Wikipedia:Reference desk/Archives/Science/2011 March 30

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March 30

Spreading mineral matters on earth

The general oxidation of earth crust might be after the time once the earth surface was molten ,the outer crust material complex and the location of mines such as aluminum and Ferro and copper in Alp -Himalaya belt shows us that thoroughly it was our earth surface molten for about 800 million years , and when any asteroid with mineral matters hinted our earth it had to be molten and spread on earth surface.(A. mohammadzade ) --78.38.28.3 (talk) 05:15, 30 March 2011 (UTC)

Is there a question here ? StuRat (talk) 05:23, 30 March 2011 (UTC)

Also, let me suggest that you also post in your native language (and tell us what it is), as we might be able to translate it better than you. Your English is barely readable. For example, "Coeur" isn't an English word. It means heart in French, but that seems wrong in this context. Did you mean copper ? StuRat (talk) 05:26, 30 March 2011 (UTC)

I can't find a question, but the OP may find useful information on the cooling of the earth at History of the Earth and Hadean Eon. The asteroid impacts he is talking about occuring during Earth's molten phase happened during the Late Heavy Bombardment period. The ancient cores of continents, believed to date from the Hadean, are called Cratons. The location of ore deposits and how they formed are complex geochemical processes known as Ore genesis. All of the links I provided here should answer any questions the OP may have, given the various statements he made. --Jayron32 05:29, 30 March 2011 (UTC)

the continues spreading shows the question about the subject late heavy bombardment say me about this ,and first earth creation .--78.38.28.3 (talk) 05:36, 30 March 2011 (UTC)a. mohammadzade THANK YOU

Please post your question in your own language as your English, which I suspect is a machine translation, is unintelligible. Roger (talk) 13:19, 30 March 2011 (UTC)

His IP suggests he is from Iran. At any rate my guess is that he wants to know is if meteorite strikes have any relation to current composition of Earth's crust (i.e. have they changed location of minerals and metals in it) ~~Xil (talk) 15:37, 30 March 2011 (UTC)

If so, he might be interested in our article on the Sudbury Basin. Matt Deres (talk) 18:35, 30 March 2011 (UTC)

How do you ask him to post in Farsi, in Farsi? 92.15.1.33 (talk) 16:17, 30 March 2011 (UTC)

I will post a request for assistance at the Language RefDesk. Roger (talk) 16:32, 30 March 2011 (UTC)

با در نظر گرفتن جایگری معادن در رگه هایی که به صورت تقریبا پیوسته مابین قاره ها امتداد یافته اند برای مثال معادن آهن و الومینیوم و مس به صورت تقریبا خطی بر روی کره زمین گسترده شده اند دو نتیجه می توانیم بگیریم .یک اینکه این معادن اقفاقی در یک خط قرار گرفته اند ودوم اینکه زمین در هنگام اختلاط هریک از این معادن با خاکش به صورت مذاب بوده است و هر سنگ اسمانی حاوی این عناصر را ذوب و در یک امتداد مثلا طولی یا عرضی کشیده است و با انشقاق قاره هابه شکل کنونی در امده است . اگر در یک دوره سطح زمین به صورت گسترده مورد بمباران شهاب سنگ ها قرار گرفته و هریک دارای عناصر معدنی بوده با فرض جامد بودن جبه زمین در زمان یاد شده به این نتیجه می رسیم که معادن نباید این گستردگی خطی را داشته باشند این تناقض را چگونه حل می کنید ؟

—Preceding unsigned comment added by 78.38.28.3 (talk) 03:39, 31 March 2011 (UTC)

Here's its translation: knowing that mines are located almost continuously along veins across continents, e.g. iron, aluminium, or copper mines are located almost linearly on the surface of the Earth, we can get two results. First, mines were accidentally located in a line; and second, when earth was mixing with these minerals, it was in a molten state, and it melted every meteorite containing these ingredients and pulled them in a latitudinal or longitudinal line, and present forms appeared when continents took shape by splitting. But if Earth was solid when those meteorites fell, this linearity of mines could not be formed. How do you explain this contradiction? (I myself don't see any contradiction here though! I don't understand him clearly --Omidinist (talk) 05:48, 31 March 2011 (UTC))

Most minerals are found in veins, which are roughly tabular in shape, and therefore appear linear where they intersect the surface. They are mostly located along fault of fracture surfaces, that are generally of one or two distinct orientations in an area, relating to the stress field at the time of formation. Stress fields are often fairly constant in orientation over large areas, meaning that the faults/fracture and their associated veins are sub-parallel. If the stress-state changes, further mineralisation will occur along different lines, an example is the so-called 'cross-courses' in SW England associated with the cornubian batholith granitic intrusion, which run mainly north-south, cutting the earlier west-east main course veins. Mikenorton (talk) 07:37, 31 March 2011 (UTC)

If you are interested in reading about metal deposits that are forming right now and being mined have a look for the one on Lihir Island, "Ladolam", in Papua New Guinea. Sean.hoyland - talk 08:55, 31 March 2011 (UTC)

برای مثال به معادن مس و خاکهای حاوی مس دقت کنید که می توانیم آنها را به صورت رگه باریک از شمال غرب ایران تا جنوب شرق از منطقه سونگون آذربایجان تا سرچشمه کرمان مشاهده کنیم یا معادن آهن از زنگولداک ترکیه تا چغارت ایران در یک باریکه خطی قرار گرفته اند —Preceding unsigned comment added by 78.38.28.3 (talk) 09:26, 31 March 2011 (UTC)

OK 78, if google translate hasn't completely misled me, you are talking specifically about the porphyry copper deposits within the Urumieh-Dokhtar magmatic belt, formed as part of the Kerman arc during the collision between the Arabian Plate and Eurasian Plate. This is linear because it marks the location of a past subduction zone along that convergent boundary. Mikenorton (talk) 09:41, 31 March 2011 (UTC)

Most mineral deposits are formed through hydrological deposition interacting with soil strata. 99.2.149.161 (talk) 04:17, 1 April 2011 (UTC)

Milligram scale

We cannot offer you instructions on compounding pharmaceutical products. Please speak with your doctor or pharmacist if you would like to be able to safely adjust the dosages of your medication. TenOfAllTrades(talk) 22:44, 30 March 2011 (UTC)
The following discussion has been closed. Please do not modify it.
This question is a bit unorthodox, I realize, but: where can I get a scale that will accurately measure within 1mg? I am willing to pay no more than $100, $150 if I get really desperate. I looked on Amazon and found a lot of cheap ones that aren't precise at the 1mg level, which is unacceptable for me. And I see some more expensive ones but they don't have enough reviews for me to tell how well they'll work. I am willing to buy online, although buying locally would be even more ideal. Magog the Ogre (talk) 16:59, 30 March 2011 (UTC) What do you need the top end of the scale to be? Googlemeister (talk) 18:19, 30 March 2011 (UTC) Ugh, it turns out I have misread! I need it to be accurate to .01 mg, which I know is ridiculously precise, and probably not something I could find easily on the market. But to answer your question: no more than a few milligrams. Magog the Ogre (talk) 18:32, 30 March 2011 (UTC) You need an analytical balance. You 'might' be able to get a secondhand one on Ebay. A basic balance is not really going to be good enough though so make sure it has the resolution you need. What are you trying to weigh? There might be an easier way to achieve the end result --Aspro (talk) 19:04, 30 March 2011 (UTC) Ouch. A balance with a 10 microgram resolution is going to be costly, whether new or used. In the price regime you're describing, you just can't get precision equipment unless a) it's in need of major repairs; or b) you're buying it from someone who doesn't have a clue what it's worth. Properly packing and shipping a microgram balance is probably going to eat a good chunk of your budget, on top of whatever you pay for the instrument. Scientific American did run a column describing how to construct your own balance with your desired precision. If you're good with your hands, you can do it with less than fifty dollars in parts: [1]. The addition of a microcontroller allows you to automate the readout and tare funcions, and still can ring in under $100: [2]. TenOfAllTrades(talk) 19:11, 30 March 2011 (UTC) Re: Aspro: I am trying to measure my prescribed medication which I am splitting (the minimum dosage is .25mg, and I am cutting it in fourths, leaving ~.06 mg/dose; if I am off by even about 25%, I suffer undesirable side effects until my next dosage; my body is amazingly sensitive to tiny changes in chemistry... I can get pretty buzzed off just one beer for example). You will note I am not asking for medical advice (I've already talked to my doctor); I am asking about a scale. Magog the Ogre (talk) 19:58, 30 March 2011 (UTC) The cheapest one I can find after a (brief) search is about $1000. I would suggest asking your doctor if he can provide your medication in something like a pill which can be easily cut into quarters by hand. Or perhaps ask your local college/university if they have some old scales they're about to throw out? 50.92.121.76 (talk) 20:15, 30 March 2011 (UTC) I hope you realise that a pill containing .25mg active ingredient actually weighs substantially more than that. The bulk of the tablet consists of sugar, chalk or another non-bioactive carrier. If it was pure active ingredient the tablet would be like a tiny speck of dust. If you are unable to divide it accurately enough you could try disolving the tablet and then dividing the solution by volume - the more water you use the more precisely you can divide it: .25mg active ingredient disolved into 100cc of water would result in 2.5 microgrammes per cc. Syringes or pippetes that can accurately measure 0.1cc are widely available and dirt cheap. Roger (talk) 20:36, 30 March 2011 (UTC) Re: 50.*: a good idea; i have local contacts in a very large university chemistry department. Doesn't mean I'll get it though! Re: Dodger67: that is an extremely good idea which hadn't occurred to me. Unfortunately, according to the local Wikipedia article, "when crushed in water it will not fully dissolve." I may have to ask my chemist friend about the solubility though. Magog the Ogre (talk) 20:59, 30 March 2011 (UTC) Wow. As detailed as Erowid is about this stuff, they give neither the gross weight of the pill nor the composition of the oral solution form in which it is sold. Wnt (talk) 21:49, 30 March 2011 (UTC)

I can't be bothered with the elaborate brown rice recipes.

Is it still worthwhile to eat brown rice when I can't be bothered to cook it for a long time? 12.40.220.253 (talk) 17:21, 30 March 2011 (UTC)

It sounds like you are asking if it's OK to eat raw rice. Dauto (talk) 18:54, 30 March 2011 (UTC)

If you can be bothered to walk round the supermarket you can find it ready cooked – just needs two minutes in the microwave.--Aspro (talk) 18:55, 30 March 2011 (UTC)

Yes it is, the fibre is very good for you. The way I make rice is: add half a cup of rice and a full cup of boiling water to a saucepan. Bring back to the boil, then reduce the heat and simmer for 20-25 minutes (depends on the rice - could be 25mins for wholemeal, but down to only 15 for white or easy-cook rice - follow packet instructions). Check the saucepan from time to time to make sure it is not boiling dry. I use a timer to measure the time, as it is essential to remove the saucepan before it gets too dry and starts to burn. You can add chopped vegetables at the beginning, but this can introduce more moisture which may need draining off five minutes or so before the end. Best to be watching the saucepan for the last 5 minutes so that you can get the rice as dry as you wish, without burning. I prefer moist fairly soft rice. I use an open saucepan lid, so that all the interior is moist but which allows the steam to escape. I think you could alternately make rice with more boiling water and then drain and dry it after cooking. 92.15.1.33 (talk) 20:47, 30 March 2011 (UTC)

I was surprised when I had some Chinese and Malaysian borders at my place a couple of years ago, when they told me that NO ASIANS these days cook rice as described above. They ALL use rice cookers. And when I bought one, I could see why. They cost about nothing (say $20). you just put the rice in, cover it with water by a couple of fingers, put the glass top on, and turn it on. It will cook the rice perfectly, then switch off to "keep warm" mode. There is nothing to do at all, and the rice is ALWAYS perfect! I never use anything else now. No chance for burning or undercooking, and the cooker keeps the rice warm for hours. Try it. All the Asians use it, and they are the canniest buyers I know. Myles325a (talk) 00:12, 31 March 2011 (UTC)

But the rice in Asian cooking is usually sticky white rice. I think that some rice cookers won't work properly with other types of rice, so you should check that before buying. -- BenRG (talk) 04:27, 31 March 2011 (UTC)

And, the other part of the "is it worth it" calculation is based on how good it is for you. Take a look at the nutrition here: [3]. The good points are that lack of fat, saturated fat, cholesterol, sugar, and sodium (unless you need to add those things to make it palatable). It also has a moderate glycemic index (less than white rice). It's a mixed bag as far as vitamins and minerals, having lots of some (like manganese), and very little of others. On the bad side, it's also fairly high in calories (almost all of them from starch), low in protein (although it is almost complete in amino acids), and somewhat inflammatory. StuRat (talk) 04:25, 31 March 2011 (UTC)

You've forgotten the fibre, which most people do not get enough of. It is very much better than filling up on junk food such as "french fries" or pizza. 92.29.119.112 (talk) 10:43, 31 March 2011 (UTC)

I didn't list fiber since it had been previously mentioned. And french fries have a fair amount of fiber: [4]. They are unhealthy, but that's due to the salt and fat, not a lack of fiber. The same is true of pizza: [5]. StuRat (talk) 18:32, 1 April 2011 (UTC)

To cook brown rice in a rice cooker you just put in double the amount of water. It does take longer to cook, but it is almost no more work, so level of water=3xlevel of rice. Graeme Bartlett (talk) 21:43, 1 April 2011 (UTC)

Do you mean that the volume of water is double the volume of rice, or double the volume you normally use (whatever that is)? If you are putting in too much water, then you may be spending a lot of time merely evaporating the excess water for already cooked rice. Thanks 92.15.9.102 (talk) 09:45, 3 April 2011 (UTC)

Protein subunit names vs gene names?

Hi, I had a question about how it is that protein subunits get their names. I was under the impression that if an operon had the structure (for example, in the case of the perchlorate reductase enzyme) pcrABCD, the subunits would be alpha, beta, gamma, and delta (respectively). However, I just noticed that in the case of another enzyme, methane monooxygenase, the pmoCAB operon encodes gamma, beta, and alpha, respectively. So, how is it that biochemists name subunits? Is it not supposed to correlate with the genes (i.e., why is "A" not the alpha subunit?) Thanks for your help. Ccarlst (talk) 22:05, 30 March 2011 (UTC)

The subunits of the methane monooxygenase enzyme were discovered and characterized in the 1970s and 1980s (eg. [6], [7], [8], [9]). The biochemical data and protein sequence data were then used to map and clone the genes encoding the proteins in the late 1980s and early 1990s (eg. [10], [11], [12]). The original nomenclature of the protein components did not match up with the molecular biology, which has often been the case in the history of science, but in order to avoid confusion, we keep the standard biochemical nomenclature and accept a few inconvenient inconsistentcies such as the genes being arranged in a different order than their names would imply. --- Medical geneticist (talk) 13:02, 1 April 2011 (UTC)

So how it is that biochemists decide what is alpha, beta, etc? Also, what are the current standard names (and what is the correlation) between genes pmoCAB and alpha, beta, gamma subunits? Thanks for the help. Ccarlst (talk) 19:44, 1 April 2011 (UTC)

Acceleration and relativity

So using the Newtonian a = F/m it would seem an object could be accelerated to any speed. What is the relativistic equation that is asymptotic at the speed of light?   jorgenev (talk) 22:05, 30 March 2011

Four-force —Preceding unsigned comment added by 92.20.201.71 (talk) 22:51, 30 March 2011 (UTC)

(edit conflict):Our article Mass in special relativity explains that the apparent mass M at speed v is given by $M=m/{\sqrt {1-v^{2}/c^{2}}}$ (though this equation is not the best way to look at the situation). The acceleration is thus $a=F{\sqrt {1-v^{2}/c^{2}}}/m$ and gradually reduces towards zero as the speed approaches that of light. Dbfirs 23:00, 30 March 2011 (UTC)

That is totally wrong, and the article you linked to even includes a quote from einstein about the total vacancy of introducing the quantity $M={\frac {m}{\sqrt {1-v^{2}/c^{2}}}}$. Infact

${\mathbf {f} }={d \over dt}\left(\gamma m{\mathbf {u} }\right)=m\gamma \mathbf {a} +m\gamma ^{3}{\frac {\left(\mathbf {a} \cdot \mathbf {u} \right)}{c^{2}}}\mathbf {u}$ —Preceding unsigned comment added by 92.20.201.71 (talk) 00:31, 31 March 2011 (UTC)

I agree, that's why I said it's not the best way of looking at the situation. I thought that the OP was looking for a simplistic explanation (and first approximation) of why an object cannot accelerate to infinite speed. My equation provides an approximate first improvement on Newton's approximation. Your link provides a better view and your equation is more accurate as v approaches c. Dbfirs 12:47, 31 March 2011 (UTC)

No, for parallel acceleration and velocity you are out by two powers of gamma. Thus even to a first order correction in power series your correction is out by a factor of 3. That is big, that is like me responding to a question "what is pi?" with the answer "3" and claiming I thought they just wanted an approximation. Besides this your answer also does not support your claim that you were merely intending to provide a first approximation (never mind discussion as to in what way this is a first approximation), if you were providing an approximate answer you should have stated this. There is no benefit in proliferating some kind of lie on some assumed and awkward notion that the OP couldn't handle the truth. —Preceding unsigned comment added by 92.20.201.71 (talk) 02:19, 1 April 2011 (UTC)

But gamma is very close to 1 until v gets close to c, and the correction term is divided by c squared (a very big number). The questioner was wondering why Newton's even wilder approximation didn't hold. I do agree with you that it was a mistake on my part to ignore the other term in differentiating (by the product rule) the more general form of Newtons Law: Force = rate of change of momentum, where $p={mv \over {\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}\!$ (and another mistake not to use vector differentiation). I apologise for proliferating the misunderstanding. I ought to know better! (In my defence, I would comment that this was the explanation in the text-book from which I learnt about relativity many years ago.) Dbfirs 06:50, 1 April 2011 (UTC)

Antimatter, antigravity, spacetime, retrocausality, and antispace

Warning: Risk of cosmological brain spasms or nonexistent headaches

Hi. Does antimatter have positive or negative mass? Assuming it has negative mass, we could depict its effect on the curvature of spacetime as a flat sheet as an object causing an upward dent in this fabric from antigravity, rather than a downward dent produced by normal matter. Using this representation, could we conclude that the collision of a piece of matter and antimatter represents the overlapping of a positive and a negative dent, therby causing the two warping areas to collide and annihilate? Would this be similar to standing waves cancelling out each other, in this case each respective object's mass/antimass, and would this send out gravitational waves? Or, would the idea of each having the other object's respective antigravity cause some kind of gravitational repulsion?

Since spacetime is the modern interpretation for interwoven space and time, would antimatter cause negative time to occur in addition to causing a negative gravitational "space-dent"? Could antimatter fuel thus have the capacity for time travel alongside massive propulsion? Also, considering that antimatter produces antigravity as an assumption, would the graviton theory apply to "negative gravitons" or regular gravitons going inward? If a negative and positive graviton were to intersect, what would ensue?

Creating negative time from antimatter would enable backward flow of time, and in fact there is some preliminary laboratory evidence of retrocausality. In this scenario, do the occurence of future events cause past events, or do the un-occurrence of future events un-cause past events to un-materialize? When a forward-time-flowing mass of matter and a negative-time-flowing negative mass of antimatter collide, do their respective time reflections cause the collision to un-occur, or does time stop before each object collides into the other?

From the relativistic view of one object, it would take an infinite amount of time for the other object to approach whereas it takes very little time to an outside observer. Would this be similar to the theory that time stops for objects entering black holes, which is also proposed by the varying speed of light hypothesis? Or, would this mean that in a quantum mechanics sense, the objects have both simultaneously annihilated and stopped their annhilation but neither outcome has taken place due to the lack of an observer? Does that mean that black holes are the unity of matter and antimatter confined so that their produced energy are converted to mass as time stops the explosive reaction and release of rest energy from taking place? Similarly, could this explain the paradox of an object entering a black hole and coming out in the past in a different trajectory as to knock the original object away from the black hole's path so that the original event could never have taken place, by realizing the past post-entrance object as one quantum half of the original object so that they merge and two digressional paths occur?

Could any event in the universe, even for a fraction of Plank time, cause the black hole-type dent in spacetime to reach so infinitely deep that it comes around on the other side ("around" the ultra-dimensions of the universe, even if flat) and connects into itself like an infinite regression wormhole? Finally, would a "dent" made in space by antimatter cause the object to take up negative space, so that its dimensions are, say, -2 cm in diameter (and would this also cause "in" to be an infinite directional dimension similar to "out", which does not end until the edge of space is reached)? Does this potential for anti-spacetime have any potential implications, or does this hypothetical description reduce relevance to cosmological nonsense? Thanks. ~AH1^(TCU) 23:33, 30 March 2011 (UTC)

Replace "article" with "thread": {{Sub-sections}} Magog the Ogre (talk) 00:16, 31 March 2011 (UTC)

Unfortunately, none of what you said has any bearing on reality, since as noted in the Antiparticle article, antiparticles (the constituents of antimatter) have the same mass as normal particles, not negative mass. Truthforitsownsake (talk) 00:18, 31 March 2011 (UTC)

Negative mass (if it existed) would not cause an upward dent in space. An upward dent is the same as a downward dent, because only the intrinsic shape (curvature) matters. Rather, negative mass would cause there to be less space in the middle, instead of more. If you add material in the middle of a sheet, it bulges (up or down). If you remove material, it "pinches". That would be the negative-mass version of those bulgy GR images.

There is nothing physically "anti" about antimatter. Every kind of particle in nature has a mirror image under a certain symmetry (CPT symmetry), and sometimes one particle of these mirror-image pairs is named "anti-" followed by the name of the other. By analogy, the shapes F and ꟻ are mirror images of each other under ordinary mirror symmetry, and we could call the second one "reversed F" (that is its name in Unicode). But "reversedness" is not a property of the shape itself. It just happens that F is more commonly encountered in everyday life, so it gets the simpler name.

I'm not aware of any relationship between VSL cosmology and the idea that time stops near a black hole. -- BenRG (talk) 03:31, 31 March 2011 (UTC)

Also, there's no preliminary laboratory evidence of retrocausality. -- BenRG (talk) 04:35, 31 March 2011 (UTC)

Hmmm... to be clear, in order for negative mass to be possible, you'd have to be able to draw a line that is straighter than straight? Wnt (talk) 04:55, 31 March 2011 (UTC)

No, there's no such thing as a line that's straighter than straight, but there is such a thing as spacetime curvature corresponding to negative mass.

A way to make a crude model of the usual "bulge" is to take a circle of paper, cut out (and discard) a wedge, tape the cut edges together to get a cone, then tape that cone to another piece of paper with a circular hole cut in it (as shown here, but I wouldn't necessarily believe any of the text on that page). To get a model of negative mass you could do the same thing, but adding a wedge instead of removing it. That is, make a radial cut in the circle, insert the wedge you removed from the other circle, tape it at both sides, then try to tape the edge of that to a circular hole in another piece of paper. This doesn't work nearly as well as the cone, and it's not clear that the concept of negative mass actually makes sense, but I think that those two facts are unrelated.

(It may seem like you're "removing space" when you make the cone and "adding it" when you make the anti-cone, but it's actually the other way around, in the following sense: if you draw a circle on the flat paper around the cone, the area of the paper inside the circle is larger than you'd expect from the circumference; and in the case of the anti-cone it's smaller.) -- BenRG (talk) 08:33, 31 March 2011 (UTC)

The connection between VSL and time stopping at the event horizon in addition to the experimental evidence of retrocausality are both found in Discover magazine. Perhaps an ultra-straight line would be an anti-geodesic? ~AH1^(TCU) 13:07, 31 March 2011 (UTC)

There's no such thing as an ultra-straight line or an anti-geodesic.

The retrocausality article is this one, I guess, which describes some sort of delayed-choice experiment. These are old news, and aren't evidence of retrocausality. The VSL article is this one, I guess, from which I learned that João Magueijo does believe that black holes are frozen stars, so I stand corrected. But João Magueijo is not a reliable source of information about the real world.

Please understand that Discover has to come up with something to entice its readers every single month. When there's no real news about cosmology or quantum mechanics—which there usually isn't—they have to manufacture something. Real evidence for retrocausality or VSL cosmology would change the whole course of theoretical physics. Anything that appears solely in Discover isn't news. -- BenRG (talk) 01:24, 1 April 2011 (UTC)