http://www.msnbc.msn.com/id/50232422/ns/technology_and_science-science#.UNDIDG-CSSo
Be Well.
David
Is 'reality' unreal? Scientists work on a way to find out
Warner Bros.
A crew member of the Osiris hovercraft is
surrounded by monitors in an animated film based on "The Matrix." The
"Matrix" film series suggested that our everyday experience is basically
a computer simulation. Researchers are now proposing a way to test that
way-out hypothesis.
What if everything — all of us, the world, the universe — was
not real? What if everything we are, know and do was really just
someone's computer simulation?
The notion that our reality was some kid on a couch in the far future
playing with a computer game like a gigantic Sim City, or Civilization,
and we are the player's characters, isn't new. But some physicists now
think they know of a way to test the concept. Three of them propose to
test reality by simulating the simulators.
Martin Savage, professor of physics at the University of Washington,
Zohreh Davoudi, one of his graduate students, and Silas Beane of the
University of New Hampshire would like to see whether they can find
traces of simulation in cosmic rays. The work was uploaded in arXiv, an online archive for drafts of academic research papers.
The notion that reality is something other than we think it is goes
far back in philosophy, including Plato and his Parable of the Cave,
which claimed reality was merely shadows of real objects on a cave wall.
Sixteenth-century philosopher-mathematician René Descartes thought he
proved reality with his famous "I think, therefore I am," which proposed
that he was real and his thoughts had a reality.
Then, in 2003, a British philosopher, Nick Bostrom of the University
of Oxford, published a paper that had the philosophy and computer
science departments buzzing.
The Matrix hypothesis
Bostrom suggested three possibilities:
"The chances that a species at our current level of development can
avoid going extinct before becoming technologically mature is negligibly
small," "almost no technologically mature civilizations are interested
in running computer simulations of minds like ours,” or we are "almost
certainly" a simulation.
All three could be equally possible, he wrote, but if the first two
are false, the third must be true. "There will be an astronomically huge
number of simulated minds like ours," Bostrom wrote.
His suggestion was that our descendants, far in the future, would
have the computer capacity to run simulations that complex, and that
there might be millions of simulations, and millions of virtual
universes with billions of simulated brains in them.
Bostrom's paper came out four years after the popular film, "The
Matrix," in which humans discover they were simulations run by
malevolent machines. The popularity of the film possibly contributed to
the attention to Bostrom’s paper received at the time, but nothing came
of it.
"He put it together in clear terms and came out with probabilities of
what is likely and what is not," Savage said. "He crystallized it, at
least in my mind."
Looking for anomalies
In the movie and in Savage's proposal, the discovery that
reality was virtual came when unexpected errors showed up in life,
demonstrating imperfections in the simulation.
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Savage and his colleagues assume that any future simulators would use
some of the same techniques current scientists use to run simulations,
with the same constraints. The future simulators, Savage indicated,
would map their universe on a mathematical lattice or grid, consisting
of points and lines. This would not be an everyday grid but a
"hypercube" consisting of four dimensions, three for space, and one to
represent points in time.
A present-day example is lattice quantum chromodynamics, which
explores the effects of the strong nuclear force, one of the four
fundamental forces in the universe, on tiny elementary particles such as
quarks and gluons. In this approach, the particles jump from point to
point on a grid, without passing through the space between them. The
simulations cause time to pass in a similar way, like the frames of film
passing through a movie camera, so that the time that passed between
frames is not part of the simulation. This style of simulation requires
less computer power than treating space and time as a continuum.
Because Savage and his colleague assume that future simulators will
use a similar approach, he suggests looking at the behavior of very
high-energy cosmic ray particles to see whether there is a grid in the
energy as a start.
"You look at the very highest-energy cosmic rays and look for
distributions that have symmetry problems, which are not isotropic," or
the same in every direction, he said.
"Everything looks like it is on a continuum,” Savage said. "There is
no evidence to show that is not the case at the moment. We are looking
for something to indicate you don't have a space-time continuum."
Disturbance in the force
That disturbance in the force might be a hint that
something in reality is amiss. If the cosmic ray energy levels travel
along the grid, like following streets in Manhattan or Salt Lake City,
it probably is unlikely to be a simulation; if they unexpectedly travel
diagonally, reality may be a computer program.
Jim Kakalios, a physics professor at the University of Minnesota who
was not involved in the paper, said a test such as the one Savage
suggests may not prove anything. If they don't find the signatures, it
doesn't mean we are not a simulation; our descendants could have used a
different grid. If they do find something it also could mean “that's the
way space-time is and we never noticed before,” he said.
Two other questions arise. One is whether it is conceivable that
computers powerful enough to simulate our hugely complex universe ever
will exist. If so, it likely will be very far in the future.
The second question is linked: Will it ever be possible to simulate
human consciousness? After all, we run around thinking and feeling.
"Ultimately, the paper glides over the most interesting point: assume
we have infinite computing power and we can create this hypercube,"
Kakalios said. "They assume [the simulators] would know how to simulate
human consciousness."
We are aware of ourselves, he said, aware of our bodies, aware of
what is outside of our bodies, he said. Human consciousness is almost
indescribably complex.
For generations, science-fiction books — and some science books —
have hypothesized inserting our consciousness into computers so that we
essentially live forever. In "Caprica," a prequel to the television
program "Battlestar Galactica," a girl's consciousness is preserved in a
computer — and it becomes the basis for the evil cyborgs.
"We don't understand consciousness,” Kakalios said. "Neuroscience is
where physics was before quantum mechanics. It's a more interesting
problem than whether you can simulate protons and quarks."
Either way, however, Kakalios said the experiments on cosmic rays are
the kinds of projects scientists should be doing, regardless of the
simulation issue.
Joel Shurkin is a freelance writer based in Baltimore. He is the
author of nine books on science and the history of science, and has
taught science journalism at Stanford University, the University of
California at Santa Cruz and the University of Alaska at Fairbanks.
This report was originally published Dec. 14 by Inside Science News Service as "What If Reality Was Really Just Sim Universe?"
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