Why is Psi^2 not square rooted in Schroedinger's Equation?

[unusualname]

Doesn't QM make make evolution a mirage?

eh?

Of course, the more sane veiw is that free-will is illusory, even if we have fundamental randomness in QM, since it seems more likely that evolution only works at molecular granularity and at best we may able to "reshape" the wave-function in some limited ways, but since that would have to obey Schrodinger evolution it would be a deterministic mechanism, even if the actual wave-function "collapse" is random. Then we're just like flotsam floating on an ocean, the future is undecided (no superdeterminism) but we can't really choose where it leads.

 

[sujiwun]

eh?

.

I wasn't suggesting that evolution doesn't exist, just that the order we see and call evolution is the product of randomness. That doesn't mean it is random - it still has the same structure we call evolution, the same order - just that its driving mechanism, is randomness, chaos.

In otherwords, "the fit survive" may be true in general - as part of the perceived order, nevertheless, just because you are fit it doesn't necessarily follow that you will - as part of the random chaos - you might still get hit by that bus tomorrow.

The philosophical implications as it relates to free will can be seen in history - fascism's "will to power" in a controlling attempt to create a race of ubermenschen vs humanistic liberalism.

 

[Demystifier]

Why not? We might just have our choices limited by what Psi allows as possible states, but still be able to choose those states when we exercise free-will, at least in some limited form.

Can a free will decide to end in the state |up> WHENEVER the wave function is |up>+|down>? If it can, then it contradicts quantum mechanics. If it cannot, then it is not free will. Does, either quantum mechanics is wrong or free will does not exist.

 

[unusualname]

Can a free will decide to end in the state |up> WHENEVER the wave function is |up>+|down>? If it can, then it contradicts quantum mechanics. It it cannot, then it is not free will. Does, either quantum mechanics is wrong or free will does not exist.

Well, QM obviously isn't the full story, just a probabilistic mathematical model that works very well.

But eventually, physics will have to tackle the problem of human free-will and consciousness, since even String/M theory isn't a Theory of Everything (doesn't even attempt to solve the QM interpretation problem)

I think most physicists expect that consciousness & free-will is akin to a phase-change, a complex emergent phenomena from essentailly simple underlying physics, and free-will is itself not subverting deterministic Schrodinger Evolution, since there doesn't seem to be a workable explanation of how the molecular granularity of Evolution could create a physical mechanism that would work sub-quantum level.

But physics doesn't even tackle the underlying randomness of QM yet, there is no agreed understanding of why QM appears random. If there is an underlying mechanism producing uncaused events, then it gives some hope that free-will may be possible. But for uncaused (nondeterministic) events the microscopic dynamics either need a singularity or boundary points where degrees of freedom suddenly increase.

There is some speculation (and some papers on arXiv) that particles themselves may be microscopic black holes, but even then the cosmic censorship hypothesis suggests naked singularities cannot form.

So for now we are stuck with a determistically evolving Psi and a random "collapse" mechanism. But we have no idea why this is so. The dBB interpretation suggests that the probabilities are simply describing an underlying deterministic dynamics, and that is appealing since we have the well-known notion of invariant measures (probability densities) in ergodic theory which can be applied.

But that just seems a little too convenient, and still leaves the huge problem of explaining the physical origin of Psi, and its non-local mechanism.

Its amazing that after 80 years we haven't progressed much on these issues.

 

[Demystifier]

Well, QM obviously isn't the full story, just a probabilistic mathematical model that works very well.

I'm fine with that. But then deterministic Bohmian version of QM may also be compatible with free will, as long as you allow that Bohmian QM, even if more correct than standard QM, is not the final theory of everything either.

My point is that, concerning the issue of free will, probabilistic and deterministic interpretations of QM are equally good (or equally bed), so one should use free-will arguments to prefer one over the other.

 

[unusualname]

I'm fine with that. But then deterministic Bohmian version of QM may also be compatible with free will, as long as you allow that Bohmian QM, even if more correct than standard QM, is not the final theory of everything either.

My point is that, concerning the issue of free will, probabilistic and deterministic interpretations of QM are equally good (or equally bed), so one should use free-will arguments to prefer one over the other.

Ok, but for (true) free-will you need non-determinism at some level of nature, Bohmian Mechanics makes it difficult (for me) to see where that non-determism can arise, since then, even if our evolved consciousness is able to "load the dice" wrt the decoherence mechanism for quantum state selection, BM still says it's a deterministic mechanism. So free-will will then require something quite novel, and currently unknown to physics, which would be frustrating, since I want to blimin' know how this all works in my lifetime.

 

[Demystifier]

Ok, but for (true) free-will you need non-determinism at some level of nature, Bohmian Mechanics makes it difficult (for me) to see where that non-determism can arise, since then, even if our evolved consciousness is able to "load the dice" wrt the decoherence mechanism for quantum state selection, BM still says it's a deterministic mechanism. So free-will will then require something quite novel, and currently unknown to physics, which would be frustrating, since I want to blimin' know how this all works in my lifetime.

It is very easy to add a non-deterministic component to Bohmian mechanics. Just modify the Bohmian velocity formula, by addding one additional stochastic velocity term the statistical average of which vanishes.

 

[unusualname]

It is very easy to add a non-deterministic component to Bohmian mechanics. Just modify the Bohmian velocity formula, by addding one additional stochastic velocity term the statistical average of which vanishes.

I suppose so, but it would then require new ideas to explain that stochastic mechanism, which might be built on another (lower) level of deterministic dynamics and so on...

(The idea of deterministic chaotic dynamics generating the probability densities is appealing is some ways, but it still implies the future is already decided even if it is unknowable (not predictable). Physics needs an non-deterministic mechanism at some level, and I don't know why singularities (for example) are considered such a bad thing.)

 

[sujiwun]

Well, QM obviously isn't the full story, just a probabilistic mathematical model that works very well.

But eventually, physics will have to tackle the problem of human free-will and consciousness, since even String/M theory isn't a Theory of Everything (doesn't even attempt to solve the QM interpretation problem)

More likely that human psychology will explain physics than vice versa.