Wikipedia:Reference desk/Archives/Science/2013 February 2

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February 2

0 displacement photon

In a wave the particles do not displace. But according to article photon, EM waves have photons and they displace at speed of 3.0 X 108 m/s. I assume that photons do not travel but only show their energy through vibrations like ordinary matter. So only energy is travelling at the speed of 3.0 X 108 m/s. Therefore the whole universe would be filled with photons and they show different energy intensities by their vibrations just like ordinary matter. I think all should consider this. So do photons actually displace? User:G.Kiruthikan —Preceding undated comment added 11:12, 2 February 2013 (UTC)

Yes, photons move. One complexity of quantum mechanics is that subatomic particles sometimes behave as particles (which do move) and sometimes like waves (which only pass through a relatively static medium). When looking at an individual photon, whose position is known, it's usually considered to be a particle. Only when dealing with light in bulk, or photons with unknown positions, do we tend to view light and photons as waves. See double-slit experiment. StuRat (talk) 16:21, 2 February 2013 (UTC)

I think you are confusing the particle-equivalent of a wave with the medium in which the wave vibrates. In the macroscopic world, we do not usually consider that there is a particle-equivalent, so there is only the medium, which does not displace as you say. But in the quantum world, the particle-equivalent (such as a photon) is entirely separate from the medium (such as an electromagnetic field). --ColinFine (talk) 00:04, 6 February 2013 (UTC)

Grapefruit powder

I regularly buy ruby red grapefruit, but find it often has powder/flakes on the skin which mess up my clothes when I peel it. What is this ? Is it pesticide, a wax added to make it shinier, or some natural coating ? StuRat (talk) 03:56, 2 February 2013 (UTC)

It's almost certainly some kind of food-grade wax, which is ubiquitously applied to commercial fruits to keep them looking pretty on the shelves. This google search: [1] turns up plenty of relevant manufacturers thereof. --Jayron32 04:45, 2 February 2013 (UTC)

OK, assuming it's wax, how can I peel a grapefruit without it making a mess ? StuRat (talk) 05:42, 2 February 2013 (UTC)

Wash it in plain water and a soft scrub brush? --Jayron32 05:56, 2 February 2013 (UTC)

There's also simply yeast which is found on the skin of fruit like grapes. You'd have to post a picture. μηδείς (talk) 05:25, 2 February 2013 (UTC)

If it's wax, warm it with your hands so it becomes pliable, not flaking. Not that we can tell. μηδείς (talk) 05:56, 2 February 2013 (UTC)

That doesn't seem to happen. So, if it's wax, it must have a high melting temperature, as it stays hard at body temp. This is in contrast to the wax applied to cucumbers, which leaves me feeling like I've been "slimed". StuRat (talk) 06:01, 2 February 2013 (UTC)

If it isn't wax, I'm inclined to agree with Medies's idea that this is yeast. Yeast is otherwise completely harmless, it's simply everywhere, and it tends to grow and multiply in places where conditions are right; the outer skin of fruits seems a great medium for yeast: the fact that yeast is so abundant on the outer skins of fruits is what makes applications like wine and cider possible. Now, the acidity of citrus should kill the yeast once exposed to the juice, but the skins aren't that acidic, and its like a decent medium to grow yeast. It bears repeating that such yeast is normal, ubiquitous, and harmless, though if it bothers you running it under tap water for a few seconds and a gentle rub with a rag or brush should take care of it. --Jayron32 06:19, 2 February 2013 (UTC)

OK, I'll try rinsing it off with tap water, then. StuRat (talk) 06:50, 2 February 2013 (UTC)

Most fruit, especially ones with wrinkled or textured skins, should be rinsed/washed. Besides stuff like wax and pesticide residue, bacteria such as E. coli can grow and proliferate. I'm not claiming anything special about the fruit - bacteria can grow practically anywhere - it's just that fruit is often eaten raw and industrial washing is... spotty at best. The situation during harvest may also be quite unhygienic. Matt Deres (talk) 21:45, 2 February 2013 (UTC)

I always wash fruit if I eat the skin, like with grapes, but not when I toss the peels out, as in grapefruit. StuRat (talk) 23:40, 4 February 2013 (UTC)

It could be shellac, which won't melt and will flake. In the US the box has to say what the fruits are coated with, so see if the retailer will let you look at the box. Ariel. (talk) 18:57, 3 February 2013 (UTC)

Sounds likely. How do I remove it without making a mess ? StuRat (talk) 16:52, 6 February 2013 (UTC)

Chemistry question

which of the following contains both ionic and covalent bonds? 1. NaOH 2.HOH 3.C H Cl 4.CO 6 5 2 — Preceding unsigned comment added by 37.228.104.230 (talk) 06:23, 2 February 2013 (UTC)

Please do your own homework.

Welcome to Wikipedia. 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. --Jayron32 06:24, 2 February 2013 (UTC)

Also, what are you trying to list after CO ? The numbers 6 5 2 alone are meaningless to me. StuRat (talk) 06:48, 2 February 2013 (UTC)

Looking at the wikicode, I'm not sure if 652 is supposed to relate to the question. May be some sort of signature or just erroneous typing. Nil Einne (talk) 19:44, 2 February 2013 (UTC)

Well often here on Wikipedia you can find articles on chemical formulae by typing them in. You will find NaOH, HOH perhaps CHCl3 but perhaps your formula is different. CO leads to a disambiguation page, and you would have to pick Carbon monoxide. check your source to see if you have lost digits. (I dont mean toes I mean subscripts as in H₂O. Graeme Bartlett (talk) 09:58, 4 February 2013 (UTC)

Lime burning

Is it possible to make quicklime out of finely powdered calcium carbonate (such as that produced by chemical precipitation)? Or is there a minimum particle size below which it will get blown back out of any existing kiln? I know that a rotary kiln can process fine particles, but how fine is too fine? 24.23.196.85 (talk) 07:22, 2 February 2013 (UTC)

Anybody? 24.23.196.85 (talk) 04:43, 4 February 2013 (UTC)

Well what scale do you want to make it? Do you just want a few grams, a kilo, do you want to make tons or kilotons? Graeme Bartlett (talk) 10:02, 4 February 2013 (UTC)

Industrial scale -- the idea is to use the CaCO3 produced during the regeneration of caustic solution after the latter has been used for extraction of an acidic substance. I'm flowcharting a chemical plant in my spare time, and I want to make it as environmentally clean as possible. 24.23.196.85 (talk) 00:11, 5 February 2013 (UTC)

In quicklime, you'll see that the most common prodction is by thermal decomposition of calcium carbonate, just as you propose. I'm thinking that the key point is whether there is some particle size that is too small to be processed in a rotary kiln. I would think this depends on the design and process settings of the kiln. In principle, there is no minimum size, but once the particles are small enough to be subject to Brownian motion, the process would become impractically slow. If that's the case in your charted plant, you should consider some other way of heating the quicklime, preferably one that doesn't disperse the powder into air.--Wcoole (talk) 21:40, 6 February 2013 (UTC)

Thanks, Wcoole! Does it make a difference if the limestone powder is wet (50-75% moisture content)? Because that's the case for limestone powder obtained by chemical precipitation such as regeneration of caustic solution. 24.23.196.85 (talk) 02:12, 7 February 2013 (UTC)

Why do tortoises live so long?

Why do (some) tortoises live so long relative to other species, with some of them living 150 years or more? Thank you. Futurist110 (talk) 07:31, 2 February 2013 (UTC)

Well, part of it seems to be a slow basal metabolic rate. All things being equal, the slower the metabolic rate, the longer it takes for some types of damage, like oxidation damage to DNA, to accumulate to fatal levels. See free-radical theory of aging. StuRat (talk) 08:04, 2 February 2013 (UTC)

Other factors scientists are researching include DNA Damage Response and Repair Mechanisms.   ~Eric F 74.60.29.141 (talk) 08:10, 2 February 2013 (UTC)

I am tempted to make the wild speculation here that as random deleterious mutations accumulate over pre-reproductive lifespan, just so many mutations must be "excreted" from the genome via natural selection, or else the species would be overwhelmed and lost. It would seem to follow that a species must have either a good DNA repair, a short lifespan, or vigorous selection in order to survive... but this does not mean that the DNA damage would necessarily have to kill the individual, though it could, of course. Wnt (talk) 19:06, 2 February 2013 (UTC)

Because they are stupid and eat grass. μηδείς (talk) 21:45, 2 February 2013 (UTC)

Looking at it the other way, evolution wouldn't give any advantage to turtles who didn't live a long time, in that it takes a long time to harden the shell; any turtle whose natural life span was like a year after their shell had hardened would be at a disadvantage of having gone to so much effort for so little benefit. So the only turtles you'd see after their evolutionary niche had stabilized would be ones who live a very long time. Gzuckier (talk) 23:15, 2 February 2013 (UTC)

That's spurious reasoning; you could make the same argument that all animals should be long-lived. Also, why do you think it takes a long time to harden their shell? Even little turtles have nice hard shells; it hardly takes decades to form. If you don't know anything regarding a question, it would be best not to pretend that you do. There's good (sourced) stuff up above. Matt Deres (talk) 01:42, 3 February 2013 (UTC)

The spurious reasoning would be that they have better DNA repair; you could make the same argument that all animals should be long-lived by evolving the same mechanism. Your extension to other animals would seem to be reasoning from the axiom that turtles don't take longer than a normal reptilian lifetime to form shells, based on observations of little turtles; little turtles don't live that long, you'll note. Whereas, regarding somewhat larger desert tortoises, "Their shells become essentially incompressible (within 2% of complete shell inflexibility under a moderate force of 11.2 gm/mm²) by the age of about 11 years and a size of about 110 mm MCL." [2] (emphasis mine). Prior to my previous answer I had, of course, investigated all the Wikipedia articles on turtles, tortoise, turtle shells, plastrons, carpaces, etc., as well as all that google would deliver in order to bolster my memory of the slow ossification of turtle shells, and found only this source; at the time I didn't feel it directly relevant enough to cite, but I didn't expect the Spanish Inquisition. Gzuckier (talk) 02:48, 3 February 2013 (UTC)

Now if only parrots slowly grew a protective shell....Gzuckier (talk) 07:17, 3 February 2013 (UTC)

Invention v/s Discovery

Invention An invention is a unique or novel device, method, composition or process. It may be an improvement upon a machine or product, or a new process for creating an object or a result. An invention that achieves a completely unique function or result may be a radical breakthrough. Such works are novel and not obvious to others skilled in the same field.

Discovery Discovery is the act of detecting something new, or something "old" that had been unknown. With reference to science and academic disciplines, discovery is the observation of new phenomena, new actions, or new events and providing new reasoning to explain the knowledge gathered through such observations with previously acquired knowledge from abstract thought and everyday experiences. Visual discoveries are often called sightings.

Now question is , We all know that automobile Inventor Ferdinand Verbiest,If a new BMV car come in market then what it called Invention or Discovery. — Preceding unsigned comment added by Sanilblaze (talk • contribs) 09:01, 2 February 2013 (UTC)

It would definitely be called an invention. Maybe if there's some new physical principle involved it could be a called a discovery. but just a car is definitely an invention. 178.48.114.143 (talk) 09:34, 2 February 2013 (UTC)

[edit conflict]

Neither, it would be a replica or an adaptation of his innovation. Note however, the steam "car" designed by Verbiest in 1672 was a toy for Kangxi Emperor of China, and would not scale-up to an operational "auto-mobile" as we know it. It is debatable that Verbiest "invented the automobile".

• Verbiest did not think, either, that he had invented the automobile. In all humility he thought of his machine as "a method of movement" for which "other diverting applications are easily contemplated."

—Witek, jointly publ. by Institut Monumenta Serica, Sankt Augustin ... Ed. by John W. (1994). Ferdinand Verbiest : (1623 - 1688) Jesuit missionary, scientist, engineer and diplomat. Nettetal: Steyler Verl. p. 268. ISBN 3805003285.{{cite book}}: CS1 maint: multiple names: authors list (link)

~E:74.60.29.141 (talk) 10:00, 2 February 2013 (UTC)

Perhaps there is a Platonic realm of new car designs just waiting to be discovered. Gandalf61 (talk) 10:04, 2 February 2013 (UTC)

Perhaps the fact that we can compare the old car to the new car and show it is improved itself implies there is the objecive image of an ideal car somewhere - acceleration tends to infinite, fuel used tends to 0, etc ---- _nonsense ferret 14:20, 2 February 2013 (UTC)

Intuitively, it seems like it should be obvious that DNA sequences and Penrose tilings are discovered, rather than invented, no matter what the patent or copyright offices may say about the matter. The radio spectrum is something to be discovered, even if the particular arrangement of readily available parts in a specific radio is an invention. And the idea of having, say, a "steam powered car" or "gas powered car" or "nuclear powered car" should be something discovered, or simply an obvious combination of words, rather than an invention, though actually making it is an invention. So I would think that the essence of invention is taking specific fallible, real-world components with real world limitations and variances and tolerances and coming up with a way to do something with them, whereas the essence of discovery is to understand some universal standard from the Platonic realm or from the common legacy of the human race (genes, types of minerals, etc.). A person from an alien race on an alien planet should discover the same things we do, but invent different things. The Platonic ideal of a car should be determinable by doing archaeology on planets of many different stars to find common features. But this is all, alas, a question (or hypothesis) rather than an answer; I'm not even sure how to find reliable sources for any of this. (I should note that there's some tension expressed in the "or" above - I cannot exclude discovery of a specific legacy item though, unless we want to say that Columbus invented America. But there's a difference between discovery of America, which aliens could only make by travelling here, human genes that they can only discover with a sample, etc. and discovering fire or powered flight, which they could do at home) Wnt (talk) 18:45, 2 February 2013 (UTC)

SHD distribution on optical high speed networks

hw SHD distribution on optical high speed networks takes? — Preceding unsigned comment added by 223.228.36.112 (talk) 10:18, 2 February 2013 (UTC)

This question cannot be answered as it does not make sense. Presumably SDH is Synchnonous Digital Hierachy, but what is hw? Takes what? Your IP address gelocates to Bengalore India. You need to take care to write sensible and complete English if you want a useful answer. Keit 124.182.26.251 (talk) 15:06, 2 February 2013 (UTC)

I presume hw is how. I don't think takes is really the best word for what the OP is saying, probably instead something like 'works' or 'is used' or 'is done. Nil Einne (talk) 19:40, 2 February 2013 (UTC)

Or write the question in your native language, and we will translate for you. StuRat (talk) 16:13, 2 February 2013 (UTC)

Thanks

Thanks to all those who answered my January 28 question "Why don't the the sunrise and sunset times go the other way at the solstice?" [3] which has now disappeared into the archives. The answers were very informative. Richerman (talk) 12:57, 2 February 2013 (UTC)

You're welcome. StuRat (talk) 16:14, 2 February 2013 (UTC)

Historical election to fellow of RAeS

I am helping a new editor research the biography of Roy Chaplin. Is the process for the election to a fellow of the Royal Aeronautical Society (RAeS) in 1939 documented anywhere? I suspect that one of Chaplin's papers, presented to the RAeS in 1939, was used as part of such an election process. Are fellowship elections to Royal Society's gazetted?

I see a recently example where it was noted in Aviation Week & Space Technology - but that only started in 1947 so not much help sorry. ---- _nonsense ferret 14:24, 2 February 2013 (UTC)

I've also searched the Gazette for you, but the only reference I can find to his name is the OBE. I did find a couple of other newspaper references so I've added those to the article in userspace, hope that helps a little bit ---- _nonsense ferret 14:58, 2 February 2013 (UTC)

There is a reference to "1960 R.H. Chaplin (Fellow)" as a RAeS Silver Medallists [4] which at least seems to show he was already a fellow, not sure if that helps ---- _nonsense ferret 15:52, 2 February 2013 (UTC)

I drew a blank too in the gazette. I'm not even sure whether fellowship awardselections are gazetted. Your RAeS source does narrow down the time-frame of Chaplin's fellowship election to between 1939 and 1960 and additionally confirms his 1960 silver medal award, thank you. Thank you too for the additional further reading --Senra (talk) 16:13, 2 February 2013 (UTC)

Ground state and vacuum state

Are these synonyms? If not, what is the difference? The articles aren't clear on the point. FT2 ^{(Talk | email)} 18:32, 2 February 2013 (UTC)

No. The vacuum state is the ground state of a quantum field. Every quantum system has a ground state (its lowest-energy state), but only a field has a vacuum state. Looie496 (talk) 18:41, 2 February 2013 (UTC)

Concise, thank you! Can you elaborate a bit and (perhaps equally concisely) clarify the significance of the term "quantum system" (as opposed to quantum field/fields)? Thanks FT2 ^{(Talk | email)} 20:15, 2 February 2013 (UTC)

A quantum system is any system that obeys quantum behavior (Specifically, it obeys quantum commutation rules for the system coordinates and their canonical momenta). A quantum field is a quantum system with infinite (In fact uncountably infinite) degrees of freedom - that's what the word field mean. The simplest fields - scalar fields - have one degree of freedom for each point in spacetime. Note that spacetime has uncountably infinite points. That's in opposition to particle quantum systems (AKA first quantization) which have finite number of degrees of freedom - three space coordinates for each particle (Or countably infinite in case you have infinite particles). Dauto (talk) 01:26, 3 February 2013 (UTC)