Time symmetric quantum mechanics

the_pulp

I have been asking during the last couple of days about EPR, measurement problem and all those sort of things. As a consequence I arrived to this funny interpretation in which (as wikipedia says) locality, determinism and a lot of desirable (to me) properties are preserved. Nevertheless I saw in diferent threads that this interpretation has not a lot of supporters. Why is it? Because it violates causality? (from my ignorant point of view, since every law in physics -including 2nd law of thermodinamics as it is explained by fluctuation theorems- may be time reversed, causality is something that should be demostrated or disprobed -this 2nd view is the adopted by TSQM-)

What do you think about this interpretation? Why?

Thanks

PS: This thread does not admit ShutUpAndCalculate supporters (hahaha)

DrChinese

Good interpretation, I think very useful. I wouldn't necessarily agree that determinism is maintained, however. I am not aware of any elements which explains why collapse leads to a particular observed value. After all, the results are random and still not explained by future events.

the_pulp

I like to think that the particular result is obtained in the interaction of the system with the instrument being used to measure. I tend to think that the instrument has internal degrees of freedom not known by the scientist (zillons of degrees of freedom) and that these ignorance make the result random (in the view of the scientist) but in fact, behind that ignorance, it is truely deterministic. And, moreover, if the randomness is such that the result does not depend on the distribution of possible quantum states of the instrument, but only on the initial state of the system under measurement, then, by some theorems (Gleason, Saunders, whatever) the only distribution possible is the one that emerges by born rule.

For the record, the whole previous paragraph is my humble and, perhaps, ignorant addition to TSQM (I mentioned it because you said that you dont know any mecanism through which this interpretation can be coherent with determinism in the result and I think that what I say is such a mecanism -if the scientist knows the exact initial state of the instrument, he sees no randomness-). Am I right???? If not, what am I not seeing???

Thanks for your answer

DrChinese

Well, I wouldn't exactly call that a mechanism. You still have (apparent) randomness, and there is no explanation of how any "degree of freedom" determines the result. Most of the TS interpretations consider themselves indeterministic.