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September 13

Tropical storms and hurricanes: codes and numbers

I had posted this on the Humanities Help Desk (by mistake). I am now moving it over here, to the Science Help Desk. Thanks. Joseph A. Spadaro (talk) 04:33, 13 September 2017 (UTC)

Please see this article (list): Tropical Storm Irma. What do all of those codes and numbers mean? For example, one storm on this list – Typhoon Irma (1985) – has a notation that reads "(T8506, 06W, Daling)". I have no idea what any of that means. Does anyone know? Thanks. Joseph A. Spadaro (talk) 23:40, 11 September 2017 (UTC)

The Growth number corresponding to this first name is 11. Aside from that, Daling's just a name, not a code. No clue about the numbers. InedibleHulk (talk) 23:45, September 11, 2017 (UTC)

My first thought for "06W" was "West", i.e. it travelled 6 degrees east-west. Consider these four storms:

• 1985, 06W
• 1978, 19W
• 1981, 26W
• 1974, 34W

As you go down the list, each one had a net east-west difference that's greater than the one above it. That got shattered, however, with the 1971 storm, 37W, which started and ended near the Philippines. Their starting locations aren't correlated with the numbers either (e.g. 1971 and 1985 both started vaguely near Guam), so the numbers definitely don't mean "degrees west of the antimeridian". Nyttend (talk) 01:37, 12 September 2017 (UTC)

The numbers line up quite well with their chronological order in the typhoon seasons. InedibleHulk (talk) 01:59, September 12, 2017 (UTC)

The first name is assigned by Joint Typhoon Warning Center (JTWC) in Hawaii. The second name was used when it was in "area of responsibility" of the Philippine Atmospheric, Geophysical and Astronomical Services Administration. Perhaps the number was assigned by the Japan Meteorological Agency (JMA)? Rmhermen (talk) 01:39, 12 September 2017 (UTC)

Maybe ask User:HERB, who added them back in 2009, who made some edits the other day, and who is even named after such a storm. PointyOintment (talk) 05:09, 12 September 2017 (UTC)

Thanks. I posted on his Talk Page. And I asked him to offer some input in this discussion. Thanks. Joseph A. Spadaro (talk) 05:19, 12 September 2017 (UTC)

I believe this is the 6th tropical depression of 1985 in the Western Pacific (I don't know if subtropical depressions count). Atlantic storms are called L (01L, 02L and so on), Invests (potential tropical depressions) are called 90L, 91L through 99L then 90L, 91L and so on and other basins have other letters like E for East Pacific. The "L" is probably for AtLantic. Sagittarian Milky Way (talk) 05:41, 12 September 2017 (UTC)

And typhoons near the Philippines also have a Philippines name which is probably what the name in parentheses is. PAGASA might mention this. Sagittarian Milky Way (talk) 04:38, 13 September 2017 (UTC)

I have now moved this to the Science Help Desk. Thanks. Joseph A. Spadaro (talk) 04:31, 13 September 2017 (UTC)

Thanks, all. Joseph A. Spadaro (talk) 15:13, 15 September 2017 (UTC)

Humans shaped by partners

How much of out genes is a results of what our mates chose as appropriate or desirable? What traits died out because no one wanted to mate with humans carrying those traits? --B8-tome (talk) 18:58, 13 September 2017 (UTC)

See sexual selection. But note that only a tiny portion of genes are different between men and women (1 in 46 chromosomes is different, X versus Y, but not entirely different), and presumably only a small portion of those differences are due to sexual selection. If you want a specific trait that died out due in part to sexual selection, perhaps being covered with body hair might qualify. Being hairy meant they were more likely to have parasites like fleas and lice, and having those does tend to be a turn-off, because they can spread to mates. However, the use of animal skins as clothing was also critical in this process, as otherwise hairlessness can cause death from exposure. StuRat (talk) 19:33, 13 September 2017 (UTC)

This is very misleading. Only a small number of genes are differentially present in men and women, but a greatly larger number of genes are differentially expressed. The Y chromosome only contains a small number of genes, but those genes control the activity of many, many other genes located on other chromosomes. The small size of the Y chromosome really has no impact on the possibility of sexual selection. Looie496 (talk) 23:12, 13 September 2017 (UTC)

Note that sexual preference is itself subject to natural selection on the very long term. While this phenomenon was discovered in exceptional cases where sexual selection leads to a net disadvantage, sexual preference will have had an effect on evolution for many hundreds of millions of years and must therefore itself have been subject to natural selection. E.g. prey animals can happen to get into a situation where there are far fewer predators than usual for many generations. Sexual selection will then determine the genetic make-up of the offspring to a larger degree than usual. But the predators will be back later so, on the long term, a sexual preference that has a similar outcome whether there are are predators or not, is the one that's going to be selected for. Count Iblis (talk) 01:58, 14 September 2017 (UTC)

Proximity tends to be a huge factor in choosing a mate. It is rather uncommon for a person to mate with someone that is too far away. Instead, they tend to choose mates within the tiny group of people that they have contact with. 209.149.113.5 (talk) 11:40, 14 September 2017 (UTC)

September 14

'97% Of Climate Scientists Agree' Is 100% Wrong

According to this article, '97% Of Climate Scientists Agree' Is 100% Wrong, the 97% figure commonly cited in favor of scientific consensus on AGW comes from a paper (Cook) which misrepresented several scientist's work. Is there any truth to these papers being mischaracterized? In particular, I'm referring to page 2 of the article. If it is true, how much would it change the 97% figure? A Quest For Knowledge (talk) 13:57, 14 September 2017 (UTC)

The issue isn't that 97% of climate scientists agree. The issue is what they agree on. What they agree on is that there is a warming trend of up to 0.8 degrees in the last 150 years and they agree that there has been an increase in fossil fuels during the last 150 years. They do not all agree that the warming is completely caused by use of fossil fuels. They do not all agree that the trend will continue. They do not all agree that the trend will accelerate. They do not all agree that ending all use of fossil fuels will reverse the trend. However, this does not mean that less than 97% of climate scientists do believe that global warming is going to be an ongoing trend and that it is caused by man. This is the best analysis that I've seen on the topic of consensus. It makes it clear that while the consensus for any specific subject may be lower (or higher) than 97%, it is still well over 90% in general. 209.149.113.5 (talk) 15:09, 14 September 2017 (UTC)

• An opinion piece is not a reliable source. --Stephan Schulz (talk) 15:39, 14 September 2017 (UTC)

Also keep in mind what a moving target this is. New scientists are minted every year, scientists die every year, etc. There's really no use in nitpicking exact percentages on something like this. Science isn't a popularity contest. SemanticMantis (talk) 15:52, 14 September 2017 (UTC)

Also also important: Science is not built on single "gotcha" moments, nor is it built on certitude. It is built on consensus, and it is built on the preponderance of evidence. "I did the calculations, and it's only 96%! HA! It must all be a hoax!" is the sort of bullshit that the creationists and the ID crowd and the climate change deniers engage in. The fact that consensus is clear, evidence is overwhelming, and we're damned sure that climate change is happening and is caused by pollution are not in serious dispute. The disputes are over things like mechanism, degree, small differences in specific theory, and the like. The broad picture is well agreed upon. --Jayron32 15:59, 14 September 2017 (UTC)

Basically, if 97% of scientists can be wrong about something, the remaining 3% are probably even more wrong or Not even wrong (if they're even doing science at all). Ian.thomson (talk) 17:06, 14 September 2017 (UTC)

Rubbish blog talking about no change in the last 15 years. Even Roy Spencer's graphs show the trend even though he believes that God would not allow such a thing and he refuses to put in anything except horizontal average lines on his graphs. Dmcq (talk) 16:32, 14 September 2017 (UTC)

I am reminded of a discussion on Wikipedia's science reference desk in January 2017 in which we teased apart the actual, factual statistically-meaningful bit about a 95% confidence interval; and deconstructed a sound bite by citing the reliable source of information from which it originated.

The trouble is, certain journalists thrive on the use of imprecise language, weak attribution of claims, and unscrupulous use of statistical fact. These behaviors would be called "weasel words" if an author posted them to Wikipedia. In high-visibility newspapers, authors get paid for using these tactics!

Well-written scientific news carries at least the following characteristics:

• clearly-specified factual claims
• clear attribution of factual claims to a person or authority of merit
• reference to further information, data, and analysis for interested readers to explore the topic in further depth

If you're reading a science-news website that does not do all of those three things, you're not reading a good science news website.

In this case, the author of this Forbes opinion piece constructs a straw man argument. He poses questions that he does not expect us to answer, probably for the sake of promoting doubt. I would call that disinformation - or at the very least, pretty disingenuous, and poor-quality journalism, even for an op-ed piece. He writes: "What exactly do the climate scientists agree on?" Well, if he read the paper he pretends to be criticizing - Quantifying the consensus on anthropogenic global warming in the scientific literature (2013), the paper is pretty specific. "Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming."

Now, if the critics want to attack the methodology, that's fine - they can bring their legitimate criticisms. But if they simply ask obtuse questions - "What exactly do the climate scientists agree on?" ... then there are very easy answers to their ill-informed questions. The climate scientists agree that "humans are causing global warming." This is the statement that Cook et al. found agreement upon. "How do we know the 97% agree?" "We analyze the evolution of the scientific consensus on anthropogenic global warming (AGW) in the peer-reviewed scientific literature, examining 11 944 climate abstracts from 1991–2011... "[Cook et al] classified each abstract according to the type of research (category) and degree of endorsement."

See? Easy answers exist to refute an ill-conceived critique.

Perhaps instead of reading opinion-pieces on Forbes.com, our readers would consider reading a better science news website, where interesting and difficult questions about climate and policy are brought forward? Here's a front-page story from the website of the U.S. Energy Information Administration - EIA projects 28% increase in world energy use by 2040. What are we going to do about that? Why doesn't our esteemed op-ed writer tackle that question in his next piece?

Nimur (talk) 18:59, 14 September 2017 (UTC)

Well, the first page of the article is fairly easy to debunk. It was the second page I was more interested in. I was curious if these quotes were taken out of context or the article was omitting anything. So far, I've researched the first quote and it appears to be accurate. In fact the guy quoted, Richard Tol, did write an interesting article critiquing Cook's methodology: The claim of a 97% consensus on global warming does not stand up. What the Forbes opinion piece neglects to explain is that Tol was only criticizing Cook's methodology, not the scientific consensus on AGW. A Quest For Knowledge (talk) 19:26, 14 September 2017 (UTC)

The theory that the world is heating up is probably a result of statistical mis-analysis. The temperature records that have survived from 150 years ago are sparse and are heavily weighted in favour of capital cities, which are usually harbour cities and therefore cool. Since the 1960s a boom in technology has allowed the placing of temperature sensors in remote places where readings were never historically taken. A boom in computer technology since 1990 has allowed the storage of all this recent data. What we are seeing is not a rise in temperature but a more accurate figure for the world's temperature. I have never seen any analysis by scientists of the implications of this statistical bias. Akld guy (talk) 19:44, 14 September 2017 (UTC)

Akld guy, before you self-congratulate as the sole genius who has figured out the grand conspiracy, you should know the following.

You are making certain specific claims that are:

• commonplace claims often repeated by ill-informed people
• claims that are easily, and commonly, refuted by actual scientific study

Your claims are:

• The claim that urban heat islands are responsible for invalid data
• The claim that recent data or methodology is inconsistent with older data and methodology

Both claims are wrong.

• Urban heat island effect is very well known, very well characterized, and responsible climate-scientists account for this effect. Here is EPA.gov's website on the heat island effect; and here is the National Climatic Data Center's FAQ on temperature data. Refer to "Q5: Are there still biases in the data we use to calculate global and U.S. temperatures?"

Once again, we can easily refute your criticism. Your criticism is neither valid nor correct; and it's not even original. It's the same tired line that has been repeated by many poorly-educated people for, well, a really long time. Before you were even born, uneducated people were saying that urban heat islands perturbed climate science; they were wrong then, and they are wrong now.

Absent any reliable reference for your claim, you should not repeat your claim on this encyclopedia's science reference desk. You say you "have never seen any analysis by scientists of the implications of this statistical bias." Here are six analyses:

• [1]
• [2]
• [3]
• [4]
• [5]
• [6]

Do you really want more, or would you like to rescind your ill-informed commentary?

For your own sake, spend an hour studying climate science before making strong statements about it. Even better - spend a few thousand hours studying it - because that magnitude of formal study is exactly what climate science professionals get.

Nimur (talk) 20:03, 14 September 2017 (UTC)

Yeah, whatever. Scientists are not statisticians. You do realise don't you that adjusting for bias because of incomplete statistics from long ago is error prone? Extrapolating new figures based on a limited subset is prone to error. In short the comparison is being made on a limited set of figures, expanded out to give a multitude of new figures, versus the latest figures from sensors where readings were never taken. It's just nonsense. Akld guy (talk) 21:42, 14 September 2017 (UTC)

Scientists can be statisticians, or mathematicians, or whatever.

The author of the first study I linked, Tom Smith, has "degrees in mathematics, meteorology, and oceanography." I'd be willing to bet money that he's got three more degrees than you've got in the geosciences. Multiple universities, organizations, and agencies have validated his credentials; his papers passed peer-review, meaning that panels of experts in climate and statistics checked his work. I also cited many many more authors and publications, so if you don't like the first one, and you don't like the next paper, and you don't like the next author's credentials, and you disagree with the next paper's methodology.... well, the statistics just aren't in your favor, are they? How about 11,000 more research publications, do you still want to nitpick each of the authors' credentials on that stack of research as well?

If you disagree with the majority of experts, you are the fringe scientist crackpot.

This data is vetted by scientists and statisticians. The methodology is correct and sound. You are mistaken, and instead of being argumentative about it, you should take some time to inform yourself.

Nimur (talk) 21:53, 14 September 2017 (UTC)

Just to add a little bit here: the blogger Anthony Watts believed this exact thing - that urban heat island was affecting temperature records. To his credit, he investigated this scientifically, sending people to photograph weather stations and see how the environment around them had changed. In the end, the weather stations in urban areas didn't give a significantly different reading to those in rural areas (they gave slightly warmer night time temperatures and cooler day time temperatures, but these effects cancelled out), and even the best-sited weather stations showed a warming effect - see Anthony Watts (blogger)#Surface Stations project. Despite this, Watts continues to believe that global warming isn't happening, which pushes him "sceptic" to "denier" in my books. Smurrayinchester 09:24, 15 September 2017 (UTC)

The 97% figure does not just come from one paper. Four separate papers have estimated consensus at 97%, and three other papers came up 91%, 93% and 100%. Adrian J. Hunter^{(talk•contribs)} 10:08, 15 September 2017 (UTC)

So, the counter-argument I'm facing is that these studies misrepresent the papers. If you look at page 2 of the article, there are a series of quotes from scientists who say that Cook miscategorized their papers. I've been able to validate the first quote from Tol as accurate, albeit misleading. Tol does dispute Cook's methodology but not the scientific consensus on AGW. A Quest For Knowledge (talk) 10:29, 15 September 2017 (UTC)

Lighting a match in a hydrogen filled room

Imagine a room completely filled with hydrogen and no oxygen. A match is somehow struck in this room. Does it light? Does the room explode with flame? Or is oxygen needed for the reaction? Basically, does hydrogen require oxygen to burn? †dismas†|^(talk) 19:15, 14 September 2017 (UTC)

Hydrogen requires oxygen to burn. Flame, in the conventional sense, requires the three parts of the fire triangle: fuel (hydrogen); oxidizer (from the oxygen in the air); and a spark (the heat from friction during the strike of the match).

Interestingly, though, a match probably does not require oxygen from the air - depending on the type of match, it may contain (or may be struck against) an oxidizing chemical, allowing the flame reaction to occur (for a brief time) independent of any oxygen in the air. If the room is totally oxygen-free, that flame will rapidly extinguish.

Nimur (talk) 19:23, 14 September 2017 (UTC)

According to Flammability limit, the upper flammability limit of hydrogen in 75% in air, so no, the room does not explode. Yes, hydrogen requires oxygen to burn. shoy (reactions) 19:27, 14 September 2017 (UTC)

For the record, we're restricting to discussion of conventional chemical combustion. You need an oxidizer; in a normal room on Earth, that oxidizer is usually oxygen.

Chemical combustion ("flame") can also exist in an atmosphere of chlorine or fluorine; or in appropriate mixtures of perchlorate, and so on. In yet another case of chemistry that is more difficult than the version we learned in high school, sulfur can burn hydrogen under certain conditions; sulfur acts as a weird simultaneous "fuel-and-oxidizer" in that reaction. If you mix hydrogen and sulfur dioxide, sulfur will even un-oxidize from the oxygen and re-oxidize with the hydrogen; under other conditions, the reaction goes the other direction[7]. All of those chemicals will "burn" hydrogen in a chemical reaction. A 100.0% hydrogen atmosphere, however, can not sustain a flame.

If you want to start mincing words, we can also redefine the plain english word, "burn", to encompass the totally-different physics and nuclear chemistry called hydrogen fusion. This is actually a commonplace abuse of language among people who study stars, for example: if you read our article on Stellar nucleosynthesis, you see the word "burn" used throughout the article.

Nimur (talk) 19:43, 14 September 2017 (UTC)

Well they were both faster than me, so I'll just say Nimur and Shoy are right (well, Nimur might be right or wrong about specialty matches, I don't know). But while we're all here, anyone know why the the table at Flammability limit#Examples has different values for UFL and UEL for hydrogen? I noticed it while preparing my now-superfluous reply. UEL=58%, UFL=75%. The source has the same thing: [8]. None of the other materials have different values (some have ranges). And the way I use UFL and UEL in real life (admittedly not pure chemistry, and not with hydrogen) they're defined identically. --Floquenbeam (talk) 19:48, 14 September 2017 (UTC)

My understanding is that flammable limit is "sustain combustion" where as explosive limit is "deflagrate/detonate". The distinction is probably not that important if your only goal is keeping things safe. shoy (reactions) 15:04, 15 September 2017 (UTC)

At the risk of sounding like a commercial endorsement, these matches burn underwater (and in sand). To scale back my earlier claim, these matches are specialty-items and are not commonplace.

These matches are a real-world example proving that some flames cannot be extinguished. Such materiel embeds the oxidizing chemical into the fuel and once ignited, the fire cannot be extinguished because it self-completes the fire-triangle. Nimur (talk) 19:56, 14 September 2017 (UTC)

Cannot? I bet you could so it if you had a sufficient supply of liquid helium and a way to pump it onto the flame. Just sayin'. --69.159.60.147 (talk) 21:46, 14 September 2017 (UTC)

Okay, if you can cool it fast enough, by blowing inert gas over the fuel/oxidizer mix, you can make the reaction unsustainable. Moving the ambient air might prevent it from incandescing, and the flame might go out. Nimur (talk) 22:02, 14 September 2017 (UTC)

In some cases, you can also disrupt the reaction with things like Halon. 2601:646:8E01:7E0B:3DB7:8D6E:A762:14CC (talk) 09:06, 17 September 2017 (UTC)

I can't get youtube here...do they say what the chemical mixture is? Might be possible to quench the reaction with...radical trap, alternate oxidizer or reducing agent that gets the process out of some self-sustaining chemical pathway, etc. How far can we destabilize via the fourth side of the fire tetrahedron? DMacks (talk) 21:08, 16 September 2017 (UTC)

A safety match should strike and burn in a hydrogen filled room. (A weird thing is that the ignition of a humble safety match is chemically the same as Armstrong's mixture, which is perhaps the most infamously hazardous thing a pyrotechnics wannabe can attempt to make. But the match and striker are physically separated. Wnt (talk) 00:55, 15 September 2017 (UTC)

To be clear, it will strike and burn as along as there is oxidizer remaining on the match. After it runs out of oxidizer, it will go out. shoy (reactions) 14:57, 15 September 2017 (UTC)

Would the heat of the striking cause the oxidizer to react with the hydrogen atmosphere at all? I have a mental image of striking the match, and having both the box and the match burst into flames (assuming that the reaction of oxidizing gas with fuel solid would look similar to the reaction of oxidizing solid with fuel gas... which is also an interesting question). MChesterMC (talk) 15:17, 15 September 2017 (UTC)

Cassini

is there any prediction of what happens when she crashes through Saturn? Treasure trove of data coming in 20+ hours but would be nice for the article to compare what is expected.

also any word on future missions.

Thanks.Lihaas (talk) 20:20, 14 September 2017 (UTC)

JPL has a great website on the event: JPL's Saturn Website main page presently has a special - Cassini: The Grand Finale. Here's an interview with several of the program scientists, including a description of what's about to happen in the next few hours as the spacecraft enters Saturn atmosphere. The spacecraft will begin to aerodynamically tumble, eventually enduring aerodynamic stresses beyond its ability to maintain directional control. The spacecraft will no longer be able to point its antenna toward Earth; and will tumble unpredictably before ultimately breaking apart. Here's a more detailed overview: Cassini Spacecraft Makes Its Final Approach to Saturn.

"Within about 30 seconds following loss of signal, the spacecraft will begin to come apart; within a couple of minutes, all remnants of the spacecraft are expected to be completely consumed in the atmosphere of Saturn."

Here's a long-form documentary, (about 15 minutes long), from earlier this summer; it includes some stunning animations representing what NASA's digital artists think the spacecraft break-apart would look like if you could watch it with your own eyes at Saturn.

It's a little hard to understand intuitively, but the material of the spacecraft will be hitting atmospheric gas, as dense as Earth's sea-level atmosphere, while it's still moving at orbital entry speeds - about 70,000 miles per hour (or about twenty miles each second). At those speeds, the heat of aerothermal friction is so high that even space-grade metals - like titanium - or ceramic or composite structures - just can not withstand the heat and stress. Hitting air molecules at that speed can be as destructive as slamming into a solid object.

This link - JPL's Cassini Grand Finale interactive feature - is a fun tour of the last hours of mission operation, full of cool animations and brief descriptions. The feature explains which parts of the spacecraft are expected to break off first, using language that's accessible to an average science enthusiast.

"Cassini’s gold-colored multi-layer insulation blankets will char and break apart, and then the spacecraft's carbon fiber epoxy structures, such as the 11-foot (3-meter) wide high-gain antenna and the 30-foot (11-meter) long magnetometer boom, will weaken and break apart. Components mounted on the outside of the central body of the spacecraft will then break apart, followed by the leading face of the spacecraft itself."

Nimur (talk) 20:29, 14 September 2017 (UTC)

@Nimur: fascinating, and I am an "average science enthusiast," but I thought that the atmosphere is way stronger than ours?

Further, is there a remote possibility (in probability theory there are no absolute certainties (or vice versa) she can survive to send back more data? I realize even at this point IFF it happens she;;ll [almost] certainly never leave Saturn.Lihaas (talk) 20:55, 14 September 2017 (UTC)

Saturn is an enormous planet. The spacecraft's orbit will take it over the "cloud tops," and as it descends, it will encounter denser atmosphere. The air will get about ten times as thick for each minute the spacecraft falls.

There is no realistic way for this spacecraft to survive the plunge into the planet's atmosphere. It is not structurally designed for reentry; it has no heat shield.

Even if the spacecraft survived, it will begin tumbling as soon as the atmosphere becomes thick enough. Once the spacecraft is tumbling, it cannot point its antenna at Earth, so we can not hear any messages it sends to us. We'll be pointing the most sensitive antennas on our planet - Deep Space Network - using an antenna in California and another in Australia. Even with our most sensitive antennas, we can't detect Cassini's signals after it starts tumbling.

The mission planners know that is going to happen - so they've configured the spacecraft to send as much data as possible before it hits the planet; and to transmit as much as possible on the way in.

No part of the spacecraft will remain intact: it will be evaporated by the intense heat, like a meteor.

Is any other outcome possible?

No.

Several years ago, after I read the Wikipedia article on "almost surely", I had a long and boring conversation with my mathematician friend. We took that article apart piece-by-piece. We did a verbal epsilon-delta proof. We constructed a Lebesgue measure for the probability integral. We took the language apart, constructed a grammar, used axiomatic set theory. We talked about alternative views on the issue, colored by my various backgrounds in physics, in engineering, in philosophy. We talked about using probabilities as inputs to decision problems in game theory. We talked about plain English words, and the very same words used in technical mathematical parlance. We talked about "certainty," and "good-enough-certainty." We came to no new profound understanding.

Almost surely, the spacecraft will break apart.

Nimur (talk) 21:10, 14 September 2017 (UTC)

Quibble regarding "the heat of aerothermal friction" -- my understanding is that friction plays a small part in the heating of a spacecraft (or meteor) on atmospheric entry. The main heating effect is caused by the compression of the air in front of the object. Atmospheric entry says "Direct friction upon the reentry object is not the main cause of shock-layer heating. It is caused mainly from isentropic heating of the air molecules within the compression wave." CodeTalker (talk) 22:17, 14 September 2017 (UTC)

Good observation; I'm lumping all of the aerodynamic heating effects together. Reentry thermodynamics, as you point out, become very complicated. Nimur (talk) 23:06, 14 September 2017 (UTC) −

Any chance bacteria can survive? There are water vapor clouds and comfortable temperatures near the bottom of the observable cloud layers. (The gravity is Earthlike also, so any relevant microbes need to be able to hang aloft for long durations) Wnt (talk) 00:57, 15 September 2017 (UTC)

No, the chance is extremely low. NASA's Planetary Protection Office specifically researches how to prevent biological contamination of worlds we explore, even when we send robotic probes like Cassini.

Here's their brief overview on bioprotection for Saturn's moons.

Nimur (talk) 12:56, 15 September 2017 (UTC)

After we crash our satellite into Saturn, I expect angry Saturnians to fire back at Earth. (Those same Saturnians were also angered by the civilizations on some of their larger moons, and those moons are now rings.)  :-) StuRat (talk) 03:33, 15 September 2017 (UTC)

Actually the Rings of Saturn article says that all the particles together would be a moon a little smaller than Mimas, though it also says that Cassini gave some indications that's a bit of an underestimate. Wnt (talk) 11:33, 15 September 2017 (UTC)

Have Cassini or any other of our probes ever gotten close enough to the rings to get pictures of some individual pieces of them? ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:43, 15 September 2017 (UTC)

Textures in the C Ring; Waves and Small Particles in the A Ring; Moon-Made Rings; A Lone Propeller; Daphnis. Many photos exist from a long and accomplished scientific mission. Some of our useful information about ring material comes from non-photographic data - such large areas can be understood by imaging them with radio and other instruments - but the picture we get is a little different than a photograph. Nimur (talk) 14:27, 15 September 2017 (UTC)

September 15

Extreme(ly foolish) Airbrushing

I want to use a cheap airbrush to spray clothes-washer grade bleach on some clothes dyed using natural colorants. What kind of bleach is a better choice, chlorine-based bleach or peroxide-based bleach?

Chlorine-based bleaches are sold as aqueous solutions. They are very likely easy to spray.

Peroxide-based bleaches are mostly sold as dried powders and must be dissolved in water before use.

I want to "paint" on the clothes using the bleach. I will do it outdoors in the open and wear rubber gloves, eye protective and a breath mask. I just want to know which kind of bleach is relatively friendlier to the airbrush which is made of stainless steel and rubber O-rings. -- Toytoy (talk) 01:34, 15 September 2017 (UTC)

An Airbrush is a tool that needs a supply of compressed air. Will you consider instead a cheap plastic spray bottle? I find that a disposable spray handle screws directly onto a large plastic bottle of chlorine bleach. Blooteuth (talk) 11:05, 15 September 2017 (UTC)

In the 70s, it seemed common to me to use plastic spray bottles with chlorine bleach to fade out our jeans. Then, many people painted on the faded parts. Bleach is "wet", so it doesn't stick to one spot. It bleeds into the fabric. Further, it isn't about how much bleach you use. It is about how long you leave the bleach on the clothes. 209.149.113.5 (talk) 11:22, 15 September 2017 (UTC)

• Either bleach will do this, although the perborate (oxygen) bleaches tend to be better at cleaning without damaging dyes, so you might want to use hypochlorites.

For an airbrush (I use a lot of airbrushes, and I spray awkward things through them) you can't beat the old Badger 250 design [9], which is widely copied and comes from China via eBay for about £10. This is the crudest airbrush around, as an external mix brush with no metering needle. It does though have the ability to spray almost anything and is much less fussy about fluid viscosity. Easy to strip and clean too.

For your sanity, get a quiet airbrush compressor too, not a garage one. Andy Dingley (talk) 11:27, 15 September 2017 (UTC)

I appreciate you're taking precautions but it may not be worth it: [10]. 92.8.176.91 (talk) 12:13, 15 September 2017 (UTC)

Quats aren't bleach. Andy Dingley (talk) 12:25, 15 September 2017 (UTC)

That article is way over my head but this medical report [11] is headed "Regular Use of Bleach Linked to COPD". 92.8.176.91 (talk) 12:49, 15 September 2017 (UTC)

I wouldn't pay much heed to either of those as sources (try running WebMD past WP:MEDRS!) - if someone can post the citation or link for the original paper, that would be appreciated. Andy Dingley (talk) 15:14, 15 September 2017 (UTC)

[[User:Andy Dingley, Point taken, the WebMD article does eventually say "The results should be treated with caution as they have yet to be published in a peer-reviewed journal." Both news articles above are very recent. It seems as though the study is not utter rubbish, but I also don't trust either of those sources to not sensationalize or otherwise muck things up. They do both seem to be reporting on the same thing, though neither can be arsed to even give a name of researcher. It seems to be analyzing data pulled from one of these long-term longitudinal studies of nurses, based on surveys etc. Telegraph mentions Harvard, but Harvard has not yet issued any press release [12] as far as I can see. SemanticMantis (talk) 17:20, 15 September 2017 (UTC)

I think this paper isn't published until Monday, and it's not easily visible. Presumably there's a press release copy already circulating, but I don't read medicine so haven't seen it. The newspaper reports all seem to be conflating disinfectants and bleaches, in a way that has nothing as yet to support it. Andy Dingley (talk) 17:27, 15 September 2017 (UTC)

This comes down to risk/benefit ratio. Splashing about in a chlorinated swimming pool brings one into contact with a very dilute solution of chlorinated phenols, due to the action of sodium hypocrite reacting with organic matter (they often occur in chlorinated tap water as well). Phenols are know to be cancer promoters... but the 'risk' of splashing around in non chlorinated water or drinking it is higher - much higher. My favorite way to avoid chlorinated phenols , is to drink pure spring water only... but even then ! I always take the greatest care ( ask the family) to sanitized it with a equal amounts of a good Scottish Single Malt. So chlorination is not the only solution and in many ways, the old traditional ways are best (IMHO) . Aspro (talk) 15:54, 15 September 2017 (UTC)

How about grain alcohol and pure spring water to replenish your vital bodily fluids ? :-) StuRat (talk) 17:20, 15 September 2017 (UTC)

Grain alcohol ? Rather wash my mouth out with soap.Aspro (talk) 12:51, 16 September 2017 (UTC)

I think he's more concerned about keeping his Essences Pure. In which case, he'd be well served to learn what "spring water" is, and how it's different from mineral water. Andy Dingley (talk) 17:28, 15 September 2017 (UTC)

As always, AD is pedantically on the button by pointing out that Spring & Mineral are not always considered interchangeable. However, “Spring water can be considered mineral water if it naturally contains the required amount of trace minerals.” Mineral Water Vs. Spring Water. Which is a comparison that I would agree with, providing both contain the minerals. Unfortunately, many a good water now comes in plastic bottles which can leach phthalates over time. These chemicals can cause frogs etc., to exhibit both male and female characteristics, which why phthalates have been nicknamed gender-benders. Fortunately, Haggis survive by just licking the morning dew. Which is presumably why, I haven’t seen any that have ram like attributes and the growing of horns– but I constantly live in fear of what people on vacation may feed them. The left-overs from a McDonald’s family meal is not a haggis's normal diet. Lastly, who granted McDonald's the right to use the clan name of McDonald and trademark it ? Clan Chief McDonald didn't – he said so! Anyway AD, you're leading us off at a tangent to the OP's question. Also, I don't think I would be better served, if even if I had my own sommelier ;¬) Aspro (talk) 12:51, 16 September 2017 (UTC)

Your neighbors might complain about bleach fumes. I suggest you consider hydrogen peroxide. It's inexpensive enough and far less toxic. It also flows quite well. It may have less bleaching power, depending on the strength. At high concentrations, it's flammable and even explosive, but you won't find that concentration available in stores, where 3% is typical, and that 97% water will keep it non-flammable. If that doesn't bleach enough, you can find somewhat higher concentrations sold online. StuRat (talk) 13:34, 15 September 2017 (UTC)

The OP hasn’t mentioned the nature of the stains. Bleaches of any variety are not always efficacious, especially with natural dyed fabrics. Other cheap alternatives are often better [13], [14] Also, cheaper than an air brush but just as effective in this application is one of the many Spray Atomizer Bottles at around £1 to £2. Example : [15]. Aspro (talk) 14:27, 15 September 2017 (UTC)

I don't believe the OP wants to clean the clothes, but rather create something like a tie-dyed look by randomly bleaching out the color in spots. StuRat (talk) 17:22, 15 September 2017 (UTC)

Maybe this article could be expanded? Apart from the dangers of swimming pools, here's a detailed study on the dangers of domestic cleaning chemicals: [16]. 92.8.216.51 (talk) 16:25, 15 September 2017 (UTC)

Tileable "scatter" patterns for texture generation in a CGI context.

Hi,

This is on the Science Desk but is here rather than the Mathematics desk because it relates to image generation. In the context of a simulation and CGI generation suite, it is possible to generate textures to represent fine details that cannot for various reasons be implemented as geometry.

Does anyone have a reference to a paper or article (most likely a SIGGRAPH report) that gives a method for generating seamless texture artwork approximating a field of vegetation or crop when viewed from above or moderate distance, utilizing random scatter patterns based on an observed colour distribution over a number of sampled images from the real world? ShakespeareFan00 (talk) 12:32, 15 September 2017 (UTC)

Think you may have better luck asking this on a Wikimedia Commons help desk, whose editors are more into images. There are applications like MegaScatter but I don't know if this is what you mean. Aspro (talk) 15:06, 15 September 2017 (UTC)

Well I found sort of the converse: using hierachical Bayesian methods to analyze textures in photographs of weeds and crops [17]. Might give you some insight on how to generate such a thing. SemanticMantis (talk) 16:40, 15 September 2017 (UTC)

Oh, here you go, this is much close I think: [18] [19] Use google scholar to track down other work by Deussen, the common author on those papers, also you can use Scholar to skim through later works that cite these. Thanks for the interesting question, I knew a bit about this stuff but I'm pretty blown away by some of the figures in those papers SemanticMantis (talk) 16:46, 15 September 2017 (UTC)

Space probe selfies

In a similar refdesk question some time ago someone answered that artistic renditions of space probes are because it's impossible to take a photo of them on a mission in deep space (e.g. for Cassini-Huygens, etc.). So what's the problem with installing an additional camera on them for selfies or shooting with an already existing onboard camera, like it was done for selfies from Curiosity Mars rover? 212.180.235.46 (talk) 16:39, 15 September 2017 (UTC)

Certainly possible, but anything you put on a space probe costs millions of dollars, and/or replaces some valuable instrument(s). It's hard to justify spending taxpayer money to do that, just for selfies. I suppose there could be an argument made for it, that it would allow them to spot potential problems like a micrometeorite hit, but the chance that a problem could actually be spotted and then fixed in this way is next to zero. StuRat (talk) 17:12, 15 September 2017 (UTC)

Basically because putting a camera on an arm wouldn't have any practical use for a deep space probe.

The mast camera on Curiosity is on the end of a flexible arm because they want to be able to get closeups of rocks and stuff. The fact that they could use the camera to create cool looking selfies didn't even occur to them until it was already on its way to Mars.

Here's a great article on the Curiosity Selfies : The story behind Curiosity's self-portraits on Mars (I like the selfie taken by the duplicate robot sitting in a robotics lab at JPL.)

On a deep space probe there wouldn't really be a point to putting a camera on the end of a long, flexible arm. It never gets close enough to anything that an arm would be useful. If they want to take a picture of something, they turn the whole probe to face that thing. A long arm would just something that could break, and unneeded weight.

Maybe they'll do it some day, if only if they need the hardware for some other thing. I can't find the reference right now, but I believe there are some proposed space telescopes that consist of more than one craft flying in formation. If they build them, maybe those things will photograph each-other. ApLundell (talk) 17:25, 15 September 2017 (UTC)

• The additional mass is by far the most important disadvantage of adding "selfie" hardware. The incremental cost, power, and complexity (i.e, unreliablity) are also important, but extra mass is a show-stopper. This is especially true for deep-space probes. That mass would be traded against electrical power, or thruster fuel, or antenna size, or initial launcher capacity, or some other critical mission constraint. -Arch dude (talk) 04:12, 16 September 2017 (UTC)

In addition to the obvious - that it would serve no real purpose - keep in mind that Cassini launched in 1997, and according to EO, the term "selfie" didn't become a "thing" until at least 2002.[20] In practicality, selfies have been around a lot longer, they just hadn't coined the term yet. But in 1997, it was not really on the radar. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:29, 16 September 2017 (UTC)

The "Problem" may be that these are no tourist trips but scientific missions. Nevertheless in general- whats the value in a "selfie"? Visual prove of an potential epic meeting? Are close range detailed images of Saturn, without any obstacles, not most epic already? --Kharon (talk) 06:48, 16 September 2017 (UTC)

Rosetta at Mars, perhaps the only deep-space selfie

In the days of film cameras, I used to hear the term "proof of visitation", such as standing in front of the Eiffel Tower just to prove that you were there. The advent of digital technology has probably rendered that concept obsolete, since anyone can easily artificially put themselves into any picture. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:52, 16 September 2017 (UTC)

• It's not entirely impossible. Cassini carried the Huygens probe with it - in theory, one could have photographed the other as they separated. As it happens, the cameras weren't facing the right way, but Rosetta was able to take a selfie by activating Philae's camera while the two were still connected, and it repaid the favour when Philae separated. Note that the photos aren't great quality - lighting in space is very stark, and spacecraft cameras are usually calibrated to photograph very large, distant objects, not small, close ones (even getting the dark image of a solar panel took a lot of photo editing and edge detection work, to pick out the details in the gloom). Smurrayinchester 11:55, 16 September 2017 (UTC)

Effects of painful stimulus on food intake in rats/mice

I'm interested in any experiments done on rats/mice relating to whether applying a painful stimulus to receive food reduced food intake in the test subject. For example, even with an abundance of available food will the subject eat less if it receives a painful stimulus upon approaching / eating the food? Does the subject eventually get used to the pain and resume normal eating patterns? Are there any such scientific studies that you could link me to? Thanks for your time. — Preceding unsigned comment added by 119.42.87.140 (talk) 19:14, 15 September 2017 (UTC)

At a more practical level barbed wire or electric fences work. Greglocock (talk) 20:36, 15 September 2017 (UTC)

Read this article. --Jayron32 20:43, 15 September 2017 (UTC)

The type of conditioning you're looking for is called Positive punishment. (In humans, if it's being done by a doctor it might be called Aversion Therapy.)

The wikipedia articles don't answer your precise question, but maybe they'll help in your research. ApLundell (talk) 21:35, 15 September 2017 (UTC)

This article notes decreased appetite and weight loss as signs of dental problems In Rodents. Blooteuth (talk) 22:48, 15 September 2017 (UTC)

• What you are asking about are approach-avoidance conflicts -- however the science on this is pretty complex and our article is not very informative. The bottom line is that, yes, the punishment will probably reduce eating, but a lot of factors come into play, most importantly the strength of the punishment. Looie496 (talk) 02:48, 16 September 2017 (UTC)

Cold-water immersion and heart rate

Does spending time on cold water (full body) reduce average heart rate? I mean not only when we are in water but during the day, in the same way that aerobic exercise reduces our resting heart rate? — Preceding unsigned comment added by 31.4.136.173 (talk) 21:59, 15 September 2017 (UTC)

See the article Hypothermia that describes the effects of reducing the Human body temperature below 35°C. Therapeutic hypothermia is a medical treatment occasionally applied to reduce the risk of tissue injury following lack of blood flow. Hypothermia has possible adverse effects and no proven subsequent benefit. Blooteuth (talk) 22:32, 15 September 2017 (UTC)

I assume the OP means something along the lines of ice baths or the polar bear plunge and not reducing your body temperature up to a potentially lethal level.--B8-tome (talk) 23:45, 15 September 2017 (UTC)

See here. Count Iblis (talk) 01:44, 16 September 2017 (UTC)

September 16

Lesch–Nyhan syndrome

Lesch–Nyhan syndrome causes a mess of problems: the patient cannot produce a specific enzyme, produces too much uric acid, experiences intellectual disability severe enough to prevent speech and ambulation, and is susceptible to a raftload of self-harming behaviors. I get the impression that the enzyme absence causes the overproduction of uric acid somehow, but what causes the rest? The article seems to suggest that the hyperuricemia is responsible for everything, yet that seems unlikely (why would too much of a toxic acid cause compulsive self-harming?) — but then I've looked over the "Pathophysiology" section without understanding much of anything after the first three paragraphs. Nyttend (talk) 03:35, 16 September 2017 (UTC)

From the article: "The etiology of the neurological abnormalities remains unknown." Ruslik_Zero 08:13, 16 September 2017 (UTC)

Nonetheless, it might be useful to research purine autism, which also involves hyperuricemia. Purine autism is interesting in that it is a kind of autism said to respond to allopurinol treatment, though I would have expected much more confirmation of that by now if it were reliable. [21] Note that autism can also cause self-harm activity and is mentioned in this regard in our Lesch-Nyhan article. Wnt (talk) 11:32, 16 September 2017 (UTC)

Hm, I didn't realise that "etiology" meant "origin" or "cause". Nyttend (talk) 12:33, 16 September 2017 (UTC)

Aquo complex versus hydrated compound

Is there a clear demarcation between an aquo complex and a hydrated compound; or does it simp.ly depend on context; or does it depend on the particular author? I am not talking about water of crystallization when I say 'hydrated compound'. Case in point: tetraaquocopper(2+) sulfate versus copper(2+) sulfate tetrahydrate. Does it have anything to do with the degree of lability of the aquo ligands, or perhaps whether the complex is homoleptic? Plasmic Physics (talk) 07:03, 16 September 2017 (UTC)

At the level of one of my freshman chemistry textbooks (General Chemistry by Ralph H. Petrucci 5th edition 1985, p.911) and this website [22] (Washington University at St. Louis), both would appear to be non-standard names for coordination complexes, although the first is close. Standard nomenclature would be tetraaquacopper(II) sulfate, indicating copper 2+ coordinated to 4 waters and not coordinated to the sulfate counter ion. "Copper(2+) sulfate tetrahydrate" would mean CuSO4.4H2O to me, which would be an example of water of crystallization. An example of where you have seen this would be helpful, but using CuSO4.4H2O terminology would be necessary in instructions for a copper sulfate solution preparation to get the right mass of starting reagent for the desired concentration of copper sulfate.--Wikimedes (talk) 17:45, 16 September 2017 (UTC)

Using the ionic charge instead of the oxidation state when constructing additive names seems to be the preffered alternative convention according to the latest IUPAC nomenclature conventions. From what I've read, when 'hydrate' appears in the name, it can refer to either an aquo complex or w.o.c. introducing vagueness. From your your concluding remark, I gather that which one to choose, depends more on the context? If that is the case, what defines the context in which either use would be appropriate? Plasmic Physics (talk) 23:28, 16 September 2017 (UTC)

Standard nomenclature seems unambiguous, and you probably can't go wrong by choosing the standard way of saying or writing things. (2+ vs. II or aquo vs. aqua wouldn't impede understanding and is just a tangential nitpick.) One of my fields is solid state chemistry; I'm not up on common variations of standard nomenclature in coordination chemistry and can't recall much anecdotally.--Wikimedes (talk) 02:29, 17 September 2017 (UTC)

(My appologies, it appears it is actually supposed to be 'aqua'). Solid-state chemistry? Interesting... How can you tell expermentally or theorhetically, if an atom is bound to a neighbouring atom in a bulk phase? Plasmic Physics (talk) 03:03, 17 September 2017 (UTC)

Breaking boards

How much force does it take to perform a power break on an unpegged stack of 4 standard 1-inch-thick boards made from seasoned pine, dimensions 12x6 inches, grain along the 6-inch edge? How much more force is needed if the stack is increased to 6 boards with all the other parameters remaining the same? (This is NOT homework -- this is me trying to gauge my own strength!) 2601:646:8E01:7E0B:3DB7:8D6E:A762:14CC (talk) 08:02, 16 September 2017 (UTC)

You don't break them with force (at least, not in karate), you use impulse to do it. This is the product of force and time (strictly, their integral). There are two impulses under consideration here, the impulse given to the moving hand by the body, and the impulse the moving hand then transfers to the boards. Much of karate training is about increasing the impulse given to the hand, in the short time available. Considering human muscle generally, we're "strong but slow" - a mediocre performer in pure strength sports can produce more force than most karetaka can, but they can't deliver anything like the same impulse. The ultimate demonstration of this being of course the "inch punch" techniques.

This also indicates why an empty hand technique is limited (for pure striking effect) against anything with a weighted glove, or a kick (legs are heavier than arms). Human muscles are better at loading impulse into things slightly heavier than a single hand.

Then there's the matter of transferring the impulse into the board. It takes a certain amount of energy to fracture a brittle material like dry cross-grain timber, so six boards will need at least $6/4$ as much as four. But, one must also couple the impulse of the hand effectively into the boards. This is very difficult to model as a physical process, because it's fast and the materials (mostly hands) are flexible, so they turn the energy of the moving hand into compressed and displaced flesh, rather than bending (and breaking) the board. This is the second matter of karate training: which part to strike with and how to keep the hand rigid enough.

Then there's the physics of breaking boards. The easiest boards to break are a stack of moderately thin boards, already touching at the impact point. It is hard to break the same boards with spacers at their edges. If they're spaced apart for visibility, they sometimes have a 'coupler' in the middle too. It's very hard - soon impossible - to break a single board of the same thickness. Also don't demonstrate against a carpenter who gets to choose which boards to use, because there's visible and selectable variations in their strength. Boards are broken by exceeding their strain, not their stress. It's not applying a force greater than their ability to resist, it's bending the board past their linear ability to extend (why the materials broken are chosen for being brittle, i.e. having a poor resistance to strain, even if strong against a stressing force). If the boards are too thick, you can't bend them enough to achieve this strain - you may put a Herculean dent into the top, but they don't snap. If they're too thin, they become simply flexible and all you will do is bend them down and have them spring back afterwards - this is some of the theory behind composite materials. If the boards are in a spaced stack, then there is considerable bending in the upper boards (absorbing your impulse), but there isn't enough left for the lower boards to break them. Bending the upper boards downwards to touch the next board absorbs energy and this energy is lost to the strike when the board breaks (it turns into sound or an acceleration of the board halves starting to move independently). So a spaced stack of boards will require an impulse that increases more than the number of boards. Exactly how much more is tricky to work out, as it depends on many factors - such as the relative energy needed to bend a board down vs. the energy to break it. A stiff board in a spaced stack (such as tiles) is very hard to break.

Boards and tiles are broken for demonstrations because they demonstrate the effect of impulse over force. To show simple force strength (and not highlight the effects of speed), then punching a swinging bag and seeing how far it moved would show this better - and the karetaka would probably lose to Indian wrestlers. Andy Dingley (talk) 09:39, 16 September 2017 (UTC)

@Andy Dingley: I am suspicious you are thinking of something else besides impulse here. The impulse is force x time, and causes an acceleration of the target object. In other words, the swinging bag would be a perfect measurement of impulse. What you are describing seems more like simple speed, or perhaps some other quality, that allows the board to be pulled far off center before it has much of a chance to push back on the hand i.e. to apply its impulse to the hand. But I know nothing of how to break multiple boards with a hand, so I am likely wrong. Wnt (talk) 11:39, 16 September 2017 (UTC)

Would it be rate of transfer of impulse (= rate of change of momentum) that is important here? Dbfirs 12:05, 16 September 2017 (UTC)

And if so, that would be the force! (F*t)/t=F 2601:646:8E01:7E0B:3DB7:8D6E:A762:14CC (talk) 12:17, 16 September 2017 (UTC)

So it would! I've never tried to break boards (at least not seriously). Presumably, one needs both a large impulse and a fast rate of transfer (speed of strike; force) to achieve the effect. There is some discussion here but I'm not convinced by the approximations in the mathematics. Dbfirs 12:27, 16 September 2017 (UTC)

The link loops back to Wikipedia: Breaking (martial arts) for a source. Our article there has some data (also shows some signs of personal stress, like the uppercase link to SCIENCE). I am still not convinced it is very simple. For one thing, the displacement of the board depends on the force, but force is a tricky thing. Suppose you contrast my hand, modelled by a heavy sausage wrapped in confectionary marshmallow, versus the hand of a martial artist, modelled by the sausage wrapped in horn. Well, if I had a rocket booster handy to get my hand up to the same speed as the artist, the impulse would be the same. But the force wouldn't be the same because the whole mass of the marshmallow has to squish up (OUCH!) before all the momentum is transferred; but the horny hand of the artist presumably is more rigid and conducts that impulse rapidly upon the first few millimeters of contact (and impulse/time = force). Bent off center more rapidly by the increased force, perhaps the board breaks sooner, and therefore has much less time to transfer impulse back to the hand of the artist. So how much is speed, needed to build up the hand's impulse, and how much is rigidity, to deliver it? And what else have I forgotten? Wnt (talk) 18:07, 16 September 2017 (UTC)

Shortest Nobel Prize-winning paper

Today I learned that Watson & Crick's paper announcing their discovery (or at least, their part in the discovery) of the structure of DNA is a mere 834 words - exceptional brevity for such a significant finding. Is that a record? I appreciate Nobel Prizes aren't for papers but for research generally, but using published papers which described Nobel-winning research as a metric has anyone ever bettered 834 words? 51.9.138.245 (talk) 10:10, 16 September 2017 (UTC)

Watson & Crick's paper was so short largely because they were in such a hurry. Much of the background work was already known. Pauling had already published one postulated structure, which was largely held to be unworkable. They thought that others (i.e. Pauling) would reach their own conclusions for themselves if given much more time. Watson & Crick had two ideas, the double helix (rather than a triple structure) and also the "zipper" idea for replication. They wanted to be Wallace, not Darwin. Their paper wasn't publishing the results of long years of research and careful study (that was mostly out there already, or was filled out later) it was throwing two wild ideas out to claim clear priority on them, even if they turned out to be wrong later. The specific paper is a brilliant hypothesis, not careful research. Andy Dingley (talk) 10:36, 16 September 2017 (UTC)

• Since Watson and Crick were mentioned, Rosalind Franklin must be mentioned too. Fgf10 (talk) 11:39, 16 September 2017 (UTC)

One of the justifications for Franklin not being mentioned on this paper has been that the paper was based on the two "wild guesses" that were so urgent to make publicly visible and so to claim precedence for. Franklin's work had been the painstaking careful research that led up to this. Sadly and IMHO wrongly, the Nobel Prize was awarded for the narrow paper, and overlooked Franklin's contribution to making it possible to have those ideas. Andy Dingley (talk) 12:42, 16 September 2017 (UTC)

I fully agree that Franklin should have been given more credit by the scientific establishment, but it's difficult to see how the Nobel Committee itself could have: Nobel Prizes are never awarded posthumously, and Franklin had died in 1958, 4 years before the award to Watson, Crick and Maurice Wilkins. Watson himself suggested that, had she lived, she might also have shared the award.

Perhaps those three should themselves have made more of her contribution, which Franklin may never have been fully aware of, as Wilkins had shown her critical 1952 photo to W & C in 1953 without her knowledge, and after she herself had moved on to a different college and different areas of research. {The poster formerly known as 87.81.230.195} 90.200.137.12 (talk) 16:06, 16 September 2017 (UTC)

Well her also sharing the award with Watson, Crick and Wilkins, if she had lived was surely about as likely as her getting the award after she died, i.e. really unlikely. Prize rules limiting a single prize to 3 people would have required either there were 2 awards in two separate categories or years, or there was something weird like the Randall X-ray diffraction lab. Mind you, I'm not sure anything but the Nobel Peace Price can be award to an organisation. Our article suggests so but the cited source doesn't really seem to say this and the closest I can find on the Nobel site is that in some places they mention the Nobel Peace Price has been awarded to organisations etc. Anyway, if they had wanted to award to an organisation in memory of her, I don't see that her death really stopped that. And if they were going to award 2 prizes, they could have simply said no living person deserved the second, although that may seem a little weird since more likely no living person and Wilkins should share the second prize. Mind you the no 3 people and posthumous rules [23] don't really seem to come from Nobel's will anyway [24]. Also although that clearly says the award is divided equally, among the recipients, [25] suggests it isn't always. I guess most likely this arises when 2 separate works receive an award, in which case the one work with 2 recipients gets 1/2 share which is divided among the 2 people, and the other gets 1/2 share which goes to that single awardeee. Nil Einne (talk) 17:48, 16 September 2017 (UTC)

Conway famously published a paper with the title "can n^2+1 unit equilateral triangles cover an equilateral triangle of side > n, say n + e" with the substantive body of "n^2 + 2 can" accompanied by two diagrams. — Preceding unsigned comment added by 2A01:E34:EF5E:4640:35DC:A78A:A81D:9CA4 (talk) 15:32, 16 September 2017 (UTC)

Infinity

Jean-marie Adragna Vancouver B.C Canada

Everybody thing at the infinity at the space in expansion. For my the description of the Infinity is the ( The wave of the Big-Bang forever increase ) Sorry but I don't have any background in science ,i this possible the somebody told me if is possible For my ( fiery ). Sin cerement J-M.A — Preceding unsigned comment added by 70.79.181.150 (talk) 14:57, 16 September 2017 (UTC)

Yes, there are many infinities. There's infinitely large, infinitely small, infinitely forward in time, and infinitely backwards in time, for example. You might also be interested in the infinite worlds hypothesis. StuRat (talk) 15:06, 16 September 2017 (UTC)

Some people regard "infinitely small" as a contradiction in terms. The usual term is Infinitesimal. Mathematically, there is a hierarchy of infinities (see Stu's link above). For example, there are more real numbers than there are whole numbers, but the number of fractions is the same as the number of whole numbers. Dbfirs 16:40, 16 September 2017 (UTC)

But no matter how you slice it, "infinity" is not a quantity, it is not a number. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:33, 16 September 2017 (UTC)

It's actually a cardinality. Dbfirs 19:36, 16 September 2017 (UTC)

Yes, there are different "cardinalities" of infinity. Hence the terms "countably" infinite vs. "uncountably" infinite. But infinity is infinity. As Carl Sagan said, no matter how large a number you can imagine, you are no closer to infinity than is the number 1. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:58, 17 September 2017 (UTC)

Did you read the article on cardinality? Dbfirs 06:25, 17 September 2017 (UTC)cardinality

The term "infinitesimal", which is used to mean "infinitely small", is essentially a way of saying "infiniteth", as compared with "tenth" or "hundredth" or "thousandth".[26] ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:07, 17 September 2017 (UTC)

See also our Shape of the universe#Infinite or finite. -- ToE 17:46, 16 September 2017 (UTC)

See also here. Count Iblis (talk) 22:33, 16 September 2017 (UTC)

Nothing is infinite (with one exception). Everything is by design or definition infact finite as a concept of science. The only exeption is the literal Nothing in Sense of empty space which is the only "thing" that can be regarded as infinite without braking our laws of physics. --Kharon (talk) 03:21, 17 September 2017 (UTC)

Or breaking. But braking works too. :) And if space is "finite but unbounded" then your premise remains true. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:00, 17 September 2017 (UTC)

The metric expansion of space should be braking, but isn't, so the Americans are apparently the only ones to put the brakes on something metric. :-) StuRat (talk) 04:29, 17 September 2017 (UTC)

What does D. Œ. A. V. stand for?

In working on the history of glaciology, I'm finding references to "D. Œ. A. V.", such as this: "Le succès des sondages de 1899 encourageant les plus grands espoirs pour la réussite du levé complet par la même voie, d'un profil transversal du glacier, le Comité central du D. Œ. A. V., qui avait subventionné les premiers travaux, consentit avec la plus louable munificence à faire les frais d'une nouvelle campagne de sondages dans ce but." which Google translates as "The success of the surveys of 1899, which encouraged the greatest hopes for the success of the complete survey by the same route, of a transverse profile of the glacier, the central committee of the D. Œ. A. V., which had subsidized the first works, consented with the most laudable munificence to pay the cost of a new survey campaign for this purpose." I also see this abbreviation in some old citations. Can anyone tell me what it stands for? The "Œ" quite probably stands for "Österreich" or some variation, since we're talking about the Alps; the A might derive from the Alps. Googling the abbreviation and searching Google Scholar for the cited papers hasn't gotten me anywhere. Any other way to find out? Mike Christie (talk - contribs - library) 16:24, 16 September 2017 (UTC)

Possibly Deutscher und Österreichischer Alpenverein. Cheers ✦ _hugarheimur 16:46, 16 September 2017 (UTC)

That's sure to be it. Thank you very much! Mike Christie (talk - contribs - library) 16:50, 16 September 2017 (UTC)

Atmospheric pressure

My Thermodynamics professor drew a free-body diagram for a lid being lifted by boiling water in the pot below. Applying downward force is gravity and atmospheric pressure, he said, while vapor pressure provides the lift. But doesn't the air inside the pot provide a lift as well due to an equal amount of atmospheric pressure as the air above? Thank you. Imagine Reason (talk) 16:49, 16 September 2017 (UTC)

It could be that your professor is assuming that water vapor has displaced all the air in the pot. Your professor is the best authority on the assumptions s\he has made in his/her model; this would be a good question to ask him/her.--Wikimedes (talk) 17:05, 16 September 2017 (UTC)

Until the lid is lifted, the gas underneath it should be at atmospheric pressure plus the water vapor pressure. So yes, the atmospheric pressure on both sides of the lid cancels out. StuRat (talk) 17:13, 16 September 2017 (UTC)

Since the sides of the pot are not involved in the scenario, should I assume that the lid has been lifted? In that case, will the vapor have completely displaced all the air? Thank you. Imagine Reason (talk) 23:13, 16 September 2017 (UTC)

After a little more thought, I see it this way: If the water is boiling, it means that the gas above the water in the pot is at (or less than) the vapor pressure of water for the temperature of the water. On the stove top, heat is put in until the water temperature rises to the point where this pressure starts to push off the lid. This upward pressure is equal to the downward pressure on the lid caused by gravity acting on the lid and the external gas pressure on the lid, which is atmospheric pressure.

Another way to look at it is that the gas inside the pot is isolated from the atmosphere outside the pot (and the weight of the ~100km column of air that causes atmospheric pressure), so there's no reason to expect atmospheric pressure to be a factor inside the pot.--Wikimedes (talk) 00:42, 17 September 2017 (UTC)

The Temperature vs. specific entropy diagram of Steam

The air is not displaced. Infact it will not be displaced but to the contrary remain and get saturated (with steam) in dependence of its temperature and pressure, in an multicomponent (Water and Air (Nitrogen, Oxygen Argon Carbon dioxide etc.)) Vapor–liquid equilibrium commonly named and known as "Steam" (See Steam T-s-diagram in added picture on the right). --Kharon (talk) 03:00, 17 September 2017 (UTC)

• Ask the professor, but a possible simplification would start with the lid directly atop the water with no air under it, and with no air dissolved in the water. As it happens, in real life before boiling starts there will be air under the lid and air dissolved in the water, but the total amount of air is small in proportion to the amount of steam that is generated, so its effect is mathematically negligible in a sufficiently large container.-Arch dude (talk) 04:03, 17 September 2017 (UTC)

I don't want to ask the professor because he introduced concepts like gage pressure without much explanation and refused to answer a student who asked about it. He didn't mention anything about cooking a vacuum. Also, if the atmospheric pressure from the air inside the pot is negligible, then so is the atm outside, no? Imagine Reason (talk) 04:46, 17 September 2017 (UTC)

You are at the start of thermodynamic lessons obviously, else you had not asked your question. It will be answered later on. You will learn to use the Gas constant, learn about Bernoulli's principle etc. Your professor probably tried to tease you to get you interested and wanting to learn. You still have to learn, to understand, which obviously seems much more boring then trying to bend your mind around it with what you already believe to understand. Have some patience, do your lessons and you answer this question and other new ones yourself. --Kharon (talk) 05:40, 17 September 2017 (UTC)

If the atmospheric pressure from the air inside the pot is negligible, then the atmospheric pressure from the outside should be neglected as well, no?

Feynman Lectures. Exercises. Exercise 14-15 JPG

. .

...

14-15. A certain spring has a force constant k. If it is stretched to a new equilibrium length within its linear range, by a constant force F, show that it has the same force constant for displacements form the new equilibrium position.

—  R. B. Leighton , Feynman Lectures on Physics. Exercises

In Solutions they write: Let the spring is stretched by the force F₀. The displacement can be found from F₀ = k x₀. Let's stretch the spring more by x. Then new force is : k(x₀ + x) = k x₀ + kx = F₀ + kx. So extra force is the same as if the spring is stretched from undisturbed state.

But the Solution' author uses k=const from beginning of the proof. If k is some function of x, and F = k(x)•x only for very small x, then how to prove the exercise? In other words, we have the undisturbed spring length L₁ and we know the law for it: F_I = k₁ x for small x. And we have the stretched spring length L₂ and the law F_II = k₂ x for small x. From these two laws it is clear that F≠k₂(L₂ - L₁)≠k₁(L₂ - L₁). Username160611000000 (talk) 19:02, 16 September 2017 (UTC)

If a spring has a force constant, then k should be a constant.

It is ridiculous that we are asked to prove k = const, and this is given under the statement of the problem. No, I think we should not use k = const. Besides the exercise is to Lectures 13,14 "Work and Potential Energy".Username160611000000 (talk) 08:14, 17 September 2017 (UTC)

I think you're being asked to prove the constant is constant from the new position. Yes, it's pretty elementary, I mean, k(x+dx) - kx = kdx or something. They can't all be stumpers. Wnt (talk) 18:15, 17 September 2017 (UTC)

If k increases in the spring stretched under force, it seems apparent the new k will be the "force constant" for very small deviations, if the function derivative is continuous. i.e. FII = k2(x +- delta x) for small delta x. Wnt (talk) 19:35, 16 September 2017 (UTC)

It is not impossible, e.g. k = sin (x). Then for x = 0.5π, 1.5π etc. the derivative = 0 and so k(x) = k(x+dx).Username160611000000 (talk) 08:14, 17 September 2017 (UTC)

yeah, but ... if k = 0 at 1.5 m, how is the pendulum going to stay there when it's under some continuous force? Also, this isn't really an exception = for this FII = 0 (x +- delta x). For small deviations it's not a spring, but it's not an exception. Wnt (talk) 09:34, 17 September 2017 (UTC)

ancient glacial features

It's easy to point to valleys that were shaped by glaciers in the last million years. But what are the oldest known glacial features? Are there glacial valleys in continents that were near the poles in Mesozoic times? —Tamfang (talk) 20:35, 16 September 2017 (UTC)

Note that land didn't need to be near the poles to have glaciers. Glaciers covered much of Europe and North America in the most recent ice age, for example. StuRat (talk) 20:53, 16 September 2017 (UTC)

See here. Count Iblis (talk) 21:17, 16 September 2017 (UTC)

Global glaciations and atmospheric change at ca. 2.3 Ga. Count Iblis (talk) 22:14, 16 September 2017 (UTC)

As others have noted about, we have seen signs of ancient glaciations going back billions of years. That said, features like carved valleys will be eroded and changed over time. Given 10-20 million years or so, most features won't be easily recognizable as glacier derived except by detailed study from experts. Dragons flight (talk) 09:11, 17 September 2017 (UTC)

September 17

Vaccination boosters

Why are adults, other than those at high risk, not offered a booster for the chickenpox vaccination if the dose given at childhood doesn't last a lifetime? 90.198.254.50 (talk) 09:08, 17 September 2017 (UTC)

You didn't say where but I see from your ip it is the UK. My guess is because the NHS is being stretched far too far by austerity and have far more important things to spend their money on. But even if it was offered it probably wouldn't be worth it till people were 60 and their immmune systems started to get weaker and they got more liable to get shingles, there's enough chickenpox around still anyway to keep the immune system primed normally. If we were halfway towards eradicating chickenpox it probably would be worthwhile doing booster shots more generally until it was totally eliminated - but that isn't viewed as any sort of important target at the moment. There have been efforts to eliminate measles but those have been stymied by stupidity and ignorance in the developed world in refusing the MMR vacine. Dmcq (talk) 12:30, 17 September 2017 (UTC)

In the case of testing for bowel cancer every patient is written to every two years between the ages of 65 and 70 I believe, and the letters say that those over 70 are welcome to request a self - test pack. So far as I know, testing and vaccination for common diseases is given on request - I wouldn't like the OP to think (s)he can't have a vaccination if (s)he wants one. If you've had shingles once you can get it again, and vaccination does not provide complete protection. 82.14.24.95 (talk) 12:54, 17 September 2017 (UTC)

Is it true to say that "in every disease the entire body is involved"?

I'm reading now a medical book which stays "in every disease the entire body is involved". Now, I am not sure if every disease involves every system in the body. 93.126.88.30 (talk) 15:09, 17 September 2017 (UTC)

Yes, that does seem a bit silly. Acne doesn't normally effect your pancreas, for example. Perhaps they could say "potentially could become involved", as an infection that starts from, say, acne, could eventually spread to, say, the pancreas. StuRat (talk) 15:45, 17 September 2017 (UTC)

• What do you mean by "medical" here? It's clearly starting from the point of holistic medicine, but the woo woo is strong is such fields and the risk is that it can easily diverge into nonsense such as homeopathy. Discussion and rational coverage of such fields is forbidden at WP, and any detailed coverage of them is just blanked with a redirect to a single simple bucket of ridicule, as if all are equally unworthy of consideration. Andy Dingley (talk) 15:55, 17 September 2017 (UTC)

• If I get a severe cold or flu, it certainly "seems like" the entire body is involved, but to turn that experience into some kind of generalized truism seems highly suspect. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:08, 17 September 2017 (UTC)

• The OP needs to cite title, author, edition and page if he wants any sort of real help. And presumably the author has defined his terms and that sentence does not sit alone, but is found within an argument. I wouldn't come here with the sentence from one of my favorite books, "Now it's broken and needs to be fixed", and expect comment if I didn't give the context so that editors could make sense of its significance. μηδείς (talk) 17:46, 17 September 2017 (UTC)

I think the idea is pretty much correct -- at least, if we take "involved" to mean potentially affected during the future course of disease, rather than noticeably damaged. For example, acne might cause dermatillomania, depression, and apparently on some famous occasions can lead to septicemia and even death. Obviously, an intact and well-functioning immune system should keep the acne contained, but then again a truly well-functioning immune system probably ought to have stopped the acne to begin with.

I would anticipate that the moral of the story might be the need for a complete medical history... no matter what. Wnt (talk) 18:11, 17 September 2017 (UTC)

"normally closed" relays

Please could you tell me what consumer electronics are likely to contain "normally closed" relays. I know microwaves contain "normally open" relays which switch to "normally closed" when power is applied. Thanks for your time.