Wikipedia:Reference desk/Archives/Science/2007 October 4

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October 4

How come cigarrettes don't have nutrition facts?

--Mostargue 01:43, 4 October 2007 (UTC)

Because you're not supposed to eat them? Because they have no nutritional value? Because there is no legislation requiring it? - Nunh-huh 01:46, 4 October 2007 (UTC)

Yeh, I think you have to ingest something for it to have nutritional value? HYENASTE 01:52, 4 October 2007 (UTC)

For the Language Desk I suppose but why does "how come" translate to "why" (or the other way around)? - hydnjo talk 02:01, 4 October 2007 (UTC)

Supposedly, as a locution for "how comes it that..." or "how did it come about that..." The Random House Dictionary gives a list of similar phrases in noted works: ""How comes it then that he is prince of devils?" (Marlowe, Doctor Faustus); "How comes it that they travel?" (Shakespeare, Hamlet); "How comes it thus?" (Milton, Paradise Lost); "How comes any particular thing to be of this or that sort?" (John Locke, An Essay Concerning Human Understanding); "How comes it to be any concern of yours?" (Fielding, Tom Jones); "How comes this about; there must be some mistake" (Jane Austen, Mansfield Park); "How comes it that we whalemen of America now outnumber all the rest of the banded whalemen in the world?" (Melville, Moby-Dick); and "Then if it's so precious how comes it to be cheap?" (Henry James, The Golden Bowl)." -Nunh-huh 02:10, 4 October 2007 (UTC)

Holy cow! Thanks ;-) - hydnjo talk 02:23, 4 October 2007 (UTC)

Thanks ... --Kushal^{Click me!} write to me 03:15, 4 October 2007 (UTC)

What about chewing tobacco then?--Mostargue 05:27, 4 October 2007 (UTC)

The same answer would hold -- not ingested / not required by legislation. — Lomn 12:58, 4 October 2007 (UTC)

It often is ingested; but not normally in quantities that would have any significant effect on your nutrition. You don't usually have nutrition labeling on cayenne pepper, either, and that clearly is ingested by many people. Gene Nygaard 13:10, 4 October 2007 (UTC)

The short answer is, 'because they're not required to'. Depending on your jurisdiction, different products will fall under different legislation and have different labeling requirements. Beer, wine, and liquor; vitamins, over-the-counter medications, and prescription drugs; cigarettes, cigars, and chewing tobacco—these are all things that you put in your mouth, but in most places they tend not to carry nutritional information on their labels. These products all are regulated in one way or another, though, and all will carry some sort of specific information detailed in whatever local laws are appropriate. TenOfAllTrades(talk) 13:25, 4 October 2007 (UTC)

Thanks. Now here's my science question: if Cigarettes DID have a nutrition facts label, what would it list?--Mostargue 14:06, 4 October 2007 (UTC)

According to TheTruth.com there are over 4000 'ingredients' in tobacco smoke. You're going to need a big label if you are going to list the things that come OUT of a cigarette when it's burned. Listing what goes into one is not so useful since you really don't eat them. Mostly, it's leaves and paper...but that's not the problem - it's what happens to those things when you burn them. SteveBaker 15:48, 4 October 2007 (UTC)

That's 4000 chemical compounds that can be found in tobacco smoke, but ingredient labels list actual ingredients, not the chemical constituents of those ingredients, nor the things they become through combustion. The same source suggests that there are about 600 possible ingredients that are used by at least one cigarette manufacturer, with no indication of how many might be in any one particular cigarette. In any case, it's a bit moot. Cigarettes get warning labels, not nutrition facts labels; there's no nutrition involved, so there can be no meaningful answer to the hypothetical. - Nunh-huh 16:01, 4 October 2007 (UTC)

But I've seen stuff like mouthwash, which clearly shouldn't be ingested, have nutrition facts. Certainly tobacco companies are required to list the ingredients of their product? I'm sure they could fit a small folded into the carton listing all the ingredients. If not, is this a result of the tobacco lobby?--Mostargue 16:06, 4 October 2007 (UTC)

I think you are thinking of an ingredient list: certainly mouthwashes have that. I've never seen mouthwash with a nutritional facts label. for, say, a pizza, the ingredients would be Enriched flour, water, mozzarella cheese, pepperoni, tomato puree, asiago cheese, parmesan cheese, yeast, maltodextrin, Salt, Garlic Basil, etc., but the nutritional label would be more like this: . Cigarettes (or mouthwash) don't have the fat, carbohydrate or protein content that would make such a label meaningful or useful. - Nunh-huh 16:25, 4 October 2007 (UTC)

In the USA, alcohol and cigarettes are not managed by the Food and Drug Administration, so both are exempt from the FDA's nutritional information labeling requirements. (Mouthwash usually has an antibacterial agent, so it is regulated as a drug, not as an alcohol... isn't bureaucracy amazing!) We have an entire Bureau of Alcohol, Tobacco, Firearms and Explosives, a federal agency responsible for regulating these items. In addition, individual states may have further requirements regarding distribution (though this probably does not affect labeling and packaging). Nimur 16:24, 4 October 2007 (UTC)

Lungs vs stomach

In response to previous question:

Would it be possible to gain nutrients from an aerosol or powdered spray vitamin? It would be administered like an inhaler. Or are the lungs unsuitable to distribute nutrition to the body? HYENASTE 01:52, 4 October 2007 (UTC)

You can administer certain drugs (such as insulin) through the lungs, but these are drugs, rather than nutritional substances. This in essence is exploiting the highly vascular lung structure as a drug delivery system. A cigarette is a means of getting a drug, nicotine, into the blood stream. You can't eat with your lungs; unlike the G.I. tract, no digestion occurs there. . - Nunh-huh 02:06, 4 October 2007 (UTC)

I understand, but what is the difference between insulin and, for example, vitamin A? And on a tangent, could you create an insulin cigarette? :P HYENASTE 02:40, 4 October 2007 (UTC)

By "cigarette" do you intend a delivery system that "burns" something to deliver useful insulin as a vapor or gas? - hydnjo talk 02:51, 4 October 2007 (UTC)

No, a cigarette is made of tobacco. Inhaled insulin is delivered as a powder. See this page if you are interested in inhaled insulin. - Nunh-huh 04:12, 4 October 2007 (UTC)

There may not be any digestion in the lungs, but digestion is a means to break down food to get the nutrients out, which go into the blood. Lungs are also designed to get stuff into (and out of) the blood (oxygen and carbondioxide, resp). But other substances can also be absorbed, such as several drugs. One could also ask this the other way around; which gases would the lungs not let through? DirkvdM 06:41, 4 October 2007 (UTC)

The lungs let all gasses through (useful in the delivery of anaesthetic gasses, for example), but the drugs so far alluded to are either solid or liquid; the question to be asked in regard to drug delivery is whether enough of the drug can be administered via this route to have the desired effect. - Nunh-huh 15:15, 4 October 2007 (UTC)

For large molecules (sugar, most proteins, etc) you generally need an active cellular pump to move the molecules into and out of the bloodstream. These are present in the digestive system, but not in the lungs. --Carnildo 22:02, 4 October 2007 (UTC)

When do pipes freeze?

How cold does it need to be to freeze pipes. Specifically, at what temperature will pipes freeze where a water faucet that extends from the outside of the house connects to a drip watering system that primarily lays on or just under the ground.

Thanks! —Preceding unsigned comment added by Prplflwr1 (talk • contribs) 02:30, 4 October 2007 (UTC)

Given enough time (this is important) and if the drip is slow enough (also important) and if the water is reasonably free of minerals (again important), slightly below 0ºC should do it. If the ground/soil is colder than 0ºC then things should freeze up faster but remember that the "drip" or flow rate and the temperature of the flowing water and the length of piping etc. could prevent or encourage freezing. So, we need more data to give you even a ballpark estimate. - hydnjo talk 02:59, 4 October 2007 (UTC)

At my place the hose will freeze up easily if temperature is below -1°C and it lies on top of the ground, but the water supply pipe very rearly freezes, it will have to be below -5° for quite a while to go solid. I have never had temperatures below -10° where I live. Graeme Bartlett 06:42, 4 October 2007 (UTC)

Per Hydnjo, there are a lot of factors to consider. Ordinary tap water will freeze at close enough to 0°C so as to make pretty much no difference. While the pressure in the pipe will depress the freezing point very slightly, it's not going to help appreciably—for a single degree drop in freezing point, one would need to elevate the pressure by about 140 atmospheres.

More important is the flow rate in the pipe and its amount of insulation. In order for water to freeze solid, two things must happen. First, it has to get cooled down to 0°C for the freezing process to start. Then you need to remove additional heat – the latent heat of fusion – to actually convert the liquid water into solid ice. It turns out that this second step actually involves quite a bit more energy than the first step. (The specific heat capacity of water is about 4 joules per gram per degree Celsius; to take a gram of cold tap water from 8°C to 0°C one must extract 32 joules of heat. The latent heat of fusion of water is 334 joules per gram—ten times as much.)

So the question becomes, for the flow rate, level of insulation, length of pipe run, and exterior temperature, will a gram of water be able to shed 300 or so joules between the point where it leaves the insulated home and where it exits the pipe? TenOfAllTrades(talk) 13:05, 4 October 2007 (UTC)

Beyond what TenOfAllTrades said, there's also the question of how much heat is getting into the water piping from inside the house. When we had a spate of very, very cold weather, within the house, we deliberately removed some of the thermal insulation that was covering the copper pipe leading to the sill cock/bib cock. This allowed more of the heat from the house to reach the "freezable" part of the pipe, keeping it from freezing. Alternatively, you could wrap the pipe in electric heating tape; these tapes often come with an automatic thermostat so they only switch on as the pipe approaches freezing temperature. All in all, it's a fine dance between wasting energy and frozen pipes!

Atlant 13:23, 4 October 2007 (UTC)

There are way too many variables. In Texas, when the weather gets below freezing, it only ever does it for a couple of days each year. So at the depth below ground of the water main coming into the house, it's still well above freezing - so relatively warm water is feeding the drip and keeping the pipe warm. It's unlikely ever to freeze. However, if you're in a part of the world where there is snow/ice on the ground for many months then the water main itself is only just above freezing (maybe it even runs through permafrost!) - so you are dripping very nearly freezing water - and your outside pipes could very easily freeze. Another variable to consider is where the faucet is plumbed into the house. At our home in England (where it does get cold enough for long enough), we have one outside faucet on the side of the (unheated) garage and another coming out of the wall next to the downstairs bathroom. The former freezes up alarmingly often (and even split once) because the water comes out of the cold ground, through the cold garage and then outside. The outlet next to the bathroom never froze because the air inside the bathroom is nice and toasty - and the pipe T's off of the bathroom plumbing and then heats through the wall to the garden. Only a few inches of pipe are exposed to the cold - so it never freezes even without letting the faucet drip. So it's not enough to say what outside temperature makes things freeze. You need to know the deep underground temperature, the amount of pipe that runs through heated parts of the building, you need to know for how long the outside temperature is that cold...insulation...just too many things. SteveBaker 15:40, 4 October 2007 (UTC)

Is it liquid mercury?

A liquid which produces a convex surface in a graduate cylinder. —Preceding unsigned comment added by Popbet (talk • contribs) 02:46, 4 October 2007 (UTC)

This sounds an awful lot like a homework question. The concavity of a liquid in a graduated cylinder is dependent on the cohesion of the liquid, and its adhesion to the material of the cylinder (with complications that don't matter for your question). From reading those links, you should be able to figure out whether mercury is a candidate. Someguy1221 04:59, 4 October 2007 (UTC)

• (EC) It depends what the cylinder is made of. For glass, mercury will indeed be convex. See meniscus. --Sean 05:01, 4 October 2007 (UTC)

That's what all the books say about mercury, but if you look at a real mercury thermometer, the surface looks flat. Why? Do those not use a glass tube? The article about mercury has an image of a mercury barometer which shows the same. – b_jonas 16:48, 4 October 2007 (UTC)

Thermometers and barometers use very small tubes where the capillary effect is the dominant feature. In other words, the tube is too small for a visible meniscus. Nimur 16:53, 4 October 2007 (UTC)

Ice cubes and the family jewels

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis.

(EC) You should consult a medical professional. If nothing, it will give them a good laugh too. Lanfear's Bane 15:42, 4 October 2007 (UTC)

You know, I'm not sure it's fair to the rest of us Reference Desk Regulars to hide questions like these. We could have at least linked the poor questioner to the Darwin Awards article or made some sort of awful "frozen stiff" joke.

Atlant 13:27, 4 October 2007 (UTC)

That's what edit histories are for :-) SteveBaker 14:35, 4 October 2007 (UTC)

That's pretty lame. Who would look something up if they don't know what it is? And especially if they have to go through that trouble (the history page is of course quite huge here), assuming they know how to do that in the first place. In this case the header might be interesting enough, but that is not normally the case. DirkvdM 18:17, 4 October 2007 (UTC)

Yeah, it wasted 2 minutes of my life to look that up in the history page... --antilived^{T | C | G} 21:05, 4 October 2007 (UTC)

Thank you, Antilived. Personally I can't get up enough enthusiasm to go through all that stuff on the history page.--Eriastrum 22:38, 4 October 2007 (UTC)

LOL that's hilarious --froth^t 23:04, 12 October 2007 (UTC)

Unplugging electronic devices

My router at home doesn't have a power button and, whenever I need a new IP address, I have to unplug it. For some reason I feel suddenly unplugging an electronic device, such as my router, can damage it. On the other hand, there are many computer peripherals which simply don't have a power button, so it mustn't be crucial for the survival of the device. Additionally, what a power button does is to (suddenly) interrupt the flow of electrons into the device, isn't it? So, is it unsafe or not? --Taraborn 13:24, 4 October 2007 (UTC)

Unplug the AC (mains) side of the power brick/wall wart, not the DC connector side. You'll be fine. After all, the router must be designed to survive power failure]s undamaged, right?

Atlant 13:29, 4 October 2007 (UTC)

Could you briefly explain why I should unplug the AC side instead of the DC one, please? Thanks for your answer. --Taraborn 13:51, 4 October 2007 (UTC)

Unplugging the mains side ensures that power goes away monotonically, whereas pulling the DC power connector may lead to a series of brief power interruptions and restorals that might wreak havoc with the electronics of the device. You may even get arcing. Also, if the DC power connector has more than one power rail, who knows what the removal and re-application sequence of the voltages will be? As I said, the device is clearly designed to withstand interruptions of mains power, but it's not nearly so clear that it's designed to withstand (many) cycles of DC power via the DC power connector. But its' your device so you obviously don't have to take my advice ;-).

Atlant 16:34, 4 October 2007 (UTC)

I'd say unplug the DC (almost entirely for convenience' sake, though the paranoid can also take comfort in staying further from mains power). As a practical rule-of-thumb, sudden shutdowns will not break electronic devices. You should avoid sudden shutdowns of data storage devices (USB drives, hard drives, etc) while they're doing stuff to prevent data corruption, but yanking the plug on a router is fine. — Lomn 14:41, 4 October 2007 (UTC)

I can't think of a reason to prefer the AC side. But to answer the original question - with things like this, you only have to worry about unplugging them 'suddenly' if they have data in volatile memory (RAM) that has not been saved out to a more permenant form of storage like a hard disk. For PC's, shutting them down by yanking out the power cord or pushing the OFF switch isn't good for them - but for something like a router that stores things in flash memory, you should be OK to turn it off providing you wait just a few seconds since the last operation. I'm a little concerned that you have to unplug it at all however. Are you doing this so that your computer gets a new IP address when the router comes back up again? Or is it that when you shut down your computer and bring it back up again, the router doesn't give you a new address properly? If it's the latter, then your router is set up incorrectly...which would be a good question for our Computer reference desk. If it's the former...why? SteveBaker 14:41, 4 October 2007 (UTC)

Thanks to all. My reason for needing a new IP address is that one-click hosts impose a download limit for non-premium users. --Taraborn 15:13, 4 October 2007 (UTC)

The flaw in your logic is assuming that the power button does something more than break the power rail circuit. In some sophisticated devices, the power switch may trigger a software or hardware shutdown routine, but most small appliances just power down. In that case, unplugging a cord or pressing a button is technically equivalent. Nimur 16:30, 4 October 2007 (UTC)

I know, I know that my logic isn't the law of gravity, just a general thought for the most common devices. --Taraborn 07:49, 5 October 2007 (UTC)

As a rule, you want to use the power switch if there is one. Among other reasons, any time you make or break a circuit you get an arc. In low-power devices, the arc is a teensy one. Down at the power station, it's a big, nasty, Frankenstein one. A switch is physically and electrically designed to take that. I have to unplug my router once in a while when it gets confused, and I always just yank the DC. But if you're worried about it, put the router on its own little power strip, and use the switch on that. One reason it's better to cut the power at the wall is that the doodads in the pack help soak up whatever spike happens. If you want it more technical, let me know. --Milkbreath 17:50, 4 October 2007 (UTC)

I do not think you should even need to power down your router to get a new IP. There should be a reset button that you can use a paperclip to activate. Alternatively you should also be able to reboot the router or have it release/renew the WAN IP from the router's interface. Try plugging 192.168.1.1 into the adress bar of your web browser (other common router LAN IPs are 192.168.0.1, 192.168.123.254, and 192.168.2.1). If you can access the interface you can get a new IP wothout even getting out of your chair! 161.222.160.8 22:27, 4 October 2007 (UTC)

Pressing the reset button will return the router to factory settings in addition to restarting it, which a lot of people probably don't want to do. Someguy1221 23:28, 4 October 2007 (UTC)

Hmmm... Not for me. I have used it many times. All settings stay the same (ports, DHCP, static vs. dynamic). Come to think of it, on my particualr model I think the only way to restore defaults is through the console. Good point though, reset switch is prob not the best idea unless you know what will happen. 161.222.160.8 00:41, 5 October 2007 (UTC)

I would disagree with Atlant that interrupting the mains by withdrawing the plug would result in a monotonic decay of the output voltage. Any voltage above about 70v a few hundred in air at atmospheric pressure is likely to produce arcing. See Paschen's Law. This will give nothing like a monotonic decease in the output voltage, but a series of surges. I would recommend unplugging at the low voltage or dc section of the power supply.--88.109.121.209 01:36, 5 October 2007 (UTC)

Yeah, but the bulk storage capacitors in the power supply unit will mitigate this; they've already got enough charge in them to ride through at least a half-cycle of the power waveform so introducing small pulses of the (current value of the) power waveform won't affect their charge level much. As I said, one can take my advice or not; it has no impact on me; my networking gear is all powered from a single (common) wall switch so when it needs to be reset (and it does occasionally), I just flip the switch down and back up again.

Atlant 13:27, 5 October 2007 (UTC)

Bear in mind that large electrolytics have quite a high impedance at rf frequencies, so unless there is proper surge protection, these spikes are going to get through your power supply. I surmise that it all depends upon the current one is trying to break, whether there is enough inductance in that circuit to cause arcing, whether that arcing can be supressed by any filtering you have, and whether the residual surges can damage any components. Its not really a simple question. My advice would be; break the circuit at the lowest voltage/current that you can and make sure the switch dosent cause more bouncing than your filters/suppressors can handle.--88.109.121.209 15:12, 5 October 2007 (UTC)

I would love to see this question copied to the Computer reference desk. --Kushal^{Click me!} write to me 02:59, 7 October 2007 (UTC)

Identifying an insect

I don't have a photo, I'm afraid, but it had noticeable orange legs with a browny-orange body, and on the end of the body it had a black patch. It had reasonably long orange antennae and had two points on its 'shoulders' like shoulder blades. Does anyone know what it could be? I'm in the south of England. Thanks. —Preceding unsigned comment added by 84.68.35.79 (talk) 13:28, 4 October 2007 (UTC)

Your description of "shoulder blades" suggests the Shield Bugs, Pentatomoidea. However, I can't after a quick look find one that has orange antennae. Try doing a google image search of these names and see if they are similar. How big was the insect? What was it doing? What kind of environment did you find it? Did it have wings?--Eriastrum 15:47, 4 October 2007 (UTC)

Does it match the pics at shield bug ? StuRat 06:11, 5 October 2007 (UTC)

Peri-synaptic

What does peri-synaptic mean? Lova Falk 14:17, 4 October 2007 (UTC)

Just as "perinatal" means "the time before and after a birth" or "the time around birth", so "perisynaptic" means "the area before and after a synapse" or "the area around a synapse". -- Nunh-huh 15:09, 4 October 2007 (UTC)

Thank you! I didn't know what perinatal meant either. :) Lova Falk 15:31, 4 October 2007 (UTC)

Maybe "periscope" would have been a better explanation...it lets you look all around.....  :) - Nunh-huh 15:53, 4 October 2007 (UTC)

When I think of the meaning of peri-, I always think first of periokoi, but I may be non-typical here. Algebraist 17:20, 4 October 2007 (UTC)

Within this small period of time, several perilous suggestions almost made me perish... Lova Falk 18:31, 4 October 2007 (UTC)

Well then have a look a the Peripatetics walking around. The word gave the now disused french "péripatéticienne" for ... hooker! Keria 21:39, 4 October 2007 (UTC)

You got one out of three. Period does come from Greek peri- "around", but peril comes from Latin periculum "danger", and perish comes from Latin per- "thoroughly, completely", neither of which is related to peri-. —Keenan Pepper 04:47, 5 October 2007 (UTC)

It makes me think of chicken... — Matt Eason ^{(Talk • Contribs)} 23:30, 4 October 2007 (UTC)

about optical microscope

can we start the design of microscope with objective using ZEMAX.If i start like that what happens regarding aberrations.which type of objective i can use to get 100x magnification. —Preceding unsigned comment added by Mahendarkumbham (talk • contribs) 15:13, 4 October 2007 (UTC)

Jack plug

When cutting the wire of a three connector jack plug I can see 3 wires. From the outside it looks like 2 wires running alongside but when i cut them: one in its own plastic insulation and in the second i find a wire wrapped around a smaller third inside a white plastic insulation. Which is left, which right and which is ground? Thank you. Keria 17:34, 4 October 2007 (UTC)

Sorry my mistake it's actually two pairs of wires and the solution is there http://forum.ecoustics.com/bbs/messages/15118/14935.html . Keria 17:48, 4 October 2007 (UTC)

Definition of a Human

What do people think of this definition? An embryo must have both brain and heart cells present (happens three weeks after conception) to be considered a human or must have at least one cell from each organ that a healthy adult cannot live more than a 24 hour period without. I have also heard that a human is composed of three parts: body, soul and spirit. If this is true, is there a way of detecting this and if so would this change the definition of a human to be: have both heart and brain cells present and have a detectable soul/spirit? —Preceding unsigned comment added by Rsdetsch (talk • contribs) 17:38, 4 October 2007 (UTC)

You may define a human however you like for any given argument. Definition of terms is really a matter of choice, not science. As far as detecting a soul, there is no scientific evidence that any detectable item which you might call a soul exists. We do, however, usually have an easily detectable brain. Nimur 17:41, 4 October 2007 (UTC)

One might argue that someone doesn't have a "soul" until well after birth, maybe even back it up with various religious references. As Rsdetsch (actually Nimur) says, there's no empirical evidence of a soul, only religious or non-scientific theories. -- JSBillings 17:46, 4 October 2007 (UTC)

I said that, not Rsdetsch! Nimur 17:48, 4 October 2007 (UTC)

Whoops, sorry. I picked the wrong name out of the earlier wikitext. -- JSBillings 17:51, 4 October 2007 (UTC)

Thanks for your comment(Nimur), but is there an indirect way of detecting a Soul and/or a relational dependence we can associate with its existence. Like a Soul cannot exist without a brain? —Preceding unsigned comment added by Rsdetsch (talk • contribs) 17:49, 4 October 2007 (UTC)

It depends on your definition of Soul. Check out the Science and the soul section, to see some attempts of defining "soul" scientifically. You'll see a later discredited attempt to discover the weight of the soul by measuring the weight of the body before and after death. -- JSBillings 17:55, 4 October 2007 (UTC)

That is an interesting point (JBillings), if one was able to come up with a unique weight of a human soul then one can come up with a necessary (not sufficient) condition of being human e.g. if the embryo weights less than that unique weight it is not a human. —Preceding unsigned comment added by Rsdetsch (talk • contribs) 18:14, 4 October 2007 (UTC)

No - that truly wouldn't help. If you could come up with some bizarro experiment that measured the weight of a soul - I guarantee that you'd be able to do the same experiment on a Chimpanzee - get more or less the same result - then have to fight tooth-and-nail with the religious loonies who claim that "animals don't go to heaven because they don't have souls" - so now you have to label this thing that your experiment showed up with some other name - and now you are no closer to proving the moment of humanity. SteveBaker 18:18, 4 October 2007 (UTC)

Besides, you'd have to prove that souls have constant weight. If not, the weight of a fullgrown one would not help. 69.95.50.15 20:10, 4 October 2007 (UTC)

It doesn't really matter how you make your definition - it's just a word after all. What matters is what you intend to use the definition FOR. If (to take an obvious example) you are talking about the abortion debate - then one bunch of people are going to complain bitterly about your definition because it de-humanises the very young and "permits people to murder them" - and another bunch are going to complain just as much because it implies that the termination of a fetus beyond a certain (fairly early) age is "killing a human" and that would effectively remove "the right to choose". So, by all means, define the word however you like - but don't expect many people to agree with you! There is no "right" definition from a scientific perspective - there is a continuous process from the instant of conception, through birth and into adulthood - and we could pick any one of a bazillion events along the way to label as "the transition to humanity". Personally, I would prefer to use the word 'human' throughout the process - the label says what kind of cells this fetus is made of - as in: "This is a human egg/fetus/baby/child/adult as distinct from a chimpanzee egg/fetus/baby/child/adult." SteveBaker 18:15, 4 October 2007 (UTC)

Well said, SteveBaker. I have to wonder why having a brain, heart or soul matters for the definition of Human. Does having an artificial heart make one less human? What about an artificial brain? One could go as far as defining Human as the common genetic sequences all humans share. I think the OP really was trying to define what makes someone a conscious entity (although the heart is no more important than the lungs when it comes to cognition). -- JSBillings 20:02, 4 October 2007 (UTC)

• Typically these debates focus on "personhood" rather than humanity. My own simple test -- equally unsatisfactory as a universal one, no doubt -- is "if it looks like a person, it is". I could quibble about when that happens, but I'll never be convinced that some "persons" look like this (actual size) ---> • --Sean 20:12, 4 October 2007 (UTC)

Just don't try to use that to advocate abortion. The question isn't about whether or not it's killing something that looks like a person. The question is about whether or not killing a fetus, whether or not it matches any definition of a person, is wrong. — Daniel 23:29, 4 October 2007 (UTC)

I like to look at the implication of a proposed rigorous definition of what is a human. If heart tissue must be present to qualify, then during a heart transplant, the recipient ceases being human for a while once his old hear has been removed and before his new heart in installed. He was human when they began the operation, then he was not human for a while, then he was human again. The notion just doesn't work for me. Edison 02:26, 5 October 2007 (UTC)

We have an article on that effect and several variations (all stem from a continuum fallacy. It's come up on the desk a few times. As I mentioned, you can play whatever games you want with your definitions. Consistency becomes very difficult when you take a large number of scenarios into account. Nimur 03:08, 5 October 2007 (UTC)

The problem is that it's OK (useful, valuable, reasonable) to give a name to some region of a continuum - so to say "This is a fast car" because it can go 200mph is not disputed by anyone and to say "This is a slow car" when it has a top speed of 20mph would not be disputed. The problem comes when you get into the grey area between those two terms. Is a car that can only go 70mph fast or slow? But this doesn't matter so long as you don't use these vague 'partial-continuum' names to force a binary yes/no decision. We don't try to pass laws that say "You aren't allowed to drive fast down this road" - we say "You aren't allowed to drive at more than 40mph down this road".

The same exact problem bedevils the abortion debate. We mostly agree that you shouldn't be allowed to kill a "person" - but almost all of us agree that a single cell is not a "person". If I cut my finger and it bleeds - we don't rush the droplets of blood to the hospital and attempt to keep them alive - yet they are just as 'alive' and 'human' as a newly fertilised human egg cell. So here we have a continuum - yet people are talking about it as if it was not a continuum. This forces some people to have to take an extremist attitude that goes something like "Because we don't argue about whether a two-week premature baby is a person - and we have a continuum from there all the way back to the instant of fertilisation of egg by sperm - then we must declare that one is a full person with all rights that this entails from the moment of fertilisation."...but in reality, that's as dumb as saying "Driving at 200mph is obviously dangerous and should be disallowed - but because there is a continuum between that and 0.001mph, then it follows that all cars must be banned." SteveBaker 14:51, 5 October 2007 (UTC)

I agree the continuum is something a lot of people, particularly religious types tend to miss. Note also that both sperm and (unfertilised) ova are alive before fertilisation. If they weren't alive then fertilisation could not occur. While they may be haploid, they're also human. Also the idea that 'personhood' (whatever that means) begins at fertilisation get's somewhat confused when we consider that with identical twins (or triplets), the same zygote which you say is one person can become two or three people. The reality is trying to define a set beginning to 'life' and 'personhood' just doesn't work IMHO Nil Einne 01:36, 7 October 2007 (UTC)

Yeah there's a continuum, so there's no exact point where it goes from a splattering of cells to a baby, but obviously you can't ignore the change between "I squashed a single cell so what" and 8.9 months later "holy crap that's a baby that happens to be inside a woman".. this is what is struggled over. Just because we can't define exactly when a person acquires said personhood doesn't mean that they don't acquire it.. aborting a fetus 1 day before delivery is essentially identical to birthing it and then killing it, and killing single cells is trivial, but though it make be indeterminate we can't just ignore the space between. My position on abortion is that if people aren't prepared to kill their newborn, but are willing to abort a day before then they're the ones with the nonsensical arbitrary position. Not refuting what you're saying but extending it? --froth^t 03:27, 10 October 2007 (UTC)

In which point this discussion started to be against WP:NOT#FORUM? We can't say, the process was continuum. 200.255.9.38 15:01, 10 October 2007 (UTC)

Moon Rise and Set

I watch the moon quite frequently when out walking my dogs. Although I know there are phases to the moon and how long it takes for that whole cycle to occur. I haven't seen anything that tells how to tell what time the moon will rise and when it will set. Is there a specific way to know that?206.17.145.132 20:32, 4 October 2007 (UTC)beth

Some newspapers print sunrise, sunset, moonrise, and moonset times; otherwise you need to consult an almanac or its equivalent. It obviously depends on your specific location. One that's online is <http://www.skyandtelescope.com/observing/objects/javascript/3305541.html#> - Nunh-huh 21:33, 4 October 2007 (UTC)

A full Moon is opposite the Sun, so it rises when the Sun sets (roughly at the other side of the horizon) and vice versa. A new Moon is at the same side as the Sun, so it rises and sets together with the Sun, at roughly the same spot. You figure out the middle parts. :) (Sorry, a bit tired now, should be going to bed). DirkvdM 18:50, 5 October 2007 (UTC)

Awake again now. See lunar phase. In the first quarter, the Moon is straight overhead at sunset (where it says 6 pm) and then follows the Sun and sets in the west at around midnight (depending on how your timezone differs from solar time). And in the third quarter (when it forms a 'C' in the Northern Hemisphere), it rises at midnight and is overhead when the Sun rises. DirkvdM 08:55, 6 October 2007 (UTC)

Thirst for knowledge and the human condition

Okay, so this is more of a philosophical question than an actual scientific one; but what if one day we reach the limit of miniturisation and computational power and still the technology we have has not unlocked the secrets of the universe and the human condition. What happens next? Are there enough 'clever people' to be able to think our way to the answers we are looking for? Do we simply give up on certain questions? What if locked within our own experience is the inherant inablility to understand even the questions to ask, let alone the answers we find? --russ 22:55, 4 October 2007 (UTC)

You are asking the wrong question. We will never the unlock all the secrets of the universe because we only have 80 years of thinking life. Just look at what it takes to do orignal research nowadays, you need to study for 25 years before you can reach a point where you know the known science.

If we ever reach a point where we need to study 80 years before we can do original research then we have hit our thinking limit and humankind cannot progress further scientificly. 202.168.50.40 23:16, 4 October 2007 (UTC)

Yes, I agree with your perspective, but I meant generally, rather than personally - could one individual not continue another's work until we find the answers we are looking for, much in the same way that that for instance our understanding of 'gravity' continues to develop, even though it takes centuries to build up that knowledge? I am making the assumption that we are able to build upon our understanding, otherwise fields that took Newton and Einsein a lifetime of calculation to grapple with would not have progressed, surely? --russ 23:26, 4 October 2007 (UTC)

John Horgan wrote a book called "The End of Science" and suggested that we are passing out of the golden age of science. My personal view is that there is still a large amount of interesting science to be done, and it seems far to early to put much effort into worrying about "the end of science". --JWSchmidt 02:12, 5 October 2007 (UTC)

It seems to have been a general feature throughout the history of the sciences that as soon as people start making comments about having "discovered nearly everything", "just need to get the constants down to a couple more decimal places and fill in a couple of holes", "solve some minor problems", etc. - that's when someone makes some startling discovery that turns all of our current knowledge on its head. I'd even be willing to guess that we're approaching such a time soon. Confusing Manifestation 04:10, 5 October 2007 (UTC)

What I'm trying to say is that all the easy fruits have already been picked. The fruits of science still left hanging on the tree of knowledge are the really hard ones, ones that needs years of study before you can even begin to try picking them.

But you can't go from this to say that we have picked all the fruits of science. There will always be fruits of science so high up the tree of knowledge that we can never pick them. 202.168.50.40 04:47, 5 October 2007 (UTC)

Science as we know it today is not the right method to unlock the secrets of the universe and the human condition. Lova Falk 09:13, 5 October 2007 (UTC)

People thought we had discovered everything useful in physics in 1905. The only things left were blackbody radiation and the nature of light, but it was thought those things would be solved soon under classical physics. They couldn't be more wrong.--Mostargue 11:20, 5 October 2007 (UTC)

• There's no reason to be sure that we will be *able* to understand everything that we can observe. There's no more evolutionary requirement for us to be able to, say, come up with a grand unification theory than there is for a dog to be able to set the time on a VCR. --Sean 12:34, 5 October 2007 (UTC)

Are we close to knowing everything? The claim that we're close to having learned all that there is to know comes up at least once a century - and every time (so far) it's been proven wrong. To be sure, the rate of new discovery is increasing exponentially - but there are two ways to look at that. One is that at this prodigious rate we'll very soon have discovered everything we're capable of - but the other is that we are opening up lines of new enquiry at an exponential rate too. So I doubt we'll ever know everything - but I'm optimistic that during the last 50 years we've answered a lot of the really big questions to a reasonable degree of accuracy. The very large, the very small and the very old were shut out of our knowledge until quite recently but now we can answer "Where did we come from", "What makes the sun shine", "What is the smallest indivisible object"...many of those things were still completely uncertain even 50 years ago - yet nowadays, even my teenage son has a pretty good shot at giving a good answer.

Are there things that we cannot ever solve? Yes - we know that there are mathematical theorems can be neither proved nor disproved, we know that some measurements are strictly limited in precision, we know that some calculations will take longer than the life of the universe to perform so we cannot calculate an answer, we know that 'sensitive dependence on initial conditions' (chaos theory) puts sharp limits on our ability to do even seemingly easy things like predicting the weather that we once thought we'd have solved within 50 years.

Are there are things we can't ever do because we aren't smart enough?...that's a tough one. Humans have several unique abilities that mitigate the limits of the sizes of our brains. We have computers - it's pretty clear that we can make a computer that's faster than we are and which has a better memory - we're fairly sure that a computer that's generally more intelligent than us is possible (although efforts to actually build one have been frustratingly difficult). But if such a computer existed, it could probably be used to make another computer yet faster and smarter still - and so on to the limits of practical technology. (Let's face it - there is absolutely no way we can design a computer even now without using another computer to do the bulk of the work.) We have writing and speech which lets us communicate ideas so that one person doesn't have to solve a problem alone - we network our brains and our increasing population is making us collectively smarter. We can also spread the work of making a discovery over many generations - breaking problems into sub-problems and sub-sub-problems until we have small enough pieces to be tractable to a single person within their lifetime.

Is there an issue with it taking longer and longer to learn what you need to know to get started on a problem? This is something that we've always solved by specialising. As subjects get too large for one person to fully understand, we split them into specialities. So in the time of Newton, one person could be fairly conversant will all of science and mathematics. Nowadays there are dozens of branches of mathematics and hundreds of sub-specialities within science because even knowing everything there is to know about (say) cosmology is more than one person can handle.

SteveBaker 14:23, 5 October 2007 (UTC)

Dweller's thread of the week. It's an 'out of the box' idea.

Congratulations to all contributing here. This mindbending debate about the depths of our ignorance wins the seventh User:Dweller/Dweller's Ref Desk thread of the week award. Good job. --Dweller 09:17, 8 October 2007 (UTC)

Here's one of those can-of-worms "little details" like blackbody radiation and the nature of light- extraterrestrial life. We tend to ignore it since there's really nothing to be done but wait for technology to advance sufficiently to explore space, but that only sets us up for panic if it actually happens.. think of how much we could learn from the scientific work of a completely different academic universe.. surprising new ideas we would have never considered.. So science is far from reaching its end, but that's assuming that humanity still cares- I tend to see the age of rationalism and science as somewhat of a passing fad :x --froth^t 03:21, 10 October 2007 (UTC)

Please see the five minutes world (fourth quotation of the linked section), brain in a vat, and The Matrix... See also Wikipedia's article on science, which says that science is not supposed to and can not discover any truth. A.Z. 21:15, 12 October 2007 (UTC)