- This article in ars technica is about this paper, in which a quantum interference experiment is performed that, in the most straightforward interpretation, involves superpositions of states where "event A preceded event B" and "event B preceded event A". This is in the same mind-zapping vein as quantum eraser experiments. I haven't read this in detail, but my typical takeaway from these things is two-fold: (1) the math of the usual quantum mechanics formalism is in excellent agreement with experiment every time it's been checked, and (2) nature doesn't care about our hang-ups about interpretation, especially when phrasing questions about quantum in terms of, "what classical past history should have happened here, when we weren't actually making observations?"
- This paper in Advanced Materials is a very nice overview about application-relevant magnetic materials (e.g., rare-earth magnets like Nd2Fe14B) and where we might want to look to find new ones.
- This youtube video is a great discussion and experimental proof of the Feynman inverse sprinkler problem. The short version: suppose an ordinary water sprinkler rotates clockwise when it's spewing water out of its arms, the momentum flux of the water generating a torque. If instead you immersed the sprinkler in water and had suction bring water in through the arms, which way would it spin, if it spins at all? I don't want to spoil it for you. Watch the video - it's very nicely done.
- I'm not sure the link will work for everyone, but there is an article in The Atlantic called "The Shocking Speed of China's Scientific Rise". For anyone paying the slightest bit of attention for the last decade, this must be some new definition of "shocking" with which I was previously unfamiliar.
- Info is beginning to trickle out about the likely presidential budget request for FY27, and guess what: some of the same folks who freak out that China might surpass the US as a science power are again going to pitch big budget cuts (article is about NIH, but it's hard to imagine other agencies won't be similarly viewed). Congress largely pushed back against the PBR this past year, but this is an annual exercise in the US - it never stops.
Sunday, March 29, 2026
Brief science items and news
As I distract myself from work-related writing that I really need to do, here are a few science-related links:
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2 comments:
"(1) the math of the usual quantum mechanics formalism is in excellent agreement with experiment every time it's been checked" Yes.
"(2) nature doesn't care about our hang-ups about interpretation"
Also yes, but I would add that nature cares what experiments we choose to build and how we build them (which depend on intuitions associated with interpretation) but doesn't care how we describe an experiment after we have built it.
Classical physics cannot describe some results of some experiments because of the various no-go theorems, which I take to say that *classical physics is incomplete*. We can just say "and that's it", or we can ask what we can add to classical physics to make it as complete as quantum physics. We can easily add A) noncommutativity, by using the full power of the Poisson bracket; and B) 'quantum noise' as well as 'thermal noise', with the difference being invariance of quantum noise under an action of the Lorentz group.
I develop this in an approach as close to experiment as a theorist can go by focusing on signal analysis as a way to think about quantum mechanics in Annals of Physics 2020, "An algebraic approach to Koopman classical mechanics", https://arxiv.org/abs/1901.00526 (DOI there.) Given that we can describe an experiment either using QM or using what I call CM+, we do not have to say that systems are 'quantum' or 'classical', which is a kind of unification that over the next few decades will become second nature.
China produced more inventions and discoveries than Europe until 1600 or so (the compass, gunpowder, and paper being some of the biggest). We are returning to the status quo…
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