Wikipedia:Reference desk/Archives/Science/2015 August 26

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August 26

Majors for people interested in agricultural mycology?

Hi there, I know someone who lives on a mushroom farm (the legal kind you put on pizzas) and they are curious what the best major would be for them. Biology seems like it is too much pure science based. Horticulture seems too general and like it often doesn't cover anything to do with fungi. What majors should this student look into?--2602:30A:C019:2920:7422:8630:6271:A43C (talk) 00:09, 26 August 2015 (UTC)

A degree in microbiology is probably your best bet actually. According to this website, individuals should look for universities that offer courses in mycology but the general degree would be in microbiology. After you get your degree you can choose to specialize as there are Ph.D programs in mycology. --Stabila711 (talk) 00:21, 26 August 2015 (UTC)

I wouldn't be all that surprised if there actually is a major in agricultural mycology these days. In addition to "the mushrooms you put on pizzas", there are many other more exotic 'shrooms, like portabellas (favored by vegetarians as a meat replacement), and more broadly, fungi products like Quorn. Mushrooms (the non-poisonous kind) seem to be quite healthy, and many people like them, too, so I expect their consumption to rise, and hence for this increased demand to be able to support a major in the subject soon. (I try to eat some every day.) StuRat (talk) 00:31, 26 August 2015 (UTC)

Penn state has long historic ties with the commercial mushroom industry, as well as a minor in Mushroom Science and Technology [1]. SemanticMantis (talk) 01:00, 26 August 2015 (UTC)

In the US, many land-grant universities such as Cornell University offer a mixed program. One can attend the agricultural school, but take classes in the liberal arts college as well. I was a liberal arts major, but my botany classes as a bio major were 50/50 liberal arts and aggy majors. Your friend should also contact the relevant department heads to schools he is thinking of attending and discuss the issue with them. One very disappointing issue for me was that while Mycology 400 was in the catalog, the class was cancelled four years in a row due to underenrollment. Agricultural classes were not open to me, so I don't know for sure what they offered, but my interest was not in the applied field. μηδείς (talk) 00:40, 26 August 2015 (UTC)

A bit different from what you imply, but plant pathology is a major that combines those interests, and can lead to work that has high value both in terms of economic and humanitarian interests. E.g. things smut_(fungus) and rust_(fungus) are still very active research areas. Also opportunities for biological control, etc. SemanticMantis (talk) 01:00, 26 August 2015 (UTC)

Why are human stools so offensive?

In comparison to other mammals, why are human droppings so offensive. Rabbit pellets leave virtually no odour. Horse droppings whilst larger are relatively benign and not stink out. Same with sheep and cow faeces.

Yet, human stools smell the worst, far higher up the ick and gross factor than any of the mentioned above. I mean, just try getting dog (or human) crap off your shoes compared to say sheep droppings. I was even reading about farmers using sewage fertilise their fields and a whole town had to practically wear clips on their nose. Sure normal farm muck spreading is bad, but there's like no comparison. And, as a vegetarian (not quite a herbivore but still) the stuff is still far, far more foul than say horse droppings.

So what gives. — Preceding unsigned comment added by 81.198.8.129 (talk) 12:25, 25 August 2015 (UTC)

@81.198.8.129: This question belongs at WP:Reference desk/Science, not on the talk page. Do you want to move it there yourself, or would you prefer that someone move it there for you? (On the question itself, I would imagine that the fact that people [and dogs] are carnivorous, whereas the animals mentioned in your first paragraph are not, has a good deal to do with it.) Deor (talk) 13:24, 25 August 2015 (UTC)

Moved from talk page. StuRat (talk) 00:50, 26 August 2015 (UTC)

Skatole is one "offensive smell" component. Bile is the source of the brown color. It's used in the digestion of fats, so indeed is more common in carnivores. I'm not sure if a vegan diet would reduce bile production. As for why humans find these chemicals to be offensive, I suspect this evolved as a method to avoid picking up parasites and diseases from human feces. Herbivore feces presumably pose less of a risk of carrying diseases humans can contract, and herders needed some tolerance for these, so the evolutionary pressure to avoid those was reduced. StuRat (talk) 00:58, 26 August 2015 (UTC)

First of all, it is not offensive. If it is, then kindly explain why pigs love human stools? They could not eat enough of it. It is like KFC for them. 175.45.116.66 (talk) 01:12, 26 August 2015 (UTC)

I don't know any definition of the word "offensive" that has anything to do with pigs. Cholera is a good reason to find human stools offensive. Vespine (talk) 06:38, 26 August 2015 (UTC)

Disgust might be instructive here. --TammyMoet (talk) 11:24, 26 August 2015 (UTC)

This question was double-posted. I provided the same guidance as TammyMoet at WP:RDM. --Jayron32 13:57, 26 August 2015 (UTC)

Because it's your waste. The waste of each species is most offensive to that own species (more or less). Ariel. (talk) 19:07, 26 August 2015 (UTC)

Oh, surely cats are even worse than we are, no? Wnt (talk) 01:51, 27 August 2015 (UTC)

Skulls

Does eating a skull give you calcium? --Kew Gardens 613 (talk) 01:11, 26 August 2015 (UTC)

Yes, any bone does, although it has to be ground up to be digested. See bone meal. StuRat (talk) 01:25, 26 August 2015 (UTC)

Inert foodstuff for satiety whilst dieting

Are there any commercially-available inert food stuffs for people to use in achieving satiety while reducing calorie intake? I'm aware of Haitian dirt cookies that are made of some kind of clay. Shouldn't there be some such product available to the obese people of the west? --129.215.47.59 (talk) 09:29, 26 August 2015 (UTC)

Fruits and vegetables tend to do an excellent job of taking up space in your stomach while providing very few calories. Celery and iceberg lettuce are excellent for this, and strawberries are very good too, in addition to tasting wonderful. I would recommend them over clay since they are actual food. WebMD has a list of foods with almost no calories [2]. Someguy1221 (talk) 09:34, 26 August 2015 (UTC)

Dietary fibre. While I was on the F-plan Diet 30 years ago I had to eat these horrible tablets that you had to chew very well indeed before swallowing, and they would swell up in your stomach so you didn't feel hungry. They were mostly dietary fibre. --TammyMoet (talk) 11:23, 26 August 2015 (UTC)

As noted above, if you want to chew something high in dietary fiber which fills up your stomach and provides few calories, salad greens, lettuce, celery all fit the bill quite well. --Jayron32 14:42, 26 August 2015 (UTC)

Actually they don't. They are basically just packaged water. Celery's value as a dietary food lies in its "mouthfeel", you actually feel that you have eaten enough because of the amount of chewing you have to do! The high fibre foods in a Western diet (from memory here as we don't have an article on the F-plan Diet) are: the skin of jacket potatoes, haricot beans, wholemeal or rye bread, snd wheatbran. These foods all contain the sort of fibres that swell and absorb water in the gut. --TammyMoet (talk) 08:11, 27 August 2015 (UTC)

"Celery is used in weight-loss diets, where it provides low-calorie dietary fibre bulk." apparently. Alansplodge (talk) 20:57, 31 August 2015 (UTC)

There was this recent opinion piece, [3] but it seemed to ignore fibre content. Nil Einne (talk) 12:16, 1 September 2015 (UTC)

There's a variety of products like this - here's a few - [4] [5] [6]. SemanticMantis (talk) 14:31, 26 August 2015 (UTC)

Problem is that the "Molecular gastronomy" thing is mostly theoretical, the Attiva/Gelesis-100 stuff is still in clinical trials and won't be available for at least a couple more years - so the only actually available one is the SkinnyWip "FOAM!" - which appears to be on sale only in a very few stores in California - with their online store not being open yet. SteveBaker (talk) 15:02, 27 August 2015 (UTC)

The basic concept that you won't be hungry if your stomach is full is flawed, as a full stomach is only one of many factors that affect when you are hungry. Other factors that make you hungry are low blood sugar, nutrient deficiencies, seeing or smelling food, etc. And keeping your stomach full of low calorie foods 24 hours a day is quite a challenge. So, a more comprehensive diet plan will fill the digestive tract with fiber, but also provide all the needed nutrients, keep blood sugar from dropping too low or spiking too high, etc. And not having tempting foods around also helps. StuRat (talk) 16:54, 27 August 2015 (UTC)

Boiling Saltwater before drinking it, does it make any difference?

Can you drink/consume saltwater/Seawater if you boil it first? Will the salt evaporate, or will the water still be as salty as before? I should think it wouldn't make a difference, but I'm not sure, so I'm asking...

How about boiling food in Salt-water ?? How would that affect the food? Would the salt be absorbed into the food, and thus make the food so salty as to make it unhealthy?

2A02:FE0:C711:5C41:A040:6DEA:A306:28E1 (talk) 12:50, 26 August 2015 (UTC)

Boiling sea water will not cause the salt to evaporate. If anything, you will lose some water as steam leaving a more concentrated salt solution behind. However, if you condense the steam (a process called distillation) you can obtain drinkable water from sea water. Deli nk (talk) 13:06, 26 August 2015 (UTC)

To answer you other questions, you can cook food with sea water without making it unhealthy. It will add salt to what you are cooking and can be a reasonable way of seasoning a dish. Just Google "cooking with sea water" to learn more. Deli nk (talk) 13:10, 26 August 2015 (UTC)

Hm, yeah. Distillation. I can see how that works, and it is not new to me. Quite clever, though perhaps easier said than done if caught in a "survival"-situation with no access to fresh water and little or no tools. 2A02:FE0:C711:5C41:A040:6DEA:A306:28E1 (talk) 13:29, 26 August 2015 (UTC)

Drinking seawater has obvious harmful effects due to the salt content, and of course distillation can fix that. But aside from that, you got me thinking about whether drinking small amounts of seawater can be hazardous simply due to microorganisms, and whether boiling could fix that. The first example I could think of, brevetoxin in red tides, is "heat stable" according to [7] - it looks like it should withstand boiling (apart from secondary structure issues) like any protein, and it seems to have too simple a structure to be subject to protein denaturation like effects. So I'm thinking that boiling is, at first approximation, not useful - but I wonder if someone can think of an agent in seawater that could be killed by boiling. (Cholera in seawater near a beach contaminated by raw sewage would be an example, but not a natural one) Wnt (talk) 17:48, 26 August 2015 (UTC)

You've never been swimming in the ocean? It's not too hard to wind up getting a mouthful of seawater. I appear to be no worse for wear. Of course if the seawater does contain contaminants, it's a problem, but that's true of any water. My dad got giardiasis on a backpacking trip in Yosemite National Park. No seawater there! --71.119.131.184 (talk) 05:20, 27 August 2015 (UTC)

Yeah, I really wouldn't recommend anyone deliberately drink saltwater. People usually gag when they accidentally drink seawater for a reason. Drinking saltwater can lead to death as explained by this article from the National Oceanic and Atmospheric Administration. --Stabila711 (talk) 05:23, 27 August 2015 (UTC)

The typical body should be able to deal with a small amount of salt water, like ingesting a little bit of seawater while swimming, or even while gargling with table-salt water. Drinking it in quantity, like you would fresh water, is what would lead to big trouble. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:20, 27 August 2015 (UTC)

I've never been swimming in the ocean during a red tide. As with fresh water, seawater is sometimes particularly hazardous to drink. I have the sense that it is less often hazardous (apart from the usual salt) than fresh water, and of course red tides lead to consistent warnings over large areas. Wnt (talk) 11:36, 27 August 2015 (UTC)

"Human kidneys can only make urine that is less salty than salt water. Therefore, to get rid of all the excess salt taken in by drinking seawater, you have to urinate more water than you drank. Eventually, you die of dehydration even as you become thirstier." National Ocean Service - Can humans drink seawater? In the interests of balance however, (perhaps to be treated with circumspection) The Essential Health Benefits of Sea Water - The case for regular drinking of small amounts of sea water Alansplodge (talk) 20:07, 28 August 2015 (UTC)

While any water can contain contaminants, the likelihood of dangerous contaminants is going to depend significantly on where the water came from. For example, I suspect few would advise drinking from much of the Ganges. Similarly, aside from the normal risks of drinking sea water, some recent stories have suggested you probably should take particular care with the coastal waters of Rio [8] [9] as well. Nil Einne (talk) 12:11, 1 September 2015 (UTC)

Big Bang

Hello,

I hope you all good...

Q:

1. The 'singularity', when all the forces were combined, what was it as a whole, atomic particle or subatomic particle?
2. When it bursted and spread, did it spread in atomic particles or subatomic particles?

Space Ghost (talk) 18:44, 26 August 2015 (UTC)

1. We don't know. Per our Big Bang article, "if the known laws of physics are extrapolated beyond where they are valid, there is a singularity." The key phrase here, though, is not "singularity" but "beyond where [known laws of physics] are valid". We know that we cannot correctly describe the singularity.
2. Subatomic particles emerged before they were able to coalesce into atoms. Atomic nuclei emerged about 3 minutes after the Big Bang. Atoms with electron shells did not emerge for about 400,000 years. — Lomn 20:02, 26 August 2015 (UTC)

Cosmic_censorship_hypothesis may be relevant. The intro makes it seem as though Penrose thought that the naked singularity of the Big Bang did indeed exist in the universe, though that might just be poor phrasing or my misunderstanding. OP should recall that we are primarily discussing mathematical models when discussing the Big Bang, and not necessarily any true physical reality. SemanticMantis (talk) 20:13, 26 August 2015 (UTC)

One way to understand the problem with physics and singularities is to understand that a singularity (by definition) has literally zero size...not just very, very small...it's ZERO sized. So, suppose you want to do some simple calculation about the singularity? Suppose we know how heavy it was and wanted to figure out the density of the material? Well, density is mass divided by volume...but the volume is zero. If you grab a calculator, enter in any number you like for the mass of the universe (100, for example) - and try to divide it by zero - you get an "ERROR". That's because there is no valid answer for something divided by zero - your calculator can't do it - and neither can any standard arithmetic. So we can't use any of the normal laws of physics that entail needing to know lengths, volumes or densities because those laws just blow up in your face...ERROR!

It's not just the laws of physics that break down - even pure mathematics has a hard time when there are infinities and zeroes floating around everywhere.

It gets even worse than that because the laws of gravity depend on densities - and when the amount of gravity becomes either infinite or something-divided-by-zero, that breaks down too. Then Einstein's general relativity gets into trouble because the rate of passage of time depends on the local gravitational field strength...so if we can't calculate gravity, we can't calculate the passage of time either. If time itself is beyond the laws of physics - we really can't talk about the singularity in any meaningful terms. However, at the very first instant of the big bang, the size becomes something just a teeny-tiny bit bigger than zero - and then physics and math suddenly make sense, and we can talk meaningfully about what's going on.

So question #1 is really unanswerable - pretty much everything we'd like to know is fundamentally unknowable...even time itself has collapsed. Question #2 is easier - and User:Lomn has pretty much nailed that one for you already.

SteveBaker (talk) 20:26, 26 August 2015 (UTC)

You seem to have forgotten to include any references. Let me help out a little: Singularity_(mathematics), Gravitational_singularity, Null_set#Lebesgue_measure, Point_(geometry). SemanticMantis (talk) 21:27, 26 August 2015 (UTC)

And it is also worth mentioning that singularities and infinite values are frequently tamed in physics and applied math, e.g. renormalization and Regularization_(physics) - apparent singularities in a model are not always impermeable barriers to progress. SemanticMantis (talk) 21:36, 26 August 2015 (UTC)

Sometimes singularities are fixed by additional physics - for example, ultraviolet catastrophe. Also, a mathematical model may say that something reaches infinity (like the number of bounces by a steel ball on a steel plate) yet in practice it is underwhelming. In the case of black holes, some are saying Stephen Hawking's newest commentary on information retention is basically Fuzzball (string theory) all over again. [10] I don't know if the singularity at the Big Bang can be modelled by a fuzzball (if indeed matter was ever dense enough to form a black hole like density at the beginning, rather than just continually creating itself out of dark energy somehow...). Wnt (talk) 01:49, 27 August 2015 (UTC)

Thanks friends, I appreciate it.

What should I say?; Universe is where hypothesized multiverses are (I guess our Big bang universe should've been called 'bangedverse'/'shatteredverse'/'floweryverse'; something alike as stated), I guess its common to think that it came out of a 'starburst' because of the lifestyles' of a star.

Space Ghost (talk) 19:28, 27 August 2015 (UTC)