What Dark Energy Means For The End of Time
On the mysteries of dark energy and the fate of the universe
Long ago, long before humankind had dreamed of science, of forces and atoms, of dark matters and dark energies filling the void, our deep ancestors looked up at the splendor of the night and wondered. How, some child must have asked, did it all begin? And then, after some thought: how will it all end?
For generations we lacked the tools to grasp the significance of those questions. Beginnings and endings belonged — and to some extent, still belong — to the realm of the gods; to beings far more powerful than humans can dream of becoming. Only the gods could create something where there was nothing, only they could breathe life into a dead cosmos.
Eventually, however, we began to probe more deeply. We learned of the atoms and their constituents; we found ways to manipulate them, and thus harnessed the hidden powers of nature. We uncovered the laws of gravity, and of the electric and nuclear forces. We built power stations, unleashed devastating weapons, and reached out to the planets and beyond.
And yet, the big questions — how it began, how it will end, and why it is here at all — remain stubbornly elusive. Yes, we have some answers — the Big Bang Theory, for instance, is generally accepted, and modern cosmology has a reasonable idea of what has happened since. But much is still mysterious.
Indeed, the explanations dreamed up by modern cosmology rely on two big unknowns: dark matter and dark energy. We have no real idea of the nature of these two entities. And yet without them, it seems galaxies would not form or hold together, stars would not fill the skies, and life would never have got started. There would have been, in other words, no real beginning.
What these two mysteries mean for the future, however, is even harder to say. Without a proper understanding of dark energy, we cannot say if the universe will expand forever or eventually collapse. We do not know if the stars and galaxies will fade away, or if everything will one day be reborn in a second big bang.
Put simply, we still do not know how it will all end.
I. When Gravity Ruled The Cosmos
At first, the question of endings seemed to be one of gravity.