Is The Universe A Virtual
By Paul Davies
Sydney Morning Herald
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 civilizations - 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 popularized 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 civilizations
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 analyzed 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 skepticism 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.