Wikipedia:Reference desk/Archives/Science/2012 October 31

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October 31

Where do those fires in NYC come from?

If they had no electricity, and lighting protection is passive, how could that happen? Comploose (talk) 00:35, 31 October 2012 (UTC)

Broken natural gas lines seem a likely culprit. It doesn't take much to set one of those off. Also, some of the fires seem to be caused by one building catching fire, and passing the fire on to others. Densely-packed cities suffer from such a chain reaction as a constant threat. --Jayron32 00:40, 31 October 2012 (UTC)

Some are caused by downing of overhead electrical power distribution wires ... the "no electricity" follows from the downed wires, rather than precedes. --Tagishsimon (talk) 02:05, 31 October 2012 (UTC)

Also, people who are wet, cold, and in the dark and whose heat and electricity are out tend to light fires for light and to keep warm (fireplaces, lanterns, candles, etc.), and sometimes those fires get away from them. StuRat (talk) 02:14, 31 October 2012 (UTC)

Why wasn't the power cut before the storm made landfall? Count Iblis (talk) 02:40, 31 October 2012 (UTC)

Because lotsa people object to that sort of behaviour - it's not a binary thing.

Also, as StuRat pointed out, even if people are not wet, the move from electric lighting, or from controlled electric or gas heating to largely uncontrolled fires of various sorts, produces far more out-of-control fires per person. Mix that with tens of millions and with darkness, and you get what you get. --Demiurge1000 (talk) 02:44, 31 October 2012 (UTC)

Cutting power preemptively would probably have done more harm than good -- it would have hampered communications and the initial response (due to darkness), and also as Demiurge pointed out, there would be more fires from people using open flames for lighting and heating than from downed power lines. FWIW 24.23.196.85 (talk) 05:04, 31 October 2012 (UTC)

I agree that cutting power without notice is bad, but if scheduled ahead of time and if everyone was notified, then this might encourage people to evacuate those zones, since they don't want to be in an unheated, dark home. StuRat (talk) 05:12, 31 October 2012 (UTC)

I don't think any power company wants the bad press that would come from news reports, "Power Company Turns Off New York, Leaves Citizens in the Dark During Crisis." A failure can at least be blamed on nature. — The Hand That Feeds You:^Bite 20:49, 31 October 2012 (UTC)

I would expect the order to come from the government, so they would get the blame or praise, not the power company. StuRat (talk) 22:17, 31 October 2012 (UTC)

And then hospitals and other high-priority services would have to switch to emergency generators earlier. Completely cutting off power would also put people and facilities that may not have lost power in the dark. People without generators would lose access to TV reports giving last-minute updates on the situation sooner. 209.131.76.183 (talk) 12:12, 1 November 2012 (UTC)

Candles are a common cause of house fires. See this or this, or topically, this advice. Zoonoses (talk) 06:46, 31 October 2012 (UTC)

The idea of cutting the power before a storm hits so you avoid downed live power lines is a bit analogous to the hairbrained idea that some have proposed of turning off cellular service in a disaster. The "solution" is way worse than the problem in the first place. Shadowjams (talk) 21:09, 31 October 2012 (UTC)

They cut power for this reason in Lower Manhattan. The fires in the outerboroughs have mainly been due to exploding transformers--I can't see them but my friend in Brooklyn said she was watching the explosions. μηδείς (talk) 22:47, 31 October 2012 (UTC)

My friends in the upper west side are very glad they didn't arbitrarily cut power. And for them "working from home" doesn't mean not doing anything. Shadowjams (talk) 08:53, 1 November 2012 (UTC)

There was a news report last night of someone whose house burned down because of power being restored. I forget now whether it ignited leaked gas in the home, or what. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:39, 1 November 2012 (UTC)

Science Olympiad

I'm doing Science Olympiad and let say my handout packet tells me that I should know the anatomy of kidney. Is that mean I have to know all structures that made up of the kidney and their functions? And of course the function of the kidney. Thanks!184.97.240.247 (talk) 02:01, 31 October 2012 (UTC)

Yup. You should be aiming to understand & explain the structure, and how the structure relates to the functions. --Tagishsimon (talk) 02:09, 31 October 2012 (UTC)

And what do they mean by physiology of something, example: physiology glial, physiology of neuron. So what exactly do I have to know about it if I want to know about its physiology?184.97.240.247 (talk) 02:31, 31 October 2012 (UTC)

I infer from what you've said about it that you might want to review the organ structures/tissues, how they relate to organ function, what major processes occur there, and how they interact. In the case of the kidney, you could trace the flow of blood (through the afferent arterioles, etc), know the major structures along the path (e.g. macula densa), and how they regulate the production of urine (and how urine varies depending on blood pressure, blood flow, etc) and the production of hormones that act elsewhere in the body. It's a huge topic really, so you might want to start with the big things and work down to details. -- Scray (talk) 02:55, 31 October 2012 (UTC)

Balky burner

I've been meaning to ask about this for some time: One of the burners in my kitchen range (the most powerful one, in case you need to know) occasionally takes several attempts to ignite; however, if while turning the knob I say "Light up, you son of a b**ch", it always ignites without fail. I believe this has to do with the time it takes to attain the proper fuel:air ratio; is this correct? 24.23.196.85 (talk) 06:19, 31 October 2012 (UTC)

Probably, but there is also the possibility you have magical powers. They (talk) 07:07, 31 October 2012 (UTC)

Now there's a cursory answer. Clarityfiend (talk) 07:42, 31 October 2012 (UTC)

I have several crappy burners myself. If I leave it up to the pilot light I will end up with a room full of gas followed by singed eyebrows. Instead, I use a fireplace lighter to light them immediately. StuRat (talk) 07:45, 31 October 2012 (UTC)

There's no way to know without examining it. Does it always start the first time, just with a delay? Or do you have to turn it on and off multiple times? My purely off-the-cuff guess would actually be that your igniter needs replaced. — The Hand That Feeds You:^Bite 21:02, 31 October 2012 (UTC)

This discussion reminded me that for years I've been wondering why so many automatic lighting gas devices become non-automatic so early in their lives? It seems to be one area where society simply accepts crappy technology. HiLo48 (talk) 22:49, 31 October 2012 (UTC)

Well, the typical problem is that we can't tell how long the product will last when we make the purchase decision. For something like this, which we expect to last for decades, we'd need to wait decades to evaluate how long they really last, and, of course, by then all new models will be offered. So, we can't make an informed choice, and the manufacturers, knowing this, have little incentive to provide a quality product.

Once broken, if all it needs is a fireplace lighter to start your burners, there's little incentive to pay to have it repaired or replaced, especially knowing that the same logic will apply to the repaired or replaced item, and therefore it will soon fail, too.

A way to change the incentive structure is to require all products to carry lifetime warranties, where they have to fix it for free. This would get them to offer quality products, but, on the other hand, the prices would also skyrocket. StuRat (talk) 00:21, 1 November 2012 (UTC)

The OP said he ONE of his burners (the large one) is difficult to light. So, presumably the other burners light easily. This suggests it is not the igniter - the hand-held ones tend to work or fail completely. The built in eletric ignitors I have no experience of, but seeing the size of the spark in shop demonstrations, it is difficult to believe they would be iffy. A key question is, is the burner difficult because it is the largest, or because it is the one he uses the most or the least frequently? If it is difficult becasue it is the largest, I wonder if the OP is trying to light it with a match. Otherwise, it could be a problem with dirt, or with corrosion or wear in the jet(s). Town gas can vary - the exact mix of various gasses varies depending one where the gas company buys its' bulk supplies from, where in its life cycle the supplier's underground source is, etc. Occaisonally, it can vary enough that the jet size needs to change - and it is the largest burner where you notice difficulty in lighting first. This happened to us a few years ago. The gas company ran adverts in the newspapers, and sent brochures to consumers notifying them that a change in the bulk supply will change the burning characteristics slightly - they said thaat they believed that almost all customers would not notice the change, but if you do, call them and they'll pay for jet replacement. They also published a list of gas hotwater system brands and models (mostly ones so old they were unlikely to be still in service) that required inspection before the change. Wickwack 120.145.191.8 (talk) 01:43, 1 November 2012 (UTC)

Note that a significant portion of gas stoves, in the US at least, use pilot lights. So, we should ask the OP if they have a pilot light or electric ignition. StuRat (talk) 01:49, 1 November 2012 (UTC)

Mine has electrical ignition, and the spark actually works just fine every time; however, the gas does not always ignite from the spark (but does so unfailingly if I pronounce the incantation while lighting the burner). So the problem can't be with the igniter. 24.23.196.85 (talk) 05:34, 1 November 2012 (UTC)

I think you're right that it hasn't reached the right gas/air mix when it first sparks. So, it may be the timing of the spark which is off. I can think of one long-shot for why you standing there might make a difference: Your body weight may deform the floor just enough to contract or expand a pinched off gas line to increase or decrease gas pressure slightly, thus changing when it reaches the ideal gas/air mix. However, I really don't think that's the case (lucky for you, because that would be dangerous), I blame confirmation bias instead. StuRat (talk) 08:27, 1 November 2012 (UTC)

I think the reason why my saying the incantation makes a difference is that it causes me to turn the knob more slowly, delaying the spark until the right fuel/air ratio is reached. 24.23.196.85 (talk) 22:10, 1 November 2012 (UTC)

Perhaps you should pray to Vulcan ? StuRat (talk) 03:39, 2 November 2012 (UTC)

Unless it's a very short prayer, this might delay the spark for too long... 24.23.196.85 (talk) 05:15, 2 November 2012 (UTC)

Looking for the right word

If you have a big cloud of Hydrogen, it has a certain amount of gravitational potential energy. It also has another kind of potential energy, which is what I am looking for the word for. If all that Hydrogen were to collapse into a star, and fuse completely (i.e. to helium, carbon, etc) is there a word for all that energy? I realize that it is mass turning to energy, but since all the mass does not turn to energy, is there a word for the part that does? Tdjewell (talk) 11:50, 31 October 2012 (UTC)

Relativistic mass is "the sum total quantity of energy in a body or system (divided by c2)." 209.131.76.183 (talk) 12:36, 31 October 2012 (UTC)

it's called Binding energy. Dauto (talk) 15:38, 31 October 2012 (UTC)

That lead me to Nuclear binding energy, which is exactly what I was looking for. I'd mark this Resolved, but I do not know how. Tdjewell (talk) 15:47, 31 October 2012 (UTC)

Potential energy isn't "energy that you can potentially extract". It has a specific technical meaning that doesn't really apply here. I think there's no term for the energy you can extract through stellar fusion. The nuclear binding energy is negative, or zero in the case of hydrogen-1, and though it does decrease in fusion (to a larger negative value), it seems misleading to say that the star's energy comes from that. Ultimately I suppose it comes from the strong force binding energy (or perhaps from quark kinetic energy, which also contributes significantly to the nucleon mass). -- BenRG (talk) 16:22, 31 October 2012 (UTC)

Nuclear binding energy and gravitational potential energy are both negative, for the same reason: the only natural reference level is separation to infinity, where the energy is highest. —Tamfang (talk) 18:27, 31 October 2012 (UTC)

Gravity is a special case that nobody understands, but electromagnetic potential energy is really energy of the field, ∫ (E² + B²), which is always nonnegative. -- BenRG (talk) 20:24, 1 November 2012 (UTC)

I just noticed that the article says that nuclear binding energy is always positive, but that's just because they're using the opposite sign convention. If energy is released in fusion, the total nuclear binding energy goes down in my convention, up in the article's. -- BenRG (talk) 16:25, 31 October 2012 (UTC)

Resolved

Are we trying to contact alien civilizations?

I was reading this article, Scientists suggest we might be overlooking alien communications?, and it talks about SETI actively listening for alien signals. But it made me wonder if we're also sending any communications to alien civilizations? I know that the Voyager spacecraft had golden records and that the Arecibo message was sent for 3 minutes several decades ago. But are there/were there any active attempts to send signals to alien civilizations? It seems to me that the answer to Fermi's Paradox is that everyone is listening, and no one is talking. A Quest For Knowledge (talk) 14:06, 31 October 2012 (UTC)

See Active SETI.--Shantavira|^{feed me} 14:34, 31 October 2012 (UTC)

Some people suggest that telling other civilisations we exist may not be the best idea. Initial interactions between very different cultures in our history have rarely been positive experiences for all participants. HiLo48 (talk) 22:44, 31 October 2012 (UTC)

Hasn't mankind being casually vomiting all manner of electromagnetic garbage into space for over a century anyway? Or have they finally decided that most of that stuff will attenuate to insignificance within a few light years now? --Kurt Shaped Box (talk) 01:13, 1 November 2012 (UTC)

The latter. An omnidirectional broadcast isn't going to make it very far. You need a high-power directional signal aimed at specific targets to have any hope of being heard. StuRat (talk) 01:25, 1 November 2012 (UTC)

that sounds like what a typical earthling would say. unless their technology is so advanced that they can hear it, could that be possible?68.83.98.40 (talk) 01:50, 1 November 2012 (UTC)

Well, if they had a star-sized radio telescope pointed directly at Earth, maybe, but the point is, we could reach thousands of times further with directional broadcasts, regardless of the signal strength required at the other end. StuRat (talk) 01:58, 1 November 2012 (UTC)

StuRat is slightly off target. 68.83.98.40 asked if it is possible a remote being could detect earth manmade stray radiation. The answer is: essentially no. In a vacuum radio waves propagate without attentuation. So if the source is onmidirectional, you just need to build a recieve antenna that subtends the same angle, ie has an effective diameter proportional to distance. So, if you are a ginormous number of lightyears away, you just need to build an antenna the size of a galaxy. It's not for us to say some other intelligent race out there cannot do this. However, in reality, space is not a perfect vacuum. It contains dust, gas, and all manner of things spread out. So, over huge distances, it is like headlights in a dust cloud - there is attenuation wherethe electromagnetic energy is converted into local heat in the dust/gas/etc clouds. At ginormous distances, then, even a galazy sized antenna is not going to pick up anything, as man's stay radiation will have been attenuated below thermal noise. Attempts at SETI and METI have concentrated on certain window frequencies that penetrate space the best.

I do wonder that maybe some METI has inadvertently used such window frequencies that happen to be on some intergalactic distress channel. Just like when I was a schoolboy, and we experimented with crude homemade radio transmitters, inadvertently on an emergency channel, and got a visit from officials who said "do that again, and you'll be prosecuted, meanwhile we are confiscating your transmitter.", we might eventually get visited by some sort of intergalatic police enforcer who has to decide whether to tell us "what the heck do you think you are doing?" or, stop it by sending us back to the stone age.

I've read the justification for METI paper, and I'm not convinced.

Wickwack 60.228.253.243 (talk) 04:01, 1 November 2012 (UTC)

Not sure what of mine was "slightly off target", we seem to have said the same thing. Also, I take it "man's stay radiation" is supposed to be "stray radiation" ? StuRat (talk) 09:52, 1 November 2012 (UTC)

The discussion from KurtShapedBox's post on was about aliens picking up our stray radiation, "vomitting all manner". While some of this "vomit" was and is done with directional antennae, for this purpose the directionality was/is not great, is from multiple sites, and is thus from the alien's point of view not focussed. You were on about using directional antennae which said antenna would need to be very highly directional to signal to aliens, as you said, and also pointed precisely at said aliens). That's a different thing. Eavesdropping versus sending. Wickwack 120.145.198.246 (talk) 11:23, 1 November 2012 (UTC)

• Arguably the Nazca lines are an ongoing effort to communicate with alien civilizations, provided they have very good telescopes. Depending on how far any viewers might be from us, our current efforts might be of comparable seriousness and utility. Wnt (talk) 12:57, 1 November 2012 (UTC)

Conversely, at the space-time separation currently observable from the vicinity of Earth, the current attempts of our nearest intelligent neighbours might be actually or figuratively of comparable efficacy. (Briefly put: Aliens may be at least as bad at this stuff as we are or ever were.) AlexTiefling (talk) 13:37, 1 November 2012 (UTC)

We aren't sure about the purpose of the Nazca lines, but it is extremely unlikely that they were made in an effort to contact aliens civilizations. It is much more likely that they have a religious purpose. They (talk) 11:25, 4 November 2012 (UTC)

Us sending out a powerful beam with a greeting to unknown aliens somewhere in the galaxy might result in a reply and eventually harmonious and informative discourse beamed back and forth. Or it might result in them sending a military force to conquer or exterminate us. It could work out as badly as if Native Americans in the year 1000 AD had built a ginormous outrigger canoe and sent it eastward propelled by trade representatives across the Atlantic with greetings for any civilizations they happened upon, such as the English and the Spanish, with samples of the mineral and plant wealth ripe for conquest in North America. Edison (talk) 21:43, 1 November 2012 (UTC)

Gork: "Darn it, the signal from the 3rd planet in that solar system is interfering with my stories again, and just when Graxon was about to discover his wife was nibbling on somebody else's tentacles ! That does it, I'm firing a disintegration ray to eliminate that bothersome planet, so I can get back to my stories in peace." StuRat (talk) 03:37, 2 November 2012 (UTC)

See Blonde Bombshell (novel). Gandalf61 (talk) 15:58, 2 November 2012 (UTC)

Vitamins and mood

Can you get high on vitamins? They indeed can alter your mood if you are getting too little of them, but is the other way round possible? OsmanRF34 (talk) 21:05, 31 October 2012 (UTC)

You can get delirium as a result of massively overdosing on vitamin A, but that's the only way I know of. Looie496 (talk) 21:28, 31 October 2012 (UTC)

You can feel a lot better after a vitamin shot after a period of deficiency. I have had to get shots due to a chronic condition, now largely ameliorated, that often caused me to have B deficiencies. I felt a whole lot better the next day--but not "high". μηδείς (talk) 22:51, 31 October 2012 (UTC)

I think you misread the Q. That vitamins can help your mood, if you have a deficiency, was a given. StuRat (talk) 00:15, 1 November 2012 (UTC)

No, that's called giving a positive answer to a misguided question. I could just have as easily said no, but didn't find that productive. I also love tuna sushi. Argghll. μηδείς (talk) 02:48, 1 November 2012 (UTC)

I get "high" when I eat high sushi grade tuna. It's like a body rush. 68.83.98.40 (talk) 01:39, 1 November 2012 (UTC)

I remember that, when sushi was still a relative novelty. And hamachi made us randy — I'd like to experience that again! —Tamfang (talk) 19:01, 2 November 2012 (UTC)

some say its tryptophan but I don't get tired I get energizedGeeBIGS (talk) 02:04, 1 November 2012 (UTC)

Can Vitamin A delirium make you see things in the dark? —Tamfang (talk) 19:01, 2 November 2012 (UTC)