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May 11

Photography treatment at The Guardian online.

The Guardian's online photographs look slightly washed out to me. I'm not sure I like the style but I'd like to experiment with reproducing it. What are they doing? Is it slightly-low-exposure-slightly-high-contrast? Is this going to be trendy? Hayttom 11:30, 11 May 2013 (UTC) — Preceding unsigned comment added by Hayttom (talk • contribs)

Can you give us a link to a specific example - the pictures on their main page right now don't look unusual to me. SteveBaker (talk) 14:03, 11 May 2013 (UTC)

It hasn't seemed so obvious since I asked the question but here is an example. I think I answered my own question above - it's low exposure with high contrast.

Resolved

.

Scuba + weight training?

Can we have an article on underwater weight training? I saw this guy if you google underwater weight training videos

Or

Www.underwaterbreathable.com

Just curious to know more!

Thanks, — Preceding unsigned comment added by 174.236.227.194 (talk) 11:40, 11 May 2013 (UTC)

You may find this explanation of the process of creating a new article helpful - please pay particular attention to the parts about notability and use of reliable sources. You don't seem to have asked a science question, so I'll stop there. -- Scray (talk) 12:08, 11 May 2013 (UTC)

Sustained weight training - or any other form effort - at depth is extremely dangerous as your increased respiration and heart rate will accelerate nitrogen on-gassing beyond the levels assumed by decompression tables and diving computers resulting in an increased risk of decompression sickness. Effort - even after a dive - is also to be avoided as it increases the risk associated with an undetected patent foramen ovale. In addition, breathing compressed air even at swimming pool depths places you at risk of a potentially fatal pulmonary barotrauma.

Perhaps there is something good to be said about underwater weight training, but I'd be surprised to find it in any sort of reliable source.78.245.228.100 (talk) 13:58, 11 May 2013 (UTC)

Oh? How about NAUI's textbook, Physics, Physiology, and Decompression Theory for the Commercial and Technical Diver (available through the NAUI bookstore)? During my training as a Nitrox Diver, we learned extensive details about physiology, including endurance and performance. Lots of things get really different when you aren't breathing atmospheric air at atmospheric pressure. Commercial and technical divers, especially those who dive deep and use exotic gases or trimix (helium/nitrogen/oxygen) need to know a lot about physiology so they can judge safety, endurance, and work capability. NAUI's technical diver text is probably as reliable a resource as you can find outside of a Navy manual. However, I do not believe the subject "underwater weightlifting" warrants an encyclopedia article. This sort of information, if properly referenced, could be covered in our articles about SCUBA, technical diving, diving physiology... but ultimately, if this sort of thing piques your interest, it requires a little bit more specialized treatment than can be reasonably covered in an encyclopedia article. That's why, for example, technical diving courses are a few hundred dive-hours into a reasonable SCUBA certification program. Nimur (talk) 17:20, 11 May 2013 (UTC)

I'm not sure if you're agreeing with me there or not. Are you suggesting that commonly used civilian and military dive tables or computers are calibrated for anything other than basically no-effort situations? Or that effort is strongly counter-indicated towards the end and after a dive due to the lung-shunting effect of the foram ovale? Or that pulmonary barotrauma isn't a significant risk from as little as 0.1bar overpressure?

You can check out for yourself the instructions to the MN90 tables (that's Marine Nationale - a navy manual) and the FFESSM the governing body of scuba diving in France have to say on the subject here De ce fait, il va de soi que dans le cadre de la plongée sportive ou de loisir, l’usage des tables MN90 fédérales est déconseillé pour toute activité sortant de son domaine d’utilisation, en particulier lorsqu’il s’agit d’effort physique important en immersion 78.245.228.100 (talk) 19:20, 11 May 2013 (UTC)

I think we're in agreement. I initially responded to dispel the claim that there are no reliable sources on the topic; there are many, though this arcana may be found in sources that are a bit too obscure for an encyclopedia article. Nimur (talk) 15:05, 13 May 2013 (UTC)

May 12

Why are there no terrestrial creatures that can emit electricity as a weapon?

Question as topic. I'm aware that this could be answered with 'because they haven't evolved yet', but I'm wondering if there's a reason why the only animals that can emit electricity from their bodies for attack/defence are all aquatic. Is there any reason that the same thing can't work in air? --Kurt Shaped Box (talk) 00:10, 12 May 2013 (UTC)

Mainly because when an electric eel tries to shock you the electricity has nice conductive water to flow through, but in air it has billions of ohms of air to get through. Potential divider has a nice diagram, if you imagine almost all of the volts being used up on the air, and an undetectable fraction being used across the much more conductive organism's body.--Gilderien Chat|List of good deeds 00:15, 12 May 2013 (UTC)

Perhaps the OP is refering to contact electrocution? Plasmic Physics (talk) 00:25, 12 May 2013 (UTC)

I was referring to either, really. --Kurt Shaped Box (talk) 01:10, 12 May 2013 (UTC)

Because water's a bloody good conductor and air isn't. Tonywalton ^Talk 01:16, 12 May 2013 (UTC)

I can imagine such a creature, say one that injects electrical contacts into the target. The question, then, is whether there is an evolutionary path that leads in that direction. There are plenty of land animals that already pierce the skin of their targets, such as snakes, so that part is already done. If there was some accidental electrical discharge, say as the result of mixing two components of a toxin which was injected, and that turned out to be useful in stunning the target, then evolution might tend to favor those with this feature. StuRat (talk) 02:29, 12 May 2013 (UTC)

• Because there is more than 10 orders of magnitude difference between the conductivity of air and fresh water, more than the difference of magnitude between 1/100th of a millimeter, and 100 kilometers. μηδείς (talk) 02:42, 12 May 2013 (UTC)

Could the pressure of water favor the production and use of electricity by creatures in the oceanic environment? It seems the problem is the production and deployment of electricity. Does the aquatic environment in some way favor this over the air/land environment? Bus stop (talk) 02:55, 12 May 2013 (UTC)

It's not pressure. It's dissolved electrolytes in the water that accounts for the difference. --Jayron32 03:29, 12 May 2013 (UTC)

Electroreception discusses active electrolocation and electrocommunication, both of which involve and animal emitting electrical signals to interact with the environment. These would not be very useful in a non-conductive medium (air), so they would not have evolved in terrestrial animals. I'm thinking that these abilities would be intermediate steps on the evolutionary path to using electricity as a weapon, and since they did not evolve in terrestrial animals, weapons-grade electricity producing organs didn't either.
This would not prevent aquatic animals with electrical shock capabilities from evolving into terrestrial creatures. The shocks might prove useful on land if physical contact could be made, but might cause burns to the shocker as well as the shockee.--Wikimedes (talk) 07:48, 12 May 2013 (UTC)

I can imagine an electric toad. Plasmic Physics (talk) 08:03, 12 May 2013 (UTC)

The star-nosed mole detects prey using electroreception. --Fama Clamosa (talk) 10:56, 12 May 2013 (UTC)

.

Apart from not having the good conductivity of water, there are other reasons why it's not going to work as a weapon for land animals. The most important is that the marine creatures that can issue electric shocks are basically fish (rays, eels) with no limbs. They have a simple muscular structure. The electric organs are comprised of modified muscle cells. When they shock prey or other creatures, they shock themselves. However, their simple limbless structure means nothing inconvenient to them happens physically, and, no doubt, their brains have adapted so they block out their own shocks and so "consciously" don't feel them. If a land animal, with its complex limbed anatomy with a vast array of muscles was to develop electric organs, the current though its own body would cause all sorts of inconvenient muscle contractions with legs jerking about. Note that an electric eel or ray is surrounded by a large amount of water stretching out in all directions. So whenever it makes a shock, the current in its own body is pretty consistant in where in its own body it flows. A land animal would have to cope with delivering shocks from various points on its own body into prey of all sorts of sizes and orientations. So the current in its own body would never flow twice in the same way, making it difficult for the nervous system to block out the pain.

Another reason is that the sea provides a large area of contact to prey - this means a large current can flow without needing an excessively high voltage. On land, only small areas of direct contact can occur, making it hard to deliver enough current.

Most land animals have fur or at least a reasonably thick skin. Dry skin, and especially fur, is a good electrical insulator. The only way to electrocute them with a reasonable voltage is through their feet or their mouth.

Wickwack 143.238.218.186 (talk) 11:27, 12 May 2013 (UTC)

Concerning your last statement: that is why I thought toad. Plasmic Physics (talk) 11:53, 12 May 2013 (UTC)

They're moist, and things tend to bite or grab them. Plasmic Physics (talk) 11:56, 12 May 2013 (UTC)

Probably not wise to electrocute something that's biting you. The shock will force their jaws to close. And if you kill them with their jaws locked closed, its definitely curtains for both. Wickwack 60.230.192.64 (talk) 13:22, 12 May 2013 (UTC)

Oh yea... Plasmic Physics (talk) 22:24, 12 May 2013 (UTC)

There's the possible example of the Mongolian Death Worm. Further research, however, is needed (and I have been indirectly sponsoring some, insamuch as I subscribe to an organisation which has mounted expeditions to search for specimens.) The poster formerly known as 87.81.230.195 212.95.237.92 (talk) 13:16, 13 May 2013 (UTC)

According to the Wiki article nobody has ever seen it. Further, it kills with electric discharge at a distance, which would defy the laws of physics, unless it carries a sizable Crocroft-Walton generator around with it. Sounds like you have been sinking money into finding the Mongolian equivalent of the abominable snowman, or the Australian Cougar, or perhaps the local bogeyman who sneaks in at night and steals naughty children. Wickwack 124.182.32.113 (talk) 14:13, 13 May 2013 (UTC)

Harbor seal rookeries in Maine & northeast

My spouse likes watching harbor seals. We are thinking of going to the northeast for our vacation in early June, and are wondering where are good places to go where this is a good chance of seeing harbor seals without having to go on some sort of a boat ride or tour. How far north do we need to go? Crypticfirefly (talk) 00:21, 12 May 2013 (UTC)

According to this PDF from NOAA, harbor seals are present seasonally as far south as Florida. So if your are in Key West you might have to travel north. :) --Fama Clamosa (talk) 12:09, 12 May 2013 (UTC)

My parents travelled to Maine a few summers back, which was the first time my mother saw seals in the US N.E. I'll see if I can find out where. μηδείς (talk) 18:38, 12 May 2013 (UTC)

Homo superior and human brain evolution

Most probably the 1911 novel The Hampdenshire Wonder first mentioned it — superior next generation of Homo sapiens — Homo superior. Three questions—

1. How are human species (mainly human brain) going to evolve in future?
2. What are the extra-ordinary/advanced/remarkable features these?
3. Will Homo sapiens evolve to Homo superior at all or it will be Homo inferior? (ref Human Brain size is shrinking?

Tito Dutta (contact) 00:54, 12 May 2013 (UTC)

"We don't answer requests for opinions, predictions or debate". Looks like a request for predictions to me... AndyTheGrump (talk) 00:57, 12 May 2013 (UTC)

Yes we shouldn't speculate but see Man After Man: An Anthropology of the Future for a book about it and the see also at the end of that article for various other more reasonable articles. Dmcq (talk) 01:04, 12 May 2013 (UTC)

Man After Man is a lot of fun, and so is Darwin's Radio, but if the OP expects an answer he should have asked this under the Entertainment desk. μηδείς (talk) 02:44, 12 May 2013 (UTC)

Astrophysics & Geography

1. Earth has an elliptical or exactly circular orbit?

2. If it is elliptical, then there must be apogee and perigee, and at the same time, we know that earth like planets can only exist in a narrow orbit space where the temperatures and energy received from the star are ideal for life (neither too hot, nor too cold) then why doesn't this shift in positions of earth pose a danger to global temperature and existence of life on earth?

3. 1 AU (Astronomical Unit)= Distance at which the Earth revolves around the Sun, has a constant value, how is this derived if the orbit is elliptical? An average is taken?

4. What is the reason for the rotation of earth? What force makes it revolve? — Preceding unsigned comment added by 117.200.253.88 (talk) 10:05, 12 May 2013 (UTC)

Your question sounds like homework to me. We are volunteers and it is not our policy to do your homework for you - but if you show evidence that you've tried but got stuck, we'll help you get unstuck. Have you thought what might be likely answers? What would be sensible? Having thought aboit it a bit, have you tried googling some likely phrases? How about looking up "Earth" on Wikipedia? Hint: if you put a kettle full of water on a stove top, does it boil instantly, or does it take some time while slowly getting hotter? The Earth's atmosphere and heated surface is a heck of lot bigger than a kettle of water. Wickwack 143.238.218.186 (talk) 11:01, 12 May 2013 (UTC)

(edit conflict)

1/2 Our page Earth's_orbit#Events_in_the_orbit states that the eccentricity of Earth's orbit is 0.0167, the perigee is 147 million km, and the apogee is 152 million km. Perigee occurs on 3rd July. The eccentricity is too little to make much difference to the climate; the differences in light/heat received due to the axis tilt is much more significant in causing Winter and Summer.

3 1 AU is the length the semi-major axis. See Ellipse#Elements_of_an_ellipse to see what this means; the Sun is at one of the focuses. (Strictly speaking the focus is the centre of mass of the Earth and Sun; this is inside the Sun).

4 The same as the Earth orbiting the Sun; the cloud of gas that the Solar System condensed from was rotating. See Formation_and_evolution_of_the_Solar_System

CS Miller (talk) 11:07, 12 May 2013 (UTC)

Note that the apparent rocking of the Earth relative to orbital axis is about + and - 23 degrees. The insolation (the energy per unit area) is proportional to the cosine of the incident angle to the surface, and this means the summer/winter energy variation from this cause, averaged over the whole [surface]{correction:} hemisphere, is about 11% {added to clarify} peak to peak. Incident energy is inversely proportional to the square of distance - this means the variation of insolation due to the Earth's orbital parameters is about (152/147)² i.e., about 6%. This is lower than the mean summer/winter variation, but it is NOT insignificant. What is important is that atmospheric and ocean currents spread the heat about, so that the total energy recieved over the whole Earth is important, as well as local insolation. Wickwack 143.238.218.186 (talk) 11:55, 12 May 2013 (UTC)

I haven't done the calculation, but the 11% figure seems too low to me. I guesstimate it to be at least 50%. Dauto (talk) 16:39, 12 May 2013 (UTC)

It is somewhat non-obvious what the 11% is actually comparing, and it might be helpful for Wickwack to specify where he got that figure from or how it was derived. (For the purposes of this post, I'm going to use 'summer' and 'winter' to refer to the times of year around the June and December solstices; 'spring' and 'autumn' will refer to the times of year around the March and September equinoxes.)

Consider a point on the Arctic circle (or anywhere north of it). On at least one day of the year (at the solstices), the location will receive a full day of sunlight or a full day of darkness. How should we score that? Is it a variation of 100%? At noon on the summer solstice, the sun still gets only 47 degrees above the horizon on the Arctic circle, giving only about 60% of the insolation we would see if it were overhead. Does that instead score as a variation of 60%?

You can also get some counterintuitive effects depending on your location. Consider, for instance, a point on the Earth's equator. At midsummer or midwinter, the Sun will make the same peak angle with the horizon, about 23 degrees from directly overhead—so the summer/winter variation in insolation due to axial inclination is actually zero. On the other hand, the Sun will be directly over head at the equinoxes, resulting in about 8% more insolation. So when considering variations in insolation due to axial tilt, is it more meaningful to report summer versus winter (0% difference), or annual minimum versus maximum (8% difference)?

Or should we integrate over the course of a full twenty-four hour period, to compare the min/max energy received per day, instead of just at noon? (Which then becomes more math than I feel like doing right now.) TenOfAllTrades(talk) 17:55, 12 May 2013 (UTC)

TenOfAllTrades has glipsed that an accurate calculation is actually quite complicated - that's one reason why I did not set out all all the math. Note only have I not mastered typing complicated equations in Wikipedia, I'm too lazy to spend the time doing it, and the length of it would turn most Ref Desk readers off, and most likely would not help the OP. However, some simple concepts are useful:-

• Clearly, as the heated upper surface of the Earth, sea, and the surrounding atmostphere supplies considerable thermal inertia, for the purposes of the OP's question, we should integrate the recieved energy over 24 hours. The recieved energy has 100% diurnal variation, but it is a sort of half-sine pulse with a period of zero ranging from zero to 24 hours depending on latitude and season. This makes it more complicated and introduces more error if you just take the noon peak.
• The received solar energy at the poles is indeed zero throughout winter. The variation in received solar energy summer/winter is obviously 100%. However, when quoting a mean variation over the whole hemisphere, the poles have little influence due to the small area involved. In fact, to be accurate, we need to progressivly discount by sine-weighting the variation at any latitude as we move further from the equator.
• When considering the equator, there is a maximum and a minimum twice a year. So, obviously there is a seasonal variation in received solar energy acording to cos(0) - cos(23^o), ie about 8% as TenOfAllTrades said. At the tropics the annual variation is similarly calculated as ~30%, which will sound familiar to those in the photovoltaic power generation industry.
• When calculating a hemisphere average, while the annual variation for the equator is obviously 8%, we need to take into account equatorial areas peak twice as often and also the peaks occur out of phase with with the peaks elsewhere. Due to atmospheric averaging, non-coincident peaks reduce the hemisphere variation.
• Don't forget that atmospheric and ocean currents spread the heat around considerably smoothing out temperatures, but have no direct effect on solar power generation.

On reviewing what I posted before, I see that my wording was a bit sloppy. I've made some corrections that should make the meaning of the 11% figure clear.

There is another interesting complication: The Earth, due to orbital parameters, is closer to the sun on [July 3 as CsMiller said - error; correction follows] January 3. This corresponds to Northern Hemisphere winter. If the Earth was a perfectly even geology, you would then expect Northern Hemisphere winters to be milder than southern hemisphere winters, and southern hemisphere summers to be [milder - eror] hotter. However, this is nicely balanced out by the trade winds and the Northern Hemisphere having a greater land area and less sea surface, affecting re-radiation back out to space. Every 23,000 years as the Earth's axis precesses, it actually reinforces variation instead of balancing it out - but then winds and perhaps ocean currents will change. Another reason why I don't have much faith in climate change modelling as it has been done to date - its another complexity that some ignore.

Wickwack 124.182.180.184 (talk) 01:30, 13 May 2013 (UTC)

July 3rd is the northern hemisphere winter? I could understand it being just a mistake if the rest of the explanation didn't perpetuate the notion, but since it does: am I missing something? I live in North America, which I assume is in the northern hemisphere, and I'm pretty sure that July 3rd is summer here. So I would expect that southern hemisphere winters would be milder, and... as far as I know, they are? If you compare, say, Rio Gallegos to Sept-Iles, the average mean daily temperature from June to September in Rio is 2.73 Celsius, while from December to March in Sept-Iles the same is -11.78 Celsius - clearly the winter is milder in Rio, even though it is actually further south (51°38′S) than Sept-Iles is north (50°13′N). (Those are just two points I picked randomly by looking at google maps trying to find cities approximately equidistant from the equator with WP pages with climate information). Interestingly both cities have very very close average daily means for their respective summer temperatures. So, uh, I guess my point is that I know nothing about that stuff but I think there's an error in your explanation and also I'm not sure about the point it makes even if the error was corrected. 64.201.173.145 (talk) 16:00, 13 May 2013 (UTC)

I should have written "The Earth ... is closer to the Sun on January 3 (Perigee; more correctly perihelion - note CsMiller quoted the date for aphelion by mistake). This corresponds to Northern Hemisphere winter." The rest of it then makes sense, or should do. Good cop, 64.201.173.135! Having implied two other people recently did not check their facts, I went ahead with combining repeating CsMiller's error, which I didn't spot, with going on memory of this aspect of climate, and not checking my self. One should always be carefull when comparing the local climate of locations of similar latitude. Rio Gallego virtualy surrounded by sea on all sides - this generally makes for a milder climate when ocean currents are not an influence. Sept-Illes in Canada is comparitively land-locked rendered cooler by other factors. One can easily find coastal cities at the same latitude in the same hemisphere that have different climate. Wickwack 121.221.30.176 (talk) 01:37, 14 May 2013 (UTC)

I'm still very suspicious of the 11% figure. Dauto (talk) 18:15, 13 May 2013 (UTC)

Perhaps you could explain the basis of your suspicion, Dauto. The figure clearly can't be anywhere near the 50% figure you estimated. Do you have a new estimate after reading my post? Wickwack 121.221.30.176 (talk) 01:44, 14 May 2013 (UTC)

July 3rd is actually the Earth's aphelium, when the sun is in the farthest point from the Earth, making northern hemisphere's summer milder. The Earth's perihelium happens in January making northern hemisphere's winter milder. Dauto (talk) 18:15, 13 May 2013 (UTC)

May 13

Other than dogs, what animals mainly perspirate by drooling?

--朝鲜的轮子 (talk) 01:56, 13 May 2013 (UTC)

Dogs don't really perspire by "drooling", they use panting to get rid of excess heat, the drool helps with the efficiency of the panting. Panting is also used for thermoregulation by pigs, cats and many birds. Vespine (talk) 02:56, 13 May 2013 (UTC)

I thought there's a theory about human's running. It says humans are "born to run long distances". People sweat and it helps you get rid of excess heat "in the long run". On the other hand, many other animals are only capable of sprinting. -- Toytoy (talk) 03:15, 13 May 2013 (UTC)

There's something to be said for that; famously in the Man versus Horse Marathon sometimes the man wins. That is, while horses are better, on average, at running a marathon-like distance, it isn't such an overwhelming advantage that some people can't outrace some horses over long distances. Quite notably, as the article Perspiration notes, while many mammals sweat, humans and horses are among the few that do so as an efficient means of thermoregulation; and notably horses are somewhat better long distance runners than humans. --Jayron32 03:31, 13 May 2013 (UTC)

Competitors in the 2006 Man versus Horse Marathon

This is unfair!

That poor horse has a man on his back.

To be fair, the man in front must carry a horse on his back! -- Toytoy (talk) 04:07, 13 May 2013 (UTC)

He already has a horse at his back... :-) Double sharp (talk) 13:41, 13 May 2013 (UTC)

22 miles is rather too short for an advantage for a man against a horse, it should really be over something like twice that distance and wild horses have been caught on foot just by running after them, it can be dangerous for the horse though. However for smaller animals like kudu persistence hunting is used by bushmen in a distance like 20 miles to tire down and kill prey, see [[1]]. Dmcq (talk) 09:18, 13 May 2013 (UTC)

(Speaking of horses...) I know very little about horse perspiration (that's not an article!), but I have rather distinct memories of horses I've been acquainted with being exceptionally drool-y (and that's not a word!) on hot summer days. My best guess at the time was that it was something like dogs' version of thermoregulation, minus the panting. I haven't been able to come up with a better explanation yet. Evanh2008 ^{(talk|contribs)} 06:06, 13 May 2013 (UTC)

Don't horses show froth or foam on their flanks when they've been ridden hard? I know hardly anything about horses, but remember reading it in different places. Alansplodge (talk) 17:24, 13 May 2013 (UTC)

Now that you mention it, that does sound like something I've heard in the past. The odd thing about this is that my most vivid memory of it involves an entire pasture of horses. They all would have been ridden fairly regularly, but I'm certain not all of them had been ridden that day or even that week. Evanh2008 ^{(talk|contribs)} 17:32, 13 May 2013 (UTC)

Frothing on the body depends on the action of friction on the sweat. See discussion. μηδείς (talk) 20:49, 13 May 2013 (UTC)

This was definitely originating from the mouth, rather than the body. Evanh2008 ^{(talk|contribs)} 00:35, 14 May 2013 (UTC)

Is it true that dogs have very few sweat glands except on their heads?--朝鲜的轮子 (talk) 02:57, 14 May 2013 (UTC)

Mammals like cats, dogs and pigs, rely on panting or other means for thermal regulation and have sweat glands only in foot pads and snout. Evanh2008 ^{(talk|contribs)} 03:09, 14 May 2013 (UTC)

Clam meat

Clams are usually sold by weight. Let's say all clams are sold at the same price by weight, and there are large, medium and small clams for sale. What kind of clam would you buy in order to get the maximum amount of edible clam meat? -- Toytoy (talk) 03:11, 13 May 2013 (UTC)

Depends on what you want to use them for. The larger the clam, the tougher the meat. Small clams are good raw or steamed on the half-shell. Larger clams should be used in chowder. What you want to do with them should be of greater concern for you than simply the total amount of meat. Think of it this way: filet mignon costs different than brisket, but you don't use them for the same thing. I'd never make pastrami out of filet mignon, and brisket is far too tough for making grilling steaks out of. Same with the clams. Regardless of which gets you the best "bargain", it isn't a bargain if the quality is not what you want. --Jayron32 03:14, 13 May 2013 (UTC)

To answer the question, I'd go for the larger clams to get most edible meat per weight. Here's my reasoning and assumptions: the shell thickness doesn't vary much, but total weight does. That is, a 4 oz clam may have a thicker shell than a 2 oz clam, but probably not twice as thick. The larger clams should have relatively less of their weight taken up by shell, compared to smaller clams. This is also assuming that we are talking about different size classes of the same species. Note that clam can mean many different species in USA English. SemanticMantis (talk) 14:22, 13 May 2013 (UTC)

A Boy and His Atom

This video is a stop-motion film made by IBM engineers using carbon monoxide molecules (the video describes them as "atoms," which I guess they technically are). Around the molecules, you can see something like a double image, almost a blurry, ripple-like duplicate of the molecules, only it may be many times double. Given the spacing of the atoms and the number of duplicates, it's hard to tell the exact number. My theory so far is that this is an optic effect (for lack of a better term), likely caused by mechanical oscillations in the microscope itself, as the imaging device vibrates, causing something like you may see when someone with an unsteady hand snaps a picture with a digital camera. What I can't figure out is why the molecules themselves aren't distorted in the picture (as you would see with a typical double exposure). But if that is the explanation, I can't figure out why you wouldn't see an identical effect with other pictures of small objects taken with electron microscopes. Any thoughts? Evanh2008 ^{(talk|contribs)} 05:59, 13 May 2013 (UTC)

This question is specifically answered in text and in video form at IBM's website: Made With Atoms. Nimur (talk) 06:18, 13 May 2013 (UTC)

And that's how the ref desk is supposed to work! Thanks, Nimur! :) Evanh2008 ^{(talk|contribs)} 06:23, 13 May 2013 (UTC)

Peroxodisulphate

calculate the volume of 0.01M peroxodisulphate ions required to oxidize 25cm³ of iron(Π) ions to ironΙΙΙ ions.iron(ΙΙ) ions were obtained by dissolving 1.12g of iron in dilute sulphuric acid — Preceding unsigned comment added by Nabwire (talk • contribs) 12:32, 13 May 2013 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. Red Act (talk) 13:32, 13 May 2013 (UTC)

Zero point energy and the volume of the universe.

Why doesn't the zero-point energy density of the vacuum change with changes in the volume of the universe? And related to that, why doesn't the large constant zero-point energy density of the vacuum cause a large cosmological constant? Is it allowed to postulate / hypothesize on this topic on the reference desk, or is there a separate science forum / talk page for that? Robert van der Hoff (talk) 06:49, 7 May 2013 (UTC)

Robert, the idea is that a header is a **short** (up to about 7 words) pointer to what the question is about, the meat of which then appears below the header. -- Jack of Oz [Talk] 07:32, 7 May 2013 (UTC)

(I made a more concise title and transferred the L-O-N-G title into the message body). SteveBaker (talk) 12:59, 7 May 2013 (UTC)

• We don't encourage using the reference desk simply to initiate discussion - especially when it's to discuss some idea that you had. However, there is a reasonable question here that we can possibly answer. SteveBaker (talk) 13:01, 7 May 2013 (UTC)

You hit the nail right on the head. That is indeed a very deep mystery that is yet to be satisfactorily answer by modern physics. Naive calculations show that the cosmologic is about 120 orders of magnitude off (If memory serves). Supersymmetry improves that to "only" 60 orders of magnitude. Dauto (talk) 22:28, 7 May 2013 (UTC)

And did you read the Zero-point energy article? where energy per particle is ½hν, not necessarily a very high density by cosmological standards. And this article also mentions renormalization to deal with the possibility of the lowest energy level of fields also containing energy. Graeme Bartlett (talk) 08:05, 8 May 2013 (UTC)

It's not ½hν per particle. It's ½hν per vibration mode of each bosonic field which strictly speaking is infinite hence the need for renormalization. Dauto (talk) 17:18, 8 May 2013 (UTC)

I read the article, and also the one about quantum foam, and the relevant sections from the book 'the fabric of the cosmos'. What I don't understand is how it relates to the universe we know. What are the properties or conditions of the quantum foam that triggered the Big Bang?Robert van der Hoff (talk) 13:38, 13 May 2013 (UTC)

Isn't this question listed in List of unsolved problems in physics? RJFJR (talk) 16:15, 13 May 2013 (UTC)

Correct, but there seems to be little movement in trying to solve it. I still hope that somebody will try to answer my question.Robert van der Hoff (talk) 11:29, 14 May 2013 (UTC)

Carbohydrate jacket potato overdose?

I was told earlier (during lunch funny enough) that it's possible to overdose on jacket potato...I'm aware you can overdose on vitamins, but there aren't any high vitamin values in jacket potatoes are there? The only decent Google references to this i could find point to someone named "Harvey" managing to "carb overdose" on 3 jacket potatoes. So really my question is how safe would it be to eat a jacket potato on a daily basis? Thanks ツ Jenova20 ^(email) 14:53, 13 May 2013 (UTC)

Think this is a miss use of semantics. Overdose usually in the vernacular means: taking too much of a drug. [2] Too much carbohydrate (at the expense of protein) will only leave you with stunted growth and that is a dietary thing. One just requires a balanced diet. If you do wrestling, then you could have a huge intake of calories and still be healthy. Sumo's eat amassing quantities of rice but burn it of in training.--Aspro (talk) 15:20, 13 May 2013 (UTC)

That's jacket potato, in case anyone else is unfamiliar with the term. Otherwise I agree with Aspro, this is a very informal usage (or just incorrect, e.g. overdose). Compare to "He overdosed on Breaking Bad, watching 50 episodes in two days!" SemanticMantis (talk) 15:36, 13 May 2013 (UTC)

I'm already stumped on this one... ツ Jenova20 ^(email) 15:45, 13 May 2013 (UTC)

A diet of whole milk and potatoes would supply almost all of the food elements necessary for the maintenance of the human body. Count Iblis (talk) 15:52, 13 May 2013 (UTC)

That's certainly interesting. So there's no issues of any overdose, like with a potassium overdose from eating hundreds of bananas? Thanks ツ Jenova20 ^(email) 16:02, 13 May 2013 (UTC)

. An organization whose sole raison d'être is to sell more potatoes is not where I would go for information on whether I should eat more potatoes. --Jayron32 16:17, 13 May 2013 (UTC)

I eat about 1 kg of potatoes a day, I doubt most people could eat this much. While 1 kg of potatoes contains a lot of nutrients, I still need to eat a lot of vegetables, fruits etc. to get all the nutrients I need. So, overdosing on potatoes isn't really feasible as our stomachs are too small. Perhaps big animals that eat foods low in nutrients like e.g. cows or elephants could overdose on potatoes. Count Iblis (talk) 16:31, 13 May 2013 (UTC)

• See hyperglycemia, diabetes, ketoacidosis, and death. μηδείς (talk) 17:48, 13 May 2013 (UTC)

Diabetes? Is there really much sugar in potato? I know it's starchy but i'm not really really technical with this stuff. Thanks ツ Jenova20 ^(email) 19:48, 13 May 2013 (UTC)

Starch is sugar, essentially. All carbohydrates are simply chains of sugar molecules of varying length, from one (Glucose and fructose) to two (sucrose and maltose) to shortish chains starch to long, complicatedly branching chains (cellulose and dietary fiber). The key is Glycemic index which tells how fast the digestion of various carbohydrates releases glucose into the blood stream. Foods with low glycemic index slowly release glucose, so you don't get high glucose concentrations, which is good, diabetically speaking. Foods which are high in glycemic index cause large spikes in blood glucose levels, which is bad diabetically speaking. Baked russet potatoes are among the worst foods in terms of glycemic index: 111, per this table published by Harvard Medical School, which makes it worse than pure glucose. Even boiled or mashed potatoes are pretty high, ranking in the 80s. It's hard to do worse, in terms of picking foods which are bad for blood glucose, than potatoes. --Jayron32 20:47, 13 May 2013 (UTC)

Starch is actually a chain of pure sugar with some water extracted. It converts entirely to sugar, starting even in the mouth with the action of pepsin in the saliva. μηδείς (talk) 20:45, 13 May 2013 (UTC)

Would it be possible to get an excessive amount of solanine or related compounds from eating potato skins? RJFJR (talk) 21:00, 13 May 2013 (UTC)

This article says that most commercial varieties of potato have between 2-13 mg/100 g of solanine in them. The TDLo for humans is 2.8 mg/kg: www.look chem.com/SOLANINE/. So, an 80 kg person would have to eat 224 mg of solanine to be toxic, that would mean eating 1.72 kg of potatoes, assuming the 13 mg/100 g at the high end of solanine concentration. The average Russet potato (one of the larger varieties) is 299 g: www.food facts.com/NutritionFacts/Fruits-Nuts-Seeds-Vegetables/Potatoes-Russet-Raw--Large-Potato-w-Skin-/21020. That would mean you'd need to eat 5.75 whole russet potatoes in a sitting to get toxic effects from solanine, assuming the worst case scenario. Unlikely, but not impossible. (refs hit spam filter. Take out spaces to get them) --Jayron32 21:16, 13 May 2013 (UTC)

You might try our article on solanine, just not the green potatoes. μηδείς (talk) 22:03, 13 May 2013 (UTC)

All potatoes contain some solanine, the data above is for average, standard store-bought potatoes of good eating quality. Green potatoes would, of course, contain even more solanine that what is noted above. --Jayron32 22:09, 13 May 2013 (UTC)

Hmmm, I'm not far below this limit with my 59 kg bodyweight and 1 kg of potatoes per day. Count Iblis (talk) 22:42, 13 May 2013 (UTC)

Some naturopaths claim that potatoes aggravate arthritis - a disease of elderly people. I've never believed it myself, as I am elderly, arthritis free, and eat a lot of potatoes, which contain vitamin C, but how old is Count Iblis? Wickwack 121.221.30.176 (talk) 01:55, 14 May 2013 (UTC)

Hot Jupiters

With Hot Jupiters, how is their mass, density, and composition determined? Bubba73 ^{You talkin' to me?} 16:25, 13 May 2013 (UTC)

AFAIK, you need planets that you can detect both via the Doppler method and the Transit method. In that case, you know that the orbital plane of the planet is (very nearly) aligned with a line from the star to the observer, and hence that all of the radial velocity difference visible in the doppler shift. Then you have the ratio of masses and the orbital period, and you can solve for mass. The transit observation shows you how much of the star is covered by the planet during transit, and hence the diameter of the planet. From that you get the volumen, and with the mass (and math ;-) the density. I don't think you can completely determine the composition, but the density gives you a good initial guess, and in the best cases, you can get spectroscopic data from the atmosphere during transits. --Stephan Schulz (talk) 16:38, 13 May 2013 (UTC)

OK, I see how you get the size, but how do you get the mass? Bubba73 ^{You talkin' to me?} 16:46, 13 May 2013 (UTC)

From the radial velocity changes, you get the relative ratio of the masses (the heavier the planet, the more it pulls the star around). You also know the orbital period (from the timing of transitions or doppler shifts). That gives you two equations for two variables. --Stephan Schulz (talk) 16:50, 13 May 2013 (UTC)

OK, the ratio of the mass of the planet and the star.

Resolved

Bubba73 ^{You talkin' to me?} 17:04, 13 May 2013 (UTC)

galactic plane all the same?

How closely aligned to our solar system's are the orbital planes of other planetary systems on average? μηδείς (talk) 17:45, 13 May 2013 (UTC)

They are not aligned at all. Ruslik_Zero 19:14, 13 May 2013 (UTC)

Ugh? You didn't give any references, so that's really no answer at all. [3] suggests that all stars, planets and star polars start up the same way. But the op is asking for an average or better description, like a bell curve as it applies to OUR solar system in OUR galaxy to other planetary systems in OUR galaxy --Aspro (talk) 19:44, 13 May 2013 (UTC)

I'm sorry, but I cannot find anything about the orbital planes of planetary systems in the linked article (that may be my failure). As far as I can tell, it only talks about the orbits of stars in the galactic plane. --Stephan Schulz (talk) 21:11, 13 May 2013 (UTC)

She didn't specify it was confined to our galaxy. -- Jack of Oz ^[Talk] 20:19, 13 May 2013 (UTC)

Quote the OP : "How closely aligned to our solar system's are the orbital planes of other planetary systems on average?"

What is there in that to suggest other galactical bodies other than our own? Use a modicum of commons sense.--Aspro (talk) 20:33, 13 May 2013 (UTC)

What is there in that to suggest other galaxies are excluded? Keep your remarks civil, please. -- Jack of Oz ^[Talk] 20:41, 13 May 2013 (UTC)

I didn't think it was necessary to mention the galactic plane twice, I usually assume common sense on behalf of the regulars here. Also, how many planetary systems in other galaxies do we have information on? Also, is it not obvious other galaxies all spin at random angles to ours? I am basically curious if there's any information; average, anecdotal, from a study, theoretical, whatever; that suggests there's a better than chance alignment of planetary planes in the galaxy. μηδείς (talk) 20:42, 13 May 2013 (UTC)

At least Kepler data is interpreted with the assumption that orbital planes of other stars are randomly aligned. Kepler is also looking "up", so this assumption has also been build into the mission (if planetary orbits were aligned with ours, Kepler would miss them all). --Stephan Schulz (talk) 21:19, 13 May 2013 (UTC)

Well, that article shows a field that looks pretty close to the galactic plane near Cygnus, so it's a matter of degree - it's certainly not pointed straight out to deep space. Wnt (talk) 16:57, 14 May 2013 (UTC)

Damned reference system confusion! I was talking about "up" from a solar system perspective, where "up" from the ecliptic is the side where Earth North Pole is, not "up" in a galactic reference system. --Stephan Schulz (talk) 19:27, 14 May 2013 (UTC)

Transits of planets close to stars in our galaxy are barely detectable. Yet, if you are insatiable (and I can think of better terms) you can search for them here. [[4]] For other planets in other galaxies far, far, aware -forget it -the orders of magnitudes are not yet within our realms detectability – Jesus (etc.,) -we can’t see planets on the other side of our own universes let alone other galaxies. Quote: ”Also, is it not obvious other galaxies all spin at random angles to ours?” Have you hear off “big bang" and space telescopes show everything flowing – blooming off from the centre?” Ballooning other analogies? Hubble & other images show it. Perhaps not obvious (to you) but it is very evident evident. Its not planetary planes but galactic planes. Quote: “other galaxies all spin at random angles to ours” they did not! Computer modelling has shown that the universe ended up in its present state according to to the physics that we now understand.Aspro (talk) 22:28, 13 May 2013 (UTC)

Your comment is very confusing, Aspro, and you seem to be conflating the words galaxy and universe, perhaps because galaxies used to be called island universes. In any case, I am talking about objects like the Milky Way and Andromeda when I speak of galaxies in general. It is quite obvious from both catalog and deep field images that their spin is random in relation to the spin of our galaxy. In any case, my question is only about the various planetary systems in our galaxy alone. μηδείς (talk) 23:56, 13 May 2013 (UTC)

Sorry, but nothing is "flying off from the centre", unless (maybe) you think in more than the customary dimensions. The metric expansion of space has no center. And the Hubble Deep Field and Galaxy Zoo do not seem to find much bias in galaxy orientation in the universe at large. I'm also confused by your plural use of "universes", and the idea of "the other side" of our universe(s). But yes, as far as I know, we have not yet detected any planets in another galaxy. We can resolve individual stars in nearby galaxies, so in principle it could be possible to use the transit method. --Stephan Schulz (talk) 22:54, 13 May 2013 (UTC)

When I was a child, the classroom dictionary said that "the universe" and "the milky way galaxy" were synonyms. Since that dictionary was printed, astronomers determined that there were other galaxies in the "universe." Edison (talk) 02:01, 14 May 2013 (UTC)

Are you the Edison and have invented a longevity machine, or was your school using really outdated books? The topic was settled late, but it was settled by 1930 or so. --Stephan Schulz (talk) 06:30, 14 May 2013 (UTC)

I was a child a long time ago, the classroom dictionary was an old one, and dictionary writers apparently took a surprisingly long time to stop saying that the Milky way galaxy equalled "the universe." Edison (talk) 16:05, 14 May 2013 (UTC)

Extragalactic planets. Dragons flight (talk) 23:23, 13 May 2013 (UTC)

And specifically: An extra-galactic planet has been detected in Andromeda, lovingly named OGLE-2005-BLG-390Lb. They used gravitational microlensing techniques to find it. SteveBaker (talk) 19:58, 14 May 2013 (UTC)

That page says it's ~20,000 ly away and in the Scorpius constellation, while Andromeda is 2.5 million ly away and in the Andromeda constellation. --Sean 20:58, 14 May 2013 (UTC)

It seems doubtful that any planets could be detected by wobble or by transit, the only means of analysis currently available, if they were not in our own galaxy. So the question must apply to planets in the Milky Way galaxy. The transit method only reveals a planet if its orientation is has an axis such that it passes between us and its star. I'm not so sure about the wobble method. Edison (talk) 01:54, 14 May 2013 (UTC)

I actually studied at Cornell as an undergrad because I was a huge fan of Carl Sagan, although I never did meet him. So I can speculate on my own. The extragalactic article mentions an unrepeatable observation, an unconfirmed one, and a rogue planet of assumed extraterrestrial origin, but no information on intragalactic (or intergalactic) systems. I can draw surmises from the Kepler article, but they are surmises. I do believe we have some professional or at least credentialed astronomers here, so I hope there will be more comment. μηδείς (talk) 03:57, 14 May 2013 (UTC)

I want to have new discussion about this , has solar system sidereal rotation?--Akbarmohammadzade (talk) 05:47, 14 May 2013 (UTC)

See your question "Has solar system sidereal rotation?" below. Wickwack 60.230.230.117 (talk) 06:38, 14 May 2013 (UTC)

In the astrophysics literature, it is standard to assume that the orbital planes of other stars are completely random. Every statistic you see in the news relating to exoplanet frequencies (i.e. "there are 2 billion Earth-like planets in the habitable zones of Sun-like stars in the Milky Way") is going to have that assumption built in. That's how we calculate the geometric transit probability of detected planets, and from there, work backwards to deduce how many of that type of planet there must be.

As of now, there's no way to test the assumption of random orientation. If a planet transits its star, we can deduce its inclination with respect to the plane of the sky, but this will always be close to 90 degrees (or else the planet wouldn't transit). To determine its 3D orientation, one more angle is required, and that's the direction of the orbital axis in the sky plane. There's no way to measure this angle because for almost every star, the star itself is a point of light, the planet is invisible, and the star does not move enough due to the planet to be detectable by astrometry.

That said, it would be quite surprising if orbital planes weren't randomly oriented. The molecular gas clouds that stellar systems originate from are expected to have tiny rotation rates determined by chance and internal dynamics, not the galaxy (see [5]). When they collapse, whatever direction the cloud's net angular momentum happens to be pointing in defines the stellar system's orbital plane. Also, we have evidence that the orbital planes of binary stars are randomly oriented, and the formation process of binary stars is roughly analogous to that of planets: [6]. --Bowlhover (talk) 08:13, 14 May 2013 (UTC)

The plane of rotation is defined by the net angular momentum. Physicists believe, rather religiously, actually, that conservation of angular momentum is one of the most fundamental properties of the universe - and is never violated. If many different objects - planetary or stellar systems - have the same plane of rotation, then they have aligned angular momentum - which doesn't cancel out if you look at the ensemble. The whole group therefore has angular momentum, and always had angular momentum. Consider two possible consequences of that hypothetical observation, spanning all cases:

• This is a local observation. Suppose we broaden our search and find that more distant systems do not align with the local systems. Elsewhere in the universe, if we looked on a bigger scale, the angular momentum is oriented differently, and does cancel out. Therefore, the universe is strongly inhomogeneous at very large length scales. Some parts "birthed" into existence carrying different values of built-in momentum.
• This is a global observation. Suppose we hypothetically observe very far into the universe; and everywhere we look, in the entire universe, all the planes of rotation line up. The universe has therefore a net angular momentum; this defines an axis of rotation: and therefore, the universe has a preferred direction. The universe is strongly anisotropic at very large length scales. The universe "birthed" into existence already spinning along a particular axis.

Now, as observationalist physicists, we can't seriously conclude either case to be true, but we can quantitatively bound how probable these cases can be, based on our observations of apparently random orientations of stellar systems. We can say that for case one, if such inhomogeneity exists, it must occur on length scales larger than L... where L can be specified based on our observation. Or, we can say that for case two, if such anisotropy exists, its net "strength" must be weaker than S based on our counterobservations at small length scales.

I have frequently stated that the only actual questions left in cosmology boil down to these two: how anisotropic is the universe? How inhomogeneous is the universe? And we can say to both, "less than some maximum, and more than some minimum, based on what we observe..." Either way, we can't make a very strong claim, and our bounds are so very broad as to be almost useless. This is because our observations are very sparse, and are limited by our technological capability to study distant stellar systems from here at Earth. But, we've quantitfied the limits of our knowledge!

Finally we're thinking and talking like real actual cosmologists, rather than pop-pulp-science-fiction-writers! Nimur (talk) 14:22, 14 May 2013 (UTC)

I have no idea what you're trying to say. The OP asked about planetary systems in the Milky Way. You're talking about cosmology. Cosmological effects are utterly negligible on the scale of a galaxy, especially because the expansion of space does not affect gravitationally bound objects like galaxies. The answer to the OP is still "orbital planes are randomly oriented". --Bowlhover (talk) 16:44, 14 May 2013 (UTC)

Sorry if my post was unclear. I was attempting to describe why, from first principles of physics, we expect random alignment of the orbital planes, irrespective of the various length-scales we choose for our observational sample. If you still find my explanations unclear, you might consider reading my favorite resource on the topic, de Pater and Lissauer, Planetary Science, which spends most of chapter 13 discussing formation and evolution of stellar discs and describes their constraints by applying physical principles to inferred cosmological initial conditions. Perhaps my regurgitation of these concepts was a little more disordered than a textbook explanation. Nimur (talk) 18:02, 14 May 2013 (UTC)

Apparently Nimur's given a theoretical argument against, while these images show that our ecliptic is not aligned to the galactic plane. It appears the answer is that there is no evidence in favor of the hypothesis that planetary systems within our galaxy are aligned. I suspect that makes sense for any system that evolved from a nebula that was not coeval with the original condensation of the galaxy, given the alignments of nova ejecta would not be expected to align with the galactic plane. Does that sound correct? μηδείς (talk) 02:09, 15 May 2013 (UTC)

Determination of titratable acidity in apple juice

Hi! So this is our project (sort of) for an analytical chemistry lab. And If get the idea, since the commercial apple juice (which is what we're gonna use) is more or less colorless we can use an indicator (I'm unsure of whether they'll give us pH-meters and I'm not gonna risk) and apparently Malic acid is the dominant acid in apple juice (the natural one at least) and I've read in sources here and there that at least for the apple juice the pH of equivalence point is about 8, which helps me choose an indicator. The problem, however, is that I need a reliable source on the internet which I can use to cite, and Google searching it didn't give me any method which cites reliable sources. so where can I find a source for that? (sorry for potential grammatical/spelling errors)--Irrational number (talk) 18:47, 13 May 2013 (UTC)

The equivalence point will depend on which base you are titrating with, but if you are using a strong base like NaOH, then you need to calculate the pH of sodium malate, which will be the only species present at the equivalence point. There's a description of how to do so here, it's not hard if you know how to do pH calculations in general. Since you're calculating the pH of a solution of a weak base (sodium malate), you need it's Kb=10^-14/Ka of malic acid (obtained from the malic acid article). If you have an estimate of the concentration of the sodium malate (based on what you expect the concentration of malic acid is in apple juice) you can make a decent guestimation of what pH the equivalence point will be. --Jayron32 21:00, 13 May 2013 (UTC)

Thank you, but I was actually looking for a source I could cite for writing my lab report. It's so important for them.--Irrational number (talk) 09:46, 14 May 2013 (UTC)

The source you cite is any source for the Ka of malic acid, as it is the only number you need to look up, rather than calculate. All of the rest of the numbers either come from the lab procedure your teacher gave you, or you calculate them. The Ka values are given in the Wikipedia article, but if your teacher doesn't want you to cite Wikipedia, the values have a footnote so you can follow that to a non-Wikipedia reliable source. --Jayron32 12:39, 14 May 2013 (UTC)

Yeah, but I need a source for the procedure, not the values that I need. The teacher didn't give us any procedure, she asked us to find one for determining the titratable acidity of apple juice. I can think of a procedure (calculating the pH value of the equivalence point by estimating the concentration (and choosing the best indicator for it), making NaOH, standardizing it, using it to titrate the sample in presence the proper indicator), but I don't have any source that says this is the right procedure. I know science must not be based so much on authority and all that, but that's what they want from us... Sorry if I'm annoying...--Irrational number (talk) 13:06, 14 May 2013 (UTC)

The source of the procedure would be the source for any titration of a weak, diprotic acid with a strong base, which isn't functionally different than any titration. Literally every single general chemistry lab manual for first year chemistry students at both high school and college level has a titration lab like this. The procedure itself doesn't have to be modified from any titration, except that malic acid is a diprotic acid, so has two equivalence points. --Jayron32 21:07, 14 May 2013 (UTC)

May 14

has solar system sidereal rotation

As the sun and solar system rotate round center of milky way galaxy per 220milion years , it is clear that the system might rotate sidereal round sun , is there any information about such rotation? "I have inventive idea for this fact".--Akbarmohammadzade (talk) 05:23, 14 May 2013 (UTC)

May it be tidal locked or faster ,i suppose it be faster , but not be sensed by man for his short duration of observation time !!--Akbarmohammadzade (talk) 05:23, 14 May 2013 (UTC)

Sidereal just means "in an inertial frame of reference", that is, with respect to essentially motionless objects outside of the system being measured. Sidereal measurements of motion refer to measurements made against such a background; thus a sidereal day is the earth's rotation as measured against the stars, rather than the sun, which defines a solar day. I'm not how you are using it in this context. --Jayron32 06:11, 14 May 2013 (UTC)

May be the solar system ,or global stars or whole Orion cloud rotate round any center of mass ,when we are moving round center of galaxy . the planet day is its period of self rotating , i want to see , either the solar system or the global stars ,or Orion cloud has self rotating .then the sidereal rotation comes from comparing any inertial frame of reference, may it be very difficult to observe .(for the reason of our short duration of observation time)--Akbarmohammadzade (talk) 06:33, 14 May 2013 (UTC)

Our sun follows an orbital path around our galaxy. The timing of this orbital period will be perturbed by any orbital path through the universe that the galaxy may take, if the timing is with reference to something external to the universe. We have no such reference. Some boffins think that the universe does rotate, but as you surmised, it is difficult to prove. No accepted theory requires it. It has no practical importance. Wickwack 60.230.230.117 (talk) 06:45, 14 May 2013 (UTC)

Why it has no practical imortance? A.M IRAN— Preceding unsigned comment added by 81.12.40.3 (talk) 14:51, 14 May 2013 (UTC)

We don't live long enough to notice the difference, and even as an evolving species, are not likely to. There is conjecture that the universe is ~17 billion years old. If our descendents are still around in another similar length of time, we might be in a postion to notice. But without a reference frame outside the universe, we can never be in a position to know anyway. And if we solve that one, we would still have to develop clocks billions of times better in precision that the best atomic clocks we have now, in order to measure the variation. Wickwack 120.145.220.218 (talk) 15:08, 14 May 2013 (UTC)

when the sun and its global system for example alpha-Centures and orion cloud are rotating round any center of mass , then the branch of galaxy which we are in has special form of equilibrium. inthe other hand if the solar system does rotate so ,that has other meaning . how can any branch of galaxy be able to have both movement and save its own shape?A.M IRAN

Does it mean that we have special gravitational dynamic in galaxies other than planetary system ?A.mohammad zade IRAN — Preceding unsigned comment added by 81.12.40.3 (talk) 15:06, 14 May 2013 (UTC) Lets I name this Dynamics ""galactic rotation""

I have no idea what you are trying to say. I realise that English is not your first language, but please take more care to write clearly. Wickwack 120.145.220.218 (talk) 15:10, 14 May 2013 (UTC)

To a good approximation, the solar system is orbiting the galactic center without rotating the plane of the ecliptic. See conservation of angular momentum. To visualize this, assume taking a plate, holding in vertically in front of your breast, and walk in a circle around some fixed object, but always facing (e.g.) north. The plate will always be oriented along the east/west axis. Of course, the sideral period is originally observed with reference to the fixed stars, and for time periods similar to the orbit of the sun around the center of the galaxy (~250 million years), there are basically no fixed stars ;-). --Stephan Schulz (talk) 15:28, 14 May 2013 (UTC)

"Nipple delay"?

Reading the coverage of Angelina Jolie's preventative mastectomy, I saw the term "nipple delay" mentioned. Some Googling suggests that this might be this: http://www.ncbi.nlm.nih.gov/pubmed/22829005 , but this just refers in turn to a "surgical delay procedure" -- as in "Surgical delay is a technique that has been used for more than 400 years to improve survival of skin flaps." Does anyone know what this might involve? Is it the same thing as "delay of flap" (see http://www.springerreference.com/docs/html/chapterdbid/349885.html ) -- The Anome (talk) 08:53, 14 May 2013 (UTC)

As per http://www.ncbi.nlm.nih.gov/pubmed/15871701. It's not a common procedure, even in traditional nipple-sparing surgery. The vascular supply through the underlying glandular breast tissue to the nipple is obstructed (usually coagulation) under LA, and the nipple then left in place for two weeks or so for vascular collaterals in the skin to open up. Nickopotamus (talk) 23:15, 14 May 2013 (UTC)

Animal defense

Shimmering behaviour in Giant honeybees

Where in Wikipedia is an article about patterns of defense tactics of animals (show of force, threatening, pasive/active defense)? Examples: peacoks spread feathers, cats make themselfs big (fur and corpus), some tropical fish form schools, and some beatles make loud noises. --77.4.36.43 (talk) 10:17, 14 May 2013 (UTC)

Beatles do indeed make loud noises (or did, anyway, until Yoko Ono came along...) 24.23.196.85 (talk) 23:51, 14 May 2013 (UTC)

Ethologists usually classify some of those as agonistic behavior. There is also some info at territory_(animal). Then there is herd behavior which covers some of the others. For the "passive defense", see Armour_(anatomy), and maybe animal coloration. Does that cover all your examples? I'll check back later. SemanticMantis (talk) 12:38, 14 May 2013 (UTC)

I would agree, though, that we could legitimately have an overview article on that topic. Unfortunately high-level articles like that are the hardest kind to write, since they require the greatest level of expertise. Looie496 (talk) 14:26, 14 May 2013 (UTC)

I was thinking the same thing. Maybe it would be appropriate to start a stub (rather than limiting and contentious redirects)? For instance, a page titled "Animal defense" that has the above links, and a few more, separated into behavioral and morphological... SemanticMantis (talk) 16:11, 14 May 2013 (UTC)

That'll be great, too bad I'm not a behavioral scientist. --77.4.36.43 (talk) 16:48, 14 May 2013 (UTC)

Big Bang

Why is the expansion of the universe evidence for the Big Bang? That sounds like horseshit to me. Thats the equivalent of seeing a car going eastward on the M25 and concluding "that car started its journey in South London". Aren't physicists similarly jumping to conclusions? Pass a Method talk 10:25, 14 May 2013 (UTC)

That's not a fair comparisson - the M25 just keeps going and going, there is no end of the road where you can't go any further. The whole point of the expansion evidence, is that there is such a limit, where you can't go further back in time. Plasmic Physics (talk) 11:15, 14 May 2013 (UTC)

Technically the M25 doesn't 'just [keep] going and going' - there's a break for the Dartford Crossing. AndrewWTaylor (talk) 13:37, 14 May 2013 (UTC)

Moreover, the M25 has many intersections, the car could have driven onto the M25 by any one of those. The Big Bang expansion has no intersections, it started at a specific point in time. We've got no evidence to the contrary. Plasmic Physics (talk) 11:21, 14 May 2013 (UTC)

Is there any other evidence for the Big Bang besides expansion? From my perspective, the expansion of the universe could be explained by a modified version of the Big Bounce - perhaps an infinite universe without the gravitational singularity. Pass a Method talk 11:40, 14 May 2013 (UTC)

Cosmic Microwave Background radiation is predicted by, and consisted with, the Big Bang theory; an expanding universe which did not originate in a singularity might not be expected to have this. AlexTiefling (talk) 12:14, 14 May 2013 (UTC)

Actually, as far as I understand it (and this is hazy, year or so old knowledge from a physics degree), the CMB originates from the surface of last scattering, rather than the singularity itself, so a "big bounce" type theory which gets close to, but does not reach, a singularity would still show CMB similar to what we see now. Of course, with any such theory you run into the problem of the regions where it is substantially different being near impossible to observe. 91.208.124.126 (talk) 12:33, 14 May 2013 (UTC)

What happened before the Big Bang is a whole different pot of stew. Feel free to adhere to any theory you like, like the Big Bounce. Expansion only indicates the starting point of the Big Bang. Plasmic Physics (talk) 12:45, 14 May 2013 (UTC)

Try reading the article Big Bang (it exists for a purpose). The first two sentences of section Timeline of the Big Bang should tell you that the singularity is the result of an extrapolation of the standard cosmological model beyond the range of validity of known physical theories (general relativity and quantum mechanics). Simply put, the "big bang" (i.e. the singularity) is not actually part of "big bang theory". From observations we can infer that the universe was hot and dense at earlier times. This is directly observable to the last scattering surface/recombination when the CMB originated, temperature about 3000 K; indirectly to much earlier times based on a cosmological model with the observable universe given as initial conditions.--Wrongfilter (talk) 13:13, 14 May 2013 (UTC)

(edit conflict) Also note that the so-called "singularity", that is the point of infinite density with zero dimensions, is not itself actually proven, or even well believed, by anyone. Mathematical infinities show up frequently in physics calculations, but whenever we run into such an infinity, it is generally taken to mean that, at some arbitrarily large or small point, our theories cannot any longer match reality. See Gravitational singularity, for example, which states "Many theories in physics have mathematical singularities of one kind or another. Equations for these physical theories predict that the ball of mass of some quantity becomes infinite or increases without limit. This is generally a sign for a missing piece in the theory, as in the ultraviolet catastrophe, renormalization, and instability of a hydrogen atom predicted by the Larmor formula." (bold mine). That is, what we call the Big Bang is the massive expansion of the universe from its initial state; while most models take that initial state to be a singularity, that singularity just means "our theories break down as we get that far back" not "there really was an infinitely small point". The "Big Bang" itself could be taken to mean cosmological inflation, which was a period from .000000000000000000000000000000000001 seconds after creation to .000000000000000000000000000000001 seconds after creation. We have some grasp on what happened before that, down to perhaps the Planck epoch, which ended .0000000000000000000000000000000000000000001 seconds after creation, though often the term includes all of the events that happened from creation through the inflationary period. There are still many unanswered questions about how certain things happened in the transition from these very early time, such as Baryogenesis and Baryon asymmetry, or why we have more matter than antimatter. --Jayron32 13:06, 14 May 2013 (UTC)

'Bang' is a misnomer, that's been established, it's more like a 'Hum'. I guess, it's a bang in the sense of the rapidness of the event. In any case, something certainly went 'Big', that's been settled. Plasmic Physics (talk) 13:35, 14 May 2013 (UTC)

The evidence that should convince a lay jury to find the Big Bang guilty is:

1) The universe is expanding (galaxies are receding approximately according to Hubble's law).

2) Existence of the cosmic background radiation.

3) The age of the oldest white dwarf stars as inferred from the cooling rate is below the age of the universe as inferred from the expansion of the universe, while a hypothetical white dwarf of hundreds of billions years old would still be easily detectable.

4) The present day ratio of the abundance of hydrogen, helium and deuterium exactly fits the prediction of the Big bang model.

Count Iblis (talk) 13:48, 14 May 2013 (UTC)

My contention is mainly with the gravitational singularity in the Big Bang model. Not the rest. Pass a Method talk 13:53, 14 May 2013 (UTC)

As others have pointed out above, the Big Bang model is only useful to explain the evolution of the universe from some age onward. It has to break down when the universe was very young. We know this because the extremely high temperatures predicted by the Big Bang model would have led to the creation of magnetic monopoles and so much energy would have been in the form of these monopoles that the universe would have closed in on itself and collapsed soon after the Big Bang. This and other problems (e.g. the fact that the cosmic background is extremely uniform) are fixed by the inflation model. Count Iblis (talk) 14:02, 14 May 2013 (UTC)

When you use words such as "young" you are implying that we know whether the universe is infinite or not. The reality is we don't know. Let's be humble here Pass a Method talk 15:32, 14 May 2013 (UTC)

At that level, we don't know anything beyond our own existence, individually speaking (see solipsism). At some level, we need to accept an amount of uncertainty. The level of uncertainty present in modern scientific cosmogeny is not significantly more than the level of uncertainty necessary for you to operate in the world, and certainly not more so than any other branch of science. We have a pretty good handle on stuff down to pretty small units of time from the moment of creation. Science is very humble, but it also requires us to accept, until shown to be incorrect, theories that match observation well. And most of the theory in this case matches observation very well. --Jayron32 15:55, 14 May 2013 (UTC)

Let's not be pedantic either. It's perfectly OK to describe the universe as young without implying that nothing happened before the Big Bang. We don't know if the universe really started at the Big Bang but we can take the Big Bang time as time = zero, and measure the age of the universe from there. Dauto (talk) 15:58, 14 May 2013 (UTC)

The talk of "creation" is fruitless. We admit we have no idea what things would be like in the Planck epoch (and indeed, disputes about what happened later are so severe that the lay person gets the notion that at least some physicists don't know anything about what happened then). So we have no real proof of any kind that there was a "moment of creation", or what that means; it is a point where the math and theory breaks down. Wnt (talk) 16:54, 14 May 2013 (UTC)

Creation is as good of a word as any for that moment we define as the "zero" spot for our calculations of events as they occurred in what we call the "young" or "early" history, with all of the silly caveats we have to throw in about us not knowing if it is a real "zero" or merely an impenetrable barrier beyond which we can't measure, but still exists, and for which all of the other caveats we have to put on words like "early" and "young" and all that. But there's nothing inherently wrong with the word itself, it's a good heuristic word for a concept which, under Occam's razor, is the simplest explanation for what happened before that moment (i.e. "nothing", which is simpler than "something we can't ever know about, as far as we can tell") --Jayron32 19:42, 14 May 2013 (UTC)

Not to mention Last Thursdayism, which pretty much makes the idea of "creation" unfalsifiable. -- The Anome (talk) 18:46, 14 May 2013 (UTC)

That's certainly true - and can be taken to the extreme by saying that the only thing that exists is this precise instant - with time not existing at all - so no past and no future whatever. However, even in such a world-view, it is scientifically reasonable to ask why there are all of these signs and symptoms that make it look an awful lot like the universe was created 14 billion years ago - and to study those signs and symptoms to see why last Thursday's creation process resulted in such a bizarre set of seemingly self-consistent facts. If the universe was created last Thursday, why does it have cosmic background radiation? Certainly we can't falsify last-Thursdayism - but Occam's razor says that: like religion, the existence of ghosts and Russel's teapot - we're better off ignoring the unfalsifiable and pressing on with the study of what we can actually measure and conduct experiments upon. Occam's razor doesn't have the force of law - but its a damned good principle that is right a lot more often than it's wrong. SteveBaker (talk) 19:41, 14 May 2013 (UTC)

The Universe

I've always wondered, say the Universe is finite, it must have shape, right? If so, what is outside the shape? And since the Universe is said to expand, where is it expanding into? Say it were infinite, could the human mind ever comprehend how it looks like? ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 12:52, 14 May 2013 (UTC)

Start at Shape of the Universe and read on. --Jayron32 13:10, 14 May 2013 (UTC)

Short answer: nobody knows. Pass a Method talk 13:27, 14 May 2013 (UTC)

That's a terrible short answer! Here is a better short answer: cosmologists use the word "shape" to mean something different from what many people think. If you would like to learn what they mean, you'll need a longer answer, as others have pointed out. Nimur (talk) 15:55, 14 May 2013 (UTC)

It could have a topological configuration (eg a hypertorus) without needing to be embedded in any real higher space, so 'outsideness' does not necessarily enter into consideration. AlexTiefling (talk) 13:28, 14 May 2013 (UTC)

Yes, and hypertorus should probably redirect to Torus#n-dimensional_torus, which has a very nice animation. SemanticMantis (talk) 14:19, 14 May 2013 (UTC)

From our article on infinities, Infinity#Cosmology: "In 1584, the Italian philosopher and astronomer Giordano Bruno proposed an unbounded universe in On the Infinite Universe and Worlds "Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds." Modocc (talk) 14:24, 14 May 2013 (UTC)

It's hard to mentally visualize a finite shape without boundaries - but imagine that if the universe was MUCH smaller than it really is...say no bigger than the solar system. Now imagine you have an impossibly good telescope, then you could look towards the horizon - see the earth as a tiny dot out in space - then zoom in and see the back of your own head - you could look straight up and (if you're standing someplace in North America) see another copy of the earth - and zoom in to see the middle of the pacific ocean. Space itself could be curved back around in some extra dimension and looped back on itself...and it might do that in every direction you could look. What you'd see would be time-delayed, repeating copies of the same volume of space in every direction.

That wouldn't work in practice for a couple of reasons - one being that the speed of light wouldn't allow you to see that far without you seeing something from the impossibly distant past, before stars and planets existed - the other related problem being that no matter what, the "observable universe" is still smaller than the complete universe.

But it's certainly possible (even quite likely) that there are no boundaries and yet the universe can still be finite. That's a weird thing to comprehend - but no weirder than an infinite universe.

In a sense though, it doesn't matter. No matter which way we look, or how good our telescopes may become, the further we look in distance, the further back in time we see - so out beyond 45 billion lightyears, all we can see in any direction is the big bang. SteveBaker (talk) 16:59, 14 May 2013 (UTC)

• Imagine the universe is the size of a room in a normal sized house, with all the galaxies floating in it like motes of dust. That room has four walls, each with a door in it, and trap doors on the floor and ceiling. If you open the door facing east, the door facing west opens and you step in from the west as you leave from the east. Likewise north-south, and floor ceiling. Now imagine the doors are gone and you can see the back of your head by looking through any doorway. Now imagine the doorways expand and the walls disappear until there is no framework to the room any more, just a universe the size of the room in which it is possible to move in any direction infinitely without coming to a boundary. That is an finite unbounded universe. μηδείς (talk) 17:11, 14 May 2013 (UTC)

• There is a natural intuition for people who haven't studied advanced geometry that a curved space is always embedded in a higher dimensional flat space -- in the same way we visualize the surface of a sphere as embedded in 3-dimensional Euclidean space. But that's a false intuition. It is mathematically possible to have a curved space without having it embedded in anything, and even if it is embedded, it may be impossible to infer properties of the embedding space from the properties of the curved subspace. Looie496 (talk) 17:13, 14 May 2013 (UTC)

• For a smooth curved space it is generally true that one can do all the math one ever needs to do simply by considering local changes within the space. It is also true that any smooth curved space with a finite number of holes can always be mathematically embedded in a higher dimensional flat space. Whether or not such an embedding is useful will depend on the details of the problem one is considering, but the existence of such an embedding is really a statement about the nature of mathematics rather than anything physical. If people want to imagine that the universe lives within some empty, flat, higher dimensional space, then they are free to do that. Whether or not it is ever actually useful to do that is a separate issue. Dragons flight (talk) 18:17, 14 May 2013 (UTC)

As Dragons Flight says, it's possible to embed any any sufficiently well-behaved manifold in a higher-dimensional flat space, if only formally, for the purposes of discussing it, so it's not a bad way to visualise these things if you can't rid yourself of imagining everything in terms of curved things embedded in Euclidean space. -- The Anome (talk) 18:20, 14 May 2013 (UTC)

I find this stuff totally counter intuitive and mind bending. The thing to remember is that there isn't ANYTHING outside the universe. It's not like there is a boundary at the perimeter of the universe, like a bubble, with "universe stuff" on one side and some kind of "other stuff" on the other. It's kind of meaningless to talk about 'shapes', our normal undetstanding of things completely breaks down. Vespine (talk) 22:55, 14 May 2013 (UTC)

Do you find the room analogy I gave difficult, Vespine? μηδείς (talk) 02:01, 15 May 2013 (UTC)

Sucrose gradient

Why doesn't the sucrose in a sucrose gradient diffuse to reach equilibrium and thereby eliminate the gradient? — Preceding unsigned comment added by 129.215.5.255 (talk) 15:32, 14 May 2013 (UTC)

Doesn't it? Dauto (talk) 15:34, 14 May 2013 (UTC)

The diffusion equation can reach steady state with a non-zero gradient only in certain conditions - when there is a source or sink external to the region in consideration. In your application, do you have a source or sink (inflow or outflow)? Nimur (talk) 15:43, 14 May 2013 (UTC)

I was curious about this myself long ago and forgot to look it up - good question! In a sucrose gradient centrifugation, in biology, different concentrations are layered on top of each other in a closed tube. The point is that diffusion is slow: specifically, the diffusion coefficient is 520 um^2/s [7] or 5.7 x 10^-5 cm^2/s [8]. (The precise value depends on your conditions but let's take the second 0.0057 mm^2/s since the first looks crowdsourced) According to Fick's laws (the first), the rate of flow is proportional to the gradient in space - if you have a 30% difference in concentration over a distance of, I dunno, say 10 cm, then you dphi/dx = a constant (you hope) 0.3% / mm difference . J = -D dphi/dx = 0.0017 % mm/s, i.e. 0.0017% crosses a mm distance in one second. In order for the entire gradient to break down to 15% across the board, 15% has to cross the centerline, which would take 147 minutes ... except the gradient, and so the motive force, gets weaker and weaker and so it trails off exponentially over time. But this gives a first-order sense of how the gradient can last long enough. Wnt (talk) 16:30, 14 May 2013 (UTC)

3 core 0.229in diameter wire vs 7 core 0.229 in diameter wire pure copper

How do these wire compare ? which one is better for upto 20 amp DC current ?

I don't think there will be much difference in conductive properties, but the 3-core wire will be quite a bit stiffer -- harder to break, but also harder to bend. Looie496 (talk) 17:08, 14 May 2013 (UTC)

There would be a significant difference in conductive properties at high frequencies because of the skin effect - but nothing really measurable at DC. That said, if the overall diameter is the same (0.229"), can you get more cross-sectional area with three circles or seven? Gut feel says that you get more copper and less air with seven cores than with three...but I'm not enough of a math whiz to know for sure. If you really care (and I doubt you need to!), get a length of each and weigh them...since the plastic sheath isn't likely to weigh much, whichever wire is heaviest should have more copper and hence less resistance at DC. SteveBaker (talk) 20:12, 14 May 2013 (UTC)

Sorry, I didn't mean to say that the conductivity is the same for both, just that it's so high as not to matter except in some sort of extreme application such as wires that are miles long. For either one of them, a kilometer of wire has a resistance on the order of 1 ohm. Looie496 (talk) 21:08, 14 May 2013 (UTC)

Not necessarily true. The OP asked about DC. If the source of DC is a 12 V lead acid battery, and the 20 A load is 25 m (~ 75 feet; taking into account go and return, routing within and around buildings etc, this could be almost just the next room), then the voltage drop in the cable would be 1 V, about enough to loose 8% of the power, and seriously compromise the operation of the load. Wickwack 121.215.78.174 (talk) 00:28, 15 May 2013 (UTC)

Did Prafulla Chandra Ray discovered Mercurous nitrite?

Can any expert in chemistry explain me if Prafulla Chandra Ray discovered Mercurous nitrite. I am really confused reading the wikipedia article and The Telegraph article 1. Solomon7968 (talk) 17:34, 14 May 2013 (UTC)

See http://www.ias.ac.in/resonance/Jan2001/pdf/Jan2001p42-49.pdf for a full account. Looie496 (talk) 17:45, 14 May 2013 (UTC)

What do you call the inverse of speed?

Hi,

Speed is (distance travelled)/(time taken) . Is there a specific word for the inverse of speed that is (time taken)/(distance travelled) and would have units of seconds per meter.

Thanks, Gulielmus estavius (talk) 18:11, 14 May 2013 (UTC)

Sloth? μηδείς (talk) 18:23, 14 May 2013 (UTC)

(Could you please use a <small> tag - or some other means to indicate when you're joking - this is a potentially confusing answer...I'm fairly sure sloth isn't the scientific term for inverse speed - and certainly your link doesn't indicate that)

Could you stop using Wikipedia as an alternative to Facebook or Twitter please Medeis? You may find your own jokes amusing but most of the people who don't know your "style" have no idea what you're talking about. Thanks. The Rambling Man (talk) 20:39, 14 May 2013 (UTC)

I am not joking. If you bothered to look at the source, rather than your own emotional content, you'd see the word sloth means slow-th, i.e., slowness. μηδείς (talk) 22:25, 14 May 2013 (UTC)

I would call sloth or slowness the opposite of speed, using speed as a relative term. Speed as a measurement is distance over time, so the inverse would be time over distance. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:08, 14 May 2013 (UTC)

This abstract kinda suggests that "slowness" has been used - but there clearly isn't a formal SI derived unit like the "siemens" or "mho" is sometimes used as a reciprocal ohm or "hertz" as reciprocal seconds. SteveBaker (talk) 18:58, 14 May 2013 (UTC)

Hertz is NOT a unit for reciprocal seconds. Hertz dimensionally is 1/T, but Hertz is reserved for expressing the frequency of a periodic function that can be measured by cycles per second. There are other phenomena that are dimensionally 1/T that are not cycles per second and are thus not expressed in Hertz. For example, angular velocity (expressed in radians per second) also has dimensions of 1/T. And, obviously, if it takes me (say) 40 seconds to type this, and I express that as (0.025 Hertz)^-1, you'll rightly think I am a complete idiot. Also note that under SI, Hertz is defined in terms of atomic phenomena. If for some reason you are measuring the frequency with reference to sidereal time, the correct way to express it is as "cycles per second". Wickwack 121.215.78.174 (talk) 00:45, 15 May 2013 (UTC)

The perm (unit) coincidentally cooks down to (some multiple of) the same base units – if you cancel all the units in kg/s/m^2/Pa, then you get s/m left over – but obviously isn't quite what the OP is looking for. TenOfAllTrades(talk) 19:19, 14 May 2013 (UTC)

No scientific term exists, but there's one in popular culture: the "minute mile". See four-minute mile, for example. --Bowlhover (talk) 19:52, 14 May 2013 (UTC)

OK so the inverse of speed is journey time. Sussexonian (talk) 21:48, 14 May 2013 (UTC)

No, that has the dimensions of time: it's actually got to be journey time per distance: units of time-per-distance, in order for things to work dimensionally. -- The Anome (talk) 22:42, 14 May 2013 (UTC)

I think Journey time works, journey implies distance, a journey of zero distance is not a journey. Vespine (talk) 22:49, 14 May 2013 (UTC)

The inverse of Electrical resistance as measured in Ohms is conductance, as measured in Mhos (Mho is Ohm backward, of course). So by that logic "Speed" could be "Deeps". There doesn't appear to be a standard unit for this, so maybe you could invent your own. As a matter of pure nosiness, why do you ask? Tonywalton ^Talk 01:01, 15 May 2013 (UTC)

Well, the invent-your-own answer is obviously superseded by sloth, but the "deeps" idea is worth extra credit! μηδείς (talk) 02:00, 15 May 2013 (UTC)

In SI, if you want to quote something as a reciprocal of speed, the convention is to just express the the numerical value with the units, as in 20 seconds per metre. Note that SI does not have names for everything (that would be impossible), and actually has a unit name for only relatively few things - generally things that had a unit name in the MKS, CGS, or Ft.Lb.Sec systems. For example, absolute viscosity is quoted in SI as Pascal-seconds (Pa.S). Wickwack 121.215.78.174 (talk) 00:56, 15 May 2013 (UTC)

you can "return back" or at distance or at time . thanks Water Nosfim --81.218.91.170 (talk) 04:53, 15 May 2013 (UTC)

May 15

Is this an artifact?

Rock may be an artifact

Could this rock be an artifact? Note the hole through it. It is almost 7cm long. Bubba73 ^{You talkin' to me?} 00:06, 15 May 2013 (UTC)

I'm absolutely not qualified to say, but look at kettle hole. I think you can have hydraulic drilling on a very small scale under certain circumstances, but certainly I cannot tell you this is the case here. Wnt (talk) 01:22, 15 May 2013 (UTC)

Holes caused by dripping are much wider than this due to splashing. μηδείς (talk) 01:57, 15 May 2013 (UTC)

The hole is about 3.5mm wide on one side and nearly 4mm on the other side. Bubba73 ^{You talkin' to me?} 02:03, 15 May 2013 (UTC)

The hole is through the thinner part of the rock and it is nearly 1 cm thick there. Bubba73 ^{You talkin' to me?} 01:27, 15 May 2013 (UTC)

I noticed that there are two small indentions on both sides next to the hole - those must be signs of how the hole was made by people. See File:Rock hole back.jpg and File:Rock hole front.jpg. Bubba73 ^{You talkin' to me?} 02:39, 15 May 2013 (UTC)

Where is it from? HiLo48 (talk) 02:50, 15 May 2013 (UTC)

I don't know. My wife found it but she doesn't remember where. We live in the state of Georgia, so I asked her if it was in Georgia, but she doesn't remember. Bubba73 ^{You talkin' to me?} 03:55, 15 May 2013 (UTC)

• I'm no expert here, but I doubt the hole was created naturally. I'd lean towards something Native American, but that's a guess. I found a similar item online here but the description given isn't helpful. Have you contacted your local historic society, they'd probably have some better answers. Hot Stop 04:05, 15 May 2013 (UTC)

I have not contacted a historical society. I ran across it cleaning out a box of stuff today. I don't remember it, but my wife says that she found it. I suspect native American too - there are such artifacts around here. It looks like the hole was to put a cord through it. So maybe it was worn, used as a toy, or a weapon. Bubba73 ^{You talkin' to me?} 04:16, 15 May 2013 (UTC)