Why hasn't the whole universe been sucked into black hole?

Question

If the singularity of a black hole can absorb infinite mass and energy, what is stopping one from just devouring the entire universe? If nothing can escape and nothing can stop them, shouldn't they be like the drains in a filled bathtub with us on the surface of the water?

Answer 1

This was something that I misunderstood about black holes for a long time as well. Yes, there is a point of no return where nothing can escape a black hole. This point is known as the event horizon. At this point, space becomes so curved that nothing can escape, but outside of this distance from the black hole, space is normal.

At any significant distance from the black hole, it would exhibit the same gravity as the star did before it became a black hole. It's just that the black hole is so compact that you're able to get much closer to the center of gravity than you would have been able to do when the star was a supergiant.

Gravitation between two bodies is governed by the mass of the two objects, and by the separation between them. That's why they don't drain the entire universe like a bathtub - things far enough away don't get pulled any more than they did before it imploded.

Black do devour companion stars, etc. This has been observed, but there are also many examples of companions devouring each other when neither is a black hole, so it's not the fact that one body is a black hole behind this phenominon.

Answer 2

Basically, the universe isn't old enough. Not enough time has passed for enough BHs to be formed from dying stars, that all other matter is within their gravitational reach. Gravity does extend infinitely in distance at the speed of light, but as other posters have said here, its strength drops off dramatically with distance.

We now live in what some cosmologists call the Stelliferous Era - the range of billions of years in which there is enough stray matter around that stars can be born, live out their cycles, and die. But that entire era is predicted to be a brief blink in the entire age of the future universe, which might go on forever. Even if all of the available matter in the universe eventually spirals down one gravitational drain or another, the space around the BHs will still exist, and so the universe will still exist, just as a place ill-suited to supporting life. Even the Black Hole Era will eventually end due to Hawking radiation from the holes, many trillions of years later.

Cosmologists like Hawking who theorize about the creation of many, many universes outside of our own have posited that if a universe was created with a terrific amount of mass in it, the entire thing could stop expanding and contract into a singularity not unlike a BH, called the "Big Crunch". That could indeed be the end of that entire universe.

Answer 3

The history channel discussed this briefly on a show several days back. It is true that black holes have the strength to take in anything, including light. So yes, If one was to get close enough to the earth it would take it in. As far as it being a drain, meaning inevitably the earth would be sucked into one, I'm not sure. If it were somehow true then I imagine the process would take a near infinite amount of time, considering most data indicates the universe is infinite.

Answer 4

Gravity is actually the weakest of the four fundamental forces. You have the whole mass of the Earth pulling you down but think how easy it is to just jump in the air and lift your body off the ground. Also, gravity's effects weaken considerably with distance. There is a supermassive black hole at the centre of our galaxy but it has virtually no effect on the Earth as it orbits the sun, because the sun is much closer.

Answer 5

Black holes are just like any other object once you're a few kilometers away from them; their gravitational attraction is proportional to thieir mass. Most black holes are dead stars; they exert the exact same gravitation on the rest of the universe when they become black holes as when they were living stars.

The picture of a Black Hole as a huge omnivorous vacuum cleaner is only appropriate extremely close to the hole.

Answer 6

To put it simply:

- Gravity exhibits a force within a field on objects which possess mass.
- If an object with mass is not within this field, then it will not experience a force, in the case of a black hole, it will not be sucked into it.
- Since the size of a black hole's field doesn't extend beyond its field, it can't suck up the entire universe.

Answer 7

Everyone seems to think a black hole is like some giant vacuum cleaner; it isn't. It's just a mass that is compressed and has the same effect as the star or whatever collapsed into it. Unless we drift into it's quite normal gravitational field, it has no effect on anything else.

Answer 8

Because they are made of dead stars. Therefore the black hole keeps tha same amount of total mass as the star before it had. Thus it doesn't create anymore gravity than that sun had and doesn't effect the orbits of the things around it unless they are literally right on top of it.

Answer 9

Gravity propogates at the speed of light and it loses power the further away from the massive body, and it pulls with a measurable energy. Therefore blacks holes do not have the range to suck in the whole universe quickly.

Answer 10

The only correct answer is this (as simple as i can): As black holes attract mass, they lose energy. When they attract mass they finaly evaporate. That's why the whole unverse won't be sucked into one black hole. The hole will evaporate