I see, hear, and read about black holes and their consumption power often. They grow as they consume. Eventually, as they keep growing and consuming, wouldn’t they combine and continue the process until they become so large as to devour everything in existence?
In: Physics
On extreme time scales like quintillions of years there are two main things that will happen to bodies. They either remain gravitationally bounded to a galaxy or a group of galaxies or flung out by some other object.
In the latter case these objects will inevitably end up being on their own as the universe is dominated by dark energy and so unbounded bodies end up being separated and continue in their practically own universe.
For gravitationally bound system orbits will decay as the accelerated masses radiate like accelerated charges but in our case they radiate gravitational waves. This very slowly kills their kinetic energy and they end up spiralling into the center most likely a black hole.
So you’ll end up with black holes, rogue planets, other stellar corpses separated by ever increasing distances.
People also underestimate how *enormous* and *empty* universe is. Black holes routinely exist at the center of galaxies and yet that doesn’t mean it’s eating its “host galaxy” all the time just waiting for it to be so large to start eating up another galaxy. Another galaxy might be hundreds of light years away and between that there’s *close to nothing*. I imagine even if a black hole would grow that big, it would run out of stuff to devour and slowly dissipate instead.
No. The universe is expanding too rapidly to allow this to happen. Certainly black holes will continue to devour matter, but they’ll only have limited amounts close enough. Also, they only devour matter, not spacetime itself, so the universe will continue long after every black hole has evaporated.
Black holes are really powerful but really really small. A black hole the mass of the sun, for instance, is roughly the size of a city. They’ll gobble up anything that’s really close to them, but things in space are usually really far apart, usually farther away than the danger zone of a black hole. What’s more, they’re very messy eaters, with a lot of their meals getting shot out along their axis of rotation.
All in all, even if it does happen, it won’t be for many zillions (that’s an exact figure) of years.
Honestly, the answer to that question at this time in ELI5 is “Yes, no and maybe.” It all depends on some theories that conflict with each other based on current data and observations. The James Webb telescope is providing new data that is making huge strides in clarifying some things but raising other questions. It is an extremely exciting time for the field. Even for a someone like myself that doesn’t follow closely but was a physics minor in college and kept up on the big stuff.
I don’t know if this type of comment is against the rules, but I love the theories by William James Sidis on this. He wrote his theories years before “black hole” was even a term. Worth checking out.
There’s a misconception that black holes are some incredible gravity super-vacuum in space.
They sort of are, but probably not in the same way you’d think.
A black hole with a million solar masses has the exact same gravitational power as a normal star with a million solar masses. The black hole is simply denser which allows math to do some funny stuff when you get way too close to it.
But from a distance, you wouldn’t notice a thing gravity-wise.
The Universe is going to end with heat death. We will lose all potential energy and everything will be black and dead. This is going to take a VERY long time though.
There are two ways we think the universe could end. The first is the Big Crunch. The idea is there’s enough mass in the universe that gravity begins to dominate, and start pulling everything back together. The universe starts contracting, and eventually everything is crushed down into a single point, called a singularity. This is probably the closest to what you’re thinking of.
The other way, which is what we think is probably going to happen, is that there’s not enough mass in the universe for gravity to dominate. Instead, the universe just keeps expanding forever. Eventually, after trillions of years, all the stars burn out, all the energy is spent, all the black holes evaporate into nothing. The universe is dead and dark and nothing ever happens any more. Time becomes meaningless because nothing moves, so nothing can measure time passing. That’s the Heat Death of the universe.
Black holes grow as they consume matter, but they also constantly lose mass via Hawking radiation. They can’t grow forever.
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