Wikipedia:Reference desk/Archives/Science/2008 October 24

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October 24

Contrail, crepuscular ray, zodiacal light, or other?

Hi. At around 6:30 pm EDT today, I saw a glow in the East West. The sky was orange near the horizon, but below the orange was a layer of cloud stretching horizontally across the horizon. The pillar/tail-like glow was more reddish and brighter than the surrounding sky, and I estimate it stretched about 35 degrees tall and 10 degrees wide. By the time I got home, I couldn't take a picture because it had dissapeared. At the time I saw the glow, the sky was too light for me to find either Venus or Jupiter. Could it have been a contrail? I've seen contrails spreading to 10 degrees wide, but today I saw a contrail persist, but I don't think it was humid enough today to allow contrails to spread that far, although an earlier contrail appeared reddish in colour (location: S. Ontario). I think it might have been a crepuscular ray, but do those occur after sunset? Or, could it have been another type of sky glow associated with the sun? I know it wasn't illuminated by anything other than the sun, because it was really close to where the sun had set and higher up it was dimmer. I might have also seen other lower glow patches similar to this one apparently eminating from behind the cloud, perhaps suggestive of a crepuscular ray, but those were less distinct if they existed. What about the zodiacal lights? Very few streetlights had turned on near where I was observing this from by the time I first saw it. However, don't they usually spread up to 60 degrees from the horizon, appear as a triangle, and occur later after sunset? In SkyNews magazine, they mentioned an opportunity to see the zodiacal lights, but that was for late September and in the early morning. So, any ideas? Could it have been something else? Thanks. ~AH1^(TCU) 01:21, 24 October 2008 (UTC)

Do you mean in the West? In the East after sunset wouldn't be close to where the sun had just set... --Tango (talk) 11:45, 24 October 2008 (UTC)

Oops, yes I did mean in the West. ~AH1^(TCU) 13:05, 24 October 2008 (UTC)

Earths atoms

How many atoms are in the Earth? Is it even possible to calculate this, and if so, how many pages of numbers would you need to display the amount? 63.245.144.77 (talk) 02:14, 24 October 2008 (UTC)

Don't know if this is homework or not, but I'll assume good faith. Google show several answers for number of atoms earth: [1], [2], [3]. They roughly agree on the number, ~10^50. And as you can see, thanks to the benefit of scientific notation, the answer is very short. Even if you were to write out every digit, it would still easily fit on one page (1 followed by 50 zeroes). - Akamad (talk) 02:27, 24 October 2008 (UTC)

130 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 atoms, give or take. Dragons flight (talk) 02:33, 24 October 2008 (UTC)

Can I get a recount? :) 67.184.14.87 (talk) 16:01, 25 October 2008 (UTC)

Well - the others have given you the correct answer - but you should really know why it's actually VERY easy to calculate this number - so I'm going to show you which Wikipedia pages I went to and how I did the math.

If you made the assumption that it was very roughly 1/3rd iron, 1/3rd oxygen and the other third was about as dense as silicon - (you can look it up in Abundance_of_elements_on_Earth) then you could look at the mass of the earth 6×10²⁴kg (from our article Earth)- which is 6 followed by 24 zeroes - and say that there was roughly 2x10²⁴kg of each of those three elements. The Avogadro constant says that there are 6×10²³ atoms in every "mole" of a substance. A mole is defined as the atomic weight of the atom times one gram - and we can go to the articles on Iron, Oxygen and Silicon to find out their atomic weights. So there are 6x10²³ atoms in every 16 grams of oxygen, in every 56 grams of iron and in every 28 grams of silicon. There are 1000 grams in every kilogram - we have to divide the mass of each of the elements in the earth (roughly 2x10²⁴kg - or 2x10²⁷grams) by the number of grams we just figured out - and that gets us to get the number of moles of each substance in the entire earth - then we can add those up and multiply by Avogadro's constant to get the number of atoms. So we get out our 12" slide-rules (you can use a calculator) and figure:

( 2x10²⁷ / 16 + 2x10²⁷ / 56 + 2x10²⁷ / 28 ) x 6x10²³ = 1.3 x 10⁵⁰

...which is 13 followed by 49 zeroes - which is (suspiciously) identical to the number that Dragons flight just gave us...suggesting we both made the exact same decisions when it came to approximations (or SOMEONE was looking over my shoulder). Anyway - with the limited information we have about the precise composition of the earth's core - this is a fairly rough estimate - it couldn't be twice that number - or half that number - but we could easily be 25% off if the geologists are wrong about the amount of nickel in the core or something like that.

Oddly - we could tell you the total number of protons and neutrons in the entire earth - that's MUCH easier and we know the answer to surprisingly good precision! It's just Avogadro's constant times the mass of the earth in grams - and that comes out to about 3.60x10⁵¹. That's actually a fairly accurate number because it doesn't depend much on what the earth is made of - only on how heavy it is and what Avogadro's constant is - both of which we know to better than a tenth of a percent.

SteveBaker (talk) 04:56, 24 October 2008 (UTC)

I posted two hours before you. I can only conclude that you are spying on me. AAAHHHH!! Dragons flight (talk) 11:25, 25 October 2008 (UTC)

Thanks, guys! and this was not homework, by the way, I was just curious. While we're on the subject, how many atoms are in the entire solar system? :D

And how did they calculate the earths weight anyway? I would imagine it has something to do with it's motion or something, but there I go pretending to understand anything Newton said. :P 63.245.144.77 (talk) 07:14, 24 October 2008 (UTC)

Wheighing the Earth was traditionally done with the Cavendish experiment. This doesn't actually weigh the earth, but the gravitational constant. If we know this constant, then using the shell theorem for simplification, we only need to measure the acceleration of gravity and the Earth's radius to weigh it accurately. Someguy1221 (talk) 07:21, 24 October 2008 (UTC)

Entire solar system is easy. From our article on the Sun, we find that the Sun represents about 99.8% of the total mass of the solar system. For practical purposes, we can safely ignore all the other planets, asteroids, dust, comets, and what have you. The Sun's mass is about 2x10³⁰ kg, its composition is about 25% helium and 75% hydrogen. (There are traces of other elements totalling about 1% of the Sun's mass; again, we can safely ignore those for an atom count.) The actual math is left as an exercise for the reader. TenOfAllTrades(talk) 13:17, 24 October 2008 (UTC)

Yep - so it's the same calculation as for the Earth - but with different numbers: 5x10³²g of helium (atomic weight 4) and 1.5x10³³g of hydrogen (atomic weight 1) - so 3.5x10³³ moles which is 1.2x10⁵⁷ or 1,200,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 atoms in the sun (or the entire solar system...it's about the same number). Since I just KNOW you're itching to ask...for the entire milky-way galaxy - it's about 6x10¹¹ times the mass of the sun - and has about the same composition (except for dark matter, black holes, neutron stars and other things that maybe don't have atoms per-se) - so we'll go with 7x10⁶⁸ for the entire galaxy. For the entire universe we don't know - it's probably infinite. But for the "observable universe" - which is all we can ever see or interact with - every single atom that "matters" to us - it's about 10⁸⁰ atoms:

100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

Since that's mostly hydrogen - the number of protons and neutrons is about the same - if you add in the electrons you can roughly double that number. Toss in the photons, and count quarks and maybe you get to add one more zero...but it's still not enough to fill even one line of text on my monitor - let alone an entire page! Heck it's not even close to a Googol.

For really big numbers, the number of possible games of chess is estimated to be 10¹²⁰ - which might just take two lines of zeroes if you use a nice big font size.

For afficianado's of really REALLY big numbers, it's hard to top Graham's number (which genuinely comes up in real mathematics in Ramsey theory). It is truly, unimaginably large - you'd need more zeroes (by far) than there are hydrogen atoms in the visible universe to write it down...even in 10^N notation - there would be more digits in N than there are atoms to write it down with. Mathematicians have invented an entirely new notational system just to express this number in any reasonably compact form!

I hope Graham's number doesn't disappoint as much as atom-counting does! SteveBaker (talk) 13:55, 24 October 2008 (UTC)

Apparently, there are "specific integers known to be far larger than Graham's number", but it's hard/impossible to comprehend what "far larger" means in relation to something that's already incomprehensibly large. -- JackofOz (talk) 23:11, 24 October 2008 (UTC)

Conway chained arrow notation can easily produce numbers which are far larger than Graham's number and express them in a very compact form. I was led to believe that Graham's number's claim to fame is that it is the largest number that has appeared in a published mathematical paper. SpinningSpark 23:33, 24 October 2008 (UTC)

"Build a better mousetrap, and someone will build a better mouse"

Are there any confirmed cases of increased trap resistance in mice (in general, or at a particular site) following a particular advancement in the mousetrap (in general or at the site), comparable to antibiotic resistance in bacteria?

On a related note, might building better mice be a more promising line of endeavour than building better humans, if undertaken for the same ultimate purposes? If so, might building better mousetraps be a more cost-effective way to do it than more direct human intervention? NeonMerlin 06:24, 24 October 2008 (UTC)

It really seems unlikely that they'd become resistant to mechanical traps. That would really require some kind of genetic change that made them avoid traps specifically - but not become so timid and nervous as to be unable to function in the world. So few mice out of a typical population are caught by traps that the probability of such a very specific evolutionary change being statistically beneficial is rather low. On the other hand, it's known that some vermin have become resistant to poisons we put out for them. Rats (and perhaps mice) that have evolved a resistance to warfarin (a common rat poison) certainly do exist. In that sense, someone built a better mouse poison - and nature produced the 'better' mouse. We now have still better poisons - and it's only a matter of time until still better mice appear. So the old saying isn't so far from the truth. SteveBaker (talk) 13:26, 24 October 2008 (UTC)

Indeed, resistance to mouse traps would require a way to tell the difference between food and bait, which is very hard seeing as they are usually the same thing! I could see mice evolving a fear of plastic, or something, so avoiding plastic traps (I'm not sure what most traps are made of these days) but that's about it. --Tango (talk) 17:37, 24 October 2008 (UTC)

I read somewhere that Australian natives had thicker skulls probably because of fights where they hit each other over the head. And I've wondered what adaptations will occur in Americans because of the large number of young people killed by guns and cars. If mechanical traps kill more than about 1 in a thousand then it's pretty certain evolution will change them in a way to compensate somewhat if at all possible. So yes we're probably eventually going to have either smarter or more hardy mice. Dmcq (talk) 14:38, 24 October 2008 (UTC)

The snap-traps (I assume we're talking about those) are a valid envionmental factor, might be noticeable if the population were isolated. In my West Philly apartment years ago, I wound up placing both snap-traps and glue-boards in the same places since after a while of using "just one type", I stopped catching them reliably. Lighter? Faster? Able to smell something about the glue? Ultra-short tails? Sacrifical/regenerative feet? Who knows when kind of Frankenmouse I would have been able to evolve if I hadn't moved. OTOH, given um, "the scale of the experimental population I appeared to have", I was happier not hanging around to see the results. DMacks (talk)

I used to live in a mouse infested house and I too can confirm that after an initial period of catching lots of them, the rate then falls off with no discernable reduction of the mouse population. Pure opinion, but I believe the answer is quite simple: the surviving mice can see the dead or injured one in the trap and they then learn that traps are dangerous. Changing the bait, position or type of trap will often succeed in catching out another batch. SpinningSpark 23:51, 24 October 2008 (UTC)

Did you wash the traps? I'd be willing to bet that mice can smell where another mouse died a nasty death. My experience with mice is to first of all eliminate the food sources that may have brought them around, then put out some tasty, tasty bait and the snap-traps work 100% over the course of 3-4 weeks. Finding and cutting off the food source is the big one, cleaning the death-smell off the trap is next, then move the traps around and change the bait. Mice rely on rapid reproduction as an evolutionary strategy, there's no particular genetic pressure to evolve mechanism-awareness. Franamax (talk) 11:16, 25 October 2008 (UTC)

We're in a pickle if people do that to cope with gun crime and cars. Dmcq (talk) 12:14, 25 October 2008 (UTC)

Do any animals shed tears through grief or pain?

I’ve wondered about this since I saw the documentary movie “The Weeping Camel”, which deals with a nomadic Mongolian family. This family’s camel gives birth to an albino calf, which she rejects. Following an ancient tradition, the family recruit a musician from a nearby town who plays the violin to the camel, whose attitude softens, and with tears flowing freely from her eyes, takes the infant to her teat. These scenes are not recreations, but actual footage of real events.

When I was little, my mother told me that on her family’s farm she saw cows weep when separated from their calves. And I myself have seen an ancient Egyptian engraving of a man milking a cow. The cow’s calf has been tied up nearby so it cannot access its mother’s udder, and the cow is depicted weeping profusely. Is this just anthropomorphism, or are animals capable of weeping through sadness or pain. Of course, I imagine that all animals can shed tears if they get grit or onion vapour or suchlike in their eyes, but that is not the kind of weeping I mean. Has anyone seen or heard anything which can throw light on this? Myles325a (talk) 06:37, 24 October 2008 (UTC)

I don't recall specific examples, but the book When Elephants Weep did provide (admittedly rare) examples of animals crying from grief. 152.16.59.190 (talk) 10:42, 24 October 2008 (UTC)

Observers of a band of gorillas reported that when the mate of a retired leader was killed by a young band of tough guy gorillas, the old guy cried. Edison (talk) 15:14, 24 October 2008 (UTC)

:( --98.217.8.46 (talk) 15:18, 24 October 2008 (UTC)

My dog Harry, a Border Collie, wept once.130.86.14.12 (talk) 04:07, 27 October 2008 (UTC)

oil and butter

why butter gets solidify but oil does not in refigerator. —Preceding unsigned comment added by 117.99.20.15 (talk) 09:18, 24 October 2008 (UTC)

I'm going to guess something to do with fat is the reason. 194.221.133.226 (talk) 09:20, 24 October 2008 (UTC)

butter: long straight saturated fatty acid chains => good fitting into crystal => high melting point

oil: long bend unsaturated fatty acid chains => not so good fitting into crystal => low melting point--Stone (talk) 12:53, 24 October 2008 (UTC)

nicotine

how long does nicotine remain in the blood after a person ceases smoking —Preceding unsigned comment added by 121.222.177.13 (talk) 11:29, 24 October 2008 (UTC)

Nicotine says it has a half-life of 2 hours in the body. So after 2 hours, there is half as much, after 4 hours a quarter as much - and so on. In practical terms, it's essentially gone in less than a day. SteveBaker (talk) 13:20, 24 October 2008 (UTC)

Is that why I need a cig at least every 2 hours?--GreenSpigot (talk) 19:46, 26 October 2008 (UTC)

It's why you think you need one. ;) - Mgm|^(talk) 08:18, 27 October 2008 (UTC)

Common cold and temperature

Or flu. In any case, I've heard a "common sense" wisdom that getting frozen outside in cold wheather, or even eating something cold when you are sweating, increases the chance of getting infected. I could never find a scientific explanation for that; is it just a folktale or is there some science behind it? --_{Piotr Konieczny aka Prokonsul Piotrus| talk} 13:35, 24 October 2008 (UTC)

Add to that, getting your hair wet in a rain. :) Zithan (talk) 14:42, 24 October 2008 (UTC)

Nope - no truth to it at all. SteveBaker (talk) 15:20, 24 October 2008 (UTC)

Other than the fact that when it is colder out, you stay inside with others more than when it is warmer out, thus increasing your chances of standing next to a disease vector. --98.217.8.46 (talk) 15:37, 24 October 2008 (UTC)

But then, when your mom says "you can't go outside because you'll catch a cold" - so you stay inside more - then (if your theory is correct) you'll be far more prone to colds than if you went outside to play. SteveBaker (talk) 18:49, 24 October 2008 (UTC)

When in doubt, do the exact opposite of everything your parents tell you. Seems like a good rule to me! :) --Tango (talk) 19:42, 24 October 2008 (UTC)

Colds or flu are viruses that don't survive well outside of the nice, wet, warm environment of a human being. There are a number of theories of why they exist more often during the winter months, but it could be everything including lower levels of UV radiation during the winter which eradicates airborne viruses, dryer air in winter which causes respiratory passages to be more sensitive to infection, closer proximity to other virus carrying individuals, or poorer nutrition. It's probably a combination of that and much more. OrangeMarlin ^{Talk• Contributions} 17:01, 24 October 2008 (UTC)

The "rule" I was taught was that it's ok to have a window open to let in some fresh air, even in cold weather, if you like a cold breeze. But if you have 2 windows open, then you'll create a draught, and draughts cause colds, flu, pneumonia and even death. This always seemed utterly absurd to me. Is there any truth to it, whatsoever? -- JackofOz (talk) 23:02, 24 October 2008 (UTC)

I'm pretty sure this question has been asked many times before. Although the cold temperature itself will not give you a cold, I've seen a lot of studies implying that when it's cold, your body heat is more restricted, and since body heat helps blood flow, and blood has white blood cells in it, the cold may slow down the immune system, and if viruses are present, then your body is more likely to catch a cold than otherwise. I've found that especially in a close public envorironment, such as a school, the first flu outbreak often seems to coincide with the first rapid cooldown in temperature (I live in Canada). Of course the cold temperature itself cannot give you an actual cold or flu, it may help start one if viruses are present, because "viruses can live on surfaces for days" (source: Lysol commercial). I remember a while back that one time I was outside for about two hours at night with the wind blowing at 40 km/h and the temperature about -10C. The next day, I had a fever of 40C, I barely went outside for a week, and lingering symptoms may have lasted a month (although it was different from a severe common cold where your body would ache all over). Although I probably already had a cold/cough by the time I went outside, the going outside in the cold seemed to make it worse each time. Also, it has been said that being in cold, wet clothes or by walking on cold surfaces barefoot can cause joint pain. I'm not sure if this is true, but one time after being wet I had back muscle pain and a minor cold (but there was already a cold going around). So the point is, and again I'm not an expert on this, that although cold temperatures won't give you a cold, the viruses might. Also, it seems that what always happens is that until something has solid proof, it is considered nonexistant. ~AH1^(TCU) 23:18, 24 October 2008 (UTC)

(Also, we cannot give medical advice) ~AH1^(TCU) 23:20, 24 October 2008 (UTC)

I can't see how the number of windows open is going to be what's important, it will be the actual temperature. Having two windows open causes air to flow in one and out the other and more effectively ventilate the room which will make it colder, however I can't see the difference between that and having one window open on a day when it's just colder outside to start with. There might be a difference to the humidity with a through breeze rather than just one window (it will be lower in a well ventilated room, I would think) which may make a difference, I suppose. --Tango (talk) 00:42, 25 October 2008 (UTC)

Thanks, that's what I've always believed too. But I couldn't tell you how often I was told to be more wary of "draughts" than of simple "breezes". Some old wives tales die harder than others, apparently. (Not saying my mother was an old wife .... well, she is these days, I guess. ) -- JackofOz (talk) 01:38, 25 October 2008 (UTC)

See also Common cold#Exposure to cold weather. PrimeHunter (talk) 01:56, 25 October 2008 (UTC)

http://www.newscientist.com/article/dn12808-cold-weather-really-does-spread-flu.html --Digrpat (talk) 02:15, 26 October 2008 (UTC)

Jury still out? [4]--GreenSpigot (talk) 20:14, 26 October 2008 (UTC)

See Lowen AC, Mubareka S, Steel J, Palese P (October 2007). "Influenza virus transmission is dependent on relative humidity and temperature". PLOS Pathogens. 3 (10): 1470–6. doi:10.1371/journal.ppat.0030151. PMC 2034399. PMID 17953482. --Arcadian (talk) 22:23, 26 October 2008 (UTC)

Dehumidifier crystals

Anyone know what the dehumidifying chemical in car antifreeze is called? I want to get some in crystal form to use as a cheap room dehumidifier. Last week I read on a forum that it will soak up water from the air without any fans or pumps, if I just spread it out in a large tray on the floor. It can be dried out over a barbeque and reused many times. But I lost the link and can't remember what the chemical is called.

If this stuff is actually poisonous then please let me know before I use it...!! Thanks! — FIRE!^{in a crowded theatre...} 14:06, 24 October 2008 (UTC)

Dehumidifiers in antifreeze? That's silly. You mix the stuff with water in your car and it's sold as a 50/50 mixture of the actual chemicals and water! According to our article antifreeze contains ethylene glycol (the actual stuff that messes with the freezing point of the water) - which is horrifyingly toxic but smells and tastes really sweet so that animals and children are attracted to it, some pretty colored dyes (to make it look like gatorade as well as taste like it?!?!)...plus (sometimes) an embittering agent to make it taste terrible (guess why?!) and some stuff to prevent corrosion in your engine. No 'dehumidifiers' there! You are probably thinking of those little pouches of Desiccant crystals that come with some electronic equipment to keep them dry during shipping. Our article offers some possible dessicants you could try. Rice is an interesting choice! SteveBaker (talk) 14:32, 24 October 2008 (UTC)

Here's an interesting fact. If somone drinks ethylene glycol and are unable to get to a hospital, give them ethanol and it acts as the antidote. They'll be drunk AND safer than before, just don't top them with loads of vodka. —Cyclonenim (talk · contribs · email) 17:12, 24 October 2008 (UTC)

• Sounds like silica gel to me. --jpgordon^∇∆∇∆ 15:22, 24 October 2008 (UTC)

• • If you want to try silica gel, your local pet supply store may carry jugs of silica gel, intended for use in a cat litter box. Since my cat is content with clay litter, I did not try the silica gel and I can't say if it is better than using clay. But you may find a pet supply an economical place to buy silica gel. Wanderer57 (talk) 15:41, 24

October 2008 (UTC)

Thanks!! It was calcium chloride. Hope it actually works though. You're right (now I stopped to think) that dessicants in antifreeze would be a really stupid idea... :-) It does seem to be used in window deicers though, or is that another red herring? — FIRE!^{in a crowded theatre...} 18:58, 25 October 2008 (UTC)

Hardware stores sell "dehumidifiers" consisting of calcium chloride crystal in a container. They absorb a modest amount of moisture from the air gradually, not as fast as a typical dehumidifier. Edison (talk) 00:38, 26 October 2008 (UTC)

Freak Of Nature?

Okay i got a hampster like 4 weeks ago its grown ALOT since then Well let me explain what happned i sorta left the lid off his container and he got out i lost him for like 3 days then in the living room i see like a dog sized hapster on the floor alive but the carpet was all ripped up any idea what happned? (this is a serious question i want a serious answer) mostly what happned to the carpet...—Preceding unsigned comment added by Nikkicole08 (talk • contribs) 16:17, 24 October 2008 (UTC)

Well, they do have little claws and like to make burrows. My question is, can we have a picture of your gigantic hamster? o.o --Masamage ♫ 16:39, 24 October 2008 (UTC)

Is the hamster actually gigantic or does it just have its pouches stuffed with carpet? Hamsters like to collect nesting material and will sometimes fill their pouches (in their cheeks) with so much of it that they look ridiculous! --Tango (talk) 16:41, 24 October 2008 (UTC)

Dog sized hamster? What breed of dog? I am afraid the most likely explanation is that a hamster-like dog (Griffon Bruxellois perhaps?) has broken into your house and eaten your hamster. It is likely that your dog-hamster is also responsible for eating the carpet. SpinningSpark 22:58, 24 October 2008 (UTC)

By any chance are we talking about a miniature giant space hamster? Plasticup ^T/C 00:34, 25 October 2008 (UTC)

Writing after laughing hard

I often find I have enormous difficulty writing after I have had a good hard laugh. My hands feel like rubber, and I cant hold the pencil much less touch the tip to the paper. I was wondering what happens in the nervous system while this is going on. —Preceding unsigned comment added by 189.58.26.29 (talk) 16:24, 24 October 2008 (UTC)

It sounds like a mild form of cataplexy. Axl ¤ [Talk] 17:55, 24 October 2008 (UTC)

Of course we NEVER give medical advice or make diagnoses based on vague symptoms. Edison (talk) 20:57, 24 October 2008 (UTC)

Laughing causes your muscles to relax. If you try holding something heavy and laugh at the same time, you'll likely drop what you're holding. This is not a medical condition; It's a natural response.CalamusFortis 02:43, 25 October 2008 (UTC)

Laughing very hard for a long time can often make you short of breath, and almost always increases your heart rate. The weakness in your hands could well be due to the release of chemicals such as epinephrine —Cyclonenim (talk · contribs · email) 09:15, 25 October 2008 (UTC)

Satellite dish cable

I shall be grateful to learn what currect passes through the cable from the decoder to the dish. Can it be cut without insulated cutters ?90.0.133.146 (talk) 16:46, 24 October 2008 (UTC)DT

How difficult would it be to unplug it? It's always best to err on the side of caution when dealing with electricity. I wouldn't trust random people on the internet with my life! --Tango (talk) 16:57, 24 October 2008 (UTC)

If you have to cut it, unplug it first or buy insulated cutters. —Cyclonenim (talk · contribs · email) 17:10, 24 October 2008 (UTC)

Preferably both. --Tango (talk) 17:33, 24 October 2008 (UTC)

There is probably not a good answer to this as it probably depends a lot on the type and brand of dish. APL (talk) 18:18, 24 October 2008 (UTC)

Usually, there is some electronics in the dish itself - that must require power from the decoder. The video stream coming from the dish to the decoder is going down the same cable - so it must be a co-axial cable. Cutting that will almost certainly not harm you because the voltage isn't gonna be huge - but cutting co-ax almost always puts a short across the end of the cable. If it's still plugged into the decoder and the decoder is powered up - that could easily short out it's power output to the dish - and that could damage the decoder. Hence you should certainly unplug the decoder from the wall when you do this - and REALLY it would be best to disconnect the wire at the back of the decoder before cutting anything. SteveBaker (talk) 19:46, 24 October 2008 (UTC)

The voltage could be around 12 volts, and perhaps a quarter to half an amp. The decoder gear I have seen can detect a short, so it would not be damaged, but if you get the oportunity disconnect. The voltage is probably not dangerous to you as a cutter. In some systems the voltage can be changed to signal the LNB to change bands or polarization. Graeme Bartlett (talk) 20:45, 24 October 2008 (UTC)

Thank you.86.219.39.92 (talk) 15:52, 25 October 2008 (UTC)DT

Staining in chilly weather

Some paint cans have warnings on them not to use below 45 or 50 degrees F. What happens if you paint or stain below that temperature? Will it just be slower to dry, or will it fail to dry correctly? I apologize for such a boring question. It's almost as boring as, well... damnit. Fletcher (talk) 19:45, 24 October 2008 (UTC)

I don't know the precise mechanism - but I know that when I painted some wood at around 35 degF, it didn't turn out well. It was almost as if the oil and the pigment wouldn't stay mixed and there was this oily residue on top of the finished surface. It never did really dry properly and it was streaky and patchy. I ended up scraping it all off and re-doing it. The paint manufacturers have nothing to gain from lying to you about this - so you should probably believe it when they tell you. SteveBaker (talk) 19:49, 24 October 2008 (UTC)

Interesting...thanks. I'll be hoping for warmer temperatures. Fletcher (talk) 20:01, 24 October 2008 (UTC)

This explains it pretty well. --jpgordon^∇∆∇∆ 20:19, 24 October 2008 (UTC)

Seems oil has a 10° advantage over latex, which is good for me. Just hope it doesn't rain! Fletcher (talk) 20:44, 24 October 2008 (UTC)

It is more likely to adhere poorly and peel off later if applied when it is colder and/or damper than recommended. Edison (talk) 20:53, 24 October 2008 (UTC)