Wikipedia:Reference desk/Archives/Science/2014 July 17

Science desk
< July 16	<< Jun | July | Aug >>	July 18 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 17

Can Magnesium or Nsaid drugs inhibit muscle Metabolism?

Someone Anaerobically exercises his Limbs... After the workout his muscles keep to contract and he start's having Doms. Can taking Magnesium or Nsaid drugs (To ease this Dom's Pain) actually damage the Anabolic process he aimed to achieve by the workout? Thx. Ben-Natan (talk) 08:26, 17 July 2014 (UTC)

Fixed your link. --50.100.189.160 (talk) 08:47, 17 July 2014 (UTC)

?Ben-Natan (talk) 10:21, 18 July 2014 (UTC)

I'm sorry, we cannot give medical advice. --ColinFine (talk) 15:54, 18 July 2014 (UTC)

It's not a question for a medical advice - It's a question about Metabolism (particularly in Muscles). Ben-Natan (talk) 16:50, 18 July 2014 (UTC)

Is osmium blue?

Copper#Physical appears to state that Os is one of the four coloured metals (the others being Cs, Cu, and Au). Greenwood & Earnshaw on the other hand state that Cs, Cu, and Au are the only three coloured metals. So is Os coloured? If so, could anyone explain why it is coloured? Double sharp (talk) 13:30, 17 July 2014 (UTC)

There are several pictures of it on the osmium article (and another at [1]). It's variously described as "blue–white" or "blue–black". To my eye, it appears mostly like a generic meta, silvery with maybe a tint of a color, not as obviously colored like copper, gold, and highly pure cesium seem. DMacks (talk) 16:16, 17 July 2014 (UTC)

Judge for yourself the Osmium powder in this video which appears black in inert argon, but is said to oxidise to smelly, dangerous Osmium tetroxide in air. 84.209.89.214 (talk) 23:24, 17 July 2014 (UTC)

It's pretty clear that the samples in the article have blue highlights. The article says it is bluish. But is the blue the metal or just the oxide coating? I should add that I'm suspicious that if we are strict enough many other metals will be classified as "colored". After all, visually it seems like you can tell things like bismuth, lead, aluminum, and silver seem just a little different than the lovely metallic shade of something like mercury. But I've never actually looked at polished samples of those in a rigorously inert environment. It'll be interesting to see a good answer here. Wnt (talk) 22:01, 18 July 2014 (UTC)

I found a paper talking about the oxidation of the platinum group metals. Specifically in the case of Os, it appears that it is always covered with a OsO₂ layer at STP, which reacts with air to form OsO₄. As for osmium dioxide, our article says "It exists as brown to black crystalline powder, but single crystals are golden and exhibit metallic conductivity." How was the sample of Os in the PTOV video linked above prepared? If it was exposed to air before being sealed in Ar, then the black may well be the OsO₂ surface coating. It's interesting to note that rhodium's RhO₂ layer is only visible (it looks like a tarnish) when the Rh is heated: maybe this is also true for Os, which would explain why the colour of the metal (as opposed to the brown-black colour of OsO₂) is only visible under special conditions (most images I found online do not show this bluish colour).

WP:ELEM/PIC has a periodic table with small element pictures in each cell, which may help improve comparison. To me Hf looks a bit coloured (blue? green?), and Zn, Ga, Re, and Cd seem to show a slight tinge of blue. Yb seems to show a slight yellow tinge, as do Ir, Gd, Ni, and Nd. But I'm worried that some of these might be image artifacts, and the colour differences may be so slight that I'm imagining colour gradients that aren't there.

I imagine the mechanism that causes some metals to appear coloured would be the same as the mechanism that makes Cs, Cu, and Au coloured. For example, in Au, the ground-state electron configuration is [Xe]4f¹⁴5d¹⁰6s¹, while the first excited state is [Xe]4f¹⁴5d⁹6s²: the energy required for exciting this 5d electron to 6s corresponds to absorption in the blue region of the spectrum, which we see as a yellow colour. I understand the same effect is operating for Cs and Cu – copper and gold promote an electron from 5d to 6s, while caesium promotes an electron from 5s to 5d. Ni is said on WP to have a gold tinge, and in this case we are promoting a 4s electron to 3d.

It appears that the ground-state electron configuration of Os is [Xe]4f¹⁴5d⁶6s², while the first excited state is [Xe]4f¹⁴5d⁷6s¹. But I have no idea what the energy level is, nor what colour in the absorption spectrum it corresponds to. If Os' blue tinge is real and intrinsic to the metal, then I would think it should correspond to yellow. Does it? Double sharp (talk) 13:38, 21 July 2014 (UTC)

These are complicated issues and there are definitely better-qualified people reading this who should have answered, but since they haven't I'll try my best.

To begin with, the colors of powders and thin films can be anything - often it has to do with diffraction effects rather than intrinsic color. You can tell the thickness of a section of a clear resin for electron microscopy based on which lovely color it is. So it's hard to work with that.

The main thing about metals is that they reflect. The interior of the metal is probably something absolutely beautiful with color if you could see it, but you can't; only the metal salts reveal their color because they are no longer conductors (well, that has something to do with it anyway). The energy levels in the transition group and in high numbered orbitals are close together, which is the reason for the lovely salts. But the presence of free electrons produces an interfering signal that reverses the light (see mechanism of reflection (physics). Only a very narrow region within the skin effect/penetration depth is exposed to the light. The Hagen-Rubens relation links the conductivity of the metal with its reflection coefficient.

I think answers for your question exist, but honestly, I have a hell of a time trying to make heads or tails out of them. For all I know the answer is in [2], but they're studying something far more refined than the color of osmium. I would bet they know what it is though! Wnt (talk) 17:23, 21 July 2014 (UTC)

Rain power ?

It seems to me that a type of hydroelectric power could be generated by using the gravitational potential energy of rain collected on rooftops. The most power could be generated where you have tall buildings with frequent rain. Such power generation would be intermittent, of course, so, like solar and wind energy, being able to sell it back to the electric company to reduce your bills might be the best approach. Does such a system exist ? StuRat (talk) 13:54, 17 July 2014 (UTC)

I suspect that the cost of the system would outweigh the savings. The Pumped-storage hydroelectricity article discussed a few questions above contains this calculation: "For example, 1000 kilograms of water (1 cubic meter) at the top of a 100 meter tower has a potential energy of about 0.272 kW·h (capable of raising the temperature of the same amount of water by only 0.23 Celsius = 0.42 Fahrenheit)."

Large buildings could use rooftop rain collection for Greywater collection, to prevent the need to pump water for toilet flushes to upper stories. The savings in the power bill would be higher than if it was used for generation, and the system would be much simpler. Our articles on related subjets don't have much to say about it - it would be interesting to know if any buildings are using that sort of approach. Katie R (talk) 14:14, 17 July 2014 (UTC)

I'm all but sure it does; my company captures and uses greywater captured via roof collection for warming the freezer floor and then washing out the delivery trucks. We'd probably flush the toilets with it afterwards, but it would be inconvenient to install the extra piping necessary. Matt Deres (talk) 15:09, 17 July 2014 (UTC)

It doesn't seem to be a viable method, if you do the calculations. Looking at this table, yearly precipitation is, depending on the location, at most ~3 meters/year. So one m² of roof surface gets 3 m³/year, which is 9.5 * 10^-8 m³/s. Each m³ at 1000 meters altitude has 1000 kg * 9.8 m/s² * 1000 meter = 9.8 * 10⁶ J of potential energy, so energy output is, on average 0.931 W/m² at 100% efficiency at 1000 meters altitude in a very rainy location. Even the cheapest solar panels will get you a great deal more power output per m². Buildings of more reasonable dimensions (~100 meters high), get less then 0.1 W/m² even without any losses. - Lindert (talk) 14:41, 17 July 2014 (UTC)

Since this system wouldn't preclude other uses of the roof, such as solar panels, I'm not sure that looking at it this way is the right approach. Presumably the infrastructure to drain the water off the roof is in place in any case, with the only additional cost being that of the water turbine(s)/electrical generator(s) at the bottom of the drains. So, the cost of those units should be compared with the value of the electricity generated. StuRat (talk) 16:59, 17 July 2014 (UTC)

A two story house would generate a few cents' worth of electricity per month. It would take centuries, more likely millennia, to pay for a generator. If you factor in maintenance it's a total no go. Googling for "roof hydroelectricity" and such will find people doing it as a hobby, but for anything serious it is a few magnitudes off, cost/benefit -wise. 88.112.50.121 (talk) 23:42, 17 July 2014 (UTC)

Who's talking about a two story house ? I asked about tall buildings, like skyscrapers. StuRat (talk) 02:56, 18 July 2014 (UTC)

Since the kinetic energy in the water derives from the height that the droplets are formed at (ie, where the cloud is at) - it doesn't matter how tall your building is. Collecting water into a big tank on the roof and letting it fall through a generator to ground level would waste the energy in the water at the moment of impact onto the roof. If you can collect THAT energy - then the total of energy gathered by the impact of the water on the roof PLUS the energy gained by releasing it to ground level is the same - regardless of the height of the building. That said, the speed of a falling raindrop reaches terminal velocity eventually - but still, that kinetic energy has to go somewhere - so the friction with the air is warming up the raindrop and you'd have to collect the microscopic amount of energy from the temperature of the raindrop being a fraction of a degree warmer than ambient air. But the numbers simply aren't there...there just isn't enough energy to be had to make it worth building a machine to capture it - and then have the machine sit idle all the time it's not raining hard enough to overcome the internal losses in the machine itself.

But let's consider just the flow of water off the roof of a 400 meter tall building (the Empire State Building, for example)...it has a roof area of 10,000 square meters. The rainfall in New York is around 1.2 meters per year. So 12,000 cubic meters of water per year fall through 400 meters. A cubic meter of water weighs 1000 kg. The total gravitational potential energy gathered by having that water flow through a frictionless pipe to a generator at ground level would be m.g.h which is 12,000,000 . 9.8 . 400 = 48,000 MJ...which is the amount of energy used by a typical US automobile in a year. So adding all of this stuff to the Empire State Building would allow ONE occupant to charge his electric car...assuming the system is 100% efficient and extracts ALL of the energy from the falling water regardless of it's speed and volume. Even a light mist of rain would have to generate energy. More likely, it would be not even half that efficient.

So it's not tremendous amounts of energy. But the real problem is that the energy comes all at once during a heavy rainstorm - then nothing for weeks more. You'd probably find that almost all of the usable water flow would come in a handful of big storms during the year - and your machine would have to have the capacity to work in the heaviest deluges. So you'd need a water turbine capable of generating all the energy that a typical car uses over several months over a period of a few hours. An incredibly rough estimate suggests that this machine would probably be a hundred times more expensive than a car engine - and can't really power a car - and that's using the rain energy from the fourth tallest building in the USA.

Some clever ideas just don't work - no matter how much you think they should. This is one of those. SteveBaker (talk) 05:25, 18 July 2014 (UTC)

RE: "Since the kinetic energy in the water derives from the height that the droplets are formed at (ie, where the cloud is at) - it doesn't matter how tall your building is." I have to disagree with your conclusion here. When it hits the roof it will lose any kinetic energy it had at that point, and I can't think of any good way to capture that energy, except maybe hanging some dirty laundry out and using the raindrops to wash them. So, at that point all that's left is the gravitational potential energy, which is dependent on the height of the roof. Note that it's not necessary to build a tank on the roof, it can flow down the downspouts as it always does. And cars are rather energy intensive devices, how about if we instead use the energy to power the adjacent apartments, or sell it back to the energy company, as I suggested ? A nice benefit of powering apartments is that they might be able to disconnect from the grid during storms, when power spikes are a risk. Also, you might not want to use equipment large enough to handle the maximum flow rate at the downspouts, just have a bypass for the excess, when the flow rate is too high.

Also, at my Mom's house, I installed a system to collect rainwater in a rain barrel, then slowly release it. This is to prevent a flooding problem whenever it rains. (Her drainage system just can't keep up with the rainfall.) Now this is at ground level, where the pressure is too low to be useful, but I could imagine a similar system in use atop tall buildings, where water is currently collected in tanks to prevent overtaxing the sewers during storms, then slowly drained. If such a system exists, then we could add a very small device to convert that gravitational potential energy to electricity, at a steady rate, at the bottom of the downspouts. StuRat (talk) 16:51, 18 July 2014 (UTC)

Using your Empire State Building calcs, I get 13333 Kwh, and I pay about $0.15 per Kwh, so that's $2000 a year. If we want the device to pay for itself in 5 years, we could thus spend around $10,000 for the device. Is that enough to pay for such a device ? StuRat (talk) 17:08, 18 July 2014 (UTC)

That calculation has been done before. - ¡Ouch! (^{hurt me} / _{more pain}) 10:10, 18 July 2014 (UTC)

That's using the relatively low pressure of a municipal water supply, not quite the same as the pressure from a high building. StuRat (talk) 16:36, 18 July 2014 (UTC)

True. And oddly, the xkcd guy totally missed that it was hot water, which should have opened a whole range of lunatic schemes up to him. Wnt (talk) 21:51, 18 July 2014 (UTC)

True. But my calculation isn't. It's still a non-starter. SteveBaker (talk) 23:48, 18 July 2014 (UTC)

In the high limit (say, the Burj Khalifa), a building can introduce a factor of 20 (~800m translate into about 20 times normal tap water pressure), but then, rain does not provide water 24/7. The Burj might be the low end of the spectrum when it comes to water quantity.

The kinetic energy of raindrops doesn't look promising; they don't seem to fall faster than from, say, the 2nd floor. If friction keeps them from accelerating any further, that would translate into less than another 10m, no matter how high the clouds are. - ¡Ouch! (^{hurt me} / _{more pain}) 06:32, 21 July 2014 (UTC)

What technically quest been bestly?

If world university science of humankind been began at simple to implex in all, what technically quest been bestly, which start at first from implex to simple technical or around another?--Alex Sazonov (talk) 16:51, 17 July 2014 (UTC)

That question is hard to understand. I'm guessing you meant "What are some examples of technology which has changed from simple to complex and from complex to simple". If that's what you meant, then almost all technology progresses from simple to complex. But we can probably find a few examples that moved in the reverse direction. One thought is space ships, sent to the Moon and other planets, which, when they carried humans, had to be more complex than later ones carrying a robotic cargo. One of my favorite examples of a simple technology which is still in use after thousands of years, despite far more technical solutions existing, is the plumb bob used to create a vertical chalk line. StuRat (talk) 17:02, 17 July 2014 (UTC)

You see StuRat, this is exactly what we're talking about. μηδείς (talk) 17:20, 17 July 2014 (UTC)

I have no idea what you're talking about, as I provided references. StuRat (talk) 17:42, 17 July 2014 (UTC)

Thank you StuRat! In Holly Bible always been sad that God been do all at implexly miracle materia to simplely miracle material, but human mind always been do as human think as from simple to implex. Why human always do around another that God? I seen, that all technically quests always been implex that they always must been do at decide God. As I know a science always been start at implex to simple if a science quest been implex, is it’s right?--Alex Sazonov (talk) 17:55, 17 July 2014 (UTC)

I can think of one example where science has a simpler solution than biology, the wheel. Compared with legs, that's a much simpler system. StuRat (talk) 18:06, 17 July 2014 (UTC)

As I know well the USA always decide now that simple technically decides always been bestly because the simple always been infective, is it right?--Alex Sazonov (talk) 18:11, 17 July 2014 (UTC)

I don't know if it's true or not, but there was a story that the US space program spent a lot of money to develop a pen that would work in zero gravity, while the Russians used a pencil instead. StuRat (talk) 18:19, 17 July 2014 (UTC)

Thank you StuRat. The USSR always been give a simple story technology for world. I been think, what is been always clever, the cognizing the world from implex to simple or around another?--Alex Sazonov (talk) 18:34, 17 July 2014 (UTC)

The story StuRat notes is false.[3] DMacks (talk) 18:37, 17 July 2014 (UTC)

False-ish. NASA didn't develop the Space Pen - but it did cost a private company quite a bit to develop. NASA actually paid an entirely reasonable price for a bunch of them. Moreover, the Russians didn't use normal pencils because the graphite they produce when you write with them floats around in zero-g and gets into the various switches and potentiometers in the controls causing potentially lethal problems. The shavings produced when sharpening a pencil would also be a nightmare to deal with. It's believed that they actually used a form of grease pencil - but those don't write very well on paper. So this is a really bad piece of mis-information, it makes NASA seem like they spent a fortune for something that wasn't needed - when in fact, they spent very little on something that truly WAS needed. SteveBaker (talk) 19:43, 17 July 2014 (UTC)

To make a long story short, the USSR used regular air while the USA used pure oxygen, in which carbon dust is extremely explosive. Even the solid graphite of the pencil and the wood could catch fire. There is only a minor issue in air (with 21% oxygen), and we're talking about the USSR after all (overstatement, though).

One could say, "The USA threw tax money at it and used the Space Pen and pure oxygen, while the USSR threw cosmonauts at it and used a pencil and ordinary air." (Both ended up with fatalities BTW; the Groeningesque cliché of "wave after wave of cosmonauts" is a huge overstatement.) - ¡Ouch! (^{hurt me} / _{more pain}) 10:31, 18 July 2014 (UTC)

Simple-to-complex-to-simple is a little tough to define. For example, consider something like a boat hull. Originally, early boat-makers probably just hollowed out a log to make a canoe or lashed together logs to make a raft...really very simple. Then, as time progressed we got those amazing pieces of carpentry that made 500 ton warships out of interlocking planks, beams, etc during the age of sail - the complexity in the design and implementation was immense. Nowadays, most small boats have a hull formed from a single piece of fibreglass. Arguably, the fibreglass hull is simpler even than a hollowed out log or a log raft...but "simplicity" here depends on the assumption that you don't include all of the work it took to make the glass into thin strands and weave it into cloth - and the chemistry needed to make the epoxy that turns that in to sheets of a solid material. The entire process is vastly complex - but the resulting boat hull is simplicity itself.

It's very easy to come up with things that have become very simple if you don't include all of the infrastructure it took to get you there.

A more extreme example of that would be that I can write a command on my computer, using the smallest movements of my fingertips that will search a repository containing the whole of human knowledge (well, more or less) to find out a piece of information that our ancestors could have spent a lifetime searching dusty old libraries to discover. Is that "simpler"? It's certainly simpler for me! But include everything about computers, the Internet and so forth - and you have the most complex thing that humans have ever produced.

SteveBaker (talk) 19:43, 17 July 2014 (UTC)

Thank you SteveBaker, do you mean that a science knowledge is been always simple but not implex, is it been mean that not never been implex quests in a science, they always been simple?--Alex Sazonov (talk) 20:37, 17 July 2014 (UTC)

Science is often able to swing back and forth between simple and complex. Take the ideas of how the stars and planets move:

• Early astronomers (who believed that the Earth was at the center of the universe) thought that the planets went around the earth in simple, circular orbits - riding around us on crystal spheres.
• But as more careful observations were made, they had to change that idea to have the planets move on wheels mounted inside those spheres - circles around circles...but these ideas had to get more and more complicated to try to fit ever more complicated observed motion to their original simple idea.
• When the really simple idea that the sun is really at the center of the universe was explored, suddenly everything got incredibly simple again - planets moving in circles around the sun makes the explanation very simple again.
• But they don't move in exact circles - the motion is really elliptical...so new math, new equations and more complexity was needed to explain that.
• Newton's theory of gravitation provides an explanation for why the motion is elliptical - and reduced all of the motion of all of the planets known at that time to simplest imaginable gravitational equation.
• But sadly, that isn't quite correct - and the way that the orbit of the planet Mercury gradually shifts can't be explained by those simple equations. It wasn't until the more complex theory of relativity came along that Mercury's orbit could be fully explained.
• Sadly, even relativity doesn't completely explain the motion of stars orbiting distant galaxies - or the motion of the galaxies themselves. For that we needed to invent the concepts of Dark Matter and Dark Energy...so things are getting more complicated right now.
• Many physicists expect that future work will eventually come up with a Theory of everything that will again reduce everything we know about absolutely everything into a single, simple equation. This may be the final end to this cycle - but it may not happen, there is some evidence that the universe simply isn't that simple.

Science is very often a cycle of coming up with a pretty good explanation for what we see in experiments - then finding situations that our explanation doesn't cover - then figuring out a more complicated explanation to cover those exceptions - then realizing that if you think about things in a slightly different way, it gets very simple again.

SteveBaker (talk) 04:44, 18 July 2014 (UTC)

Thank you for you SteveBaker. What was been, in all means a science always been given a implex or a simple decisions, but why in a science always been a implex method of knowledge which always been a science example at all?--Alex Sazonov (talk) 08:08, 18 July 2014 (UTC)

May be a science is been so simple, that a implex method of knowledge not been. May be a God is been a simple miracle and mind of human is been simple too, I’m don’t know what is been better a simple or implex!--Alex Sazonov (talk) 10:07, 18 July 2014 (UTC)

Even, in a simple science always been a implex method of knowledge, because implex method of knowledge in a science always been more scientifically, than simple method of knowledge, that’s why a science is not been even simple!--Alex Sazonov (talk) 05:44, 19 July 2014 (UTC)

Electricity - Blue colour?

Hi, why is current or electricity depicted in blue or purple color always? are they blue really? if so, why? thanks. — Preceding unsigned comment added by 122.174.34.155 (talk) 19:26, 17 July 2014 (UTC)

Electricity is the flow of electrons...not the electrons themselves - but their movement. So the concept of color doesn't apply. It's a bit like asking "What color is speed?" or "What color is the wind?". The depiction as blue probably comes about because sparks that are made by electricity jumping a gap through air are blue. A spark is the most obvious visual image of electricity - so that presumably explains this idea. But no, electricity has no color. SteveBaker (talk) 19:46, 17 July 2014 (UTC)

For a discussion of the various emission spectra that contribute to the characteristic electric blue color of electric discharges in air, see the article Ionized-air glow. Red Act (talk) 20:00, 17 July 2014 (UTC)

Just to clarify a bit based on Red Act's provided references. The blue or purple color we associate with electric sparks is NOT the color of electricity. It is the color we get from what is called the "emission spectrum" of the specific mix of gases in the air. What happens is that, in a spark across air, electrons in the molecules of air (mostly nitrogen and oxygen) are "excited"; that means they absorb energy (from collisions between the molecules and the free electrons in the "spark"). These electrons are in unstable states, so they have to release the energy they absorbed as a result of those collisions. When the release that energy back to the universe, they do so in the form of photons (light), and these photons are the blue glow. The exact color of the glow depends on the specific material being excited... air produces that characteristic blue glow, but neon gives a red glow, argon is purple, sodium vapor is yellow, etc. For more of a discussion about the mechanics of this "absorb energy-->get excited-->relax-->release photon process, see Bohr model. --Jayron32 21:54, 17 July 2014 (UTC)

And just for fun, I'll note that if the air were thinner, you would get yet another different set of colors. TenOfAllTrades(talk) 13:08, 18 July 2014 (UTC)

The presence of metal vapor or ions in an electrical discharge would influence the color (green for copper??). Edison (talk) 19:37, 21 July 2014 (UTC)

IF the added substance's spectral emissivity is high enough, it COULD influence the color, but if not, then the blue light will overwhelm it (e.g. sodium would probably turn the spark yellow, but potassium won't turn it violet because its emissivity is not high enough). 24.5.122.13 (talk) 00:10, 22 July 2014 (UTC)