Wikipedia:Reference desk/Archives/Science/2021 October 26

= October 26 =

Why do radio still need power if antenna providing it?
Antenna converting EM waves into electric current, then why do radio still need power to work? Rizosome (talk) 00:00, 26 October 2021 (UTC)
 * The simplest type of radio, the crystal radio requires no additional power. However, the volume is so low that you must use earphones. I used one as a child to listen to the radio when I was supposed to be sleeping. Additional power is needed for amplification. Cullen328  Let's discuss it  00:08, 26 October 2021 (UTC)
 * The amount of power that can be extracted from an antenna is no where near enough to power the typical radio. It serves only as a signal, not a power source.
 * In the early days of AM broadcast radio, there were simple "crystal" radios that were unpowered, and extracted enough power from the antenna to power an earphone, but they were much less satisfactory that the powered radios of the day, and were vastly inferior to today's radios. Jc3s5h (talk) 00:10, 26 October 2021 (UTC)
 * What is the mechanism (or process) called, from converting frequency to electricity? 67.165.185.178 (talk) 00:43, 28 October 2021 (UTC).
 * The radio frequency is electricity... Otherwise, I'm not sure what you mean by mechanism? Radio receiver is a good introduction, and leads to lots of more specific information about specific designs in different articles.  To hear radio, you use the signal to drive a speaker cone, in the case of a crystal radio, the speaker cone is a tiny one inside an earbud, which is small enough that the tiny amount of electricity in the RF signal is enough to drive the speaker.  For larger speakers, you need an external power source to drive an amplifier, which as the name implies, increases the power of the input signal so it can drive a larger speaker.  -- Jayron 32 12:20, 28 October 2021 (UTC)

Mushroom identification
Splendid mushroom seen in October on downland in the south of England. Any ideas? ITookSomePhotos (talk) 12:23, 26 October 2021 (UTC)
 * There are a LOT of options here, but the closest I can see from a quick glance at that website is Agaricus langei or Agaricus moelleri. There are a LOT of mushrooms in the Agaricus genus that have a similar appearance as well. -- Jayron 32 13:14, 26 October 2021 (UTC)
 * Yes, there are so many. Agaricus augustus has a scaly cap like mine. Some pictures of it have brown gills and/or a different shaped cap, but both these properties apparently change during the life of the mushroom. ITookSomePhotos (talk) 16:40, 26 October 2021 (UTC)
 * I'm not an expert, but it seems to be a parasol mushroom, Macrolepiota procera (see commons), which is very common across temperate Europe, and typically pops up in October. No such user (talk) 14:11, 27 October 2021 (UTC)
 * Please can we all show some self control in identifying photographs of fungi unless we really know what we are talking about. Mistakes here can be fatal. I am not an expert either, but this certainly is one of the parasol mushrooms, so the first identifications as Agaricus spp. were well off. That makes me worry that another time a poisonous fungus will be identified here as an edible one. Jmchutchinson (talk) 18:34, 27 October 2021 (UTC)

What's the most practical solution if a future virus or coronastrain needs something around N99?
Apparently N99 masks exist but are hard to breathe through, would it be possible to strap a mouth-only mask+noseplug combo to the head that would be N99 and easier to breathe through than the current N99 mask? A lot of the Ns of these N95+ masks is turbulence lengthening the path through the mask matrix and increasing the chance of sticking to a mask fiber, would an N99 nostril filter that you roll to compress and wait a few secs for it to expand to airtight be easier to engineer? Or would some people have to start wearing gas mask-looking things in public? Sagittarian Milky Way (talk) 16:33, 26 October 2021 (UTC)
 * If it does, we'll be in deep doo-doo, but it seems to me unlikely. Naïve anti-maskers sometimes look at the dimensions of a virus and claim that because it's smaller than the width of the paths through a mask, masks must be ineffective. What they fail to understand (or deliberately ignore) is that virions from the lungs do not float about individually in the air, they are mostly carried within droplets of moisture that are much, much larger than they are and usually too large to pass through a mask unimpeded. {The poster formerly known as 87.81.230.195} 90.200.65.29 (talk) 18:03, 26 October 2021 (UTC)
 * Or you could simply accept some people will die a bit younger. Influenza- and coronaviruses aren't known for killing more than a few percent of the infected people, even if left untreated, and have a preference for people who are already relatively close to death. At some point you have to make a decision of how much discomfort you want to bring to the strong to stretch the lives of the weak. It won't be a popular decision and politicians tend to avoid it, but it's necessary to take that decision one day. PiusImpavidus (talk) 08:33, 27 October 2021 (UTC)

"Relationship of eaten and eater"
I once read that the formula of evolutionary game theory, which describes the relationship between predator and prey, also describes that between parasite and host. My question is: Does this also apply to plant and plant eaters?--2A02:908:426:D280:7100:3AFC:91AC:329B (talk) 18:41, 26 October 2021 (UTC)
 * Which plants are known for eating other plants? ←Baseball Bugs What's up, Doc? carrots→ 20:17, 26 October 2021 (UTC)
 * That's not relevant to the question. It was not phrased in a way that necessitated plant eaters being plants. --OuroborosCobra (talk) 20:33, 26 October 2021 (UTC)
 * The vegetarian couch potato. Admittedly a rare species. Clarityfiend (talk) 21:32, 26 October 2021 (UTC)
 * See parasitic plant. 85.76.64.219 (talk) 10:55, 27 October 2021 (UTC)


 * It may apply to some combinations of (plant species, plant-eating species), in particular when being eaten is detrimental to the plant species. Frugivores can be viewed as plant eaters, but in more than a few cases the plant species has become dependent on the eater species for reproduction, so the relationship is then one of mutual benefit. Cultivars such as Brussels sprouts would not exist if they mounted a vigorous defence against being eaten. But such things as having thorns or prickles can be explained as evolutionary adaptations offering some protection against being eaten, and the leathery tongues of horses or goats can be seen as an evolutionary adaptation to overcome the challenges of munching on thistle. That may set off an evolutionary arms race; one can imagine thistles getting pricklier and goat tongues getting tougher in a feedback spiral. There are probably better examples, in which the antagonistic co-evolution is demonstrable. --Lambiam 21:30, 26 October 2021 (UTC)


 * The questioner needs to be more specific about which model they are referring to: a variety of game-theoretic models have been applied to different aspects of the predator-prey interaction. Models in game theory are typically highly simplified abstractions of reality that try to isolate some component principle. Typically the models should be considered as "thought experiments", used to gain understanding of the processes, feedback-loops, and stable equilibria, rather than to make quantitative predictions. No real situation fits the assumptions of such simple models perfectly, but they may have enough in common that the same principles operate in both. It is often a judgement call how relevant a given model is to a particular organism's interaction with others. Jmchutchinson (talk) 18:25, 27 October 2021 (UTC)


 * Not exactly what the OP was suggesting, but plants do compete for area space, root space, water, nutrients and light, with some also adapting to live under the shadow, wind protection and humidity provided by large-leaf plants (and some other plants will die in these "invasive" conditions)... Once an area is full, there'll still be competition among the same/native plants there.  As dead plant material decomposes this provides nutrients for the others.  — Paleo  Neonate  – 22:43, 28 October 2021 (UTC)

Radiation on Ganymede
I notice at Ganymede (moon) that Ganymede's magnetosphere has closed field lines only up to about 30° latitude. So, my question: is Ganymede's magnetic field strong enough to create any substantial differences in radiation level between its equator and its poles? Double sharp (talk) 22:49, 26 October 2021 (UTC)
 * Yes, it is strong enough to make a difference. For example, the difference in radiation levels is sufficiently large to create bright polar caps. Ruslik_ Zero 20:18, 27 October 2021 (UTC)


 * This link may be more convenient. —Tamfang (talk) 03:35, 28 October 2021 (UTC)