notes-physics-quantum

Random ideas for things that may or may not have to do with quantum physics:

synchronization (shared memory consistency models) in computing

(although this sounds more like spacelike stuff in relativity)

market-making scale

(concerns with bid/ask spread, limit order book, small time scales, bid/ask bounce, etc) in financial markets sound 'quantum' in that you can no longer assume that individual orders merge into a statistical aggregate

in finance, kelly criterion vs expected value valuation of investment opportunities

with the Gaussian approximation of Kelly, investment opportunities are valued by expected_return/stddev^2 instead of expected_return/stddev (Sharpe). Could the square of stddev here be related to the perspective on quantum physics that it's like probability theory except that you square the magnitude of the probability amplitude instead of using it directly?

arguing in the alternative in law

think about this joke:

A neighbour accuses a lawyer that the casserole he'd given him was returned broken. They can't settle the case and so go to house of justice. "Your honour, none of this ever happened", replies the lawyer. "Please explain", says the judge. "First, This man has never given me any casserole". "Second, I've returned it all in good shape". "and third, it was already broken when he handed it to me".

now, logically, there's usually nothing wrong with arguing in the alternative; consider skeptically reading a scientific paper: "The measuring device measured level X of object Y. But maybe it wasn't actually measuring object Y. Or maybe it was measuring Y, but it was miscalibrated. Or maybe object Y had level X at that moment, but doesn't typically have level X outside of the unnatural context of that experiment.". Why do people want to reject the lawyer in the joke while accepting the reasoning here?

Because the lawyer in the joke was also playing the role of the witness. The witness, like the measuring device, is expected to report one consistent view of reality (the facts of their sensory experience). Then we can dispute the interpretation of the facts (that is, the values of hidden state variables). In the joke, it would have been okay if the defendent (the purported borrower) claimed that he never borrowed the thing; and a 3rd party witness said that the thing was borrowed but was broken beforehand; and another 3rd party witness claimed that the thing was borrowed but it was fine upon return; at least 2 of these 3 witnesses must lying but as long as any one of them is telling the truth, the defendent is innocent. The defendent's lawyer would be correct to point this out. However, if the defendent emself claims all three of these things simultaneously, then the defendent is definitely lying, which reduces their credibility and makes less likely to believe that any of their claims are true.

This interplay between keeping multiple conflicting hypotheses in mind, and the need for consistency from measurement devices, is reminiscent of quantum physics.