So, what if nothing really happens? What if the world isn't struck by meteors, destroyed by divine hand or blown to bits by scientists? Well, in the long run, we might sleep. Not just for the nights, but also during the day. We might even sleep our entire lives, from birth to death, without ever waking up. What's more: the survival of our species may depend on it.
Luckily, it will take some time before it gets that far. Something like one hundred trillion years, to be precise.
Our Universe expands. Ever since the Big Bang blew all matter, space and time into existence, the Universe grows. The Universe expands and cools, much like the fire cloud after an explosion gets bigger and colder. And that's exactly what astronomers see as they study the sky: all stars we see rush away from us and from each other at tremendous speeds.
But time is ticking. According to the latest insights, the expanding and cooling of the cosmos will go on and on and on. Galaxies and stars will be further and further apart. Stars will slowly become dimmer, as they move out of sight. The night sky will become darker and darker. And darker still, until there's absolutely nothing to be seen.
What's more, stars die. After a lifecycle of several to many millions of years (depending on their size), every star is destined to spew out its last bit of energy and collapse, becoming a cold `neutron star', a `white dwarf', or a black hole. As time passes, this will happen to more and more stars, creating a Universe full of burnt out dead stars and black holes.
And black holes `eat' other stars. A black hole has such immense gravity, that no star or planet can resist it. The increasing number of black holes will sweep the Universe clean, much like the devil in St. John's biblical vision of the Apocalypse sweeps the stars from the sky with its tail. It will become even darker still. And oh, by the way, our own Sun will die too, about 5,000 million years from now.
So what about us? Suppose man somehow finds a way to survive all these cataclysmic events.
Suppose humanity colonizes other, `safer' planets. And, for argument's sake, just suppose humanity is somehow able to dodge all those mean, black holes that scavenge the cosmos. What would life be like?
First, we would find ourselves in an increasingly cold, numbingly dark surrounding. We would be truly alone in the Universe.
But that's not the biggest problem. With the stars and the Sun long gone, we'll find ourselves in the midst of an energy crisis of unimaginable proportions. And terrible enough, in all the dark and the cold, we need energy more than ever.
Just hack up some atoms in a nuclear power plant, you might say. But that's not a good solution. By physical law, the energy within atoms decreases as the Universe expands.
And, bizarre as it may sound, the supply of atoms is ultimately limited. The matter on our planet is, of course, finite. And in the nothingness of the faded-out Universe, matter is hard to get at. It's either beyond reach or eaten up by black holes. And there's no more particles raining down on our planet from solar radiation, meteors or cosmic dust.
In the long run, we have to come up with something to adapt to our new environment. And `adapting' means more than getting used to cold feet and being able to see in total darkness: it means cutting drastically on our energy bill.
First, we'll have to get rid of our bodies. No, really! Our carbon-based bodies are very vulnerable to cold. They get damaged even when temperatures drop only a few degrees. It's absolutely certain there's no way life as we know it can survive for a substantial period of time in an expanded Universe.
But that's no big deal, Princeton physicist Freeman Dyson and many others suggest. We `only' have to transport our consciousness into something else. A cyborg, an interstellar cloud of particles maybe -- with one hundred trillion years ahead, we have plenty of time to come up with something.
So okay. Grudgingly, you've turned yourself into a cyborg. But in the long run, even that isn't enough. For one thing, thought itself costs energy. Just think of your computer doing its calculations: the thing simply wouldn't run if you didn't have it connected to a power source.
And what's worse, the universe gets colder still. This brings out other, very weird physical problems of its own. The speed of thought will drastically decline in extreme cold, Dyson demonstrated. So there you are, you've decided to become a cyborg, and now you find out you're sooooo slooow-witted.
And when temperatures drop even further, there's more trouble facing us poor former humans. It'll be so cold, even a cyborg would get into trouble. A point comes when organisms cannot lower their temperatures any further without becoming less complex -- in effect, dumbing down. Before long, life could no longer be regarded as intelligent.
It's here where sleep comes into play. As Dyson calculates, there's only one possibility to survive. We'd hibernate. By sleeping, our metabolic rates will drop, and we will be able to achieve an ever-lower body temperature. In fact, by spending an increasing fraction of our time asleep, eternal life would indeed be possible.
So you've become a slow-thinking robot that's asleep most of the time. Still, even that may not be enough. For example, what kind of alarm clock would you set to wake you up? Your alarm clock would have to operate reliably for a long, long time, using less and less energy. A curious but, scientifically speaking, dead serious problem, that no physicist has been able to answer yet.
And then there's the problem of thought. In the early 1980s, computer researchers realized that in principle it's possible to design a computer that doesn't dissipate energy while processing information. Isn't that great news for all those dormant cyborgs to come?
No, it isn't. To function, this computer -- that only is a theoretical possibility so far -- must never, NEVER discard any information. If it does discard only one bit of information, it will be like pulling the plug out of a bath tub: it would use up energy while calculating for ever more.
But thoughts are finite. Information is by definition stored in a finite amount of particles. Even in your cyborg brain, there will come a point where you would have to discard old information in order to store something new. And that IS a problem.
'All organisms would ever do is relive the past, having the same thoughts over and over again,' cosmologists Lawrence M. Krauss and Glenn D. Starkman estimate. 'Eternity would become a prison, rather than an endlessly receding horizon of creativity and exploration. It might be nirvana, but would it be living?'
Nope. Probably not. There you go, Mr. Cyborg: constantly asleep, and when awake only rethinking old thoughts.
Perhaps it's best our world is swallowed by one of those big, mean Black Holes after all.