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- What is it and why should it apply to qm?

I've bumped into a few interesting papers talking about time-reversal symmetry in QM (eg: https://arxiv.org/abs/1507.07745) but I can't seem to wrap my head around the concept.

1) What does it mean for one to say that standard QM isn't time-reversal symmetric? Does this have to do with the "collapse" post-measurement?

2) Why should we look for quantum theory that is time-reversal symmetric? Are the reasons empirical or theoretical?

Regarding 2), I found a passage on wikipedia that says: "In other words, time is said to be non-symmetric, or asymmetric, except for special equilibrium states when the second law of thermodynamics predicts the time symmetry to hold. However, quantum noninvasive measurements are predicted to violate time symmetry even in equilibrium, contrary to their classical counterparts,". Does this mean that these theorists are looking to modify QM such that time symmetry holds for these "equilibrium states"? The paper I cited, on the other hand, doesn't say anything about such equilibrium states.

Thanks in advance!

Edit: What role does an anti-unitary operator have to play in all this?

1) What does it mean for one to say that standard QM isn't time-reversal symmetric? Does this have to do with the "collapse" post-measurement?

2) Why should we look for quantum theory that is time-reversal symmetric? Are the reasons empirical or theoretical?

Regarding 2), I found a passage on wikipedia that says: "In other words, time is said to be non-symmetric, or asymmetric, except for special equilibrium states when the second law of thermodynamics predicts the time symmetry to hold. However, quantum noninvasive measurements are predicted to violate time symmetry even in equilibrium, contrary to their classical counterparts,". Does this mean that these theorists are looking to modify QM such that time symmetry holds for these "equilibrium states"? The paper I cited, on the other hand, doesn't say anything about such equilibrium states.

Thanks in advance!

Edit: What role does an anti-unitary operator have to play in all this?

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