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Absolutely agree! Wouldn't have dove into the article without your comment. Thanks! Does anyone know if there have been experiments confirming that light's ang

by gibolt 6y ago

Absolutely agree! Wouldn't have dove into the article without your comment. Thanks! Does anyone know if there have been experiments confirming that light's angular momentum can be transferred like its linear momentum? Perhaps firing a rotating beam at a tiny sheet in space to induce spin and then reverse the light spin and confirm that the sheet eventually reverses. Since this technique could induce some extreme spin over long time/distance, I could imagine using it to pull crazy maneuvers in space. For example, aim a tiny slightly off balance disc at a distant planet. Once it started entering the planet's atmosphere, a correct entry angle and spin could take it from being head on to entering orbit.

thatcherc 6y ago
There are experiments like this! One is where circularly polarized light is used to spin up a small piece of glass to really high angular velocity (billions of rotations per second!) [1]. There are also atomic transition selection rules that depend photons transferring angular momentum into or out of an atom electronic orbitals. Essentially, when an electron jumps between the orbitals (s, p, d, etc from chemistry class), it can gain or lose angular momentum depending on its start and end state. But that momentum must be conserved, so in these cases a photon is emitted or absorbed to account for that angular momentum. The topic is kind of addressed here [2], but I'd have to dig up my old AMO notes to find a better reference. Lots of cool physics to dive into here if you're interested! [1] - https://phys.org/news/2018-07-world-fastest-rotation.html https://phys.org/news/2018-07-world-fastest-rotation.html [2] - https://en.wikipedia.org/wiki/Angular_momentum_coupling#Term_symbols https://en.wikipedia.org/wiki/Angular_momentum_coupling#Term...
raziel2701 6y ago
Yeah you can change the magnetization direction of materials by irradiating with circularly polarized light. Synchrotrons use circularly polarized x-rays to probe magnetic materials routinely. The underlying mechanism of these effects is simply the transfer of angular momentum.

by gibolt 6y ago

thatcherc 6y ago

There are experiments like this! One is where circularly polarized light is used to spin up a small piece of glass to really high angular velocity (billions of rotations per second!) [1]. There are also atomic transition selection rules that depend photons transferring angular momentum into or out of an atom electronic orbitals. Essentially, when an electron jumps between the orbitals (s, p, d, etc from chemistry class), it can gain or lose angular momentum depending on its start and end state. But that momentum must be conserved, so in these cases a photon is emitted or absorbed to account for that angular momentum. The topic is kind of addressed here [2], but I'd have to dig up my old AMO notes to find a better reference. Lots of cool physics to dive into here if you're interested! [1] - https://phys.org/news/2018-07-world-fastest-rotation.html https://phys.org/news/2018-07-world-fastest-rotation.html [2] - https://en.wikipedia.org/wiki/Angular_momentum_coupling#Term_symbols https://en.wikipedia.org/wiki/Angular_momentum_coupling#Term...

raziel2701 6y ago

Yeah you can change the magnetization direction of materials by irradiating with circularly polarized light. Synchrotrons use circularly polarized x-rays to probe magnetic materials routinely. The underlying mechanism of these effects is simply the transfer of angular momentum.