Wikipedia:Reference desk/Archives/Science/2024 February 8

= February 8 =

How good could rayguns be at demolition if the possibly intractable problems were trivial?
Like if you pick the particle type, flux, beamwidth (at least .010 or .001 caliber) and energy per particle right then could a (probably impossibly low waste-heat) man-portable or even pistol-like photon beam or particle accelerator (that could convert much of its mass to beam) demolish as much stuff per second as a dude throwing grenades? Is there a beam that won't dump too much energy into the air, can cause tactical nuke-level damage a few kilometers away in 3 seconds and yet not kill the user before he can finish? Preferably you'd not want to harm the user more than current common infantry weapons (maybe trading less naked ear hearing loss for more radiation bouncing back?) or have too much recoil to aim well, what would be possible with that restriction? Would neutrons be better or worse than photons or charged particles? (I don't know if neutron accelerators are even possible) Sagittarian Milky Way (talk) 00:16, 8 February 2024 (UTC)


 * Particle accelerators as conventionally defined cannot accelerate neutrons, as they work by applying an electric field to a charged particle. You can't accelerate something with no charge using an electric field.
 * The way neutrons are generated for research is fascinating - check our article on Neutron sources.
 * As far as the rest of it goes, given the amount of heavy power infrastructure attached to even small medical accelerators, the idea of something man-portable seems unlikely. PianoDan (talk) 00:23, 8 February 2024 (UTC)
 * I know, I was just wondering how powerful a theoretical particle (including photons) black box could be before you'd be too close to target and/or beam and what kind of particle is that. Obviously there could be orders of magnitude destructiveness difference between "OSHA-compliant" and "not possible even as a suicide attack (unless you can make it hold down the trigger after you're dead or something like that)". Sagittarian Milky Way (talk) 00:36, 8 February 2024 (UTC)
 * If there was such a thing, then why is not in use by armies? Probably a small rocket propelled tiny tactical nuke could do what you say. But that is a big particle. Or fire antimatter bullets or pellets at the target. Otherwise generating beams from a portable device would have to be extremely efficient, not to overheat the user, and impart all energy to the target. So it is not feasible. Graeme Bartlett (talk) 12:36, 8 February 2024 (UTC)
 * Yes but many cool science-fiction things can already be done with a different current tech. Like the Independence Day city ray. I'm not sure if antimatter bullets would not cause user damage either as air is matter. Even if you had a force field to delay matter contact till leaving the barrel. I am not sure what kind of particle beam (including different kinds of photons) has the highest ratio of impart energy to target to impart energy to air between raygun and target and would like to know. Also some kinds of impart energy to air are worse then others, i.e. X amount of energy as ionizing radiation or boom sound is worse than the same amount as heat. Sagittarian Milky Way (talk) 18:00, 9 February 2024 (UTC)
 * You want something like this but beefed up and stuck in a gun? There's far better weapons already for everything you say, a rocket is needed for the three seconds and nuke business but really you don't want that sort of energy being produced in something you hold!  NadVolum (talk) 13:16, 8 February 2024 (UTC)
 * There's a reason that the atomic hand grenade has never caught on. {The poster formerly known as 87.81.230.195} 90.199.107.217 (talk) 06:08, 9 February 2024 (UTC)
 * Also it wouldn't fit in a hand grenade. Lots of suicide terrorists would be willing to use them though if they could get them. There is an atomic grenade launcher at the limit of feasible though. Would not meet OSHA regulations on blast nearness and recoil. Sagittarian Milky Way (talk) 18:05, 9 February 2024 (UTC)
 * Possibly you missed the fact that I was making a joke [ clue: small type ], the point of which was that, assuming one could make an atomic device that small, one would of course not be able to throw it far enough to avoid being killed by its detonation.
 * Grenades are battlefield weapons: a suicide mission would not require a device small enough to be throwable, one would merely carry a suitcase bomb to the target.
 * Fortunately, construction of such devices is probably beyond the capabilities of most terrorist organisations, but there remain the possibilities of a rogue state supplying them with one, one being stolen from a state's arsenal, or the alternative of a small dirty bomb which would be less immediately destructive but possibly even more effective in the longer term. {The poster formerly known as 87.81.230.195} 90.199.107.217 (talk) 03:37, 10 February 2024 (UTC)
 * There was a Davy Crockett (nuclear device) really inconvenient for one person but much less so than any chemical energy way of carrying 20 tons of TNT equivalent. 1.25 mile range. Sagittarian Milky Way (talk) 04:20, 11 February 2024 (UTC)
 * If the problems of making rayguns with excellent demolition capabilities were trivial, only trivial problems stand in the way to make rayguns with excellent demolition capabilities. Assuming we can overcome these trivial problems – which is a reasonable assumption, since otherwise the problems are nontrivial – the inevitable conclusion is that the rayguns could be very good, nay, indeed excellent, at demolition. I hope this answers the question conclusively. --Lambiam 14:43, 12 February 2024 (UTC)
 * Yes but if the beam follows the laws of physics starting at the muzzle and so does any protection (goggles? earplugs and earmuffs? lead-backed volcanology suit?) then it becomes more and more annoying to use the higher the power (for any given beam specification, target distance etc), eventually it either kills you almost instantly or has so much recoil you can't aim or stand up. I'm wondering what's the most damaging kind of beam a human could hold (not necessarily most watts as neutrinos may or may not have a good enough damage to miles away to damage to user ratio, at the extreme fluxes that damagr even user regardless of target range (through Earth's atmosphere, line-of-sight surface-to-surface)). Maybe a good particle is a specific kind of photon with sufficiently long mean free path for interaction with dinitrogen, dioxygen, argon and as many other common air substances and pollutants as possible while having a good interaction mean free path in as many common target substances as air transparency allows? Also a low percent of energy reflecting or scattering from target or its vaporization cloud, and low vaporization cloud shielding. An issue with publicly known lasers is they're slower than if the cloud of vaporized surface was transparent to that wavelength of infrared. Sagittarian Milky Way (talk) 17:09, 12 February 2024 (UTC)
 * As Lambian pointed out, those issues are solved "trivially" by definition, in this constructive argument that has been left as an exercise to the reader. Don't make him provide an example, because these premises are so universally well-known, we can't even remember who came up with it.  Because it's a ray-gun. Nimur (talk) 17:50, 16 February 2024 (UTC)