Just in case it’s been weighing on your mind, you can relax
now. A team of theoretical physicists from Oxford University in the UK has
shown that life and reality cannot be merely simulations generated by a massive
extraterrestrial computer. The finding – an unexpectedly definite one – arose
from the discovery of a novel link between gravitational anomalies and
computational complexity.In a paper published in the journal Science Advances, Zohar
Ringel and Dmitry Kovrizhi show that constructing a computer simulation of a
particular quantum phenomenon that occurs in metals is impossible – not just
practically, but in principle.

The pair initially set out to see whether it was possible to
use a technique known as quantum Monte Carlo to study the quantum Hall effect –
a phenomenon in physical systems that exhibit strong magnetic fields and very
low temperatures, and manifests as an energy current that runs across the
temperature gradient. The phenomenon indicates an anomaly in the underlying
space-time geometry.

Quantum Monte Carlo methods use random sampling to analyse
many-body quantum problems where the equations involved cannot be solved
directly. Ringel and Kovrizhi showed that attempts to use quantum Monte
Carlo to model systems exhibiting anomalies, such as the quantum Hall effect,
will always become unworkable.They discovered that the complexity of the simulation
increased exponentially with the number of particles being simulated. If the complexity grew linearly with the number of particles
being simulated, then doubling the number of partices would mean doubling the
computing power required. If, however, the complexity grows on an exponential
scale – where the amount of computing power has to double every time a single
particle is added – then the task quickly becomes impossible.

The researchers calculated that just storing information about
a couple of hundred electrons would require a computer memory that would
physically require more atoms than exist in the universe. The researchers note that there are a number of other known
quantum interactions for which predictive algorithms have not yet been found.
They suggest that for some of these they may in fact never be found.

And given the physically impossible amount of computer grunt
needed to store information for just one member of this subset, fears that we
might be unknowingly living in some vast version of The Matrix can now be put
to rest.

Time and time again science has made similar proclamations only to have to the old facts be discarded by the new science. Considering what science knows about computers and the newness of computer science knowledge, nothing is really impossible in the field.

ReplyDelete