by John Tierney
August 14, 2007
Until I talked to
Nick Bostrom, a philosopher at
Oxford University, it never occurred to me that our universe might
be somebody else’s hobby.
I hadn’t imagined that the omniscient,
omnipotent creator of the heavens and earth could be an advanced
version of a guy who spends his weekends building model railroads or
overseeing video-game worlds like the Sims.
But now it seems quite possible. In fact, if you accept a pretty
reasonable assumption of Dr. Bostrom’s, it is almost a mathematical
certainty that we are living in someone else’s computer simulation.
This simulation would be similar to
the one in “The Matrix,” in
which most humans don’t realize that their lives and their world are
just illusions created in their brains while their bodies are
suspended in vats of liquid.
But in Dr. Bostrom’s notion of reality,
you wouldn’t even have a body made of flesh. Your brain would exist
only as a network of computer circuits.
You couldn’t, as in “The Matrix,” unplug your brain and escape from
your vat to see the physical world. You couldn’t see through the
illusion except by using the sort of logic employed by Dr. Bostrom,
the director of the Future of Humanity Institute at Oxford.
Dr. Bostrom assumes that technological advances could produce a
computer with more processing power than all the brains in the
world, and that advanced humans, or “posthumans,” could run
“ancestor simulations” of their evolutionary history by creating
virtual worlds inhabited by virtual people with fully developed
virtual nervous systems.
Some computer experts have projected, based on trends in processing
power, that we will have such a computer by the middle of this
century, but it doesn’t matter for Dr. Bostrom’s argument whether it
takes 50 years or 5 million years.
If civilization survived long enough to
reach that stage, and if the posthumans were to run lots of
simulations for research purposes or entertainment, then the number
of virtual ancestors they created would be vastly greater than the
number of real ancestors.
There would be no way for any of these ancestors to know for sure
whether they were virtual or real, because the sights and feelings
they’d experience would be indistinguishable. But since there would
be so many more virtual ancestors, any individual could figure that
the odds made it nearly certain that he or she was living in a
The math and the logic are inexorable once you assume that lots of
simulations are being run. But there are a couple of alternative
hypotheses, as Dr. Bostrom points out. One is that civilization
never attains the technology to run simulations (perhaps because it
self-destructs before reaching that stage).
The other hypothesis is that posthumans
decide not to
run the simulations.
“This kind of posthuman might have
other ways of having fun, like stimulating their pleasure
centers directly,” Dr. Bostrom says.
“Maybe they wouldn’t need to do
simulations for scientific reasons because they’d have better
methodologies for understanding their past. It’s quite possible
they would have moral prohibitions against simulating people,
although the fact that something is immoral doesn’t mean it
Dr. Bostrom doesn’t pretend to know
which of these hypotheses is more likely, but he thinks none of them
can be ruled out.
“My gut feeling, and it’s nothing
more than that,” he says, “is that there’s a 20 percent chance
we’re living in a computer simulation.”
My gut feeling is that the odds are
better than 20 percent, maybe better than even.
I think it’s highly likely that
civilization could endure to produce those supercomputers. And if
owners of the computers were anything like the millions of people
immersed in virtual worlds like Second Life, SimCity and World of
Warcraft, they’d be running simulations just to get a chance to
control history - or maybe give themselves virtual roles as
Cleopatra or Napoleon.
It’s unsettling to think of the world being run by a futuristic
computer geek, although we might at last dispose of that of classic
theological question: How could God allow so much evil in the world?
For the same reason there are plagues and earthquakes and battles in
games like World of Warcraft. Peace is boring, Dude.
A more practical question is how to behave in a computer simulation.
Your first impulse might be to say nothing matters anymore because
nothing’s real. But just because your neural circuits are made of
silicon (or whatever posthumans would use in their computers)
instead of carbon doesn’t mean your feelings are any less real.
David J. Chalmers, a philosopher at the Australian National
University, says Dr. Bostrom’s simulation hypothesis isn’t a cause
for skepticism, but simply a different metaphysical explanation of
our world. Whatever you’re touching now - a sheet of paper, a
keyboard, a coffee mug - is real to you even if it’s created on a
computer circuit rather than fashioned out of wood, plastic or clay.
You still have the desire to live as long as you can in this virtual
world - and in any simulated afterlife that the designer of this
world might bestow on you. Maybe that means following traditional
moral principles, if you think the posthuman designer shares those
morals and would reward you for being a good person.
Or maybe, as suggested by Robin Hanson, an economist at
George Mason University, you should try to be as interesting as
possible, on the theory that the designer is more likely to keep you
around for the next simulation.
Of course, it’s tough to guess what the designer would be like. He
or she might have a body made of flesh or plastic, but the designer
might also be a virtual being living inside the computer of a still
more advanced form of intelligence.
There could be layer upon layer
of simulations until you finally reached the architect of the first
simulation - the Prime Designer, let’s call him or her (or it).
Then again, maybe the Prime Designer wouldn’t allow any of
his or her creations to start simulating their own worlds. Once they
got smart enough to do so, they’d presumably realize, by Dr.
Bostrom’s logic, that they themselves were probably simulations.
Would that ruin the fun for the Prime
If simulations stop once the simulated inhabitants understand what’s
going on, then I really shouldn’t be spreading Dr. Bostrom’s ideas.
But if you’re still around to read this, I guess the Prime
Designer is reasonably tolerant, or maybe curious to see how we
react once we start figuring out the situation.
It’s also possible that there would be logistical problems in
creating layer upon layer of simulations. There might not be enough
computing power to continue the simulation if billions of
inhabitants of a virtual world started creating their own virtual
worlds with billions of inhabitants apiece.
If that’s true, it’s bad news for the futurists who think we’ll have
a computer this century with the power to simulate all the
inhabitants on earth.
We’d start our simulation, expecting to
observe a new virtual world, but instead our own world might end -
not with a bang, not with a whimper, but with a message on the
Prime Designer’s computer.
It might be something clunky like,
“Insufficient Memory to Continue
But I like to think it would be simple