Measure the Soft with the Soft

Chris Less, with Ars Technica, recently wrote about a Physical Review Letters publication regarding a curious discovery. It appears that weakly measuring photon (light) properties amplifies those properties. The amplification happens even to the quantum domain, where the photon’s effects in all of its possibilities are amplified & detected in the measurement. So if the photon has some chance of doing A, B, and C, the weakly-measured photon will seem to more strongly do A, B, and C. Whereas a strongly-measured photo will no-so-evidently do A, B, and C - and, in fact, if the spreads of A B C are 74% 10% 16% then the strong measurement may only show the A effects.   Politely, but in the interest of improvement: I found Lee’s summary rife with poorly constructed metaphors. I respect Chris for being a dedicate writer, but the poorly-ordered metaphors made what’s happening here even harder to understand. Here’s the opening (abstract) paragraph from the original journal article:

“We show that weak measurement can be used to ‘‘amplify’’ optical nonlinearities at the single-photon level, such that the effect of one properly postselected photon on a classical beam may be as large as that of many unpostselected photons. We find that ‘‘weak-value amplification’’ offers a marked improvement in the signal-to-noise ratio in the presence of technical noise with long correlation times. Unlike previous weak-measurement experiments, our proposed scheme has no classical equivalent”

The mechanics of how weak measures grant improved resolution are the next cookie for scientists. If you try to write an article using metaphors to describe the ‘how’ then you better be doing to work of science. Any less confuses the lay readers. I respect, so much, the work to simply the original article. I’ve read it and it’s non-trivial. But way more was added in this Ars article that is ancillary to the issue here, presumably because that’s was sells in a populist column.   Apart from the metaphorical matter; I think what this represents - about the measurement of physical laws - is that our instruments need revised with an improved understanding of this scale of forces. Perhaps an apt metaphor is that we’ve used Newtonian approaches to understanding non-Newtonian scales - because we thought it should all be approximately the same. Certainly, in the 19th century and before, no real grasp existed over how these smaller orders operated. All they could do was look with the same mental Filters. Inadvertently I’ve created an opportunity to mention that I’ve edited a book on this area of the foundations of science, called Filters and Reflections.


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