Dear Friends,
Be Well.
David
Why The Universe Is Not a Computer After All
The idea that our Universe is a giant cosmic computer
pervades modern science. Now one physicists says this assumption is dangerously
wrong
One of the driving forces in modern science is the
idea that the Universe “computes” the future, taking some initial state as an
input and generating future states as an output. This is a powerful approach
that has produced much insight. Some scientists go as far as to say that the
Universe is a giant computer.
Is this a reasonable assumption? Today, Ken Wharton at
San Jose State University in California, makes an important argument that it is
not. His fear is that the idea of the
universe as a computer is worryingly anthropocentric. “It’s basically the assumption that the way
we humans solve physics problems must be the way the universe actually
operates,” he says.
What’s more, the idea has spread through science
without any proper consideration of its validity or any examination of the
alternatives. “This assumption…is so strong that many physicists can’t even
articulate what other type of universe might be conceptually possible,” says
Wharton.
He argues that a close look at the notion of the
cosmos as a computer reveals important problems. Wharton examines several. For
example, a computation involves three steps. First, the physical world has to
be mapped onto some mathematical state. Next, this state mathematically evolves
into a new state. And finally, the new state is mapped back onto the physical
world.
In quantum mechanics, this can only happen if this
final step is probabilistic. As Wharton puts it: “Not even the universe knows
which particular outcome will occur.”
And yet, when the universe is measured, a specific
outcome does occur. The operation of a
computer cannot account for this. For Wharton, this is a crucial flaw
that most physicists just overlook.
It’s also an important clue that idea of the universe
is a computer is merely an assumption and one that has never been rigorously
questioned. “It is the least-questioned (and most fundamental) assumptions that
have the greatest potential to lead us astray,” he says.
The consequences of this are profound. “Thanks to this
deep bias, it’s possible that we have missed the bigger picture: the mounting
evidence that the fundamental rules that govern our universe cannot be
expressed in terms of [a traditional computation].”
To demonstrate the point, Wharton spends a significant
part of his paper explaining an alternative view of the cosmos which does not
rely on traditional computation. This is Lagrange’s formulation of the laws of
physics based on the principle of least action.
An example is the principle that light travels the
shortest distance between two points. Lagrange’s method is essentially to
stipulate the start point and end point, examine all possible paths and choose
the shortest. “In this view, the reason light bends at an air/water interface is not because of any
algorithm-like chain of cause-and-effect, but rather because it’s globally more efficient,” explains Wharton.
Anybody familiar with this approach will know its
great elegance and beauty. But critics
ask how the light ray can know its end point when it starts its journey.
Wharton says these critics argue like this: “Yes, [Lagrange’s method] may be
beautiful, it may be powerful, but it’s not how our universe really works. It’s
just a useful trick we’ve discovered.”
But this argument is itself powerfully
anthropocentric, says Wharton. It assumes the Universe must work in the way we
solve problems–that the Universe is as “in the dark” about the future as we
are.
Of course, there are plenty of good arguments for
thinking that the Universe works like a conventional computer. The point
Wharton makes is that there are other ways of thinking about the cosmos too and
that these may provide important new insights. We ignore them at our peril.
Interesting reading.
Ref: arxiv.org/abs/1211.7081: The Universe As Not A
Computer
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