Wikipedia:Reference desk/Archives/Science/2012 August 10

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August 10

Metal sorting

What is the best way of extracting and sorting metals from scrap on a small scale? The process I currently use, is to take scrap, which I suspect to contain metal, pulverise it using a mortar and pestle. Followed, by roasting the grind in an oven. The oxidised grind is then solubilised in concentrated hydrochoric acid, followed by fractional electrolysis.

How do I separate the deposited metal from the gold sputter-coated glass electrode? Plasmic Physics (talk) 06:12, 10 August 2012 (UTC)

Waht do I do about the unreacted precipitate, how do I reprocess that? Plasmic Physics (talk) 06:17, 10 August 2012 (UTC)

Well, the most obvious first step is to use a powerful magnet to pull out any ferrous metals. But what exactly is the mix of "scrap" you are dealing with ? StuRat (talk) 09:49, 10 August 2012 (UTC)

Anything, including electric components, screws, bits of wire, tin cans, broken lightbulbs, bottle caps... OK, so grinding may not always be appropriate. Plasmic Physics (talk) 10:14, 10 August 2012 (UTC)

As proof of concept, I extracted some copper from an old brass coat-hook. For that, I used a graphite electrode. It was not a good idea, it disintegrated because of eletrolytic intercalation. Plasmic Physics (talk) 10:23, 10 August 2012 (UTC)

As you can tell, scrap includes non-metal components. Plasmic Physics (talk) 10:37, 10 August 2012 (UTC)

I don't understand the part about unreactive precipitate. Do you mean the metal that didn't dissolve in the HCl i.e the residue? Why are you using HCl rather than aqua regia? I think StuRat's suggestion to remove ferromagnetic things with a magnet is a good start. Based on your above list you will have iron, zinc, gold, copper, tin, lead, tungsten and more. The lead and gold wont dissolve in HCl. Nitric diluted 1:5 with water will dissolve Pb with heating, but not the gold, so that might give you some ideas for treating the HCl leach residue. Platinum electrodes are probably better, though obviously hugely expensive. If you change to a new electrode every time you change the voltage then you can remove the deposited material from the platinum with different acids i.e nitric for lead, aqua regia for gold, HCl for zinc, etc. You could also use electrodes made from the metal that you're removing. That would probably be ideal. How pure are you expecting the results to be? — Preceding unsigned comment added by 112.215.36.180 (talk) 10:59, 10 August 2012 (UTC)

A lab scale ball mill or IsaMill may also save your arm falling off from all that grinding with the mortar and pestle. 112.215.36.171 (talk) 11:22, 10 August 2012 (UTC)

Noted.

The unreactive residue would be a combination of silica, HCl-resisting metals, basically anything that reacts poorly with HCl. I'm not using aqua regia, because I don't want to strip my gold coated electrodes. I could switch to graphite electrodes when I'm reprocessing the residue, allowing me to use aqua regia. I'll make my own nitric acid the old fashioned way. Another point, what about sodium - all that electrolysing is bound to enrich the electrolyte in sodium, is there a way of negating this? Plasmic Physics (talk) 11:40, 10 August 2012 (UTC)

As far as purity goes, simply eliminating non-metal components would suffice, although I want to try and isolate the metals with purity from each other as well. Plasmic Physics (talk) 12:47, 10 August 2012 (UTC)

Some of the large scale methods may work too. For example electrostatic attraction, bubble floatation - the metal will stick to bubbles and your silica will not. Density separation, panning in a gold pan. Using aqua regia will probably result in your ingredients costing more than the metal you will recover. Graeme Bartlett (talk) 12:55, 10 August 2012 (UTC)

Sure, they may work, but equipment I don't have is needed. Which part of aqua regia is so expensive? Remember, I make nitric acid myself. Plasmic Physics (talk) 13:14, 10 August 2012 (UTC)

Panning will probably not work, since I'm working with a coilloid. Plasmic Physics (talk) 13:46, 10 August 2012 (UTC)

Perhaps some useful tips here: http://www.finishing.com/191/49.shtml Sounds like a topic that likely has been discussed on the http://www.sciencemadness.org/talk/ forum as well, maybe worth a search. Ssscienccce (talk) 14:28, 10 August 2012 (UTC)

Doyère, binomial authority for Milnesium tardigradum and so on

Hi all.
"Louis Michel François Doyère" appears to be binomial authority for Milnesium tardigradum and a bunch of other critters. (See also: Louis Michel François Doyère at Wikispecies.) Can't find enough on my own to start an article for him. Your help, please!
--Shirt58 (talk) 12:11, 10 August 2012 (UTC)

There's a scrap more (with at least one reference to hunt down) on French Wikipedia: [1] 129.234.186.45 (talk) 14:05, 10 August 2012 (UTC)

Danke sheyn, 129.234.186.45. --Shirt58 (talk) 11:55, 11 August 2012 (UTC)

Incremental cost of second Curiosity-like rover

What would the approximate incremental cost of a second Curiosity-like rover be? I assume that the total cost of the Spirit / Opportunity pair was significantly less than twice what the cost of developing, constructing, launching, and operating a single rover would have been. -- 203.82.95.201 (talk) 13:29, 10 August 2012 (UTC)

$5 Billion, because you first need to build the Chemistry and Metallurgy Research Replacement Facility to make the plutonium. Hcobb (talk) 14:38, 10 August 2012 (UTC)

Strictly speaking, you don't need that facility (which doesn't exist yet, mind you), you just need some way of getting the plutonium-238. There are lots of ways to do that for far cheaper than $5 billion. The Multi-Mission Radioisotope Thermoelectric Generator used in Curiosity was not produced there (from what I gather, it was produced by Idaho National Laboratory), and there's no reason to assume the next one would need to be, either. The off-the-shelf cost for the MMRTG is quoted as $100 million, so it's not very cheap. I don't know what the full system costs are, but they would be somewhat misleading, given that it is not a single-use facility. I wonder if the OP isn't asking about the marginal cost, though — what making the next rover would cost without all of that spending on R&D. --Mr.98 (talk) 17:13, 10 August 2012 (UTC)

Yes, I suppose I did intend to ask about marginal cost. I see that Incremental cost redirects to Marginal cost where it says:

For discrete calculation without calculus, marginal cost equals the change in total (or variable) cost that comes with each additional unit produced. In contrast, incremental cost is the composition of total cost from the surrogate of contributions, where any increment is determined by the contribution of the cost factors, not necessarily by single units.

Frankly, that definition leaves me clueless as to what incremental cost is. I understand what follows:

For instance, suppose the total cost of making 1 shoe is $30 and the total cost of making 2 shoes is $40. The marginal cost of producing the second shoe is $40 - $30 = $10.

What about a simple example for incremental cost? -- 203.82.95.201 (talk) 19:37, 10 August 2012 (UTC)

The one rover concept for ExoMars which was based on a MSL Landingsystem and a MSL type rover with a mixed ESA NASA Payload had a prise tag from JPL of 1 billion. The MAX-C rover was nor built because it was not possible to build it for less than 2.5 billion. So for me this looks like JPL would like to have 1 or better nearly 2 billion for a rebuilt MSL rover. The plutonium for one more mission and the the new sterlig driven RTG are already availabel. The one thing I hear about JPL is that they never fly a successfull mission twice.--Stone (talk) 18:11, 10 August 2012 (UTC)

Yea, and that never seemed wise to me. The Spirit/Opportunity were so successful, they should have just sent a dozen more of those (perhaps upgrading the scientific instruments, but not changing the rest). But, since they've now gone and spent billions on the next generation, I would hope, if it's successful, they will send multiples of those, instead of again starting from scratch. Their failure to reuse successful designs is a big part of the reason why NASA launches are becoming prohibitively expensive, and they must now look to private enterprise to do things in a more reasonable way, since they refuse to do so. StuRat (talk) 19:32, 10 August 2012 (UTC)

JPL is not only building like the good old Ford model T, but they have people developing things and those people have to have a job because you need them later. The only way to make the thing work is provide JPL with a new development project every few years to ensure money for 2000 people. This is not a science question and never will be but a business question. This is true for ESA too. --Stone (talk) 21:11, 10 August 2012 (UTC)

In that case, put them to work on something which really does need a new design from the ground up, like a manned mission to Mars. We need a faster propulsion system, better shielding, fewer g's, a much larger payload, etc., all of which requires a complete redesign. Or, if that's too ambitious, start with the new manned mission to the Moon. (Since we haven't gone to the Moon for 4 decades, a new design there is OK.) StuRat (talk) 02:44, 11 August 2012 (UTC)

Estimating cost for spaceflight is so complicated that NASA Johnson Space Center has an entire division dedicated to the task. NASA's Office of Cost Estimation has an entire website full of references, and a complete textbook, Cost Estimating Handbook. If you care to see real numbers, NASA's FY2013 budget is available online. There are also proposed budgets for future years, including projections for future Mars expenditures. The Planetary Science projections contain entire chapters discussing tradeoffs and budget considerations for Mars missions. Notably, "a $226.2 million decrease from the FY2012 estimate," ... as Mars Science Laboratory "entered Operations phase and requires much less funding indicative of significant reductions in the workforce." This means that building a second rover is not in the budget. The project budget breakdown does indicate specific line-item costs that correspond directly to "building" a rover; but you can't just buy a rover - even if you magically found the money for it. You have to appreciate that this reported "rover cost" is part of an entire program, corresponding to a schedule, a strategy, and an operational budget. And, the entire Mars program has suffered a projected 37% budget cut - so, there's no money to buy a new rover, and no money to launch it, and no money to hire a workforce to design, manage, or operate it. Even if you got a rover for free, you couldn't put it on Mars in this funding environment. Nimur (talk) 20:59, 10 August 2012 (UTC)

NASA got two Hubble Telescopes for free and they pay to store them. They do not have the money to make them part of a mission and pay for launch and ground support. --Stone (talk) 21:11, 10 August 2012 (UTC)

Back in the old days it was pretty common for the US to do two interplanetary probes about the same time, e.g. Mariner 1 &2, 3&4, 6&7, 8&9, Viking 1&2, Voyager 1&2, Pioneer 10&11. The main reason for failure in those days was the rocket. Bubba73 ^{You talkin' to me?} 02:17, 11 August 2012 (UTC)

For the interesting history, see For the interesting history, see Mariner program, Pioneer program, Viking program, and Voyager program. Bubba73 ^{You talkin' to me?} 04:01, 11 August 2012 (UTC)

@Stone, are you saying there are two more Hubbles that simply haven't been launched? (!!!) Please provide a link. μηδείς (talk) 04:10, 11 August 2012 (UTC)

They were given two mirrors (mirrors only) by the US military. Bubba73 ^{You talkin' to me?} 04:21, 11 August 2012 (UTC)

(UK) approx. inch and a half long insect with a long thin sting, wasp colours but not a wasp shape

I've literally just come into the house out of the way of a bizarre insect the likes of which I've never seen before. At first I thought it must be a hornet, but it does not resemble a wasp aside from its black and yellow bands (large bands, only a few on its entire body), it's definitely not a European hornet which to look at is just a larger wasp.

This thing's wings were large and folded over its back like a beetle, but it was longer and thinner more like a wasp/honey bee, it was shiny rather than furry. Its antannae (sp?) were bright yellow, as were it's legs, these appendages looked like luminous fishing wire, quite thick and bright yellow. Its sting was long and thin and was at least a couple of centimetres if not longer, compared to a wasp it was much longer in comparison to its body. The body itself did not (from a respectful distance) look visibly segmented, it was a slightly angular sausage. Its shape was quite similar to the naiads image in the mayfly article. When it flew it was steady but quite slow, sort of menacing like you get in those killer insect films.

Anyway, I'm surprised to put it mildly after popping into the back garden and finding this thing sunning itself on the patio table, when it started lazily flying around me I had the sudden urge to run away squealing :S Can someone suggest what this thing might be? Someoneanother 15:18, 10 August 2012 (UTC)

Most likely a hoverfly, I think -- some of them have wasp-mimic coloration. However I always have trouble understanding verbal descriptions of insects, and there are many species that mimic wasps. Looie496 (talk) 16:13, 10 August 2012 (UTC)

We do have plenty of hoverflies, but the only species I know of around here are the little thin ones which are much smaller than any bee and don't resemble them physically. This thing had droopy antennae which reminded me of those giant african millipedes, the way the legs and antannae were also a different colour to the rest of it also reminded me of those. This thing was huge, the only native insects I've seen of that size have been (what I assume to be) European hornets and the larger species of grasshoppers. The way the thing was put together spoke more of scorpions and cockroaches than beetles, bees and flies. It is very difficult to describe it but it was weird. It may only be pretendy-poisonous and be wearing those colours to mimic as you point out the hoverflies do, but that prong sticking out of the back of it was thick and very nasty looking. Someoneanother 16:58, 10 August 2012 (UTC)

Ichneumen wasp, probably. The "sting" is an ovipositor. --TammyMoet (talk) 16:52, 10 August 2012 (UTC)

Ah, I'm not familiar with these, but looking at the image there it shares the same droopy antennae and nasty stingy thing. The body shape was more linear but the image in that article shares the same sort of.. well, loathsome appearance. It was pretty in its own way but while dressing up as a wasp and having that ovipositor protruding from the back it looked like the kind of thing you'd never want to be locked in a room with. I'll keep my eye out in case it comes back for a photo. Thanks to you both. Someoneanother 17:01, 10 August 2012 (UTC)

Here's one that's dressed up like a wasp: http://en.wikipedia.org/wiki/File:IC_Ichneumon.JPG 109.99.71.97 (talk) 17:50, 10 August 2012 (UTC)

The colours were certainly proper wasp colours like that, but it looked quite different. It seems very likely that it was one of these wasps, I just wish I got a photo of it :( Need to sort out a camera for these weird encounters. Someoneanother 21:45, 10 August 2012 (UTC)

Have you browsed a google image search for "ichneumonon" [2]? (Ichneumonid [3] has different hits) Also- those long ovipositors are no risk to you. They are solely for boring into wood, which can take hours! SemanticMantis (talk) 22:56, 10 August 2012 (UTC)

User:Someone another might be made of something softer than wood, and perhaps therefore doesn't want to risk it! I saw "ovipositor", and, classical education and all that, thought it just wanted to lay some eggs for breakfast, not bore into people! :) --Demiurge1000 (talk) 03:35, 11 August 2012 (UTC)

Ichneumon wasps are not loathsome. They're the ninjas among wasps! :( They're one of the most skillful users of chemical warfare in the insect world, with most species famous for the polydnavirus that have actually symbiotically merged into their DNA, becoming biological weapons. Every cell in the wasp has a copy of the virus from birth and every time they lay eggs they also deliver the virus which infect the host and suppresses its immune system, leaving the baby wasps free to eat the unfortunate host alive. Like other parasitoid wasps, they're also famous for their "mind control" methods. For example, Ichneumon eumerus (which I should make an article on) starts ant civil wars, so they can enter the anthills unharmed and lay their eggs on the lycaenid butterfly larvae inside (who incidentally also use their own chemical allures to trick ants into thinking they're baby ants and thus feed and protect them).

And like most parasitoid wasps, the majority of ichneumon wasps do not sting. Particularly those with very long ovipositors. As mentioned, wasps which have them use those for boring through plant material (see sequence of pictures in the Ichneumonidae article), substrate, or directly through the body of their hosts (see pictures in our Braconidae article). The long ovipositors in the latter are because some caterpillars are covered with defensive hairs (which probably evolved as a defense against the wasps in the first place). However, members of the subfamily Ophioninae among ichneumonids have shorter ovipositors, and those do sting. But only in self-defense. Also it's not dressing up as a wasp. It is a wasp.-- OBSIDIAN†SOUL 05:13, 11 August 2012 (UTC)

Sorry for my poor choice of words there, I did like its look and find the information that you and everyone else has provided here very interesting and I'll be reading up further to quash my ignorance. The 'loathsome' comment comes mainly from its appearance reminding me of that poisonous African millipede. I foolishly watched a youtube video of one killing a small snake, which made the lizard part of my brain go "ew ew EW". That the wasp reminded me of that was enough to make my toes curl. Can I ask, as you're obviously very interested in this area, how is it that this wasp, which is large and has a wasp's markings and what appears to be a wicked stinger (I know better now, but others without knowledge of them would probably think the same), can be native here yet not be the sort of thing that would get mentioned when people see them? If it was some tiny beetle or fly they'd be easily missed, but it was a big one! Someoneanother 22:49, 11 August 2012 (UTC)

Sorry I think I also misread your earlier post (was up way past bedtime). I thought you were agreeing it was an ichneumon wasp, heh. I'm biased though, since I like the creepy-crawlies.

Anyway, as 90.197.66.109 showed below, they do get asked. Just usually in some out-of-the-way insect identification or UK wildlife forums or something. Are you sure it wasn't a sawfly though? Sawflies are distinctive enough in that they have thick "hips" unlike ichneumon wasps which have typical very slender "wasp waists". Is that what you mean by "not visibly segmented"? If it's not U. gigas, then have a look at other horntails. Horntails have characteristically elongated sausage-shaped abdomens. And they too do not sting despite the fearsome looking needle-like ovipositors. They use those serrated ovipositors as drills (the origin of their common name "sawfly") when they lay their eggs inside plant material. Ironically, their biggest enemies are ichneumon wasps who drill through plant material to find their larvae. Particularly the giant ichneumon wasp (Rhyssa persuasoria) which might also be a possibility as they're also common in the UK.-- OBSIDIAN†SOUL 05:28, 12 August 2012 (UTC)

From the side view in the photograph the Urocerus gigas looks too waspy in shape (conical abdomen), but the top-down view photos in the Horntail look closer in terms of body shape, they also have the standard yellowjacket colours, so while none of them directly match what I saw, it may well have been a sawfly. Looking through the photos of ichneumon wasps provided above, this one's legs are of a similar type and also have the neon effect colouring, the one I saw's legs and antennae were like yellow highlighter pen, a different colour to the yellow on the body's bands. Its antennae were curled at the end and very mobile, looking a lot like the one on the right of this image, if that's of any use. Someoneanother 00:41, 13 August 2012 (UTC)

It wouldn't have been something like one of these, would it? I gather from repeated questions on the Ask A Biologist website (the UK-based one, not the US-based one of the same name) that they're being sighted more often in the UK, possibly due to changing climate {The poster formerly known as 87.81.230.195} 90.197.66.109 (talk) 15:12, 11 August 2012 (UTC)

I don't think so, the links SemanticMantis has provided have provided a few images which, with different aspects added together, would look something like the species I saw. I'll try to do that tomorrow, sorry for the late response to everyone's posts and the less than brilliant descriptions, things are a little er.. interesting IRL and I'm not 100% ATM. A new phone (probably within a week) with a camera means in future everyone can see for themselves rather than have my blathering :S. Someoneanother 22:49, 11 August 2012 (UTC)

Year we would live on mars.

Who and when would we arive on mars? Would we be able to move there and live? What year is this possible? — Preceding unsigned comment added by 205.142.178.36 (talk) 15:46, 10 August 2012 (UTC)

Please read Manned mission to Mars. Looie496 (talk) 16:02, 10 August 2012 (UTC)

thank you so much that was a great read. — Preceding unsigned comment added by 205.142.178.36 (talk) 17:08, 10 August 2012 (UTC)

It's going to depend greatly on what you mean by "living there". If you mean send a person to live there for a few weeks during a mission, we might be able to do that in a decade or so, if we decide to do so. If you mean establishing a permanent Mars base, with supplies ferried from Earth on a regular basis, that would be more like a couple decades, if we wanted to fund that. If you mean establishing a self-sustaining Mars base, that would take several decades. If you want to terraform Mars so people can live outside, without space suits, then we're talking about centuries. StuRat (talk) 19:22, 10 August 2012 (UTC)

"Centuries" is extremely optimistic. If every country in the world devoted its entire industrial capacity to terraforming Mars, the project would still take thousands of years. Keep in mind that 150 years of the entire world's CO2 emissions have not even managed to raise Earth's temperature by a degree, and have only raised the CO2 concentration from 280 to 395 ppm, less than 1/10000 of the entire atmosphere. --140.180.5.169 (talk) 06:50, 11 August 2012 (UTC)

Have you heard the phrase "work smarter, not harder"? The way to terraform Mars isn't to devote enormous resources to it. We need to come up with a way to do it efficiently. That someone may be able to come up with an efficient method in a few centuries isn't particularly optimistic. --Tango (talk) 14:27, 11 August 2012 (UTC)

Perhaps a large comet which passes nearby could be redirected to slam into a Mars polar cap, vaporizing the water there and in the comet, thus kick-starting the greenhouse effect. StuRat (talk) 19:19, 11 August 2012 (UTC)

Somewhere there is a terraforming roadmap which suggests ~800 years is the best case scenario given very optimistic assumptions about frozen water, genetic engineering, and engineered microbe viability under absurdly punishing dry, freezing, and low-light conditions. But several thousand years is probably much more reasonable given what we know about martian water today. "Never ever" is also very much in the realm of possibilities, probably many times more likely than 1,000 years or less. 75.166.207.214 (talk) 01:47, 12 August 2012 (UTC)

The only way I could imagine that we will never be able to terraform Mars is if we kill ourselves off first. After all, given enough time, we could enclose the entire planet in domes and change the atmosphere however we want. (How about a dome with helium in it, so we can all sound like cartoon characters ?) StuRat (talk) 03:22, 12 August 2012 (UTC)

Living longer with a transplanted heart

Could you live longer than expected with a transplanted heart? It's true that auto-immune medicines pose a disadvantage, but on the other hand maybe you are a sedentary 65 and get a heart of a young and healthy motorcycle rider. OsmanRF34 (talk) 18:29, 9 August 2012 (UTC)

Wrong desk -- but I'll leave it to you to move the question. Looie496 (talk) 18:32, 9 August 2012 (UTC)

I think he is coming from a technical stand point not a natural medical stand point.

There is a huge amount of risk involved in a heart transplant, so, if you are asking about a hypothetical sedentary 65 year old with no sign of heart disease getting a heart transplant "just in case", that would lower their life expectancy. However, at some point on the future, when we can do the surgery with far less risk, and can grow spare, compatible hearts in a lab, then it might actually make sense to do such a preventative surgery. StuRat (talk) 04:01, 10 August 2012 (UTC)

I'm asking in a real-life scenario. I know that hearts for transplants are scarce and transplantations risky. OsmanRF34 (talk) 16:59, 10 August 2012 (UTC)

Um, the whole point of a heart transplant is that the recipient is likelier to live longer with one than without. Are you suggesting it as elective surgery? μηδείς (talk) 18:55, 10 August 2012 (UTC)

I think he's asking about heart transplants for older people with no signs of heart disease. People do sometimes die of undiagnosed heart problems, so the idea isn't completely absurd. However, at present, the risk of the surgery and rarity of donor hearts would make this unwise. StuRat (talk) 19:16, 10 August 2012 (UTC)

People only die of undiagnosed heart problems because we don't routinely screen for those problems. It would be easier to just start a screening programme than to replace everyone's hearts... --Tango (talk) 14:40, 11 August 2012 (UTC)

Agreed, although some heart problems may not be possible to diagnose and others may seem to be minor issues which don't require medical intervention, while they really do. StuRat (talk) 19:15, 11 August 2012 (UTC)

Reformulating the question: given a 65 years old (and given a general life expectancy of 15 years for 65 year old people), who gets a heart of young healthy motorcycle rider. On the one hand, heart transplants may decrease your chances of hitting that general life expectancy, but you are also getting a healthy and young heart, which improves your life expectancy. Considering his advantages and disadvantages, can he maybe surpass that general life expectancy? OsmanRF34 (talk) 21:27, 10 August 2012 (UTC)

The question is hugely speculative. I don't think you can say we're anywhere near the point where heart transplants will be elective, like, say, stomach stapling, which I have seen go very bad for two acquaintances, one who has lifethreatening nutrition problems, and the other who became addicted to pain killers leading to a very tragic divorce. The article talks about survivors. μηδείς (talk) 21:52, 10 August 2012 (UTC)

The question is not hugely speculative. It's about comparing the life expectation of an average 65 years old to the life expectation of a 65 years old with the heart of a 20 years old. Who is going to live for a longer time? The latter has advantages and disadvantages, which are more important? OsmanRF34 (talk) 23:56, 10 August 2012 (UTC)

The unaltered 65 year old is, on average, going to live for a longer time. --Demiurge1000 (talk) 03:30, 11 August 2012 (UTC)

It is speculative because we don't have evidence of what happens to healthy people who are given heart transplants, because it just doesn't happen. It may be that, if you aren't already in a very frail state, the risks of a heart transplant are very low, but we don't know because we've never tried. You can get an upper bound on how useful it would be by looking at causes of death, though. Is it only deaths caused by heart problems that you are going to prevent. Cardiovascular disease is one of the biggest killers in the developed world, but I think it is usually the vascular bit rather than the cardio bit that is the problem (ie. veins and arteries, not the heart). Another problem is simply that there aren't enough motorcycle accidents to supply all the hearts needed by people that will die in a few months without one, so we can't start giving them to healthy people unless organ cloning is developed. --Tango (talk) 14:40, 11 August 2012 (UTC)

Time manipulation

If i could manipulate time in a mannor of freezing atoms could i move the atoms using my own force(i am not frozen)? — Preceding unsigned comment added by 205.142.178.36 (talk) 17:07, 10 August 2012 (UTC)

The real laws of physics don't allow "manipulation of time" of the sort you describe. You would have to invent fictitious laws of physics that would allow such a thing, then figure out what the fictitious laws say about your question. -- BenRG (talk) 17:41, 10 August 2012 (UTC)

Haven't physicists been able to hold atoms stationary, by lowering the temperature and then using a laser or some such to stabilize the position? Haven't they been able to move individual atoms around? Edison (talk) 18:20, 10 August 2012 (UTC)

Laser tweezers are used to lower kinetic energy of individual atoms - which reduces their net motion. It does not "freeze time;" it merely reduces the test-particle's energy (and hence, the amount and velocity of movement). Nimur (talk) 18:56, 10 August 2012 (UTC)

Stopping time is easy. Just jump into a Black hole. Hcobb (talk) 18:25, 10 August 2012 (UTC)

I am asking this cause im righting a comic book about a man who has the ability to manipulate time and i want it to work out in a scientific way. — Preceding unsigned comment added by 205.142.178.36 (talk) 20:25, 10 August 2012 (UTC)

Since time manipulation is impossible in the way you describe, you'll have to resort to what everyone else does: Either gloss over it completely, or throw scientific sounding words out there so people think you know what you're talking about. Someguy1221 (talk) 20:54, 10 August 2012 (UTC)

In particular, "stasis field" is a fairly standard scientific-sounding phrase that's used in fiction to describe such things. But if you want to use something new, it's fairly easy to create scientific-sounding nonsense, such as "localized temporal inflection point". Red Act (talk) 21:48, 10 August 2012 (UTC)

You can't make it scientific, so throw that goal out. The best you can do is make it self-consistent. For that, you'll have to come up with a model for how the time is frozen. Make the model as convenient to the plot as you need it to be. --Mr.98 (talk) 20:54, 10 August 2012 (UTC)

This is a much-explored sci-fi area. One trivial example was My Favorite Martian, where the Martian could point at someone and make them "freeze". That wasn't a stoppage of time, it was merely suspended animation. Seems to me The Twilight Zone had a story about that kind of thing. One variation on this idea sounded more plausible, the Star Trek episode about a group of people who somehow operate at an accelerated rate, so the Enterprise crew is not literally frozen, but they move very slowl (in relation to the accelerated group). ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:51, 10 August 2012 (UTC)

Only acceptable answer to a world with imaginable rules: they can be what you imagine them to be. Most SF don't care about it being tangentially possible, and that doesn't make them less attractive as fiction. OsmanRF34 (talk) 00:00, 11 August 2012 (UTC)

Electromagnetic waves, please help me!

When I was in high school (not much long ago, like 2 years ago), when teaching about electromagnetic waves, they just showed the direction and magnitude of the electric and magnetic field only along one line, which is in some sense a 1-dimensional picture of EM waves, while I wanted to know what the field lines look like. Needless to say, I was not satisfied. So what I did was visualizing a simple version of an antenna. Which was a negative and a positive charge oscillating and passing through each other when they meet. so then I could visualize what it looked like in 2D and 3D and I was very happy with it(http://en.wikipedia.org/wiki/File:Electromagnetic_Waves_visualization.png) (I didn't show that the "loops" get "bigger" as they move away, also, it's just the electric field...). The problem is, whenever in textbooks they want to explain an effect concerning EM waves, they use the simple one dimensional version (and of course that's the right thing to do!) and I just can't help thinking "what does this mean in 3D". I had the problem when learning about crystallography, and the problem still remains (i.e. I gave up), but what I have a problem with now is polarization of light. well, I first started by visualizing the polarized light itself in 3D (because again, the pictures are always in 1D) and I could get a rough idea by imagining two point charges rotating around each other, and of course http://www.youtube.com/watch?v=naaeDJLcxgs helped a lot to, so I think it looks kinda like Fusilli pasta, but I still can't get it fully.So, after loads of unnecessary information, here are my questions:

1. Reading about chirality, once it said that normal light contains waves oscillating in all planes, even if it's monochromatic. well, wouldn't the oscillations cancel out and there will be only one plane left? they're vectors after all! (forget about visualizing that!)

2. Does the electric/magnetic field lines of a light emitted from an ordinary source look like what I drew? if not, what does it look like? is it messy?

3. When light passes through an environment with chiral molecules in it, it polarizes. Well, assuming we are using an electromagnetic wave as simple as what I drew, how do the torus-like wave fronts of an ordinary wave turn into the (probably?) fusilli like shape of a polarized light? I can't visualize that.

Whenever I see the EM waves shown that way, I understand the explanations, and I just feel that what I learned is incomplete, mainly because I can't visualize it in 3D. So my last question is that is there an easy way to visualize it, or should I just give up?--Irrational number (talk) 19:47, 10 August 2012 (UTC)

Electromagnetic waves are complicated fields: they have two vector values for every point in space. Visualizing two vector-fields, overlaying each other, in 3 dimensions, is not easy. Recognizing, understanding, and correctly visualizing the time-varying nature of the fields is even more difficult. This is exactly why electromagnetic physics is taught using equations and mathematical formalism. The way the fields behave don't need to look right; they need to satisfy the correct form of Maxwell's equations (whatever that ends up looking like). With a computer, you can plot the field strength and render a vector representation, but for any nontrivial cases, the resulting drawing is very difficult to interpret. You can develop better intuitions about the geometries of electrodynamics by working lots of problems, and to some extent even by experimenting in a lab, but I wouldn't stress out if you're having difficulty visualizing the fields under dynamic conditions. Nimur (talk) 21:45, 10 August 2012 (UTC)

1. In terms of photons (and light fundamentally is made of photons), non-polarized light is made up of photons of different polarizations; in terms of electrical and magnetic fields, the polarization varies depending on location (on pretty small length scales).

2. E.g. incandescent lamp light (or similar thermal light sources, e.g. a glowing piece of coal) is produced by many atom-scale emitters due to thermal motion of electric charges, so it's more or less a superposition of many such dipole waves, and it's certainly messy.

3. Your dipole waves are linearly polarized. The plane of polarization is formed by the symmetry axis of your antenna and the position of the observer (a line and a point off the line define a plane). If you want circular polarization, take 2 waves with linear polarizations perpendicular to each other and one shifted by a quarter of the wavelength with respect to the other... this superposition is a circularly polarized wave.

Icek (talk) 23:03, 10 August 2012 (UTC)

psoriasis

how did they treat psoriasis before modern medicine? 1800's and before--Wrk678 (talk) 22:59, 10 August 2012 (UTC)

If you mean before modern drugs now currently used for psoriasis, I don't actually know, but since nobody else has answered, I can suggest a couple of likely candidates:-

I've had it for 50 years. 50 years ago a doctor prescibed an "ointment" which was actually pitch in a solvent, to be smeared on. It was messy, revolting, but it sort of worked a bit.

Psoriasis tends to go away in ultraviolet light. So, a pre-modern treatment could have been to go outside and expose the rash to the sun. In fact, some doctors still advise that today, with a caution against sunburn & skin cancer.

I have over the years found some home remedies that work to a certain extent, but we don't give that sort of advice here. Wickwack120.145.191.48 (talk) 03:03, 11 August 2012 (UTC)

The Old Philosopher, Eddie Lawrence, once said somethng about flagellation as a cure for psoriasis. Odds are good that he was joking. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:22, 11 August 2012 (UTC)

That would make them psorer.-- OBSIDIAN†SOUL 03:27, 11 August 2012 (UTC)

My mother's psoriasis was more or less completely relieved by traditional Chinese herbal medicine. It involved boiling a broth of, among other things, cicada shells and tree bark. She then drank the broth. It smelled god awful, but did the trick. 112.215.36.179 (talk) 04:57, 11 August 2012 (UTC)

I can anecdotally confirm the ultraviolet thing. At age ~28 my scalp was in a frightful state. I stopped wearing a hat every day, and it quickly cleared up. —Tamfang (talk) 20:39, 12 August 2012 (UTC)

Just wondering, is there any evidence that psoriasis was diagnosed 200+ years ago? (I was going to say, did people suffer from psoriasis 200+ years ago, but realised I meant something different.) --TammyMoet (talk) 08:50, 11 August 2012 (UTC)

The answer to that, is yes/no/maybe/maybe not. That's because psoriasis (a modern term) is actually a collection on various sorts of skin disease for which a cause is unknown, and that may or may not be related. The word psoriasis, root-wise, means "itchy skin" but most forms do not itch at all, or only itch due to inappropriate attempts to treat it. It is not at all unlikely that in earlier times, a bad case of psoriasis got diagnosed on the basis of appearance as early leprosy, which it is not. Diagnosis even today is problematical. In my case, 30 years ago I saw a skin specialist, who cut out a piece of skin and sent it to the lab. The lab's reply was essentially "It's abnormal, but we don't know what it is". The specialist's conclusion was "I don't know what it is, but it is probably a form of psoriasis." More recently, my regular doctor decided that with the advance of time, it was worth while getting another specialist opinion. The new opinion was the same as the first. Wickwack120.145.191.48 (talk) 10:54, 11 August 2012 (UTC)

In pre-modern medical times, most skin diseases and ailments were lumped together under the catchall term "leprosy". Today, the definition of Leprosy is confined to a specific skin disease, being Hansen's Disease, but prior to modern disease theory, just about everything was called "leprosy" without distinction. Leprosy#History covers some of the earlier definitions of leprosy, including classification of less serious infections (tinea fungal infections, such as athletes foot or jock itch or ringworm) with the more serious. The Wikipedia article specifically mentions psoriasis as being an affliction commonly confused with leprosy in pre-modern times. Tzaraath contains some interesting information on ancient categorization of skin diseases as well. As to how people were treated; it may be likely that people with severe psoriasis would have been treated as other lepers were: like a leper: ostracized or shunned from their community, often they were segregated into leper colonies; that article also mentions that many skin diseases were miscategorized as leprosy. --Jayron32 18:44, 12 August 2012 (UTC)

Beetles common to England seem to come in very specific sizes?

I'm in southern England, and every few weeks, one's home is politely invaded by a single specimen of a black beetle about half an inch long. (I am, naturally, very confident that it's not the same individual coming back time after time.)

These beetles are particularly noticeable because they move around the house by walking everywhere quite slowly (including up several flights of stairs), and have difficulties with stability that result in them regularly getting stuck upside down on their backs. They react to this by waving their legs in the air vigorously in order to attract nearby humans, who will eventually get bored of watching, and therefore use a credit card to help the beetle get the right way up again.

Apart from this curious co-evolution with credit cards (how do the credit card manufacturers benefit from the relationship!?!), the strange thing about these beetles is that they are always the same size. You never see one that's a bit smaller or a bit bigger, as far as the untrained eye is concerned.

Pondering this problem, I remembered some distant fragments of high school biology, and considered the fact that perhaps these identikit beetles were instars of a particular beetle species, and that perhaps these beetles only undergo ecdysis at particular body sizes that look roughly the same size. Perhaps the preceding instar is too small to open my letterbox and climb through it (or however they get in?!?), and the succeeding instar is very rarely reached due to the instability problem. (Perhaps some humans are less friendly to stranded beetles than I am.)

I was even more enthused with this random theory when, while walking to my local Indian restaurant, I discovered, dragging itself apparently painfully across the sidewalk, an immense black beetle that looked identical to the standard issue beetles that I normally encounter, except for its size and being somewhat plumper. Now, it could have been a completely different species - for example a rhinoceros beetle, which would explain the slight proportional increase in girth - but that wouldn't explain why I'd never seen younger, smaller versions of rhinoceros beetles.

Is it plausible that instars might explain all these beetles looking roughly the same size to me? Is it plausible that the huge beetle was an individual of the same species that had managed to survive through a couple of extra instars? --Demiurge1000 (talk) 23:15, 10 August 2012 (UTC)

Yes. You are correct in that this is an instar, but it's the last one. While insects periodically undergo ecdysis as larvae and [usually] grow larger with each molting; once they reach adult stage, they do not molt anymore and hence are stuck to whatever dimensions their exoskeletons hardened into. Insects in this stage are known as imago. There is no "younger" and "older" once they reach this stage in terms of size, the misconception is largely because most people treat adults and larvae as different animals due to their very different appearances and life habits (e.g. treating caterpillars as pests, but ooh-ing and aah-ing at butterflies).

Insects with softer bodies and longer lifespans as adults may still increase in size depending on factors like food consumed or gravidity (termite queens being one of the best examples). But beetles, obviously, have one of the thickest exoskeletons among insects. Therefore, when you see similar-looking adults which differ greatly in size, chances are they are different species. However, some species do exhibit morphological variation among subspecies, or even within populations (and of course, there's sexual dimorphism as well).-- OBSIDIAN†SOUL 23:33, 10 August 2012 (UTC)

Ah, yes, my imaginative mind ignored the fact that all the common British wasps I've seen are approximately the same size too. Although everyone knows that's because they were made in The Wasp Factory. Right, back to the drawing board.

Oh, what was the big beetle then? An escaped pet? --Demiurge1000 (talk) 02:51, 11 August 2012 (UTC)

Oooh. That's one of those books by Banks I'll never read. Mostly because he wrote it without the "M." and it doesn't have spaceships. Anyway, if you were six years old and happened to be my niece, I'd tell you it was the daddy beetle. But chances are it's female and probably eats your house beetles for breakfast.-- OBSIDIAN†SOUL 03:16, 11 August 2012 (UTC)

So the same species as the others, then? If so, it probably got the idea from the big mummy alien trapped under Antarctica in a rather bad film. --Demiurge1000 (talk) 04:42, 11 August 2012 (UTC)

Hate cross-universe films. Anyway, seriously? Most probably not. A lot of beetles which belong to the same family look identical to our layman's eyes, differing only in size or something just as arbitrary, but they're really not. In your case, since you compared it to a rhinoceros beetle, I'm guessing your beetles were both scarabs?-- OBSIDIAN†SOUL 05:29, 11 August 2012 (UTC)

And yes, your hypothesis on Coleoptera and credit card coevolution is one of the greatest evidences of evolution. Scientists have discovered recently that credit cards may have ultimately evolved from sticks used to poke at strange terrifying bugs by neanderthals. They evolved to their present day form after a population bottleneck when early modern humans decided to put one of the strange terrifying bugs in his mouth and discovered they tasted just like chicken (raw chicken guts that is). They survived in scattered human populations which still found the strange terrifying bugs gross, evolving to various forms like pipes, canes, umbrellas, clubs, swords, and dowsing rods. All of which retained a form or another of their commensalistic relationship with overturned beetles. One branch developed into strangely dorsoventrally flattened forms with partial radial symmetry and metallic exoskeletons. Though they were not as effective in overturning beetles as their later more specialized descendants.-- OBSIDIAN†SOUL 23:53, 10 August 2012 (UTC)

They just squished them instead? How does that contribute to the symbiosis?!? --Demiurge1000 (talk) 02:47, 11 August 2012 (UTC)

A lot of symbiotic relationships originated from predation or parasitism. For example, our own cells still keep enslaved mitochondria they swallowed eons ago, which still refuse to give up their own DNA. Listen closely and you can hear them demanding civil rights.-- OBSIDIAN†SOUL 03:16, 11 August 2012 (UTC)