Just what the universe needs right now: A black hole with wind Scientists have observed larger ring-like structures around the supermassive black hole at the center of galaxy M87 than when it famously became the subject of a photoshoot in 2019. The study, published in the science journal Nature today, also reveals the influence of wind on the black hole's accretion jets – emitted by …
The answer to that one is:
1) Black holes consume everything else.
2) Wait another umpty-trillion years and they all evaporate due to Hawking radiation.
3) Universe becomes an amorphous, featureless, warm expanse of nothing.
4) With the cessation of entropic decay and nothing to differentiate between one moment and the next, time stops.
5) With no time, nothing to gauge space by and no way to compare temperature, it become uncertain whether the universe is huge and warm or sizeless and hot.
6) Hot singularity containing entire universe explodes...
I am not an expert, but I am fairly sure it is well understood now that the universe will continue to expand, with everything getting further apart, and has no chance of collapsing back again.
Of course, new discoveries could change our underlying scientific understanding but, with current science, we will just get further and further apart. Already most of the obversable universe is completely unreachable to us (we cannot send even a speed-of-light signal fast enough that it can ever catch up the objects we observe from the past, which are all moving away from us).
Happy to be corrected when an actual boffin joins the discussion!
Even with what we know now, that is not the only possible end.
A new theory has come to light : black holes just might be dark energy. In that case, who knows what will happen when they have all evaporated ? Maybe our Universe will stop expanding, stabilize over untold trillenia, then start to contract again, going right back to the Great Collapse, and then everything starts again. Who knows ?
I don't think we ever will for sure. But that should definitely not stop us from trying to find out.
Once all mass is gone (down the black holes, which then evaporate into nothingness), so is gravity, so even if dark energy is gone too, there would be no driving force for a contraction. At least none we are currently aware of.
The universe is most likely bound to become a huge empty (except quantum fluctuations) void. One thing is sure, nobody will be there to see it.
I like the way that you link to a video about 'black holes just might be dark energy', to come up with a way to have a Great Collapse ...... when the video actually concludes that it's plausible but very unlikely, and has at least one red flag amongst the evidence they present for the idea.
Next time perhaps link to something that supports the idea.
Nah, the accretion disk is just the messy dinner plate holding the black hole's current dinner: Ripped apart stars, which will partly be swallowed, partly just expelled at relativistic speeds. Just like a baby, actually.
So, each time a new star comes too close and is "spaghettified" (cute term for "ripped apart") by the black hole's tidal forces, the accretion disk gets bigger/fuller. It then empties over time, half eaten, half ejected, till the plate is eventually empty. Black holes which haven't caught anything to eat for a while don't have an accretion disk, and are thus almost invisible. You can only detect them because of their gravitational lensing.
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