What Would Life Look Like If We Lived Forever?

Someone asked this question on Quora and this is what I answered:

It would be bizarre. We couldn’t die even if we tried to. Life would be like a video game where you continue the game immediately from where you left off if you died.

It is extremely hard to imagine what life would be like. Given the speed at which technology develops nowadays, ten years seems like a long time let alone a hundred years. A thousand years is absolutely beyond anybody’s imagination. It would go on a billion and a trillion trillion trillion trillion trillion years.

Our current understanding of how the universe will end is that it will keep expanding and cooling down forever at an accelerating speed. In the end, all matter will decay (if proton decay will take place, it is unconfirmed) until only photons will be left. The photons will continue cooling down until virtually nothing happens. If sentient beings were to find a way to remain sentient until that stage, their thoughts would slow down thus speeding the subjective passage of time. They would spend an eternity doing things we cannot even begin to imagine.

If, on the other hand, you mean what life would be like if nothing other than our physiological aging changed, an accident would be expected to kill you in about 25,000 years if you lived in a developed country. But that is only your life expectancy without the increased mortality that comes with age. You could die of an accident today or only after a million years. I don’t think our brains in their current form could handle living forever very well. Our personalities would probably be crystallized to an even greater degree than they do in real life as we age. We would probably become incredibly set in our ways.