to an exposition you can work with.

At any rate this adds a third act to your sucking up picture. After the black holes suck everything up, they slowly evaporate until there is nothing left but empty space with a few low energy photons flying around. And that's the current view of most of the physics/astronomy community.

5. Nov 26, 2006

### Ironman Joe

Hawking says that Black Holes release bits of themselves. Not even light, 186,000miles per second can escape the gravity of a black hole. Einstien says that nothing can excede the speed of light. One of them must be wrong.... Energy can neither be created nor destroyed, only changed in form. When energy strikes the event horizon of a black hole, does it add energy to the singularity, or mass to the black hole, or both???? too many people think of gravitational fields, the same way they view magnetic fields, with curved lines of force, a north and south pole. Gavitational force flows in straight lines out from the center in all directions. Moons and planets do not orbit according to magnetic fields, they orbit according to gravitational force, around the center. If planet A is being held by planer Bs' gravity, and planet B ceases to exist, how long before planet Bs' gravity no longer affects planet A. Instantly? Or does it take time, because nothing can excede the speed of light??

6. Nov 26, 2006

Staff Emeritus

Nope, you have failed to understand the basic idea of Hawking Radiation, and your whole exposistion is wrong. I repeat, google, wiki, search this forum, and try to understand what you find.

7. Nov 26, 2006

### Ironman Joe

PF, I could go to google, or wiki, or every formula, and equation laid out before me in every mystifying detail, and still not have a clue. I am a layman, if you haven't already figured that out, who needs things explained in laymens terms. A scientist on TV stated , in simplistic terms, that a black hole would "Flick off bits of itself into space". These bits would have to come from the surface of the black hole, below the event horizon. What kind of force is required to accelerate these bits to an escape velocity that would have to be FASTER than light? I do understand that by "bits" he did not mean pieces, or chunks, etc. He meant tron, or on sized bits, (electrons, photons etc.) If this is indeed the case, then those trons, and ons when they hit the surface of the black hole remained in tact. If they splattered on impact, and were turned into quarks, how did they get back together to be "flicked off"? Face it, what happens beyond the event horizon, nobody really has a clue. It's all just guess work. If the laws of physics do not apply beyond the event horizon, what laws do?

8. Nov 27, 2006

### George Jones

Staff Emeritus
Quantum field theory is involved, so you should read some popular expositions of quantum field theory.

Steve Carlip has written an exposition of Hawking radiation in terms of quantum processes, to which I gave a link in a https://www.physicsforums.com/showpost.php?p=620350&postcount=4".

Last edited by a moderator: Apr 22, 2017
9. Nov 27, 2006

### QuantumCrash

Hawking radiation is caused when particle-antiparticle pairs simply appearing near the event horizon of a black hole. Nothing can escape a black hole when it is inside the black hole but the instability around the event horizon creates what Ive just said, and if you are moving near the speed of light away from the black hole just outside the event horizon, you CAN escape.

10. Nov 28, 2006

### Ironman Joe

"Nothing can escape a black hole" The Hawking Radiation of which you speak occurs OUTSIDE the event horizon, not from the black hole. If nothing can escape a black hole, then how can it possibly evaporate?

11. Nov 28, 2006

### Labguy

Re-read post #8 above and then go to the link(s) provided. That explains it about as well as any you'll find.

12. Nov 28, 2006

### Ironman Joe

OK, Let us use Hydrogen as the "pair". The negatively charged electron crosses the event horizon. It encounters a gravitational force capable of accelerating it to the speed of light instantly. The bond between it and its' positively charged partner is broken, also instantly. With its' bond to its' negatively charged partner gone, it shoots off into space. The black hole has lost nothing, in fact it has gained the mass of an electron.

13. Nov 28, 2006

### Labguy

That's just not how it works, but trust me, there have been PLENTY of PF threads on the subject. All you need is to find a few and read for hours.

P.S. Electrons or any particle with mass will never accelerate to c.

14. Nov 28, 2006

### Ironman Joe

Yes, I know that nothing can exceed C, relative to its' point of origin. Nothing can break the gravitational hold of a black hole. Nothing of course except Hawking Radiation. If a black hole is, in fact, what science thinks it is, then Hawking is wrong. If Hawking is correct in his theory, then everybody else is wrong, and a black hole is not what we think it is at all. But then the only thing we really know about balck holes is that they suck really hard .

15. Nov 28, 2006

### Labguy

Are you still refusing to pay attention to post #8 above? Too lazy to read a bit? As someone once said:

16. Nov 29, 2006

### SpaceTiger

Staff Emeritus
I think the original issue has been addressed. Let's move on.