Why field theories are deterministic, but QM isn't?
- From: dudajar@xxxxxxxxx
- Date: Mon, 23 Mar 2009 14:35:09 -0700 (PDT)
Quantum electrodynamics (relativistic quantum field theory) is
believed to be better approximation of physics than quantum mechanics
- for example because it allows for extremely accurate predictions of
Lamb shift.
http://en.wikipedia.org/wiki/Quantum_electrodynamics
One of formulations of field theories is due to Lagrangian density -
physics finds the field which minimizes integral of this density over
four dimensional space - so called action.
Now using Euler-Lagrange equations, we can find necessity condition
for such minimization, which is in form of time evolution - we get
'evolving 3D' picture.
These equations are completely deterministic - we don't have a problem
with for example probabilities, wavefunction collapses ...
So why its predecessor which we commonly use - quantum mechanics is
completely undeterministic - we can usually talk only about
probabilities????
For me it clearly shows that QM is forgetting about something - kind
of 'subquantum noise' ... which determines quantum choices.
We cannot fully measure QM ... so it's probably even worse with this
'subquantum information'.
We can say only about probabilities of quantum choices - but in fact
they should be deterministic - they are stored somewhere there!
What we can talk about is that events have been causally connected in
the past - we call it entanglement: if two photons have been created
together we cannot know what spin they have, but we know that it's the
same one.
So from our point of view - the future will decide which of entangled
events will be chosen ... but in fact it's written in some subquantum
information, but we cannot even think about measuring it.
Bohm's interpretation uses 'pilot-wave' which goes into future to
choose how to elongate trajectory.
But maybe it would be better to use CPT conservation as in QED and try
to interpret QM fully fourdimensionally.
Now everything is clear:
- probability is proportional to the square of amplitude, because it
has to agree in both past and future halfplanes,
- knowing only the past we can predict only probabilities,
- entanglements means that events are causally connected in the past.
One of them will be chosen in the future (as in Wheeler's
experiment).
Here is expanded this topic:
http://www.advancedphysics.org/forum/showthread.php?t=11844
What do You think about it?
.
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