
Alan Harrison replied to the topic Thinking about QM as a variational principle (online 7/9 @ 9am UTC6) in the forum Timesymmetric theories 4 years, 3 months ago
One nice thing about a smooth transition between the states measured at two different times is that it looks the same for both directions of time–in keeping with the “TimeSymmetric Theories” theme.

Alan Harrison replied to the topic Thinking about QM as a variational principle (online 7/9 @ 9am UTC6) in the forum Timesymmetric theories 4 years, 3 months ago
Actually, upon reconsidering what I just wrote, it occurs to me that weak measurements may actually give some information about what happens between the two “strong” measurements at t1 and t2, contrary to what I just said. I’m not certain that that’s the case–I’ll have to think more about weak measurements–but if it is, then the following items…[Read more]

Alan Harrison replied to the topic Thinking about QM as a variational principle (online 7/9 @ 9am UTC6) in the forum Timesymmetric theories 4 years, 3 months ago
Well, I don’t think so, but if I’ve misunderstood something I’d appreciate your enlightening me. The point is that if I make a measurement (or prepare a state) at time t1 and again at t2 > t1, with no intervening measurement, then I have no experimental evidence for *how* the system got into the state I observe at t2. The Copenhagen inter…[Read more]

Alan Harrison posted a new activity comment 4 years, 3 months ago
Well, I don’t think so, but if I’ve misunderstood something I’d appreciate your enlightening me. The point is that if I make a measurement (or prepare a state) at time t1 and again at t2 > t1, with no intervening measurement, then I have no experimental evidence for *how* the system got into the state I observe at t2. The Copenhagen interpretation…[Read more]

Alan Harrison replied to the topic Possibilist Transactional Interpretation in the forum Timesymmetric theories 4 years, 3 months ago
Hello Ruth et al.,
Another way to answer Michael’s question, which I believe is equivalent to Ruth’s answer, is that not everything that is real is observable. The obvious example (from a realist perspective) is the wavefunction itself.

Alan Harrison replied to the topic Thinking about QM as a variational principle (online 7/9 @ 9am UTC6) in the forum Timesymmetric theories 4 years, 3 months ago
Hi Ken,
I had originally been trying to devise a variational principle (VP) with the desired characteristics essentially as a mathematical exercise, deferring the question of how to justify it physically. The Lagrangian viewpoint tells me that I should use the extremization of the action as my VP, so my current approach is to start with a given…[Read more]

Alan Harrison started the topic Thinking about QM as a variational principle (online 7/9 @ 9am UTC6) in the forum Timesymmetric theories 4 years, 3 months ago
I have been thinking for some years about foundational issues, with the (rather contrarian) viewpoint that what is needed is not a new interpretation of existing theory, but a new theory, expressible for instance as a modified wave equation replacing the Schrodinger or Dirac equation. The approach that appeals to me is that of a variational…[Read more]

Alan Harrison changed their profile picture 4 years, 3 months ago
