Far out cosmology: we've pictured our own black hole (Introduction)

by David Turell , Sunday, July 17, 2022, 00:31 (643 days ago) @ David Turell

How we think it ends:

https://bigthink.com/starts-with-a-bang/how-will-the-universe-end/?utm_source=mailchimp...

"On timescales of a few billion years, we’re pretty confident of what will happen, both locally and cosmically. The Sun will heat up, swell, boil Earth’s oceans, and eventually become a red giant, dying shortly thereafter. The Local Group will remain bound, and the galaxies within it will attract and merge together, triggering new star-formation and depleting our gas. Four billion years from now, the Milky Way and Andromeda will merge together, creating a new galaxy known as Milkdromeda.

"By the time another 10-to-15 billion years have passed, all of the galaxies in the Local Group should experience a gravitational encounter with Milkdromeda, where they’ll be devoured and cannibalized. As the gas within these galaxies forms new generations of stars, it also gets depleted; over time, the star-formation rate will continue to plummet. Without the fuel for forming new stars in great numbers, old stars will die faster than new ones are being born; the number of living stars in our galaxy will start to drop.

"Meanwhile, all the other groups of galaxies will accelerate away from our own. Just as the Local Group becomes more concentrated, so will the other groups and clusters, but only individually.

***

"There are some open questions, however, that could change the story in subtle ways.

"Dark energy may not be a cosmological constant, but could evolve with time, leading to either a Big Crunch or a Big Rip, or something else entirely. We may not be in the true vacuum state of the Universe, and if we experience vacuum decay, so could our fate. Atoms that we presently think are stable could wind up decaying on long enough timescales. And perhaps, although we don’t think it’s the case, it’s plausible that a gravitational interaction in a nearby galaxy group could lead to other members someday joining our Local Group. We can only extrapolate our future based on the limits of what’s known today.

"But that said, we sure do know a lot about what to expect in our far, distant cosmic future! There will come an era where all the distant galaxies beyond our own have disappeared from view. After that, we’ll reach a time where the stars have all gone out, and where all the stellar remnants have faded away. Although the darkness will be punctuated by flashes of light, eventually, the stellar remnants in our galaxy will all be ejected, and the last remaining vestige of matter — our central, supermassive black hole — will decay away. The timescales are tremendous, but still finite; it’s a solemn reminder to enjoy the Universe in all its glory while it’s still here. In this Universe, it truly appears that nothing lasts forever."

Comment: its Ethan Siegel again with his opinion. For those of us who believe in God, there is another issue: Is our universe one and done, were there others before or are others coming? We only live in this one, our only experience, so we will never know.