Wikipedia:Reference desk/Archives/Science/2012 February 16

= February 16 =

Flogging
What is the chance of survival after flogging as a corporal punishment? I know in countries like Malaysia or Singapore flogging is common and 10-12 lashes are generally given. But there are extreme examples where a person is given the sentence of 50 or more lashes, especially in countries like Saudi Arabia. For example the Wikipedia article on Mazen Abdul-Jawad says he is still living in prison after getting 1000 lashes (I believe the information is wrong, if he's living, the sentence was probably not carried out). What is puzzling me is that how a person can survive after getting such a large number of strokes? As far as I know, the skin is ruptured after 2-3 strokes, and flesh is exposed after 5-6 strokes. So the later strokes will directly hit the gluteal muscles, resulting in the muscles being mutilated. So it can be deducted that 50 or more strokes will completely destroy the muscle or even expose the bone. In that case the person will simply die from shock, or from blood loss. So how is it possible for someone to survive after 50 lashes or more? But I've seen examples where people are sentenced this way, and they are still claimed to be surviving. --SupernovaExplosion (talk) 05:28, 16 February 2012 (UTC)


 * Flogging practices can vary considerably from country to country. Your statements apply to the most severe type of punishment, as practiced in Malaysia. And even then 50 strokes won't completely destroy the muscle, because the cane is much narrower than the buttocks and it won't hit the same spot every on every stroke. In Malaysia and Singapore, prisoners never receive more than 20-25 strokes at once. (Even 20 at once would be an extreme punishment that is reserved for rapists and major drug dealers.) There are videos on youtube showing this kind of punishment, you can easily find them if you have the stomach for it.


 * When you read about people getting 100 lashes or more, like in Saudi Arabia, that's a very different kind of flogging. In Saudi Arabia, flogging is not intended to inflict permanent damage (it is meant to be humiliating rather than painful). According to most reports, it is done through clothing, and the person who does the flogging is required to hold the Quran under his arm, to keep him from hitting the victim with full force.--Itinerant1 (talk) 08:55, 16 February 2012 (UTC)


 * I bet a Koran held under the arms of many people, while performing floggings in Saudi Arabia, in the summer, must stink badly of BO. StuRat (talk) 20:04, 17 February 2012 (UTC)


 * (ECs) A brief and unreferenced initial answer that I'm sure others will improve on, but from logic and memory . ..
 * The amount of damage will depend on how hard the blows are administered, and with what. If the intention of the punishment is to cause pain rather than permanent maiming and/or death, then the punisher will likely temper the blows appropriately.
 * In the case of high numbers of blows, the sentence need not be carried out in one session. The recipient may be given, say, 50 lashes, taken away to heal for days or weeks, then given another 50 and so on until the total is reached.
 * {The poster formerly known as 87.81.230.195} 90.197.66.94 (talk) 09:03, 16 February 2012 (UTC)
 * The risk in taking that approach is that the guy might get to liking it. ←Baseball Bugs What's up, Doc? carrots→ 13:56, 16 February 2012 (UTC)


 * Thank you guys for your replies. I had no idea of these. --SupernovaExplosion (talk) 13:12, 16 February 2012 (UTC)

Black holes
What would be the diameter of the event horizon if all the known black holes that exist were clumpped into one singularity, assuming that no additional mass from surrounding matter was available, or far enough away to not get pulled in? — Preceding unsigned comment added by 165.212.189.187 (talk) 17:54, 16 February 2012 (UTC)


 * The mass of the observable universe is 3*1054 kg. The Schwarzschild radius for a black hole is r = 2GM/c2.  Note that the radius of the black hole is directly proportional to its mass.  So, for instance, if you only care about the 5% of the universe that is observable baryonic matter, reduce your final calculation to 5%.  If you further want to estimate that half of that is in black holes, reduce another 50%.  Regardless, the answer is "big". &mdash; Lomn 18:36, 16

February 2012 (UTC)

Not asking if all matter in known universe was in one singularity, just the matter currently in black holes that we can observe.


 * We're pretty sure Sagittarius A* is a black hole (though there's a chance it's something more exotic), and the same goes for things like Cygnus X-1 and V404 Cygni. The trouble is that Sagittarius A* is the supermassive black hole at the centre of the galaxy, so it's far far far heavier than any other black hole in the galaxy, weighing millions of times more than the sun (some studies say 1 million, others say 4 million), so even if all the other black hole candidates in the galaxy were smashed into it, you'd barely change its size at all - adding black holes that weigh 3 or 4 solar masses will do nothing to a 1,000,000 solar mass black hole. If we're going by black holes we can't observe directly but are fairly certain exist, there are almost certainly more supermassive black holes in the universe - pretty much one per galaxy - so if there is on average, one in each galaxy in the observable universe (~170 billion, according to our article), and they have the same mass as Sag A* on average, that means that all the supermassive black holes in the universe would make a supermassive black hole roughly 1x1021 metres across (about 100,000 light years, almost exactly the same size as our galaxy). If we assume most super massive black holes are bigger (Andromeda's is ~110–230 million solar masses, Messier 87 has one that's about 6-7 billion solar masses), then that'll be a fair bit bigger. If, as a rough stab, we say super massive black holes weigh about 1 billion solar masses, we scale everything up by a fact of 1000, and our black hole is 100,000,000 light years across, 1000 times the size of our galaxy, and big enough that it would reach most of our neighbouring galaxies too. Smurrayinchester 23:16, 16 February 2012 (UTC)

iodine
will iodine react with copper — Preceding unsigned comment added by 64.38.197.211 (talk) 18:59, 16 February 2012 (UTC)
 * See the Wikipedia article Copper(I) iodide. 99.141.7.172 (talk) 19:50, 16 February 2012 (UTC)
 * No, that article doesn't answer the OP's question. The article only proves that the two elements appear in the same compound; but according to that article, it isn't made by reacting metallic copper with elemental iodine.  I don't have an answer to the OP question yet, but neither does that article.  -- Jayron  32  22:56, 16 February 2012 (UTC)


 * Yes it will if you put copper foil and iodine in a test tube and heat it up with a balloon on the end of the test tube. it gives you copper iodide--92.28.76.237 (talk) 01:09, 18 February 2012 (UTC)

chaos and indeterminacy
is the unpredictability in chaotic system unpredictable in a "practical" sense or is it indeterminate and unpredictable at a fundamental level as some believe some quantum physics phenomenon are? I mean could a hypothetical "god" who knows everything about the initial state of a chaotic system predict its behavior til the end of the time? Also I have a question about what do we mean when we say that small particles behave in a probabilistic way, does it mean that:
 * 1.the electron is everywhere at a given time with different probabilities? As saying it does not have a definite position.
 * 2.the electron is at one place at a given time but it is more probable to be found at certain regions, in other words, it spends more time in a specific region, but it's just in one place only at a given time
 * Or is it just a matter of quantum physics interpretations and no one actually knows? I've heard the first one from some physicist (and I actually kinda like it!) and the other one from other physicists... please answer all of my questions!--Irrational number (talk) 19:03, 16 February 2012 (UTC)


 * For your first question about chaotic systems: see chaos theory which says that these systems are deterministic, meaning that there is no 'randomness' or stochasticity in the dynamics. So, if one says "weather systems are chaotic, so long-term predictions are impossible", they are making a statement about practical limitations stemming from the positive Lyapunov exponent, which is the rigorous mathematical concept behind the butterfly effect. Now, as to an omniscient being, yes, it could predict all behavior of that system, which is, in effect, an entire universe unto itself. By this I mean to avoid getting into issues of models vs. reality. In the world of a particular chaotic system, all future states are determined solely by the initial conditions and the equations. Does that make sense? SemanticMantis (talk) 20:31, 16 February 2012 (UTC)


 * so it's not fundamentally unpredictable, it's just that we can't do it... well maybe I was too excied by "the secret life of chaos" BBC documentary :(. Now I'm waiting for my next question...--Irrational number (talk) 20:35, 16 February 2012 (UTC)
 * Chaos theory is plenty exciting. Maybe I should backpedal a bit. The limitations of prediction are inherent to the system, it is not something that will go away with better technology or engineering, in this sense, a chaotic system is "fundamentally unpredictable". The development of chaos theory gave very strong evidence that we will never be able to predict the weather more than a few days out, or the populations of organisms (e.g. logistic model). Both of these are rather important to human well-being, as well as fascinating from a basic science perspective. There is a reason Robert_May,_Baron_May_of_Oxford got knighted for his role in this; these results were quite shocking in their day. Don't get bogged down by "god could know all future states of a chaotic system", that's really just a small part of it ;) SemanticMantis (talk) 21:14, 16 February 2012 (UTC)


 * Irrational number - You are asking two very different questions here. A chaotic dynamical system is a type of mathematical model with certain somewhat surprising properties. But it is a deterministic model, so an omniscient god would know precisely what state the system was in at all future times just from observing its initial state exactly. On the other hand, quantum mechanics is a physical theory that very accurately describes the interactions of real world objects and particles. The answer to your "where is the electron" question is that most physicists believe that when it is not observed, the electron is everywhere at once with different probabilities - there are no "hidden variables". The probabilities are encoded in a wave function which evolves in a completely deterministic manner. However, when the electron is observed the wave function "collapses" and the electron is observed to be in a certain state or region in space - but the wave function collapse is stochastic, not deterministic. Of course, this thumbnail sketch begs the question of just what counts as an "observation" ... Gandalf61 (talk) 09:10, 17 February 2012 (UTC)
 * I have heard about that...some say it's about consciousness or something like that, and some say it's interaction...--Irrational number (talk) 13:14, 17 February 2012 (UTC)

silver
How likely is it that this ring

http://www.overstock.com/Jewelry-Watches/Sterling-Silver-Ring/3322779/product.html?cid=123620

is actually made of sterling silver it seems for the price that it would be plated silver do they legally have to say whether it is solid or plated silver? — Preceding unsigned comment added by 92.48.194.170 (talk) 19:18, 16 February 2012 (UTC)
 * This site quotes the cost of sterling silver as $1.00 per gram. As long as the ring weighs less than about 10 grams, they're making a hefty profit; and at 17 grams they'd break even.  It's quite likely the ring weighs less than that.  And AFAIK, if the ring is not solid silver, they need to use a word like "plated" or "clad" to describe it.  So it is quite likely solid sterling silver.  -- Jayron  32  20:07, 16 February 2012 (UTC)
 * I agree, I'm pretty sure it would be solid. I have never heard "sterling silver" applied to plated items. Silver isn't that phenomenally expensive. And whoever heard of a plated silver ring? Talk about crappy... 81.159.111.172 (talk) 20:27, 16 February 2012 (UTC)

Distance formula to stars
I want to know all the possible distance formula to calculate the distance from the Sun to any stars out there in the universe. Give me the explanation enough about the formula. Example:
 * $$ M = m - 5 ((\log_{10}{D_L}) - 1)\!\,$$. M = absolute magnitude, m = apparent magnitude, d = distance in parsec.
 * Give me the formula and explain as above will really help me. Thanks a lot!Pendragon5 (talk) 21:37, 16 February 2012 (UTC)


 * See the cosmic distance ladder. There are many ways to calculate astronomical distances, depending on the nature of the object and the distance range (AU's? light years? billions of light years?).  --140.180.39.75 (talk) 22:19, 16 February 2012 (UTC)

Few questions about the second law of thermodynamics

 * $$\eta_{\text{max}} = \eta_{\text{Carnot}} = 1 - \frac{T_C}{T_H}$$

Are the units for this equation in kelvin? Also how does one go about proving that any engine (even fuel cells and other non-heat engines) must produce waste heat? Does this equation still apply? ScienceApe (talk) 22:31, 16 February 2012 (UTC)


 * Kelvin, or any other thermodynamic temperature scale with a 0 at absolute zero (eg. Rankine scale). It involves the ratio of two temperatures, so any conversion coefficient gets cancelled out by the division. The temperature scales you can't use are ones where the zero is in an odd place, since that effectively adds a constant to both temperatures, messing up the ratio. ($$\frac{T_C}{T_H} = \frac{aT_C}{aT_H} \neq \frac{T_C + x}{T_H + x}$$) Smurrayinchester 22:45, 16 February 2012 (UTC)