How Long Humanity Could Survive

How much future is there, really? Provided humanity doesn’t do something collosally stupid and self-destruct, how long could homo sapiens – or our descendants – continue to grace this universe?

When looking back at history, we often feel dwarfed by the huge measures of time depicted in the age of the universe, compared to which the entire existence of modern humans scrapes in as about two thousandths of a percent. Even compared only to our own planet, we’re not doing much better at five thousandths of one percent. And yet, the amount of time humanity could potentially thrive is far, far huger; orders of magnitude larger.

On a personal level, the span of the future seems simple. The life expectancy average of the world is about 71, as of 2016. Of course, that doesn’t take into account various life extension efforts that might bear fruit in the coming decades. It’s not unreasonable to say you have a significant chance of living to one thousand years old, and if you have the opportunity and choose to upload, you could exist for as long as computers keep running, which could be a very long time indeed.

The Earth will continue to exist for some 7 or 8 billion years, before being vaporised when our sun enters a new stage in life – that of a red giant, swelling and dimming admit dies. But humans will probably have figured out a way off the planet by then, so that need not be the end, although our descendants will likely not be human as we currently think of the term. Even if humanity goes without cyborgization or genetic tinkering, 7 billion years is longer than the Earth has existed so far, and far, far more time than is needed for evolution to change humanity into a whole constellation of new species. That’s a vast amount of future, and that’s only the beginning.

The spirit of humanity could continue onwards, even as the sun goes out some 2 billion years after the destruction of the Earth. By that point, we can expect to be safely spread out among the stars – indeed, even if we set out on our ships only just as the Earth was disintegrating, we would only need to be travelling at 2 miles per hour to safely make it to our nearest stars, Alpha Centauri, before the sun went out.

Even when all the stars have died, hundreds of trillions of years from now, humanity’s descendants may yet persist, extracting energy from black holes in the endless, starless night. In fact, that epoch may be our longest yet, by a huge, huge margin. Bigger black holes dissolve much more slowly than smaller ones, and according to current calculations, a black hole with the mass of the sun would last about 10 to the 67th years before dissolving – to put that in perspective, the universe has currently existed for only 14 times 10 to the 9th years. Except we’re not stuck with a black hole the size of the sun – the black hole at the center of the milky way is 100 thousand times more massive than our sun. Scientists predict that the largest black holes that currently exist could be 10 billion times the mass of the sun, and they’ll only get bigger.

If we don’t blow ourselves up, humans and the descendants of humans could be around eons upon eons longer than the stars.

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