CPS 100 Lecture Notes - Lecture 7: Roger Penrose, Socalled, Double-Slit Experiment
Quantum Theory of Consciousness
The American physicist Richard Feynman said this about the notorious puzzles
and paradoxes of quantum mechanics, the theory physicists use to describe the
tiniest objects in the Universe. But he might as well have been talking about the
equally knotty problem of consciousness.
Some scientists think we already understand what consciousness is, or that it is a
mere illusion. But many others feel we have not grasped where consciousness
comes from at all.
The perennial puzzle of consciousness has even led some researchers to invoke
quantum physics to explain it. That notion has always been met with skepticism,
which is not surprising: it does not sound wise to explain one mystery with another.
But such ideas are not obviously absurd, and neither are they arbitrary.
For one thing, the mind seemed, to the great discomfort of physicists, to force its
way into early quantum theory. What's more, quantum computers are predicted to
be capable of accomplishing things ordinary computers cannot, which reminds us
of how our brains can achieve things that are still beyond artificial intelligence.
"Quantum consciousness" is widely derided as mystical woo, but it just will not go
away.
Quantum mechanics is the best theory we have for describing the world at the
nuts-and-bolts level of atoms and subatomic particles. Perhaps the most renowned
of its mysteries is the fact that the outcome of a quantum experiment can change
depending on whether or not we choose to measure some property of the particles
involved.
When this "observer effect" was first noticed by the early pioneers of quantum
theory, they were deeply troubled. It seemed to undermine the basic assumption
behind all science: that there is an objective world out there, irrespective of us.
The most famous intrusion of the mind into quantum mechanics comes in the
"double-slit experiment". Imagine shining a beam of light at a screen that contains
two closely-spaced parallel slits. Some of the light passes through the slits,
whereupon it strikes another screen.
Light can be thought of as a kind of wave, and when waves emerge from two slits
like this they can interfere with each other. If their peaks coincide, they reinforce
each other, whereas if a peak and a trough coincide, they cancel out. This wave
interference is called diffraction, and it produces a series of alternating bright and
dark stripes on the back screen, where the light waves are either reinforced or
cancelled out.
This experiment was understood to be a characteristic of wave behaviour over 200
years ago, well before quantum theory existed.
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Document Summary
The american physicist richard feynman said this about the notorious puzzles and paradoxes of quantum mechanics, the theory physicists use to describe the tiniest objects in the universe. But he might as well have been talking about the equally knotty problem of consciousness. Some scientists think we already understand what consciousness is, or that it is a mere illusion. But many others feel we have not grasped where consciousness comes from at all. The perennial puzzle of consciousness has even led some researchers to invoke quantum physics to explain it. That notion has always been met with skepticism, which is not surprising: it does not sound wise to explain one mystery with another. But such ideas are not obviously absurd, and neither are they arbitrary. For one thing, the mind seemed, to the great discomfort of physicists, to force its way into early quantum theory.
