Wikipedia:Reference desk/Archives/Science/2008 September 10

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September 10

reason for .b1 and .g1 primer names

In sequencing of DNA, reads will sometimes have .b1 and .g1 for the forward and reverse primers when producing amplicons. Does anyone know why the letter b is associated with forward and why g is associated with reverse? Thanks. --Rajah (talk) 02:39, 10 September 2008 (UTC)

No one seems to have an answer, however this is what I have found: There are primers called A1 A2 B1 B2 C1 C2 D1 D2 E1 E2 F1 F2 G1 G2, with the 2 primer for use on the alternate strand to the 1 primer. Also different primers are indicated by the same symbols by different researcher. So your primers must be in the context of some system or commercial product - can you say which one? Graeme Bartlett (talk) 21:55, 11 September 2008 (UTC)

1st column of slide 10 of http://snp.wustl.edu/snp-research/c-briggsae/Files/EMBO-Genetic-Map-Koboldt.ppt --Rajah (talk) 18:40, 13 September 2008 (UTC)

Carbon dioxide sequestration

There is a lake somewhere inside a volcano cone that sequestered CO2 coming from the volcano at the bottom of the lake do to the temperature and pressure at the bottom. A tremor or some other disturbance released the gas and its spread over the slopes and kill people and livestock. How much risk of this is there in the man-made sequestration of CO2 in ocean bottoms and oil fields and the like? —Preceding unsigned comment added by 71.100.10.144 (talk) 04:20, 10 September 2008 (UTC)

• That was Lake Nyos, in case someone wants to read more about this. --Anonymous, 20:08 UTC, September 10, 2008.

The ocean bottom is risky, if the super carbonated water comes to the surface it will foam up in a big way. ANother risk is acidification of the water with dissolving of shells and bones of sea creatures. With underground storage, it presumably will be pumped back into a gas well that is reasonably well sealed, but as you say a rupture could release the gas again. Natural kinds of these ruptures can crack at the rate of about one kilometer per second and erupt at the surface in a special kind of explosive volcano as a Kimberlite pipe. Graeme Bartlett (talk) 05:30, 10 September 2008 (UTC)

A) The ocean already has ~50 times as much dissolved carbon as the entire atmosphere, so it is implausible that you could pump enough carbon into the ocean to really pose a threat due to gaseous discharge (i.e. Lake Nyos) B) The key word for Kimberlites was "volcano", their source needs to be at least 1000 C. You can't really compare a capped well to a deep, fast moving flow of molten rock and dissolved gas. Dragons flight (talk) 05:48, 10 September 2008 (UTC)

The issue with the ocean is putting too much in too little water. At pressures of 100 bars you can dissolve plenty of carbon dioxide. Cool carbon dioxide breaking out from a well would be dangerous to humans and animals due to suffocation. It does not need to be heated to 1000 degrees. Carbonatites can be as low as 600° degrees. By the way does anyone know how to get the degree symbol that used to be down the bottom of the edit box? Graeme Bartlett (talk) 05:56, 10 September 2008 (UTC)

My understanding of ocean storage is that the CO2 will be simply pumped into the ocean depths, rather than stored in the sub-floor as in above-ground CCS schemes. This avoids the catastrophic-release problem, but presents others such as the massive formation of carbonic acid and uncertainty on the speed of return to atmosphere.

And I'll try to make a degree symbol from the default Insert menu right now: ° Does that look right? Franamax (talk) 06:04, 10 September 2008 (UTC)

Hey thanks that ° works, my menu selection was on wiki markup! To work out the risk there may have to be a proper risk assessment looking at how many people are killed, economic loss, non productive use of energy etc. The lowest risk option may be to put the carbon dioxide in the air. There would not be enough old oil and gas wells to take all of the power station emissions of CO₂ in any case. I much prefer the real soylent green method. Another way is to reproduce the azolla event that stripped the atmosphere of carbon dioxide. Also the end of the cryogenian was a time when huge amounts of carbon dioxide were removed, but this cannot be done now. Graeme Bartlett (talk) 06:14, 10 September 2008 (UTC)

Actually, estimates suggest there are enough geologic repositories to eat all emissions for 100 years or so. Doing so would require drilling new wells, usually into deep (2+ km) saline aquifers, but that's not too big a deal. We annually remove ~3×10¹² m³ of natural gas from the Earth. We have about 20×10¹² m³ of CO2 per year to store. The room exists, at least for a while. (It shouldn't be a shock that those numbers are on the same order of magnitude since natural gas is one of the three principle fuels used to create CO2.) You seem to have a lot of fear and doubt, but I suspect you've never really looked into the technology in serious way. It's not as scary as you seem to imagine, and has a lot of potential for near term mitigation. Dragons flight (talk) 07:14, 10 September 2008 (UTC)

Well, one of the sources of FUD is that these solutions will presumably be provided by private corporations, who will sell their sequestration services for a profit. And when their CO2 reservoir fails (especially if they have over-pressurized them by the 20/3 ratio you allude to above), there will be human deaths near the failure zone, there will be no corporate assets left to claim in the damage suit other than the broken CO2 storage reservoir, and all the CO2 will be back in the atmosphere. Yeah, there is some doubt there. But whatever, lets forget about that old energy conservation idea - that was hippy talk anyway. Franamax (talk) 07:25, 10 September 2008 (UTC)

That 20:3 ratio (as scarey as it is) is nothing like the right ratio though. It assumes that we can efficiently remove the CO2 from all of the other gasses that come out of the power station (or whatever). Since the air used to fire the power plant is only 1/5th oxygen - and the rest nitrogen, most of what comes out of the power plant is nitrogen. If you try to pump all of the exhaust gasses into your underground store then the ratio isn't 20:3, it's more like 100:3. Separating out the CO2 from the nitrogen is difficult and requires an enormous amount of energy...which in turn means generating even more CO2 than we do now. Conservation and renewable are by far the best route. SteveBaker (talk) 18:13, 10 September 2008 (UTC)

Actually, removing CO2 from a vapour stream is relatively straightforward, at least in gas processing it's done with an amine absorber. I have no great idea on the energetics though, nor what size of vessel you would need to process the output from a power station. Or if that's even the scheme one would use at a power plant. Also, amine contaminates easily, is a high-foaming service, and is deadly poisonous. But anyway, it selectively removes CO2! Franamax (talk) 03:39, 11 September 2008 (UTC)

follow up question

Is growing algae at power plants a good alternative to ocean or well storage when reclaimed water from septic systems is used as well?

detectors

what is the job of muon chamber in detectors —Preceding unsigned comment added by 121.52.155.50 (talk) 05:22, 10 September 2008 (UTC)

Are you talking about a muon detector? It detects secondary muons produced by cosmic rays. Applications may include geophysical exploration by measuring absorption by rock in various directions. Graeme Bartlett (talk) 05:35, 10 September 2008 (UTC)

Or are you talking about the Compact Muon Solenoid in the LHC? Muons are emitted from the experiemnts or formed by decay of other particles, and can penetrate further and last longer than most of the other high energy particles. These can be detected further out form the core. Look at this for how this works and what it is used for. Graeme Bartlett (talk) 05:47, 10 September 2008 (UTC)

A hypothetical Higgs boson emits four muons. Graeme Bartlett (talk) 10:11, 10 September 2008 (UTC)

Bayhawk?

What kind of a bird is a bayhawk? 71.113.3.76 (talk) 06:32, 10 September 2008 (UTC)

You might perhaps wish to consider typing "bayhawk" into the search box on the left side of the page. I think you would be pleased with the results. -- Captain Disdain (talk) 08:08, 10 September 2008 (UTC)

CERN's experiment

Anyone knows the exact time when they'll start the experiment? -59.95.99.160 (talk) 06:32, 10 September 2008 (UTC)

It should be just about no

The high intensity experiments aren't coming until the end of the year. Plasticup ^T/C 07:20, 10 September 2008 (UTC)

MSN just a a front-page piece about how the LHC might destroy the world (not kidding). Times like these I have an even lower opinion of the media in general.... --mboverload@ 07:25, 10 September 2008 (UTC)

i'd be more concerned about one of those 30 ton magnets with a defective mounting bracket. Gzuckier (talk) 16:38, 10 September 2008 (UTC)

I'd say they're just doing the 'end of the world' thing for publicity now (or at least not stopping it). Nadando (talk) 01:21, 11 September 2008 (UTC)

High Intensity o.O -59.95.99.160 (talk) 07:25, 10 September 2008 (UTC)

I like todays image at http://www.google.com/ PrimeHunter (talk) 10:57, 10 September 2008 (UTC)

Is the word "Google" being sucked into a mini black hole in today's logo? :-) Fribbler (talk) 12:38, 10 September 2008 (UTC)

The world will not end because of the LHC. CERN has prevented such an accident by preemptively destroying the Earth. [1] — DanielLC 16:14, 10 September 2008 (UTC)

it's all part of cern's plan. by creating the web, they led to google; so that when the earth gets destroyed by a black hole, a digital archive will still exist. Gzuckier (talk) 16:37, 10 September 2008 (UTC)

Thanks for the link. Very calming. Like the end of On the Beach. Saintrain (talk) 16:49, 10 September 2008 (UTC)

hair dryer voltage dilemma

i bought a dual voltage hair dryer for travelling. it has a black switch on the handle where it allows you to choose 115V or 230V by turning it w/ a screw driver or a coin. where should it be when in the US???? —Preceding unsigned comment added by 68.97.36.155 (talk) 06:34, 10 September 2008 (UTC)

115V in the US, for sure. 230V is for Europe and you will need a little plug adapter to go between NA flat plugs and Euro round also. Franamax (talk) 06:47, 10 September 2008 (UTC)

Please could more regulars chime in to emphasize that 115V is the correct setting!? Franamax (talk) 07:33, 10 September 2008 (UTC)

As stated in our article on Mains power systems, this is indeed the case. -- Captain Disdain (talk) 08:05, 10 September 2008 (UTC)

Also note that the 115V setting will be correct in bathrooms of many hotels in Europe that cater to Americans. Just look for the "110" or similar label and U.S.-style plugs. I've been surprised how common this is.--Scray (talk) 10:29, 10 September 2008 (UTC)

Yup, have those in Ireland. We call them "shaver sockets", like this one. Fribbler (talk) 12:18, 10 September 2008 (UTC)

115V in North America. Check out this map [2]APL (talk) 13:14, 10 September 2008 (UTC)

Agreeing with 115 volt setting for North America. Edison (talk) 15:10, 10 September 2008 (UTC)

absolutely correct. you will probably not see a 220 volt outlet during your travels in the US and Canada, and if you should perchance find one, it won't accept the normal north america plug which presumably you have for your shaver. Gzuckier (talk) 15:20, 10 September 2008 (UTC)

Only place one is likely to find anything other than 115V in US houses is sockets specifically designed for heavy-duty appliances (electric clothes dryer, electric stove, air conditioner). And the sockets are usually shaped differently so that you can't plug the "wrong" thing (something designed for 115V) into them. DMacks (talk) 16:20, 10 September 2008 (UTC)

I thought the 220v outlets in the US were some kind of funky three-phase arrangement though. I don't think you could plug a euro-style 220/230/240 volt gadget into one of those even if the plug did fit. There are also concerns over the frequency shift (60Hz in the USA, 50Hz in Europe) - most devices don't mind but my 110v laptop charger severely overheats in Europe when I plug it into my 240v to 110v converter widget. I believe that could only possibly be due to the frequency change. SteveBaker (talk) 17:56, 10 September 2008 (UTC)

As a general rule, anything with a transformer or motor can be used on 60Hz electricity if it was designed for 50Hz, but you can't go the other way around: the magnetic field will saturate, and will stop being an inductive load and start being a short circuit. --Carnildo (talk) 20:32, 10 September 2008 (UTC)

Standard 240 V (not 220 V) outlets in North America deliver two opposite phases of 120 volts plus neutral. This is not 3-phase power, but it does mean that there are two live slots. A European device would expect one live and one return wire, like a North American 120 V outlet, so the regulations would be different regarding safety insulation. (This is all in addition to the safety ground (earth) wire.) Outlets for 3 phase power also exist but are not found in homes. Just to further confuse things, some places in North America use two phases of 3-phase power, thus delivering 120 V between one phase and neutral but 208 V between two phases. This is most common in larger buildings, including some apartments.

As to frequency, resistive applications (heaters, traditional light bulbs) don't care, but transformers do care (as Carnildo says), some types of motors do, and some types of electronics do. If the hair dryer is dual voltage then very likely it will also be marked as taking either 50 or 60 Hz, in which case there's no problem, but you may notice the blower motor running faster in North America. --Anonymous, 20:40 UTC, September 10, 2008.

Modern portable hair dryers, especially dual-voltage hair dryers, use a small dc motor to drive the blower. The voltage for the motor is derived from a "tap" on the heating resistor (with the voltage divider ratio set to produce, say, 12 VAC. This voltage is then fed through a bridge rectifier and thence to the DC motor. This arrangement is advantageous because it's: 1) Cheap; 2) Very compact; 3) Easily accommodates the voltage-switching arrangement; 4) Is completely insensitive to frequency; 5) Allows the motor to turn much faster than the 3000/3600 RPM that an ac induction motor could turn. And did I mention that it's cheap ;-) ?

Atlant (talk) 16:06, 15 September 2008 (UTC)

The device being operated would not know whether it had 240 volts on one wire and zero on the other, as in the UK, or 120 volts from ground on each supply lead with 240 between them as in the U.S. A motor winding, a bulb filament, or a heating element would still have 240 volts across it (or 230 volts at the anemic Euro standard voltage). The ground wire is just along for the ride, there to carry fault current only if there is a breakdown of insulation, and does not normally carry load current. Due to various faults and opens which can occur, either of the supply leads in either country could find itself energized at 240 volts from ground, and would have to be insulated accordingly. Edison (talk) 01:18, 13 September 2008 (UTC)

Now wait a minute, if the two wires are +120V and –120V (i.e., each is 120V AC offset by 180° phase), that certainly gives 240V AC between them just like a 240V and 0V pair. However, how could a line that varies between –120V and +120V "find itself energized at 240 volts from ground"? I thought all the absolute voltage measurements were compared to ground defined as 0V? DMacks (talk) 18:10, 13 September 2008 (UTC)

Ah, so that's why so many things in industrial things are 208V! Always struck me as a weird number to get from the same power distribution system that gave 120V. DMacks (talk) 00:18, 11 September 2008 (UTC)

Star vs. delta 3-phase wiring

You get it when your three-phase system is wired in the star-configuration. 120V from the centre to the outside, between outside points = 2 x 120V * sin(120) (the voltages at each "point" of the star are 120 degrees out of phase). I'd link an article but I can't find any good links for delta/star three-phase - and I've been burned enough lately that I'm not going to complain about it either, someone will just point out my spelling mistake! :) Franamax (talk) 03:23, 11 September 2008 (UTC)

This has been a very illuminating answer. Edison (talk) 03:35, 11 September 2008 (UTC)

boiling water in the states

hello wikipedia, Once of the (many) reasons i find americans endlessly fascinating is that they don't use kettles. As work is going really slowly today, i thought i'd just ask, if you gyus wanted to boil water for cooking (pasta, potatoes etc) what would you do, just put cold water on the stove and heat it up from scratch? Does this not drive you crazy? thanks217.169.40.194 (talk) 08:18, 10 September 2008 (UTC)

An electric kettle can boil the water faster than a gas stove. Its even quicker if you heat a third of your water on the flame, and two thirds of the water in a kettle and then combine them. But simpler if you don't use a kettle at all. Do Americans call a kettle by a different name? Graeme Bartlett (talk) 10:09, 10 September 2008 (UTC)

I'm the American child of East-coast American parents, and we've always had (and called it) a kettle. Same for my wife, a native of California. I think someone is over-generalizing here. Perhaps we need a WP:RS.--Scray (talk) 10:34, 10 September 2008 (UTC)

Non-use of kettles is fascinating? I can assure the OP that some, possibly many, Americans do use kettles. We have the plain kind that you plop onto the stove; we have the electric kind. In bygone days, people left filled kettles on wood stoves or coal stoves to provide some humidity in the winter. (More recently, people bought cast iron kettles to do the same in a retro kind of way, only to learn that cast iron isn't a great idea for holding water over long periods of time.)

My guess would be that most people here cook pasta or potatoes by boiling the water in a large pot on the stove (like a stockpot or a large saucepan). A related guess is that many kettle-users drink tea; people who drink mainly coffee will tend towards coffeemakers.

I agree with the Tea assumption. My aunt lives in Italy, and had to get a kettle shipped over from Ireland to make the sacred brew. In Italy, being very much a coffee country, kettles were nearly impossible to obtain! Fribbler (talk) 12:24, 10 September 2008 (UTC)

As for being driven crazy, we have so many options here that the agony of waiting for pasta water to boil doesn't enter into it. (By "kettle" I'm referring to a vessel with a spout -- e.g., teakettle. Another usage is for a large, open vessel, as in "a different kettle of fish," whence also "kettledrum." Without that kind of kettle, there'd be no cartoons with explorers or missionaries being prepped for dinner.) --- OtherDave (talk) 10:56, 10 September 2008 (UTC)

The big thing with the missionaries is a cauldron. DuncanHill (talk) 15:31, 10 September 2008 (UTC)

It's significantly more energy efficient to use a kettle, which is something Americans have never been too concerned with (just look at average fuel consumptions of cars in the US compared to Europe, say). That may have something to do with the different practice on the other side of the pond. --Tango (talk) 11:34, 10 September 2008 (UTC)

I agree with OtherDave. For one, I would call it a tea-pot or tea-kettle. Simply saying "kettle" needs context to know whether you meant for making tea or if you meant something that Elmer Fudd would boil Bugs Bunny in for stew. For two, everyone I know would likely use a large sauce pan or pot to boil water in for potatoes or pasta. And lastly, I would put a lid on the pot in order to save energy and time. Dismas|^(talk) 12:25, 10 September 2008 (UTC)

Electric kettles are very handy for a cuppa. I assumed that the reason they were so fast is the 250V. What is the wattage of a UK e-kettle? Saintrain (talk) 12:34, 10 September 2008 (UTC)

2-3 kilowatts [3]. Fribbler (talk) 12:36, 10 September 2008 (UTC)

To avoid confusion, note that (in the UK at least) teapot and kettle (never heard it called a "tea-kettle") are different objects. You boil water in a kettle, then pour the boiling water into a teapot together with tea leaves or tea bags to make tea. Gandalf61 (talk) 13:06, 10 September 2008 (UTC)

Good thing you don't have Carolina Wrens over there. You'd have no idea what they were talking about. -- Coneslayer (talk) 13:11, 10 September 2008 (UTC)

When you say "kettle", are you referring exclusively to a "teakettle"? (With a spout and everything. Probably a whistle, too.) Because that's all the word "kettle" means in USA. I notice that the article mentions that it could have a wider meaning in the UK.

For completeness, what would be the pasta making procedure in, say, England? Would you pre-boil some or all of the water in a teakettle before transferring it to a pot? That seems like a good amount of extra effort. APL (talk) 13:12, 10 September 2008 (UTC)

As an energy-conscious German, yes, I pre-boil water electrically before filling into a pot, be it for rice or pasta cooking. You'll do that too as soon as you pay as much for energy as we here do. --Ayacop (talk) 13:44, 10 September 2008 (UTC)

I did manage to find a store in Texas that had electric kettles - they aren't easy to find though. It's really crappy by UK standards - but it works. IMHO, the way you heat water depends on the amount. For small quantities (eg to make a cup of coffee), I use the microwave oven. It's faster than a kettle and vastly more energy-efficient. For medium sized quantities (eg to make four cups of coffee), I use our Texas kettle. At those quantities, it's more energy-efficient than the microwave and faster too. For larger quantities, I use the stove-top and a saucepan - more for speed than for energy efficiency. If I had a larger kettle, I'd use that. SteveBaker (talk) 13:37, 10 September 2008 (UTC)

The Utah teapot - very important to computer graphics geeks!

When you say "tea kettle" in the USA, you're typically imagining an approximately hemispherical vessel with a flat bottom that you set on top of the stove. When we say "kettle" in the UK (they aren't "teakettles") - we know about the US thing - but we're more likely to be thinking of a large cylindrical pot with an electric heating element in the bottom that can boil a couple of pints much more quickly than you could ever do on the stovetop - and with better efficiency too. The fancy modern ones have dual elements for greater efficiency and little float gauges on the side to indicate how full they are. They typically have "curly-cord" power connections (like a short telephone cord) for kid-safety, auto-shutoff when they boil, maybe have a beeper to replace the old whistle. They are sophisticated, highly evolved machines - compared to an American tea-kettle: think "Ferrari versus Trebant". A "teapot" is a (typically) ceramic pot with a spout and a lid in which the tea is actually brewed - you don't ever heat the water in a teapot.SteveBaker (talk) 13:47, 10 September 2008 (UTC)

• widths="100px"
• 
  Kettle
• 
  Teapot

More pictures above .... Gandalf61 (talk) 13:51, 10 September 2008 (UTC)

Some of us Americans might be more likely to refer to the electric water heating apparatus as a "hot pot," as can be seen by the category name in this Amazon listing. Personally, when I need to heat water for tea, I use the quintessential Revereware kettle; if it was good enough for both my grandmothers, it is good enough for me. Personally, I had a hard time searching for a tea pot that I liked, but that's another story. --LarryMac | Talk 14:16, 10 September 2008 (UTC)

The Revereware kettle looks like the sort of thing one would take camping. A few people in Britain still use such kettles on a gas hob at home. DuncanHill (talk) 15:33, 10 September 2008 (UTC)

as a bonus, when attack by redcoats is imminent, the whistle blows "the british are coming!" and it prepares a cup of tea for them. Gzuckier (talk) 16:34, 10 September 2008 (UTC)

The one and only electric kettle we've ever found here in Texas looks pretty much exactly like one of those - except it has three little rubber feet underneath and a wire coming out of the back! SteveBaker (talk) 17:38, 10 September 2008 (UTC)

I've used an electric kettle in the UK to boil water, and it does a fine job on the 240 volts available in the wall outlet. But in the US the voltage is half as much, and the appliance amperage is usually limited by the 15 or 20 ampere rating of the circuit, so it takes a long time to boil water with an electric kettle. Looking at some adverts, the UK kettles seem to have a 3000 watt rating and the US kettles only a 1500 watt rating. A stovetop burner seems to apply more energy to the water and get it boiled faster. Of course someone could have a 240 volt outlet installed in the kitchen for the electric kettle, but this would be very unusual outside a restaurant. 3000 watts would be 10,240 BTU per hour, and stovetop range burners can be had with 15,000 BTU per hour and higher rating. Granted, the electric kettle should apply the energy to heating the water more efficiently than a kettle setting on a range burner. A microwave might have just a 1000 watt rating. Edison (talk) 14:58, 10 September 2008 (UTC)

What you're missing with the microwave part of that is that the microwave only has to heat up the water and some kind of container (which in many cases is the container you're going to use for the drink anyway). An electric kettle has to heat up that large metal element too - and when you pour the water out, a lot of heat energy remains in the kettle itself. That's why the microwave is a more energy-efficient solution. Also, if you pour the water out of the kettle into a cold ceramic cup - then the cup cools the water down. With the microwave, the cup is also heated - but that energy isn't wasted. The stovetop is even less efficient for much the same reasons - but also the thermal connection between the heater element and the water inside the pot is a very poor one compared to having the electrical element immersed directly into the water...hence yet more energy goes into heating up the air and the metal stove top. That's why the microwave is the most efficient way to heat water (and also the fastest if the quantities are small) - the electric kettle comes second and the gas/electric stove-top is (by far) the worst.

Yet another problem with kettles and stoves is that while the water is heating, oxygen and nitrogen come out of solution and stick to the sides of the container. As it comes close to boiling, steam bubbles do the same thing as the water closest to the heat source reach boiling point long before the rest of the liquid. Those bubbles are extremely good heat insulators and prevent much of the heat transferring into the liquid - allowing the heating surface to (uselessly) get hotter than 100degC. Microwaves (by their very nature) only heat the water itself - so 100% of the energy goes into the water. You might think this is a negligable effect - but it's really not - and I can prove it (albeit indirectly)...

If your car engine is overheating, you can sometimes get it to run cooler by flushing out the antifreeze and replacing it with plain water. That's because plain water conducts heat better than ethylene glycol. However, this steam-bubble formation issue strikes because the boiling point of water is lower than the glycol/water mixture and the water may boil as it passes through the engine block causing localised hot spots that can actually ruin your engine...maybe even crack the block. There is stuff you can buy called "Water wetter" that lowers the surface tension of the water and raises it's boiling point WITHOUT reducing it's thermal conductivity that fixes this problem entirely.

I agree that the lower mains voltage/current is the likely reason why electric kettles aren't popular over here though...although I have 240 volts going to my cooker - it wouldn't take much to wire up a UK-standard 3 pin plug...hmmm - it's tempting!

SteveBaker (talk) 17:38, 10 September 2008 (UTC)

UK mains is generally fused at 13 amps, so if you have up to 20 amps that compensates for the lower voltage quite well. 115V at 20 amps gives a maximum of 2.3kW, plenty for boiling water (it's the cheaper end of the UK kettle market, but it'll do just fine). Rather than talking about all these meaningless numbers, let's try some meaningful ones - it takes about a minute to boil a couple of pints in my kettle (far less to boil a mug full for a cup of tea/coffee). How long would it take on your hob (or "stovetop" or whatever you call it)? --Tango (talk) 15:19, 10 September 2008 (UTC)

Just pointing out the UK mains electricity has been delivered at 230 volts rather than 240 volts for something like the last 10 years. To harmonise European standards, those continental supplies that were on 220 volts have been or are in the process of being upped to 230 volts. I seem to remember some spurious talk at the time of the changeover that it would affect the economy because it would take longer to boil a kettle and people would take longer tea-breaks. It would also make you late for work because it would take longer to make toast. Jooler (talk) 15:21, 10 September 2008 (UTC)

Well, it's 230V +/- 10%, so that's anywhere between 207V and 257V, so the change from 240 to 230 is less significant than the natural variation anyway, so I don't think you can use that as an excuse when you're late for work! --Tango (talk) 15:49, 10 September 2008 (UTC)

Hmmm - I always thought the change was not one of the actual voltage provided - but a change from quoting the peak-to-peak voltage to talking about the RMS voltage in order to comply with Euro measurement standards. I guess I'm wrong on that score then! SteveBaker (talk) 17:46, 10 September 2008 (UTC)

decadent capitalists not inwenting samovar!! Hahahaha! Gzuckier (talk) 15:23, 10 September 2008 (UTC)

I'm a (naturalized) American, so I'll just answer the question as a data point: if I want to boil water for pasta, I take my 4 dogs' communal water bowl, run the hot water tap into it until the water is hot, then fill a thin-metalled pot with the hot water, put some salt in, and put it on my gas range. It's usually boiling within a couple of minutes. --Sean 00:13, 11 September 2008 (UTC)

You cook with water from the hot tap? Isn't that supposed to be a really bad idea because it's been sitting in a warm tank and pipes for god knows how long? Boiling it may kill off the vast majority of germs, but it won't remove anything that's dissolved in it (hopefully you don't still have lead pipes, or that could be really nasty!). --Tango (talk) 14:14, 11 September 2008 (UTC)

Most houses in the US use either copper or plastic for the pipes, and you're supposed to keep the hot-water tank at 140F or above, hot enough to kill anything dangerous. --Carnildo (talk) 21:08, 12 September 2008 (UTC)

According to this page, the CPSC recommends a setting of 120F, for burn safety. I guess you can't make everyone happy. -- Coneslayer (talk) 01:35, 13 September 2008 (UTC)

boiling a cup of water

on a related note, whatever happened to those little plug in one cup heater uppers? (let alone the immersion heaters) i can't find any for 110 volts any more, only 12 volt car ones. i'm toying with hooking one up with an old gel cel 12 volt battery and a wall wart, just so's i can get a cup of hot water for beverage purposes at work. Gzuckier (talk) 15:26, 10 September 2008 (UTC)

This [4] would do for making instant coffee, but as it does not actually boil the water is unsuitable for making tea. I would add that as one can buy a perfectly serviceable ordinary electric kettle for a fiver, it does not look like good value for money. DuncanHill (talk) 15:40, 10 September 2008 (UTC)

Or you could take a thermos of your favoured drink to work. DuncanHill (talk) 15:54, 10 September 2008 (UTC)

yeah, but i'm looking for something highly unobtrusive. otherwise the Corporate Preventers will spot it and break into one of those "whatever it is, I'm against it!" routines that they do so well. that's why i've been holding off on the battery/12 volt mug approach.Gzuckier (talk) 16:31, 10 September 2008 (UTC)

Somewhere on the interweb I saw a USB-powered coffee maker - the USB charges a battery inside that actually heats the water. I'm not sure that helps the issue with the Corporate weenies being a pain. It would be kinda neat on a back-packing holiday though: "I sure could use some hot coffee right now."..."Sure, I'll go grab my laptop and be right back!". SteveBaker (talk) 17:46, 10 September 2008 (UTC)

Speaking of which this was a great solution for us to run a USB hub in -25 C ice core lab. It's hard to find cheap, cold-rated usb hubs, but you don't have to if they have a built-in heater. ;-) Dragons flight (talk) 17:57, 10 September 2008 (UTC)

<soapbox warning>I just want to say that I haven't had so much fun since I first came to Wikipedia. Even with the U.S. / U.K. differences, none of the armed-Talmudic screeds about those with disagreeing opinions.</soapbox>

I was born in Canada but raised in the States, and my parents have always had a (non-electric) kettle (for the boiling) and a metal teapot (for steeping the loose tea leaves and leaving on the stove with just a smidgin of heat).

I think the energy-conscious comments are apt; we're still bellyaching about gas costing $3.50 a gallon.

You can find electric kettles (other than the venerable Hot Pot) here, but you have to look hard, or else go to Canada.

I agree completely with the need to have boiling water for tea (and with the need not to have the word "Lipton" within 500 yards), which is why visitors to the U.S. who are in their right minds never order tea, except perhaps in some non-chain college-town coffee boutique. --- OtherDave (talk) 13:21, 11 September 2008 (UTC)

UK Spiders

What is the name of those orangey-brown and white spiders that become so prevalent in the UK on cold September mornings? Little blighters were all over my car this morning... sparkl_!sm ^hey! 08:57, 10 September 2008 (UTC)

Are they like this at European garden spider? Julia Rossi (talk) 08:21, 11 September 2008 (UTC)

Yes, that's the fella, thanks! Does anyone know why they become so plentiful in early September? sparkl_!sm ^hey! 20:49, 11 September 2008 (UTC)

MEDICINE:GYNAECOLOGIST

What subjects do i require in high school for me to become a GYNAECOLOGIST?Mrs.Rushaksy (talk) 12:06, 10 September 2008 (UTC)

Gynaecology is a medical speciality. So the course you would be taking at third level is medicine. As I understand, in the US (you said high school, so I'm guessing you live there) medicine is a graduate-entry course in that you must first have a relevant degree in say Biology first before you can do medicine. So Biology and Chemistry would be the subjects best suited to pursuing this first degree. Fribbler (talk) 12:14, 10 September 2008 (UTC)

If you truly want to be any sort of specialist, this is a suggestion that I've seen work with many people since I've been working in the medical field:

1. Start volunteering at your local hospital now. You will be doing junk work with no (or very little) pay. But, you will be around doctors and get used to hearing medical-speak. You may realize that you hate the profession and change your mind.
2. Take all the biology and physics that you can in High School. If yours is like mine was (white-trash redneck tiny-town school), you'll have to take classes at a local community college instead of high school.
3. By your senior year, pick the medical schools you want to go to. They will have "sister colleges" that offer the pre-med courses. Now, you know what undergraduate colleges you want to go to. You can work on getting into them.
4. As an undergrad, continue volunteering at the medical schools you want to go to - including applying to do any work you can in research projects. You'll get paid for that work. The goal here is to get your name known with as many people in the school as possible.
5. As you near the end of pre-med, study and study and study for the MCAT. Your score on the MCAT will be a major factor into getting into med school as well as getting free funding for the school.
6. Assuming you do well on the MCAT, you'll be accepted to the medical school. You'll be a general medical student (specialist courses don't matter at the beginning). Try to get an advisor that is in the field you want to work in. He or she will guide you through the courses you need and possibly get you into a volunteer position in the field.
7. From that point, you are set - do well in your classes, keep volunteering, and all those years of working for no pay will finally pay off as you will have the education and the years of experience to bubble up to the top of your class and get a good job anywhere you like.

Keep in mind that that is only one way to do it. You could just have rich parents to donate a building to the medical school in exchange for a degree. -- kainaw™ 12:48, 10 September 2008 (UTC)

Also: you're in high school, so please forgive me if your intentions are pure, but, speaking as a one-time high school boy, let me advise you that if you're thinking that this is a good way to see lots of vaginas, I can't tell you how wrong you are. Under no circumstances should you (or anyone else, for that matter) click on this link: Google image search for "diseased vaginas". --Sean 01:10, 11 September 2008 (UTC)

physics

whether man can run fast or slow on moon.Plz explain with respect to on earth

—Preceding unsigned comment added by Khubab (talk • contribs) 17:13, 10 September 2008 (UTC) 

Not fast in short distances, because each step takes you away from the surface for too long, so you can't accelerate fast enough. Long distance is different because no friction happens while in the air, but I'd guess it difficult to accelerate further when already at high speed. --Ayacop (talk) 17:24, 10 September 2008 (UTC)

An additional problem for lunar hiking is one of mass. An astronaut must haul around a substantial portion of body mass in life support equipment. While the weight of all this is fairly low (with the 1/6g at the lunar surface), its mass and inertia is unchanged. It's much harder to start, stop, or change directions on the moon than on Earth. — Lomn 18:00, 10 September 2008 (UTC)

An Earth-bound similarity is the high-speed cars that try to break ground-speed records. The ones that use tires as propulsion have to deal with the friction between the tire and the ground. If they gun it at the start, they spin out and don't move much. That is a lot of wasted fuel and energy. So, they start slow and build up speed. At high speeds (around 300mph), the tires no longer have the ability to push the car forward. They just spin out if any attempt to accelerate is made. So, the car has reached a top speed, not based on the engine, but based on the tire's friction. Translate that to a man on the moon and you have the situation explained by Ayacop. -- kainaw™ 18:03, 10 September 2008 (UTC)

A perhaps-similar question was answered empirically in the greatest scientific experiment in history (before the LHC, of course): can you swim faster through a swimming pool full of syrup than through one of water?--Sean 01:20, 11 September 2008 (UTC)

Much much much faster. Drag force is $D=.5*C*rho*A*v^{2}$ and just as sprinters lean into a curve by about 10-degrees, a sprinter could lean forward almost 45 degrees if running on the moon and reach incredible speed and without falling forward. They would have a huge advantage not only in decreased drag force, but could have a much more beneficial angle to use their feet to push against the ground (assuming they have good shoes, on a concrete or asphalt surface for example). Also if you notice the drag equation, rho is the air density (or fluid density) so if you reduce this by about 90%, you could triple your velocity. Also, this assumes you train for several days, getting used to the new feel and nuances of sprinting on the moon. Sentriclecub (talk) 09:54, 14 September 2008 (UTC)

light

Does light acclerate on approaching a black hole? —Preceding unsigned comment added by 117.197.209.41 (talk) 17:49, 10 September 2008 (UTC)

No (provided the area around the black hole is a vacuum). Gravity can affect the trajectory of light but not its speed. — Lomn 17:56, 10 September 2008 (UTC)

Which is a "yes." I agree that the black hole does not change the speed at which light travels, but remember that a change in direction, even at constant speed, is also an acceleration. Chuck (talk) 21:24, 10 September 2008 (UTC)

While true, I doubt this is the context in which "accelerate" was used. — Lomn 21:34, 10 September 2008 (UTC)

It is, however, blueshifted. --Tango (talk) 18:05, 10 September 2008 (UTC)

Not from where I'm standing (I hope). Saintrain (talk) 19:17, 10 September 2008 (UTC)

If you're standing somewhere a significant distance from the black hole (as I would hope you are, seeing as I'm on the same planet as you!), you won't be able to see any light approaching the black hole, since you would need to be inbetween the light and the hole. --Tango (talk) 14:19, 11 September 2008 (UTC)

CERN AL-Zanders' dropping some mighty LHC yo!

That's science-ghetto-geek talk for my own reference of one: CERN, and two: the Large Hadron Collider.

Question: Will this effect the way we make toaster ovens?

Meaning, do we the little people of science know the uses this collision will do for us in the proletariat section?

Not the Little-Black-Hole-Bang talk, but on a slippery slope, could this be a stepping on a butterfly, as in the Effet de Papillon?

Cheers,--i am the kwisatz haderach (talk) 17:51, 10 September 2008 (UTC)

Wikipedia is not a crystal ball. It cannot be used to tell the future. If you are asking for references (as this is a reference desk), a search of periodicals at all three local universities shows absolutely no hits on articles containing both "hadron collider" and "toaster oven". -- kainaw™ 17:56, 10 September 2008 (UTC)

He is asking if any of the LHC research will do anything for your average joe. Plasticup ^T/C 18:24, 10 September 2008 (UTC)

instead of mountain climbing you can go wind surfing on a lake, the positive side, for the average Joe, the problem with rising sea levels is solved.Mion (talk) 18:48, 10 September 2008 (UTC)

So, we split the atom, then blew up folks with some a-bombs. I'm just saying, what are the negatives and positives, most likely the negatives that cripple mankind will be extorted first. Considering history. Ok, simply: We collide some Particles. Okay., and the point is??? That's the question. The answer I take from the round abouts is, "We'll all see when it happens." And that's an alright answer. So the premise is, we can do something we have never done before, to our collective memory of 4000 years, but we don't really know what we're doing. And that's ok. But if any scientists here actually know some simple E=mc2 answer, Energy equals Mass, what of it? Is this to understand Mass more? Understand Energy? Yes, we are Technological here, yes, we have some smart answers w/ or w/o sarcasm. But brass tacks: What are we doin' here with this LHC? 'Explain your answer to a 12 year old.' <--true sciences. Please. Cheers, --i am the kwisatz haderach (talk) 19:19, 10 September 2008 (UTC)

LHC is a tool that will be used to examine subatomic particles and the forces with which they interact, and to study some areasa of physics where certain theories were not testable experimentally until now. It's a basic-science thing, not an engineering/applied-science "build a better mousetrap" goal. One could certainly speculate about new devices that could be built using whatever exotic stuff they find, but that's...speculation, even on the part of those actually doing the experiments (who no doubt had to somehow justify this hugely expensive special-purpose gadget to numerous governments and scientific agencies). DMacks (talk) 19:29, 10 September 2008 (UTC)

It's unlikely the LHC will have any benefits to individual consumers, if that is what you are asking. It is likely that the biggest overall benefit to society will be in the form of keeping a lot of scientists on the payroll in general, and of those scientists a certain number will eventually come up with something helpful or practical. Many of the scientists will gain in prestige from their work with the LHC, which will help them get future funds, and the whole cycle continues. There's always the rare, rare chance that something will directly come out of work like this but it doesn't happen very often, and I don't think anyone's expecting it to happen here. Big Science is as much about creating a Big Infrastructure as anything else, which can serve as an end to itself. That being said, there's a strong argument for, "surely we could spend the money better elsewhere" which might be true, though frankly most governments burn through money in the most inefficient ways anyway, and the amount of money spent on the LHC is a drop in the bucket. --98.217.8.46 (talk) 19:40, 10 September 2008 (UTC)

Thanks much. Digression: There's a really cool video game at the time, late 90's-Early 00's(Early Zeros), that had this Science David Banner-like guy going into the CERN or CERN like particle accelelerator. Opens a mini-black hole, another dimension of time and space, then you go about on this adventure. End of game you come back chasing a villian, I think you end up blowing him up, more imploding him up with the facility. I forgot the name of the game, but it was fun. And the first time I heard of a Particle Accelerator. And I think there was a Jean-Claude Van damme movie with one in it. Reading more about it I see the basic-science questions of MORE INFO on the DarkMatter/Energy thing, Matter/Antimatter, GUT, etc. GO SCIENCE!!! --i am the kwisatz haderach (talk) 19:44, 10 September 2008 (UTC)

Just a question, is there some news on Composite Fermions ? Mion (talk) 19:57, 10 September 2008 (UTC)

In case the 12 year old doesn't follow all that, the idea of the Large Hadron Collider experiment as I understand it is to whip some incredibly tiny particles up to incredibly high speeds and then let them crash into each other, to see what happens and perhaps learn something about the universe.

The experiment is not considered dangerous because the amount of energy involved in each "crash" is not quite enough to run a 60 watt light bulb for a second.

(That is if I did the calculation correctly. Perhaps someone will check it.) Wanderer57 (talk) 20:00, 10 September 2008 (UTC)

The 1991 video game I referred to earlier is called 'Out of this World'. A great 2D game, with exceptional graphics for that time. Wikis, mosdef check this one out. You'll like it. Tschuss, --i am the kwisatz haderach (talk) 20:42, 10 September 2008 (UTC)

It's testing a scientific theory. Science isn't just going around saying "what if?", it's going around saying "why's that?". Once there's an understanding of "why" then there can be predictions of "what else".

There are precise predictions of what's going to happen during the collisions, based on the current (prevalent) model of how the world works. The predictions will be borne out, confirming the model, or they won't, providing new insights into how the world works. If confirmed, researchers will have greater confidence in the predictions that will lead to engineering advances.

There have already been significant output from CERN. The WWW, for one. Knowledge learned through the development of really big magnets may lead to fusion power sooner. (No, not at LHC. Don't start that rumor.)

Einstein's "why's that" lead directly the A-bomb; and to transistors and solar cells and DVDs; and the LHC.

Hubble's to the big bang; see LHC.

Curie's "huh?" lead to the bomb; and atoms and cancer treatments and cat scans.

Pasteur's "why does wine sour?" to pasteurization and antibiotics. He's also directly responsible for much of the population explosion, but population control through food poisoning and plagues seems, well, you know, natural.

Franklin's "what's lightning?"; he got the sign of the electric charge wrong but the vibrator was one of the first "household appliances" to be electrified.

These are just a very few of the famous ones. We've been asking "why's that", and finding the answers, for a long time. Saintrain (talk) 20:54, 10 September 2008 (UTC)

While it's true that science has obviously led to some very practical things, it's not at all been established that pouring billions of dollar into single facilities will do something like that. It's considered pretty unlikely that the LHC will provide any sort of breakthroughs like the ones you have listed above. (And Einstein's work didn't actually lead directly to the atomic bomb, incidentally. Curie's work is a bit more on the mark in that respect—the atomic bomb emerged out of work in experimental work with radioactivity and particle physics, not the sort of fundamental theorizing Einstein did.) --98.217.8.46 (talk) 00:12, 11 September 2008 (UTC)

Well, if you consider the work involved in affixing his signature to a letter ... --Sean 01:29, 11 September 2008 (UTC)

Before that, he pretty much nailed the coffin shut on the "atoms don't exist" thing and his mass-energy equivalence proved pretty handy to Meitner et al. As for predictions, would you please forward tomorrow's FTSE close?  :-> Thanks. Saintrain (talk) 16:07, 11 September 2008 (UTC)

All of you are using one of CERN's inventions, HTML, the internet browser and world wide web. This is a case of scientists working on something not directly related to particle physics, but ending up useful. Graeme Bartlett (talk) 21:20, 10 September 2008 (UTC)

A SCIENTIST MUST SEE; here's a short 2.5 min vid on an example of a Particle Accelerator with a twist of a B.Franklin/M.Shelley Lightning bolt: [World (Out of this World) Video Game Intro] bon jour, --i am the kwisatz haderach (talk) 21:31, 10 September 2008 (UTC)

Somewhat obviously: Specialagent777 why are you posing questions, when as the self-claimed Kwisatz Haderach surely it is us who are supposed to seek your "absolute powers of prescience" and ability to "bridge space and time" - I shall remain severely disappointed in your abilities if you can't answer a simple prediction of what equivalent of "Apollo moon landing effort gave us Teflon non-stick frying pans" we shall get out of the LHC :-) David Ruben ^Talk 22:10, 10 September 2008 (UTC)

Dentistry question: not advice and not homework

Why is it inadvisable to drink alcohol or smoke within 24 hours of a tooth extraction? —Preceding unsigned comment added by 79.76.128.237 (talk) 17:55, 10 September 2008 (UTC)

Smoking has statistically been related to a high number of complications, primarily dry sockets. Alcohol (as well as hot liquids) will dissolve the blood clot and open the wound to the possibility of infection. -- kainaw™ 18:07, 10 September 2008 (UTC)

related to LHC

If by chance the experiment is failed are there any chances of explosion or any harm to human life? —Preceding unsigned comment added by 06riya (talk • contribs) 18:42, 10 September 2008 (UTC)

It's just possible, if something goes very wrong, that they might break some of their equipment. There is no risk to humans. Algebraist 18:47, 10 September 2008 (UTC)

Not true! One human has already been killed by this device (mentioned in the article)! But as Algebraist said, it was from an equipment/breakage accident, not from Particle Physics Gone Wild. DMacks (talk) 19:47, 10 September 2008 (UTC)

Well, yes, someone was killed by having a whole bunch of equipment dropped on him. Since no-one's going to be going into the accelerator while it's turned on, this is no longer much of a risk. Algebraist 00:12, 11 September 2008 (UTC)

Just keep an eye on this. Paragon¹²³²¹ 21:25, 10 September 2008 (UTC)

That's too much work. Just subscribe to the RSS feed. APL (talk) 00:54, 11 September 2008 (UTC)

Yes! One (unlikely) failure mode would be for some part of the machine to explode or start a fire or wildly shoot the proton beam at an innocent bystander. See here for a description of some of the largish energies involved; a full beam could melt a tonne of copper!. That said, there is no chance of it being more dangerous than a good-sized IED. --Sean 01:41, 11 September 2008 (UTC)

@ Paragon & APL: LMAO! There's no way it'll say yes anyway because *common sense*? ~AH1^(TCU) 00:10, 13 September 2008 (UTC)

What is a Hadron

Can anyone explain in simple language (not like the article) what a Hadron really is and what is its definition? I mean is it any thing to do with leptons, bosons and quarks and suchlike? Is it a subatomic particle? —Preceding unsigned comment added by 79.76.128.237 (talk) 19:13, 10 September 2008 (UTC)

Forgot to ask, whats a large hadron. Is it just a proton or neutron? —Preceding unsigned comment added by 79.76.128.237 (talk) 19:16, 10 September 2008 (UTC)

The Large Hadron Collider is a large collider of hadrons, not a collider of large hadrons. -- Coneslayer (talk) 19:19, 10 September 2008 (UTC)

Like they would've got funding if they called it the "Small Hadron Collider"! :) Franamax (talk) 03:07, 11 September 2008 (UTC)

(ec) As it says in the lead paragraph of that article, the best-known hadrons are protons and neutrons, which are subatomic particles. The Large Hadron Collider will collide protons. More generally, a hadron is made of several quarks held together by the strong force. Some hadrons are bosons, others (like protons and neutrons) are not. No hadron is a lepton; leptons are something else entirely, and include electrons. Algebraist 19:20, 10 September 2008 (UTC)

Is there any truth to the rumour that in Ireland the hadrons are small and green and are called leprickons? Wanderer57 (talk) 22:37, 10 September 2008 (UTC)

Yes. --Tango (talk) 22:43, 10 September 2008 (UTC)

I had a small green Hardon hadron once. But the doctor gave me some cream to put on it. —Preceding unsigned comment added by 79.76.128.237 (talk) 23:23, 10 September 2008 (UTC)

Yes, I was tempted to chime in and say it's a dyslexic erection, but that would have been tasteless and juvenile, so I refrained.  :) -- JackofOz (talk) 03:11, 11 September 2008 (UTC)

I had one of those once; it was hadroneous. Kittybrewster ☎ 03:19, 11 September 2008 (UTC)

Does heat contribute to global warming?

Does the amount of heat given off by a machine or organism contribute in any way to global warming?

Say we had nothing but solar-powered cars, but their motors cooked away at 200 deg C, or say everyone had a solar powered air conditioner spewing hot air into the streets, would this affect global temperatures in any way?

Thanks!

— Sam 19:28, 10 September 2008 (UTC)

I believe that would violate the first(?) law of thermodynamics. The energy from the sun is already entering our atmosphere (mostly as heat to begin with); harnessing it and converting it will not directly be a problem. It's conceivable that how we go about it can cause some problems, but I don't think this particular worry is well founded. - Lambajan 19:43, 10 September 2008 (UTC)

It's worth noting that there are two different questions here: "does heat given off by <something> affect global warming?" and "does heat from solar-powered sources affect global warming?" I'm inclined to agree with LambaJan on the latter, but the former is not necessarily true -- the fuel source matters. — Lomn 21:28, 10 September 2008 (UTC)

On second thought, I don't agree with the solar-powered thing, either. Solar cells capture light energy that would otherwise scatter away, converting more of it (eventually) to waste heat. — Lomn 21:30, 10 September 2008 (UTC)

What would be the ultimate fate of the energy in that unused scattered-away light? DMacks (talk) 21:49, 10 September 2008 (UTC)

It heats up whatever it's absorbed by. Some of it will be reflected back into space, but Earth gives an albedo of 0.367, so only 36.7% of sunlight hitting Earth is reflected back, and I believe most of that is from clouds and oceans, so solar cells on land probably don't make much difference. --Tango (talk) 22:46, 10 September 2008 (UTC)

Not much, no -- but if you want to take the argument to extremes, I would expect some difference. — Lomn 23:29, 10 September 2008 (UTC)

The difference would probably be less than the natural variation from changes in cloud cover, etc. --Tango (talk) 00:08, 11 September 2008 (UTC)

(semi-digression) A few jobs ago, we had a bunch of small cartridge heaters that were unlabeled as to wattage. We got pretty close estimates by comparing "how hot does this feel compared to a known-wattage lightbulb?" The net energy coming in eventually becomes heat, regardless of whether it starts "as heat" or "as absorbed light". DMacks (talk) 00:15, 11 September 2008 (UTC)

Cities are hotter than rural areas (the urban heat island), but this effect is mostly caused by buildings blocking thermal radiation from escaping into the sky. There article's "Relation to global warming" section seems to indicate that the heat island has negligible effect on annual temperatures. --Bowlhover (talk) 00:23, 11 September 2008 (UTC)

I've actually had similar thoughts. My current stance is that the heat from the sun trapped by greenhouse gases must be more than we produce on earth, but let me share an experience that frightened me: as a special treat, I drove to vegas for my 21st birthday with my brother and a friend. We went during a chilly week and arrived at night, but as we approached the immmediate outskirts of the city, it got SIGNIFICANTLY warmer. I have no doubts the heat of Las Vegas relative to the rest of the dessert is due to energy used by all the casinos, especially the lights on the strip. Electricity use results in heat. Lightbulbs, TV's, computers, cars, hot water heaters....we are surrounded by heat sources, and our electricity consumption might correlate somewhat with the rise in global temperature. Lambajan mentioned the first law of thermal dynamics, but most of our energy is drawn from coal and petroleum: energy from the sun that was stored long ago and is being released long after the fact en masse. Could ground level heat production effect world temperature? It's possible, But I don't know whether it would be significant relative to other sources. --Shaggorama (talk) 03:58, 11 September 2008 (UTC)

Yes, it has an effect, but no, it is not significant. The solar constant is about 1360 W/m², or 340 W/m² if averaged over the surface of the Earth. Even Vegas is much darker than that. The increased temperature you feel is mostly due to stored heat from the day being re-radiated, from decreased cooling due to the more complex artificial landscape, and from decreased air exchange due to buildings. I felt exactly the same effect you describe when entering Kata Tjuta about a months ago, and there are no external heat sources to blame there. --Stephan Schulz (talk) 08:56, 11 September 2008 (UTC)

With reference to the photovoltaic panels mentioned earlier, you might like to note that they would typically be reflecting more solar radiation back into space than the average albedo of 37% cited earlier. A researcher for a leading PV manufacturer gave me figures a while back of 50% reflected, 15% converted to electricty and 35% kept as heat. This could vary quite a lot though. Efficiency rates are gradually climbing and there are transparent modules available which can be used to replace glazed areas in buildings. If vast PV power stations are to be placed into deserts then the issue would have to be considered. It would probably e better to convert as much of the solar radiation as possible into electricity than to reflect it back into space. But in the solar energy article there is mention of deliberate attempts to increase albedo, simply by painting surfaces white. Itsmejudith (talk) 08:23, 12 September 2008 (UTC)

All the solar radiation that hits the Earth is radiated back out into space one way or another (some of it gets turned into plant matter, but only a tiny percentage). It is either reflected directly as light waves or radiated as infrared heat. It is the infrared portion currently causing our problems with global warming - increased CO2 and other trapping gases absorb the infrared radiation emitted from the ground, that heat energy has to be re-radiated from the upper atmosphere, and a new equilibrium is established at a somewhat higher overall temperature. The amount of energy absorbed from the Sun by our planet is truly vast though, and it is all heading back out. As far as "vast" PV stations in the desert - think about what vast really means. If you covered even one whole desert for solar power, you have covered very little of the Earth's entire surface, and the area doesn't match natural variations in cloud cover and seasonal snow and ice cover. According to our article, the "usable energy" received from the Sun is 8,000 times 2004 human energy use from all sources. By my figures, we need three spots around the globe, 250 km square, carpeted with 25% efficient solar cells, and we're covered. Franamax (talk) 09:33, 12 September 2008 (UTC)

Water injection

If water was injected into the bloodstream, would it cause pain, or worse? —Preceding unsigned comment added by 79.76.128.237 (talk) 19:31, 10 September 2008 (UTC)

No. Blood (and indeed all of you) is mostly water already. Saline injection is standard for treating severe dehydration. Yeah, it's "saline" but only very slightly (not like oceanic salt-water). The main risk for "pure water" would be if huge amounts were injectedf aster than the kidneys (etc) could remove the excess water--then the blood would get diluted and its transport properies would change. DMacks (talk) 19:45, 10 September 2008 (UTC)

Pure water? Yes - painful. Yes - dangerous. I know of a case where sterile water was infused intravenously by mistake instead of saline. And it was extremely painful. It is also dangerous, because the lowering of the osmolarity of the plasma may lead to hemolysis, and well as damage the endothelium. Large quantities? Lethal. --NorwegianBlue ^talk 20:53, 10 September 2008 (UTC)

Okay yeah, didn't think about local effects for pure water:) DMacks (talk) 21:33, 10 September 2008 (UTC)

What local effects? Wouldn't it diffuse into the blood stream pretty quickly? --Tango (talk) 00:07, 11 September 2008 (UTC)

Meaning the lysis of red blood cells exposed to that pure water before/while it was diffusing. So a drop or two no big deal (and even if you lose "only a few" cells, probably wouldn't notice) but a syringe-full would take noticeable time to diffuse and noticeable gradient while doing so I'd assume. DMacks (talk) 00:11, 11 September 2008 (UTC)

You can give yourself an idea of how much your body prefers salt water by first pouring pure water up your nose, and then pouring salt water. The latter is *much* more comfortable. See neti. --Sean 02:27, 11 September 2008 (UTC)

...which link eventually leads you to nasal irrigation.--Shantavira|^{feed me} 06:33, 11 September 2008 (UTC)

For reference, a saline solution is 0.9% w/v NaCl. See saline (medicine). --Russoc4 (talk) 02:42, 11 September 2008 (UTC)

Well, does the same go for tap water, because clorine is, uh, poisonous, and floride causes retardation? ~AH1^(TCU) 00:03, 13 September 2008 (UTC)

Earwax

Is it true that people in olden times chewed their food more with a sideways movement and then didn't get earwax building up problems/ —Preceding unsigned comment added by 79.76.128.237 (talk) 19:36, 10 September 2008 (UTC)

Uh, no. If your earwax is related to how you are chewing your food, you're probably doing something wrong. --98.217.8.46 (talk) 19:46, 10 September 2008 (UTC)

I doubt it - where did you hear that? --Tango (talk) 19:58, 10 September 2008 (UTC)

From this article: "As mentioned above, movement of the jaw helps the ears' natural cleaning process, so chewing gum and talking can both help." -hydnjo talk 20:12, 10 September 2008 (UTC)

we ha? Chewin and talkin at the same time pardner? Thats mighty advanced for us country folk. —Preceding unsigned comment added by BellyGrease (talk • contribs) 22:44, 10 September 2008 (UTC)

Nah, just a bit of multitasking is all. Now walkin' and chewin' that's tough. -hydnjo talk 10:57, 11 September 2008 (UTC)

Chewing anti-nicotine gum for a prolonged period caused me to lose dentine. Bad news. Kittybrewster ☎ 03:24, 11 September 2008 (UTC)

Whose bright idea was it to put antimatter in chewing-gum? —Tamfang (talk) 16:50, 14 September 2008 (UTC)

Women and How They Think

I'm not trying to be rude in anyway, so please dont take this the wrong way... Why do so many women not have a mind of their own? They'll date a guy or get with a guy that their friends think is good looking. They'll leave a guy they are interested in only because their friends do not like the guy (usually the fat friend that cant get guys). They dont live for themselves, they live for other people. Not all of them, but many of them. Why is this? I don't know any guys that are like this —Preceding unsigned comment added by 75.82.33.31 (talk) 21:44, 10 September 2008 (UTC)

I don't know women that are like that either - maybe you just hang out with the wrong crowd. --Tango (talk) 22:42, 10 September 2008 (UTC)

A lot of them also act like Carrie Bradshaw and do not realise that she is a fictional character played by an actress. —Preceding unsigned comment added by 78.149.104.222 (talk) 23:29, 10 September 2008 (UTC)

Independent, intelligent women pay a price in modern US society. Most men will not put up with it and make such clear in their actions if not always their words. As a result the vast majority of women are socialized into being quiet, submissive, non-threatening. I find it pretty disgusting (and damning of this so-called "free" society). My wife is independent and intelligent and has had to put up with a lot of crap from men over the years. --98.217.8.46 (talk) 23:59, 10 September 2008 (UTC)

The OP is talking about women being submissive to their (presumably female) friends, not to men. If women in the US are quiet, submissive and non-threatening, then I think I should probably move there - the women in the UK are far from it! --Tango (talk) 00:05, 11 September 2008 (UTC)

Men actually do the same thing, in their own way. In certain male-only social circles, it can be seen as unmanly and disrespectful to put one's wife or girlfriend (especially a recent one) before one's buddies in terms of social contact and free time allocation. It's the whole (to be blunt, 'cause this is what's said) 'Hos come and go but your bredren are forever'/'Bros before hos' thing... --Kurt Shaped Box (talk) 00:19, 11 September 2008 (UTC)

I've actually noticed the opposite in quite a few women I know or know of. The amount of crap they're prepared to put up with from guys who are obviously dyed-in-the-wool dirtbags who'll never change astounds me sometimes. Occasionally, when all the cheating/excessive drinking/laziness/disappearing for days on end with no explanation/spending her money or pawning her jewellery without asking becomes too much for her, she'll sling him out on his arse - but it seems like nine times out of ten, she'll take him back after a few days, only for nothing to change at all. I don't know of many (any?) men who'd accept that sort of behaviour from their girlfriends or wives. --Kurt Shaped Box (talk) 00:13, 11 September 2008 (UTC)

I was mostly talking about girls that are 15-25, I know they become more mature and make better decisions as they "grow up."

Well then, you solved your problem yourself, just wait some years or try to get in touch with older women. --Ayacop (talk) 07:28, 11 September 2008 (UTC)

Social contacts are important to both men and women. Also, if other people find another person attractive for whatever reason, this tends to increase the perceived 'value' of this other person, and it doesn't matter whether we're talking about males or females. There is always a degree of competition involved in these sort of things, and for better or worse, someone is far more likely to persue a person other people find attractive and for that matter, find the other person attractive. Finally, I don't see any reason to presume these people aren't living for themselves. Their friends are obviously going to be important to them... Why should this man, who doesn't get along with their long term friends be more important to them then their long term friends? Of course it could be the friends at fault, but people are apt to take the side of the person they have known for longer and often miss some of the flaws in the people they know well. Besides that, if the man they're dating is talking about or thinking about "the fat friend that cant get guys" I would say it is actually the man who is at fault, and good on the girl for dumping that jerk. It's likely to be not in their interest to date such a jerk. To put it a different way, if the girl is happy with her life and friends, how can you say they are not living for themselves just because they choose to reject those who don't fit in with their existing life? Of course, as life priorities change, the importance of friends may change and also an increasing priority for finding a stable long term partner (as opposed to simply one that looks good to other people) but I don't think it's that simple. The people they are dating also change/mature and perhaps are less likely to think about "the fat friend that cant get guys" and also, the person herself is less likely to even be interested in such a guy in the first place. In other words, both parties are maturing and changing, you can't just put it down to one. P.S. As others have said, most of this holds true in some way for men as well. Most men actually do care a lot about what other people think of other any girl their interested and are far more likely to pursue someone perceived as hot then someone who is not... And a lot of men are not going to be involved for very long with someone who does not get along with their friends (the may perhaps keep the relationship for a bit longer then would most females if they're at least having sex). Perhaps the biggest difference is that I suspect, for a variety of reasons, a man is far more likely to not get along with a woman's friends then a woman is with the man's friends. Nil Einne (talk) 17:20, 11 September 2008 (UTC)

Telephone

I remember using a telephone which had a handle one cranked in order to contact the (always a woman at the) local exchange. What was it called? Kittybrewster ☎ 23:06, 10 September 2008 (UTC)

A telephone with a hand-crank

I don't see a specific name for a telephone with a signaling crank, though the contemporary separate-transmitter-and-receiver design was known as a "candlestick". — Lomn 23:28, 10 September 2008 (UTC)

A search on Google indicates the present term is "hand crank wall telephone." In the days when they were in common use, they were probably just calld a "wall phone." In an 1899 book on telephones "American Telephone Practice" by Miller, a drawing of a wall phone with a crank is just titled "Complete telephone instrument" while the candlestick phone illustration is labelled "Desk telephone set."Edison (talk) 03:24, 11 September 2008 (UTC)

You're terrific. Thank you. Kittybrewster ☎ 03:30, 11 September 2008 (UTC)

A a child when I heard on tv cop shows about someone receiving "crank telephone calls," I supposed that they must have been made from one of these old instruments. Edison (talk) 18:43, 11 September 2008 (UTC)

I don't know the etymology, but crank call is used as another name for prank calls. -- MacAddct  1984 ^{(talk &#149; contribs)} 05:54, 12 September 2008 (UTC)

I'm more inclined to the belief that rather than the instrument, it is the caller being referred to: crank (Old English, cranc) ...an eccentric person...; cranky ...full of whims, cross. Hey, there's even a picture of me in the dictionary! :)Franamax (talk) 09:04, 12 September 2008 (UTC)

My reasoning sprung from my grandparents having phones which hung on the wall and had a crany, and their being frequently cranky. Edison (talk) 01:10, 13 September 2008 (UTC)

Magnifier

Why magnification related to recpirocal of lens diam? —Preceding unsigned comment added by 79.76.128.237 (talk) 23:21, 10 September 2008 (UTC)

It will be related to the curvature of the surface of the lens. A small lens can curve at a much faster rate. Graeme Bartlett (talk) 02:57, 11 September 2008 (UTC)

Melting Some Silver

Ok, Wikipedia, here we go. The chemistry class (highschool level) I am aiding for recently did the "Cu wire in silver nitrate solution makes crystals of silver and Cu solution" experiment. The teacher then had an idea to scrape the silver off of the copper wire and melt it somehow. We scraped it off and we have this pile of nitrate soaked silver to work with. We are both wondering whether a methane flame will be enough to get a crucible up to 1234 K or so to melt the stuff. Here's how I'd do it, gathered from some web surfing: 1. Get more silver from the nitrate solution 2. Dry lump of stuff in the crucible first 3. Get it out of the crucible and melt some borax in the crucible (to give the silver a slippery surface to slide around on so that we can pour it out easily? a good idea?) 4.Put the silver back in the (cooled) ceramic crucible, add flux (I read this is good to have to prevent dissolved gas in the melted metal...what is it?) and but the spurs to it.

Anybody have corrections/ improvements on my procedure?72.219.139.201 (talk)

• http://www.visi.com/~darus/foundry/ (Whoa, he talks about newsgroups!)
• http://www.visi.com/~darus/foundry2/
• http://home.c2i.net/metaphor/mvpage.html

DMacks (talk) 00:31, 11 September 2008 (UTC)

Here's some good ideas! My try will be on a smaller scale than that, but the idea of stoking a flame with the blower helps me out...hmm I don't think it would help a methane flame but maybe some mini-charcoal action is due.72.219.139.201 (talk) 05:01, 11 September 2008 (UTC)

Feline parasite follow-up

So I managed to grab one of the buggers. Any ideas? seems pretty flea-like to me. This one was actually a little larger than the rest of them, ~3mm. Sorry for the poor quality, I don't have a good macro lens and I stuck this guy between packaging tape.

Yeah, that's a cat flea. Nasty things. Check with the vet about giving a kitten the anti-flea stuff, but if he or she is cool with it, really, the Advantage/Frontline stuff is super easy (you put a little squirt of it behind their neck and pow! no fleas for a month). --98.217.8.46 (talk) 00:01, 11 September 2008 (UTC)

I'm told you should avoid touching the cat for a day after dosing. —Tamfang (talk) 17:01, 14 September 2008 (UTC)

salt grain physics.

When I was a child , I wondered what would happen If a grain of salt had all of its atoms pushed together so that they all touched.

Naturally there was no internet/physics books in the house/or an expert who could answer this at the time so I never found out.... —Preceding unsigned comment added by 78.149.104.222 (talk) 23:54, 10 September 2008 (UTC)

"Touched" doesn't really make sense, atoms are mostly empty space so there isn't much to touch. You may, however, be interested in degeneracy pressure. --Tango (talk) 00:01, 11 September 2008 (UTC)

Under extreme pressure the molecular bonds such as those in a salt crystal breaks. The bonds between electrons and the nucleus in atoms may also break and you may get matter similar to what a Neutron Star is composed of. It may become a superfluid but we're not really sure because we can't create these immense pressures in a lab. EverGreg (talk) 09:29, 11 September 2008 (UTC)

Tangentially, this reminds me of something Sir James Jeans said: "Put three grains of sand inside a vast cathedral, and the cathedral will be more closely packed with sand than space is with stars." --- OtherDave (talk) 15:46, 11 September 2008 (UTC)

This does not apply to the center of some globular star clusters or even of our galaxy. --Ayacop (talk) 15:59, 11 September 2008 (UTC)

Are you sure about that? The back of the envelope calculations I just did show the cathedral would need to be several square kilometres in size to have the same density as the central parsec of our galaxy. --Tango (talk) 18:28, 11 September 2008 (UTC)

I wasn't the one who said it; Jeans was. He didn't specify which chunk of space. And I did say it was a tangent. --- OtherDave (talk) 10:34, 12 September 2008 (UTC)

(from op)

So assuming we only have the mass of a salt grain and we pushed the nuclei together [somehow :) ] (overcoming the strong force) would we get a mini black hole or would it flash out as an energy burst ...what would happen? —Preceding unsigned comment added by 84.13.83.29 (talk) 19:45, 11 September 2008 (UTC)

If you overcome the force holding the electrons apart, you get something similar to a neutron star. If you carry on and force the nuclei together it will eventually collapse into a black hole which would very rapidly evaporate via hawking radiation. --Tango (talk) 22:31, 11 September 2008 (UTC)