Heisenberg's Uncertainty Principle (reject, verse, science, Article)

[Fluffy]

Due to my interest in the nature and possible existence of free will, I have found an increasing portion of my time is taken up in studying this principle. However, whilst I believe I have a good understanding of what Heisenberg's uncertainty principle is and the evidence for it, I am very confused about its implications.

Apparently, the majority of physicists agree with what is known as the Copenhagen interpretation meaning that not only are certain things unmeasurable with 100% accuracy (and therefore unpredictable) but also that this undermines cause and effect. In other words, it advances what was once an apparent boundry in human knowledge into the replacement of determinism with probalism.

Unfortunately, I have been unable to understand the logic and science behind this extra conclusion. The main players who rejected the Copenhagen interpretation seem to have done so simply because they rejected the uncertainty principle in its entirety, such as Einstein and Lande, and this is unacceptable to me. The mere fact that the interpretation has so many proponents adds a lot of weight to it in my mind and so I am wondering if anybody could offer a clear explanation of the groundings of the Copenhagen interpretation.

[michel]

Originally Posted by Fluffy

Due to my interest in the nature and possible existence of free will, I have found an increasing portion of my time is taken up in studying this principle. However, whilst I believe I have a good understanding of what Heisenberg's uncertainty principle is and the evidence for it, I am very confused about its implications.

Apparently, the majority of physicists agree with what is known as the Copenhagen interpretation meaning that not only are certain things unmeasurable with 100% accuracy (and therefore unpredictable) but also that this undermines cause and effect. In other words, it advances what was once an apparent boundry in human knowledge into the replacement of determinism with probalism.

Unfortunately, I have been unable to understand the logic and science behind this extra conclusion. The main players who rejected the Copenhagen interpretation seem to have done so simply because they rejected the uncertainty principle in its entirety, such as Einstein and Lande, and this is unacceptable to me. The mere fact that the interpretation has so many proponents adds a lot of weight to it in my mind and so I am wondering if anybody could offer a clear explanation of the groundings of the Copenhagen interpretation.

I doubted that I could offer any help; having seen this:-
http://zebu.uoregon.edu/~imamura/208/jan27/hup.html

If there is a particle, such as an electron, moving through space, I can characterize its motion by telling you where it is (its position) and what its velocity is (more precisely, its momentum).

• Classically, that is, in our macroscopic world, I could, in principle, measure the position and momentum of the object to infinite precision (more or less). There is really no question about a particle's position and momentum.
• In the Quantum Mechanical world, the idea that we can locate objects exactly breaks down. Let me state this idea more precisely. Suppose a particle has momemtum p and position x. In a Quantum Mechanical world, I would not be able to measure p and x precisely. There would be an uncertainty associated with each measurement that I could never get rid of, even in a perfect experiment!!! The size of the uncertainties are not independent; they are related as
  
  dp x dx > h / (2 x pi) = Planck's constant / (2 x pi)
  The preceding is a statement of the Heisenberg Uncertainty Principle. A consequence of the Uncertainty Principle is that if an object's position x is defined precisely then the momentum of the object will be only weakly constrained, and vice versa. One cannot simultaneously find both the position and momentum of an object to arbitrary accuracy.

I know I haven't a hope.

[Fluffy]

We do not know if this indeterminism is actually the way the Universe works, because the theory of Quantum Mechanics is probably incomplete. That is, we do not know if the Universe actually behaves in a probabilistic manner (there are many possible paths a particle can follow and the observed path is chosen probabilistically) or if the Universe is deterministic in the sense that I could predict the path a particle will follow with 100 % certainty.

Thanks for the article Michel, this paragraph is from it and helps explain what I am after much better than I did.

The Copenhagen interpretation takes the stance that the universe is probalistic but as this article states, and I must agree, this is only one possibility. However, this does go some way to clear up the problem I have been having. Perhaps the uncertainty principle on its own does not actually give any support to the Copenhagen interpretation, it merely opens up the possibility of a probalistic universe, a possibility that had previously been closed. The Copenhagen interpretation takes advantage of this possibility but is actually supported by other evidence independent of Heisenberg's earlier work. Does anybody know if I am correct in thinking this?

[michel]

Originally Posted by Fluffy

Thanks for the article Michel, this paragraph is from it and helps explain what I am after much better than I did.

The Copenhagen interpretation takes the stance that the universe is probalistic but as this article states, and I must agree, this is only one possibility. However, this does go some way to clear up the problem I have been having. Perhaps the uncertainty principle on its own does not actually give any support to the Copenhagen interpretation, it merely opens up the possibility of a probalistic universe, a possibility that had previously been closed. The Copenhagen interpretation takes advantage of this possibility but is actually supported by other evidence independent of Heisenberg's earlier work. Does anybody know if I am correct in thinking this?

I have a headach; do you mean that the intention was to prove probablility, that there is now an 'error margin' to show that there can be deviation from that ?

[Fluffy]

I have a headach; do you mean that the intention was to prove probablility, that there is now an 'error margin' to show that there can be deviation from that ?

Not quite. I mean that before the uncertainty principle, determinism was the accepted way of things because there was no evidence to suggest that anything other than cause and effect was going on. However, the uncertainty principle shows us a range of examples in which we cannot actually see the cause and the effect process, therefore allowing the possibility that something other than cause and effect might be at work here ie randomness.

Therefore, it might have been Heisenberg's later work that led him to develop the Copenhagen interpretation and this work was not really as dependent on the uncertainty principle as I had first assumed.

[michel]

hmmmmmmmmmmm*pretends he understands*..........oh yes, of course!

[evearael]

the uncertainty principle shows us a range of examples in which we cannot actually see the cause and the effect process, therefore allowing the possibility that something other than cause and effect might be at work here ie randomness.

The result of the two-slit experiement is hardly random.

You are asking for a book or two (don't worry these are accessible to the non-physicist ):
Schrodinger's Cat and the Search for Reality
Schrodinger's Kittens
If you finish these and would like more, let me know. How much math have you had?

[angellous_evangellous]

Originally Posted by evearael

The result of the two-slit experiement is hardly random.

You are asking for a book or two (don't worry these are accessible to the non-physicist ):
Schrodinger's Cat and the Search for Reality
Schrodinger's Kittens
If you finish these and would like more, let me know. How much math have you had?

Also read Hawkins... he will cleanse your mind from irrational conclusions drawn from both interpretations and misinterpretations of Schrodinger.