Just when I was concerned about what’s going to happen in just 100bn years, something even weirder has emerged.
After the age of stars and planets – starting in a thousand trillion years’ time – the stars will have dimmed. Gone nova, neutron, or just plain browned out. And the universe will be a much less interesting place for a long, long time. (Some 10^25 years or so.) No light, little heat, less hope. No place for planets; they’ll have burned, frozen, or been crushed to dust. Nothing warm, nothing wet, no life-spawning rocky forests or carbon-rich oceans. Life will have ended.
And yet – life will re-emerge and flourish for a time, in that long dark twilight, due to a statistical fluke every hundred billion years or so. And if that life evolves intelligence (which takes less than four billion years, in the only example we know of) there’s only one thing for them to learn: that they are utterly alone.
Every so often in that dimly diffuse universe, two brown dwarfs – dead suns, balls of hydrogen taking their time to dim after the fusion fires go out – will pass into each others’ orbits and collide. If they hit hard enough, the kinetic energy liberated will restart the fires. Hydrogen will start fusing again deep in their hearts.
(These will be incredibly rare events. But 10^25 years is a lot of time for rare events to happen.)
Amazingly, a new sun will light up the endless night. A star not too different from the sun. And the corona of dust around the two-made-one may form planets, some in a habitable zone where liquid water can exist on their surfaces.
And here’s the Big Joke: There, at the other end of midnight, there’ll be civilisations again.
Such events will only occur once every hundred billion years or so. But the ‘degenerate age’ of dead suns and frozen stars will go on for far, far longer – 10^25 years, a trillion trillion decades. Statistically, over the span of that epoch, several thousand planets, some with intelligent life on them, will be created out of the darkness, perhaps one or two per million galaxies.
And here’s the weird part: they will be truly alone.
Us earthlings are lucky enough to know the universe in its first flush of youth. We can look up at a crowded sky, a vast grab-bag of galaxies ripe with possibilities. We can study them, dream about them. And – one distant day – we’ll travel among them.
But the astronomers and engineers of those distant civilisations will be mere statistical flukes amid a dying universe. Their skies will be dark. The distance and rate of expansion between their dead galaxies puts everything beyond their causal horizon, and even if they found a way around the speed limit, all that’s there is more dead black stuff. There’s nothing around them, nothing beyond their planet and its chance-created sun.
Those people will have no … dreams.
Their dreams won’t be shattered by discovering this, because they’ll never have anything to dream about. Their lives really will be for nothing. Whatever they achieve, whatever art or science or architecture they create, will all be for nothing, because there’s nobody left to share it with.
They really will be alone. And there’ll be nothing they can do about it. They’ve turned up to a party when the host has long since switched out the lights and gone to bed.
I thought having just 100bn years to explore before the rest of the universe races beyond our causal horizon was pretty depressing. But those future folk have really got it bad.