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July 3

Succulent plant ID and advice please

Hello everyone. Awhile back I bought a dumpy little succulent plant from a street vendor and to my surprise it has done really well at home. I have turned its tray many times, but have ended up with a sprawling beast somewhat reminiscent of a grasping hand. [[1]] [[2]]There are now also plantlets budding at the base of the plant. I would like to know what kind of succulent this is, and what I can/should do to ensure its safe further growth. Can these be propagated via cuttings, for example? Thank you. The Masked Booby (talk) 00:34, 3 July 2012 (UTC)

I believe that's Crassula marnieriana (the picture on our page certainly doesn't look much like your plant, but cf. the image here, for instance). Deor (talk) 02:18, 3 July 2012 (UTC)

My theory is, "if it ain't broke, don't fix it". However, it will soon outgrow that pot, so you might want to transplant it into a larger pot. I'd take the entire root ball, including those other plants, if the roots are intertwined, and plop it all into the larger pot, so your plant is now centered, and fill in the empty space with more of the same soil you are using. StuRat (talk) 06:27, 3 July 2012 (UTC)

Crassulas generally do well in spaces where their roots are slightly confined, giving them too much space may cause watering problems and root rot. They come from areas with a hot sunny climate so the best you could do for your plant is get it into some sunlight (the sempervivums in the pot would also benefit). If they get enough sun they will get nice pink edges to their leaves and even flower. Crassulas generally are tough plants that can be propagated easily. See here for more good info and pictures Richard Avery (talk) 08:00, 3 July 2012 (UTC)

How does extra space cause watering problems and root rot ? StuRat (talk) 16:43, 3 July 2012 (UTC)

Because when the soil is watered the plant does not take it all up sufficiently quickly and there is a much greater risk that the roots will saturate and rot. this is a succulent that has developed to live in harsh and arid surroundings and will not like to be mollycoddled with lots of new soil. My experience has shown that people tend to kill plants with "kindness" not so much with neglect, especially crassulas who love neglect - but love sunshine even more. Richard Avery (talk) 19:04, 3 July 2012 (UTC)

Why can't you put it in a larger pot, but continue to water it a much as before ? StuRat (talk) 04:22, 4 July 2012 (UTC)

Yes, you can. If you are an experienced plant owner then that's fine, but I was just giving a little warning about a common problem among less experienced plant carers. Richard Avery (talk) 07:01, 4 July 2012 (UTC)

Why fungi was differ of green plant?

Why fungi was differ of green plant? Can you give me main points thanks. — Preceding unsigned comment added by 175.137.136.85 (talk) 00:46, 3 July 2012 (UTC)

Please see fungus and plant. They are completely different kinds of organisms, although they are commonly and mistakenly believed to be closely related. If you still have questions after reading those, feel free to come back and ask them. Someguy1221 (talk) 00:48, 3 July 2012 (UTC)

It's enough to read fungus, which covers the differences specifically. Looie496 (talk) 01:02, 3 July 2012 (UTC)

Just go to any party, where it's simple to tell the diff between a fun guy and the common wallflower. StuRat (talk) 06:30, 3 July 2012 (UTC)

You may also be interested in mycorrhiza, hypha and actinomycetes. ~AH1 ^(discuss!) 17:43, 3 July 2012 (UTC)

ID Please (Cixiidae)

I suppose this is a Cixiidae. Could you able to suggest the species or genus, please. Thanks, Jee Jkadavoor (talk) 08:10, 3 July 2012 (UTC)

You'll have more success if you tell people where you took it. In this case I can see in the description it is from Kadavoor, Kerala, India. If no one here can help, then try WT:INSECT or http://www.whatsthatbug.com SmartSE (talk) 17:50, 3 July 2012 (UTC)

Thanks; I got one suggestion at WT:INSECT -- Jkadavoor (talk) 09:23, 6 July 2012 (UTC)

Does swimming make you lose muscle mass?

I've been hearing by a lot of very sure sounding people that if you're a body builder and you start swimming your muscle mass will shrink. From my medical knowledge I believe that only if you do very intense cardio you will lose muscle mass and swimming will not reduce muscle unless you do very intense long periods of it. Am I wrong? Bastard Soap (talk) 11:37, 3 July 2012 (UTC)

The answer depends on a number of factors that are not presupposed in your question. I'm presuming, for examples, that by "lose" you mean that your overall mass will decrease, but not so much as a result of the swimming itself, but rather from the redirection of your priorities in working out (that is, that you could maintain your current mass or even improve it if you stuck to your current routine). In this respect, yes, it may be that you would lose some overall mass depending on how much you re-prioritized your exercise. That being said, as a body builder you probably are already quite familiar with the concept that you reach a point of diminishing returns with repetitive motions, so supplementing your workout with swimming might not cause you to lose overall mass at all, or plausibly to put more on, since it is a workout that, almost more than any other, works a broad array of muscles. But your mileage will vary considerably with the amount of time you decide to put in, needless to say. Also note that there is difference between overall mass and the characteristic bulk of a bodybuilder's physique. In any event, if you are going to start doing any form of intensive cardio after a long period of being committed to anaerobic exercise you should take things slowly at first and ideally consult a doctor -- for the obvious safety reasons and because he'll also likely be able to provide you assistance in meeting your training goals. Let me know if this is more basic than you intended and I'll go into further detail. Snow (talk) 13:19, 3 July 2012 (UTC)

As long as you are getting adequate nutrition, I can't see why intense cardio would cause a reduction in muscle mass, all else being equal (as Snow Rise says, if you are doing cardio instead of other exercise, then it might, but that's just because of a reduction in the other exercise). --Tango (talk) 15:08, 3 July 2012 (UTC)

Agreed. Specifically, if you were concentrating on a small number of muscles in your previous workout (bodybuilders with a massive chest and tiny legs come to mind. ), and then switch to swimming, you will lose those few large muscles and get more of an even muscle tone. StuRat (talk) 16:51, 3 July 2012 (UTC)

Let's say you keep your training program with weights and add swimming at a rate that isn't too intensive, it will only help you build muscle right? Snow Rise if you have anything more to add feel free Bastard Soap (talk) 17:51, 3 July 2012 (UTC)

That's correct; as far as I know, there is no major metabolic reason why swimming, or any cardio, would cause you to retain less mass, if it were just added on top of your existing routine. With regard to bodybuilding (or any kind of strength training), there are two different kinds of muscle tissue growth at work: muscular hyperplasia (the increase in the number of cells in the relevant tissues) and muscular hypertrophy (the increase in the size of the cells in those same tissues, since, unlike many other forms of tissue, this can be made quite variable through exercise). The interaction between these two different types of muscle development, and other factors, are also probably known to you already through the concept of "bulk vs. tone"; in general, the extra mass you gain from swimming will tend towards the "toned" end of the spectrum, owing to the fact that you will be "recruiting" (as exercise physiologists say) a larger number of muscles per motion, but stressing most of them far less (again, per motion) towards top exertion and because certain types of muscle respond differently in terms of growth to different exercise. Bodybuilders often exploit this formula to tailor their workouts by either doing a higher number of reps with lower weight for tone or a lower number of reps with higher weight for bulk and the same principles will apply here, only, since the level of resistance is determined only by the water and your muscles leveraging off of each other and the rest of your body (as opposed to free weights where you can change the resistance), the overall trend will be towards the muscle added to be "toned". This can be controlled somewhat by choosing your swimming motions and is also variable depending upon how fast as opposed to how long you choose to swim, your nutrition, and your unique metabolism -- but again, the overall trend will be toward toned muscle in the new mass. Note that there are other potential benefits to adding muscle in this fashion, including increased muscle stamina, flexibility and even strength; bodybuilders are typically strong, of course, but not always as strong as they look, since they tend to prioritize hypertrophic exercises that promote bulk vs. those that provide strength (this is why the fields of bodybuilder and weight-lifter are not automatically interchangeable). This type of exercise also promotes strength by making sure that the inter-dependencies between muscles are strengthened as well, such that they grow together and there's less occurrence of a "weak link" (an underdeveloped muscle group which inhibits peak performance/efficiency of another in a specific movement by not being able to pull it's own weight, so to speak ;). There's also the fact that incorporating more muscles means you will be developing a broader base of muscle tissue types. Hope that helps - though, not to sound like a broken record, but all radical changes to your exercise routine should be broached with a physician, even if you think of yourself as being in good health! Snow (talk) 21:00, 3 July 2012 (UTC)

These Olympic medallists are primarily swimmers. Most guys would envy their muscle mass. HiLo48 (talk) 22:53, 3 July 2012 (UTC)

As Tango wrote above, you have to make sure you eat enough when you do a lot of cardio exercise. E.g. I exercise 35 to 40 minute per day, I do quite heavy cardio exercise, and I really need to eat about 3500 Kcal/day just to keep my weight of about 59 Kg stable. A more extreme example is Michael Phelps' diet. Count Iblis (talk) 01:06, 4 July 2012 (UTC)

addmision

Hello.Good evening.I want to register in your university but I am a muslim woman.Can I accept with your university? Thank you of your consideration. — Preceding unsigned comment added by 199.127.102.196 (talk) 16:34, 3 July 2012 (UTC)

Yes. Just about any college or university in the West will be open to people of all religions and genders. The only case of religious exclusion I can think of is a seminary, where people train to be Christian or Jewish missionaries. There may still be a tiny number of single-sex education universities, but those are more likely to be female only, in any case. Depending on how conservative your religious beliefs are, you might prefer an all-female college. StuRat (talk) 16:53, 3 July 2012 (UTC)

Just thought id point out-there are no jewish missionaries I know of-at least among the orthodox community (I dont know about reform). you may be thinking of talmudical colleges which are completely different. — Preceding unsigned comment added by 86.148.117.79 (talk) 20:35, 4 July 2012 (UTC)

Messages such as this mean that a person tried to Google for a university, found Wikipedia as the first link and followed it thinking it is the web site of the university, followed the "Information" link that appears and thereby got taken to the Ref Desks, and asked a question thinking she was asking it of an official representative of the university. It is useless to answer them. Looie496 (talk) 17:38, 3 July 2012 (UTC)

A polite answer is useless? OsmanRF34 (talk) 11:56, 5 July 2012 (UTC)

(edit conflict) Are you asking about Wikiversity? If so, then of course you can join - anyone can. It's not a real university though... SmartSE (talk) 17:39, 3 July 2012 (UTC)

[Edit conflict x 2]Although Wikipedia is not a university, we do have a sister project over at Wikiversity. For higher education schools in the Miami area, try Universities and colleges in Florida. ~AH1 ^(discuss!) 17:40, 3 July 2012 (UTC)

This question is positive feedback for us! Count Iblis (talk) 17:57, 3 July 2012 (UTC)

And who wouldn't want to learn at the feet of such sage and knowledgeable personages? :) Snow (talk) 04:36, 4 July 2012 (UTC)

Just a word of advice, if you (the original poster) are planning on applying to a Western university: do not, under any circumstances, mention religion in a conversation with a university representative. This isn't because Muslims are not welcome (discrimination based on religion is illegal), or that the university will necessarily be biased; it's because religion is simply not an appropriate topic. In both Canada and the US, for example, it is outright illegal for employers to ask candidates about their religion. I don't know if the same applies to admissions interviews, but there's certainly a strong cultural aversion against it. --140.180.5.169 (talk) 02:41, 4 July 2012 (UTC)

At least in some Western countries, however, while there is no discrimination on religous grounds (Moslem women are welcomed at the Australian university I (an Australian male) went to, there are some minor practical issues that you probably should be aware of. Generally, Australian universities make it a condition of graduation that you hold an Australian Senior First Aid certificate, or an equivalent. Since most undergraduates do not have it, classes are run on campus, and this involves practicing on each other in a mixed sex class (bandaging, placing inert buddy in coma position, feeling for pulse at wrist, neck & ankle, feeling ribs for breathing, etc). This is all very ho-hum boring for westerners, but moslems may be uncomfortable. Usually, the university is happy to run an all-female class for first aid or accept a first aid certificate from your home country. I did engineering - this involves getting assignments to be completed in groups of 4 to 6, generally for a week or 2. The assignments are designed so that there is too much work for one person, so the group must coordinate and cooperate. Naturally, your predominantly Australian male class mates will want to hold assigment coordination meetings, and joint work ssesions, at places convenient to the greatest number - this may be in a University library room booked for the purpose, someone's house, or even, sometimes, a nearby coffee house. So you need to be comfortable around males. When I was at uni, a couple of moslem girls brought chaperones along - that's cool, we understood. When I've visited moslem friends, their female folk did not come into the same room, per their custom. Westerners, especially Australians, don't work that way - all of both sexes will expect to be introduced, and any may offer you food and drink. None of this should distress you - the predominant reaction of western male (& female) students will be to adjust to your needs and look after you, not distress or embarras you. In some moslem countries (eg Iran), if you are offered sweats to eat, it means "please eat and then leave". Again, Westerners are different. If they offer you extra food, it means they like you, you are not required to eat it if you don't want to, but please don't leave yet. If you drive a motor vehicle (almost a necessity in Australia unless you live in a campus college or live nearby), and you are veiled, the police may require you to show your face for identification purposes - this is the only circumstance where you would be required to do so. If you come from a couple of countries, in particular Iran and Afganistan, when you return home after completing your degree, your experience may be misunderstood. Ratbone124.178.52.55 (talk) 03:38, 4 July 2012 (UTC)

If I was offered sweats to eat, I'd certainly take the hint and leave. Offer me sweets, on the other hand, and I'd never leave. :-) StuRat (talk) 04:31, 4 July 2012 (UTC)

• Let me try again; my previous explanation obviously did not work. It frequently happens that people who have no idea what Wikipedia is go to the web looking for the web site of a university or company or something, wanting to ask a question, and end up on the Wikipedia Reference Desks. If you are interested, you can work out how that comes about: google for a name such as, say, "University of Denver". Follow the link to Wikipedia, which is always near the top, and imagine that you think it is the University of Denver's web site. Try to figure out how to ask a question -- you will see that you naturally end up on the Reference Desks. When this happens, it is very likely that the person will never come back, because they won't understand how they got here in the first place, but if they do, the only useful answer is to explain that this is not an institution's web page, it is an encyclopedia. Trying to answer the question is almost always a waste of time. Looie496 (talk) 15:40, 4 July 2012 (UTC)

We read your first post when you posted it. I acknowledge your superior experience, and, now that I have tried it, I agree with what you say using Googling U. of Denver as an example. However, since the OP may or may not have a good command of English (I notice that many posters do not) it is possible she meant to ask "Is there any issue with me enrolling in an english (ie western) university. Also, once she realised Wikipedia is not a university, she may seek a western university. She most likely intended to ask the university the same question - not necessarily the best approach as 140.180.5.169 said. So 140.180.5.169 was being helpfull. Once 140.180.5.169 posted, the post became searchable in archives (when the day's posting are archived), and may be discovered by another person looking for issues with enrolling at a western university. Not that likely perhaps, but definitely possible. That's why I made the next post. I agree the OP probably won't be back to look at the answers (either she won't know how she got there, or has since realised her mistake), but she might realise that googling the same phrase again will give the same result, and the info may be usefull to others. Ratbone124.182.137.18 (talk) 16:07, 4 July 2012 (UTC)

We get many such misplaced posts at Wikipedia:Help desk. {{Astray}} was created for the purpose. PrimeHunter (talk) 22:07, 4 July 2012 (UTC)

July 4

Pollination

How pollen get to the stigma? — Preceding unsigned comment added by 175.137.136.34 (talk) 00:39, 4 July 2012 (UTC)

Please read the article pollination. It should answer your question pretty thoroughly. Evanh2008 ^{(talk|contribs)} 00:43, 4 July 2012 (UTC)

Or watch Grease 2, in particular the biology lesson. Or just Google the lyrics. Mitch Ames (talk) 11:15, 4 July 2012 (UTC)

Oddly enough, that song isn't even the best reason to never watch that movie... Evanh2008 ^{(talk|contribs)} 11:30, 4 July 2012 (UTC)

Artificial Insemination for "Lonesome George"?

The recent death of the last Pinta Island tortoise, Lonesome George, resulted in the extinction of this sub-species of Galapagos tortoises [here]. Attempts to mate him with related species did not work, as Lonesome was not really interested. I am wondering why Artificial Insemination was not used, as it is in just about any species which have a commercial angle for humans.

Then again, I am not really sure how AI works (Same acronmy as Artificial Intelligence!). Is it just a case of masturbating the animal with electricity? If so, can I buy such a device? Maybe with tortoises, it would just take too long. Would they let him look at some piccies of really horny she-tortoises while they did it?

I've heard that men in comas have "donated" sperm via this procedure. It gives the term "manual work" a whole new dimension. Seriously, though, how DOES AI work, and could it have been used in Lonesome George's case? Coz if it could, we could all have these lovely creatures home as pets - there would be zillions of 'em! Myles325a (talk) 09:04, 4 July 2012 (UTC)

It is very difficult to masturbate reptiles. I hope they froze his testes before the spermatocytes died. 75.166.192.187 (talk) 09:55, 4 July 2012 (UTC)

You say it is very difficult but how exactly do you masturbate a reptile? SkyMachine ⁽⁺⁺⁾ 11:25, 4 July 2012 (UTC)

The question remains; once he's dead why not just operate to extract some semen? Or was he just too old to produce it?--Shantavira|^{feed me} 11:48, 4 July 2012 (UTC)

As all reptiles have their equivalent of a penis (their hemipenes) totally inside, and only extend it outside when sexually excited, and we humans don't look or smell like a sexy female reptile (and in most cases would have little idea what the species courtship procedure, if any, actually is), getting a male reptile excited would I think be just about impossible, let alone getting him to come...

Hey, we are the "Yes We Can" people, ain't we? We could derive some of that wonderful pheromone reptile fragrance, and rub it all over, and string some crocodile handbags on various parts of our anatomy or something. It's not that hard. Myles325a (talk) 04:35, 5 July 2012 (UTC)

...There may be some injectable homone method possible, but I doubt that it has been studied adequately, or of it has, you probably can't buy the hormone. Wickwack120.145.155.9 (talk) 12:02, 4 July 2012 (UTC)

Your premise is in any case incorrect. Lonesome George was "interested" and did mate with two female companions of a closely related sub-species, who laid (if I recall correctly) 3 clutches of eggs between them, but the eggs proved to be infertile. AI might well have had the same negative result. {The poster formerly known as 87.81.230.195} 84.21.143.150 (talk) 12:28, 4 July 2012 (UTC)

Now I am really wondering if the rangers and scientists at least bothered to take a flesh / sperm sample for future studies. Even if we can't clone Lonesome now, or use his sperm now, we might be able to do so in a few years time. Anyone know if this was done? Myles325a (talk) 04:35, 5 July 2012 (UTC)

• Yes you can - do electroejaculation on a turtle. [3] Wnt (talk) 15:51, 5 July 2012 (UTC)

OP myles325a back live! Ahh, I looked up that article, and it specifically notes procedure is used for "male mammals". There is no reference anywhere there that it has ever been used, or indeed could be used, on reptiles. Although now I see how it works in general. Electric dildo up the bum gives prostrate a good charge. Sounds awfully kinky, or am I just being immature about this? Presumably that is the raison d'etre for gay sex. Myles325a (talk) 05:06, 6 July 2012 (UTC)

• The soft approach, however, seems less productive. [4] Wnt (talk) 15:52, 5 July 2012 (UTC)

OP myles325a Back Live Part II. Sorry, did someone edit out summink here, or have I just had an attack of the obtusenesses. What is "the soft approach", and why does it seem "less productive"? Myles325a (talk) 05:06, 6 July 2012 (UTC)

• Figures. They were too cautious ever to do it. [5] Wnt (talk) 15:55, 5 July 2012 (UTC)

OP myles325a Back Live Part III: The Adventure Continues. Wtf! Am I getting the old-timers' disease? Too cautious to ever do what??!!Myles325a (talk) 05:06, 6 July 2012 (UTC)

Higgs boson

in this context what is the Golden Channel? Kittybrewster ☎ 09:08, 4 July 2012 (UTC)

The CMS Golden Channel is the pp→H→ZZ^(*)→4μ decay branch per [6]. 75.166.192.187 (talk) 09:50, 4 July 2012 (UTC)

(edit conflict) The Higgs boson cannot be detected directly because it decays too quickly. Therefore the various detection experiments actually look for the products that would result from one or more ways in which the Higgs boson could decay. Each of these decay "modes" is called a channel. Even if the right decay products with energies, directions etc. in the right range are observed, there is a chance that they could have come from some other interaction. So it may be difficult to separate the decay events that we are interested in (the "signal") from other random events that we are not interested in (the "background"). The best "channels" to search are the ones where there is most signal and least background, or which can be "cleaned" to reduce the background (all this terminology comes from signal processing); an especially good search channel is called a "golden" channel. The "golden" channel for Higgs boson detection is decay mode H -> ZZ* -> 4 leptons - see here for more details. Gandalf61 (talk) 10:00, 4 July 2012 (UTC)

apricots

Do apricots ripen on the tree or should theu be picked when not quite ripe? — Preceding unsigned comment added by 37.102.230.28 (talk) 14:21, 4 July 2012 (UTC)

Judging by what they sell in supermarkets, I would say they pick them before they ripen. 92.80.7.143 (talk) 14:22, 4 July 2012 (UTC)

Ideally the later you pick them the better, but the later you pick them, the harder they are to handle. It comes down to a tradeoff. The best test, for apricots and other types of stone fruit, is to sniff one. If it smells like an apricot, it will probably have good flavor. If it smells like nothing (the usual case, unfortunately), it will probably taste like nothing. Looie496 (talk) 15:30, 4 July 2012 (UTC)

Simple answer to the question - they WILL ripen on the tree. In my neighbourhood, that opens the risk of the local birds enjoying more of them than I do, but they are better fresh from the tree. HiLo48 (talk) 17:20, 4 July 2012 (UTC)

Slightly underripe is best for jam. A French friend made apricot jam for me and added slivered almonds soaked in brandy. Mmmmm. Itsmejudith (talk) 20:53, 4 July 2012 (UTC)

Are you sure that what you thought were almonds, weren't in fact the kernels from the apricot stones? I have a recipe for apricot jam which involves cracking the apricot stones, removing the kernels, soaking them in brandy and adding them to the jam before potting. --TammyMoet (talk) 09:39, 5 July 2012 (UTC)

Hmm. My understanding is that apricot kernels contain significant amounts of cyanide. Looie496 (talk) 16:14, 5 July 2012 (UTC)

Apricot kernel. 86.143.135.49 (talk) 21:41, 5 July 2012 (UTC)

Mixing old and new batteries

Resolved

1. All electronic devices discourage mixing old and new batteries. Can somebody please explain why?
2. I just modded my Wii sensor bar to USB powered. The sensor bar takes 7.5 volt from the Wii, and it refused to run with 5 volt from the USB 2.0 port. So I had to add a 1.2v battery and it ran fine. The battery is drained over time, I know, but the power from the USB port remains the same. The circumstance is very similar to mixing old and new batteries. Is it harmful to the battery and the device? FYI, the battery I use is rechargeable. I'm not sure if there is any difference between the rechargeable and non-rechargeable batteries, but my thought is that the USB port charges it when its capacity is running low.

-- Livy (talk) 15:20, 4 July 2012 (UTC)

With dry cells (carbon-zinc, alkaline, etc), the reason why you are advised not to mix old and new is because the stronger cells will reverse-charge the weaker cells. This takes the cells outside the design parameters of manaufacture and the cells may then leak corrosive substances, damaging the electronic device. With rechargeable cells, generally and sort of mis-match (age, type, size, etc) will run the risk of reverse charging the weaker units and this will damage them. Also, especially with dry cells, their internal resistance rises as they are discharged. The stronger cells must force current thru this resistance, which means you get less usable energy out of the good cells than you should. Putting a cell in series with the 5V supply of a USB port does not seem very wise, as again you are taking the port outside design parameters. When the computer/usb port is powered down, the cell will discharge back into the usb port and may damage it. A boost switchmode regulator should be used if you need to increase voltage. The USB port will NOT recharge a series connected cell - the cell, if connected so as to increase the voltage, is connected the wrong way round for recharging. Keit120.145.155.9 (talk) 15:46, 4 July 2012 (UTC)

I always unplug the sensor bar from the USB port after playing, before turning my computer off. Is there any other potential risk for the sensor bar, the battery, or the computer? -- Livy (talk) 19:16, 4 July 2012 (UTC)

Assuming you are using a dry cell, and you do disconnect before powering down, there is no additional risk provided that you never allow the cell to become flat. If it becomes flat, the reverse charging from the USB port may cause the cell to swell up, possibly preventing you from getting it out of the holder. If the cell/battery is a rechargeable, you run the risk of over-reverse-charging, which will certainly damage the cell and may cause venting of the electrolyte. While you may intend to always disconnect before turning your computer off, you may forget. Be aware that under certain configurations, USB ports may be depowered when the computer is in sleep mode. If the electronic device becomes shorted, the cell is now directly across the USB supply, and if a small cell, could in theory explode, though this is not very likely for common cell types (Li-ion excepted). Using a cell in this way is not very wise. Ratbone124.182.173.101 (talk) 01:20, 5 July 2012 (UTC)

I know it is not wise, but I suppose I do not have much of a choice. If I had not did it, I would have disassembled the sensor bar and removed some IR LEDs to make it working, but the Wii Remote accuracy would reduce. Currently I am using a rechargeable battery. Can you please explain the "over-reverse-charging" thing? I do not know much 'bout physics so you shouldn't need to go into technical details. I just want to know when it happens and how to avoid it. Thank you. -- Livy (talk) 03:57, 5 July 2012 (UTC)

There's 2 parts to this - reverse charging, and over charging. I'm an electronics engineer, not a battery chemist, but here's my understanding:-

First, reverse charging:- If you take a fully charged cell, it will provide a voltage across the terminals, with the correct polarity. As the cell is discharged, the voltage falls, slowly at first, then increasingly rapidly. For equipment functional purposes, and to avoid cell damage, industry considers cells "discharged" when the voltage drops to a certain level, well above zero. However, true 100% discharge can be considered to be when the voltage IS zero. If you keep on, after the zero volats point, forcing current thru the cell in the discharge direction (by means of an external voltage), the cell voltage will build up again, in reverse polarity. That is, instead of + at the +terminal, it goes negative. This is a "reverse charge". In some types of cell chemistry, any reverse charge will destroy the cell. It others it the cell remains chargeable in the correct direction, but its capacity will be reduced.

Over-charging: if you over-charge a battery, excess gas will be generated at each terminal. Rechargeable batteries incorporate recombination systems to re-absorb/re-cycle the gas under normal charging conditions. Overcharging is where the recombination system cannot cope with the excess gas. When the gas is not recombined, battery capacity is permanently reduced. So-called "sealed" rechargeable batteries have the electrode/plate dimensions and chemistry adjusted so that one electrode/plate gasses significantly first - this means that the recombination system only has to cope with one type of gas, which simplifies things and makes for better performance. If you reverse-charge it, the wrong size elecrode/plate generates the gas, so the recombination system cannot function as well. This means overcharging occurs far more readily in the reverse direction.

Ratbone58.170.162.104 (talk) 07:02, 5 July 2012 (UTC)

Thank you 2 for your help. Question resolved. However, any suggestion is always welcome. -- Livy (talk) 07:55, 5 July 2012 (UTC)

Independant existance of protons and neutrons in the nucleus

How correct?

The conventional conception of the nucleus of an atom pictures a group of protons and neutrons stuck together something like a cluster of grapes. (With the advanced proviso that due to quantum effects the nucleons don't have a precise location.) I'm wondering how accurate that picture is in reality. In the full QCD treatment, can you really separate things into four individual clusters of quarks, two each of uud and ddu? Or is it more like a sea of 12 quarks, six each of u and d? (Okay, quantum being what it is, I anticipate the answer to be "a little bit of both" - I'd appreciate what clarification you can give as to how things break down individual versus soup.) -- 71.35.99.136 (talk) 17:10, 4 July 2012 (UTC)

Yes, they are separate bunches. For example, if you collide energetic particles with a deuterium nucleus (i.e. one proton bound to one neutron) you can tell that the collisions are consistent with two bunches of three quarks each rather than a single mess of six quarks. Nucleons can be thought of as having a core of actual quarks and an outer shell of virtual pions. Binding between nucleons more or less occurs by overlapping their associated pion fields, so that the core quarks aren't directly overlapped. Dragons flight (talk) 17:59, 4 July 2012 (UTC)

Incidentally, if you want to know what a mess of quarks would look like without the bunches, then that basically describes a quark-gluon plasma, which can only form at very high energies. Dragons flight (talk) 18:02, 4 July 2012 (UTC)

Quantum field theory

Am I correctly interpreting this article? [7]

My interpretation is that a certain force is produced when a certain particle crosses its associated field. So for example a magnetic force is produced when an electron crosses the magnetic field. Is this correct? 176.250.196.132 (talk) 20:00, 4 July 2012 (UTC)

No, not really. What you're describing is basically a classical particle responding to a classical field. But quantum field theory is much more complicated than just being a matter of particles being subjected to a force when exposed to a field. For one thing, QFT is a probabilistic theory, instead of a deterministic one like a classical particle in a classical field. For another thing, in QFT, how many of each of the various types of particles involved there are in general changes during a QFT reaction. To understand QFT, you'll first need to understand quantum mechanics. Red Act (talk) 02:56, 5 July 2012 (UTC)

Higgs implications and hydrogen radii maximum (was: Hi! two completely unrelated questions)

1.If the Higgs boson is found (if it really is the Higgs boson, not a "Higggs-like particle" only) is there any experimental observation that can not be explained by the standard model? (and I'm not talking about the questions in scientific topics other than what physics is concerned about, like chemistry and biology, or even topics in physics like, I don't know, fluid dynamics, you know what I mean)

2.In an attempt to have fun with physics, I wanted to calculate that if we conducted a hypothetical experiment for checking where an electron is around a proton every nano second for 10^100 years (the biggest estimate I found for the lifetime of the universe) what is the farthest it will be found from the nucleus, given the probability distribution given by the 1s orbital's wave function. Now here's what I did, I calculated $\int _{r}^{\infty }\psi ^{2}\,dv={1 \over 10^{100}\times 31,557,600\times 10^{9}}$ where $\psi$ is the 1s orbital wave function in Hydrogen. well, wolphram alpha gives complex valued answers... what am I doing wrong?

thanks, the poster known as irrational number--2.177.20.5 (talk) 20:45, 4 July 2012 (UTC)

Your first question is answered in the second paragraph of the Standard Model article: "it does not incorporate the physics of dark energy nor of the full theory of gravitation as described by general relativity. The theory does not contain any viable dark matter particle that possesses all of the required properties deduced from observational cosmology." - emphasis added. --Tagishsimon (talk) 23:31, 4 July 2012 (UTC)

A Higgs at 125 GeV should be able to achieve dark energy with a simple scalar field parameter, but the Standard Model did not include such a particle until today. The light element big bang nucleosynthesis ratios will have to be recomputed. I expect them to be compatible with 100,000 solar mass black holes as dark matter,[8][9] primordial,[10][11] non-primordial,[12][13] or both.[14] 75.166.192.187 (talk) 00:59, 5 July 2012 (UTC)

In answer to number 2, I get 140 Bohr radii (about 7.4 nanometers) by doing the calculation you suggest. Perhaps you forgot to use a volume integral or something like that? Of course you can't really do that experiment, since any process for measuring the atom that extensively would change its behavior. Dragons flight (talk) 01:12, 5 July 2012 (UTC)

Regarding (2), please see Timeline of the far future. 75.166.192.187 (talk) 01:29, 5 July 2012 (UTC)

You probably need the integral of abs(psi)^2 157.193.175.207 (talk) 07:50, 5 July 2012 (UTC)

Mosquitoes

This may be a stupid question, but do mosquitoes only bite and take the blood from humans? I tried looking up the answer but it didn't show up. Plus, it seems a little odd that on a planet with millions of species, mosquitoes would only seek the blood of a singular species. Thanks, 64.229.5.242 (talk) 23:04, 4 July 2012 (UTC)

Per various sections of Mosquito, some of the beasties feed on vertebrates, including humans. But including all sorts of other animals. I don't know if any of the many types of mosquitoes specialise in humans; our article isn't very clear on that point. --Tagishsimon (talk) 23:17, 4 July 2012 (UTC)

There was a piece on a TV news show recently, possibly CBS Sunday, that discussed mosquitoes. Certain types of skeeters have "developed a taste for human blood", and of course those are the ones carrying various really-bad microbes. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:14, 5 July 2012 (UTC)

Mosquitoes are the most common big-bodied warm-blooded animals in many areas. Before that was Jurassic Park. μηδείς (talk) 01:29, 5 July 2012 (UTC)

By mosquitoes, I take it you mean humans ? StuRat (talk) 03:19, 5 July 2012 (UTC)

D'oh! μηδείς (talk) 03:39, 5 July 2012 (UTC)

I often confuse blood-sucking parasites, too. StuRat (talk) 01:00, 6 July 2012 (UTC)

Incidentally, there were also some 64-65 million years between dinosaurs and humans, and skeeters had plenty of food then too, I'm sure. StuRat (talk) 07:15, 6 July 2012 (UTC)

I have worked in remote areas, camping out, where I was the only human for 30km or more, and been bothered by mosquitoes. I've squashed them before they've had a chance to feast on me, and found them full of blood. I can only assume they had recently had a good feed on nearby wallabies (small kangaroos), rabbits, rats, etc, and think I might be a nice desert. Mosquitoes are quite an annoyance in many parts of Australia, but getting mosquito-borne disseases is very rare. This indicates that the same mosquitoes that feed on humans must be mostly feeding on wildlife whose significant viruses are not human-capable. (Ross River Virus, a nasty bug prevalent in the south-west, is one exception). Ratbone124.182.173.101 (talk) 01:37, 5 July 2012 (UTC)

Mosquitoes absolutely bite from a wide variety of animals, and each species has its own preferences. Most mosquitoes are willing to bend their preferences if their favorite food source is scarce, which is why we can raise many of them in the laboratory by feeding them mice. There are three reasons why a mosquito might prefer people: 1) It is an ecological niche filled with delicious protein. If an insect can efficiently fill that niche, it will, and it will be the best damn human-seeking blood sucker it can be; 2) Humans make it easy for species like Aedes egypti to breed in their own settlements by leaving water just sitting around for them to lay eggs in; 3) Some mosquitoes, to avoid their own predators, only hunt at night. Thanks to humanity's love of night-lighting, we tend to be the easiest prey at such times, especially on moonless, starless nights. In one study researchers captured nocturnal mosquitoes and analyzed the blood inside those who had recently fed. They found that, for these particular species, the suckers had a diverse palette on nights the moon was out. But on very dark nights, be it when the moon is unlit in the sky, or when it is concealed by clouds, the mosquitoes mostly fed on humans. And a secret fourth reason might be that we have no fur. If you ever watch a mosquito swarm feast on an unconscious mouse, they strongly prefer to bite bare skin, such as on the tail. Someguy1221 (talk) 01:47, 5 July 2012 (UTC)

Which are the best abatement products? There are some really good ones these days. 75.166.192.187 (talk) 02:48, 5 July 2012 (UTC)

As everyone has already said, yes mosquitoes most certainly do feed on other animals. Another example is Myxomatosis which is a disease that was introduced in Australia to try to control the introduced rabbit population. It spreads between rabbits by fleas and mosquitoes. Vespine (talk) 03:34, 5 July 2012 (UTC)

Note that the hybridization of mosquitoes can lead to new patterns of disease transmission, such as West Nile virus (see [15]). Many species are hybridizing presently as there are constant introductions, changes in range due to human modification of the land or global warming, and new environmental challenges for which hybrids have more genetic diversity to work with. As the old species gradually abandon their staid reserve and take on the greater adaptability of mixed genomes, we will discover that Nature has the power to get a whole lot meaner when provoked. Wnt (talk) 15:48, 5 July 2012 (UTC)

Glue and Plant Tissue

For an experimental project, I need an adhesive that can be in close proximity to growing plant roots without affecting the tissue. In other words, the glue should be biochemically "neutral" as far as the plant is concerned. The plant should grow the same way whether or not the glue is present.

The plant would not be placed in contact with the glue before the glue had set.

As far as the strength of glue needed, probably any of these would work. Silicone, epoxy, "crazy" glue, construction adhesive, or hot glue.

Can anyone tell me which if any of these will not affect the plant? Or suggest an alternative? Thanks, Wanderer57 (talk) 23:18, 4 July 2012 (UTC)

Silicone or, better, various types of wax will be non-irritating, but lack of air might be a problem. Can you not make the binding mechanically? I would look into grafting methods to find various binders that don't harm the plant.

Agreed. Toothpick splints and wire twist-ties? 75.166.192.187 (talk) 01:01, 5 July 2012 (UTC)

If you choose silicone, choose nuetral cure silicone sealant (used as fish-tank glue, roof-sealant, and other applications requiring compatibility with metal). Non nuetral-cure silicone slowly emits acetic acid for months after it has set, and the acetic acid might affect the plant. If the silicone is not specifically labelled as "nuetral-cure" and not specifically labelled for use in contact with metal, it is almost certainly the acetic acid kind. Ratbone124.182.173.101 (talk) 01:44, 5 July 2012 (UTC)

Funny, I had fishtank glue in mind. Didn't realize there was an acidic kind. μηδείς (talk) 03:37, 5 July 2012 (UTC)

Thank you all. Three very good answers in a few hours. Once again, the Wikipedia Reference Desk proves to be a brilliant resource. Wanderer57 (talk) 02:58, 5 July 2012 (UTC)

If you're still interested, the field ecologists I know use regular elmer's glue. One common use is to glue seeds to toothpicks for planting. The glue doesn't even interfere with germination. SemanticMantis (talk) 14:11, 5 July 2012 (UTC)

Thanks. I'm very much still interested. Wanderer57 (talk) 18:47, 5 July 2012 (UTC)

Elmer's glue is water-soluble. Won't the roots get wet, then dissolve the glue ? StuRat (talk) 00:58, 6 July 2012 (UTC)

I probably should have mentioned this. The experiments require a humid environment. The purpose of the glue is to attach components together in a particular configuration. This will create a space in which roots can grow. The plant roots and stems will not themselves be glued to anything.

Based on the above inputs, I'll begin experimenting using neutral cure silicone and grafting wax. Wanderer57 (talk) 22:20, 6 July 2012 (UTC)

July 5

Why do humans seem to prefer drinks at extremes of temperature?

It occurs to me that humans on average appear to prefer either hot or cold drinks but not tepid drinks. Are there any theories on why this is the case?--108.46.98.134 (talk) 01:23, 5 July 2012 (UTC)

Warm drinks (foods in general) convey taste and odor better. I like cold drinks because they are...cooling. Agree with the question's premise, but can't think of any obvious articles. μηδείς (talk) 01:26, 5 July 2012 (UTC)

Ambient temperature is associated with stagnation and microbial contamination. It's one of the preferences which separates the amphibians and below from the reptiles and above. 75.166.192.187 (talk) 01:32, 5 July 2012 (UTC)

Interesting and somewhat plausible theory, but I can't see there being a natural preference for cold drinks in areas where humans originated. Unless maybe mountain streams? Got a source? μηδείς (talk) 01:37, 5 July 2012 (UTC)

Since most drinks are served either hot or cold, tepid would be associated with something that's been left out. I wonder if this is actually an evolved preference, or if it's just something we learn by growing up in such a society. A culinary meme, if you will. Someguy1221 (talk) 01:50, 5 July 2012 (UTC)

That's the real question right there. The benefits of cold water to the parched are so obvious that it's not surprising there are psycho-physiological mechanisms that make it desireable. And that's the thing to keep in mind here - we generally like hot or cold drinks in specific context; that is, we tend towards cool drinks when it is hot and hot drinks when it is cool, so clearly this is in part a body temperature regulation and hydration issue, which of course is entirely intuitive; we all know that and the mechanisms are known to some degree. As to the theory that tepid liquids are avoided due to their propensity to contain live parasites in relatively large numbers, that's sounds petty reasonable to me and in fact has always been the assumption I think, though of course, like many phenomena examined by evolutionary psychology of that sort, it's relatively hard to come up with firm empirical validation. But as you say, the real question is, how innate are these preferences and how much are they influenced by experience and culture? Giving my own (very hasty and very impressionistic) opinion, I'd hazard that most cultures show a preference to stay away from the middle ground where possible, and show a preference for colder or warmer drinks and that these preferences are lop-sided in such a way that persons from very cold or very warm climates will be more likely to prefer hot or cool drinks respectively more often while tepid water is probably also common amongst persons in particularly cold climates where truly cold water is not advisable. At the same time I would anticipate that people in temperate climates probably do not show as much variation on the whole. Context is everything, is basically my argument. All highly speculative, of course. It's not for nothing that a fierce trans-atlantic debate presides of the warm vs. cold beer issue, after all! And there's doubtless to be considerable individual variation owing both to psychological metabolic factors. Snow (talk) 03:51, 5 July 2012 (UTC)

I agree - I think it is cultural. When I was 6 years old, I was diagnosed with a medical condition that meant I was alergic to caffiene. So I never got used to drinking tea and coffee. I pretty much only drink water, which doesn't need to be heated. In summer I like my water refigerated, but at other times I don't care if it is tap-cool or even a bit warm. But I never ever want it hot. My friends sometimes say they cannot understand why I don't want a hot drink - I on the other hand cannot realy understand why they do want it. Cyclists and hikers get used to tepid water. Guess it's just what you are used to. Wickwack120.145.4.60 (talk) 01:56, 5 July 2012 (UTC)

It might be but the preference seem so ubiquitous and unvaried that I think it has to be more nature than nurture (even if it's a mix of the two). There are drinks that many people like that they think are repulsive at room temperature. For example many people love soda but thinks it's awful at room temperature. Adding to this might be the fact that coldness increases sensitivity to sweetness so a room temperature soda may be found cloying, but I think it's beyond that (especially when you consider that beer is the same way for many, though it's savory). I like the microbial theory but I wonder if the evolutionary time since we've had the ability and resources to choose hot or cold over unregulated temperature is long enough to have made this evolution driven (by this I mean selected for, rather than something somatically innate).--108.46.98.134 (talk) 01:59, 5 July 2012 (UTC)

Ah, I've just thought of something. Live prey (and it's blood) is hotter than the surrounding environment, and running streams, maybe from mountain meltoff, is colder than the surrounding environment. You see where I'm going with that? It would be interesting to make a study of other animal preferences.--108.46.98.134 (talk) 02:06, 5 July 2012 (UTC)

Significance is imparted to rituals by expending effort thus socially preferred norms would tend to be dictated by those preparation procedures that result in occasions that seem to have greater significance, thus when people get together to share in the act of imbibing a beverage it is likely to be a cold or hot beverage as those temperatures imply that effort was expended to arrive at those temperatures. Bus stop (talk) 02:17, 5 July 2012 (UTC)

As this is the Science Desk, I would really like to see some science in the answers. As it happens, I don't agree that humans, in general, like beverages at the extremes, and, to the extent that we appear to do is relatively modern preference. However, my opinion is not very useful. Bielle (talk) 02:23, 5 July 2012 (UTC)

On the contrary, your opinion is appreciated. It takes courage to ask the right questions, among other things.

Please see PMID 22710391. 75.166.192.187 (talk) 02:36, 5 July 2012 (UTC)

Ingeresting but one of the studies linked in the sidebar of that page came to the opposite conclusion [16]. Rmhermen (talk) 03:01, 5 July 2012 (UTC)

I believe both of them. 75.166.192.187 (talk) 03:14, 5 July 2012 (UTC)

One of those studies is looking at fluid consumption during exercise and the other at heat-exposed workers. I don't think the results can be generalized to the general population. A8875 (talk) 03:49, 5 July 2012 (UTC)

Indeed, general oral sensation is pertinent here. 75.166.192.187 (talk) 04:04, 5 July 2012 (UTC)

The preference for cold soda and beer mystifies me, because these things are more flavorful at ambient temperature, or at least, warmer temperatures than the almost-frozen American ideal. Looking at [17], the blame might go to poor quality of some of the old mass-market American beers, which are better not tasted on one's way to the vomitorium. But best not drunk to begin with... ;) Wnt (talk) 04:28, 5 July 2012 (UTC)

As a yank living in Poland, I couldn't disagree with you more. One of the things I really, really miss here is ice-cold drinks. Refrigerators for beverages in stores here are often not even switched on. Forget about getting a big fat pitcher of ice water when you sit down in a restaurant. Ice seems to be a precious commodity, and you can't just stroll over to the nearest gas station and pick up twenty pounds of ice when you have a party at your house. Even when I ask for LOTS of ice in a restaurant I usually end up with a couple of pathetic looking mini-cubes. Even ice cream is served a lot warmer than it is in the states. Looking on the bright side, I haven't had an Ice-cream headache in ten years. Another thing I really, really miss is window screening. Not like there's a shortage of mosquitoes here. Dominus Vobisdu (talk) 06:15, 5 July 2012 (UTC)

This is definitely part climate and part culture driven. Poland is a cold country, parts of the USA are warm. In England, a cold country, they drink warm beer. In Australia, a hot country, we drink ice-cold beer. And, yes, if you try Australian beer when it's warm, it tastes like vomit. Doesn't matter when it's drunk ice cold. Wickwack121.215.20.217 (talk) 06:32, 5 July 2012 (UTC)

cough cough cough When you drink "Australian domestic standard lagers" at anything above 3-5°C they taste sub-optimal. Other Australian beers, such as browns, blacks, porters, stouts, or generally ales taste quite lovely above 5°C if the drinker has actually been taught about beer. Fifelfoo (talk) 06:46, 5 July 2012 (UTC)

English ales are most definitely not served warm. If a pub serves you a room temperature pint, go somewhere else, because they don't know what they're doing. Ales should be served at cellar temperature, which is 12-14C. Fgf10 (talk) 09:34, 5 July 2012 (UTC)

I'd also dispute England being called "a cold country". --Dweller (talk) 10:53, 5 July 2012 (UTC)

And so does Wikipedia. --Dweller (talk) 10:55, 5 July 2012 (UTC)

The WP article gives the summer maximum in England as 21 C. That's about our winter maximum in most Australian cities. The lowest recorded temperature in England was -21.5 C. The lowest recorded temperature in Perth Australia was about -1 C. It routinely snows in England. We never get snow in Australia, except in high mountains. Yep - England is cold. Australia is a hot country. We know that - when British made cars were still available, Australian heat rapidly ruined upholstery and paintwork. However, beer at "cellar temperature", 12 to 14 C, would definitely be regarded as "warm" by Australians. We refigerate our beer. Wickwack60.231.243.191 (talk) 11:38, 5 July 2012 (UTC)

You should read more carefully. The section begins "England has a temperate maritime climate: it is mild..." It then cites our summer maximum as "not much higher than 32 °C", a whole 10 degrees higher than what you thought you'd read. Australia may indeed be hotter than England, but that does not mean England is "a cold country". Your argument is like saying that Scotland is a hot country because Greenland is colder. Cold countries do exist, but not in this bit of the Atlantic. --Dweller (talk) 11:54, 5 July 2012 (UTC)

Perhaps you should read more carefully, Dweller. Maybe think a bit more clearer too. I compared like with like. The WP article in the climate table gives the mean summer maximum for England as 21 C, as I said. Go look. Naturally, England will get days where this is exceeded, and in fact the same section of the same article gives the recorded maximum of 38.5 C, not 32 C. But England won't get 38.5 C at all very often. In the same way, our (Perth) mean summer maximum is 31.5 and the max recorded is 47 C, but we see ~42 C every summer. Most people in the world would regard England as cold. Comfort-wise, and thirst-wise, which are the only things relavent to the OP's question, there is a big difference between a 21 C summer and a 31 C summer. And Australia has other areas with a summer mean around 40 C. Your statement about Scotland and Greenland is meaningless in this context. The reality is that England is cold, and Greenland is extra cold - so cold that not many folk live there (the entire country has a population less than an average town). Wickwack120.145.144.189 (talk) 15:49, 5 July 2012 (UTC)

It was 22C here in the southeast of England today (phew, what a scorcher!). It might get over 30C once or twice in a summer, although it hasn't yet this year. However, we have much milder winters than our European nieghbours, so it aint all bad (sorry about your car Wickwack). Back to the subject - I agree with Fgf10 about "cellar temperature" beer, however I am quite happy to drink beer from cans and bottles at room temperature, although many youngsters prefer theirs chilled - there's no accounting for taste. But how did you foreign and Commonwealth chaps get cold beer before refridgeration? Alansplodge (talk) 22:10, 5 July 2012 (UTC)

You must be joking cause, ~20-22C is room temperature, as is, what humans make their environments on purpose when they have climate control. And Scotland Julys and Augusts wow, those are like Aprils and Octobers here, you might want to hold onto a beautiful Scottish woman just to keep from dying of hypothermia (or, you know, like put on a sweater or something). Sagittarian Milky Way (talk) 23:39, 5 July 2012 (UTC) Sagittarian Milky Way (talk) 23:39, 5 July 2012 (UTC)

Many methods existed, including chilling beer in a cold stream or root cellar, or using evaporative cooling in dry climates. Ice was also collected in winter and stored in a large, insulated warehouse, so it would last through summer. Then, industrial scale refrigeration became practical long before home refrigeration, leading to daily ice deliveries to keep iceboxes cool. StuRat (talk) 22:19, 5 July 2012 (UTC)

I know somebody called for more science above, but let me offer you few other theories based purely on personal expierience. First - drinks with carbon dioxide do taste better cold, but at certain temperature, not just generic "cold". This I learned from personal expierience with both sparkling wine (and there seems to be whole art regarding how cold it should be served) and Coca-cola. And for that reason I doubt it is just a cultural thing - that would require believing in the stereotipe and though I had heard before that these drinks taste better chilled, I never really believed it and as a matter of fact hated cold coke up to last summer, when I bought it near ice cold and found it to be way better than I'd ever had expected. Secondy tepid may taste better, because taste buds get sort of temperature shock, when it's too hot or cold. This also from expierience - I have trouble tasting how much sugar is in tea when it is very hot. And thirdly - tepid means close to body temperature, so perhaps this can confuse sense of taste too. At very least it confuses the sense of touch to point you can berely feel the fluid touching you, be it in drink or anything else. This might confuse your brain, because you may know you are drinking, but you don't fully feel it. ~~Xil (talk) 00:05, 6 July 2012 (UTC)

I'm confused what you mean by 'that would require believing in the stereotipe'. As with many things which may be at least partially cultural like the associated of pink with feminity, all it requires is people to have learnt or adapted to that association in some way which isn't surprising if it's widespread practice. The fact that one (or a small number of people) did not believe it but later found they agreed is pretty much useless. For starters, thy may still have been sufficiently exposed to the phenomenon that even if they try to disbelieve it. And for example as to your specific experience, 'coke up to last summer' suggests the circumstances could easily have affected preference. I don't think anyone has disputed people may find cold drinks better in specific circumstances like when they've been exposed to heat for a while and are perhaps even somewhat dehydrated. See for example A8875's comments. Nil Einne (talk) 07:48, 6 July 2012 (UTC)

Yeah, and that association you make is stereotype. You hear that this or that is better hot/cold and you start to believe in it - it tastes better, because you expect it to. My whole point was that I didn't have any ilusions of cold coke being tasty, matter of fact I didn't like it cold. Therefore I find that me finding it tasty cannot be explained with it being cultural thing (and probably other people will also find that they don't always find things tasty according to what society tells them, but based on their own expierience). Yeah, it was summer and obviously it could have had some effect, but since then I've been trying to select cooler coke, whith varying success and in different seasons too. Also same thing wih champagne, which I don't drink for being thirsty - nobody here really cares, if it is cooled, I technicaly knew it is recomended to cool it, but didn't think it makes much difference, untill, purely by accident, I happaned to taste it cooled. For sure climate and perhaps some traditions can explain preference in some cases, but not always - the food temperature does affect its taste. I figure it has more to do with body temperature and drink temperature being relative to it, than with culture ~~Xil (talk) 08:42, 6 July 2012 (UTC)

evidence for evolution, as opposed to adaptation.

I've been looking at the Evolution article on Wikipedia. It discusses adaptation (the process whereby an organism becomes better suited to its environment-e.g. the snake loosing its legs, whales gaining flippers, and even elephants growing trunks.) as a result of natural selection, but not evolution (the process whereby an organism grows in complexity-e.g. single celled organisms becoming multi-cellular). So what evidence is there for evolution, and how does this fit into the idea of natural selection?

I'm asking this from a genuine scientific perspective not as a naysayer, and i'm looking for answers, so creationist bashing will be pointless and annoying. — Preceding unsigned comment added by 86.176.99.114 (talk) 12:39, 5 July 2012 (UTC)

For what it's worth my understanding of evolution includes both processes you mention. Simple organisms may become more complex if it affords them some advantage in survival or already complex organisms may undergo alterations in their make up if these alterations afford them some advantage in changing circumstances or using the present circumstances in a more efficient way. Evolution is (usually) a slow process, the changes may take place over thousands of years which effectively make them invisible to human beings (were it not for fossils). — Preceding unsigned comment added by 86.4.184.18 (talk) 12:56, 5 July 2012 (UTC)

yes but surely single celled organisms are the ultimate replicating machines, so why would a gene ever be passed on to the next generation if it encourages multicellular organisms.

While it's true that the life cycle of single celled organisms is typically significantly faster than those which are multicellular, this does not necessarily equate to the best survival/reproduction strategy. Most adaptations do come with a price (a species may develop a new organ that is incredibly useful in a new environment but require additional sustenance to support it or a species that previously benefited from having large numbers of offspring, any which of might propagate its genes, could adapt to have fewer young that it devotes more resources towards on an individual basis. In each case, its immaterial to the gene which strategy leads to its replication, so long as said continuation occurs, and for each organism there are multiple genes that all operate under "selfish" principles but which are bound by a mostly common fate (aside from the random mutations which drive evolution and the re-combinatorial aspect of sexual reproduction). Life evolved from single-celled organisms because some of the afore-mentioned random mutations led to new (multicellular) forms whose complexity allowed them to out-compete their unicellular counterparts. Sure, a bacteria may be able to reproduce thousands to millions of times within the lifecycle of certain "higher" organisms, but those more complex organisms will likely get to reproduce more times. At the end of the day, the gene that survives for 1000 generations that are a day long each (say a gene in a mayfly) has been exactly as "successful" as a gene that survived for one generation of a thousand years in a redwood tree, though they may have very different long-term chances moving forward. I think the missing piece of the equation you might be looking for is chance. Mutations occur constantly in living organisms and are simply the result of the basic bio-physical properties of the matter that they are constructed of. Virtually all mutations are non-conductive to the organism's chances of surviving, but rarely a mutation leads to a change in the organism that, just by chance and no more elementary principle, happens to up the organism's odds of surviving long enough to pass on its genes. And even amongst this subset of lucky benefactors, most will not survive, because they are still in a wide and uncertain world of competing organisms. But over enough time, these beneficial traits begin to accrue just through probability and the result is increasingly complex organisms that are descendents of those happy few who just happened to have the right adaptations in the right place at the right time. Snow (talk) 16:23, 5 July 2012 (UTC)

The idea that evolution somehow favours complexity is false ; [[18]] is a "primitive" organism which descended from "more advanced"/"more complex" canines. 157.193.175.207 (talk) 12:58, 5 July 2012 (UTC)  : The idea that evolution somehow favours complexity is false ; [[19]] is a "primitive" organism which descended from "more advanced"/"more complex" canines. 157.193.175.207 (talk) 12:58, 5 July 2012 (UTC)

− − ::my point exactly. so why do complex organisms exist?

While it's by no means a complete answer to your question, I suspect that you'll find our article on dictyostelium discoideum of interest. It is a slime mold that sits squarely on the border between uni- and multicellularity. TenOfAllTrades(talk) 13:16, 5 July 2012 (UTC)

86.176.99.114—"Natural selection" is the mechanism of "evolution". Natural selection is terminology for survival and reproduction. That organism which fails to survive and reproduce also fails to pass on traits to a next generation. Success at passing on traits (encoded in genes) drives evolution. There are other factors, but I am just addressing one of the basic ideas involving evolution. Bus stop (talk) 14:00, 5 July 2012 (UTC)

Yep. There is no built-in evolution to greater complexity in the sense that the Original Poster used. That's not what is meant by "evolution" when biologists use the word. What has happened is that a mutation of single-celled organisms gave then the ability to do well in some niche environment when a number of them are clumped together; then another mutation gave some level of specialisation which better suited some other niche environment. And so on... The result after a vast number of years and much change in environment is a distribution of organisms over a range of complexity, and the number of organisms of any complexity is roughly inversely proportional to complexity. This is clearly illustrated by considering a human. One (1) healthy human has in his body about 10 times the number of micro-organisms than human cells. Wickwack120.145.144.189 (talk) 15:25, 5 July 2012 (UTC)

Genetically speaking, multicellular organisms aren't really more complex than related single celled organisms. Notably, consider amoeba, e.g. Polychaos dubium, which our article says contains 670 billion bp as opposed to just 2.9 for the human genome. Single cells can have "eyes" (see Dinoflagellate), "legs" (i.e. pseudopods), "kidneys" (i.e. contractile vacuole), and can engage in some fairly impressive behavioral feats (e.g. Mycetozoa solving a maze, if they count, or the fast and purposeful swimming of the Paramecium). Now what is true is that there is a general power law about viscosity and drag - if you want to move fast, make great migrations from pole to pole, or even up and down the tidal zone, you need a big body; and for a big body to work you need some kind of increased internal surface area for cells to respire and acquire nutrients, which is pretty close to an order for multicellularity. (Though true, as our skeletal muscles do, the outside environment could be brought to the inside of a larger syncytium through tubules; if that can scale up to a whole organism though, nobody's done it) Now because there are ecological niches that require varying degrees of fast mobility, and because fast mobility virtually decrees multicellularity, it is inevitable that evolution will come up with big organisms eventually that can fill those niches, because the ones that get started on the task will prosper. Wnt (talk) 15:41, 5 July 2012 (UTC)

First let me clarify some terminology - it might help the articles make more sense. "Evolution" just refers to any and all change in a group of organisms over time. This can mean any change including random characters getting fixed by chance through genetic drift. (See the Evolution#Mechanisms section for other ways of evolution taking place.) Natural selection is just one way in which evolution occurs. Evolution by natural selection may lead to an organism being better suited to its environment (e.g. fur color in mice that move to a desert becoming lighter) or it may not (e.g. spread of ultraselfish DNA. see Intragenomic conflict).

Other than the terminolgy, I see two questions here - Why does complexity (multicellularity) evolve? and What evidence/examples do we have for it?

For the first question, the usual reason for an organism to get more complex (unicellular to multicellular, complex tissues and organs, complex nervous systems etc.) is to be able to better deal with other organisms. These reasons include avoiding predators (bacteria and algae form biofilms, many algae are colonial), becoming more efficient predators or beating competition - in land plants erect stems will hog all the sunlight and kill off simple green goo on the mud, a multicellular fungus can put resources gathered from a large area into growth, bigger animals can move faster etc. Much complexity comes to solve problems created by other complex innovations. A bigger body with more muscles helps you avoid prey, but now a nervous system will go a long way in making it coordinated. However, depending on the exact selective pressures and the chance factors involved, evolution can progress towards simplification (lean and efficient) or complexity (eat/roll over everyone else with impunity)

For the second question about evidence/examples the most common evidence is to construct a phylogenetic tree based on DNA and other characters. In the most likely tree it, we look for all the points where a group of organisms all inherited a complex trait from a common ancestor. For example, this way we can find several cyanobacteria that are multicellular but have close unicellular relatives. See the article on multicellular organisms. also have a look at [20] for an idea of how it's done.

Hope this has been helpful Staticd (talk) 18:01, 5 July 2012 (UTC)

ok thanks, i get what you're saying. can this process be empirically proved? — Preceding unsigned comment added by 86.176.99.114 (talk) 20:15, 5 July 2012 (UTC)

Well, Chlorella vulgaris repeatedly evolves a colonial habit to evade predation in the lab. But I doubt it's known that it's never colonial in the wild, or in its history... still I tend to think that it evolves pretty easily; the question is only whether the environment is pushing the organism to do so. See [21] for a nice paper. Wnt (talk) 00:49, 6 July 2012 (UTC)

Can Evolution be proved empirically? The short answer is 'Yes'. The long answer depends on your definitions. Evolution is both a fact and a theory (see Evolution as a fact and theory). The fact of evolution is the observation that evolution occurs. We've seen it happen in the lab, and in the wild. We came up with the Theory of Evolution to explain the fact of evolution. It has since become one of the most well supported theories in all of science. See Evidence for evolution; there's a lot of it, from a number of different disciplines. We use evolution to create medicine, create new "kinds" of animals, develop technology, understand biology, and so forth. It's a cornerstone of biology nowadays, and that's because it's been demonstrated to work. In a colloquial sense, I think that applies as empirical proof. However, you must understand that science doesn't work in "proofs"; nothing in science is ever "proved", ever. The theory of gravity isn't proved, or germ theory, or any other. When a hypothesis becomes well tested and accepted within the scientific community as true (to the best of our current ability to understand it), it graduates to become a theory. That's the "highest rank" in science, and if anything qualifies for it, it's the theory of evolution. Take a look at the articles I linked to above, including Objections to evolution; hopefully they'll clear things up better than I can.   — Jess· Δ♥ 03:48, 6 July 2012 (UTC)

Heat Transfer

Im assuming that the equation Q=hA(dT) is needed to find the heat transfer rate through an igloo given that it's diameter is 3m, the temperature inside the igloo is 5C and the temperature outside is -20C, the heat transfer coefficient between air and ice is 10W/m^2K and the thermal conductivity of ice is 0.5W/mK. I would use a=pid^2/2 to find the area of the igloo as the diameter is given. This gives me a value of 3534.29J/S. However given all this info, is it possible to find the temperature inside the igloo at which the ice would start to melt? I can't see how you can do this without the heat transfer coefficient between ice and air but I'm not sure how to obtain this from the data available. 176.27.210.194 (talk) 13:28, 5 July 2012 (UTC)

To find the internal air temperature required to begin melting the ice, you only need the air-to-ice transfer coeficient (you gave that as 10W/m².K) and the heat (in watts) flowing thru the ice. You can't calculate the heat flow thru the ice though, becuase although you have the thermal conductivity of the ice, the temperature difference of the ice and the outside ice-air interface (10W/m².K again) in series (it's 0 C on the inside and -20 C on the outside) but not the ice thickness. You need the ice thickness. Ratbone121.221.80.11 (talk) 15:14, 5 July 2012 (UTC)

the ice thickness is 0.1m but I still don't see how you can calculate the internal air temp required to begin melting the ice without the heat transfer coefficient between ice and air. I came up with the equation Q=A dT/(1/hi+t/k+1/ha) where hi is the heat transfer coefficient between ice and air and ha is the heat transfer coefficient between air and ice? 176.27.210.194 (talk) 15:36, 5 July 2012 (UTC)

Just consider how you would derive that equation. Take the temperature inside to be T1, the temperature at the incide air-ice boundary to be T2, the temperature of the outside ice air boundary to be T3 and the ambient outside temperature to be T4. You then assume steady state, so

hi (T1-T2) = k/t (T2-T3) = ha (T4-T3). You then have 2 equations allowing you to eliminate the two intermediary temepratures T2 and T3, so that you can write Q in terms of T1 and T4 only, yielding the eqation you give. But now you are interested in T2, because if this becomes larger than 0°C the ice will melt. Count Iblis (talk) 16:03, 5 July 2012 (UTC)

[Edit conflict]You gave in your original post the heat transfer coefficient between ice and air as 10W/m².K. It works the same in both directions. You have the ice thickness (0.1 m) and the ice thermal conductivity (0.5W/m.K). Use the geometric mean of inside area and outside area. So you can calculate the ice thermal resistance R_ice. You have the iglos outside diameter (3 + 2x0.1 m), so you can calculate the igloo outside area. With the igloo outsid area and the ice-air transfer coeficient (10W/m².K) you can calculate the outside ice-air notional thermal resistance, R_ice-air. The total thermal resistance, inside ice surface to outside ambient is the sum of these two resistances. So now you have a resistance with a ΔT of 20 K (inside surface just melting so its 0 C, outside ambient is -20 C). So you can now calculate the heat flow, Q = ΔT/(R_ice+R_ice-air). And, now that you have the heat flow, you can, with the inside air-ice inteface, calculate the required inside air temperature. Ratbone58.170.169.167 (talk) 16:39, 5 July 2012 (UTC)

2012 summer weather

Why is the summer weather this year cooler than the average temperature from the last few years everywhere in the northern hemisphere? Clover345 (talk) 15:15, 5 July 2012 (UTC)

Not everywhere (just ask the people in the US who don't have power right now how they are doing without AC). In North Western Europe we've had rainy and cooler weather because the Jet Stream is not as far North as it should be. Count Iblis (talk) 15:55, 5 July 2012 (UTC)

has this affected Southern Europe? Clover345 (talk) 16:03, 5 July 2012 (UTC)

They have had hot weather there, temperatures have been above 40°C in Spain. But this has affected parts of Southern Europe, it has caused more rain in some places. Count Iblis (talk) 16:25, 5 July 2012 (UTC)

The OP's question has false assumptions. Throughout the Northern Hemisphere there were areas with record or near-record warmth in the past month. Seoul, South Korea and Denver, Colorado (US) had their hottest June on record, while Malta had its second-warmest June on record. In Puerto Rico, June 2012 was the hottest of any month on record. And I found these just with a quick google search.

I assume the OP is from the UK, where temperatures have recently been below normal. That's the way that weather works, record high temperatures in one area often mean that other areas at the same latitude will be below normal, and vice versa. That's because temperatures are roughly zero-sum; the principal cause of abnormal temperatures is abnormally amplified Rossby waves, which send cold, arctic air much further south than it normally would be, and conversely sends warm, tropical air much further north than it normally would be. This image illustrates it quite nicely.-RunningOnBrains^(talk) 18:01, 5 July 2012 (UTC)

We've broken many records for hi tempos here in Detroit, too, including 101°F just yesterday, which was a record for July 4th. StuRat (talk) 00:42, 6 July 2012 (UTC)

were entering a ice age — Preceding unsigned comment added by 74.74.255.141 (talk) 03:11, 6 July 2012 (UTC)

Anal flu

I tried to look this one up a while back, but never came on a satisfactory answer. Suppose a person is somehow exposed with influenza solely by anus, e.g. by contaminated toilet paper at a public restroom. What will the course of the infection be like?

• Will the flu quickly travel through the bloodstream to the lungs and cause a normal infection?
• Will it cause a milder infection because the immune system gets a crack at the virus before it gets a crack at the lungs?
• Will it cause weird, bizarre symptoms, your rectal lining falling out in strips or something?

In the most optimistic view, I'm thinking it might be a way to evade Captain Trips...

Wnt (talk) 16:03, 5 July 2012 (UTC)

Diseases do differ in effects according to how they are transmitted, with respiratory anthrax, for example, being much deadlier than the other kinds. There is what's called the stomach flu, although it usually isn't even from the flu virus, and it enters orally. What in the world that you would be doing with toilet paper that it got in your colon I cannot imagine. The Infection would likely be largely limited to the lower intestine, since there isn't significant backwards flow, and the flu virus mostly just infects epithelial cells of the mucosal tissue, with the ache and fever causing chemicals travelling in the blood being part of the immune response, not viruses or infected blood. So yes, it might work as a sort of suppository inoculation. μηδείς (talk) 16:18, 5 July 2012 (UTC)

Flu virus have evolved so they are optimised to multiply in the uppr respiratory tract. So, for a typical flu, the ansers to your questions in order are, No, Yes - very much so, assuming the immune system even notices it, and No. However, flu viruses can range from hardly infective to absolutely rampant. So, for the purpose of the Captain Trips story, yes , a realy bad bug could get going via someone's fundametal orrifice. But plenty of humans don't even wash their hands, let alone wash in a way that prevents bug transfer. Have you seen how nurses in a hospital wash their hands? They turn on and turn off the taps with their elbows - this is the only way to prevent hand-tap-hand transmission of bugs. Plenty of humans pick their nose etc right after wiping anyway. In many countries there is no facility to wash. So your question is almost certainly not relavent. Wickwack58.164.237.212 (talk) 16:20, 5 July 2012 (UTC)

Most pathogens have a fairly restrictive epidemiology, meaning they have a very specific gambit in how they reproduce, including highly refined mechanisms to get into and out of the various tissues they need to exploit for their life cycle. Some are less picky than others, of course, and some are happy opportunists who are streamlined to infect you in one way but are capable of taking advantage of uncommon circumstances to propagate. You have perhaps heard the story going around in the popular press right now of a young American woman who recently lost multiple limbs to flesh-eating bacteria after she gashed her leg open in a swimming incident. The bacteria in question was not some rare species from deep in the Congo but rather a commonplace strain of Strep B, the stuff that usually gives you a sore throat at worse. It was just a case of the bacteria getting the drop on an immune system that was unable to adapt in time to keep the bacteria from replicating far beyond what it would usually be capable of inside a host. One famous example of a very opportunistic Yersinia pestis -- you probably know him from his more common and charming monicker the Black Plague. Those infected with plague will manifest symptoms in one or more of three clinical categories defined by the systems hit hardest by the bacteria - bubonic plague (infected lymphnodes), pneumonic plague (infected lungs), and Septicemic plague (infected blood). Blood infections are almost always one of the worst case scenario's for a given pathogen, since a blood infection means that A) the immune system is already doing a bad job of containing the pathogen since it does a lot of its work through the blood and B) the pathogen now has a free ride to virtually any organ/tissue where it might flourish. Note though that it may not be in the pathogen's best interest to spread too fast, since it may be a type that tends to preserve its host as long as possible so that it can spread to still new hosts. All of that said, viruses are typically more "picky" than bacteria - they usually follow a much more predictable approach, though they can also be much more virulent -- in terms of just how resistant they can be to the immune system and the severity of the symptoms they cause -- once they are established. Snow (talk) 17:06, 5 July 2012 (UTC)

Higgs field

Why isn't the Higgs field a preferred reference frame, in violation of relativity? --108.225.117.142 (talk) 17:13, 5 July 2012 (UTC)

Because it is a scalar. Then, despite it having a nonzero vacuum expectation value, the vacuum is still Lorentz invariant. And it wouldn't violate special relativity for a vector field to get a nonzero vacuum expectation value and thereby to spontaneously break Lorentz symmetry. Count Iblis (talk) 17:22, 5 July 2012 (UTC)

But isn't the point of relativity that you can't say for sure that Frame A is stationary and Frame B is moving, because B could be stationary with A moving in the opposite direction? But can't you be certain that the Higgs field is stationary and anything that moves relative to it is actually moving? --108.225.117.142 (talk) 17:35, 5 July 2012 (UTC)

Note that scalar fields include gravitational and electrostatic potential. The point is, a particle with a +1 charge has a +1 charge no matter how fast it is going relative to you, and I assume the same applies here. (Not that I understand the Higgs mechanism really!) Wnt (talk) 19:01, 5 July 2012 (UTC)

The vacuum (with the Higgs field) looks just the same to both observers. Count Iblis (talk) 02:33, 6 July 2012 (UTC)

Waste heat differential recycling in air conditioning

Given that window mounted ACs try to have the condensate run over to the condenser to help cool it by evaporating, thereby recouping the energy expended to condense the warer vapor, I notice that central ACs don't seem to do that; they pipe the condensate outside and just dump it. However, they pipe it all the way out next to the external housing, and dump it there. Why don't they just spring for the additional foot of tubing and let the condensate pour onto the condenser coils? The waste in energy must be significant. Gzuckier (talk) 20:06, 5 July 2012 (UTC)

Many do, but the use of maximum efficiency designs is hampered by their complexity, sometimes. In many cases waste heat recycling upgrades can be much more efficient, but if the body was designed and painted with air/liquid surface use assumptions, which is very likely, then waste heat energy differential use improvements can be major upgrades. Often, replacement of the primary components can cause increased efficiencies, too. Infrastructure upgrades are well worth the investment. 75.166.192.187 (talk) 20:51, 5 July 2012 (UTC)

I've noticed some of the problems that my window A/C has, due to this efficiency improvement:

1) Rather than draining the condensate, they pool it for reuse, which allows microbes to grow in the condensate. Mine blows out mold spores after I first turn it on. I'd gladly accept lower efficiency if I could prevent this.

2) The way the fan dips into the pooled water to splash it on the cooling fins makes a horrible noise, rather than the smooth, continuous sound it would make otherwise.

3) I wonder if the added load on the fan shortens it's life.

So, like with any efficiency improvement, there are trade-offs. Apparently the makers of window units think their customers are more willing to put up with the inconvenience to save money than those with whole house A/C. StuRat (talk) 00:50, 6 July 2012 (UTC)

What you have are the symptoms of a blocked condensate drain, and it is a health hazard. Sometimes insects crawl in and block it, particularly if the aircon is not used for a few days. Or the aircon may have been incorrectly installed - some have 2 optional ports on the condensate tray for drain hoses, which mean the aircon comes from the factory with both ports blocked, and installers forget to install a drain hose. Indeed, the vibration caused by fan blades hitting water will not be good for it. Note that in a window mounted "unit aircon", the evaporator and the condenser are at the same height, so to run condensate (which comes from the evap) over the condenser, you'd need a pump. Ratbone120.145.45.13 (talk) 03:02, 6 July 2012 (UTC)

And, to avoid the expense of a pump, they just let the fan hit the pool of condensate water, which splashes some of it on to the cooling fins, and call that "good enough". StuRat (talk) 07:11, 6 July 2012 (UTC)

You're not listening, Stu. It's not normal for the fan to touch water. It's not good for it. It's not meant to. If yours does that, it's faulty. Ratbone121.221.79.93 (talk) 08:03, 6 July 2012 (UTC)

It's not a bug, it's a feature. There are fans which splash in a pool of condensate: it's called a "slinger ring", that surrounds the fan and directs water into the coils. I think in part it's intended to evaporate as much condensate as possible to avoid excessive drippage on people and things below, with the added benefit of improving efficiency. Piped condensate usually drains by gravity, nearly always to a place that's convenient for discreet drainage and not suitable for use to augment the condenser. Acroterion (talk) 21:46, 6 July 2012 (UTC)

Ratbone, haven't you ever noticed that a window A/C unit makes a horrible sound like a dead squirrel grinding between gears ? That's caused by the fan hitting the water, which unbalances it. StuRat (talk) 04:22, 7 July 2012 (UTC)

While we have squirrels here in Australia (they aren't native - it appears they escaped from zoos), I've never tried grinding one with gears - I'm not at all sure what that would sound like. But a fan hitting water certainly would make an obnoxious noise. You must have really strange aircons in America! Although an electronics engineer by qualification, I have ~10 years experience as a building/property manager, so I do know a thing or 2 about airconditioning - I've spent lots of employer's money on them, inspected installations, issued tender specifications, etc. I've never seen a fan deliberately used to sling condensate water, and I have seen the innards of lots of Australian, Japanese, and Chinese made unit aircons. And with all of them, unless they are worn out, all you hear is the soft sigh of air being blown, and maybe a bit of compressor noise if it is old and doesn't use a rotary or scroll compressor. Not only the fan slingling water would be noisy and vibrate your wall, it would be a health hazzard. You sure yours isn't faulty? Ratbone121.215.60.81 (talk) 05:13, 7 July 2012 (UTC)

Well, I'd call the design faulty, even though it is "working as designed". I'm not sure if you can get a window A/C unit here that doesn't use this annoying little cheat. Looks like we both learned something new today. You learned that this method exists, and I've learned that it's not ubiquitous. StuRat (talk) 07:33, 7 July 2012 (UTC)

Come to think about it, this sound is so common here, that if any window A/C unit didn't make this annoying noise, an American might think it was broken and return it. StuRat (talk) 07:42, 7 July 2012 (UTC)

Just in case you're not conviced that the slinger ring exists: "Water hitting condenser fan blade ? This is normal. Most window ac's have what they call a slinger ring. It's a ring that runs around the outer edge of the condenser fan blade and slings water up on the condenser coil to help it cool better." [22]. Here's a pic of a fan with a slinger ring: [23]. StuRat (talk) 07:52, 7 July 2012 (UTC)

Yep, Stu, we've both learnt something. After looking at your links I did a bit of googling, which perhaps I should have before. I learnt several things that may be of interest to you: (1) Slinger rings are covered by US patent 7398654 issued to LG Electronics, a Korean company, in 2002. This is at about the time I left employment having to do with airconditioners, so that's why I had never heard of it. (2) Since a slinger ring must necesarily be on the CONDENSOR fan, and the condensate water comes form the evaporator, on the room side of the internal partition, there must be TWO water trays, an "inside" one and an "outside" one, and a communicating port to give gravity flow of water from the inside tray to the outside tray. (3) the slinger ring is specially shaped and dimensioned to pick up water by viscous attachment, not scooping, and so causing a minimum of noise and vibration.

From this, I infer the following (bear in mind I've never seen such a thing):- (a) If yours makes an annoying noise, it could be because the communicating port is blocked, leading to the INSIDE tray becoming overfull, and the EVAPORATOR fan/blower blades hitting water. Blockage could be due to insects if the airconm has not been used for a while, or you have had a period of very low humidity weather. Since the evap fan is not designed for it, you will get a lot of noise. (b) the operation of such a system is dependent on humidity. In climates combining high temperatures and high humidity, the production of condensate could overwhelm the communicating port, again leading to the EVAP fan hitting water. In such climates I expect that the installer is supposed to fit a good old drain hose. In any case, if you don't like the noise, fit a hose - end of problem. (c) The patent provides for more than one slinger ring. This could allow wasps to set up their mud homes between the rings. This would give a scooping effect, resulting in much noise and vibration. Ratbone124.182.21.29 (talk) 09:46, 7 July 2012 (UTC)

I really don't think there's anything wrong with my A/C, as every window A/C I've ever seen makes the same annoying noise. I'm a bit skeptical about this "viscous attachment"; when a rapidly moving disk attached to fan blades hits water, it's going to splash, and cause an imbalance in the fan, both of which create the characteristic (American) "window A/C noise". Perhaps with a slower disk, lacking fan blades, and a thicker fluid, like oil, you might avoid this. StuRat (talk) 02:18, 8 July 2012 (UTC)

The patent description implies a slinger ring that is actually a flat disc continuously immersed, so yes, there should be no splashing, only fine droplets thrown up. Ratbone121.221.221.138 (talk) 06:56, 8 July 2012 (UTC)

I'd call slinging fine droplets "splashing", as it will make some sound (imagine a dripping faucet, now crank the speed way up). A full disk, versus the fan-disk hybrid I showed, might be better, but still not silent. StuRat (talk) 17:42, 8 July 2012 (UTC)

<undent>My mid-1980s-vintage Gibson A/C unit has a slinger ring: I suspect the LG patent is intended to address the annoying noise issue rather than the entire slinger ring concept. The Gibson makes a particularly vile splashing noise on start-up. As Ratbone speculates, there's an insulated tray that collects condensate on the evaporator side, and it dribbles through a small channel to a sump on the condenser side, into which the ringed fan dips. I suspect that much of the effect depends on the local humidity: here in the US mid-Atlantic, summers are insanely humid and there are great quantities of condensate available. Acroterion (talk) 03:23, 8 July 2012 (UTC)

Kayaking and physics

When I'm teaching kayak skills to children, I sometimes fill an idle moment by showing them the "helicopter turn" in which you spin your paddles around above your head, which causes the kayak to rotate in the opposite direction - rather pointless but quite amusing for a short while. I tell them that this is because every action has an equal and opposite reaction, a fact dimly remembered from school many years since. However, last night, a Scout Leader told me that it was caused by "conservation of linear momentum", a concept that is entirely unknown to me. Was he right and if so, what does it mean? Alansplodge (talk) 21:39, 5 July 2012 (UTC)

Actually, it would be the "conservation of angular momentum" (spin momentum). In simple terms, a new rotation in one direction must be countered by a rotation in the opposite direction. The kayak will rotate more slowly, though, both because it has a higher mass, and because that mass is farther from the center (the term for this combination of mass and distance from the center is the moment of inertia). However, this is really part of the "every action has an equal and opposite reaction" rule, which is the third of Newton's laws. To put it in a math formula, we'd have:

Ipωp = Ikωk

Where:

Ip = moment of inertia of paddle

ωp = rotational velocity of paddle

Ik = moment of inertia of kayak

ωk = rotational velocity of kayak

Unfortunately, the moments of inertia aren't that easy to calculate, and vary depending on the axis of rotation, so you probably can't apply this formula yourself. StuRat (talk) 21:45, 5 July 2012 (UTC)

the conservation of momentum (angular and linear) and "Newton's third law" are the same. Newtons laws talk in terms of forces. You carry out some action (apply force) on a body and it gives you and equal and opposite reaction ( a force on you). If you apply Newton's second law (Force=mass*acceleration ) on both the body and yourself to see how much both of you accelerated you can calculate how the two of you will move. A neater way of getting the final velocities of both bodies is to skip forces altogether and just say that momentum is conserved (Mass₁Velocity₁=Mass₂Velocity₂)

Here is a small derivation showing their equivalence-

Force₁=Force₂ (Newtons 3^rd law)

Mass₁Acceleration₁=Mass₂Acceleration₂

If force is applied for time 't'

Mass₁Acceleration₁t=Mass₂Acceleration₂t

Mass₁Velocity₁=Mass₂Velocity₂ (because acceleration*time=velocity)

Depending on the circumstance, you will use one or the other to predict how they will move. for example, when a bullet leaves a gun, the forces applied by the explosion on the gun, the bullet and the gasses of the muzzle flash are really hairy. So you just invoke conservation of momentum to calculate the velocity of the bullet or the gun recoil. On the other hand, in your kayak example, the moments of inertia and the frictional forces are really complicated. Some of the angular momentum is absorbed by the water and some by the air; though momentum is conserved, it is conserved in the air-paddle-person-kayak-water system. measuring how its distributed is really tough. ( I_paddleω_paddle + I_airω_air = I_kayakω_kayak +I_waterω_water ) Hence its just simpler to solve it by using newtons laws and correct the two forces by easily measurable frictional force.

Staticd (talk) 13:36, 6 July 2012 (UTC)

I was ignoring the angular momentum of air and water as insignificant. I still consider the air to be insignificant, but the water may make a noticeable difference. StuRat (talk) 02:12, 7 July 2012 (UTC)

You can see a video of the same kind of thing [24]. When the wheel spins one way (in the horizontal plane) the chair spins the other. Chris (talk) 20:36, 6 July 2012 (UTC)

Thank you all - I got most of it. Good old Isaac. Alansplodge (talk) 00:51, 7 July 2012 (UTC)

Resolved

LHC energy compared to mosquito

Using data from here: http://www.speedofanimals.com/animals/mosquito and here http://en.wikipedia.org/wiki/Orders_of_magnitude_%28mass%29 I compared the energy of a mosquito with the energy of the LHC at cern (4 TeV). I got 2.242 * 10 ^12 eV = 0.2 TeV for the mosquito. Is this realistic? --helohe (talk) 21:49, 5 July 2012 (UTC)

2.242 * 10¹² eV would be 2 TeV, not 0.2 TeV, but yes, I think that's about right. You can find a lot of similar claims in a search for lhc mosquito. -- BenRG (talk) 22:52, 5 July 2012 (UTC)

This LHC outreach page provides some other comparisons to macroscopic objects and phenomena to give an idea of the total (rather than the per-particle) beam energy. Running full-out, the two LHC beams contain enough energy to melt nearly a ton of copper, or to accelerate a TGV (high-speed train) to 150 km/h. The LHC's 'beam dump' system is a rather interesting bit of engineering in itself: a seven-meter cylinder of graphite in a water-cooled steel shell, contained within 750 tons of iron and concrete shielding. TenOfAllTrades(talk) 13:17, 6 July 2012 (UTC)

What sort of eye color is considered black?

In several books I've read there are characters with black eyes (mostly it's American Indians and other dark skined people who have them). I find this quite hard to picture as long as aniridia is not in the picture. I did look in the article on eye color, but it mentions no such color. So is black eye color even possible? If not then what is it - extremely dark brown? If so, how dark? ~~Xil (talk) 22:21, 5 July 2012 (UTC)

I think it is extremely dark brown, and it's so dark that it looks black. I had a friend with eyes like this, she was from the Dominican Republic. 109.97.163.148 (talk) 22:44, 5 July 2012 (UTC)

My wife (75% Han Chinese, 25% North Korean by ethnicity) has "black" eyes. They're just really dark brown such that under normal lighting and distance conditions you can't see the pupil boundaries. If you got up in her face with a pen light you'd have more success. The Masked Booby (talk) 01:53, 6 July 2012 (UTC)

I had girlfriend (part italian, part asian) once, whose eyes looked black in most indoor lighting conditions, but were actually very dark brown. Really really pretty. But nearly impossible to tell what mood she was in. Ratbone120.145.45.13 (talk) 03:12, 6 July 2012 (UTC)

If you're basing your interpretation of your girlfriend's mood purely on pupilary reflex, I think you're in for trouble from the start! Snow (talk) 05:18, 6 July 2012 (UTC)

Black eyes are really more purple than anything else, at least at the start. As they heal, they turn sort of greenish, then light yellow, then fade back to normal skin tone. --Trovatore (talk) 05:25, 6 July 2012 (UTC)

That is not what the OP wanted to know. He wanted to know about people with black iridia in their eyes. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 05:32, 6 July 2012 (UTC)

Very funny. I had thought that explictly stating eye color will suffice and I don't need to state that it is not about hematoma, rather about melanin concentration in iris and possibly human races. I merely figured that it might be some other dark color or indeed something more black looking. So from answers I take it's something like this example from that article? ~~Xil (talk) 08:04, 6 July 2012 (UTC)

A documented side effect of eyedrops for glaucoma e.g. Xalatan is darkening of the iris which I have observed approaching brown-black like in this. DriveByWire (talk) 12:10, 6 July 2012 (UTC)

Academic sources for nutrition

I'm looking for information relating to nutrition. I'm having trouble finding sources which aren't inherently biased and/or low quality. I'm looking for something like PubMed for nutrition, where high quality, technical information is discussed objectively without promoting a particular view. Searching google scholar, I can find some information, but the content is usually too specific (for example, discussing nutritional deficiencies in a particular group studied, or the production process of a particular food).

As one example, I'm trying to compare the nutritional value of cow's milk with almond milk and soy milk. On google, "almond milk vs soy milk vs cow milk" yields sources all saying different things. Result 1 is MSNBC, which says cows milk wins in just about every category. Results 2-4 say the opposite, but even they don't seem to match up in details; (2) is a forum post, (3) is selling organic products on amazon, and so forth. I was recommended sites like "almondmilkbenefits.org", an obviously non-neutral source with an anonymous author. On google scholar, searching for "almond milk" gets nowhere close to nutrition. Our own article is extremely lacking.

Is there a good place to find this information? I'd be happy with anything from a basic summary (supported by sources) to in-depth scientific papers. I just want something on the topic that I can trust, and potentially then use on wikipedia to meet, say, WP:MEDRS. Thanks!   — Jess· Δ♥ 23:35, 5 July 2012 (UTC)

PubMed is for nutrition. Do you know how to select the WP:MEDRS sources, e.g., the reviews and meta-analyses? They recently changed it again. PMID 22331683, PMID 17410674 (similar title, different author), and PMID 12487214 might be good places to start, although that last one is probably more for infants than adults. 75.166.192.187 (talk) 00:26, 6 July 2012 (UTC)

Unfortunately this whole area is plagued by weak science, and there is no absolutely reliable source of overview information. The best thing I can suggest in general is to use PubMed or Google Scholar to locate information, but then you will have to judge for yourself how much to rely on it. Looie496 (talk) 01:28, 6 July 2012 (UTC)

http://www.ajcn.org/ Count Iblis (talk) 02:27, 6 July 2012 (UTC)

I find http://www.nutritiondata.com to be useful. (They have nutrition info on soy milk and cow's milk, but don't seem to have any on almond milk, yet.) And, while that site gives far more info on the products they analyze, just reading the labels gives you a fair amount of info for a comparison. StuRat (talk) 06:55, 6 July 2012 (UTC)

July 6

Angiosperms

Bay Laurel magnolia laurus nobilis virginiana, a flowering angiosperm.

Angiosperms are commonly known as what plants? — Preceding unsigned comment added by 175.137.136.244 (talk) 03:38, 6 July 2012 (UTC)

Flowering. 75.166.192.187 (talk) 03:41, 6 July 2012 (UTC)

Oh, are we playing Jeopardy? ~sniffs disdainfully at the IP who answered first but failed to do so in the form of a question~ What is a flowering plant, Alex? Snow (talk) 05:05, 6 July 2012 (UTC)

I thought Jeopardy clues didn't have question marks?A8875 (talk) 05:27, 6 July 2012 (UTC)

That's true - the full Jeopardy formula would produce something along the lines of "These plants, classified as angiosperms, are better known by this common name." But you can't deny that this seems to be more of a quiz than a refdesk question, since the OP obviously knows the answer. And he even gave us a picture assist as they occasionally do on Jeopardy, I seem to recall. :) Snow (talk) 08:13, 6 July 2012 (UTC)

OP didn't add the picture, 75.166.192.187 added the picture along with a response. I agree OP was probably quizzing us. His reasons for doing so is unfathomable to me. A8875 (talk) 09:00, 6 July 2012 (UTC)

Maybe he just wants to participate. ;) Snow (talk) 10:50, 6 July 2012 (UTC)

I need to know

I am not quite sure of my religion, nor my beliefs. Only that I have so many questions that I want to ask but yet to have found answers. I just don't understand how some one could believe that out of nothing, pure NOTHING. blankness, nothing. NOTHING! Something called "God" appeared, or apparently always was... I don't get it. So, in my head i picture whiteness. Nothing but pure whiteness. A blank screen. And then there is "God" who apparently has always been in this pure nothingness. And out of all that nothingness, "God" created everything. Put the world through cycles.. Then had Mary and Joesph birth his son, "Jesus". And "Jesus' carried his word thru out the world. the world advanced and this is what has become of it. How do we know that Heaven and hell exist? we would only know if we had died, and no one can die and then come back and tell us that its real... With the way the government hides and lies to us, it's hard for me not to think this is just another scam they have. If so, i believe its a sick joke.. Like I said, I never said I don't have FAITH, I just don't understand.. Every time I ask these questions every one yells at me and says I am not a believer and that because I want to know these things I don't believe in god. I just want to know where God came from, and how we managed this. And if he created human, what is he? Or she? How do we know any of this is real? I just want to know.. and I know I probably won't get much of an answer back. But, it's worth a try. i am just a very factual person, I need facts. I love science and it's getting in the way of having complete and udder FAITH in this mystical creature who has always existed in pure nothingness, that has some sort of power to be able to create the Earths, the Heavens, the Hell's, and so on and so on. Time and space, god is above that? How can we explain that God is above time and space. Doesn't that sound more scary then good? I don't know.. He has this infinite power, that controls everything. He knows everything you think, everything you do, and he takes all your actions upon you at the day of your death to decide whether you go to hell or you come to heaven. What if because I have these questions, and these doubts that I go to hell? I have a question and that makes me wrong? I want facts, and that makes me a sinner? I want to know where this something came from that I am supposed to believe is almighty, and I am sent to hell? That's cruel. I am sorry, but if because I have questions about this, and it condemns me to hell, God sounds more like he is a punisher rather than our savior. — Preceding unsigned comment added by Aantoinette (talk • contribs) 05:25, 6 July 2012 (UTC)

Which is how we know that God does not exist. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 05:29, 6 July 2012 (UTC)

A couple thoughts:

1) Both science and religion have the same flaw, in my opinion, that neither can tell us what happened before a certain time (The Creation/Big Bang). They can say that God/the universe always existed, but that's just as bad of a cop-out, to me.

2) I find Eastern religions, with their balance of good and evil gods/forces to be a better explanation than the Abrahamic religion concept of a single, infinitely good, and infinitely powerful God. Clearly, evil happens in the world, and so God either can't prevent it, or doesn't want to, which makes him either not infinitely powerful or not infinitely good. StuRat (talk) 05:34, 6 July 2012 (UTC)

Aantoinette - you say that you do have faith, but "Every time I ask these questions every one yells at me and says I am not a believer and that because I want to know these things I don't believe in god." It sounds like you may be surrounded by some pretty intolerant people. And I wonder what you do have faith in? Keep asking the questions, but not among those with unquestioning minds themselves. HiLo48 (talk) 05:58, 6 July 2012 (UTC)

StuRat, I think you are confused about science. No real scientist will say that the universe has always existed, it began about 13.7 billion years ago. As far as "before" the beginning, the consensus seems to be that asking "What happened before the Big Bang?" has no meaning; it's like asking "What's south of the South Pole?".

Science has its flaws, but comparing to religion is pointless. To paraphrase Tim Minchin, science is formulated based on observations; religion relies upon the denial or absence of observations to preserve faith. They are incompatible systems, and I for one am a fan of the one that invites skepticism and allows anyone to test and verify the results, not one that quashes dissent and forces uniform belief based on nothing but faith.

To the OP, if you're looking for religious guidance, I think you have gone astray by asking at the Science Desk.-RunningOnBrains^(talk) 06:09, 6 July 2012 (UTC)

I believe some scientists have speculated about what happened before the Big Bang. There was the oscillating universe theory, then there are more modern cyclic model theories, and a multi-verse theory which proposes that big bangs are going off all over the place, creating their own universes, perhaps each with slightly different string theory parameters. StuRat (talk) 06:43, 6 July 2012 (UTC)

For Stu's claim, it's yes and no. Any serious theory that provides a "before" to the big bang still has to come to grips with a beginning at some point. Except for Hawking's theory, which many physicists agree with, in which time began with the big bang. In this formulation, there was no "before". Hawking then waves his hands (or he would, if he could), and declares that no moment of creation is required, nor anything previous. I don't have the physics expertise to understand and evaluate his idea. Someguy1221 (talk) 07:19, 6 July 2012 (UTC)

Yes, actually some of those theories have seen a resurgence of late, now that computational processing has become so powerful that the list of candidate contour models for dimensional variation at the string-scale has grown to an astronomical size. The idea of co-existent multiverses is an elegant solution to the question of why our universe happens to exist within its set constraints, but it's highly speculative. Now that the standard model is nearing complete validation (or as complete as its likely to get, in any event), it will be interesting to see where research in this area heads, since string theory is such a prominent contender as a unified field theory. Snow (talk) 08:59, 6 July 2012 (UTC)

The problem with Stu's analogy is that he compares a first order assumption with an extrapolated assumption. The universe exists, we know this for a fact as it is simply the name we give to all of the collective phenomena which compose the observable existence around us and - baring certain abstract spiritual, existential, and metaphysical arguments - we make this a basic assumption of all further arguments about its nature, such as whether it has always existed or has a definable age. This is a very different issue from the question of whether God exists, which is not an empirical first-order assumption since we stipulate existence anytime we engage in observing any principle, phenomena, or issue. Snow (talk) 08:41, 6 July 2012 (UTC)

Dear OP: You seem to have absorbed a second-hand folk version of both Christianity and scientific cosmology. My advice to you is to read and absorb what's been said above to understand more about the Big Bang. (The 'nowhere south of the South Pole' explanation makes sense to me and accords with my understanding of what Hawking et al have said.) For the religion questions: break them down into smaller units - 'Is there a God?' 'Who was Jesus?' 'What, if anything, can the historical Jesus (if there was one) tell us about our lives today?' 'Does belief in God and/or Jesus require belief in Heaven and Hell as they have been explained to us by the churches?' 'Does a belief in religious morality necessitate a belief in Heaven and Hell? How about vice versa?' 'What other religious paths are there, and what are their merits and problems?' If you want to know what others have said on these topics, try researching, or asking on the Humanities desk. Heck, I'm happy to discuss this stuff on my talk page. AlexTiefling (talk) 10:31, 6 July 2012 (UTC)

All good advice, though I suspect the OP is probably already well on her path towards an agnostic/atheist perspective if she feels such a strong disconnect with the dogma she is familiar with and what seems intuitive to her, despite the fact she is apparently surrounded by religious fundamentalism in her daily life. She also seems to prioritize the value of the empirical process which, although not necessarily mutually-exclusive to religious faith, often takes root in a certain type of person and fills the basic role of central guiding principle that religion serves in many others. Snow (talk) 10:48, 6 July 2012 (UTC)

Oh, I agree. I'm not suggesting that responsible answers to the proposed questions will lead anyone to adopt or re-confirm a religious faith. Rather, those are the sorts of questions to ask (along with 'says who?') in order to tease out what we understand by religion at all. Asking them in the enquiring and empirical spirit you suggest is a good idea. AlexTiefling (talk) 11:33, 6 July 2012 (UTC)

Yeah, I know, I caught your meaning, and you're right, she'll have to deconstruct things to make sense of them and decide how much, and how quickly, to transition from her current beliefs. I just mean to add by way of addendum that if she's as incredulous about those concepts as she is already, she might go very quickly from the "How does this really add up?" stage to the "Yeah, I'm over it entirely - let's hear another perspective" But who can say for sure? Snow (talk) 13:30, 6 July 2012 (UTC)

Much of this is beyond what science can answer - but at least note that the rule with science is that when you try to penetrate to the very truth of things, things get weird. The Big Bang is a mathematical breakdown in calculations; it's not actually a model for something from nothing. It might be saner to use the logarithm of "time", as we define it, from the Big Bang until today, in which case there is no beginning. And in the Copenhagen interpretation of quantum mechanics, one can argue that there was no "collapse of the state-vector" before conscious observers - that in fact, before the advent of man, the universe was a superposition of countless states, and only when first he looked up to the sky were the positions of the stars determined. That's not even getting into high but perhaps purely hypothetical weirdness of Membrane (M-theory). So if you get the feeling that science has to give you some simple, comprehensible answer about the first origins of things - don't count on it! Wnt (talk) 12:35, 6 July 2012 (UTC)

Well not in our lifetimes anyway. But the OP doesn't seem to me searching for absolute resolution to any question so much as questioning the foundation of explanations that have been given to her in the past. Even when science -- or more broadly empiricism, since we're not talking about formal processes alone here -- fails to give us complete answers or leaves us with more than we had when setting out to a resolve an issue, it can still be a comforting and rewarding process. It's dependable, even though it doesn't give us the answers we expect or want. I suspect that this is what the OP is trying to suggest she gravitates toward - that sense that, even if science/empiricism doesn't give us everything all at once, at least it gives us a framework that we feel we can build from, constructing larger and more complex principles from more basic ones and having it feel consistent, verifiable and honest. It's predictive and explanatory capabilities may not be unlimited, but it's better than taking on faith ideas which you feel are inconsistent with the world as you've observed it to operate. That's really the OP's only other choice in the context she's described. Snow (talk) 13:14, 6 July 2012 (UTC)

To the OP, I have more of a practical recommendation for you than an answer to any of the particular issues you raised. Try finding a copy of Carl Sagan's Cosmos. It's a simply brilliant work which examines many of the concepts you're wrestling with but, more broadly, is simply an excellent primer to the scientific method and how it has slowly evolved to tackle issues of both cosmic and human scale. Sagan had an ability, which I have never seen surpassed in my lifetime, to distill complex ideas down to their elementary points in a way that is exceptionally clear and accessible to almost anyone and yet is also undeniably poetic. You could certainly do a lot worse as a place to start for someone who's trying to understand the big picture and begin to put human experience in perspective with regard to the enormity of the universe. It's a little dated at this point (visually I imagine it will look almost archaic), but it could give you a good leg up in tackling your nagging questions. Trust me, you're gonna thank me.  :) Snow (talk) 13:50, 6 July 2012 (UTC)

And there's also the accompanying book, if you prefer reading over watching. StuRat (talk) 02:19, 7 July 2012 (UTC)

Time doesn't exist in the first place. There only exists a multiverse, which is a timeless entity. Count Iblis (talk) 15:29, 7 July 2012 (UTC)

Ethics is more important than religion. Do you want to believe in a God who would command you to sacrifice your firstborn son to test your faith? My God is neither evil enough to do that nor too stupid to have understand evolution. Figure out what you believe in and then pick a God who lives up to your expectations. μηδείς (talk) 23:46, 7 July 2012 (UTC)

Extreme weather damage

What is the best way to characterize the two graphs here? I've asked for help at commons:Commons:Graphic Lab/Illustration workshop#Extreme weather damage to combine the two graphs, and that would be great, too, but what is a fair summary of the both of them in words? 75.166.192.187 (talk) 05:59, 6 July 2012 (UTC)

They both indicate increasing damages from storms. However, I'd stick with the raw data, and avoid those lines and curves they added. Especially on that first graph, those lines look rather suspect. First there's the assumption that any change would be linear. Then there's the actual fitting method they used. And I suspect that they intentionally chose a year of low storm damage as the starting point, to make it look worse. The red line, in particular, seems out of place. It shows a 50% increase in earthquakes, tsunamis, and volcanic eruption, but why would any of those be caused by global warming ? I'd leave that off the graph entirely. Also, since they mean to rule out natural cycles, they should show them on the graph, in particular El Nino, and perhaps the sunspot cycle, since that might affect electrical storms. Also beware that monetary damage from storms is affected as much by poor construction decisions (where they build and how they build) and the economy (property values) as it is by the weather. StuRat (talk) 06:22, 6 July 2012 (UTC)

(edit conflict)

If I had to characterize the first chart, it seems to be almost pseudoscientific. What characterizes an "event", exactly? What is a "mass movement"? What is a "storm"? Why are non-meteorological geologic events included in this graph? This is a bunch of nonsense to try to find certainty where there is none. The second graph is begging the question as well; of course storm-related damage is going to increase as the GDP and population increase, in addition to the spreading of population into more disaster-prone areas. It conveniently omits hurricane damage to focus only on thunderstorm damage because 2011 was an extreme year for tornadoes. If you normalize the data for population and wealth changes, the chart would probably look more like this chart of hurricane damage, which shows no significant trend.

These authors are clearly into the climate change debate politically and not scientifically: they are mining for "scientific data" to support their conclusions, disregarding any other data. Dishonest science is dishonest science, no matter what side they're arguing for. Data may overwhelmingly point to a warming planet, but science still can't say anything for certain about its implications for small-scale events like tornadoes, hurricanes, and other storms. I would say that if you want an honest assessment of scientific views on climate change, our Global warming article is actually pretty well-done. -RunningOnBrains^(talk) 06:26, 6 July 2012 (UTC)

Agreed. Note that the Huffington Post is a liberal web site, and, as such, they don't provide unbiased news. Neither do conservative media outlets, like Fox News. I'd stick with data provided by scientists who aren't on the payroll of either liberals or conservatives. StuRat (talk) 06:34, 6 July 2012 (UTC)

Both of the graphs claim to be from Munich Re, and in both cases the y-axis is financial damage, over time. I am not asking about the bias of the publisher, only the reinsurer's graphs. 75.166.192.187 (talk) 07:02, 6 July 2012 (UTC)

You asked for how we would characterize the charts...I replied that I would characterize them as pseudoscientific and/or misleading. That's the answer. I can't come up with a "fair summary" of something that appears to be vague at best, nonsense at worst. As far as the second graph: without knowing what they mean by "thunderstorm insured loss" (does this include tornado, wind, hail, lightning, flooding, or some combination?) I can't give a "fair summary", as you say.-RunningOnBrains^(talk) 08:12, 6 July 2012 (UTC)

Munich Re has a fiduciary duty to accurately report insured losses, and a legal obligation to provide an honest assessment of how they see the future of their insurance business, otherwise their shareholders could sue them. So I would assume their data is accurate as to their business. If what you care about is their business, then that is fine. That said, the graphs may be misleading about the underlying climate trends because of confounding factors like population growth in vulnerable areas, changes in property values, changes in the number of policies written by Munich Re, and other factors. One is likely to get more useful information about climate by looking at climate / weather patterns directly (e.g. number and intensity of storms over time). Dragons flight (talk) 21:10, 6 July 2012 (UTC)

This is probably a better way to say it than I did. Certainly the charts may have legitimate uses for actuaries and insurance companies, but without knowing more about what data they are plotting the graphs are useless.-RunningOnBrains^(talk) 21:44, 6 July 2012 (UTC)

Okay, given all that, and assuming only [25] and [26] are accurate, what is the correct way to characterize their data? Also, what does the ratio between earthquakes and weather events say about the extent to which population shifts are responsible for the characteristics of the data? 75.166.192.187 (talk) 23:24, 6 July 2012 (UTC)

Well, the lines on the first graph simply aren't described in the key, so we can't tell if they are least sum of squares calculations, or what, or even if all the lines are calculated in the same manner, or perhaps just drawn in by hand with no calculations behind them at all. But, if you did take them to be accurate representations of the overall trend, and if you assumed that the 50% increase in earthquake/tsunami/volcanic eruptions was due to the increases in population and property values in dangerous areas, and if you assumed that the same changes also occurred in population and property values in areas affected by climate-related disasters, then you could do some math.

Since 100% is 2/3 of 150%, you could then multiply that 2/3 by, say, the 300% in a climate-related category, and get 200%, meaning that the damage doubled in that 30 year period for reasons other than population growth and property value increases. I'm sure you will assume this is due to climate change, but we really can't tell that from this data alone. StuRat (talk) 02:04, 7 July 2012 (UTC)

What additional data do we need to know to isolate the proportion of the increase due to increasing extreme weather instead of population shifts? Would it be better to plot either or both graphs on a log scale y-axis? 71.212.249.178 (talk) 06:03, 8 July 2012 (UTC)

You want to have actual data on the population growth and changes in real estate values in the areas in question. For example, if you are looking at damages in Dade County, Florida, what has been the population change and real estate value change in Dade County over that same period ? Of the two, real estate value change is the more important, as presumably the population change will be reflected in that. Once you have that, you can adjust the damages, just as I did above by assuming that non-climate changes represented changes in population and real estate values. StuRat (talk) 06:12, 8 July 2012 (UTC)

Calcium-48

How is calcium-48 produced for the experiments making superheavy elements? Is it simply separated out of natural calcium? If so, how is it separated? (Cites please, because I'm putting this into an article – ununseptium – which is currently at GAN.) Double sharp (talk) 14:22, 6 July 2012 (UTC)

I can find several references to different methods, but nowhere does it state which (if any) are preferred. Chemical processes seem to be the most-referenced, especially chemical processes involving crown ethers and chemical processes involving sulfonic acid. This book notes that the "liquid thermal diffusion" method may be feasible, but doesn't address calcium-48 directly for this method; it also notes that mass spectrometry (specifically using the Calutron) is less feasible for Ca-48 because it takes far longer than other methods. Single-photon atomic sorting is proposed as a method for sorting Ca-44, but I believe it only works on certain isotopes and would likely not scale to Ca-48. This NASA technical paper might also contain helpful information judging by the title, but it's not available online so you'll have to request a (free) copy. -RunningOnBrains^(talk) 22:09, 6 July 2012 (UTC)

Detonator ?

Hello learned ones ! How do you call the wooden box with a handle Cl Nicholson falls on, triggering the blowing up of the bridge, in the film « Bridge on the river Kwai » ? Some around me tell me it's a detonator, but I thought detonators were crayon shaped and sticking to the dynamite baton (the kind of little thing which explodes in his lap & disembowells the young Arab , close friend of Lawrence, in the film « Lawrence of Arabia »...) . Thanks a lot beforehand for your answers ( & sorry if my cinema references are a bit outdated...But so is the wooden box with a handle, isn'it ?... Arapaima (talk) 16:00, 6 July 2012 (UTC)

The short answer is that those are both detonators, as are the small devices that used to be placed on railways tracks to provide emergency warnings. Anything which causes a detonation is potentially a detonator, although it is common to restrict this to mechanical devices, and call the chemical ones fuses. AlexTiefling (talk) 16:04, 6 July 2012 (UTC)

The stereotypical box with the plunger is not a detonator. A detonator is a device that contains primary explosive wich explodes to initiate the detonation of the main explosive. The box with the plunger is an electrical generator that provides the impulse to the detonator to make it explode. Roger (talk) 17:10, 6 July 2012 (UTC)

So that box is a magneto ? Thanks a lot Alex & Roger . Arapaima (talk) 17:44, 6 July 2012 (UTC)

I think the more modern ones contain a battery, and the plunger closes a contact, connecting the battery to the explosives by wire. StuRat (talk) 18:21, 6 July 2012 (UTC)

Related to a detonator, a blasting cap is a small explosive device that triggers a larger one. That might be what you saw in Lawrence of Arabia. StuRat (talk) 18:21, 6 July 2012 (UTC)

Yes, to differentiate it from others its better known as a 'plunger detonator.' It's mode of operation is that the spring hold the plunger up against the 'shorting link' which guards against induced currents from nearby electric storms and such like from initiating an unscheduled detonation. Quick depression of the plunger, spins a magneto which charges a capacitor and at the bottom of the stroke, a pair of contacts discharges the stored energy down the wires to the explosive detonator charges. As the magneto has mass, a far mount of force is required to be applied perpendicular to the base, in order to spin it up from stationary. Therefore, either Colonel Nicholson intentionally fell onto the 'plunger detonator' squarely and thus avoiding it tipping over or Alec Guinness stumbled onto a cheaply made film prop or possibly both. Other types incorporate a crank handle to turn the magneto (like the old telephones one see's in old movies) to charge the capacitor and separate switches to set the circuit and a button to fire. All done without the need for batteries. They don't tend to have enough energy to set off more than one detonator on a long cable run.--Aspro (talk) 18:25, 6 July 2012 (UTC)

Apropos your first two sentences Aspro, see here for the usual disambiguation. DriveByWire (talk) 21:38, 6 July 2012 (UTC)

Thanks, You have confirmed my suspicions that I knew there was no point in reading things like Eats, Shoots & Leaves when I have volunteers like you to correct my punctuation. Tell me, is there one or two t's in pedantic? [27] :¬) --Aspro (talk) 22:04, 6 July 2012 (UTC)

StuRat is, as is often the case, partly right. The modern equivalent of a plunger detonator are indeed battery powered. The one I have used ran off 4 1.5V "D" cells, and contained an electronic invertor to charge up a capacitor, just as the old plunger-generator types did. So there is no plunger, as there is no generator to turn. To set of the explosives, you insert and turn a key (which was spring loaded to the off/safe position) to activate the invertor, and then push a button to detonate. This gives equivalent safety against accidental detonation (detonation circuit is safe until button pushed, system requires two hands in a deliberate action). Actually, its a bit more safe, as only the licenced powder monkey has the key. Keit124.182.149.215 (talk) 02:07, 7 July 2012 (UTC)

There's nothing outdated about Lawrence of Arabia. David Lean considered it his finest achievement, and millions of movie-lovers have agreed with him. Montgomery Clift, Anthony Perkins, Marlon Brando and Dirk Bogarde were all seriously considered for the title role. Bogarde fought to secure the role, and regarded the studio’s rejection of him the greatest disappointment of his career. It was offered to Albert Finney and Richard Burton, who both declined it. It finally went to a virtual unknown, Peter O'Toole. If you’re below a certain age, these names might not mean a great deal to you, but this was a very big deal (boy, that really dates me). It’s probably time for a remake now. Not to prejudge anything, but it will not be as good as Lean’s film. -- ♬ Jack of Oz ♬ ^{[your turn]} 04:12, 7 July 2012 (UTC)

That's a bit like saying "Nothing personal, but you're an (insert unrelenting stream of insults here)." :-) StuRat (talk) 04:37, 7 July 2012 (UTC)

Thank you for the interesting aside about an epic film classic. LoR is a 50 year old film about events 95 years ago, reflecting a different political and technical world than encountered today. Thus it is dated if not outdated. Here is an antique blasting machine. DriveByWire (talk) 13:28, 7 July 2012 (UTC)

Here is another opinion on the name of the device: "blasting machine". It's got a picture of Wile E Coyote so it must be the real thing. Googling suggests that "blasting machine" is still a current term in the industry, and is used for the modern solid-state types as well as the iconic generator type. See this commercial website for example. --Heron (talk) 10:07, 7 July 2012 (UTC)

Thanks awfully to all ! Why dont you write an article "Blasting machine" in WP en, I'll be glad to translate it into french. Jack, I'm not too young to know the actors you mentionned, I even saw "L. of Araby" when it came out, and again several times (on a wide screen) in the past decades. And I think it has not a chance to be done again, thanks godness...Glad my question arose your interest. See you, Arapaima (talk) 15:51, 7 July 2012 (UTC)

Why do consumer electronics use DC?

Couldn't they just use AC like motors, toasters, hair dryers and lamps? OsmanRF34 (talk) 16:43, 6 July 2012 (UTC)

Because the electronics you are thinking of use batteries. Batteries are DC. 148.168.40.4 (talk) 17:27, 6 July 2012 (UTC)

That isn't the only reason. Most sophisticated electronic circuits require DC in order to work. Looie496 (talk) 17:57, 6 July 2012 (UTC)

Circuits use DC from the time that consumer electronics were not portable. 79.148.233.179 (talk) 18:17, 6 July 2012 (UTC)

Also, DC is less dangerous, allowing higher amperages without risk of electric shock. -RunningOnBrains^(talk) 18:01, 6 July 2012 (UTC)

I don't believe DC is less dangerous for the same voltage + ampere. But AC is held to be more likely to stop your heart and DC is held to give a stronger "can't let go" factor. Under the wrong circumstances, either will ruin your whole day.79.148.233.179 (talk) 18:17, 6 July 2012 (UTC)

The real reason: circuits use electricity as a signal. Using AC, which per definition is alternating, it'st much more difficult, when not impossible. The examples that you cite above use electricity to move something. 79.148.233.179 (talk) 18:17, 6 July 2012 (UTC)

Semiconductor electronics intrinsically only work with "one-way" electron flow, so the "reverse" half of the AC cycle will either be wasted or destroy them. And some devices need a constant source (for example, to maintain RAM storage), so the pulsing nature of AC causes problems each time it cycles (60 Hz is too fast for you to notice your lights flickering but computers do a lot of work in each 1/60th of a second). DMacks (talk) 18:49, 6 July 2012 (UTC)

I bet there's some really wacky way to code digital bits and logic gates and so forth using purely AC current and lots of inductors... but I have no idea what it is! ;) Wnt (talk) 21:20, 6 July 2012 (UTC)

It is not wacky, merely inefficient, to store data in non-volatile RAM during an off period while a digital circuit waits for the next supply voltage pulse. DriveByWire (talk) 21:44, 6 July 2012 (UTC)

I think Wnt was referring to Magnetic-core_memory.A8875 (talk) 21:52, 6 July 2012 (UTC)

Wnt, what you are thinking of is magnetic amplifiers. It is quite readily possible to make both amplifiers and memory devices, and combinatorial logic circuits with magnetic amplifiers. See http://en.wikipedia.org/wiki/Magnetic_amplifier. Although the WP article says there is an upper frequency limit of 200 kHz, that was the technology of the day. There is in fact no theoretical upper limit, and with modern ferrites, it could go at least into the MHz region. Magnetic amplifiers use an AC power suource instead of DC, and were very reliable, but were driven out of the market by the considerably cheaper bipolar transistor, which uses DC power. Keit120.145.18.164 (talk) 04:53, 7 July 2012 (UTC)

The reason why analog electronics uses DC power and not AC power is partly historical and partly economic. Conventional electronics is based on transconductance or transresistance control - the input signal controls electrical conductance or resistance of the output circuit of the fundamental component of electronics - the amplifier. If the power source is DC, transconductance and transresistance amplifiers inherently reproduce the input signal (at the larger level) at the output. You can also build an amplifier using transcapacitance or transinductance - such things are called parametric amplifiers. Parametric amplifiers use an AC supply as their power source, but the AC source must be high frequency, not the standard 50 Hz or 60 Hz power frequency. Providing the high frequency AC power is a lot more expensive than providing DC. Parametric amplifiers have been used in specail applications requiring very low noise, and very high frequencies (up into and past the visible light region) where transistors won't work (using gunn sources and lasers as the power source), but for everything else, conventional DC powered transistor circuitry is a heck of a lot cheaper. That's the economic reason. It's much simple to undertastnd the operation of DC powered tube circuity (and transistor circuitry) than it is to understand parametric circuitry. Both are well within the capability of modern electronic engineers (I have designed and built parametric amplifiers myself, which proves it!), but in the early days of radio, it was of course the simpler techniques that got done first. That's the historical reason - the early radios set the pattern of DC powered circuits. Incidentally, the Wikipedea article on parameteric amplifiers is pretty poor - its written at an academic level so ordinary mortals won't get much from it, and it contains some serious mistakes - eg stating that a transresistance element is required - not right, and it seems to be implied that the power source must be harmonically related to the output - true only for certain classes of parameteric amplifiers. Keit120.145.195.13 (talk) 10:41, 7 July 2012 (UTC)

For the same reason a mill powered by a water wheel needs a flowing stream and not a sloshing lake. μηδείς (talk) 23:42, 7 July 2012 (UTC)

Quite apart from μηδείς not considering wave power, he's used an inappropriate analogy. The basis of electronics is amplification - creating a larger amplitude replica of the input signal. A water wheel is NOT an amplifier, it ia a hydro-mechanical transformer, in which its output power is less than the power going in. The OP essentially asked "can AC be used as a power source for electronic circuits instead of DC?". And the answer is "Yes it can, but in nearly all applications it is not cost effective, and the AC required is not the convenient 50/60Hz used in the lectrical power industry". In special applications (low noise amplification of faint signals from outer space being a fairly well known example) AC (with parametric amplifiers) IS used as the power source. Keit120.145.130.198 (talk) 03:05, 8 July 2012 (UTC)

July 7

Genetic variation between humans

A little while back, I heard someone (I believe a biologist) make the claim that genetic variation among humans was small. First, what precisely does this mean? And second, is it true? Thanks.

PS I tried reading the article human genetic variation but I couldn't find the answer I was looking for. 65.92.7.168 (talk) 02:18, 7 July 2012 (UTC)

Small compared to what? There are different ways to measure genetic variation. Read the Human genetic variation article again - it lists some of the ways. Perhaps the easiest to understand is Nucleotide diversity. The article cites a nucleotide diversity of about 0.001 for humans. I found an article that suggests that domestic dogs have about the same number. By this measure, humans contain about the same amount of genetic diversity as the domestic dog. Chimps and Bonobos also have similar nucleotide diversity, or even somewhat higher numbers than humans. The nucleotide diversity of tuna, on the other hand, is much higher, over 4%. Buddy431 (talk) 03:37, 7 July 2012 (UTC)

As you correctly guessed, by small I meant compared to comparable mammals. But I find the article's claim about domestic dogs to be very surprising. Different breeds of dogs seem so ...different, surely they would have a very high nucleotide diversity, no? 65.92.7.168 (talk) 04:05, 7 July 2012 (UTC)

Genetic diversity often does not manifest itself as obvious differences in phenotype. Among humans, for example, there is more genetic diversity within Kalihari Bushmen than across all non-African populations combined. That's a result of the ancestors of the Bushmen having been in that area for hundreds of thousands of years, whereas all non-African populations passed through a common bottleneck about 50,000 years ago. The visible differences among dogs are a result of selective breeding and not a sign of large genetic diversity -- the breeders emphasized the genes that make a visible difference and ignored the others. Looie496 (talk) 05:27, 7 July 2012 (UTC)

You can think of a human's DNA as a sequence of letters A, G, C, T, lined up in arbitrary order (like AGGCTATTACTTTACCTA...), several hundred million letters long. If you pick two people at random, their letter-sequences will match in over 99% of locations. It's in that sense that genetic variation is small. Looie496 (talk) 03:44, 7 July 2012 (UTC)

"Small" is always going to be in comparison to something else. It's certainly smaller than lay people or even new students to biology intuitively guess. It's pretty average as far as animals go. Someguy1221 (talk) 03:46, 7 July 2012 (UTC)

As for why the genetic diversity of humans would be small, it's because we have a relatively long time between generations, and are a relatively young species, which combine to mean there have been a lower number of generations than most other species. (Dogs are an exception, since we bred them from a small number of wolves, fairly recently, they don't have much more variation than those original wolves had.) Since each generation has the potential to introduce new genetic diversity, more generations mean more diversity. StuRat (talk) 07:24, 7 July 2012 (UTC)

Rather surprisingly that is not true. See molecular clock. That depends a bit on whether an animal is cold blooded or hot blooded but does not seem to depend very much on how long the generations are. Dmcq (talk) 16:20, 7 July 2012 (UTC)

I don't see how that article contradicts what I said. In fact, it agrees, listing one of the factors as "Changing generation times (If the rate of new mutations depends at least partly on the number of generations rather than the number of years)". It also provided examples of where longer generations slow the molecular clock: "Tube-nosed seabirds have molecular clocks that on average run at half speed of many other birds, possibly due to long generation times, and many turtles have a molecular clock running at one-eighth the speed it does in small mammals or even slower." StuRat (talk) 16:34, 7 July 2012 (UTC)

Actually this is an incomplete picture and the influence of generational length, in this context is not as great as you might think, though not primarily for the seasons that Dmcq cites above. The length of generations is a contributing factor, but (likely to be) a small one here, since this is not the strongest constraint on species differentiation and we know of more potent influences in the case of humans. For example, natural selection is not the only factor which could leverage such a split - Sexual selection is often a major contributor to the generation of a subspecies split -- and indeed, human beings do show some propensity for selecting mates who look similar to those they grew up around; for example, many studies have observed that couples, barring outside social pressure on the choice of their mate, tend to have amazing similarities in small details of their facial features (the width of the bridge of the nose, the relative size of the earlobes, ect.) that are incongruent with chance. This is because human beings, like many complex sexual species, imprint upon those they grow up around (parents and siblings) as their ideals for attractiveness, and, to an extent, select mates accordingly -- this is mostly what accounts for the generation of our phenotypical "races" and differences like skin color (earlier theories that these types of changes were the result of natural selection -- such as protection from UV radiation driving skin color adaptations, have been more or less debunked). However, these factors, interesting as they are, are not as firm in humans as they are in less social species -- humans apply much more complex psychological equations in the selection of their mates and (baring some historical divides) don't show much qualms in crossing those phenotypical lines (again, as compared to sexual species of similar complexity). Without the bottle-necking effect of sexual selection, homogeneity is going to increase, and indeed research suggests that at present time this is the trend, as even non-experts can see in the fact that "pure white" races are becoming a smaller and smaller proportion of the population in nations where they used to predominate. Also consider that, even with natural selection, the pressure for change is not all that great; natural selection is driven, for given species, by the adaption of beneficial traits and we've found one that has, since we adopted it, not ceased being useful in our environmental context: intelligence. Well, a specific type of intelligence -- abstract thought, and all the attendant advantages that process confers -- language, tools, and mental/practical adaptations that allow us to tackle new environments and new problems without having to develop a more specific physiological trait to cope. You're quite right to point out that humans are a relatively young species (our modern form being somewhere between 100,000 and 200,000 years old) and that we shouldn't necessarily expect differentiation in any event, but some species have cleanly split into several subspecies in a lesser number of generations than have taken place for humans in that span and the greatest constraints on our doing so moving forward are our willingness to mate freely with one-another (which seems likely at present time to only increase) and our conceptual/technological ability to adapt to new circumstances (which also will likely increase). Add to this our advancing capabilities with genetic engineering and it seems likely we will be tailoring our genes in a planned manner long before we begin to differentiate via the traditional means. Snow (talk) 19:39, 7 July 2012 (UTC)

There certainly are other factors, like isolation of populations, which affect how quickly a species splits into two or more, but, overall, I doubt if the majority of species diverge into separate species with as small a number of generations as there have been in humans. StuRat (talk) 20:31, 7 July 2012 (UTC)

Well, in most cases we don't have a completely clear picture, but 6,000 to 10,000 generations has seemingly proven more than sufficient to allow for significant divergence in other mammalian species, possibly even other primates. Consider for example the fact that we co-existed for a short period with other species (Neanderthals, and seemingly others), with whom we were genetically similar enough to interbreed and that the entire span of their existence was not much longer than ours. But ultiamtely we just don't have the data of a full census of the genetic history of most species to know what is typical in this regard, though we can make decent guesses based on extrapolated information. Snow (talk) 20:59, 7 July 2012 (UTC)

I read, I think in Nicolas Wade "Before the Dawn" a quote by some geneticist that the amount of genetic variation in humans, in any other animal would warrant a division into subspecies. Уга-уга12 (talk) 17:50, 7 July 2012 (UTC)

This image should give you a very good direct visual grasp of the difference in genetic diversity of humans compared to the other great apes: http://www.familyoriginstree.com/images/tree/tree_of_life.jpg Unfortunately I cannot find the original source. It would be appreciated if anyone familiar with the image can give the source. μηδείς (talk) 18:04, 7 July 2012 (UTC)

Too bad they didn't include any members of the genus Homo other than modern humans and Neanderthals. StuRat (talk) 20:38, 7 July 2012 (UTC)

That image is at least about five years old (it might be in Before the Dawn, actually) but I can't remember where I have seen it. In any case, Denisovan DNA info has only been available very recently and something just in the news said it is closer to Neanderthal than sapiens sapiens. μηδείς (talk) 21:51, 7 July 2012 (UTC)

Here's a more informative link to the human/great ape genetic diversity image which provides the source from 1999: http://www.icb.ufmg.br/lbem/aulas/grad/evol/humevol/extra/apediversity.html μηδείς (talk) 02:02, 8 July 2012 (UTC)

Still no other Homos (there are at least 7 more). StuRat (talk) 06:29, 8 July 2012 (UTC)

Here's a working link to: "To People the World, Start With 500" By Nicholas Wade NYT November 11, 1997 AS few as 500 or so people, trekking out of Africa 140,000 years ago, may have populated the rest of the globe.... μηδείς (talk) 02:07, 8 July 2012 (UTC)

I happen to think Wade's 140kya date is too old, and find the Toba catastrophe theory fits the linguistic and archeological evidence better. μηδείς (talk) 02:10, 8 July 2012 (UTC)

Sweet Potatoe vs kumara

I remember reading sometime ago, that the sweet potatoe is not native to New Zealand. I've read that the Maori brought a tuber vegetable with them which was called a kumara. Apparently, it was a sweet, relatively small vegetable that resembled a knobbly ginger root. Later, europeans introduced the sweet potatoe in the nineteenth century. The sweet potatoe is easier to cultivate, or something like that, so the Maori adopted the sweet potatoe as the kumara instead. Where can I find a source for this? Plasmic Physics (talk) 03:50, 7 July 2012 (UTC)

Sweet potato#New Zealand Snow (talk) 07:42, 7 July 2012 (UTC)

Reading around that section, it appears that kumara is simply the name for sweet potato in various languages and that the Maori only had a small variety which was replaced later by a bigger one after wider trade contact. Rmhermen (talk) 15:04, 7 July 2012 (UTC)

That was my take-away as well, though the wording could be clearer in the article. Snow (talk) 14:21, 8 July 2012 (UTC)

large hadron collider

what could make the particles to collide together during big bang as now it is collided by the LHC? — Preceding unsigned comment added by Haresiba (talk • contribs) 05:01, 7 July 2012 (UTC)

Just after the Big Bang the universe was very hot and very dense. So collisions or interactions between particles were both very energetic and very frequent. According to the LHC Brochure, when it is running at full power the collisions created by the LHC will have the same energy as typical collisions just 10^-12 seconds after the Big Bang, when the temperature of the universe was about 10¹⁶ degrees C. Gandalf61 (talk) 10:26, 7 July 2012 (UTC)

The LHC generates a bunch of nearly identical collisions in a single place, so that we can build a huge detector there and observe what happens. Conditions like that have never existed naturally. If you're just talking about random energetic collisions between particles, you don't have to go back to the big bang for that—cosmic ray collisions of higher energy than the LHC energy happen all the time in Earth's atmosphere. There's no good reason to say that the LHC "recreates conditions of the big bang". It's just hype. -- BenRG (talk) 13:01, 7 July 2012 (UTC)

Large Hadron Collider (Part 2)

They wanted to make it bigger, but God made a telling reach for his "Babel Stick".

Resolved

What is large - the hadrons or the collider? Roger (talk) 10:59, 7 July 2012 (UTC) The collider.--Gilderien Chat|List of good deeds 11:14, 7 July 2012 (UTC)

The collider itself, which has a length exceeding 27 kilometers (see map on right) and which weighs in at a healthy 38,000 tonnes. The particles are your run of the mill sort (protons composed of quarks). Snow (talk) 12:42, 7 July 2012 (UTC)

The collider is big but they are searching for "large hadrons" like the new Higgs-like boson at 133 times heavier than a proton. Rmhermen (talk) 14:59, 7 July 2012 (UTC)

The Higgs boson is believed to be an elementary particle; it is not a hadron. (A hadron is any one of a family of composite particles formed from two or more bound quarks.) The LHC facility has plans and facilities to accelerate protons and sometimes a bit of non-exotic hadronic matter (heavy ions like lead nuclei). TenOfAllTrades(talk) 15:19, 7 July 2012 (UTC)

An easy mistake to make, because some non-experts in popular treatment of the matter have implied as much, but in fact: Scientific American interview with Frank Wilczek. Also, as Ten points out, the Higgs boson is an an entirely different class of particle, being a much smaller excitation of the Higgs field than other elementary particles. Snow (talk) 18:09, 7 July 2012 (UTC)

My understanding was, the "large" qualifies the "hadrons." Any kid can build a hydrogen ion accelerator in his back yard and truthfully claim to be accelerating small hadrons, but only CERN has the resources to accelerate heavy nuclei like lead (Pb) to supermassive TeV states. And of course, it's also a particle collider, not just a heavy ion beam; every silicon shop from here to Hong Kong has an ion-beam epitaxy station; but only CERN has the energy to smash these heavy nuclei into other heavy nuclei. In fact, in senior year physics lab, I seem to recall building a proton cyclotron out of a tuna fish can and a neodymium magnet. That technology was Nobel-prize-worthy in 1939, but today it's a toy. It's one thing to excite a hadron and measure its presence - you do that every time you cook grapes in your microwave - but it's a totally different and much more difficult thing to collide a hadron with another one. Nimur (talk) 18:03, 7 July 2012 (UTC)

All true perhaps, but these hadrons are no larger than any other hadrons would be under the conditions of CERN project experiments. Also there's the fact that every physicist connected with CERN who I've ever heard refer to the installation and whose native language is English places the grammatical stress in the phrase in such a way as to suggest that "large" is an adjective modifying the combined compound noun phrase "hadron collider" as opposed to an adjective modifying the word hadron. Also, the acceleration of heavy ions take place in only a very small subset of the CERN projects and are not the main focus of research at the installation, which would make it an odd choice if the large were to refer to this work. Snow (talk) 18:28, 7 July 2012 (UTC)

The Superconducting Super Collider would have been a lot larger. Count Iblis (talk) 19:57, 7 July 2012 (UTC)

Shhhh, American physicists are still in mourning. Snow (talk) 21:56, 7 July 2012 (UTC)

• From the LHC website: "The LHC is exactly what its name suggests - a large collider of hadrons." LukeSurl ^{t c} 22:57, 7 July 2012 (UTC)

Well, I'd say that's case-closed. Snow (talk) 23:05, 7 July 2012 (UTC)

Gas phase 3rd order reaction rates for various M

For gas phase 3rd order reactions of the form A + B + M → AB + M, A + A + M → A₂ + M, and the like, there is a large body of published reaction rate data (constants to insert in arrhenius or modified arrhenious equation) for all sorts of atoms A and B, but for each sorts of A and B, only for a limitted range of M. The reaction rate is strongly dependent on what atom or molecule is M. How does one handle a situation where measured data is not available for a particular M?. Is there a way given reaction rate data for a few given types of M, you can roughly estimate rate data for a different M (say based on molecular weights or radius or something)? For example, for the reaction Br + Br + M > Br₂ + M, data has been published for M = N₂, Ne, Br, Br₂, O₂, etc, but not CO₂ or H₂O. Ratbone124.182.0.102 (talk) 14:40, 7 July 2012 (UTC)

Law of cause and effect

I was reading the iron chariots website which is a counter-apologetics website for atheists. Specifically here, where it addresses Kalām cosmological argument, and counters the premise that everything that begins to exist has a cause.

The counter argument is this, "Within quantum mechanics there seems to be real counter examples to the first premise of the argument. "Everything that begins to exist has a cause." For example, when Carbon-14 decays to Carbon-12 the radioactive decay is a perfectly random causeless event and thus though the Carbon-12 began to exist it wasn't caused to exist."

My understanding is that Carbon-14 decays due to the weak nuclear force, so couldn't it be said that the weak nuclear force is the cause?

Correct me if I'm wrong, but wouldn't a better example be the decay of pions? Even though they decay because of the weak nuclear force, it has two decay modes for both charged and neutral pions. But how it determines which to decay into is completely random, and thus is uncaused. Correct? ScienceApe (talk) 15:04, 7 July 2012 (UTC)

Carbon-14 decays to Nitrogen-14, not Carbon-12. Roger (talk) 15:16, 7 July 2012 (UTC)

I take this position: the deeper you dive into the semantics of a teleology debate - whether in the context of religion and philosophy, or in the more mundane examples of the application of the first principles of physics - the more ill-defined "cause" and "effect" become. I think this is basically what Feynman hoped to illustrate when he drew those ridiculous line-diagrams. Everyone else uses those diagrams as if they actually reveal some useful physical intuition - but Feynman never did that! The goofy diagrams are just examples to illustrate a philosophical point. If you draw time on the "x-axis," and you read from left to right, it looks like everything on the right half was caused by everything on the right side. But if you draw the energy on the x-axis, and time on the y-axis, ... suddenly everything at higher energy looks like it was caused by everything at lower energy. Your brain is (if you read English) conditioned to treat change in the +x direction as a "causal relationship," when in fact, you're the one making the assumption of cause/effect. The decaying particle makes no such assumption! The universe is doing its thing, exactly as it should, without worrying about what causes what. Unfortunately, most people don't get it - they're spending all this time trying to make nature fit into their tiny and ultimately limiting ideas about causality, drawing ridiculous squiggles to represent particle evolutions as if they mean anything... and that's probably why our fabulous article on Feynman diagrams doesn't actually cite Feynman, and why he's even got a whole chapter in his book about whether reading from right to left or from left to right is "correct"! Nimur (talk) 16:49, 7 July 2012 (UTC)

Not to mention, he has another entire chapter about how ridiculous it is to apply scientific methodology to settle disputes about medieval mysticism. Apologies to the now-deceased author for the link to a probable a copyright-violation - but at least hopefully it may spread some enlightenment. ... And spur some enthusiastic physics student to actually go track down where exactly in Feynman's text he actually drew that squiggle. Nimur (talk) 16:57, 7 July 2012 (UTC)

Uh... the point of those "ridiculous diagrams" was to simplify computations in quantum electrodynamics, not to make a philosophical point. And if Feynman didn't believe that the diagrams were physically meaningful, he certainly did a good job of faking it in QED. And if there's one thing about cause and effect that everyone can agree on, it's that causes precede effects. That's not the hard part. -- BenRG (talk) 00:05, 8 July 2012 (UTC)

It's funny that you should say that, because the exact quote I recall from Feynman was, "if (event A) is later than (event B), you're inclined to say the photon went from (here to there); and if (event B) is later than (event A), the photon went from (there to here); ...but it's a funny thing in relativity, it's very difficult to say for things that are nearly at the same time, which is ahead.... and this whole business of trying to decide which one is ahead, which one is emitting the photon, which one is absorbing the photon, is an irrelevancy." This is, incidentally, from QED Lecture # 3. Nimur (talk) 14:21, 8 July 2012 (UTC)

Roger's very reasonable objection aside, the point of the argument is that the time of the decay doesn't depend on anything that came before, and I don't think it's strengthened by considering a case where the products of the decay are also random. -- BenRG (talk) 00:29, 8 July 2012 (UTC)

I think we've run into a limitation of the word "cause" here. If you're dealing with quantum mechanics, you're dealing with probabilities. Let's consider the two-slit experiment, with a detector at each slit. What "causes" the photon to be detected at one slit instead of the other? Nothing. There was a finite probability that it would go through either slit, and it was detected where it was detected by random chance. In much the same way, nothing "causes" a radioactive atom or other unstable particle to decay; there's just a finite probability that it will occur at any instant, so when it does it is consistent with the laws of physics.

If you want to force a "cause" in there, you could say that the creation of the unstable particle was the cause of its decay. The laws of physics dictate that this particular particle is unstable, therefore it will decay at some point: that's a cause, albeit a fuzzy, hand-wavy one. -RunningOnBrains^(talk) 03:13, 8 July 2012 (UTC)

stupid and speculative optical media question

the fastest DVD-RW blanks today are 4x. The equivalent of 4x in CD speeds is 36x (both mean roughly 5.3 MByte/s). So, why are there no 36x CDRW blanks (12x is max), can't they just use the coating they use for DVD-RW blanks for CDRW? What am I missing? Уга-уга12 (talk) 17:29, 7 July 2012 (UTC)

High speeds mean more violent airflow around the disk, which causes the disk to flex and flutter. For reading, the CD-ROM#standard section (4th para) talks about increasing inaccuracy as speed increases. The need for accuracy is greater still when writing, an as CD-R#Speed notes, write speeds above 20x can be achieved only using a Constant linear velocity where the high speed is used only when writing to the inner portion of the disk (where the disk is stiffer). At higher speeds still (beyond the ambit of your question) the forces on the disk are such that compact Disc shattering is a concern. But lastly there's simply the issue of demand - if someone can burn a CD-ROM in 5 minutes, how much more are they willing to pay to do it in 2? - it seems like the CD-R and -RW makers have concluded that not enough people are willing to pay the necessary increment for them to make the investment in a factory to produce these wholesale (and they probably don't want the reputational damage they'd get when people with cheap burners can't reliably burn at those speeds anyway). -- Finlay McWalterჷTalk 19:08, 7 July 2012 (UTC)

Especially as the medium is moving (slowly) towards obsoletion (or at least a more limited role). Snow (talk) 19:46, 7 July 2012 (UTC)

Not sure that I agree with Finlay McWalter's answer. The CDRW is for CD writers of 'older' laser technology. Any CD manufacture must produce blanks to record within those limits. DVD writers have superior laser optics and tracking. So a DVD writer can write to both DVD and CD where as an 'old' CD writer can not write to a DVD. To mix the two up, would mean that customers would be buying CD's claiming to have a capacity that their writers can not achieve, thus leaving the manufacture liable to law suits for false advertising. --Aspro (talk) 19:56, 7 July 2012 (UTC)

thanks for all your answers. Уга-уга12 (talk) 10:27, 8 July 2012 (UTC)

Whitewashing coal

In the early days of coal mining the Davy lamp was used by miners for lighting. These lamps give out a paltry amount of light, so did anyone think of whitewashing the coal face to increase the illumination for the miner whilst he undercut the seam before blasting it away? --92.25.99.4 (talk) 19:28, 7 July 2012 (UTC)

That is ridiculous. Why would they whitewash the seam that they were hacking away? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:02, 7 July 2012 (UTC)

To see what they were doing my little friend.--92.25.99.4 (talk) 00:33, 8 July 2012 (UTC)

There are areas of coal they can't mine, either because it would destabilize the mine or because it's on property to which they don't have mining rights. Whitewashing that might make sense, depending on the cost of the paint and the flammability/toxicity of the fumes. There might also have been a problem with it drying in a cave. StuRat (talk) 20:22, 7 July 2012 (UTC)

Mine owners of the time wouldn’t care a dime about toxicity. It is very cheap. Flammability is an attribute that whitewash does not have. It works OK in damp cellars too (don't use whitewash distemper – it contains binders such as gums which can support some types of fungi and bacteria). It doesn’t 'dry.' It cures by absorbing CO2 -of which there is lots of underground and in cellars.--Aspro (talk) 20:42, 7 July 2012 (UTC)

That depends on how toxic it was. If it kills all the miners or they come running out of the mine clawing at their bleeding eyes, this will affect productivity. StuRat (talk) 06:21, 8 July 2012 (UTC)

Coal is brittle. One just hacks away it it with a pick axe. Back in those days they didn’t blast the coal but the rock blocking the way. Second. Back in those days, mine owners made the miners pay for their own explosives – he ruddy weren't going to pay for any white-wash. Thirdly. People get used to working in dark conditions. The feel from the pick axe handle tells them if they are hacking at coal or not. So, people may have thought about it but I shouldn't think it was ever put into practice until modern times.The last coal mine I was in (Copperfields up near Brum) had a lot of whitener in the access tunnels.--Aspro (talk) 20:18, 7 July 2012 (UTC)

Also, while I'm think about the safety aspect and mine-owners practices. The introduction of the Davy-lamp resulted in more deaths rather than less, because it encouraged working in seams that otherwise would have been considered to dangerous to contemplate. Something that the science books always forget to mention. --Aspro (talk) 20:51, 7 July 2012 (UTC)

Sorry You are talking thro the wrong orifice. Coal is definitely blasted with dynamite.--92.25.99.4 (talk) 00:36, 8 July 2012 (UTC)

Also, so a thin seam is darker than a thicker seam? Where do you get that from?--92.25.99.4 (talk) 00:41, 8 July 2012 (UTC)

"In the 1800s, coal was dug with a pick. Crouching or lying on his side, the collier carefully undercut the seam until a wedge or small powder charge brought the coal crashing down"[28]. Dynamite was invented 50 years or so after the Davy lamp. Alansplodge (talk) 01:04, 8 July 2012 (UTC)

The word "Collier" is actually a contraction of "coal hewer", who was the man with the pick who physically dug the coal in the mine. Coal was dug in this way until the 1980s at some pits in South and West Yorkshire. I used to have business dealings with a man who was the last coal hewer in Wakefield, who used his redundancy money to set up a brewery. --TammyMoet (talk) 08:11, 8 July 2012 (UTC)

The OED doesn't agree with you, Tammy: " Middle English colier , colyer , etc., < col, coal n.1, apparently after words from French in -ier suffix, q.v." --ColinFine (talk) 14:27, 8 July 2012 (UTC)

Someone better tell my ex-collier friends in Yorkshire that then! And the OED does say "apparently", so even they're not sure. --TammyMoet (talk) 14:59, 8 July 2012 (UTC)

"Coal hewer" sounds like a highly motivated folk etymology. μηδείς (talk) 18:10, 8 July 2012 (UTC)

So, did anyone think of using whitewash to give more effective illumination or not?--89.243.129.28 (talk) 15:05, 8 July 2012 (UTC)

July 8

On Growth and Form

I've heard a lot of good things about 'On Growth and Form', but the book is also nearly 100 years old. Is it still the best text on its topic, or has it been superseded by something more modern? 65.92.7.168 (talk) 00:55, 8 July 2012 (UTC)

It's a standard text like Helmholtz' On the Sensation of Tone which, due to its quality, remains a basic introductory text in its field, and hasn't been supeseded for what it covers, which is the basic geometry of bilogical form. I saw it on the shelves for undergraduate bio courses in the Ivy League schools in the 1990's. For a reader with general interests it's worth getting from the library and thumbing through, not spending money on with the expectation that you need to master it. Of course, developments in embryology and genetics since take the field from the level of what with D'Arcy Thompson is basically an art to one of the most complicated of sciences. The Shape of Life: Genes, Development, and the Evolution of Animal Form was a cutting edge popular work when it was published in 1996, dealing with the comparative genetic regulation of development such as the HOX genes. It's hardly up to date now, but it's still highly recommended. μηδείς (talk) 01:48, 8 July 2012 (UTC)

Electrides of elements with Z>173

Untriseptium and unsepttrium both state that unsepttrium is the heaviest possible neutral element.

But couldn't the elements beyond unsepttrium theoretically exist in a quasi-neutral state as their own electrides, such as unseptquadium(I) electride, [Usq⁺][e^-], unseptquadium(II) electride, [Usq²⁺][e^-]₂, and unseptpentium(II) electride, [Usp²⁺][e^-]₂, with the minimum oxidation state of the element in the electride being Z - 173? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:31, 8 July 2012 (UTC)

I won't pretend to know all the physics, but it seems to me that if heavier elements can not hold their own electrons in orbitals, there would be no reason that they could form an electride either. -RunningOnBrains^(talk) 03:07, 8 July 2012 (UTC)

*waits for explanation* Whoop whoop pull up ^{Bitching Betty | Averted crashes} 03:20, 8 July 2012 (UTC)

Well, the binding force for ionic bonds is the electromagnetic force, the same force that keeps electrons in their orbitals, so if an electron can not be bound in an orbital I don't see why it could be bound in a bond. Like I alluded to before though, I am certainly not an expert in nuclear (or quantum) physics.

The problem for the highly charged nucleus is not losing an electron from the outer shell, but that the field around the nucleus is so strong that the vacuum is split into positron and electrons with the resultant destruction of the innermost electron. Alternately I suppose you can think of the potential energy of the inner electron has become so negative it exceeds the rest mass of the electron. It would be like matter falling into a black-hole and crossing the event horizon. see Extended periodic table#End of the periodic table which needs an expert to improve it (not me). However sodium can spontaneously form an electride when it is put under pressure, where you can get black sodium, red sodium and transparent sodium, all electrides. It sounds a good topic for Whoop to write up. This phenomenon could do with more investigation and perhaps more elements can form electrides by themselves. Graeme Bartlett (talk) 07:19, 8 July 2012 (UTC)

Brain dead pregnant woman

What was the name of the pregnant woman who according to this webpage was declared brain dead at 24 weeks gestation but was kept on life support for another 9 weeks to allow the delivery of the baby? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 06:14, 8 July 2012 (UTC)

Christine Bolden?[29] Not sure it's the same person, but hard to say. That webpage is not a great source of physiologically accurate assumptions in the questions it asks. 71.212.249.178 (talk) 06:45, 8 July 2012 (UTC)

No, the woman in the article I mentioned did not give birth to twins, was kept on life support for twice as long, and was way back in 1988. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 06:58, 8 July 2012 (UTC)

We should list all articles about these incidents that we can find so that maybe we can find out which one that webpage was referring to. (There should already be a list of those somewhere on Wikipedia though...) Whoop whoop pull up ^{Bitching Betty | Averted crashes} 07:07, 8 July 2012 (UTC)

List of women who were declared brain dead while 24 weeks pregnant and were kept on artificial life support for nine more weeks in order to allow for delivery? Evanh2008 ^{(talk|contribs)} 07:16, 8 July 2012 (UTC)

WILL YOU PLEASE NOT MAKE FUN OF THIS QUESTION?!?!?!?!?!?!?!?! Whoop whoop pull up ^{Bitching Betty | Averted crashes} 07:47, 8 July 2012 (UTC)

Why not? Didn't you ask it for time-wasting fun, like most of your questions? Wickwack120.145.35.180 (talk) 12:33, 8 July 2012 (UTC)

I suspect you will not find the name online as all other references seem to derived from a single medical ethics paper (you can see the abstract here) and details of this nature tend to be kept confidential. But if your interests runs deep enough, you can try contacting the article's authors who may have already received consent to share said information Snow (talk) 07:06, 8 July 2012 (UTC)

• The case study is reported in PMID 3392814, available online in full here. The woman is not named, though. Looie496 (talk) 15:59, 8 July 2012 (UTC)

Patients are rarely named in the medical literature. Exceptions are people long gone (>100 years). OsmanRF34 (talk) 19:29, 8 July 2012 (UTC)

about wireless electricity transmission

is it possible to transmit electricity in a long distance? I am working in this project.It will be really beneficial. please give me some suggestions. — Preceding unsigned comment added by 1.38.16.23 (talk) 07:39, 8 July 2012 (UTC)

Yes, you can convert it to methane which can be transmitted in a pipeline. 71.212.249.178 (talk) 07:50, 8 July 2012 (UTC)

Yes, electricity can be transmitted without wires. See Microwave transmission#Microwave power transmission and Wireless energy transfer for details. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 07:51, 8 July 2012 (UTC)

There are four ways (and only 4 ways) to transmit electrical power from one place to another, without recourse to doing non electrical things like produce gas and pipe the gas:- 1) by wires (conduction), 2) by capacitive coupling, 3) by induction, and 4) by radio progagation. Sorry to dissapoint, but misguided but often mentioned efforts by Tesla, and wacky proposals for enormous satelite-to-earth systems notwithstanding, only conduction of wires is any good in practice, and it works really well. Electricity grids traverse netire continents. Capacitive coupling and induction come under the heading of "wireless energy transfer" and is inherently good for short distances only (distance <= diameter of devices). Capacitive coupling has had no significant commercial use as far as I know, but inductive transmission's main applications are swipe cards and RFID identification, and powering implanted medical devices from powered sources worn in clothing. Radio progation requires a transmit antenna, a recive antenna, and a space between the two, and as such is governed by the path loss equation, well known to radio engineers. The physics of the path loss equation is such that while radio waves can be detected at truly enormous distances (of galactic scale), radio propagation is really only practical for transmission of information, and not power. Typical path loss values are of the order of 10's of watts to kilowatts transmitted, and microwatts to picowatts received. If this is for a school project, I suggest you look up the 4 methods, get some undertanding why the physics means only transmission by wires is used in practice, then look at the various refinements of wire transmission, viz: High voltage AC, Extra High Voltage DC, and 3-phase transmission. Transmision of power by light is in some ways more promissing, as lenses and lasers offer much better directivity (ie are better focused into a beam) than do practical radio antennae, but even light transmission is also governed by the path loss equation, and will only be used for specail or niche applications. Keit124.178.37.91 (talk) 10:53, 8 July 2012 (UTC)

Transmission by wire is expressly disallowed by the OP. 84.209.89.214 (talk) 18:34, 8 July 2012 (UTC)

Practical transmission by light is used either for communication in optical fibers or in free space for switching tv channels. It is not useful for power transmission. Roger (talk) 14:15, 8 July 2012 (UTC)

Light is not currently used for power transmission (except is a few novel demonstrations, eg powering toy helicopters), but has much greater potential than does radio frequencies, for the reasons given above - this may be more appropriate to what the OP was looking for. Not only is much better beam focussing realisable in practice, but very high power lasers are practical. So in that sense, yes, it IS useful. Keit121.221.215.121 (talk) 14:50, 8 July 2012 (UTC)

Toy helicopters are only controlled, not powered, by light - they have LiPoly batteries on board. The controller works the same way as a tv remote. Roger (talk) 15:10, 8 July 2012 (UTC)

That was my first thought too, but then I remembered that this article in New Scientist covered a small helicopter in which power was beamed to it using a laser. Brammers (talk/c) 16:44, 8 July 2012 (UTC)

Not sure exactly what 'Keit' 121.221.215.121 was referring to there, but Microwaves have been used to power a helicopter, over a short distance and rather in-efficiently "In this experiment, the microwave energy itself was transferred with an efficiency of 51% over a distance of twenty-five feet, and then converted with an efficiency of 50% into DC power of 100 watts which was used to drive an electrical motor. ... A few months after this demonstration in microwave power transfer, personnel of the Raytheon Company conducted experiments with an electrically powered helicopter having rotor blade diameters of four and six feet. These helicopters exhibited an excess lifting capability sufficient to carry a lightweight receiving antenna and a close-spaced thermionic diode rectifier." Ref. Template:PDFlink (page 2). Not particularly practical. - 220 of ^Borg 16:53, 8 July 2012 (UTC)

The LaserMotive page may be of interest re. lasers for power transmission.--220 of ^Borg 18:07, 8 July 2012 (UTC)

The sun transfers energy over very long distances and we are able to transform that into electricity using solar cells so yes, wireless long distance transfer of electricity is possible. There are other methods as mentioned above.— Preceding unsigned comment added by ScienceApe (talk • contribs) 15:04, 8 July 2012 (UTC)

Unfortunately, conversion of light to electricity is highly inefficient, with additional inefficiencies added by conversion of the electricity into light at the source and losses during transmission. StuRat (talk) 17:33, 8 July 2012 (UTC)

(edit conflict)The OP was specifically asking about electricity transmission, but allowing 'energy' transmission this will pass. ;-) Certainly it is possible to transmit energy (electrical or other) using electro-magnetic radiation over long distances. Somewhat impractical for point-to-point use on a planetary surface though, which is what I think they are getting at. You need a fusion generator the size of a Star to begin with. - 220 of ^Borg 18:07, 8 July 2012 (UTC)

Flow of current by Electric arc is also possible. Air breaks down at about 30 kV/cm so the achievable distance may not be very long, but once established the arc behaves almost as a short circuit through which large power can be transmitted without wire. 84.209.89.214 (talk) 18:34, 8 July 2012 (UTC)

How to change the way the jet stream flows

The jet stream is flowing South of Britain causing bad weather, disrupting Wimbledon and it will likely cause problems for the London Olympics. So, how would one go about pushing the jet stream North? Count Iblis (talk) 15:32, 8 July 2012 (UTC)

At this point in the history of science and technology, and for the next couple of hundred years at least, the only method that has the faintest chance of success is prayer. Dominus Vobisdu (talk) 15:49, 8 July 2012 (UTC)

The only plausible way is by reducing global warming. And that isn't a joke answer: the details are very complex, but in a general way global warming should increase the meander in the jet stream, causing it to make more frequent southward excursions. Looie496 (talk) 15:52, 8 July 2012 (UTC)

This is highly speculative, and I'd like to see if there's any evidence of it. One of the consequences of increasing greenhouse gasses is that the equator-to-pole temperature gradient will decrease (this part is not up for debate, it's simple physics), leading to a weaker jet stream on average, and (here's the speculation on my part) a less meridionally amplified (fewer north-south meanders) Rossby wave pattern. So if my educated guessing is correct, global warming would lead to sunnier summertime weather for the British Isles. This is of course ignoring a huge amount of uncertainty in ENSO and other large-scale patterns. -RunningOnBrains^(talk) 18:48, 8 July 2012 (UTC)

And the best way to prevent weather from interfering with British sport events is to move those events to someplace else with better weather. Wimbledon, in particular, frequently had poor weather, long before global warming became a concern. StuRat (talk) 17:28, 8 July 2012 (UTC)

There is no way to change weather patterns reliably. Rossby waves (the waves in the jet stream flow) are dynamically chaotic, meaning that a small perturbation now will result in large changes in future behavior. That's why weather prediction is essentially useless after 7 days; you driving to work tomorrow could cause a perturbation that would result in a difference of 1000 km of the position of the jet stream two weeks from now. -RunningOnBrains^(talk) 18:39, 8 July 2012 (UTC)

How (in terms of physical motions and mechanics) does a slug foot walk?

In terms of physical motions and mechanics, how do slugs move about? I note 'succeeding waves of muscular contraction which move down the undersurface of the foot' (http://wiki.answers.com/Q/How_do_snails_move_around) - but how does this work, physically? How do 'succeeding waves of contraction' make the slug move forward? My four-year-old wants to know. (I would love to show him a video of a slug moving its foot upon glass, if this could help us to understand, but I see no such thing.)82.31.133.165 (talk) 19:47, 8 July 2012 (UTC)