Wikipedia:Reference desk/Archives/Science/2015 August 19

= August 19 =

Name that phobia
A fear of being trapped in enclosed places with lots of people, as in an elevator full of people, but not being afraid of the being in the enclosed space alone, or being with those same people in an open space. StuRat (talk) 02:23, 19 August 2015 (UTC)
 * I think it might still fall under Agoraphobia. I believe even though the typical case is "open spaces" or "crowded places" it actually encompasses "any" environment which the sufferer identifies as "terrifying", such as a crowded elevator.  Vespine (talk) 03:52, 19 August 2015 (UTC)


 * Koinoniphobia, except that that includes open spaces. &mdash; Sebastian 04:05, 19 August 2015 (UTC)


 * It should probably be pointed out that from a medical point of view, one is discussing a form of social anxiety disorder - and that the medical establishment now discourages name-tagging 'diagnosis' of specific 'phobias' that seem to have roots more in etymological parlour-games than in psychology and psychiatry. Slapping an arbitrary label on a type of situation where an individual feels particular stress and anxiety does little to address the appropriate route to resolution for that individual. AndyTheGrump (talk)


 * Thanks for pointing that out. I was just about to look up a name for my fear of doing any paid work, which drives me to while away my time at Wikipedia. ;-) &mdash; Sebastian 05:42, 19 August 2015 (UTC)


 * Indeed, medically, there tends to only be discussion of the concept of "specific phobia", that is "You get anxiety from some specific thing", and since the treatment regime doesn't really depend on what the specific phobia is, there's no real medical or scientific basis in naming the specific thing with a fancy-shmancy Greek-sounding name. -- Jayron 32 10:32, 19 August 2015 (UTC)
 * Fear of work is Ergophobia - we probably shouldn't have an article on it, but we do. Tevildo (talk) 21:06, 19 August 2015 (UTC)
 * Claustrophobia would seem to cover it. Or you could invoke the ever-reliable pantophobia. ←Baseball Bugs What's up, Doc? carrots→ 05:19, 19 August 2015 (UTC)


 * Yeah - we get quite a few "name this phobia" questions here on the RefDesks - and the truth is that it's just a word-game. There are a small number of phobias (the ones you've heard of like claustrophobia) which are common enough as part of "the human condition" that they have names that actually matter - all of the other phobias are instances of various anxiety disorders which just happen to have attached themselves to different objects or situations.  It's as if the word "buy" or "purchase" had to be different for every kind of item you buy ("twisthandlepurchasing - the act of buying a screwdriver" - a word that I just made up, and I think everyone should use henceforth).  We don't do that - we don't need to do that - it would be ridiculous to do it.  But for some reason, phobias attract people who like to invent words and name things...partly, I suppose, because other people like to laugh at the idea that someone might have a mortal fear of...screwdrivers...or whatever.  So long lists of stupid made-up names attract people who like to either curate - or look up and read - random stuff on the Internet, then lists of phobias  get combined and added to, and propagate through social media and Readers Digest "Did you know" sections and such - and sometimes, people here on the RefDesks like to go and look them up for people who ask.


 * But the words don't matter - all but a few were made up by people with no medical standing to do so - so just don't go there, OK?! SteveBaker (talk) 14:46, 19 August 2015 (UTC)
 * That's how I also understand it. I would love a reliable source to add the above to Phobia and List of phobias, if you have it. Sjö (talk) 17:30, 19 August 2015 (UTC)


 * For those articles, you shouldn't have a problem:
 * It is a requirement of Wikipedia that all potentially debatable/controversial facts have references provided. That these conditions are recognised as having separate names - is highly debatable...I'm debating them right now...so without solid references, you can just delete them.
 * Phobia's are a medical matter - and so the references have to pass WP:MEDRS - which is a higher, and very precise, set of requirements for references.
 * If any of the names listed there do not appear in multiple medical books and journals - then delete them...that's the rules. I suspect that 90% of the names in List of phobias - and the articles they link to - would go away.  eg Oneirophobia - fear of dreams - mentioned in one pop-sci book, one time...not WP:MEDRS - so should be deleted. Repeat for the entire list - keeping the ones that are the subject of multiple studies in peer-reviewed journals. SteveBaker (talk) 20:58, 20 August 2015 (UTC)


 * Yes, it's a little bit like list of collective nouns - sure they can be fun and interesting in some cases, but there's little if any scientific value to detailed classification and specific names for each. I mean sure, it's fun to write "a pod of seals" but you will never have a problem is you write "a group of seals." SemanticMantis (talk) 18:48, 19 August 2015 (UTC)
 * I would like to point out that my first suggestion actually appeared in DSM IV as a diagnosable condition, well at least as a recognized subset of one. So I wasn't just playing the word games. Vespine (talk) 22:42, 19 August 2015 (UTC)


 * It might be helpful to have a name, for a couple reasons:


 * 1) I doubt if the treatment for every phobia is exactly the same. Some probably don't need any treatment at all.  For example, if you have a fear of snakes but don't live in an area with snakes, it's not really a problem.  For some phobias you can just slowly expose yourself to more of the item you fear, like gradually higher steps to fight a fear of heights.  Some other phobias might require medication.  A particularly absurd fear, like of apples, might require something like therapy to discover what childhood trauma caused it.  So, classifying which phobias belong in which category would be made easier if they have names.


 * 2) In some cases, society may make adaptations for certain phobias. For example, larger, open MRI machines are now made for the claustrophobic. StuRat (talk) 23:55, 19 August 2015 (UTC)


 * Your point 1 is an argument for a good scientific classification of fears according to the criteria you list, but not one for a special word for "fear of being trapped in enclosed places with lots of people, as in an elevator full of people, but not being afraid of the being in the enclosed space alone, or being with those same people in an open space". Point 2 has been nicely addressed by SteveBaker. To twisthandle his example somewhat so it fits your question, if you look at a tool catalogue such as this one, you'll see many descriptions that use more than a single word for an item, and yet those are happily supplied and demanded. While sometimes advertisements sport new coinages, I don't think that society needs those in order to meet specific needs. &mdash; Sebastian 00:56, 20 August 2015 (UTC)

Correlation of Microwave Radiation from the Sun at Different Locations
I am curious just how well microwaves received from the sun correlates between pairs of locations on earth or in space near earth. In particular I'm wondering how fast the correlation drops off with radial and tangential vector-to-sun differences when at a distance of around 1 AU.

Lets consider say a 10 MHz band of microwaves, centered around 1 GHz. For two antennas in space at the distance of earth's orbit from the sun, directed at the sun and right next to each other there would probably be perfect correlation in the received signals (assume no other microwave sources). If you move these antennas away from each other radially towards/away from the sun, how far will they have to be before you get a correlation of say 0.5. And what if they were to move away from each other tangentially (perpendicular to the towards/away vectors). Given the distance, size and irregularity of the sun, I can't even come up with a guess as to whether this would be on the order of meters, kilometers or thousands of kilometers. I imagine that this question may have been asked/answered in the field of telecommunications.

And when not done in space then there's also the question of how much total microwave energy is received directly from the sun, how much is scattered by the atmosphere and how much is (black-body) radiated by the atmosphere. 41.164.7.242 (talk) 12:33, 19 August 2015 (UTC) Eon


 * For the tangential case, you could put a lower bound on the distance by considering sources on opposite limbs of the sun (i.e. a pair of sources separated by the solar diameter). How far sideways could you move before the difference in the distances from the two sources changed by $$\scriptstyle{\frac{\lambda}{2}}$$ (so you moved between constructive and destructive interference of the signals from two sources)? By Pythagoras's theorem I reckon the answer is about $$\scriptstyle{\frac{\lambda}{2 \theta}}$$ where $$\scriptstyle{\theta}$$ is the angular diameter of the sun (about half a degree or 8.7mrad), so about 17 metres. Since the microwave sources will be distributed over the entire disc of the sun (so an averaged separation of less than the solar diameter), then allowable sideways movement would be greater than 17 metres.


 * For the radial case, the bandwidth would probably be the determining factor. --catslash (talk) 21:16, 19 August 2015 (UTC)


 * Thanks, you've given me a place to start. I guess I should have mentioned in the radial case that relative delay in signal is compensated for. By the way the reason I am interested in this is that I wanted to check the feasibility of building a passive Doppler radar system by analyzing direct and reflected microwave noise from the sun by analyzing the recorded noise pattern for time delayed and frequency scaled versions of itself using an SDR kit. So I was curious what distances this would work across. Baseball pitches: maybe. Asteroids or the moon: seems unlikely now. Either way, I can't find anything on the internet about the technique being tried before. 169.0.35.7 (talk) 05:06, 20 August 2015 (UTC) Eon


 * Em, Solar irradiance varies with position on the Earth's surface, and of course between daytime and nighttime. Perhaps that article will point to some relevant issues? . . dave souza, talk 21:52, 19 August 2015 (UTC)


 * Thank you for responding. I was referring to the correlation between samples in "noise" recordings from the sun, not the slow variations with time. I appreciate your assistance. 41.164.7.242 (talk) 08:47, 20 August 2015 (UTC) Eon

Can a lens be transparent for infra-red, but opaque for visible light?
Can you obtain an infrared image with a lens that's transparent for infra-red, but opaque for visible light? --Scicurious (talk) 16:43, 19 August 2015 (UTC)


 * Not necessarily a lens per se, but yes, passing IR but stopping visible spectrum can be done- see Optical_filter, Infrared_cut-off_filter, and some specific products e.g. here . Keep in mind, as pointed out in the cut-off filter article that "infrared filter" can be used mean both a filter that passes IR as well as a filter that blocks IR. SemanticMantis (talk) 17:35, 19 August 2015 (UTC)


 * Polycrystalline ceramics of the appropriate grain size (coarse enough to scatter visible light but not so coarse as to scatter IR) might possibly do the job - see transparent ceramics. --catslash (talk) 21:33, 19 August 2015 (UTC)


 * InfraRed is kindof a broad term. According to our infrared article, it ranges from: "700 nanometers (frequency 430 THz) to 1 mm (300 GHz)".  At the 700 nanometer end, it's just light that's slightly outside of our perceptual range...a tiny bit redder than "red".  At the 1mm end, it's more or less in the range of frequencies used in radar systems and microwave ovens.  In that most extreme 0.1mm to 1.0mm range, is a section of the infrared spectrum called "terahertz radiation".  Our Terahertz radiation article says that these waves are band of frequencies from 0.3 to 3 terahertz.
 * The significance of this is that these most extreme infrared frequencies are used at some of the fancier airport security body scanners. Terahertz radiation can pass through clothing, paper, cardboard, wood, masonry, plastic and ceramics - so long as it's not too thick - certainly materials that not much optical light will penetrate.
 * The answer here is a cautious "Yes" - but that answer depends on precisely where you place the limits on "InfraRed"...obviously there is no hard boundary in nature - and this ends up just being a question of human terminology.
 * SteveBaker (talk) 05:10, 20 August 2015 (UTC)


 * Germanium makes a good lens for transmitting infra red.--109.146.20.60 (talk) 13:01, 21 August 2015 (UTC)

Food: hot or cold, which is best?
From a health perspective, humans should eat food: hot, cold, tepid, or it does not matter? Please reply with WP:MEDRS-compliant information. Tgeorgescu (talk) 22:36, 19 August 2015 (UTC)

I am not asking about infections, nor am I asking about eating meat or being vegetarian. Is there reliable medical data that eating food at a certain temperature is harmful/beneficial for humans? Tgeorgescu (talk) 22:53, 19 August 2015 (UTC)


 * It's best to eat food without harmful bacteria, such as salmonella. As it happens, these die if food is heated up to 75 °C for 10 minutes. Another nasty one is E. coli, which thrive at 37 °C, a temperature that I would consider tepid.


 * And bacteria also do not reproduce happily at low temperatures. So, keeping food cold is an indication that there is not too much bacteria on it.


 * In summary, it does not matter at what temperature you eat. It only matters at what temperature you keep the food.--Scicurious (talk) 23:27, 19 August 2015 (UTC)


 * True, but it takes some time to change the temperature of food. If it's stored cold, then served hot, then the leftovers are stored cold, then reheated later, this means it needs to cross the danger zone several times.  Better to store it cold and serve it cold, from a anti-bacterial POV.  Of course, this assumes it doesn't require cooking.  For items that do need to be cooked, it's best to eat it all as soon as it cools enough to not burn yourself.  If there are leftovers, cool them quickly, store them that way, then serve them that way.  StuRat (talk) 23:32, 19 August 2015 (UTC)


 * I wouldn't want to eat infected food, be it hot, cold or tepid. So that's not the subject of the question. The question was something like: if I take well preserved food from the refrigerator, does it matter if I eat it cold or should I warm it? Of course, I don't discuss my particular case, but ask about research upon this matter. Tgeorgescu (talk) 23:45, 19 August 2015 (UTC)


 * You have to give us some clue of what you mean. I'm not sure what you mean by "infected food".  Realize that all food contains some bacteria, except for bottled foods that have been sterilized and not opened.  The object is to keep that bacteria from growing to an unacceptable level.  Warming food can potentially burn it, or get chemicals to leach of out plastic containers, either of which can produce toxic chemicals in the food.  Other than bacteria, digestion, and potentially harmful chemicals, I'm not sure what you are asking about, so please explain. StuRat (talk) 00:22, 20 August 2015 (UTC)


 * Ok, let's start from the assumption that there is definitely no unacceptable level of bacterial growth, no dangerous plastic stuff and so on. Does eating cold food vs. eating hot food make any difference in respect to health (like digestion, blood flow, fat deposits, properly assimilating all nutrients, producing certain illnesses, etc.)? Tgeorgescu (talk) 00:42, 20 August 2015 (UTC)


 * Well, there is an ice cream headache. And, of course, you can burn yourself.  But, failing those extremes, the food you eat quickly comes to body temp, so there really can't be much difference after that. StuRat (talk) 01:12, 20 August 2015 (UTC)


 * Reading your Q again, I'm guessing you are asking about digestion.  Digestion works best at normal body temperature, but any food you eat will quickly be brought to that temp. StuRat (talk) 23:38, 19 August 2015 (UTC)


 * Food can also be used to change your body temp, so hot food before going out on a cold day is a good idea, and cold food is good on a hot day. StuRat (talk) 00:29, 20 August 2015 (UTC)
 * I've found the opposite to happen - cold food stimulates my body to make even more heat than I started with, and hot food tricks my body into thinking it's overheated, so it cools down. (Written in small because it's anecdotal, and not directly relevant to the question.) Ariel. (talk) 02:10, 20 August 2015 (UTC)
 * Well, HOT food, as in spicy food, is most common in hot climates: Ethiopia, Thailand, India, Mexico, most of that food as far as I am aware is also server hot, not cold. The explanation I've heard is that it acts as a Vasodilator and in fact has a net cooling effect. I would not dispute that ONCE you are actually cold, like coming back in from cold weather, THEN you want a hot meal or drink to warm you up, but I'm not sure it works in reverse. Vespine (talk) 06:10, 20 August 2015 (UTC)


 * The exception to the rule on "hot climate = spicy" is of course Korean cuisine, most of Korea has a fairly temperate climate, not unlike the Northeastern U.S., and many Korean dishes are known for their piquancy, i.e. kimchi, gochujang, etc. -- Jayron 32 12:26, 20 August 2015 (UTC)


 * Presumably spicy food became common in hot areas because food quickly spoiled there before refrigeration, and the spices helped to mask that. I could also buy that the sweating it induces cools the body, although they might still "feel" hotter.  However, for eating hot (temperature) food to have a net cooling effect, you have to assume that the body for some reason overcompensates for that heat.  I see no reason why that should be. StuRat (talk) 03:21, 21 August 2015 (UTC)


 * "People used spices to hide the taste of spoiled food" was what I was told at school, but the modern scientific interpretation is that spices were used as preservatives. Iapetus (talk) 10:07, 21 August 2015 (UTC)


 * That isn't really what the article concludes:


 * “One of the things Hayley found is that there seems to have been a preference to put the garlic mustard in pots that contained fish,” says Craig. “That might be associated with covering the smell, or even have had a role in preserving the fish.” Still, he prefers a simpler explanation. “I think there may not have necessarily been a functional role here,” he says. “It might simply be down to the aesthetic of taste. We just like these spices.”


 * Only a few spices are capable of preserving food, and then only if you use quantities that make the food almost inedible. Salt, for example, can be used, but then you need to mix the super-salty food with something else to dilute the salt before eating it.  Basically, spices bacteria don't like we don't like either, at the same concentration, although we are able to dilute them, which they can not.  StuRat (talk) 00:19, 23 August 2015 (UTC)