The universe is cellular automaton in which reality is simply the readout of
a giant, fantastically complex computing machine. That’s the conclusion of Nobel
Prize-winning physicist Gerard ‘t Hooft, who says this also means that quantum
mechanics is a deterministic theory.
The key new feature of this deterministic model is that it specifically
allows for the quantum phenomenon of entanglement.
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One of the greatest scientific debates in history was fought over the nature
of quantum mechanics and the troubling consequences of a theory that is first
probabilistic rather than deterministic (God does not play dice) and second
nonlocal, meaning it allows the spooky action at a distance of entanglement.
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One way of resolving this problem is to assume that quantum mechanics is an
incomplete description of reality and that a full, deterministic description
can be achieved using some additional hidden variables. One theory, for
example, supposes that one hidden variable is a quantum particle’s position.
Another idea is that spooky action at a distance can be explained by hidden
variables that determine in advance how entangled particles will behave when
measured.
However, hidden variable theories have been largely discounted by quantum
theorists because their mathematical structure leads to a prediction about the
correlations between entangled particles that has been shown to be wrong in
numerous experiments. By this analysis, hidden variable theories cannot underlie
quantum mechanics.
But there may be classes of hidden variable theories that are not covered by
this argument.
Today, ‘t Hooft said he has found one of them: a new class of deterministic
models of the universe that allow for entanglement. Curiously, these are based
on cellular automaton, a computing device consisting of a grid of cells that can
be in various states depending on the states of the adjoining cells.
He’s not the first person to create a model of the universe out of a cellular
automaton. Independent scientist Stephen Wolfram believes the universe is
better modeled by cellular automata than by the conventional laws of physics.
Ed Fredkin, a computer scientist at MIT, has put forward a similar idea. And mathematician
John Conway famously developed the Game of Life based on a cellular automaton.
So ‘t Hooft is in good company.
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However, his model has a number of deficiencies of which he seems to be well
aware. Perhaps the most serious is that the model lacks many of the most basic
symmetries that our universe enjoys, such as rotational symmetry.
But ‘t Hooft counters by saying, “One could argue that symmetry
arguments should not enter into the discussion of the interpretation of quantum
mechanics.” Although how you can make this argument isn’t clear.
I think it’s fair to say that ‘t Hooft’s ideas do not enjoy widespread
support. On the other hand, that is no real measure of their efficacy. The real
question is whether ‘t Hooft can make any predictions that would allow other
scientists to put his model to the test.
