We read and hear everywhere in conferences that QM is time reversible, but even for us laymen, the collapse of the wave function seems quite irreversible. It is also the case for interactions : if we take for example the e- + e+ -> ph + ph ; if you reverse the time the result will not be the initial state of the system since 1) the photons may not interact at all, 2) the result of the interaction may be a different type of particles, 3) the electron/positron pair will be ejected in a different direction.
It seems to me that the laws of QM that are time reversible are all statistical, but their realizations are in practice not time reversible, neither in fact deterministic.
Prof. Christian Thom
You can look at the following article:
Article The criterion for time symmetry of probabilistic theories an...
Your statement that is a statistical claim seems to be true, the time invariance was introduced mainly because of the spin-statistics. Probably a good look into a QED textbook could have a better understanding of the issue.
Chronologically, time reversal in QM was proposed by Prof. E. Wigner in 1932, then in the 50s with the effort of Profs. J. Schwinger, G. Lüders, and W. Pauli, it became clear that time-reversal (T) in QED is naturally considered in combination with charge conjugation (C) and spatial reflection (P), & is called in QED as a CPT-invariant.
Best Regards.
Since energy in quantum mechanics is defined as the phase factor exp(–iEt) that one gets when one moves forward in time, the way to reverse time while preserving the sign of the energy is to also reverse the sense of "i", so that the sense of phases is reversed.
https://en.m.wikipedia.org › wiki
T-symmetry - Wikipedia
https://www.quora.com/Is-quantum-mechanics-time-reversible,kindly check this link.
https://phys.org/news/2020-08-time-reversal-unknown-quantum-state.html,u can follow this link.
https://physics.stackexchange.com/questions/359799/why-is-quantum-mechanics-reversible,this link may be useful.
Cristian
If you look at Schrodinger, it only holds for energy conserving situations.
If you look at the measurement problem, then maybe irreversible is involved.
Book by Penrose sort of discusses this. After each measurement you have to start over with Schrodinger.
Regards, Juan
Thank you all for your help. I will look into the info you provided and maybe react after that.
A physical system is time reversal invariant if its underlying laws are not sensitive to the direction of time. ... There are various accounts of time reversal transformation resulting in different views on whether or not a given theory in physics is time reversal invariant. https://arxiv.org/abs/1802.10169
It had previously shown that while time-reversibility is exponentially improbable in a natural environment—it is possible to design an algorithm to artificially reverse a time arrow to a known or given state within an IBM quantum computer. https://phys.org/news/2020-08-time-reversal-unknown-quantum-state.html
Yesterday new experiments with quantum superposition of forward and backward in time were published.
https://www.nature.com/articles/s42005-021-00759-1
https://www.derstandard.at/story/2000131469290/verrueckte-quantenwelt-wenn-die-zeit-zugleichvorwaerts-und-rueckwaerts-fliesst
Regards,
Joachim
Check on this paper
https://fys.kuleuven.be/itf/staff/christ/files/pdf/pub/2005/irreversible-v5.pdf
I see from your references that the question is in fact still active among physicists, even from some very subtle points of view. But I would like to refocus my question on the topic of conservation of information : the law of conservation of quantum information seems firmly established (see the black hole information paradox), but I can't see how it can stand against the manifest irreversibility of interactions.
Aleksey Ilyin scattering is not the only case; many interactions lead to situations where symmetries (spatial or others) have to be broken : ie when particle pairs are produced, the direction in which they are emitted has generally a random component, making it not only irreversible but also not deterministic.
There should be more researches conducted to get a finte conclusion in this regard.
https://thequantuminsider.com/2020/05/18/the-importance-of-uncomputation-is-quantum-mechanics-reversible/#:~:text=Quantum%20Mechanics%20is%20reversible%20and,state%20given%20a%20particular%20Hamiltonian.
Not always time reversible . In particle physics CPT holds, not T alone.
When there is a magnetic field, reversing the direction of motion will not lead you along the same path, Not Classically nor quantum. No T reversal.
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