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October 22

Although neutrinos can't interact with photons, can photons deliver momentum to neutrinos, via electrons as intermediaries which receive it from photons and deliver it to neutrinos?

Something that reminds of Newton's cradle (yet not exactly of course). HOTmag (talk) 16:06, 22 October 2024 (UTC)[reply]

This is the kind of thing that Feynam diagrams were invented for. You can have a neutrino and a photon going in, a neutrino and a photon going out, and all kinds of other particles running around in a loop in the middle. See for example [1] (paywalled unfortunately). --Amble (talk) 17:21, 22 October 2024 (UTC)[reply]

I gotcha covered on the link there

--Slowking Man (talk) 17:32, 22 October 2024 (UTC)[reply]

Why can't they interact? Both photons and neutrinos participate in the weak interaction. Difficulty: that cross-section is gonna be really small. Gamma ray cross section may be also of interest. But yes, the aforementioned besides, if you have a whole lot of photons and can make them go where you want and give them arbitrary energies, you can make the photons do all kinds of neat tricks with each other such as popping out other particles: see two-photon physics. The truly "high-energy physics" processes in our universe such as supernovas and neutron star collisions and gamma-ray bursts do plenty of this kind of stuff. (Another whopper is that we're now fairly sure type II supernovas are in essence "powered" mostly by the neutrino burst! The core collapse releases such a staggering amount of neutrinos that, if you somehow managed to get close enough and not have anything else kill you, you would be killed by the fatal neutrino radiation! As they say there, a phrase that just looks wrong if you know what it's talking about. Similarly: an "average supernova" releases about 10⁵⁷ neutrinos, 10 followed by a mere 57 zeroes. Kind of like: a "modest planetary collision" will only disrupt the crust and some of the mantle. (And one hypothesis is, the reason half of Mars is really different from the other half is that an even bigger impact happened to it!) --Slowking Man (talk) 17:29, 22 October 2024 (UTC)[reply]

Why can't they interact? Both photons and neutrinos participate in the weak interaction It seems that your question is addressed (also) to yourself, i.e. to what you wrote in another thread. HOTmag (talk) 18:17, 22 October 2024 (UTC)[reply]

Is it true the Pacific's where the Mars-sized moonmaker hit non-head on splashing off lava and boiled lava? I thought only continental crust can survive that long. Sagittarian Milky Way (talk) 22:21, 22 October 2024 (UTC)[reply]

If so it's not mentioned at our giant-impact hypothesis article, nor the Theia (planet) one. I would have been surprised if that were true; I assumed that the Earth's entire surface was liquid for a while after the impact so there shouldn't be any remaining localized remnant. But I could be completely wrong about that. --Trovatore (talk) 22:56, 22 October 2024 (UTC)[reply]

That's where the Kaiju come from right? But seeing as >4 bil ybp, there was no such thing as "the Pacific Ocean"... I dunno? Is this based on some specific thing from somewhere? A mere 220 mya there was just the one ocean with no major landmasses apart from "the one place where all the land is". If I recall right the hypothesized Theia impact is predicted to maybe have re-liquified Earth's entire crust, even vaporizing some of it to produce a temporary "rock vapor atmosphere", another one of those "phrases that just sound crazy". (Excellent band name up for grabs there btw) --Slowking Man (talk) 23:02, 22 October 2024 (UTC)[reply]

I heard that somewhere maybe whoever thought it was just ignorant? Sagittarian Milky Way (talk) 00:20, 23 October 2024 (UTC)[reply]

we can propose sending photons "this way" and neutrinos "that way", such that their worldlines at some point intersect, but we would expect to observe nothing (other than the extremely minute effects of their gravitational and weak interactions), (emphasis added). Okay, I was being a tad pedantic, but, being precise can matter for Science Stuff. You're the one proposing hypothetical scenarious here—you could always say "here, we're gonna fire enough photons such that their weak interactions w/ matter start adding up" (like in a supernova). Alternately if you just want to ask, "can photons and neutrinos interact with each other at all, directly or indirectly" just ask that and skip the trouble of crafting undergrad physics textbook study problems. (Keep in mind, people here are volunteering to devote some of their own time to responding to questioners' queries.) --Slowking Man (talk) 23:02, 22 October 2024 (UTC)[reply]

Oh sorry, I did read what you had written in parentheses "other than the extremely minute effects of their gravitational... interactions", but for some unknown reason I didn't notice the crucial words "and weak interactions". So you're right, sorry.

As for the two-photon physics you've mentioned: Well, AFAIK, two photons can turn into electron-positron (or muon-antimuon, tauon-anti-tauon), but never (directly) into neutrino-anti-neutrino. The same it true for the opposite direction: If a neutrino collides with its anti-particle, the direct result may be Z-boson, not photons (and with regard to what you wrote in your last parentheses: Of course, indeed you are always invited to remove my misunderstanding, but are never obligated to do that). HOTmag (talk) 00:24, 23 October 2024 (UTC)[reply]

That makes my (new) list of most exotic way to shuffle off this mortal coil. Clarityfiend (talk) 00:07, 23 October 2024 (UTC)[reply]

Victim [knocking on the Pearly gates]: Hello?

St. Peter: Sorry, guy. There's no room at the inn for you. Have you tried the Other Place?

Victim: But, but I'm high up on The List!

St. Peter: That cuts no ice up here.

Victim [in desperation]: Uh, I was struck down by neutrinos!

St. Peter: Way cool, dude! Okay, I can make an exception for you. Just don't tell anyone. Clarityfiend (talk) 03:07, 23 October 2024 (UTC)[reply]