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*Post by Quadibloc**Post by Quadibloc*http://youtu.be/p8lMAvDdCqY

http://youtu.be/XzoNfNZsT0A

I posted this to sci.physics as a more appropriate place, but I really shouldn't just pun and run...

I feel that matters are such that I can no longer remain silent.

The Schroedinger Equation, on which non-relativistic quantum mechanics is based,

is linear. As a result, there is no threshold of size at which the phenomenon of

the superposition of states is predicted by it to cease to exist.

This led to the famous thought-example known as "Schroedinger's Cat".

In order to account for the fact that superposed states are not observed in our

macroscopic world, the Copenhagen Interpretation of quantum mechanics was

developed. According to this interpretation, the act of observation takes place

when phenomena are communicated to a conscious human mind, and observation is

what causes symmetry breaking, leading to a wave function associated with a

superposed state resolving to an eigenstate of the parameter being observed.

This particular YouTube video is one example of a phenomenon that has taken

place in many popular accounts of quantum theory, and in writings of a

philosophical, mystical, or religious nature that bring in quantum mechanics as

a source of evidence - evidence that science now admits that a mechanistic view

of the world is no longer valid, but instead that mind and thought are

fundamental.

These conclusions are unsupported.

The Schroedinger Equation is the equation of non-relativistic quantum mechanics.

The speed of light is, in fact, finite, and both the Special Theory of

Relativity and the General Theory of Relativity are proven by experiment. Thus,

the Schroedinger Equation is _not_ the last word on quantum mechanics: it is an

approximation.

A simple and obvious way to account for the absence of superposed states in the

macroscopic world we see is to assume that the "real" equation of quantum

mechanics is non-linear, and so more massive objects are constrained to behave

in a more classical manner than less massive ones.

However, at the moment, we do not know the nature of those nonlinearities, or

whatever other phenomenon might play a similar role. (Thus, for example, Roger

Penrose advanced a theory that the curvature of space can't be quantized, so

once gravity becomes involved, states cease to be superposed.)

Thus, until that question is resolved, to defer it until another day, the

Copenhagen Interpretation simply takes note of the ultimate boundary condition,

the place where we know that superposed states do not exist, and applies that to

the linear quantum mechanics of the Schroedinger Equation.

Thus, in my opinion at least, the proper view of the Copenhagen Interpretation

is that it is an expedient adopted to cope with our current limited

understanding of the true nature of the quantum world, and thus it is not a

statement of physical fact the way that the Schroedinger Equation itself is a

close approximation to real physical facts, and so it is not at all sound to

draw conclusions from it, even conclusions of a philosophical nature,

particularly when they are far-reaching and fundamental.

And then there's the de Broglie pilot wave theory. This doesn't even require

amending the Schroedinger Equation. It has been neglected because it tends to be

viewed as hidden variables by another name, or because, given that it doesn't

change any of the physical predictions of quantum theory, the distinction

between it and conventional quantum mechanics is one of philosophy and not

physics. Well, if incorrect philosophical conclusions are being drawn from

quantum mechanics, making a philosophical amendment to quantum mechanics is

warranted.

Today, of course, we are approaching a "theory of everything". The

renormalizable extension of Kaluza-Klein theory known as supergravity, and its

related extension known as string theory has permitted the framework of the

General Theory of Relativity to be extended to embrace electromagnetism and the

weak and strong nuclear forces.

While it is hard to visualize the curvature of space-time as being itself only

the apparent state of an underlying wave function, I believe it is an error to

assume that Nature is constrained to have ultimate laws that we can visualize,

even if I still hope that we can still attain an understanding for practical

purposes through mathematics. So I don't feel that relativity makes it necessary

that the view of Roger Penrose is correct.

But the fact that the real quantum-mechanical equations won't be simple and

linear means that there is no reason to despair and come to the conclusion that

the stopgap of the Copenhagen Interpretation will forever remain a part of

quantum mechanics.

John Savard