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I am not a physicist, but I am very much into popular science, especially string theory. I would like to know if it is conceivable that string theory might be able to get rid of the randomness apparent in quantum processes.

For example, radioactive decay, could this process be related to the particular phases of the vibrations of the strings composing the particle? Can it be that decay occurs when a certain constructive interference occurs between the strings?

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    $\begingroup$ Do you know that string theory is a quantum theory? $\endgroup$ – Qmechanic Dec 18 '14 at 8:36
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    $\begingroup$ String theory is a special case of quantum theory. It follows the same rules as any other quantum mechanical model. In general, quantum mechanics has very little to do with "randomness". The evolution of quantum states is perfectly continuous. It's only when we do a measurement, that the state of the system is reduced to an eigenvalue of our measurement operator. It is easy to mistake this uncertainty for randomness, but it is logically and mathematically very different. $\endgroup$ – CuriousOne Dec 18 '14 at 8:39
  • $\begingroup$ @Qmechanic - No I was not aware of that, perhaps only vaguely, I will remember that now :) $\endgroup$ – Aviad P. Dec 18 '14 at 9:30
  • $\begingroup$ @CuriousOne - Can my question then apply to the possibility to determine exactly which eigenvalue will arise? $\endgroup$ – Aviad P. Dec 18 '14 at 9:31
  • $\begingroup$ No. That's the whole point why we need quantum mechanics. We can not predict which of the possible outcomes a single measurement will have. This seems to be a fundamental limit, not just a shortcoming of our knowledge. $\endgroup$ – CuriousOne Dec 18 '14 at 9:38
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No, it's not possible. The reason is that string theory is a quantum theory. That means it includes all of the properties of quantum theory among its basic assumptions. That includes the Born rule, which relates wavefunctions to stochastic probabilities ("randomness") when measurements are made. Because string theory includes quantum randomness as an assumption, it can never hope to explain it.

This is true of almost all theories in modern physics. Quantum mechanics is seen as so basic and fundamental that it needs no explanation.

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  • $\begingroup$ What about the deterministic interpretations of quantum mechanics? Are they still compatible with string theory? $\endgroup$ – Squirtle Mar 24 '18 at 2:23
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    $\begingroup$ @Squirtle I don't know enough about string theory to definitively answer that question. But if they are, it would be the deterministic interpretation of quantum mechanics getting rid of the randomness, rather than string theory. $\endgroup$ – Nathaniel Mar 24 '18 at 2:32
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Radioactivity is a result of unstable atoms. That is, an atom that either has too many protons, neutrons or electrons to stay stable.

Using Quantum Mechanics and looking at the overlap of wavefunctions in time, it should be possible to predict the rate of radioactive decay.

But I believe you and I would be long dead before today's computers would finish a calculation like that.

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  • $\begingroup$ Does this also apply to proton decay? I'm no expert but isn't it a bit less complex in this case? $\endgroup$ – Aviad P. Dec 18 '14 at 9:07
  • $\begingroup$ Proton decay would be from the nucleus. You would have the addition of the strong force to consider in the Hamiltonian. Some symmetry may be present which you could exploit. $\endgroup$ – Michael Dec 18 '14 at 9:14
  • $\begingroup$ It's not as hard as you think it is. See e.g. ias.ac.in/pramana/v67/p363/fulltext.pdf Beta decay rates for nuclei with 115 < A < 140 for r-process nucleosynthesis KAMALES KAR1 , SOUMYA CHAKRAVARTI2,∗ and V R MANFREDI3) $\endgroup$ – CuriousOne Dec 18 '14 at 9:34

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