If you’ve ever thought life was actually a dream, take comfort. Some pretty distinguished scientists may agree with you. Philosophers have long questioned whether there is in fact a real world out there, or whether “reality” is just a figment of our imagination.
Then along came the quantum physicists, who unveiled an Alice-in-Wonderland realm of atomic uncertainty, where particles can be waves and solid objects dissolve away into ghostly patterns of quantum energy.
Now cosmologists have got in on the act, suggesting that what we perceive as the universe might in fact be nothing more than a gigantic simulation.
The story behind this bizarre suggestion began with a vexatious question: why is the universe so bio-friendly? Cosmologists have long been perplexed by the fact that the laws of nature seem to be cunningly concocted to enable life to emerge. Take the element carbon, the vital stuff that is the basis of all life. It wasn’t made in the big bang that gave birth to the universe. Instead, carbon has been cooked in the innards of giant stars, which then exploded and spewed soot around the universe.
The process that generates carbon is a delicate nuclear reaction. It turns out that the whole chain of events is a damned close run thing, to paraphrase Lord Wellington. If the force that holds atomic nuclei together were just a tiny bit stronger or a tiny bit weaker, the reaction wouldn’t work properly and life may never have happened.
The late British astronomer Fred Hoyle was so struck by the coincidence that the nuclear force possessed just the right strength to make beings like Fred Hoyle, he proclaimed the universe to be “a put-up job”. Since this sounds a bit too much like divine providence, cosmologists have been scrambling to find a scientific answer to the conundrum of cosmic bio-friendliness.
The one they have come up with is multiple universes, or “the multiverse”. This theory says that what we have been calling “the universe” is nothing of the sort. Rather, it is an infinitesimal fragment of a much grander and more elaborate system in which our cosmic region, vast though it is, represents but a single bubble of space amid a countless number of other bubbles, or pocket universes.
Things get interesting when the multiverse theory is combined with ideas from sub-atomic particle physics. Evidence is mounting that what physicists took to be God-given unshakeable laws may be more like local by-laws, valid in our particular cosmic patch, but different in other pocket universes. Travel a trillion light years beyond the Andromeda galaxy, and you might find yourself in a universe where gravity is a bit stronger or electrons a bit heavier.
The vast majority of these other universes will not have the necessary fine-tuned coincidences needed for life to emerge; they are sterile and so go unseen. Only in Goldilocks universes like ours where things have fallen out just right, purely by accident, will sentient beings arise to be amazed at how ingeniously bio-friendly their universe is.
It’s a pretty neat idea, and very popular with scientists. But it carries a bizarre implication. Because the total number of pocket universes is unlimited, there are bound to be at least some that are not only inhabited, but populated by advanced civilisations – technological communities with enough computer power to create artificial consciousness. Indeed, some computer scientists think our technology may be on the verge of achieving thinking machines.
It is but a small step from creating artificial minds in a machine, to simulating entire virtual worlds for the simulated beings to inhabit. This scenario has become familiar since it was popularised in The Matrix movies.
Now some scientists are suggesting it should be taken seriously. “We may be a simulation … creations of some supreme, or super-being,” muses Britain’s astronomer royal, Sir Martin Rees, a staunch advocate of the multiverse theory. He wonders whether the entire physical universe might be an exercise in virtual reality, so that “we’re in the matrix rather than the physics itself”.
Is there any justification for believing this wacky idea? You bet, says Nick Bostrom, a philosopher at Oxford University, who even has a website devoted to the topic ( http://www.simulation-argument.com). “Because their computers are so powerful, they could run a great many simulations,” he writes in The Philosophical Quarterly.
So if there exist civilisations with cosmic simulating ability, then the fake universes they create would rapidly proliferate to outnumber the real ones. After all, virtual reality is a lot cheaper than the real thing. So by simple statistics, a random observer like you or me is most probably a simulated being in a fake world. And viewed from inside the matrix, we could never tell the difference.
Or could we? John Barrow, a colleague of Martin Rees at Cambridge University, wonders whether the simulators would go to the trouble and expense of making the virtual reality foolproof. Perhaps if we look closely enough we might catch the scenery wobbling.
He even suggests that a glitch in our simulated cosmic history may have already been discovered, by John Webb at the University of NSW. Webb has analysed the light from distant quasars, and found that something funny happened about 6 billion years ago – a minute shift in the speed of light. Could this be the simulators taking their eye off the ball?
I have to confess to being partly responsible for this mischief. Last year I wrote an item for The New York Times, saying that once the multiverse genie was let out of the bottle, Matrix-like scenarios inexorably follow. My conclusion was that perhaps we should retain a healthy scepticism for the multiverse concept until this was sorted out. But far from being a dampener on the theory, it only served to boost enthusiasm for it.
Where will it all end? Badly, perhaps. Now the simulators know we are on to them, and the game is up, they may lose interest and decide to hit the delete button. For your own sake, don’t believe a word that I have written.
Paul Davies is professor of natural philosophy at Macquarie University’s Australian Centre for Astrobiology. His latest book is How to Build a Time Machine. Copyright © 2004. The Sydney Morning Herald