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October 3

Sugar conductivity

During a chemistry lab experiment, my group was determining the conductivity of three unknown substances A, B, C (which we believed to be salt, sugar, and baking powder, respectively). We put 5 grams of each substance into 50mL of distilled water, and tested the conductivity of each separately (after washing the tester, of course). Despite our hypotheses, we found that substance B did have a slight conductivity, despite being watered down with distilled water and wiped clean. Later, I figured this was because, if B was indeed sugar, its polarity and dipole-dipole forces would play a part in making the water slightly conductive, while others thought it was just human error by not cleaning the tester well enough. Thoughts? Thanks! 174.93.62.131 (talk) 00:08, 3 October 2013 (UTC)

Perhaps because table sugar separates into sucrose and fructose at a certain rate in water? Been far too long since I did that experiment myself. μηδείς (talk) 00:26, 3 October 2013 (UTC)

Ash content of sugar is measured by conductance of the solution; refined sugar should have no more than 0.04% ash. Don't know how much this "ash" conducts, but you could assume it's salt and calculate the expected conductivity, see if it comes close. You did check the distilled water first? (should be about 0.5 to 3 µmhos/cm). Ssscienccce (talk) 01:01, 3 October 2013 (UTC)

The ash contains silica as a major fraction, however the remaining fraction is indeed an assortment of salts. Plasmic Physics (talk) 01:20, 3 October 2013 (UTC)

• The OP is essentially correct. Sucrose does have labile hydrogens, which will give it a very slightly ionic character. Also, even pure water will have a very slight conductivity due to the autoionization of water. Depending on the sensitivity of your conductivity test, either of these factors could give a small positive result. It probably wouldn't light a bulb, but if you have a sensitive meter, you may detect a very small current. --Jayron32 01:48, 3 October 2013 (UTC)

Yep. I would think autoionization would be the most likely explanation. DI water tends to run pretty acidic. A pH of 4 would give you a hydronium concentration, [H3O+] = 0.1mM. Not only that, you might have dissolved CO2 present in your DI water, which would further contribute to the ionic strength of your solution, since you'd make carbonic acid. (+)H₃N-Protein\Chemist-CO₂(-) 11:00, 3 October 2013 (UTC)

Purified water#Electrical Conductivity has some conductivity data for various types of "purified" water. DMacks (talk) 05:47, 5 October 2013 (UTC)

Space-time origami

Is it in theory possible to fold space-time, not just bend it? It would be a nice idea if space-time could copy electromagnetic radiation, by reflecting and refracting. I'd really want to see the straw in a glass of water effect without the water or air. What would be necessary to reallise this possibility, graviton beams? Plasmic Physics (talk) 00:33, 3 October 2013 (UTC)

We can answer your questions about known physics. What we really don't do here is write science fiction stories for you. --Jayron32 01:43, 3 October 2013 (UTC)

There is a sliver of an acceptable question in there, and one which now I wonder as well: Can spacetime "curvature" be non-differentiable? Someguy1221 (talk) 03:35, 3 October 2013 (UTC)

Are you talking about a discontinuity? Plasmic Physics (talk) 04:01, 3 October 2013 (UTC)

Because, if you are then that is exactly what I'm asking. Plasmic Physics (talk) 04:05, 3 October 2013 (UTC)

Not a discontinuity in spacetime, but a discontinuity in the rate of curvature. I'm not sure what you mean when you say "fold", but it made me think of the gridlines describing the shape of spacetime taking a sharp turn instead of gently curving. Someguy1221 (talk) 04:06, 3 October 2013 (UTC)

Is the question, "Can this happen in general relativity?" or "Is there a speculative framework in which it can fold/nondiff?" or "Does anything we know forbid this from ending up as the case in quantum gravity, etc?". I don't have an answer to any of them off the top of my head, but each is a very different question- also, what exactly do you mean by "fold"?Phoenixia1177 (talk) 04:24, 3 October 2013 (UTC)

There is a discontinuity in spacetime's curvature at the gravitational singularity at the center of a black hole. A non-rotating black hole just has a point singularity, but a rotating black hole, also known as a Kerr black hole, has a ring singularity along a circular line. However, the Kerr geometry may not actually exist in nature; the realistic gravitational collapse of objects into rotating black holes, and the resultant geometry, is an active research topic. Red Act (talk) 04:46, 3 October 2013 (UTC)

Origami involves folding paper without cutting or rejoining it, which has no effect from the perspective of general relativity, since it's only connectivity within the "paper" itself that matters. If you cut a wedge out of the paper and tape those edges together to get a cone then you have altered the connectivity of what's left of the paper. A straight cosmic string has a geometry similar to this, and if there was a straight cosmic string between us and a distant object (like a galaxy), we would see two identical images of the galaxy (see Cosmic string#Observational evidence). -- BenRG (talk) 13:23, 3 October 2013 (UTC)

Gravitational fields of massless particles. Count Iblis (talk) 15:13, 3 October 2013 (UTC)

All is helpful. Thank you. Plasmic Physics (talk) 08:11, 5 October 2013 (UTC)

Ionic bonds

I've come across a somewhat perplexing thought after a lab today, where we dissolved salt into distilled water. It took 52 seconds, longer than other substances like sugar, and it got me thinking. According to my chemistry notes, my textbook, and my teacher, ionic bonds are the strongest of intramolecular bonds (between atoms), and stronger than intermolecular bonds. The teacher explained how more energy is needed to separate the bonds, explaining why salt has such a high boiling point. However... when salt is dissolved in water, the sodium and chloride ions separate simply by being stirred in with water, but this takes considerably less energy to perform, no? If so, why does water make it to much easier to separate individual ions if their attraction is so strong? Thank you. 174.93.62.131 (talk) 03:23, 3 October 2013 (UTC)

I'm going to make a stab at it, it's most likely to be the solvation effect. Water molecules coordinate to the ions, stabalising the charge over a greater area, meaning that it is energetically favourable for the ions to separate into solution. Plasmic Physics (talk) 03:28, 3 October 2013 (UTC)

The rate at which a chemical change occurs cannot be inferred simply by knowing how energetically favorable the change is. Solvation of salt in water is far more favorable of a change than the solvation of sugar in water, but reaction kinetics are far more complicated than simply knowing how favorable a change is, and are generally difficult to predict from first principles. In the case of solvation, reaction rate is further complicated by the rate of diffusion of the solute from the (temporarily) solid mass, a factor which is mitigated by stirring (or "agitating" if we want to use chemist-speak). Someguy1221 (talk) 03:33, 3 October 2013 (UTC)

The OP didn't ask about the rate. They asked why water makes it easier for the ions to separate. Plasmic Physics (talk) 03:39, 3 October 2013 (UTC)

Sorry, i was just addressing the opening sentence, in case he was wondering. Someguy1221 (talk) 03:48, 3 October 2013 (UTC)

To answer the solvation part of the question, solvation can be conceptualized as three different processes working together:

1. Breaking the bonds between solute particles (i.e. separating the sodiums from the chlorides)
2. Breaking the bonds between solvent particles (i.e. separating water molecules from each other)
3. Forming new bonds between the water molecules and the solute particles

The first two steps are always endothermic (disfavorable) and cause increases in entropy (favorable), while the last step is exothermic (favorable) and causes a decrease in entropy (disfavorable). From a thermodynamic point of view, something will dissolve so long as the free energy (i.e. the sum of the enthalpy and entropy components of all involved processes) is negative. The reason salt dissolves, even though the bonds between the ions in the salt are very strong, is that in the end the bonds between the water molecules and the sodium and chloride ions are stronger, at least in the sense that the dissolved state is thermodynamically favorable vis-a-vis the undissolved state. --Jayron32 04:57, 3 October 2013 (UTC)

This article (Ion-association) should give you a rough idea. The dielectric plays a huge role on dictating the extent to which an ion pair will dissociate in a particular medium.(+)H₃N-Protein\Chemist-CO₂(-) 10:50, 3 October 2013 (UTC)

Equation

So... I'm making a poster, and for it I'd like to have an equation that relates (or at least tries to relate) sonwflake shape to the kinetics of its formation, can you help me? thanks in advance.--Irrational number (talk) 07:53, 3 October 2013 (UTC)

Well, there are fractals which look very much like snowflakes. You could include the equations to generate those. See Koch snowflake. StuRat (talk) 11:13, 3 October 2013 (UTC)

This paper contains a number of equations pertaining to the formation of real snowflakes; take your pick. Red Act (talk) 15:15, 3 October 2013 (UTC)

Concrete mixer truck

When a concrete mixer truck gets stuck in traffic for some hours and cannot deliver the concrete, could the concrete damage the truck? OsmanRF34 (talk) 22:00, 3 October 2013 (UTC)

Yes. I'd guess that SOP would be to dilute the concrete as much as possible and then pour a big pile at the side of the road. We run into similar problems when the electricity supply to the foundry gets cut. Lots of rock hammers and ear muffs for days. Greglocock (talk) 22:57, 3 October 2013 (UTC)

Another great opportunity to differentiate between what's probable and what's possible.

Normally, additives are included in the mix to delay setting. "How much" can be fairly easily estimated based on time in transit, ambient temperature, and so forth. Plus, you'll note that the mixer is slowly but constantly rotating, which also makes it more difficult to set up enroute.

But, is it possible? Sure, anything's possible given enough time, enough weird assumptions, and a bit of just plain bad luck. (What if the truck runs out of gas and can't keep stirring the mix, etc.)

And, if you're merely asking about does an extra hour of mixing abrade the lining of the mixer ... I don't know that one.

--DaHorsesMouth (talk) 23:04, 3 October 2013 (UTC)

No, I am asking about the truck not being able to deliver at all. Obviously, they'll try to avoid it, but I imagine that that could happen and in a big city. Dumping it won't always be possible. I thought that maybe some extra emergency additive could spoil the concrete on purpose and it would solidify (even if that would mean to through it away). OsmanRF34 (talk) 23:30, 3 October 2013 (UTC)

Concrete delivery trucks have a tank of water. If stuck in a traffic jam, the driver cand add water to the mix which, together with the agitation, will both retard setting, and make the set concrete weak. Adding water without agitation will not achieve anything. Don't know about the USA or other countries, dumping concrete on the side of the road in my locality would attract a huge fine for the driver, and possibly sanctions against the concrete company if it happened more than once. It will be much cheaper to, if necessary, sacrifice the mixer drum. Engine failure or running out of fuel is quite unlikely. A diesel engine idling in traffic consumes very little fuel compared to when travelling at speed. Incidentally, concrete trucks here used to have a separate 6-cylinder gasoline engine to power the drum. But some years ago, GM decided to cease supplying the engines to the truck manufacturers, so they changed to using a hydraulic rotation motor powered from a power take off (PTO) on the road engine. Much simpler, cheaper, and far more reliable. And eliminates the possiblity of leaving the depot without enough gasoline. 121.215.151.241 (talk) 00:25, 4 October 2013 (UTC)

Note that concrete mixer mentions the use of jackhammers and dynamite to deal with the situation. Wnt (talk) 00:37, 4 October 2013 (UTC)

Yes, but no reference for this is given. I'd like to know how the author thinks anyone could get in inside a space that small and use a jackhammer, or even drill some holes to place dynamite. The hole down the middle between the mixer plates is about large enough for a 12 year old at most to crawl down. About as likely as being randomly assigned $10,000,000 from a bank official in Nigeria I reckon. What is far more likely is that the driver takes the whole lot back to the depot, they remove the barrel/drum from the truck, cut up the barrel with an oxy-acetylene torch to expose the set concrete, then break that up with jack hammers. Meanwhile, a new barrel would have been installed on the truck. It's only sheet metal anyway. Barrels have a forward access plate secured with bolts to facilitate cleaning, but that won't do any good if the whole load has set. 121.215.151.241 (talk) 01:40, 4 October 2013 (UTC)

Removing concrete from the agitator bowl of a concrete truck with a jackhammer is a standard procedure in the industry, called "chipping"[1] or "de-dagging".[2] There are even companies that specialize in performing that procedure.[3] Red Act (talk) 02:15, 4 October 2013 (UTC)

I learn something new everyday - and here I stand corrected. They must use special small men or midgets and tiny jackhammers. However, the thrust of your second citation (a website of a company that cleans the barrels) is essentially, this is very very dangerous method, so don't do it unless you really really have to, and then you need to treat it as confined space per the Confined Space Act, which means a man outside doing nothing but keeping watch, and you must have a written plan to cover safety, communication, and person extraction aspects. Elsewhere in that website it says that they don't ever do it by entering with jackhammers. They use machine directed high pressure water nozzles. A link at the botton of your second citation links to a Govt safety authority, Worksafe Australia. They actually forbid men entering the barrel, and suggest using high pressure water. That will not always work - in such cases the solution I gave above seems to be the only reasonable approach. Next time I have some concrete delivered, which is part of what I do as an engineer, I'll ask a driver what he thinks/knows. The website you cited in your third reference gives no clue as to how they do it. 121.215.151.241 (talk) 03:09, 4 October 2013 (UTC)

(EC) Various sources [4] [5] [6] seem to confirm a jackhammer is used for cleaning the inside of a concentre mixer. These seem to be mostly referring to buildups rather than a full load, but it also seems clear from these sources people do go inside the concentre mixer without opening it for cleaning so I'm not sure your argument that the opening is too small holds. This source [7] other than confirming the jackhammer bit further (and also the going inside), also makes it clear someone tried dynamite once. It suggests it didn't work well for them, but it wouldn't surprise me if despite the source making it sound like they're the fountain of all learning in the field, that others have implemented and use it more successfully. That source also suggests they do deal with full loads and while it isn't entirely clear it does suggest they use jackhammers for the purpose. Considering the price given in that source $0.09 per pound (USD I presume), it's perhaps not surprising. The bowl/mixer may 'only' be sheet metal, but I'm guessing a new bowl could easily cost well over $5000 [8] [9] (even taking in to account what you recover from the metal). Yet as per article Concrete mixer and other sources [10], a full load is only likely 40k pounds or so meaning the price for this real world commercial company cleaning a full load (~$3600) will be well under a new bowl cost. P.S. From the sources it's apparent the cleaning was feature in an episode of List of Dirty Jobs episodes. From our article, I think it was in "Termite Controller" with a follow up in "Tight Spaces 2". Nil Einne (talk) 03:20, 4 October 2013 (UTC)

Reading our article more carefully, it actually mentions Mythbusters tried to use dynamite. While they also evidentally had little success, I've never been that impressed with the quality of Mythbusters experiments and it wouldn't exactly surprise me if they made a poor attempt at what someone else with the expertise regularly does. Of course it also wouldn't surprise me if the use of dynamite is indeed a complete myth which someone added to our article. I'll tag the claim in any case. Nil Einne (talk) 03:48, 4 October 2013 (UTC)

(This reply after reading the ECs above.) I found someone with these Dirty Jobs shows so had a look. While I obviously can't upload anything to wikipedia or associated sites, I do belief a small number of shots would be resonable under US fair use law so have uploaded them here [11] although if you disagree feel free to remove the link. It's obviously not that easy to get in but isn't that hard (for the host who's not a "midget") and this concrete mixer looked to be a small one. I'm not sure this was a full load but it looks to be more than simple build up. Of course this is the host and there's I presume a camera person inside so nothing here is necessarily typical but I would presume the jackhammer is one they would normally use in some cases. The host does mention it's fairly claustophobic but not simply because of the confined space but also because of the sensory deprivation due to the ventilator plus eye and ear protection plus sensations from the jackhammer although none of these would be unique to working inside a concrete mixer. BTW my impression from the links is that at least in parts of the US, using a jackhammer is still quite common. While there are those who promote different methods, I presume different health and safety and other requirements means different practices in different localities, as with many things. I would also note that while this is obviously quite a dangerous job with several risks, the fatality examples given by the Australian vendor above ([12]) while obviously saddening, seem to actually relate to poor work practices namely failing to properly secure the barrel beforehand rather than the dangers of the job itself when carried out in a resonable manner. Nil Einne (talk) 07:33, 4 October 2013 (UTC)

I've certainly learnt something new today. So men certainly do get inside and use jackhammers. The jackhammers indicated are definitely small ones though. Also, you are right, all your references are about removing concrete films built up during normal use, not a full load as relavent to the original question. I certainly would not disagree with your estimate of the cost of a new drum/barrel. But that's still a lot less than the fine a road-side dump would attract. Not fogetting that the authorities would probably make the driver/company remove the dumped concrete and make good any roadside surface or grass etc - which could also cost roughly around $5K. 1.122.115.40 (talk) 11:01, 4 October 2013 (UTC)

Slightly off topic with the original query (though Osman mentions "some extra emergency additive") but I recall that a way to stop concrete setting, or at least greatly delay it was to throw a few kilograms of sugar in to the mixer. Yes, here's a source mentioning it15 to 20 pounds of sugar. "concrete with that much sugar in it would never set up. I would lose the concrete but save the mixing drum". Apparently Coke works too (not Diet I imagine!) -ӄ- 220 of ^Borg 06:51, 4 October 2013 (UTC)

You have triggerred a memory of when I was studying engineering at University several decades ago. Salt will also render concrete extremely weak. But where is a concrete truck driver goig to get 20 pounds or so of sugar or salt in when stuck in a traffic pileup? 1.122.115.40 (talk) 10:45, 4 October 2013 (UTC)

In the cab of the truck or some other similar storage location? Since we're obviously talking about an ordinary emergency measure I would assume if anything was done or could be done, the driver could be trained for such an eventuality and for something like sugar or salt which is relatively harmless, it could be stored without issue (well for salt you might need special measures if it's a lab in NZ but I'm not sure those would apply to a concrete mixer). If these are not done, I presume it either because they're not very effective or they don't want the truck driving messing with the concrete and the risks and problems that entails. Speaking of safety, I'm not sure encourage the driver to add stuff to the concrete in random places, particularly in the middle of traffic even if it's stopped would be considered a good idea. (In other words, it doesn't seem storage or locating the salt or sugar would be a problem.) The other alternative would be installation of a special device to dispense the concrete that can be operated, perhaps from without the cab. However that sort of thing may get to the level of added cost and complexity that it won't be worth it, particularly given the risk of such a device failing and screwing up the concrete without anyone noticing until it's a bit late. Nil Einne (talk) 13:10, 4 October 2013 (UTC)

October 5

3D printer that can make a copy of itself

Can a 3D printer be made that can make a copy of itself? 3D printers are rather slow, but even if it takes a week for one printer to make a copy if itself, in a year's time you'll have enough to cover the entire Earth's surface. Count Iblis (talk) 01:12, 5 October 2013 (UTC)

Given that 3D printers incorporate quite a lot of complex electronics etc, not at the moment, no. They can produce many of the mechanical parts though: see RepRap Project. AndyTheGrump (talk) 01:25, 5 October 2013 (UTC)

Not to mention that why would you want it to replicate? It is a very expensive way to make an inferior product as far as many parts go. And if you want a vast number, conventional mass production methods are far cheaper and quicker. 3D printing is good for "feel it in your hand" checking the design of parts, and seeing how a device with many parts goes together - somewhat similar to the use of wooden mockups by aeroplane designers before CAD/CAE visualisation tools became available. 1.122.115.40 (talk) 05:37, 5 October 2013 (UTC)

Lots and lots of people for a long time have thought about building self-replicating machines for various reasons. Certainly not practical with anything like today's 3D printers, but it would be a major first step. Staecker (talk) 12:10, 5 October 2013 (UTC)

One consideration is that you would have to start with a pile of raw materials big enough to cover the entire Earth's surface. 173.62.242.128 (talk) 11:12, 5 October 2013 (UTC)

Thanks, the RepRap Project looks interesting. Perhaps one day you could make self-replicating machines that will eat up entire planets to make Dyson spheres, traveling from one solar system to another until all the stars in the entire galaxy are surrounded by Dyson spheres. Due to the exponential increase in the number of machines, this would not take very long. Count Iblis (talk) 20:05, 5 October 2013 (UTC)

3D printers, in their present developmental stage, are pretty primitive machines. Even if people report having printing this or that, its possibilities are very limited, both regarding the form of the output as well as the plastic used. OsmanRF34 (talk) 22:45, 5 October 2013 (UTC)

• See grey goo. μηδείς (talk) 04:50, 7 October 2013 (UTC)

Neanderthal diets

Is there any estimate for how many calories in the adequate neanderthal diet, and also what kind of food was mostly eaten (what kinds of meats, grains etc.) — Preceding unsigned comment added by 174.88.241.119 (talk) 04:07, 5 October 2013 (UTC)

See Neanderthal behavior#Diet. Seems like we don't know much about that topic, and no doubt it varied hugely according to habitat.--Shantavira|^{feed me} 07:18, 5 October 2013 (UTC)

Brains and muscles burn the most calories, and Neanderthals had bigger brains and were more muscled than us sapienses. μηδείς (talk) 16:30, 5 October 2013 (UTC)

Why does skin feel nicer after a shower?

Given people use moisturizer, I would assume skin would feel nicer without the oil washed off. But it seems, at least to me, to have a nice "just-showered feeling". Can anyone explain this? Thanks. μηδείς (talk) 05:06, 5 October 2013 (UTC)

Hmmmm. I wonder how many people use moisturizer? I don't. HiLo48 (talk) 05:34, 5 October 2013 (UTC)

It's a girly thing. They like to put all sorts of liquids, oils, and greases on their skin. I've never understood why. I always feel better after I have used soap to get all oils etc, whether my skin's natural production, or otherwise (eg oil or grease on my skin from working on machinery), off. Recently my lady had an ECG check. The electrodes would not stick to her skin. The cardiologist then said "this often happens with women, but never with men. Please come without any moisturiser on next time." 1.122.115.40 (talk) 05:44, 5 October 2013 (UTC)

Moisturizer is for dry skin and it is also essential if one wears make-up. Plus dry skin makes people look older. Young people have natural "dewy" skin. I have family and friends who've spent their lives out in the sun of Southwest U.S. and their dry skin looks like leather. Contrast that to people who live in more humid environments (think tropics) where skin isn't so wrinkled. Probably the good feeling you get from showers is the same one gets from exfoliating...you're removing dirt and dead skin cells. But your body needs the oils that your follicles produce. Liz ^{Read! Talk!} 02:31, 7 October 2013 (UTC)

I like lotion and moisturizer on occasion, it feels nice and smells good. Skin care is not the exclusive domain of women. On a side note, that there are "girl things" and "boy things" pisses me off a little, women get way better clothing; I'm looking forward to the day I can wear a kick ass antique style dress in public.Phoenixia1177 (talk) 06:09, 5 October 2013 (UTC)

Horses for courses. I like wearing a good business suit. There is great freedom to choose a nice shirt and tie. 1.122.115.40 (talk) 10:54, 5 October 2013 (UTC)

Suits and shaving went pretty much the same for me: they were really awesome, at first, but once I had to doing/wearing it/one everyday, they got boring pretty quickly. As for the dress (I wish I had pictures) I recently played a women that wore one in a small play my friend wrote; with everything done right, it looked absolutely awesome (I don't think I could figure out the hair and makeup though:-( ).Phoenixia1177 (talk) 11:03, 5 October 2013 (UTC)

I'm male and use moisturizer, but I consider it a medical necessity. I use it on my feet, which otherwise get so dried out the skin on the soles cracks and bleeds and would then become infected. Similarly for my lips, where I use lip balm. It was interesting when I shopped for some lip balm in Charlotte, NC. Unlike the North, where we keep it in the pharmacy section, in the South they think it's so "girly", they put it next to lipstick. I'm not sure if this is purely a cultural difference, or partially due to dryer weather in the North in winter, making things like lip balm more of a medical necessity. StuRat (talk) 01:07, 6 October 2013 (UTC)

Looking around on Google, it appears to be a common feeling and common question, but I didn't see any definitive answer. A lot of people seem to think that the heat makes your muscles feel good and that there are various psychological factors. Is it specifically your skin that feels better, or do you just feel better, in general, but notice it in your skin? (that sounds like something a serial killer might ask...I can't think of a better wording though). Personally, mines the former, but there do seem to be certain physical indicators of a feeling of "betterness".Phoenixia1177 (talk) 06:09, 5 October 2013 (UTC)

I've given this some thought and, as it happens, I've had my daily shower. It makes me feel good because 1) the warm water is relaxing; 2) the heat tends to fix muscle stiffness, and 3) getting rid of the oils that naturally accumulate on the skin allows the cooling effect of sweating to work much better with less perceived sweat. I note that in hot climate areas like Australia, people enjoy a shower or bath every day. In cold climates such as England, at least until recent times bathing only every second or third day or even once a week was the norm, driven by the desire to look good and not smell. This tells me that either they were too skinflint to tolerate the cost of water heating, or they don't feel better after bathing lie us folk in warm climates do. 1.122.115.40 (talk) 10:52, 5 October 2013 (UTC)

I live in the UK and in the 1950s and 60s and even into the 70s most people didn't have central heating or showers, no double glazing and poor insulation. There was usually ice on the inside of the windows on cold, damp winter mornings and you got dressed under the blankets. Heating up water for a bath using a coal fired boiler or electric immersion heater was a long and comparatively expensive business and you only got one shot at getting the temperature right. Then once you'd had a bath you had to get dressed in a freezing cold bedroom. Also families were bigger before the contraceptive pill came along. The worse-off people in small terraced houses often had an outside toilet and no bathroom and had to fill up a zinc bath in front of the fire in the living room or use public baths. All-in-all not conducive to bathing more than once a week. I remember talking to one of our South African research students in the 70s and she said that when people in SA told her she wouldn't want to bathe every day in the UK she didn't believe them, but once she got here the cold reality of the British winter was something of a shock and her habits changed. I'm sure this is why the Australians love to make jokes about Pommie immigrants not washing and hiding their money under the soap. Richerman (talk) 15:23, 5 October 2013 (UTC)

The muscle thing is a big one for me; I have tourettes and twitch my neck muscles constantly, and painfully, so after a really warm shower is usually the best that I feel all day. It's also a good place to think, if you aren't quick about it, sometimes mulling over the past day can be relieving. Interesting point about differences and climate; I'm going to see if I can find something on the subject going in that direction later- someone had to write a paper about this somewhere (seriously, there's paper on if you should, shouldn't, leave up toilet seats...)Phoenixia1177 (talk) 11:03, 5 October 2013 (UTC)

We have "his and hers" ensuites in our house. That's even better. Mine stays up and hers stays down. 1.122.115.40 (talk) 11:06, 5 October 2013 (UTC)

• The muscle thing is a separate issue. I take hot showers when I have a sore muscle/muscles. But any old shower (assuming I use soap, not just water) will give my skin a distinct "smooth" feeling for a few hours that is very pleasurable. As for moisturizers only being for women, many black men use them too, or they will get "ashy" skin. Whatever the phenomenon is I am looking at, it has to do with the surface of the skin, not the muscles. μηδείς (talk) 16:29, 5 October 2013 (UTC)

Thinking about this further, I wonder if there is also an effect because the hands themselves are cleaner, and better able to feel. μηδείς (talk) 18:47, 5 October 2013 (UTC)

Not everyone likes to shower or take a bath: According to this article: "

King Louis XIV stench came from the fact that his physicians advised him to bathe as infrequently as possible to maintain good health. He also stated he found the act of bathing disturbing. Because of this, he is said to have only bathed twice in his lifetime. Another in this “gruesome two-some” class among the aristocracy was Queen Isabel I of Spain who once confessed that she had taken a bath only twice in her lifetime, when she was first born and when she got married." Count Iblis (talk) 19:46, 5 October 2013 (UTC)

Will Cuppy repeated that story about Isabel, and added a footnote that "They gave her a third one after she died." ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:44, 5 October 2013 (UTC)

Along the same lines, there is the (probably apocryphal) story that the color isabella, a yellowish-brown, was named for the color of her underwear... - Nunh-huh 02:37, 8 October 2013 (UTC)

One thing I've wondered is whether people who bathe infrequently or not at all might have a different bacterial flora that is better adapted to that condition, so that they might smell less than someone who abruptly stops after a lifetime. (By and large the smelly compounds are lipid products like small carboxylic acids, still highly reduced and, in theory, could be oxidized by microbes for energy) But I doubt anybody funds research into this one. :) Wnt (talk) 20:16, 5 October 2013 (UTC)

Did you hear about the masochist who liked taking cold showers? So he had hot ones. HiLo48 (talk) 22:40, 5 October 2013 (UTC)

I am not sure how this got onto the smell of Frenchmen and the sexual proclivities of German nobility. μηδείς (talk) 21:12, 6 October 2013 (UTC)

I think in regard to Liz's suggestion above, the exfoliation question makes sense, the lessening of the thickness and roughness of the skin seems a plausibe answer. I wonder how much skin comes off on average? μηδείς (talk) 03:17, 7 October 2013 (UTC)

Side Effect -vs- Symptom in Psychological Disorders (context = psychopathy)

In some disorders, there are "side effects" that are commonly observed with the disorder, but are caused by it- for example, people who are insensitive to pain, suffer more injuries; autistic people saying inappropriate things in certain situations. People with psychopathic personality disorder have poor impulse control, I was wondering if this could be a side effect of an inability to empathize and experience guilt. I imagine that guilt/empathy would be a strong motivator to dissuade us from many of our impulses. On the same subject: people who are insensitive to pain can learn to not injure themselves (as much), autistic folk can learn to recognize certain social cues intellectually, etc. Even if you can't teach a psychopathic individual to empathize, could you teach them to have better impulse control/less violent behaviour? Most generally, can certain disorders be viewed as a lack of certain psychological senses, and for those that can, is there an analogy to learning to compensate with other "senses"? (in the sense of the example cases given) (psych isn't a subject I actively study, so please be charitable with anything that seems outright stupid, I may be describing this poorly given my ignorance of the subject).Phoenixia1177 (talk) 06:32, 5 October 2013 (UTC)

The essence of what you are saying is well known: Yes, you can teach a person to synthesise whatever aspect iof their psychological makeup is missing. It is quite normal for them to teach themselves if their handicap is not too bad. This is the reason why high performing autistics / asperger's people improve with age. It is also the reason why highly intelligent people with Autism, psychopathy, etc, do much better than others with the same problem but have more ordinary intelligence - something that is well known in psychology and psychiatry.

Over time negative reactions and feedback from other people result in them working out what they are doing wrong and they learn to correct for it. The process can take some time, years, both because it may be not so easy for them, and also because it can take a long time for situations in which they react inappropriately to be experienced. For instance, a highly intelligent autistic person may become extremely proficient in electronic engineering, designing many really good products which earn the respect of others. With this level of respect they might move after, say, 10 years at work, into a supervisory role. Then of course they will prove at first to be a none too good boss because of their not so good ability to relate to their team. They are now in a situation requiring interpersonal skills that were not tested before - but with experince they will get better at it.

Being a succesful manager in a highly competitive field can derive benefit for a small degree of psychopathy. Impulsiveness, a degree of not caring so much about employee's feelings, and drive, helps them get their team to perform. But they won't be welll liked - again an intelligent boss will pick this up and learn to modulate how he drives people.

You should not forget that definitions of pschological "problems" like autism, asperger's etc" are partly culturally determined, and what negative impact they have is culturally determined. There is no term for Asperger's Sysndrome in many non-European languages of the world - not only in lay language, but in professional language as well. In a nomadic hunter-gatherer society, an Asperger person would simply be regarded as a highly skilled hunter, or spearhead maker, or some such, and might well become tribe chief on that strength. Perhaps an extreme cultural example is an elderly male who persistently has sex with girls under 14. In Western society, such a person would be regarded as a pervert, sent to gaol, and most likely be diagnosed with something by a government appointed shrink. In traditional Australian Aboriginal society, he would be regarded as normal. (Note: the author, who is male, does not at all think that screwing 14 year olds is a good idea in modern Western society.)

See articles in Scientific American in the last 2 years or so on Asperger's Syndrome and Autism for a more complete explanation of this. SA had an article on the positive aspects of psychopathy about 8 to 12 months ago as I recall. 1.122.115.40 (talk) 10:16, 5 October 2013 (UTC)

Mental illnesses are multidimensional, five are used in the Diagnostic and Statistical Manual of Mental Disorders #Multi-axial system. This relates to the psychological senses that you allude to. --Digrpat (talk) 13:02, 5 October 2013 (UTC)

Is the tricuspid valve identical to the semilunar valve?

Diagram of the human heart

When I learn about the heart valves, I see that the shape of tricuspid valve and semilunar valves are the same in their shape. Both of them has the same shape (and it says that the semilunar valves also may to called as tricuspid, theoretically) Do I understand well? 95.35.222.1 (talk) 11:47, 5 October 2013 (UTC)

All the heart valves have basically the same shape; that doesn't mean anything. There are two semilunar valves, the aortic valve and the pulmonary valve; neither of them is identical to the tricuspid valve, which connects the right atrium with the right ventricle. See our heart valve article for more information. Looie496 (talk) 15:42, 5 October 2013 (UTC)

Apparently it is possible to culture mesenchymal stem cells to produce a "semilunar valve" which, short term, seems to stand in for the natural structure, without taking any particular steps to make it know it's a semilunar valve with transcription factors, etc. [13] So at least in concept it seems like they ought to be relatively interchangeable ... still, I bet if you look closely enough, the cells will turn out to know where and what they are. :) Wnt (talk) 20:27, 5 October 2013 (UTC)

• Isn't the simple answer here that tricuspid valves have three cusps and semilunar valves are shaped like a half moon? μηδείς (talk) 21:11, 6 October 2013 (UTC)

Well, our article points out that they can have 2 or 4 leaflets ... and the number of these may even change during a lifetime (I haven't checked that, but it is certainly an astounding idea that illustrates the true plasticity of the structure). But actually, looking over the article just now, it mentions the lack of chordae tendinae, which I'd forgotten about. Wnt (talk) 23:56, 6 October 2013 (UTC)

That's almost impossible to believe! Two and a half valves won't work. Maybe they split over time? μηδείς (talk) 04:48, 7 October 2013 (UTC)

I can think of a lot of hypotheses, but I don't believe any of them. :) Wnt (talk) 16:21, 8 October 2013 (UTC)

Do batteries exposed to the cold lose their ability to produce power permanently or just temporarily?

I've seen what the effects of cold are on a battery after trying to snap some pictures while skiing with a digital camera. I only got a few before it was spent. My question is, do batteries regain their capacitance, their potential for electric generation, if they are exposed to cold but are later brought up to room temperature. Vranak (talk) 13:12, 5 October 2013 (UTC)

In the cold a battery will discharge faster, but it shouldn't damage it. Batteries generate electricity through a chemical reaction. Lowering the temperature causes chemical reactions to proceed more slowly, so if a battery is used at a low temperature then less current is produced than at a higher temperature. OsmanRF34 (talk) 15:05, 5 October 2013 (UTC)

In fact, many people store batteries in the freezer -- not rechargeable batteries generally, but I don't think those should be harmed either as long as they're brought up to temperature before being used. Looie496 (talk) 15:29, 5 October 2013 (UTC)

I am not sure they last longer if stored in the freezer, but yes, they work again after coming back to the expected working temperature. OsmanRF34 (talk) 15:32, 5 October 2013 (UTC)

Thank you guys. Vranak (talk) 02:31, 6 October 2013 (UTC)

I am interested in the question too, and not enlightened by the answers so far. Sometimes it seems to me that battery-powered gadgets, in the cold, lose power quickly. Is that because the battery is cold, and is the effect permanent (meaning that I have to replace the battery, as I usually do when this happens), or will waiting a while in the warm restore the power? It would be handy if I knew I didn't have to go and grab a fresh battery on these occasions.

What I don't understand in the above: "discharge faster" seems to contradict "reactions proceed more slowly". Then, "discharge" implies a permanent loss of charge, while "less current" implies a temporary loss of ability to power a gadget. Finally, "work again" doesn't say whether they will have lost some of their charge after being cold, or not. 217.169.13.12 (talk) 03:29, 6 October 2013 (UTC)

Temporarily until they warm back to room temperature. See Battery (electricity). Batteries are normally stored in a fridge by suppliers so they don't discharge and rechargeables don't lose their ability to hold a charge so quickly. Dmcq (talk) 11:13, 6 October 2013 (UTC)

I wonder if these is some confusion here? From what I can tell, the OP isn't simply referring to storing batteries at low temperatures but actually using them at low temperatures. In that case, from what I can tell from our article and my limited understanding of this area, I think capacity is actually permanently loss. In other words, if you use a device for 1 hour with the batteries at low temperature, even after it warms up again the capacity remaining will be lower than if you had waited for the batteries to warm up before using the device. (This assumes power draw for the device remains the same which may not be the case.)

Of course if you've stored the batteries at room temperature for 2 years, then use them with a device for 1 hour you may end up with less capacity remaining than if you stored the batteries at a low temperature for 2 years then use them with a device at the low temperature for 1 hour because self discharge etc may mean more capacity was lost during that 2 years, so none of this means you shouldn't store your batteries at a low temperature even if you're sure you won't have time for them to properly warm up.

Now if you use batteries at a low temperature for a while and they can no longer or barely power the device and allow them to warm up, you will likely find they work for a while longer (and not just because leaving them for a while will often mean that) and if you have rechargable batteries then all you have to do is recharge them (the remaining capacity was lost but not the capability of holding a charge) but I'm not sure if that's what's the OP is asking. (And I think we've established that if you store your batteries for 2 years at room temperature before you use them they will be worse than if you store your batteries at low temperatures for 2 years and then allow them to warm up before you use them.)

Nil Einne (talk) 14:11, 6 October 2013 (UTC)

I don't know the answer but my guess would be that when you warm them up quite a bit of the charge will appear again. Some energy would I guess be lost due to greater internal resistance whilst discharging but Idon't think that would be a big effect and I can't see there would be any other energy loss. A good project for some schoolchildren? Dmcq (talk) 15:58, 6 October 2013 (UTC)

While I am not familiar with the battery behaviour itself, if the cold serves to increase the internal resistance of the battery and thus drop the voltage at the terminals while under load, most modern devices will compensate by drawing a higher current to meet the power demand of the device. This would result in the device genuinely discharging faster (exacerbating the voltage drop further). If the voltage drop is enough, the device could decide that the discharge threshold has been reached almost immediately, in any event while the battery is still holding more charge than it normally reaches this threshold at. Thus, if the internal resistance increase at low temperatures is the dominant mechanism, I'd expect both effects: more rapid actual discharge, and cutout with a higher level of charge still present, which would become available if the battery is warmed. None of this suggests that the battery would suffer any damage, or that the life of the battery would be reduced (aside from having to be recharged earlier). — Quondum 05:54, 7 October 2013 (UTC)

October 6

SAM system guided by phased array radar whose components are distributed over a wide area

Why don't countries like Iran who have difficulties acquiring conventional air defense systems like the S-300 build their own systems using modern electronics? It seems to me that you can quite easly build a phased array radar that consist of a large number of small antennas spread out over a big area. Such a radar system cannot be taken out by a few airstrikes (it will remain functional if some fraction of the antennas are taken out). This radar can guide missiles toward aircraft and these missiles don't need to be located near the phased array antennas. It seems to me that such a system would be less vulnerable than the S-300 system (which needs to be protected by short range SAM systems). Count Iblis (talk) 03:22, 6 October 2013 (UTC)

I can't answer the question directly, but our articles on bistatic radar, multistatic radar and passive radar would be relevant. Acroterion (talk) 03:33, 6 October 2013 (UTC)

Is there any reason why Iran could not master the technical details of a large area phased array radar? As an engineer myself (and who has met refugee Iranian engineers trained in the USA pre-Islamic Revolution), I don't think so, technically. And who knows what secret stuff they may have in the pipeline However, what gets developed in various countries depends on many things, not just technical know-how.

Firstly, the field is specialised, and you need not just good engineers but engineers who are keenly interested - otherwise they just won't have the specialist skills, which take years to acquire. An interesting example is the World War 2 developement of radar. Japan tried to develop good radar equipment without much success a they had no enginners interested and thus having acquired specialist knowlege. Germany had some success. Great Britain had considerable success, as it happend they had scientists and engineers already interested in the technology, ironically having learnt of a key development (magnetrons) in pre-war Japan. USA also had success due to their immense industrial might. Some of the best WW2 field portable radar equipment was developed independently in Australia - it just so happened there were a handfull of chaps with the right skills.

Secondly, what gets built and what doesn't, depends on how well the political leaders (invariably in any society the people who are technology illiterates), who control the money, understand things. It can happen that they just don't think an advanced technology can be developed locally. An example of this is the development of advanced large bomber aircraft in the USSR imediately after WW2. Their leaders in the Kremlin clearly understood the need, but didn't think their aircraft industry could come up with the goods. So they ordered their aircraft industry to produce exact copies (Tupolev TU-4) of the American B-29, based on what they could learn from 3 captured examples and a great deal of espionage. The USSR was a fully metric country, and the USA of course non-metric. So, even though the USSR was already able to make aluminium alloys as good as any (in metric sizes) and all manner of parts, and engineers as good as any in the West, they ended up constructing a complete set of non-metric industries, requiring immense investment and training, just so they could make the B-29/TU-4. Clearly, it would have been cheaper and better to design their own bomber completely from scratch, based on indigenous materials & parts, rather than go for an exact copy. But Stalin didn't realise that. After his death, they designed their own quite succesfully.

1.122.56.195 (talk) 11:58, 6 October 2013 (UTC)

I agree it seems a relatively straightforward task to design a multistatic array and use it to control the SAM. Some idle thoughts (1) you still have emitting stations which can be taken out in all sorts of cheapish ways. (2) A multistatic array is inherently more expensive for a given level of performance than a monostatic one, so the aggressor has already scored a partial kill since fewer systems can be built for the same money. (3) maybe stealth isn't that big a threat, it may have been over-sold by its proponents. I'm not convinced that any of those is right but they are possible. I'd certainly expect some country with a large supply of technology graduates and expertise in electronics and telecoms to develop such a system if those objections don't apply. Greglocock (talk) 02:03, 7 October 2013 (UTC)

The wiki nannyware won't let me link, but a google search on problems with implementing multistatic radar arrays came up with loads of hits. Computational load comes up as a big part of the issue which is surprising to me, but the MIMO systems I analyse have relatively high S/N ratios (50 dB at worst). Greglocock (talk) 03:01, 7 October 2013 (UTC)

Interesting! I was thinking about using this to deal with an enemy that would likely gain total air superiority like in case of Libya against NATO. If Gaddafi had bought a few S-300 systems these would still not survive indefinitely under the NATO attacks. They could be engaged using misslies from beyond its range or by aircraft flying in low to attack it directly (that depends on how well it is protected by short range SAM systems).

But if instead of conventional radar systems you have a huge number of dipole antennas spread out over a huge area, there won't be good targets for NATO to hit to destroy the SAM system to make the airspace safe for them. Count Iblis (talk) 14:37, 7 October 2013 (UTC)

Not too sure if this might not be better on my or your talk page, but the individual receivers and transmitters aren't what you'd hit, you'd go for the computing network and guidance radio, by choice. The computers are working all the time by necessity so they are the easiest to find. Greglocock (talk) 22:24, 7 October 2013 (UTC)

Depending on the radars' location, they could also be destroyed or sabotaged by commando teams, as the Egyptian SAMs were during the Yom Kippur war. 24.23.196.85 (talk) 05:57, 8 October 2013 (UTC)

Anomolous nature of LiAlH4

LiAlH₄ is a reducing agent. then why does this reaction occours ?

    CH3                                  CH3
    |           LiAlH4                   |           
H3C—C—CH3     ——————————→            H3C—C=CH2
    |
    Cl

— Preceding unsigned comment added by Sa29nchit (talk • contribs) 15:07, 6 October 2013 (UTC)

LiAlH₄ is a Lewis base and a nucleophile. When it attacks certain types of molecular structures, for example, a carbonyl, the effect is a reduction of them. It's not a pure "donate loose electrons" type of reducing agent, the definition students are often taught in lower-level courses. But even your reaction is a reduction in a simple sense: the "H⁺" that is lost from the organic structure becomes a neutral hydrogen. Always important to look at all of the products and byproducts, not just the main organic structure. I fixed the ASCII-art layout to be what I think you meant: the HTML tags especially were not considered when using "space" to align the lines. DMacks (talk) 17:06, 6 October 2013 (UTC)

Islamophobia

Is "islamophobia" listed or mentioned as a mental disorder in DSM-5? --72.66.30.115 (talk) 17:21, 6 October 2013 (UTC)

No. AndyTheGrump (talk) 17:25, 6 October 2013 (UTC)

If if were a mental disorder, would it be listed in DSM-5? --72.66.30.115 (talk) 17:33, 6 October 2013 (UTC)

Why not? What hasn't been in or out of that list of quackery pandering to big pharma? Myles325a (talk) 03:41, 8 October 2013 (UTC)

Wikipedia does not provide answers to hypothetical questions. AndyTheGrump (talk) 17:39, 6 October 2013 (UTC)

(edit conflict) Answers accepted. (But the right answer to the second question was: very probably yes.) Thanks, Andy. --72.66.30.115 (talk) 18:11, 6 October 2013 (UTC)

As Andy says we cannot answer that hypothetical, but based on its ommission from DSM-5 we could say that "Islamophibia is not a recognized mental disorder in DSM-5" (if you actually want to say that in a wikipedia article, you'll perhaps need a secondary source making that observation, in order to avoid WP:OR).

More broadly: Not being a recognized mental disorder in a DSM does not mean that the concept is itself invalid or fictitious. For example, per my search, DSM-IV does not have a listing for "sexism" or "racism" but you'll be hard pressed to convince many that those phenomenon do not exist. Abecedare (talk) 18:01, 6 October 2013 (UTC)

Thank you, too, ABCDare. (except that racism and sexism aren't mental disorders). --72.66.30.115 (talk) 18:11, 6 October 2013 (UTC)

While political correctness is? μηδείς (talk) 21:09, 6 October 2013 (UTC)

"Islamophobia" is normally used to mean an ideology. As Phobia#Terms_for_prejudice explains: "A number of terms with the suffix -phobia are used non-clinically. " That's the same as being communist. Another different thing would be having an OCD with Islam as the object of obsession. OsmanRF34 (talk) 21:07, 6 October 2013 (UTC)

Without touching on Islamophobia, but rather addressing the OP's follow-up question If it were a mental disorder, would it be listed in DSM-5?: What is or is not a mental disorder is a matter of professional judgement, and the DSM's inclusion or exclusion of something represents the professional judgement of some, but not all, respected professionals. So there's no way of compiling an exact objective (non-judgement-based) list. So what many people do is perhaps the next best thing: they go by the DSM. If we go by the DSM in defining what is or is not a mental disorder, then the answer to If it were a mental disorder, would it be listed in DSM-5? is tautologically yes. Duoduoduo (talk) 21:18, 6 October 2013 (UTC)

So are other famous phobias (agoraphobia, arachnophobia, acrophobia) and countless more one reads about) individually and specifically listed in the DSM mentioned, or are they subsumed in some general condition describing anxiety and behavioral limitations in the presence of or when thinking about some stimulus to which the individual is sensitive? Edison (talk) 23:32, 6 October 2013 (UTC)

Any phobia is typically going to be a mental disorder in cases where it overwhelms the individual's ability to conduct a normal life. A lot of Christians and Jews are wary of Muslims. It's fair to say that a lot of Muslims are going to be wary of Christians and/or Jews. That doesn't make it a mental disorder. However, if someone convinces himself that a given group is "out to get him", despite the lack of any such evidence, and then goes into a place of worship and shoots everybody, there's a good chance that guy has a mental disorder. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:17, 7 October 2013 (UTC)

We have the DSM5 article, the table of contents is at [14] ... I don't see anything about Islamophobia or other obvious "hate" or "religion" based terms. (If someone wishes to enlighten us further, I notice that The Pirate Bay tracks a torrent for it... I haven't checked on relative risks of book downloads lately, but I don't hear much about it in the news) I wonder if psychiatrists in Islamic countries diagnose people who burn Korans, blaspheme Muhammad, or attempt to proselytize Christianity as having conduct disorder? Whereas I suppose followers of Islam or other banned religions in countries that prohibit them might be diagnosed with it? But I don't really do well at understanding psychology. Wnt (talk) 04:14, 7 October 2013 (UTC)

Something like that, in Saudi Arabia - 'deal with reports of students making fun of Islam's rituals or discussing subjects and ideas that violate Islamic law through "behavioural adjustment and life-skills sessions"'  Card Zero  (talk) 20:36, 7 October 2013 (UTC)

Here's a good model for calling islamophobia a disease, rather than a political epithet: Political abuse of psychiatry in the Soviet Union. μηδείς (talk) 04:28, 7 October 2013 (UTC)

I suspect that most of you are sort of missing the joke. Some people love to make up names of specific phobias, more as linguistic trivia than as psychology, "ailurophobia", "triskaidekaphobia", etc etc ad tedium. There's no real value in distinguishing these, but it's a fun game for some people, along the same lines as "a murder of crows". The OP is trying to fit "Islamophobia" into the same mold, either as humor or to make some sort of point, I'm not sure which. --Trovatore (talk) 04:33, 7 October 2013 (UTC)

I fear I am missing the joke as well. I could see if this question were at the language desk looking for an etymology. But the term has no medical origin. It's used to conflate certain ideologically political positions like support for Israel with lunatics who shoot at Sikhs because they wear turbans. μηδείς (talk) 04:45, 7 October 2013 (UTC)

Hmm, making stuff up, eh? Like having an irrational fear of instant replays, "Slomophobia". Or of the moons of Mars, "Deimos-and-Phobos-phobia". Or pretending to be afraid when you're not, a "fauxbia". Fear of the Irish, "O'phobia". Or for that matter, fear when I slam the door - hence, "I-slam-o-phobia". ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:14, 7 October 2013 (UTC)

Trovatore, the OP wasn't trying to be funny or playing games; he was just asking for someone to look something up for him. He had boldly stated at the NPOVNoticeboard: [the word islamophobia] "is as phony as a three dollar bill—there is no such mental condition as an irrational fear of Islam" and the next commenter asked for a reliable source for that assertion. --72.66.30.115 (talk) 05:35, 7 October 2013 (UTC)

Oh, so then it was the second possibility, "to make some sort of point". But it's frankly sort of a silly point, because the term "Islamophobia" is not intended in that sense at all. It's usually used in the sense of "bigotry against Muslims", and there is no implication that it's a mental disorder. --Trovatore (talk) 06:18, 7 October 2013 (UTC)

On this page I asked a simple question. On the WP:NPOVN page I agreed with the AP and Salman Rushdie. Does that clear up your confusion? --72.66.30.115 (talk) 06:41, 7 October 2013 (UTC)

The reason for describing it as "phony" is straightforward—it appears to be the name of a mental disorder, a phobia, but turns out to be no such thing. --72.66.30.115 (talk) 17:21, 7 October 2013 (UTC)

This isn't all verbal mockery. Remember, "Islamophobia" follows on the heels of "homophobia", which in turn presumably has its roots in "homosexual panic", an actual psychology concept used most disreputably to try to provide a defense, even a justification, for people attacking and killing gays. The creation of the term is indeed a rhetorical coup, that confuses fear and hatred, irrationality and vehement rational rejection. (It is continued even here by various categorizers here and at Commons who classify Islam and Judaism, but not Christianity, as religions you can have "racism" against) Wnt (talk) 17:48, 7 October 2013 (UTC)

The term "phobia" gets used colloquially in ways that don't qualify as mental illnesses. As with words like "paranoid" or "schizoid" or just plain "You're crazy!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:18, 7 October 2013 (UTC)

Sal ammoniac for soldering and "tip refresher"

I'm not particularly skilled in soldering (electronics). Sometimes the soldering tip blackens, particularly if I'm using a soldering gun. I was advised that sal ammoniac is useful in tinning a tip but with my soldering gun it seems that any progress I make on one side of the tip is negated by the blackening on the reverse. What chemical reactions are occurring? Does it matter if the sal ammoniac turns brown or even black? Should I try to remove the black deposits from the sal ammoniac? What is their chemical composition? I bought "tip refresher" which is somewhat expensive per unit mass. That product eliminated the black deposits on the tip and made it shine like new but it didn't take long to start to turn brown. If tinning with solder is required to protect the tip, why wipe it off again using a wet sponge? Does it matter if the sponge has turned a dark grey (presumably a deposition from the tip)? — Preceding unsigned comment added by 2.97.26.56 (talk) 19:25, 6 October 2013 (UTC)

Sal ammoniac is electrically conductive, so I would not use it on a soldering iron to be used on electronic circuits, as it could cause unwanted conductive paths if it got on a circuit board or bridged between terminals. It is better suited as a flux for stained glass lead or other crafts. I get a soldering iron hot then remove deposits with a wet sponge and reapply electronic solder (tin-lead alloy with rosin flux) to leave a shiny coat on the iron when it is stored.. The wiping removes oxidation products and dirt. Here is a soldering guide from Radio Shack [15] and one from the Weller soldering iron company via electronics seller Digikey: [16]. The Wikipedia article Soldering iron has a section with a "how-to" of cleaning, and it says that newer lead-free solders are more of a challenge as to keeping the tip clean. Acid core flux is good for plumbing, but bad for electronics use, since it can corrode the PC board traces and provide unwanted conductive paths: [17]. Edison (talk) 23:26, 6 October 2013 (UTC)

In any case, soldering guns should not be used in electronics. Several decades ago they were sometimes by radio and TV servicemen on tube based equipment (which was more tollerant of too much heat) repaired in people's homes, due to the almost instant heating, but never by properly trained technicians doing high quality work on professional equipment. The advent of precision temperature controlled irons such as the Weller TC-5 about 40 years ago rendered soldering guns obsolete in electronics, as they heat fast enough anyway. Soldering guns depend too much on the skill of the operator, and it is all too easy to damage parts while at the same time making poor quality joints. Use a temperature controlled iron with an earthed tip designed especially for electronics, use cored solder designed for electronics, and keep the tip clean with a wet sponge, and you will after a little practice have very little trouble. Not with tip discolouration or corrosion, not with damaging parts, nor with poor quality joints. In my experience, it takes very little time to teach school kids to do excellent work with the right tools. Nearly all master it with their first simple project.

Wiping with a wet sponge normally leaves a smooth shiny solder surface on the tip. If it doesn't, it is because the tip has been ruined by too much heat, cleaning far too infrequently, or using the iron for other purposes such as melting plastic. Or from long use making thousands of joints. 1.122.56.195 (talk) 23:59, 6 October 2013 (UTC)

Agree with the above. Just get yourself a nice temperature controlled soldering iron and a good illuminated magnifying glass stand and you'll produce nice joints and not burn stuff on the tip. Using a soldering gun for electronics is like using a hacksaw instead of a fretsaw for cutting out a pattern. Dmcq (talk) 07:29, 7 October 2013 (UTC)

I question the blanket statement that soldering guns were "never by properly trained technicians doing high quality work on professional equipment" and that they were only used in customers homes. Some joints in tube equipment took a significant amount of heat to get to proper soldering temperature, and a soldering gun could get it hot and get the wire or component lead soldered or unsoldered efficiently without overheating. Also the tv tech generally took the set to the shop if component level troubleshooting and soldering in of new parts was necessary (as opposed to tube replacement or adjustments. It was not reasonable to flip a TV chassis upside down on the customer's living room floor to start soldering in new parts, after hauling in signal generators and other testing equipment. Edison (talk)

You've obviously not worked in TV, radio, and radiogram repair in the 1960's and earlier. I have. After completing university after several years in TV and radio repair I became a profesional engineer. I can assure you soldereing guns were never used by properly trained techs working on professional equipment.

There were a few sets that were notoriously bad from a serviceman's access point of view (I remember the first Philips set available here that was a right cow of a thing), but in general, they were repaired with the chassis in more or less situ in teh customer's home. Different brands had different ways to give you access. On some with metal cabinets (the ones with a fake wood or fake textile covering), you lifted off the entire cabinet from the base plate upon which the chassis sits. On others, the chassis was on a hinged arrangement, with the various leads just long enough to let you (after removing the back) swing it out while it is still operable. Nearly all faults in electronics, then and now, are catastropic, in the sense that the set works well, or it is seriously unusable by the owner, due to a component failing completely (apart from low emission tubes). So nearly all faults were diagnosable by multimeter. I fixed over 90% of sets within minutes in the customer's home, with nothing more than a few hand tools like pliers and screwdrivers. a soldering iron, a multimeter, and experience.

Sets back then were designed somewhat empirically, even by major manufacturers. In consequence each model had its own set of common faults. Got a 1960 to 1964 HMV with an inoperative vertical oscillator? - it's the blocking oscillator transformer open circuit nearly every time. Got a Pope or Radio Rentals ("rent now buy later") with a blank raster? It's the video detector diode nearly every time. A GE 11" portable with compactron tubes? All sorts of weird symptoms were almost always due to the electrolytic can giving up (This set had all electrolytic capacitors in one large can). The 10% that did need a sig generator and/or CRO did get taken back to the shop, as did uncoopertive intermittents (customers get worried when you start banging their set with something hard, and it can take too long).

Customers often really didn't like servicemen taking the set away. The woman would wring her hands and moan "oh!, I was so looking forward to the serial tonight" / "Oh no, my husband has been talking about the game all week" / "My grandchildren are coming to stay with me - I need the TV to keep them amused - couldn't you please please try something and just get it going? I don't mind if the picture isn't perfect. Its for the kids."

And practically the only time you ever needed to do an alignment, the only thing requiring specialist test gear, was when some idiot owner (such as a beginner electronics hobbyist or radio ham) has had a go himself. You could get away with using a soldering gun in TV & radio repair, but only the cowboy types used them. If you worked for a dealer they generally wouldn't allow it. In this country there was an alternative to the gun type - the Scope and Birko brand carbon element soldering irons - they would heat in seconds but they were as bad as the gun types. Every where I worked they were banned.

— Preceding unsigned comment added by 1.122.124.206 (talk) 00:43, 8 October 2013 (UTC)

We can agree to disagree on this. Your personal experience of soldering things into sets in the customer's living room and somehow having good access to the underside of the chassis with the set upright is certainly your experience, but the practice was not universal. Lots of sets went into the shop for bench repair. Edison (talk) 14:53, 8 October 2013 (UTC)

October 7

Fossils in antartica

Are there human fossils or gorilla fossils that have been found in antarctica? How about ruins? — Preceding unsigned comment added by 128.214.166.6 (talk) 09:10, 7 October 2013 (UTC)

No, Antarctica's geographical isolation and glaciation predates humanity's existence. Plasmic Physics (talk) 09:32, 7 October 2013 (UTC)

Elder Things, though—that's a different matter. Deor (talk) 09:59, 7 October 2013 (UTC)

Scarely any more credible that the fictious scribblings on those hellish Archaean organisms is the real Piri Reis map which - if you squint your eyes just so and really really believe - shows a prehistoric Antarctic coast, free of ice, and full, perhaps, of ancient astronauts and maybe Elvis. I mention this only because there are occasional "documentaries" about this, which may linger in the back of one's mind. -- Finlay McWalterჷTalk 11:52, 7 October 2013 (UTC)

Let's take this Q a step at a time:

1) Will there be any fossils in Antarctica ? Yes, because it was once a lush tropical land, in the era of dinosaurs.

2) Will there be any primate fossils ? No, as noted above, because Antarctica was much as it is now during the era of primates, and thus not suitable for primates. However, there might be human mummies, of early explorers, whalers, etc., who died there and were freeze dried.

3) Will there be many accessible fossils ? No, because of the conditions in Antarctica now. Most of it is covered by steadily moving glaciers, making it quite difficult to dig through. There are occasional rock outcrops, though, and excavation could occur there, however, the weather and distance still makes any such mission rather difficult and expensive.

4) Will those fossils be more accessible in the future ? Sure, due to improved technology, perhaps allowing us to scan and find fossils before we start to dig, and also maybe due to global warming, which may melt off some of the glaciers in the way. StuRat (talk) 12:01, 7 October 2013 (UTC)

The British Antarctic Survey website has a database of Antarctic fossils, including some pictures. 'Abundant finds of fossil leaves and wood point to the existence of extensive forestation in earlier geological periods, even to within a few degrees of latitude of the South Pole itself. Dinosaurs, and later, marsupial mammals once roamed across its surface.' AndrewWTaylor (talk) 12:36, 7 October 2013 (UTC)

Note that this doesn't mean the dinos lived within a few degrees of the South Pole, as Antarctica has moved over time, as all the continents have, due to continental drift. StuRat (talk) 12:50, 7 October 2013 (UTC)

See also Geology of Antarctica. Count Iblis (talk) 13:55, 7 October 2013 (UTC)

• Actually the ice cover of Antarctica only dates back about 15 million years, while primates first appeared around 50 million years ago -- so time alone is not decisive here. But Antarctica split off from Africa around 150 million years ago, and its most recent linkages are with Australia and South America. Like Australia, its isolation caused it to never gain land mammals more advanced than marsupials. Looie496 (talk) 16:26, 7 October 2013 (UTC)

• "...OTHER than mammals" may be better language. Words such as "advanced" are problematic when speaking of evolution. And of course the marsupials in Australia continued to evolve after their separation from those places where non-marsupials evolved. HiLo48 (talk) 22:22, 7 October 2013 (UTC)

Yes, the platyrrhine monkeys originated in South America 40 million y/a. It is possible they colonized Antarctica. μηδείς (talk) 16:47, 7 October 2013 (UTC)

What's the likelihood of a disease occuring by means of a french kiss?

What's the likelihood of a disease occuring by means of a french kiss? 140.254.70.33 (talk) 20:47, 7 October 2013 (UTC)

Depends on the disease and the contact. If you've got a specific concern, see your doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:17, 7 October 2013 (UTC)

Oral ecology and more specifically diseases transmitted through Saliva have a partial answer. 23:05, 7 October 2013 (UTC)

Could we eat grass?

Can we process (break it down) cellulose to make it edible for humans? OsmanRF34 (talk) 22:01, 7 October 2013 (UTC)

No. People eat it when they are starving because it is filling, but you cannot survive on it. See Irish potato famine. μηδείς (talk) 22:30, 7 October 2013 (UTC)

Medeis, I mean could we eat it, after we have processed it biochemically (with some enzyme, bacteria or whatever) outside our body. OsmanRF34 (talk) 22:53, 7 October 2013 (UTC)

(ec) Cellulose is broken down by bacteria in our hindgut, but to a very limited extent. Humans have an ensyme that helps break down starch into sugars, so we derive nutrition from starchy foods. However, humans lack an ensyme to break down cellulose into sugars. In general, animals that can derive nutrition from cellulose are either monogastric using Hindgut fermentation, or ruminants. Cellulose structure does not change in cooking, either. If you were to "digest" cellulose outside the body, using some microorganisms such as Weizmann organism for example, you'd end up with sugar or alcohol molecules (some of which have, indeed, substantial nutritional value).--Dr Dima (talk) 22:34, 7 October 2013 (UTC)

The best way to process grass chemically is with a cow. Fermented cellulose yields wood alcohol, which is poisonous. The problem is you either run into toxins or huge waste--otherwise people would be doing it now, rather than feeding it to their livestock. μηδείς (talk) 23:07, 7 October 2013 (UTC)

And using bacteria to break down cellulose is one method of producing methanol now under research and development. The hope is to provide a car fuel by using farm waste, without the downside of making food more expensive, which happens when you make ethanol from corn, or any other food. StuRat (talk) 00:00, 8 October 2013 (UTC)

No, Medeis, the cow is not the best way to process grass. In fact, it takes 20 pounds of grass (or 7 pounds of feed) to make 1 pound of beef; see Environmental impact of meat production. Most of the grass / feed is wasted as CO2 and methane of cow respiration and flatulence. I cannot find numbers for how much sugar or ethanol can be made out of a given amount of straw or grass, but I really hope the ratio is higher than 1:20. (I'm aware it's not an entirely fair comparison, though, as there are large additional costs involved in both beef and bio-ethanol production). In any case, the grass is not meant for eating; it is meant for playing soccer :) . If you want a better intermediate between sunlight and food, try spirulina. --Dr Dima (talk) 00:20, 8 October 2013 (UTC)

Okay Dima, you can recommend eating fried termites rather than some bovine equivalent if you like, but neither does Spirulina 'eat' grass. In the meantime, I will take my grassfedcowproducts. μηδείς (talk) 00:30, 8 October 2013 (UTC)

I don't think that 20:1 ratio is relevant. It's the calories in the 20 pounds of grass that should be compared with the calories in the pound of beef, not the weight. Or perhaps we could compare the protein or some other nutrient. Now, I agree that feeding cattle with food that humans can eat directly is a poor choice, in comparison with feeding that food directly to the people, but in the case of grass, using animals to convert it into something edible to humans, like milk or meat, isn't a bad choice. Of course, we can choose to grow food crops instead of grass, in some places, but not all places where grass grows are suitable for other crops. StuRat (talk) 00:27, 8 October 2013 (UTC)

You both are certainly right in that beef provides more calories (than grass) and tastes much better than the alternatives; I am not arguing for switching from eating steaks to eating sugar, ethanol, or cyanobacteria :) I do however think that, as far as the answer to the original question goes, fermentation outside the cow is a more promising method of cellulose processing than fermentation inside the cow. --Dr Dima (talk) 00:56, 8 October 2013 (UTC)

Grass carp are much more efficient than cattle for converting cellulose to human-edible nutrients. Roger (Dodger67) (talk) 09:09, 8 October 2013 (UTC)

People might have a beef with that and carp about your plan. StuRat (talk) 14:03, 8 October 2013 (UTC)

Can we process (break it down) cellulose to make it edible for humans?

Yes, in theory. And there are rudimentary efforts to develop an efficient chemical process to convert cellulose to starch for human consumption, as discussed in this paper (non-technical overview: Let Them Eat Wood!). The process though is currently wildly uneconomical:

Zhang estimates that, given the current price tag of the enzymes that his team used, it would cost about $1 million to turn 200 kilograms of crude cellulose into 20 kilograms of starch, about enough to feed one person's carbohydrate needs for 80 days.

Also note that while using cellulose as a food substitute is improbable in the near future, cellulose is already used extensively as an "external energy source" after conversion to Cellulosic ethanol. Abecedare (talk) 01:14, 8 October 2013 (UTC)

I think "extensively" is a bit of an exaggeration when talking about Cellulosic ethanol. Rmhermen (talk) 01:39, 8 October 2013 (UTC)

You are right. I should have said that it is much closer to mass commercial exploitation than cellulose-derived-food but had a brain freeze at some point. :) Abecedare (talk) 02:37, 8 October 2013 (UTC)

Yes, I had mentioned this above. Note that this could increase food production, indirectly, if we return to using corn exclusively as food and cattle feed, rather than to produce ethanol. StuRat (talk) 14:01, 8 October 2013 (UTC)

Many animals besides cattle convert cellulose into tasty meat, and some produce milk and textiles as well. Rabbits eat a lot of grass and other plants and need less management than cattle. I have several in my yard most days managing their own affairs quite well. Edison (talk) 14:36, 8 October 2013 (UTC)

Brain wrinkles

Why are our brains wrinkled? The standard explanation is that it's to do with size- but this doesn't make sense. Doesn't volume matter more than surface area for the brain? Is there some kind of neural activity that can only take place on the surface? 68.0.144.214 (talk) 23:11, 7 October 2013 (UTC)

[18] Plasmic Physics (talk) 23:18, 7 October 2013 (UTC)

Completely SWAG here: more surface (which implies less volumen), and that's helpful because it can get more glucose or oxygen. OsmanRF34 (talk) 23:29, 7 October 2013 (UTC)

• The appropriate (if not helpful) articles here are gyrus and sulcus. The size explanation does make sense, you just have to see it from an evolutionary/developmental point of view. It's specifically the outer layer of the brain, the neocortex, which expanded the most during human (and other higher mammals) evolution. The embryonic development here is important, like all mammals, the cortex develops in a flat, layered structure during early embryogenesis. The thickness and order of these layers is crucial for the correct functioning of the cortex later on. This is why you can't just make them thicker, rather than fold them up. In lissencephalic animals, the cortex remains flat. In humans however, by the 5th month, the cortex grows too large to remain in a flat layer, in essence it outstrips the growth of the underlying deeper brain structures. Hence the giri and sulci, just a means to fit an excessively large neocortex in a finite volume of skull, without distorting the organisation within the cortex. Fgf10 (talk) 23:39, 7 October 2013 (UTC)

• Surface and volume both matter, but in different ways. The cerebral cortex consists of gray matter on the surface and white matter underneath. The cell bodies of neurons are almost entirely in the surface layer of gray matter, and there is no way of making that layer thicker without massively changing its architecture. So the only simple way to increase the number of neurons is to increase the surface area. The white matter is mainly filled with axons that connect neurons to each other. So, an increase in connectivity would generally imply an increase in white matter, and therefore an increase in volume. The factors that result from all this are pretty complex to work out, but if you would like to read more, you might look at http://www.pnas.org/content/97/10/5621.full for a starting point. Looie496 (talk) 23:42, 7 October 2013 (UTC)

Brains of several types of mammals, with labels in French

• How do you fit a cloth napkin into a wineglass? μηδείς (talk) 00:33, 8 October 2013 (UTC)

Make the napkin smaller than the wineglass, of course. That rationale isn't convincing unless you explain why the napkin needs to be larger than the wineglass. For the cerebral cortex the answer isn't obvious, because the general principle is that the cortex of small-bodied animals such as a rat tend to be smooth, whereas the cortex of large-bodied animals such as a whale or elephant tend to be very convoluted. Looie496 (talk) 01:17, 8 October 2013 (UTC)

Does it not occur to you that making the neocortex smaller means making the processing area less powerful? The chimp's cortex is about 1/4 the surface area of ours, and the difference is largel due to wrinkling. Human brains have a mechanically limited volume, and folding allows more surface within the same volume. The surface structure of the cortex is vital. Jeff Hawkins covers this in On Intelligence. This is all comparative mammmalian intelligence 101, not speculation. Carl Sagan covered it way back in his Dragons of Eden. μηδείς (talk) 01:53, 8 October 2013 (UTC)

Human brain addresses the folding and gives the reason for it. As Fgf10 implies, we don't seem to have any one article that addresses this directly, fully, and concisely. μηδείς (talk) 02:49, 8 October 2013 (UTC)

Of course packing more surface area into a given volume is part of the story, but a full understanding would mean being able to explain the differences in convolution patterns for various species, as in the picture I've added. And that's not so easy to do. Looie496 (talk) 03:59, 8 October 2013 (UTC)

That PNAS reference is really a nice exposition, except.... it argues that a simple scaling law requires the amount of white matter to grow at a 4/3 power law faster than the amount of grey matter. Which means that if an animal were large enough, the existing grey matter ought to be stretched taut, doesn't it? Also, the humans are right dead center on the line they draw through all the species. [19] Which leads me to think that the convolutions actually have nothing at all to do with the grey/white matter ratio, at least within the existing range of sizes; they incorporate both white and grey, as we know from images. And yet... well, something has me badly confused on this point. Wnt (talk) 04:03, 8 October 2013 (UTC)

Hmmm, some more clues: Echidna helpfully points out that its brain is far more folded than that of the platypus, with a thinner grey matter layer; and lissencephaly mentions that some persons with the condition have 'near normal intelligence'. It represents a failure of neuronal migration, but with relatively trivial causes (viral infection). So what we're looking at here is a reorganization of the grey matter to make it thinner (but wider) that somehow is advantageous, which makes it fold up. Wnt (talk) 04:14, 8 October 2013 (UTC)

OK, [20] is a good one. It explains the conventional justification for increased folding with increased size: the head can't scale at the same rate as the body and still be feasible to hold up. So there's this pressure to have a number of grey matter cells proportional to the cells (and presumably sensory cells, muscle fibers, etc.) of the body, versus this other scaling law of grey/white matter. The result is that there are lineages that undergo lissencephaly with miniaturization (mice, marmosets). Then there are sirenians, which apparently have a tendency to this, especially manatees (but then again, those critters are ... not persuasively functional neurologically, as critters go). I didn't quickly find information in NCBI for the claim that lissencephalics can have normal intelligence; I found the claim from Wikipedia at [21] but it isn't clear in this context whether this refers to mild losses of folding as well as mild losses of intelligence. I'll leave this point open for now. Wnt (talk) 04:28, 8 October 2013 (UTC)

October 8

Going to Space

A small group of us are getting together to try and launch something into space, by any means necessary. So far, we seem to have settled on the idea of getting a big helium balloon, but as far as I can tell, that'll only get us 20 miles or so up, rather than all the way into actual space. I'm wondering if there's any better alternatives, maybe a stronger balloon, perhaps if it had a lower pressure of gas to survive the inevitable expansion, perhaps if we could launch a rocket from the balloon once we're up in the thin air there, are any of these ideas actually feasible? Has anyone managed such an amateur launch all the way across the boundary of space before, and how did they do it?

213.104.128.16 (talk) 11:24, 8 October 2013 (UTC)

Outer space is, by definition, a vacuum. No matter what you fill your balloon with, or what you make it out of, it will never be lighter than nothing, so you can't float into space on a balloon. You can launch rockets from balloons and aircraft, but it's only of marginal benefit. Do you really just want to get to space, or to orbit? Of those, only orbit is particularly useful, and to do that you need to get orbital speed, which is thousands of mph, something which can only be attained (with current technology) with a substantial rocket. -- Finlay McWalterჷTalk 11:33, 8 October 2013 (UTC)

Space is, by definition, 62 miles high, where air pressure is low enough to prevent winged aircraft from flying. The aim is to cross that line with some sort of altimeter and return with evidence. Getting into orbit can wait for a later project. 213.104.128.16 (talk) 11:49, 8 October 2013 (UTC)

See rockoon, which outlines launching rockets from balloons. The benefit is off course that you don't spend fuel getting up the first few thousand meters, saving weight and cost. WegianWarrior (talk) 11:57, 8 October 2013 (UTC)

See the Brooklyn Space Program, which used balloons to send an iPhone into space, recording the entire trip. For inspiration, see this amazing video of the iPhone's journey to space and back down to earth, with pretty awesome footage of both outer space and our planet on the way down. Zunaid 12:48, 8 October 2013 (UTC)

I support the concept of a rocket launched from a balloon as the best way to get into space and then come right back down. However, you do need to be careful where you do this, as a plane might crash if it runs into the balloon. So, you want to do this far from commercial routes, and also ensure that the balloon collapses and falls right down after the rocket is launched, rather than floating around posing a continued hazard to navigation.

Also, you might want to use hydrogen rather than helium. It's cheaper and has better lifting power. It is flammable, but as this is an unmanned craft, the risk is minimal. StuRat (talk) 13:52, 8 October 2013 (UTC)

Risk is minimal once launched. If you use hydrogen you should certainly consider the risks when filling the balloon, as well as storage and transportation. -- Q Chris (talk) 14:55, 8 October 2013 (UTC)

The current record is 53 km, so just into the mesosphere. Perhaps a two stage balloon would work better. You can put a very small amount of hydrogen gas in a huge balloon so that at sea level it isn't inflated at all. This is then carried folded up on board a helium balloon. The folded balloon is held firmly in its shape to prevent it from expanding as the balloon rises and air pressure drops. Then when some target height is reached (say 30 km), the folded balloon is let to expand. The volume increases by itself because of the low pressure, it's size will be much larger than the balloon that carried it at 30 km. At that height the pressure in the original balloon is no longer equal to the air pressure, but the big balloon won't be completely inflated, the pressure of the hydrogen gas inside will be the same as the atmosheric pressure. This means that the big balloon will be able to rise a lot higher than the original balloon. Count Iblis (talk) 14:33, 8 October 2013 (UTC)

What nonsense is this? A balloon, filled with a lighter than air gas, prevented from expanding, is just harder to lift than one that isn't. 1.122.124.206 (talk) 14:48, 8 October 2013 (UTC)

In fact slightly harder as you would not get the benefit of the increasing buoyancy of the balloon as it expands. -- Q Chris (talk) 14:56, 8 October 2013 (UTC)

And the Kronig-Causius equation (for any gas, the volume occupied is a function only of the number of molecules, teh temperature, and the pressure) shows us that a balloon that allows the pressure inside to equall the pressure outside will, if boyant at any given altitude, will be boyant at all altitudes. So no point in having two different balloons. 1.122.124.206 (talk) 15:01, 8 October 2013 (UTC)

No, that's not the point here. You have to release the constraints in the stratosphere, it can't be used at low altitudes, because the aerodynamic forces due to the varying wind speeds over its length will be very large. Count Iblis (talk) 15:11, 8 October 2013 (UTC)