Wikipedia:Reference desk/Archives/Science/2023 August 23

= August 23 =

MOAB Glue in real-life?
How does a MOAB Glue from BTD6 attacks and slow down a blimp if they're flying/floating at high altitudes? And what kind of suit they're wearing (perhaps a much different version of class-D hazmat suit we see today)? 2001:448A:3070:E025:4DDB:44DD:7A7A:5571 (talk) 00:52, 23 August 2023 (UTC)


 * It works because it’s a videogame and therefore can do whatever the creators want, with no regard to real world physics or chemistry. —OuroborosCobra (talk) 01:30, 23 August 2023 (UTC)
 * @OuroborosCobra: Yeah but let's assume that it is based on science (e.g. how does a MOAB Glue wear a particular PPE suit instead of typical lowest class of hazmat suit in real-life?), and I have plenty of questions of this subject got answered on weekly NK blog posts like this one. 2001:448A:3070:E025:4DDB:44DD:7A7A:5571 (talk) 02:14, 23 August 2023 (UTC)
 * We can't really do that because, fundamentally, it's not based on anything in real science, and so can't be analyzed with the preconception of following real science. --OuroborosCobra (talk) 02:24, 23 August 2023 (UTC)


 * And if most of us aren't familiar with the video game, you may have to show us a video of it to describe what is going on. 170.76.231.162 (talk) 18:17, 23 August 2023 (UTC).
 * There is a lot to learn. Philvoids (talk) 11:35, 24 August 2023 (UTC)

Mild starlight with no UVB
As I understand, UVB radiation, despite causing potential burns and cancer, is essential for the vitamin D skin production. Under known physics, can a star emit a light that has no cancer or burn risks like UVB radiation or is it more like catch-22 where evolution restricted vitamin D production to UV radiation only? 212.180.235.46 (talk) 18:47, 23 August 2023 (UTC)
 * The Stellar spectrum of a star is usually quite close to an ideal Black-Body Radiation spectrum whose shape (i.e. the relative output at each wavelength) is determined by its surface temperature. As you will see from the graphical representations in those articles, the output of UV light from a black body or star is an appreciable fraction of its output in its (to us) visible spectrum. A star with very little UV radiation would have to be, by stellar standards, quite cool, and would likely not have sufficient output to support life on an orbiting planet.
 * The photosynthesis of Vitamin D has to operate within existing physical parameters; if it were possible to utilise light at wavelengths with less harmful effects, evolution would likely have long since achieved that (and we would all have very black skin to block the UV, so would have to invent other bases for irrational predjudices). The process of evolution performs de facto cost-benefit experiments, and will often arrive at an outcome where some degree of harm persists if it is outweighed by linked benefits, so that the population of organisms in question benefits overall.
 * it would be more feasable that a hypothetical planet could have an atmospheric composition that blocked more UV radiation than is the current case on Earth, and that life would have developed there ab initio with different basic metabolisms that did not need to use potentially harmful radiation, but it might be the case that evolutionary pressure to maximise benefit from available energy (and/or other resources) always results in some exposure to hazardous excesses. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 22:17, 23 August 2023 (UTC)
 * Tangential, but it's important to remember the same processes that give an individual cancer also drive evolution. Anything that can alter the genetics of a cell such that it becomes cancerous also alters the genetics of cells to allow for genetic adaptations.  Can't have the one without the other, either life stagnates and never evolves past primitive forms, or some individuals die of genetic damage so that other individuals get mutations that give them a reproductive advantage.  -- Jayron 32 12:04, 24 August 2023 (UTC)
 * Mutations that drive evolution are mutations in the genome of reproductive cells, while the mutations that result in cancer are generally mutations in the genome of other cells. We could theoretically have the first while avoiding the second. --Lambiam 21:41, 27 August 2023 (UTC)
 * I think if someone had some spectrophotometer to measure wavelength, at night, to see if any UV-B comes from stars or moon. Though it would detect a lot of IR radiation 1st. Then, I wonder if anyone published whether that can cause cancer or vitamin D production. 170.76.231.162 (talk) 15:21, 24 August 2023 (UTC).
 * Stars are suns, just distant, so there will be exactly the same proportion of UV-B and IR in the light of any one of them as there would be if it were our Sun, depending on that star's particular colour temperature. However, since the light we receive from all the stars put together is much weaker than the light from the nearby Sun, the actual amount of UV-B and IR is negligable, though it is routinely measured for individual stars – astronomical spectroscopy does not confine itself to visible light.
 * Similarly the Moon's light is merely reflected Sunlight, but it's possible that the reflection from the Moon's surface alters the proportion of different wavelengths – maybe it absorbs more of the UV-B than the visible (and IR) light, maybe less: I'll leave the answer to another respondant (as I'm short of time), but as far as I know no-one's ever got a tan from moonbathing, unless that features in the next Mavis Dracula film. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 19:17, 24 August 2023 (UTC)
 * Light arriving from other stars is also affected - to various extents - by redshifting/blueshifting and absorption/scattering by the interstellar medium. But the amount of light which reaches us from them, on any and all wavelengths, is relatively trivial, as noted above. 199.208.172.35 (talk) 20:31, 24 August 2023 (UTC)