If humans do not destroy themselves they may spread beyond the earth into a universe that could last almost forever. Life would have tunnelled through its moment of maximum jeopardyby Martin Rees / January 20, 2002 / Leave a comment
Over the past few centuries, the earth has aged spectacularly. Its creation has been moved back from 6pm on Saturday, 22nd October, 4004 BC, as calculated by the 17th-century scholar and Archbishop of Armagh, James Ussher, to a time and date some 4.5 billion years earlier. The story of life has been stretched back almost as far, and the story of complex, multicellular life-forms-relative newcomers-has itself been almost a billion years in the making. As a result, the way we see the world has changed profoundly. Not only can we now have some sense of the millions of years it takes to raise and then level mountains, or to open and then close oceans, we also have the clearest evidence of humanity’s absence throughout those ages. To Ussher’s mind, the creation of the world and the creation of humanity were within a week of one another; to our modern minds, the two events are unimaginably far apart. There was a vast absence before us, a physical and biological world untouched by introspection, and its record stares out at us from every rock.
If the earth’s past has been stretched, what of its future? To those of Ussher’s faith, the end of the world was a certainty and to some of his contemporaries history was already nearing its close. Sir Thomas Browne wrote, “the world itself seems in the wane. A greater part of Time is spun than is to come.”
To look forward, we must turn from geology to cosmology. Current cosmology suggests a future that, if not infinite, dwarfs the past as much as the depths of time we now accept dwarf Ussher’s exquisite estimates. What it cannot tell us, though, is whether these vast expanses of time will be filled with life, or as empty as the earth’s first sterile seas. In the aeons that lie ahead, life could spread through the entire galaxy, even beyond it-and outlast it too. But life could also snuff itself out, leaving an eternity as empty as the space between the stars.
Getting very hot To begin at the beginning, we can, with some confidence, trace cosmic history back to its first few seconds, some 12 billion years ago. But in response to the fundamental question, “what happened before the beginning?” we cannot do much better than St Augustine in the 5th century, who sidestepped the issue by arguing that time…