https://www.quantamagazine.org/puzzling ... d21d14a9ea
There are problems with this article:
Problem 1.
False! The Landau-Lifschitz pseudo tenser has a divergence which expresses energy conservation cosmologically in comoving coordinates. That divergence = 0 which is the appropriate way to apply Noether's theorem to GR and energy conservation.The mathematician Emmy Noether proved in 1915 that conserved quantities like energy and momentum spring from symmetries of nature. Energy is conserved because of “time-translation symmetry”: the rule that the equations governing particles stay the same from moment to moment. (Energy is the stable quantity that represents this sameness.) Notably, energy isn’t conserved in situations where gravity warps the fabric of space-time, since this warping changes the physics in different places and times, nor is it conserved on cosmological scales, where the expansion of space introduces time-dependence. But for something like light in a box, physicists agree: Time-translation symmetry (and thus energy conservation) should hold.
Problem 2.
False! One can attach an accelerometer to the mirror and see the recoil of the gamma ray photon. Omitting the accelerometer does not make it a non measurement. The apparent energy and momentum non conservation comes from interaction with the mirror, IMO.Remember we’re dealing with the photon’s wave function here. Since the bounce doesn’t constitute a measurement, the wave function doesn’t collapse. Instead, it splits in two: Most of the wave function remains in the box, but the small, rapidly oscillating piece near where the mirror was inserted leaves the box and heads toward the detector.