Wikipedia:Reference desk/Archives/Science/2009 April 16

= April 16 =

Ionic detox
Recently, a co-worker met with an alternative health practioneer and participated in an "ionic foot bath." He described all of the ickey things coming out of his feet (including what appeared to be "live" worms. Ever the skeptical one, I did some investigating. Here on Wikipedia, the closest thing I could find was an article on detoxification foot pads. Using Google, I found a plethora of info (all promoting ionic foot baths!). So, here is my question: Since there is no scientific evidence to support the claims of ionic foot baths, what is really happening in the wather that makes it look like things (including worms) are being drawn from the body via the soles of the feet? —Preceding unsigned comment added by 209.161.212.185 (talk) 03:35, 16 April 2009 (UTC)


 * With a little googling you can find accounts of people who run the "ionic baths" without putting their feat in and the water still turns murky. It's a trick. It's been mentioned on The Amazing Randi's site several times. here's the most recent mention.
 * The live worms are an interesting touch, but once you acknowledge that it's a hoax, then it's easy to use slight of hand to add some of those tiny worms that you can buy to feed your Betta fish.
 * In general the idea that there are numerous common "toxins" build up in your body and must be cleansed is new age nonsense. If you've got a healthy liver and a pair of healthy kidneys, most of your toxins are being taken care of. (And, if not, all the foot baths in the world won't save you.) APL (talk) 04:49, 16 April 2009 (UTC)
 * Here are some YouTube videos. Here.  On closer examination, this seems to be similar technology that is used in saltwater etching (Scroll down), except instead of removing metal from an electrode to create an artistic pattern, you're removing metal from an electrode so that the waste metal will darken the water and create a "toxic"-looking effect.
 * I'm also less convinced that there were actual live worms, now that I've read about it more. Perhaps tiny particles of metal held together by magnatism or electric charge would move around in a lifelike way? APL (talk) 05:06, 16 April 2009 (UTC)
 * There is absolutely no doubt that this (and those damned stupid foot-pads) are a total scam. The adverts for the foot pads actually make me laugh:  "Just as the leaves of a tree draw toxins out of the air and expel them through their roots - so the Kinoke foot-pads...yadda, yadda, yadda"...EXCUSE ME?!  Since when do trees absorb toxins through their leaves?   Trees don't expel ANYTHING through their roots.   Actually, they soak up stuff through their roots and expel it (well, water and CO2) through their leaves!  And just because a tree does it (or not) why would that make a difference to humans...we don't even have leaves or roots!  Gah!  Evil bastard scammers with annoying TV ads.  Argh!  Anyway - once you accept that it's a scam - you have to ask how those things got into the water.  I presume that if you were observant and skeptical during the "treatment" you could spot the moment when these things were dropped into the water by the practitioner - perhaps they were inside the 'healing crystals' or whatever else was placed into the water?   Perhaps they were concealed inside the water recirculating mechanism (or whatever it uses).  Perhaps the scammer 'palms' them (as a magician palms a playing card or a coin) and slips them into the water at some point.  For sure there are no worms in your feet!  Ask your co-worker to look at his/her feet and see if the holes from which the worms emerged are visible?  No?  No holes?  Did the worms teleport through the soles of the feet?  If the government isn't going to enforce trading standards and medical practitioner licensing laws against these people then it's up to everyone to be super-skeptical of any of these kinds of claims.  Mostly they don't stand up to any inspection at all.  I really wish I had the time to go to some of these places - take the treatment - spot the scam and sue the evildoers for fraud and practicing medicine without a license.  We're gradually sliding backwards into the Dark Ages - and with all we know and understand - that's just ridiculous.  SteveBaker (talk) 12:51, 16 April 2009 (UTC)
 * I don't think that you could "spot the moment when these things were dropped into the water by the practitioner". I'm pretty sure that the murkiness of the water is actually rust, or other material from the electrodes. They are consumed by the "ionic bath" process and need to be replaced on a regular basis. (This adds a nice 'don't sell the razor, sell the blades' aspect to the scam.)
 * They sell these machines (at about $1000!) for home use, and they produce the same effect when operated by the end user.
 * Of course, live worms aren't going to come out of an electrode. So if there really were live worms, they must have been added by slight of hand. A bit over the top, if you ask me. If I were working this con I would have just stuck with "toxins". APL (talk) 15:40, 16 April 2009 (UTC)
 * Hmmm - perhaps these "worms" are something like dried out Sea-Monkeys that could be inside whatever stuff they sell you to put into the water?  Suppose they sold you a large tablet - like the kind you put into your dishwasher - with a capsule in the center that would dissolve and re-animate the dried worms.  They'd probably scare the bejeezus out of the gullible 'mark'!  But you could probably make sufficiently convincing "worms" out of all manner of inert materials that would expand and look suitably yukky. SteveBaker (talk) 20:36, 16 April 2009 (UTC)produce
 * Well, I suppose you could do that, but there'd be some setup involved. SeaMonkey "instant life" packets take about 24 hours to come to life. I can't find any evidence that it's ordinarily done. None of the videos of the devices (Either the credulous ones, or the debunking ones) show anything that looks like a live worm, though the orange muck seems to eventually coalesce into a few 'floaters' that might look alive if you didn't look too close. These machines involve dunking a pair of electrodes into salt water. The electrodes apparently corrode away, so that explains the gunk in the water. If there were live worms involved, then I'll bet they were put in there by the salesman to try to punch-up the effect of the machine and not part of machine's usual scam. If that makes sense.  Like a vacuum-cleaner salesman who isn't content with ordinary dust, so he hides some graphite in his vacuum. APL (talk) 23:07, 16 April 2009 (UTC)


 * A good rule of thumb: If someone talks about "toxins" but fails to mention what specific substances they mean, you can be 99 and 44/100 % sure they're full of shit. Friday (talk) 15:52, 16 April 2009 (UTC)
 * Yeah. Absolutely.  SteveBaker (talk) 20:36, 16 April 2009 (UTC)


 * Here's a article on the topic. APL (talk) 23:07, 16 April 2009 (UTC)


 * Sadly, while that's certainly what's going on...there was no mention of the worms. These scammers are on to a good deal then...they take one of these foot-spa's (Cost: $15.14 at Walmart) - hook up a couple of electrodes (6" nails ought to do it - that's another $1) and a suitable battery a switch and some wires (maybe another $10) - and sell the thing for $1000.  They'd be making a spectacular profit at $100 - at $1000 it's like printing money!  I could build 50 of these a day by myself with just the tools in my garage.  Then they have the nerve to sell the "refill kits" for $44 plus postage...$55 to you!  Pulling this kind of scam on the American public is like shooting fish in a barrel.  There are times when I really wish I was not such an honest person!  SteveBaker (talk) 00:41, 17 April 2009 (UTC)


 * Minor and off-topic correction for SteveBaker: trees do expel lots of stuff through their roots, primarily sugars destined for the commensal organisms helping them to thrive. It's a fascinating topic, especially when you think about how easy it should be to cheat a tree. It's even vaguely possible that the tree would acquire and pump toxins into the cheating fungi, though I've never seen a single word to that effect. Totally agree though on the other commentary on this scam, my only regret is that I haven't dreamed one of these puppies up! Franamax (talk) 00:51, 17 April 2009 (UTC)

Ideal physical attributes for boxing
In boxing, are smaller or larger fists better (assuming they're on the end of the same arm throwing the same punch)? And what would be the ideal build in terms of height, chest size, reach, muscle mass etc and the relationships between those characteristics? Thanks. 86.8.176.85 (talk) 04:49, 16 April 2009 (UTC)
 * The fist part of your question is easy, the second one is not. When someone (constant weight = same punch power) steps on your hand with high heels (small fists, high relative impact) or Gramps slippers (large fists, low relative impact)... what hurts more? --Grey Geezer 08:01, 16 April 2009 (UTC) —Preceding unsigned comment added by Grey Geezer (talk • contribs)


 * Force equals mass times acceleration - so heavier fists (not necessarily larger ones) with the same exact speed of swing will produce a larger amount of force when they hit something. However, Force equals mass times acceleration - so when you throw that punch, a heavier fist requires more force to get it going fast...or to put it another way...for the same amount of musculature, etc - a heavier fist will end up travelling more slowly than a lighter one - and the benefit of that heavier fist will end up cancelling out.  Now, admittedly - as User:Grey Geezer says - the same amount of force over a smaller area produces more pressure - and therefore (presumably) more pain...hence the reason one stabs people with a sharp knife and not (say) a brick!  As to muscles...the force a muscle can produce is proportional to the cross-sectional area - so if you have two people with the exact same body proportions - but one is twice as tall/wide as the other - then the larger person has EIGHT TIMES the amount of weight to move around - but only FOUR TIMES the amount of muscle force to move it with.   This is why elephants move so slowly compared to (say) dogs...and insects so much faster still.  So we're back to that same Force=Mass times Acceleration problem - if you are smaller, you can move (relatively) faster - but with lighter fists, you need to be faster in order to produce the same amount of force.  But this is all very superficial reasoning - can a larger person train harder?   Can they take more punishment?   Can a smaller person simply dodge all of the big guy's punches so it's irrelevent how hard the big guy can hit?   All in all, it's a very complicated question.  SteveBaker (talk) 12:38, 16 April 2009 (UTC)


 * Larger fists would appear to give an advantage to blocking65.121.141.34 (talk) 14:53, 16 April 2009 (UTC)
 * Yeah - but they're more of a disadvantage when it comes to the running-away-screaming...which is probably higher on my list! :-) SteveBaker (talk) 20:28, 16 April 2009 (UTC)


 * This is as near "ideal" shape for a man as can be designed. Cuddlyable3 (talk) 22:35, 16 April 2009 (UTC)
 * Oh...I feel so inadequate. SteveBaker (talk) 00:28, 17 April 2009 (UTC)

Trolley-bus routes
I noticed that in some cities, trolley-bus routes may be circular or non-symmetrical (e.g., A-B-C and C-D-A even if there are no one-way streets).

Let's say you own a bus company in a small town having a bus terminal (A) and three stations (B, C and D). Let's say your buses are all diesel powered. There can be two routes (there are no one-way streets):

A-B | | D-C


 * Route Clockwise: A-B-C-D-A
 * Route Counterclockwise: A-D-C-B-A

Now if your buses are all trolley-buses. Running these two routes requires that you install TWO SETS OF OVERHEAD WIRES for your entire bus routes.

So you may decide to run one route only and double the frequency (e.g., 10 mins a bus -5 mins a bus).

I guess that if the routes are light capacity (e.g., low population density), trolley-bus companies may have their routes covering more roads one way or circular to increase the number of stations or reduce the length of wires. For example:

A | B |\ C D |/ E | F


 * Route A->F: A-B-C-E-F
 * Route F->A: F-E-D-B-A

On second thought, this logic may not be applicable to railroads. You cannot afford to run a railroad system on a single set of tracks design. If a train is derailed, you can do nothing before the derailed cars are removed.

If you have a subway system, you may want to have at least two sets of tracks because it's much more expensive to dig two smaller tunnels than a big one. One bidirectional underground station is also less expensive than two one-way stations -- Toytoy (talk) 05:26, 16 April 2009 (UTC)

IS MY HYPOTHESIS CORRECT? OR DID I OVERLOOK ANYTHING? -- Toytoy (talk) 07:04, 16 April 2009 (UTC)


 * Sorry, but I cannot find any question :( 122.169.127.46 (talk) 05:35, 16 April 2009 (UTC)

No matter whether you're talking about a trolleybus line, a streetcar line, a subway, or a railway, it's always cheaper to build a single line than a double one. But it also severely constrains your operational flexibility and capacity if you want to operate vehicles in both directions. Loop routes are indeed a possibility for avoiding this issue while building only a single line, but the trouble is that they produce indirect routes, which aren't as good for attracting riders. Passengers want to go more or less directly to their destination, not detour around the sides of a loop. So when transit systems do use one-directional loops, they're typically only small ones, just a few blocks long or wide, usually at the end of a route. Here's an example on a subway line (trains run anticlockwise around the single-track loop), here's one on a streetcar route, and here's one on a trolleybus line, which also includes some other one-way sections due to one-way streets. These examples are in Paris, New Orleans, and Geneva respectively.

Single-track lines are much more common on railways, where distances are long and frequencies may be relatively low, than on urban transit systems such as trolleybuses and streetcars. It is true that a derailment may block the line completely, but derailments are rare (and for that matter, if one happens it may block both tracks of a double-track line). Capacity limits and dealing with ordinary delays are much more of an issue.

It's not always correct that on a subway system "it's much more expensive to dig two smaller tunnels than a big one". It depends on the construction methods. In London, for example, all of the deep-level tube lines do use two separate tunnels for their tracks, and often even for the larger tunnels at stations.

But generally in urban transit, if the frequency of operation on a route is low enough that a single direction is acceptable, it will be operated by buses, which need no tracks or overhead wires. --Anonymous, 08:44 UTC, April 16, 2009.


 * In terms of digging tunnels - the amount of dirt you have to dig and the amount of tunnel-walls you have to erect to make two identical one-track tunnels is (obviously) twice the amount for a single one-track tunnel. But because tunnels have to be circular, making one two-track tunnel requires removing FOUR TIMES the amount of dirt and erecting twice the amount of wall compared to a single one-track tunnel.   So if the cost of removing dirt is high - then making two small tunnels could easily be around half as expensive as one larger tunnel.  Of course there are many other issues involved - such as the size and running costs of your tunnelling machines and the amount of surface disruption caused by your activities. SteveBaker (talk) 12:26, 16 April 2009 (UTC)


 * Factors that favour dual- over single- tunnels for two tracks include 1) the possibility to close a tunnel temporarily for maintenance while keeping a reduced single-track service, and 2) in case of an emergency such as a derailment, fire or chemical spill, the parallel tunnel can be used for access and escape if cross connections are provided. That arrangement has been tested by a number of fire incidents in the England-France Channel Tunnel. Cuddlyable3 (talk) 22:24, 16 April 2009 (UTC)


 * Tunnels certainly do not have to be circular. Some are oval, some have vertical sides and and an arched roof, some are rectangular or close to it, and so on.  Again, it depends on the technology (not necessarily a tunnel-boring machine; less automated techniques were common in the past and are still used for short tunnels, and many transit systems use cut-and-cover tunnels) and on what you're tunneling through.


 * On a subway system, one advantage of double-track tunnels is that since the tracks are close together, they can lead directly into a station that has separate platforms outside the tracks for the two directions of travel, which gives a convenient separation of passenger flows compared to a center "island" platform. Another is that if crossovers between the two tracks (for turnbacks) do not require additional tunneling.  Another is that a single train does not restrict the flow of air through the tunnel significantly, which improves ventilation and also reduces air resistance on the trains.  On the other hand, when circular tunnels are in use, a double-track tunnel requires more height clearance around other things that may be in the ground, and then there are the issues mentioned by the last poster. --00:00 UTC, April 17, 2009.
 * Oval tunnels have one major problem though - you can't use a simple tunnel boring machine to make them because the cutter heads go around in a circle and the tunnel walls have to be lined as the TBM inches forwards. Agreed that oval tunnels are fine when you're doing cut-and-cover though...but then the amount of material you have to remove and replace is large compared to the volume of the tunnel anyway.  As for the air flow argument - I'm pretty sure I read somewhere that the progress of trains though the London underground system is designed precisely so that it DOES move air through the tunnels - and that saves them from having to pump fresh air around the system.  Those trains go so slowly that air resistance probably isn't a large fraction of their running costs.

Streamlining trains is less important than (say) cars and trucks anyway because they only pay the price once for the entire length of the train - compared to each car or truck on a freeway having to pay the energy price again and again. Anyway - we're getting quite a way from the OP's question here. SteveBaker (talk) 00:27, 17 April 2009 (UTC)


 * Again with the boring machines! (Pun intended.) Cut-and-cover tunnels are usually rectangular. Oval ones were probably excavated using a shield or by blasting.


 * It's not correct that trains pushing air through the tunnels provides useful ventilation. The builders of the early tube lines in London HOPED it would, but it turned out they were wrong.  It is correct that streamlining is generally less important for trains than for cars and trucks moving at similar speed, and is generally less important at low speeds, but the situation is different when the train is blocking a large fraction of a tunnel's area.  The newer tube tunnels in London (Victoria and Jubilee Lines) are generally at least 6 inches larger in diameter than the older ones, and air friction is the main reason.


 * --Anon, 07:25 UTC, April 17, 2009.

concurrent queues
at the bank I got a 369, there was someone at 365 but also 500's and 900's. However the bank teller next to me surprised me by offering to tell me when I would come up -- she told me I would be 8th in line. So if her computer shows all three queues as mixed into a single queue order, why keep them separated from each other? Thank you! 94.27.231.11 (talk) 10:17, 16 April 2009 (UTC)


 * I presume that there are multiple ticket-issuing machines with rolls of tickets pre-printed with consecutive numbers. So if you go to the first machine, you maybe get a ticket that starts with a '3' - at the second machine they start with a '5' and at the third machine, they start with a '9'.  The ticket machines tell the computer system when each ticket was issued - irrespective of the number printed on it.  Alternatively - sometimes these machines are set up so that the number tells what kind of service you want - so perhaps if you needed a foreign currency transaction, you'd get a ticket starting with a '9' - and then only the desks that have tellers who are qualified to do foreign currency work will accept those tickets - where every teller can take '3' tickets because those are for general check cashing, etc.   But without knowing how your bank issues those tickets, it's hard to be certain. SteveBaker (talk) 12:19, 16 April 2009 (UTC)
 * I've seen systems that intentionally keep the ticket-numbers non-consecutive (one fast-food place was totally random, some skip around) for no reason other than to keep customers from knowing that they have a long wait ahead for a noticeably higher number than a single linear "now serving #..." queue. DMacks (talk) 14:55, 16 April 2009 (UTC)
 * It is probably done to prevent anyone knowing that they will be served next, allowing them to hover ready to pounce immediately the preceeding customer leaves. Cuddlyable3 (talk) 22:05, 16 April 2009 (UTC)
 * My question here is: why wasn't that helpful teller helping the first customer in the queue? Do they plan this stuff during coffee break? :) Franamax (talk) 00:30, 17 April 2009 (UTC)

Paradox in current through vacuum
please visit the following post in the refdesk : []. Here, some of them are saying that vacuum has zero resistivity. So, if the resistance is zero, for any finite voltage V,

I = V/R so for any value of V, the current would be infinite. It means that infinite number of electrons would be passing through the vacuum at a given time. Please note that the vacuum will cease to be a vacuum if electrons are there but nevertheless, the resistivity will not change as the electrons are not moving at random. But how will the universe contain an infinite number of electrons? --harish (talk) 12:43, 16 April 2009 (UTC)


 * No paradox. If you'll noted, the discussion that gives rise to "resistance = 0" is actually saying energy dissipation is zero.  No energy lost can be equated to no resistance.  In practice, this means that any given voltage can be transmitted at any given current, but this is not a case where division by zero equals infinity. 64.238.255.250 (talk) 13:12, 16 April 2009 (UTC)


 * What does any number divided by 0 equal? If there is no current, there is no defined resistance. Ohms law applies to a conductor with a voltage across it and current flowing through it, nothing more.--58.111.134.75 (talk) 13:16, 16 April 2009 (UTC)


 * Division by zero means that your mathematical model broke down, and you need a better one if you want to know what happens then. — DanielLC 00:58, 17 April 2009 (UTC)

No, R would be infinite, not zero. Another thing is that there will still be a tunnel current, and Ohm's law is not in generally valid in the first place. Count Iblis (talk) 14:34, 16 April 2009 (UTC)

One can "shoot" a charge carrier, such as an electron, through a vacuum. That means a voltage (the shooting force) has caused a certain amount of charge to move from A to B. The charge flow per time is the effective current. The vacuum has neither helped nor hindered the transfer. Because of its non-hindrance to current one may declare the vacuum to have zero resistance but because it does not itself provide any current carrying path for an applied voltage one may declare the vacuum to have infinite resistance. Since the vacuum has not participated, no property of the vacuum, such as resistance, can be deduced from the experiment. Cuddlyable3 (talk) 19:27, 16 April 2009 (UTC)

When an electron strikes the anode in a radio vacuum tube (or similar device), it loses its kinetic energy. The energy will be converted to heat. So there is a power loss.(Large transmitting tubes have heat dissipating fins or may even be water cooled.) Another effect may be secondary emission in which one or more electrons are knocked loose from the anode by the arriving electron. The energy imnparted to the secondary emission electrons will be another power loss. - GlowWoprm. —Preceding unsigned comment added by 98.16.66.104 (talk) 20:57, 16 April 2009 (UTC)


 * For those who care, the article Vacuum permittivity is exactly relevent to this discussion. --Jayron32. talk . contribs  01:22, 17 April 2009 (UTC)


 * At the risk of sounding alittle dense, I have to ask how is the vacuum permittivity related to the vacuum resistivity? I don't see the connection. Dauto (talk) 18:20, 17 April 2009 (UTC)

CO2 production vs Absorbtion
I know there are lists of how much CO2 countries emit, but is there a list of how much CO2 is absorbed (mainly by vegetation) per country? The 'land use' seems to be something completely different. I am trying to make a list of which countries are net CO2 emitters and which are net CO2 absorbers and by how much per capita.--58.111.134.75 (talk) 13:00, 16 April 2009 (UTC)
 * This is poorly understood at present. Lots of CO2 absorption is into soil, and it's quite difficult to calculate the rate at which that happens across all the different kinds of soil in a region. Looie496 (talk) 17:21, 16 April 2009 (UTC)


 * And it will stay poorly understood for a while longer. The OCO satellite mission couldn't get the door open and returned to Earth in a non-optimal fashion. Franamax (talk) 00:20, 17 April 2009 (UTC)
 * Isn't it Algae, i.e. the oceans, which do the really big job? All is one. --Grey Geezer 07:34, 17 April 2009 (UTC) —Preceding unsigned comment added by Grey Geezer (talk • contribs)
 * A stable and healthy eco-system is usually CO2 neutral, i.e. there is no significant net absorption. Most of the CO2 that is consumed by vegetation is released within a short term (weeks to years) when the vegetation rots or is consumed. Only a few geologic formations permanently sequester CO2 by (eventually) turning it into fossil fuels or carbonate rocks over long periods of time. You can draw some CO2 out of the air by planting previously fallow ground, or, to a certain extend, by harvesting plant matter for long-lived products like books and furniture. You might want to take a look at Carbon cycle. --Stephan Schulz (talk) 12:51, 17 April 2009 (UTC)


 * GG, you may be thinking of the oceans physically absorbing the CO2, partial pressure dictates that if you put more of a substance into the gas phase of a system, you will also get more in the liquid phase. Thus the problem of ocean acidification.
 * Certainly though, while SS is correct in stable natural cycles being generally CO2 neutral, there is a net sequestration of carbon to the ocean floor, mostly I believe from diatoms. I'm not sure exactly how large that flux is though. Franamax (talk) 20:15, 17 April 2009 (UTC)

Solar Energy
How long will it take for solar heat and light to reach Earth?117.204.96.71 (talk) 16:55, 16 April 2009 (UTC) 8sec or 8 mnts?


 * The earth-sun distance is roughly 150,000 million m; the speed of light is about 300 million m/s. Divide the two and you get about 500 seconds. DJ Clayworth (talk) 17:20, 16 April 2009 (UTC)


 * Yes, that's the time it takes solar heat and light to travel the last 150,000 Gm from the photosphere to the Earth.
 * However, the sun article mentions that the "photon travel time" for the first 500 Mm from the core where gamma ray photons are produced until that energy exits the photosphere (mostly as visible light photons) is estimated as between 10,000 and 170,000 years. --68.0.124.33 (talk) 04:33, 20 April 2009 (UTC)

Lyme disease contraction vs. reporting location
CDC doesn't keep records for location of contraction of Lyme disease, only location of diagnosis. Is there any research between the correlation of the two? With the incubation period averaging 10 days, do many people contract the illness (for example, while hiking on vacation) and then travel a significant distance before being diagnosed? Or do most people contract it at or around home? 71.62.175.234 (talk) 18:12, 16 April 2009 (UTC)


 * Well, firstly, Lymes disease isn't tough to diagnose - so I would imagine most people are going to their doctors or some very local hospital emergency room to get their diagnoses - so there probably isn't much error in using the location of diagnosis.  Secondly - how would the victim KNOW where (or when) they contracted it?  The incubation period is anything from days to YEARS!  How the heck would the average patient be able to know which of all the places they visited in the last six months was the one where they were infected?


 * So, I think this explains why the CDC do what they do - and I very much doubt you'll get anything better than that. SteveBaker (talk) 20:25, 16 April 2009 (UTC)

Trip to Mars
What type of digital resources could I bring for entertainment on a fictional flight to Mars? —Preceding unsigned comment added by 167.102.160.13 (talk) 18:18, 16 April 2009 (UTC)


 * Video games? Movies? eBooks? If you weren't worried about copyright, you could pack a large variety of all of those into a rather small, lightweight package. (A solid state hard-drive, for example.) You could also bring an iPod, of course. APL (talk) 18:31, 16 April 2009 (UTC)


 * If the flight is fictional, you can bring whatever you want. That's how fiction works. Dauto (talk) 18:33, 16 April 2009 (UTC)


 * If you're headed to Mars, I'm not sure you need to worry much about the copyright-holders coming after you:) Are Martians even party to the Berne Convention? Though the MPAM/RIAM might have a thing or two to say about it... DMacks (talk) 19:45, 16 April 2009 (UTC)


 * I would expect the game to be laggy if you wanted to play video games online. 65.121.141.34 (talk) 18:46, 16 April 2009 (UTC)


 * Teledildonics? Edison (talk) 18:51, 16 April 2009 (UTC)
 * Tourist or first class? Clarityfiend (talk) 18:52, 16 April 2009 (UTC)


 * You could make yourself dream that you were a cop in 2008 but sent back to 1973. But only if you wanted a really lame ending. DJ Clayworth (talk) 19:08, 16 April 2009 (UTC)
 * Did both series have the same lame ending? —Tamfang (talk) 04:01, 22 April 2009 (UTC)

How digitally savvy are the Martians whom you plan to entertain? Cuddlyable3 (talk) 18:58, 16 April 2009 (UTC)


 * Even with todays' technology, it would be quite possible to bring along a snapshot of the entire Internet and every piece of music and every episode of every recent TV show and every movie made in English over (say) the last 20 years...let's toss in every digital book and every videogame ever written too. But even if not - those things could be downloaded via telemetry as-needed - so long as you were prepared to order movies and as you would from a subscription DVD service like NetFlicks.   So there is really no need to fill the ship with hard drives just to do that.  As '65 says - playing online games with anyone other than your crewmates would be impossible even after just a day or two of travel...the latency would make that impossible...and I think that probably rules out the otherwise excellent teledildonics idea from Edison too.  The speed of light is a harsh mistress.†  Personally, I think the thing the crew would get most benefit from would be access to email and Internet forums.  Using those kinds of inherently non-realtime service - you can have close friendships with people even when you are halfway across the Solar System...and I think the biggest stressor for such long duration flights would be having to see the same half dozen faces day after day.  But finding things to do that DON'T involve staring at a screen is by far the hardest problem.  SteveBaker (talk) 20:19, 16 April 2009 (UTC)
 * † Not as harsh as one that takes so many minutes to respond! DMacks (talk) 20:43, 16 April 2009 (UTC)
 * Apropos a mistress, don't you like analog resources even a little bit? Cuddlyable3 (talk) 21:59, 16 April 2009 (UTC)


 * You could do e-mail chess. Not much difficulty with the lag then.  65.121.141.34 (talk) 18:18, 17 April 2009 (UTC)

We are in a 6000 degree C space cloud?
That's according to. Then why aren't we burning up?128.163.236.55 (talk) 18:40, 16 April 2009 (UTC)


 * The same article says the cloud density is only 0.26 atom per cc. Cuddlyable3 (talk) 18:50, 16 April 2009 (UTC)


 * Last phrase from the article you linked: "The Local Interstellar Cloud's potential effects on Earth are prevented by the solar wind and the Sun's magnetic field". The cloud is too thin. It pays to read an article all the way to the end. Dauto (talk) 18:53, 16 April 2009 (UTC)


 * Temperature is almost meaningless in such a near-vacuum situation. At reasonable gas densities it's a measure of how fast the molecules are rushing around.  But when there are hardly any molecules there, the distinction between a large body of very thin gas that's merely travelling along and an actual hot gas, becomes almost non-existant.  What you have to consider is the amount of energy contained in that gas - that's a function of it's density and it's temperature - but because it's practically a vaccuum - it's density is all but negligable - so it's not able to transfer significant energy into nearby planets and such.   If it did transfer energy into the earth - then the parts of the cloud nearest us would instantly cool down to the same temperature as the earth and because thermal conductivity of such a thin gas is terrible - it would take millennia for any significant amount of additional heat to make it through to us.   So the total energy transferred from the cloud to us is far FAR too small to measure. SteveBaker (talk) 20:06, 16 April 2009 (UTC)


 * The temperature of the cloud is shown by the shape of the spectrum of its thermal radiation, not the tiny thermal power that reaches us. Cuddlyable3 (talk) 21:54, 16 April 2009 (UTC)


 * Temperature is a measure of the average kinetic energy of the molecules of a substance. Basically, its the speed at which those molecules move.  One substance can transfer thermal energy to another substance only when molecules of that substance bump into other molecules and make them go faster.  So, there are two important things here: the speed the molecules are moving, AND how often those molecules bump into you.  A substance which is so diffuse that a molecule only hits you like every few seconds will not efficiently transfer much energy to you.  A single molecule striking you at a temperature of 6000 degrees has such a tiny effect on heating you up that you wouldn't even notice.
 * So, even though those molecules are whizzing around at a super fast speed, there are not enough of them around to effectively raise your temperature much at all. In fact, if you were in this environment, uninsulated, you would radiate heat energy much faster than it could be replaced by the occasional 6000 degree molecule bumping into you.  You wouldn't burn up, you'd freeze to death, not because the temperature of the surrounding molecules isn't higher than your base temperature, but because there just aren't enough of them around to keep you warm, regardless of how fast each molecule is moving.  --Jayron32. talk . contribs  01:16, 17 April 2009 (UTC)

What is the name of the quantity that is represented by the energy function of density and temperature? (What Stevebaker mentioned)199.76.189.187 (talk) 23:13, 17 April 2009 (UTC)
 * Well, I think that density X temperature (X volume) gives you the total thermal energy of the system, which is a quantity. Density X temperature per unit volume would be specific energy, since volume is not an absolute term (it depends on the relative scale you measure it with, unlike density and temperature which are absolute scales). Or possibly energy density, unlike several others here I'm not an expert!
 * But you asked why we're not burning up - that's not a quantity, it's a function, namely the heat transfer function. In this case, there are so few of those really hot molecules hitting us to make a difference. We absorb and emit far more energy through other processes, it's there, but it doesn't make us burn up. Generally, I think Jayron said it best. Franamax (talk) 00:34, 19 April 2009 (UTC)

Ecology book, online source?
My girlfriend is trying to refrence a refrence from an article, and her instructor won't let her use it. I was wondering if anyone could help me find an online or downloadable copy, preferably a PDF, of the journal. The journal is "Perspectives in Plant Ecology, Evolution and Systematics," the author she's referancing is S.J. Wright. Though, this may present a problem, in that, the author, of the journal, may be referencing another author, I just don't know.

I, personally, don't see how it's logical to disavow a referance of a reference; That's all that research articles and science books are nowadays, right? —Preceding unsigned comment added by HitmanNumber86 (talk • contribs) 22:20, 16 April 2009 (UTC)


 * Would the title of the article be The myriad consequences of hunting for vertebrates and plants in tropical forests? That's the only article I can see by SJ Wright in that journal. It looks like you can only get the full article by buying a downaloable copy, which costs $31.50. If your girlfriend is attending a college or similar institution, she may be able to access it for free, if they have a subscription. The college librarian(s) should be able to point her in the right direction.-- Kateshort forbob  22:38, 16 April 2009 (UTC)


 * Google Scholar is great for stuff like this, because often you can find downloadable versions of things that aren't easily available from the journal web site. This is such a case:  here is a pdf version. Looie496 (talk) 23:45, 16 April 2009 (UTC)
 * When I studied for my last degree, this sort of thing was counted as academic misconduct: quoting a reference that was not consulted. The idea was to note down the actual document used, not necessarily where that author got their original idea from.  Then you are covered if there is misinterpretation or alteration of the original author's writings. And you are not claiming to have read all those references you did not see. Graeme Bartlett (talk) 22:20, 17 April 2009 (UTC)
 * Yes, but reviewers often complain if the original source of an idea is not cited -- especially if the reviewer is the original source. I believe it is pretty common to cite papers that have only a peripheral importance based on a general understanding of their findings rather than a close reading.  It's a writer's responsibility to cite papers correctly, but this is not something that people frequently obsess over. Looie496 (talk) 16:41, 19 April 2009 (UTC)
 * If it really isn't practical to check the original source, the appropriate course is to cite it as "$ORIGINAL, as summarised/translated/represented/etc in $THINGIACTUALLYREAD". This satisfies both honesty and attribution. IME, second-hand citations are horribly unreliable; they should be avoided when possible and otherwise flagged. --GenericBob (talk) 05:26, 20 April 2009 (UTC)

Reaction product
When I react ascorbic acid and sodium bicarbonate, it yields sodium ascorbate, water, and what? Thanks, Reywas92 Talk  23:18, 16 April 2009 (UTC)


 * Is this a homework question?  Wisdom89  ( T |undefined /  C ) 23:23, 16 April 2009 (UTC)
 * Just help me, dangit. I've got C6H806 + NaHCO3 -> H2O + the formula for sodium ascorbate + unknown. I'm thinking carbon dioxide, but I'm not sure. Reywas92 Talk  23:32, 16 April 2009 (UTC)
 * If it's homework, then making you do it yourself is helping you. We can give you help if you're stuck on specific concepts, but we can't just give you the answer. Why are you assuming a 1:1 ratio for the reactants? What atoms do you have left over? Franamax (talk) 00:01, 17 April 2009 (UTC)


 * Do the metathesis (or double replacement reaction) just as you would expect to, and you will get two products. Just swap the positive ions between the two compounds, and write the new formulas, balanced for charge of course, and show what you EXPECT to get.
 * Read this article or, look at the formulas of the two compounds you got doing this the standard way, and compare to what your homework problem SAYS you can get. It will require you to do a little subtraction problem.
 * If you do these things, you will get the correct answer. If you just berate people who are trying to help you figure out the right answer, you won't get much more help from us... --Jayron32. talk . contribs  01:07, 17 April 2009 (UTC)

Black Desert
I would like to find/receive information regarding the Black desert in Egypt.--Infonews101 (talk) 23:59, 16 April 2009 (UTC)
 * Searching Google for "black desert egypt" turns up quite a few links. Shockingly, we seem to have no article on the Black Desert, though we do have one on the White Desert just next door. Franamax (talk) 00:13, 17 April 2009 (UTC)
 * Libyan Desert might also have been useful, but fails to mention it. 76.97.245.5 (talk) 10:49, 20 April 2009 (UTC)