Wikipedia:Reference desk/Archives/Science/2011 February 19

= February 19 =

Explosively formed penetrator efficiency
About how efficient would this be in terms of transferring chemical energy in the explosive to kinetic energy imparted to the penetrator? ScienceApe (talk) 03:18, 19 February 2011 (UTC)
 * The chemical energy is converted into 1) kinetic energy (ie. that due to the projectile's initial velocity after the explosion) and 2) the energy necessary to "re-shape" the material of which the projectile consists. How much energy is required for that second process can be complicated, and I haven't been able to find a very good generally-applicable answer for you, but see eg. Plasticity (physics).  You may also be interested in our Shaped charge article.  WikiDao    &#9775;  14:32, 19 February 2011 (UTC)

Relativity
Is it possible for a bubble of spacetime to exist within this universe under the following conditions:


 * There are two observers, observer A is located within this universe, B is located in the bubble.
 * A and B agrees on the temporal vector however, they do not agree on the dimension vectors - each observer claims that the other's space is inversed, left is right, up is down.

Plasmic Physics (talk) 04:12, 19 February 2011 (UTC)


 * Your question as it stands isn't well defined. People can "claim" whatever they want; you need to specify some kind of physical reversal effect that everyone agrees took place. For example, is there a spacetime manifold in which you can leave on a voyage and come back mirror-reflected (compared to someone who stayed home)? The answer to that is yes, since space could be shaped like the 3D analogue of a Klein bottle. But this is not really a relativistic question. General relativity doesn't say anything about what spacetime shapes are allowed. The Standard Model of particle physics is not mirror-symmetric, which suggests that such spacetimes aren't possible. -- BenRG (talk) 04:59, 19 February 2011 (UTC)

I'm not attempting to discuss the topology of the universe, only of a completely enclosed domain within the universe. The surface of the bubble is such that both observers may freely transit the bubble. There is no way for either observer to determine their absolute dimentional directionality, as there is no absolute reference frame. All they can say, is that the opposite observer's dimensionality is reversed. Plasmic Physics (talk) 05:29, 19 February 2011 (UTC)
 * (EC) It's not clear what you mean by "a bubble of spacetime ... within this universe". Our universe by definition is a single connected spacetime manifold; see Universe.  If there was a bubble of spacetime that's different from our normal universe, it would be a different, disconnected universe.  The laws of physics in our universe have CPT symmetry.  Parity alone is not conserved, as weak interactions violate parity, so a left vs. right transformation alone, or an up vs. down transformation alone, makes a difference as to our laws of physics.  Ideas have been floated that perhaps there exist other universes that have different laws of physics, or at least have different values for physical constants, but such ideas are of course highly speculative, and are probably unfalsifiable.  Red Act (talk) 05:34, 19 February 2011 (UTC)


 * I still don't think the question makes sense. In a lot of relativity textbooks there are poor imitations of Einstein's thought experiments with wording like "observer A claims [something], while observer B claims [something different]". The physical content of these examples is no different from "observer A claims that she is larger than observer B, while observer B claims that it is he who is larger than observer A." The description of the relative sizes of objects in these people's visual fields is correct, but the use of the word "claims" is inappropriate, since it suggests that these observers reject the reality of the other's perceptions and are unable to understand the difference between the perception and the objective world. There are people like that in real life, admittedly, but I think the people in thought experiments should be competent scientists. If you're using the word "claims" in that way, then what you're really asking is whether it's possible for two people to each see the other as mirror-imaged or as upside-down. The answer is yes, since you can just place a mirror or lens at an appropriate spot between them. I know this isn't a very satisfying answer, but it may be the only correct answer. -- BenRG (talk) 06:47, 19 February 2011 (UTC)

That is exactly what I'm asking, but I'm asking whether it is at all possible without the use of a lense or mirror like object, a situation where the observation of parity reversal is independent of the relative location of either observer within their dommain with respect to the bubble's surface. The effect is only observed for lenses within a limited range for a lense or mirror. Plasmic Physics (talk) 08:16, 19 February 2011 (UTC)
 * Oh, I get it. I'm sorry about the confusion. As a question in flat-space optics I think the answer is provably no, but I'm not sure. As a question in general relativity I'm not sure it makes sense, because whatever gravitational effects apply to light crossing the surface will also apply to matter crossing it. Maybe you could get around that with some crazy spacetime where lightlike geodesics get flipped around and timelike geodesics don't, but it seems dubious. -- BenRG (talk) 09:43, 19 February 2011 (UTC)
 * Maybe if the bubble was a spherical "trench" in spacetime (circular trench in 2D spacetime)? It could quite easily refract the rays of light.

So, the solution is purely an optical manipulation. A circular trench wouldn't cause these effects, the light would be refracted around the bubble turning it invisible, rather like a metamaterial. Plasmic Physics (talk) 14:04, 19 February 2011 (UTC)
 * You could twist spacetime, like it gets twisted around a spinning black hole, but you'd need a lot of twist. Manish Earth Talk •  Stalk 16:10, 19 February 2011 (UTC)

It's not clear what the exact condition you're looking for. If you place two persons in Quito and Singapore, they will disagree about the up/down and east/west directions, but still agree about north and south. If you have two observers disagreeing about the signs of all three spatial dimensions, their disagreement will have to be purely conventional in the sense that you cannot turn one's experience continuously into the other's without passing through a degenerate state. (The transformation from one's coordinates to the other's will initially have negative determinant, and the determinant cannot pass through 0 while still denoting something physically meaningful). –Henning Makholm (talk) 17:56, 19 February 2011 (UTC)


 * And that discontinuity seems exactly what is implied by "bubble". I'm picturing, in this discontinuous case, a domain wall separating two independently-crystallized bubble-universes (a consequence of, say, a chaotic inflation scenario), though I could also see it as a kind of wormhole effect where the twist happens when you tunnel from one end of the universe to another. I'm reminded of the story in Sphereland (a sequel to the classic Flatland) where these flat dog-shapes were usually born right-chiral ( /\--/\o ) but there exist rare left-chiral dogs ( 0/\--/\ which can be rotated in Flatland to \/--\/o, distinct from above). The three-dimensional visitor proves the existence of his dimension by rotating all of this young girl's right-handed dogs into left-handed dogs, much to her delight. If a wormhole tunneled through hyperspace to open in space on another end, perhaps you can go through and end up inside-out directionally (and physiologically)? Time would still run forward in this case. SamuelRiv (talk) 22:20, 19 February 2011 (UTC)


 * On further thought, I'll retract my claim about continuous transformations. To the extent that general relativity allows wormhole solutions, it most will certainly also allow globally non-orientable solutions where passing through the wormhole causes you to appear in the original universe with the opposite chirality. Whether such a wormhole can ever form from an orientable initial state is a different question (but perhaps not much harder than making wormholes in the first place, which is an iffy proposition at best), and particle physics (not the best friend of GR) would probably imply that the wormhole also exchanged matter with antimatter.
 * However, this does not sound very much like a "bubble" to me, so I'm still at a loss regarding what the OP actually meant here. If there is an actual boundary (at least a coordinate singularity if the metric becomes degenerate) between the inside and outside of the bubble, it is not clear how one would even compare the chirality inside and outside. –Henning Makholm (talk) 23:04, 19 February 2011 (UTC)

By "bubble", I meant a domain with a width, height, and depth, with an actual boundry defined by the enclosing surface. Plasmic Physics (talk) 00:46, 20 February 2011 (UTC)
 * But which physical significance does that boundary have? I see now that you say that your two disagreeing observers can cross the boundary freely. But still they disagree? What does their disagreement have to do with the bubble, then? And how is it different (observationally or conceptually) from simply saying that they disagree about what the words "left" and "right" mean? –Henning Makholm (talk) 01:41, 20 February 2011 (UTC)
 * For a wormhole to do such a chirality flip, it'd have to have a singularity in its throat. Basically, it should be shaped like a twisted bowtie. I don't know if that's possible...
 * No, you just take an ordinary orientable wormhole, cut through the throat, and glue the pieces together with one side mirrored, like a Klein bottle with an extra dimension. If the wormhole is sufficiently symmetric, the result will still satisfy the curvature equations at the gluing surface. (The point of using a wormhole is that I think this trick requires a spacetime that isn't simply connected). –Henning Makholm (talk) 16:38, 20 February 2011 (UTC)

They only disagree when they are on opposing sides of the boundry. I'm not sure what you mean by the difference. Plasmic Physics (talk) 07:14, 20 February 2011 (UTC)
 * If they are not in the same place, then how do they compare their orientations? –Henning Makholm (talk) 16:34, 20 February 2011 (UTC)

As long as they face each other they will always have a clear line of sight. Plasmic Physics (talk) 22:50, 20 February 2011 (UTC)


 * Henning, doesn't the existence of a wormhole in the first place imply space is not simply connected? SamuelRiv (talk) 18:38, 21 February 2011 (UTC)

Carbon black
wtf is carbon black — Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 05:15, 19 February 2011


 * Carbon black: "Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil....used as a pigment and reinforcement in rubber and plastic products" HiLo48 (talk) 05:25, 19 February 2011 (UTC)


 * The original ("informal") format of this question was restored, see the discussion and the relevant edit diff. Nimur (talk) 19:00, 19 February 2011 (UTC)


 * I don't understand the question. Please explain for our audience what "wtf" stands for. ←Baseball Bugs What's up, Doc? carrots→ 07:18, 20 February 2011 (UTC)
 * How could you tell it was a question? HiLo48 (talk) 07:25, 20 February 2011 (UTC)
 * You're right, it could also be a statement of fact. Thanks for leaving the non-native-English speaker baffled by insisting on the original wording. ←Baseball Bugs What's up, Doc? carrots→ 07:27, 20 February 2011 (UTC)
 * WTF, first definition. Nanonic (talk) 07:28, 20 February 2011 (UTC)
 * So, what has sexual intercourse got to do with carbon black? ←Baseball Bugs What's up, Doc? carrots→ 07:33, 20 February 2011 (UTC)
 * Probably a lot if we're talking about reinforcement of rubber and plastic products. Nanonic (talk) 07:35, 20 February 2011 (UTC)
 * The original "wtf" was the kind of wording a child would use. Other editors are constantly yelping about how this page is intended to help not just the OP, but anyone else who might come along. Changing "wtf" to "what" was directed to that avowed purpose. Insisting on keeping it as "wtf" was not. ←Baseball Bugs What's up, Doc? carrots→ 07:44, 20 February 2011 (UTC)

height (and body size, really) variance in animals besides humans -- or the lack thereof?
The article human height places responsibility for the great variability in height across Homo sapiens largely in the hands of health and genetics. Now, I am a birdwatcher, and it occurred to me the other day that I could not recall ever seeing a crow or pigeon that was a head above his peers. Observing the Eurasian Tree Sparrow, of which we have many in China, one can note slight variations in body weight (particularly towards the end of winter) but again - no feathered Yao Ming or I suppose Deng Xiaoping stands out among the crowd. Are humans unusual among animals with respect to their readily observable variance in body length? I am excluding, of course, those species which never cease to grow - we must confine ourselves to those that reach a defined adult form and cease growing. The Masked Booby (talk) 09:33, 19 February 2011 (UTC)


 * I thought in many mammals where size advantage in competition for a mate knocked up against genetic disadvantages of being too big there was reasonable variability. Certainly there seems to be size difference between adult male deer, and between adult hares and adult rabbits. Presumably the rest of the animal kingdom too but I can only speak for the ones I see often. --BozMo talk 10:06, 19 February 2011 (UTC)


 * Consider the domestic dog, which ranges in size from the chihuahua to the Alaskan Malamute or Irish Wolfhound. This variance is the product of years of selective breeding. This, I think, is the key to your question: among domestic breeds, there is a great variation in size, but their wild equivalents are all pretty much the same. --TammyMoet (talk) 10:12, 19 February 2011 (UTC)
 * Comparing dog breeds is going to be misleading as the dogs were essentially genetically engineered (the old fashioned way) to show the characteristics of the various breeds. Googlemeister (talk) 19:34, 22 February 2011 (UTC)
 * One major difference is that humans are "generalists", while most species are "specialists". That is, most species occupy a specific niche and location, and are customized for those only.  Humans, on the other hand, occupy many locations and niches, and so were customized differently for each.  I suspect that if you find a single species which is as widely spread as humans, then it will also have as wide a variety in physical attributes by population.  However, humans have been moving around, out of our natural environments, for centuries now, so you will now find people with attributes designed for the poles living near the equator and vice-versa.   StuRat (talk) 21:14, 20 February 2011 (UTC)

Dog mortality and longevity
Looking at the links above relating to the longevity of various dog breeds, I was surprised that they may on average only live 6-7 years and then die of cancer. 1) Why do dogs get cancer so early compared with humans? 2) Which dog breeds live longest, and least? 3) Is there any rule which predicts dog longevity from the breed size, etc? Thanks 92.15.16.146 (talk) 13:09, 19 February 2011 (UTC)
 * WP:OR generality here but small dogs often live longer than large dogs. Oh, and if you want a source with some data, here ya go.  Dismas |(talk) 15:03, 19 February 2011 (UTC)
 * This is an area where numbers are varying rapidly due to social changes, and not evenly. People in advanced western nations these days seek more veterinary help for their pets than they would have 50 years ago. This makes a big difference. Some more very personal OR: breeds like Beagles, which are prone to escaping and demonstrating little road sense, are being penned and restrained more successfully these days, meaning that they are are overcoming their genetic predisposition to being run over. So that breed is experiencing a bigger improvement in longevity than some others. HiLo48 (talk) 15:21, 19 February 2011 (UTC)
 * OR here, but mongrels seem to live much longer and healthier lives than highly bred animals. DuncanHill (talk) 20:14, 19 February 2011 (UTC)
 * There are definitely certain breeds of dogs that are known to have lots of problems that can be mitigated by crossing breads (i.e. making Mutts). Cocker Spaniels often get Hip dysplasia, for example.  See Purebred_(dog).  The American Kennel Club has gotten a bit of flak about this, in that they don't permit member clubs to maintain health standards in addition to the appearance standards imposed by the AKC. Buddy431 (talk) 23:14, 19 February 2011 (UTC)

Milk of Magnesia/Mike and Ikes
I recently discovered (about 5 minutes ago) that the candy Mike and Ikes contain magnesium hydroxide in trace quantities. Isn't that the main component of milk of magnesia, an antacid/laxative? Why is it there? Finalius ( Say what? ) 13:33, 19 February 2011 (UTC)


 * I would imagine that the concentration in the candy will be very low. Magnesium hydroxide can fill a number of roles in foods and supplements, including "Drying Agent, pH Buffer, Antacid, Color Retention Agent".  I suspect that its purpose here is to act as a drying agent, to keep the individual candies from getting tacky and sticking together. TenOfAllTrades(talk) 15:05, 19 February 2011 (UTC)
 * (ec)According to WHO/FAO, it's an additive used as an "Acidity regulator [and] Colour retention agent". As with many, many chemicals, a megadose can have very different effects than a small amount mixed with some other material. Also, we don't know (and I bet Just Born won't tell us) exactly how it's used...in combination with other ingredients, it could react to form different chemicals with different properties rather than just being diluted to low levels. DMacks (talk) 15:09, 19 February 2011 (UTC)

Why is the sun not purple or why is hydrogen plasma not yellow?
According to the article, hydrogen, the plasma state is purple, but the sun is yellowish, but it's made primarily out of hydrogen plasma. I know that black body radiation means that it should glow yellow according to that temperature, but then shouldn't hydrogen plasma glow yellowish too then if it's the same temperature? ScienceApe (talk) 16:28, 19 February 2011 (UTC)


 * What makes you think the purple discharge shown in the hydrogen article is at the same temperature as the Sun('s photosphere)? –Henning Makholm (talk) 18:00, 19 February 2011 (UTC)


 * The image of "purple" hydrogen is dominated by spectral emissions, not thermal radiation. Hydrogen plasma can be purple because one of the characteristic Hydrogen electron transitions (specifically, the 6→2 transition is purplish.  In this particular lab-setup, that energy level has been stimulated.
 * The sun's spectrum is dominated by thermal blackbody radiation - that is, it is not spectral emission lines. Our sunlight article has a whole section on solar spectrum composition explaining the details.  There are a few "peaks" and "notches" superimposed on top of the ideal black-body curve, due to photochemical absorption (i.e. spectral absorption) and atomic emission spectra inside the sun.  The spectrum received at Earth's surface is further "notched" by spectral absorption of chemicals in the Earth's atmosphere (in the visible spectrum, most absorption lines are caused by water, CO2, and a few ions).  Nimur (talk) 19:10, 19 February 2011 (UTC)


 * Well I assumed that plasma is still pretty hot. I know you can get cold plasmas but I just assumed that plasma was hot. I dono, maybe it's not hot. Could a black dwarf look purple in that case? ScienceApe (talk) 19:32, 19 February 2011 (UTC)


 * It's a question of optical depth; while the plasma emits more at the spectral lines of hydrogen, it also absorbs more in these parts of the spectrum. You can imagine a piece of plasma absorbing the incoming light at the spectral lines strongly, but absorbing far less (in relative terms) of the light between the spectral lines. This piece of plasma will then emit strongly at the spectral lines and weakly between the spectral lines. The resulting light will have a lower ratio of light intensity at the spectral lines and between the spectral lines than the incoming light. In other words, you see deeper into the Sun at frequencies which are not at the spectral lines of hydrogen, and if you would put many such purple laboratory plasma vessels behind each other, they probably wouldn't look purple anymore. Icek (talk) 20:34, 19 February 2011 (UTC)


 * You do get purple light from optically thin HII regions in the interstellar medium. The purple line is actually the red Hα line (6565 Angstrom), that is the 3-2 transition (6-2 is Hδ which is weaker and lies at the blue/violet end of the visible spectral range). These lines arise when an electron and a proton in an ionised hydrogen gas recombine to form a hydrogen atom; the electron cascades down to the ground level (n=1) and in the course of that cascade, many electrons go through n=3 and n=2, making Hα one of the strongest emission lines. In an optically thin gas, the photons emitted that way escape immediately. In an optically thick gas, they are reabsorbed very quickly. In the sun, the radiation originates deep in the core of the sun, and while diffusing outwards is scattered, absorbed and reemitted many many times, leading to thermalisation of the radiation and thus a black-body spectrum. This spectrum is modified by the outermost layer of the sun, just when the radiation leaves the sun. This modification takes the form of absorption lines, not emission lines. --Wrongfilter (talk) 20:46, 19 February 2011 (UTC)
 * I'm confused. How can it be possible that "purple line is actually the red Hα line"?  This seems to be a non-sequitur or a typo... do you mean to say "the strongest line" is the red Hα line?  Hα may be stronger, but is always red; Hδ may be weaker, but is always purple; their relative intensities depend on the plasma properties.   Nimur (talk) 22:27, 19 February 2011 (UTC)
 * I should have said "the purple colour is due to...". Purple is a mixed colour and not a good designation for a single line. In astrophysics, I am not aware of any plasma where Hδ (which I would describe as violet) would be stronger than Hα; in those spectra that I am familiar with, it is much weaker. --Wrongfilter (talk) 23:08, 19 February 2011 (UTC)
 * My description might have been misleading; the reason for the lines being absorption is that the outermost layers are the coolest layers, therefore in these layers it will more often happen that an atom absorbs radiation than that it emits radiation. That's of course not the case with many many laboratory plasma vessels; the lines would vanish alltogether if there is a sufficient number of them. Icek (talk) 21:00, 19 February 2011 (UTC)


 * Note that file:Hydrogenglow.jpg shows a glow discharge in a cold plasma. The purple light is only there because the plasma is being pumped to a higher ionization than it would have at equilibrium for its temperature. (I think the spiral thread around the tube carries RF current to provide the excitation energy). The Solar photosphere is much hotter and in rough equilibrium between ions and neutral atoms, so it doesn't show strong emission lines, compared to its blackbody spectrum. –Henning Makholm (talk) 01:34, 20 February 2011 (UTC)

Common hazel (Corylus avellana)
Can the climate in the midwestern US support common hazel (Corylus avellana)? --75.15.161.185 (talk) 19:56, 19 February 2011 (UTC)
 * Given its range in Asia, the midwestern climate certainly can. However, our article on Corylus americana gives an indication that Corylus avellana is vulnerable to a type of fungus that is found in North America. Looie496 (talk) 23:50, 19 February 2011 (UTC)

comments on this experimental design to test homeopathy?
I'd like to test the basic premise of homepathy. I was thinking of doing it like this.

Get thirty small plants, put them on a very large table, also six large, empty squirt bottles, and thirty small and thirty larger envelopes. Create thirty cards, ten with "A" on them, ten with "B" on them, and ten with "C" on them. Shuffle ten of the cards face down. Without looking at what is written on it, put each one in a small envelope, sealing it. Then shuffle all the small envelopes again thoroughly. Put each one in a big envelope, sealing that one as well. Shuffle the big envelopes thoroughly, and put one in front of each plant, without opening any of them.

Next set aside three of the six squirt bottles. These are supposed to be the pristine bottles, don't touch them again. However, do one thing: repeat the above procedure with three more cards, one labelled "A", one labelled "B", and one labelled "C". Shuffle them face-down, put one in each of three small envelopes and seal them, shuffle them again, and put one in each large envelope, shuffle them again, and tape one envelope onto each pristine bottle.

The remaining three bottles, handle like this. In one, put Nutri-Grow plant supplement. The second, fill with tap-water. In the third, put Nutri-Grow supplement, then dilute it with water. Mix well, and discard most of it. Dilute it with more water, and repeat, diluting, mixing well, and discarding. Per homepathy, the more you dilute in this way, the greater the homeopathic strength. Repeat the process until you have uber-strength.

Now there is just one step before you begin. You have to be blinded to which of earlier set-aside three bottles will contain which of your three concoctions.

So one last time, you create three cards, reading "1", "2", and "3", shuffle them face down, put one in each of three small envelopes and seal them, shuffle those face down, then put one in each of three large envelopes and seal them. Shuffle again, and put one in front of of each bottle you have handled. Finally, write the phrase "Label of what it is" on three large envelopes, and put them face-dwon and shuffle them. (So you only know that the large envelopes will say "label of what it is", but the handwriting can't give a clue). You write the actual name of the the concoction "nutrigro", "water", or "homepathy" respectively on a card. This time you don't shuffle them! Carefully keeping track of each one as you're doing it, you put the label of what it is on a card, you put the card in a small envelope and seal it, then you put the card in a large envelope that already reads "Label of what it is" and seal it, and you put it by that bottle.

So, this is what you have now. Next to each water bottle, you have two envelopes, one unmarked and one marked "Label of what it is".

The three pristine water bottles you haven't touched already have one envelope on them.

Now you leave the room and ask someone else to do one simple thing. Being careful to keep "label of what it is" with each used water bottle, they are to do the following. They open the unmarked envelope next to the used bottle, read a number "1", "2", or "3", and put the contents of the used water bottle into that pristine bottle (i.e. the first, the second, or the third pristine bottle). Then they tape "label of what it is" to that pristine water bottle. It's important that they do this one at a time and not mix up the "label of what it is".

Okay, now they leave, taking the used water bottles, the opened envelopes, and the cards 1, 2, 3. I only come back after they've left.

Now I'm properly blinded (and they also don't know which water bottle is A, B, or C). I have three squirt bottles, each with one unmarked and one marked envelope ("label of what it is") taped to them. On each one, I open the unmarked envelope, open the smaller envelope, take out the card, and tape it to the squirt-bottle. Now the squirt bottles are labelled "A", "B", and "C", and there is an unopened card on each one reading 'label of what it is'.

The next part is easy. I open the cards next to the thirty plants, so that they become labelled with "A", "B", and "C" randomly (not really in groups or anything). For a few weeks, I use the contents of the squirt bottle, A for the A's, B for the B's, and C for the C's, as a plant supplement. I can possibly tell which one is NutriGrow, because it's not just water, but I couldn't tell homeopathy from water, so I am absolutely unbiased and can't influence the results.

After a few weeks, I ask my friend to come measure the plants (I don't do it myself because I'll probably learn by then which one is NutriGrow). Now we have ten measurements for A, for B, and for C.

We do statistics. The prediction is that the data in one of them is clearly able to be differentiated from the data in the other two, since it involves real plant fertilizer. However, two of the three groups should be statistically indistinguishable.

The most amazing result would be if all three groups were clearly different with high statistical confidence. That would be pretty startling.

In any case, I would publish the results on the Internet. Then I would unblind, by reading "Label of what it is" on each of the bottles A, B, and C. There is one more room for shock here: maybe two of the groups were the same, but that's because homeopathy is JUST as effective as NutriGrow! So, if the group that got water supplement grow slower than NutriGrow, but the Homeopathy group grew just as fast as NutriGrow group, that would be pretty amazing. Also amazing is if Homeopathy group grew statistically better than water, but worse than NutriGrow. or, statistically better than nutrigrow, or statistically worse than water. all of these would be startling.

equally starting would be if water were more effecitve, statistically, than nutrigrow :) So, the experiment would also incidentally test that.  The 'null hypothesis', if I'm using that word right, is that one group will statistically grow more, and the other two - the water and homeopathy - will be indistinguishable.

What do you guys think? 109.128.192.218 (talk) 23:38, 19 February 2011 (UTC)


 * I've collapsed the description, which really doesn't belong here anyway. To answer the question, what I think is that this is an awful lot of trouble to go to to show that homeopathy does not work on plants. Looie496 (talk) 23:59, 19 February 2011 (UTC)


 * If I have a table of appropriate size, it will take half an hour to bring plants in and set them up, maybe another half hour to do the blinding, and then about two to three minutes a day for, say, 30 days, i.e. another hour and a half. The cost would be probably less than $100.  I think this is not too much work to have a scientific answer to whether homeopathy works.  Moreover, I expect a one in twenty chance of showing that homeopathy works at the 95% confidence level, in which case I could probably get $10,000 for the research from the "industry".  In other words, the expected value of the research of the search is 5% * 10k = $500 but the cost is only <$100.  So, it's not too much work at all, really... Of courwse, because of the prior probability (the fact that homeopathy can't possibly work) 95% confidence isn't nearly enough to establish anything, but I think that woon't stop homeopathic companies from paying 109.128.192.218 (talk) 00:30, 20 February 2011 (UTC)


 * You might want to read our Homeopathy article for further ideas about testing its efficacy, and what such testing is claimed to have demonstrated so far. The Effect in other biological systems section of that article says something about homeopathic effects on "grain" but I could not find any other mention of your interest in homeopathy as applied to plants.  I don't know much about it, but I had the impression it was mostly something believed to have effects on people.  Your experimental design for the plant thing sounds okay, though I agree with Looie that it seems like a lot to go through to test something that really isn't even being claimed all that much by homeopathists  afaik.  So: why not work on coming up with some similar experiment with people (or maybe even some suitable lab animals?) as test subjects...?  WikiDao    &#9775;  00:50, 20 February 2011 (UTC)
 * because if diluting shit until the water only has a memory of it makes the shit stronger, then it will work with nutrigrow. by taking the people out of the equation, if there IS an effect, my experiment would be super-famous forever.  It's not like I'm testing a different mechanism from people-homeopathy.  It's the same concept, minus placebo effect. 109.128.192.218 (talk) 01:56, 20 February 2011 (UTC)
 * So go for it. You'll want to get it published in a respected peer-reviewed scientific journal if you want to be super-famous forever taken seriously by anyone, though.  WikiDao    &#9775;  02:09, 20 February 2011 (UTC)


 * Though keep in mind that the ability of people to find ways to make vague theories fit any data is nearly unlimited. "Oh, we never said it would work with fertilizer, or on plants," goes the obvious response. "Of course you'd get that result. We'd have predicted that ourselves using our own models." --Mr.98 (talk) 03:26, 20 February 2011 (UTC)


 * What should be done to the plants was explained by Terry Pratchett and Neil Gaiman in their book Good Omens. 66.108.223.179 (talk) 01:27, 21 February 2011 (UTC)


 * If the "basic premise" of homeopathy is that like cures like, then you're not testing it because you're not attempting to cure the plants of anything. (That is, after all, what the word "homeopathy" actually means.) You are also not scientifically diluting the mixture. At least those making the diluted preparations for homeopathic use do it very, very precisely: I see no indication in your method that you will do that. Also, homeopathic prepations are not only diluted, but shaken (the term used is succussion). Homeopaths claim that it is this succussion that imprints the chemical on the memory of the water: again, you do not mention that. Once you have copied exactly the processes used by homeopathic chemists, then you can start your experiment. Oh and don't expect the scientific world to take you seriously if your results are anything but "homeopathy doesn't work". There are plenty of studies that show positive results for homeopathy, but scientists take great pleasure in picking them apart and saying "oh the sample size was too small" or "it didn't work because homeopathy can't work, must have been something else that worked, therefore the experiment was flawed". Besides, if you approach the experiment with the intention to disprove homeopathy, then you have destroyed the experiment. Your intent also skews the result. --TammyMoet (talk) 09:05, 20 February 2011 (UTC)


 * I think you missed that for each step in the dilution process you need a clean bottle. Have anyone claimed that highly diluted fertiliser would work? If not I do not think your test will show anything important. (Homoeopaths will claim it is a straw-man). I think it would be better to test a commercialy available homoeopathic product (and analyse it to see that it really was highly diluted). Gr8xoz (talk) 16:32, 20 February 2011 (UTC)


 * If that did work, I think that farmers would be more interested than homeopaths since you'd save them a shed load of $$$ on fertiliser every year. Nature already does that test though pretty much - rainwater is very dilute nitric acid and nitrous acid but plant evidently grow faster when they have fertiliser too. SmartSE (talk) 23:21, 20 February 2011 (UTC)


 * That is a good point, and thus it may have relevance to people in the agricultural sciences, even if only for them to set it in stone that "this is wrong, so don't even try it if you thought of trying it". So yes, why not try the experiment. But I'll second the requirement that you must use a fresh clean bottle each time, because both you and homeopathists don't want the medicine "contaminated" by an actual active ingredient. SamuelRiv (talk) 18:56, 21 February 2011 (UTC)