Thursday, June 21, 2012

The Socrates cave allegory

A core principle of quantum mechanics is the idea that observations require projections to a lower dimension. I believe that this idea is at the root of many quantum confusions.

The idea was described by the ancient Greek philosopher Socrates in about 400 BC, and written by Plato as the Allegory of the Cave. People in the cave see shadows, and do not appreciate the 3-D nature of the objects causing the shadows. They are seeing a 2-D projection of 3-D objects.

A photograph is also a 2-D projection of a 3-D scene. A measurement with a meter stick is a 1-D projection. Other observations can also be viewed as projections of some more complex reality.

Quantum mechanics is the first theory to truly take the cave allegory seriously. It has a theory for how observations correspond to projections, without ever trying to explain what is outside the cave. The theory concocts representations of reality, but is never sure about what the reality is.

Much of the confusion about quantum mechanics occurs when people try to ask about what the theory says about reality. It does not directly say anything about reality. It describes projections of that reality into subspaces, and predicts observations.

1 comment:

  1. Yes, I've been thinking about this analogy and it works for me. If you don't mind me saying so, it's a pity you aren't intending to write a book on quantum mechanics.

    Too many science writers just want to big up the mysterious aspect instead of simply telling it as it is. I'm sure many people are like me, who merely want to know what quantum physicists have actually achieved as opposed to the speculative stuff.