Wikipedia:Reference desk/Archives/Science/2010 July 25

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July 25

Ultra violet rays

Do ultra violet rays penitrate water? Any differnce between fresh water and salt water? Can a person get sunburned while swimming under water? —Preceding unsigned comment added by Wsccj8 (talk • contribs) 00:00, 25 July 2010 (UTC)

Yes. In fact many water purification systems depend on UV light. I don't think there is a difference between fresh and salt water, but murkiness makes a difference. You probably wouldn't get sunburned if you were more than a few feet down, but I get the worst sunburn of my life while snorkeling in the Caymans -- you don't have to spend much time at all near the surface for it to get you. Looie496 (talk) 00:37, 25 July 2010 (UTC)

Ultraviolet radiation can be sub-divided in several ways. One way is to sub-divide the ultraviolet family of radiation into ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). See Ultraviolet#Subtypes. UVA and UVB are the ones we are most familiar with, and they do not penetrate water for any significant distance. So sunburn is not a risk while underwater, but we mammals can't stay underwater continuously, and when we come up for air then we are vulnerable. UVC penetrates water and has application in disinfecting water because it is lethal to any living organism. See Ultraviolet germicidal irradiation. Fortunately UVC is not present in our environment because solar UVC is eliminated by the Earth's atmosphere! Dolphin (t) 01:06, 25 July 2010 (UTC)

You are mistaken. For wavelengths longer than ~200nm, i.e. UVA and UVB, there is little difference between the absorptivity of UV in liquid water than the absorptivity of visible light [1][2]. So, in practice, the UV is diminished by about the same amount that sunlight appears diminished. Hence, for most swimming scenarios, water offers very little protection. The one correction to this is that waters rich in organic matter and/or microorganisms, will attenuate UV faster than visible light, but that won't be common among the waters people usually choose to swim in. Dragons flight (talk) 07:29, 25 July 2010 (UTC)

I may be wrong, but I've always heard that water can act as a magnifying lens (or water droplets can) and focus UV rays on your skin, increasing the chances of getting a sunburn if you are wet as opposed to being dry. This may be urban myth though. – Kerαunoςcopia^◁_galaxies 16:01, 25 July 2010 (UTC)

Odd chemical reaction?

While on the road this afternoon, I ate a can of pineapple chunks packed in pineapple juice. Finding the fruit rather warm (it had been sitting in the car, unopened, for quite a while), I bought a bottle of Pepsi. After drinking most of the bottle, I returned to the pineapple; for the rest of the afternoon, I'd take a little of one, wait several minutes, take a little of the other, wait several minutes, take a little of the first, etc., until both pineapple and Pepsi were gone. Since that time, I've had an odd taste in my mouth; could a mix of the two substances produce an odd chemical reaction that would be responsible for this unique and long-lasting taste? Whatever it is, I know it's not harmful, so I'm not asking for medical advice. Nyttend (talk) 00:08, 25 July 2010 (UTC)

The taste is metal. You are not supposed to leave the pineapple in the metal can once it's opened. Pineapple juice is acidic enough to eat some of the metal in the can, and you can taste that. It'll be either zinc or steel (usually zinc). It's not toxic in low amounts, but don't do it often. I bet if you looked, you would see something like "After opening, store unused pineapple in a glass or plastic container in the refrigerator."[3] printed on the can. Ariel. (talk) 02:32, 25 July 2010 (UTC)

You probably mean tin not zinc - hence Tin can.83.100.252.126 (talk) 02:37, 25 July 2010 (UTC)

No I don't. Cans are not made of tin anymore, they are made of steel, and (when necessary) zinc coated. Ariel. (talk) 03:03, 25 July 2010 (UTC)

After doing some research, now I'm not sure about the zinc. I'm still pretty sure tin isn't used much in cans anymore. They seem to be steel coated either with plastic, or enamel. But no tin or zinc. Ariel. (talk) 03:16, 25 July 2010 (UTC)

There really isn't such a thing as a zinc coated food can. Zinc is too reactive. 'Lacquers' of various types are also used. A tin can is tin coated steel, aluminium, or coated steel. Just read Tin can. Tin is still used extensively.83.100.252.126 (talk) 03:18, 25 July 2010 (UTC)

Here's a proper reference (from 2005) [4] "Steel cans, often called "tin" cans because of their micro-thin tin coating, comprise more than 90 percent of the food can market" —Preceding unsigned comment added by 83.100.252.126 (talk) 03:23, 25 July 2010 (UTC)

Ariel, do you have a reference for that? I understand that many foods should be refrigerated once opened to prevent spoilage, but your reply suggests that the acid in the pineapple doesn't begin to leach metal from its container until opened. Is this because that reaction requires oxygen? Please explain. -- Scray (talk) 03:10, 25 July 2010 (UTC)

I do [5] yes - opened cans make it worse.83.100.252.126 (talk) 03:45, 25 July 2010 (UTC)

Most likely the metal isn't attacked by the weak acid, but the presence of oxygen converts it to the easily dissolved (in acid) metal oxide. --Chemicalinterest (talk) 18:41, 25 July 2010 (UTC)

Maybe tin in the pineapple and phosphate in the coke reacted to make insoluble tin phosphate which has stuck to your tongue? What is the taste like anyway? fizzy, metallic, fruity ??? 83.100.252.126 (talk) 03:52, 25 July 2010 (UTC)

Sorry, I can't really say: I've never tasted anything like it before, and I didn't really experience it when my mouth was empty. I should clarify — (1) I was done with the pineapple perhaps 30 minutes after I opened it; and (2) I didn't notice the taste with either Pepsi or pineapple in my mouth; it was only 1½ hours later, once I reached home and drank milk from my normal cup, that I noticed anything. Nyttend (talk) 04:23, 25 July 2010 (UTC)

Surprisingly no one has asked the obvious question that I've noticed; have you eaten that much pineapple that quickly before? Nil Einne (talk) 07:25, 25 July 2010 (UTC)

I'd guess it's something to do with taste bud burn out or overload, maybe someone can explain more.. Did the milk lack taste or 'wetness' - this is something I've occasionally experienced - my usual solution is to drink more milk until it tastes like milk again...83.100.252.126 (talk) 13:49, 25 July 2010 (UTC)

Nil — I ate it somewhat slower than I normally do; a complete can of pineapple, eaten out of the can, is a common part of my lunch. IP — the milk seemed as wet as normal, and it had a distinct taste; it's just that it didn't taste like milk normally does. Nyttend (talk) 00:11, 26 July 2010 (UTC)

I'm still pretty sure it's simply metal, and not some more complicated reaction - metal has a pretty distinct and very strange taste. Maybe a test. Leave some pineapple juice in the can in the fridge. A few times a day take some out and taste it (put some in a cup and let it warm up - it's easier to taste when it's room temperature). Also some vitamins have a metallic taste. Maybe you've eaten some and can compare? Ariel. (talk) 03:31, 26 July 2010 (UTC)

Okay I wondered if it may be some sort of allergy (several people in my family have some sort of oral allergy syndrome to pineapple which causes a funny tongue, I myself have some sort of mild reaction to prawns which gives what I describe as a metallic taste) but guess not Nil Einne (talk) 21:47, 27 July 2010 (UTC)

Absolute certainty

Is absolute certainty possible in science? For example, one of the fundamental axioms of relativity is that the speed of light is the same for all observers, but do we actually know this to be true beyond any doubt, or do we simply assume it to be true because we have never found a counterexample? Also, is absolute certainty possible in mathematics? For example do we know that $\ln(ab)=\ln(a)+\ln(b)$ is true for all a and b, or do we assume it to be true because we have never found a counterexample?--220.253.172.214 (talk) 03:14, 25 July 2010 (UTC)

Science is empirical. We gain evidence through observation, and extrapolate laws from the patterns we see in the evidence using inductive reasoning. This strategy can't tell things with absolute certainty, but for a lot of scientific claims we can be confident enough that for all practical purposes we can be certain. On the other hand it's been argued that induction has inherent flaws as a foundation for predicting how things will behave in the future (see Problem of induction). The math question is a bit trickier and I don't feel qualified to give a thorough answer so I will leave that to someone else. Rckrone (talk) 03:36, 25 July 2010 (UTC)

Absolute certainty is impossible. Are you absolutely sure you exist? Are you absolutely sure that what you are experiencing now is real and not a dream or a hallucination? Why are you so sure? How can you be so sure. At some level you must trust your own perception as reliable. Insofar as science is little more than the collective perceptions of humanity, organized into a certain system, we trust it. Science is as absolutely certain as it can be, given the limits of what certainty can be. It is also a flexible certainty, science at once expects its results to be reliable, and is also able to overturn past conclusions in the face of new, contrary evidence. --Jayron32 04:04, 25 July 2010 (UTC)

I contend that the empirical nature of science means that absolute certainty within science is impossible. However, I also contend that absolute certainty within mathematics is possible, because mathematical laws are derived from axioms which are defined such that they are true. For example, the equality operator "=" is defined such that $x=x$ is true for all x, and otherwise false. We can therefore be certain that $x=x$ for all x. This then becomes one of a set of axioms from which all other mathematical laws are derived, including for instance $\ln(ab)=\ln(a)+\ln(b)$. This means that we can be certain that $\ln(ab)=\ln(a)+\ln(b)$. Does anyone object to this or have anything more to add?--220.253.172.214 (talk) 04:17, 25 July 2010 (UTC)

No, you're talking about semiotics and not mathematics. You're defining the meaning of symbols, and declaring their absolute certainty. The definition of the equals sign is a linguistic issue, not a mathematical one. Again, your certainty with mathematics is still subordinate to your certainty of your own ability to trust your thoughts and perceptions, as well as the ability for the symbol to define the concept. You can trust mathematics to work only insofar as you can trust your perception of its own working. You still cannot escape your own mind, and so you must have faith that what you are experiencing in mathematical proof is really what exists. Furthermore, mathematics is not absolutely certain. All mathematical systems must be incomplete, and thus cannot be said to be completely certain. See Gödel's incompleteness theorems for more on these inherant incertainties in mathematics. --Jayron32 04:46, 25 July 2010 (UTC)

All right, absolute certainty is impossible, even in mathematics. However, some hypotheses must be more likely than others, otherwise science is pointless. Is there a way to quantify the probability that a particular hypothesis is true?--220.253.172.214 (talk) 05:09, 25 July 2010 (UTC)

"Absolute certainty" only exists within religions. The fact that their "certainties" vary from religion to religion is ironic, to say the least. The way to "quantify" a hypothesis is to perform experiments to see whether the hypothesis holds true. Science is a lot like math in that it relies on the concept of "if A is true then B follows". Consider geometry. The concepts of Euclidean geometry are absolutely true within that geometry. But you can create other geometries which have different truths. The likelihood of a given hypothesis being "true" would depend on the quality of the observations that support the hypothesis. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:20, 25 July 2010 (UTC)

By the way, I am familiar with bayes theorem which states that $P(H|E)={\frac {P(E|H)\,P(H)}{P(E)}}$, where H is a particular hypothesis and E is some new found evidence. This is generally the method used to quantify the probability that a hypothesis is true. However, how do we know that bayes theorem is correct if we don't have absolute certainty in mathematics? It would be ludicrous to use bayes theorem to quantify the probability that bayes theorem is correct.--220.253.172.214 (talk) 05:31, 25 July 2010 (UTC)

The "absolute certainty" you're seeking in math is based on "axioms" or "laws" which define the specific mathematics. IF those laws are considered to be true, THEN the mathematical theoreoms follow. If you want a "universal" absolute, science and math are not the places to go. The theories are subject to change based on new observations. As would be the above equation, I expect. If you want "absolutes", you need to find a religion that works for you. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:39, 25 July 2010 (UTC)

The truth of a mathematical statement is completely determined by the meanings of the symbols in it; it has no factual content and cannot be falsified by empirical observations. If a mathematical statement has a well-defined truth value, its truth value is independent of any minds perceiving it. I think Jayron's answer is confusing two questions of "certainty", namely (1) whether a subjective feeling of being convinced of the truth of a mathematical statement necessarily means that the statement is true, and (2) whether a mathematical statement involving an infinite number of cases is only true to the extent that no counterexamples have been discovered. I think the OP's question is about the latter, and the fact is, some mathematical statements can be demonstrated to be true under the intended interpretations using sound inference rules. Strictly speaking, Gödel's incompleteness theorems do not say that all axiomatic systems are incomplete—only those whose language is sufficiently expressive, but that's a technical detail that's not very important to the discussion here. It is important to understand the implications of Gödel's theorems correctly. Incompleteness only means that some statements are true yet not provable with a given (decidable) set of axioms; it doesn't mean that no true statements can be demonstrated to be so by means of a formal proof. --96.227.54.59 (talk) 06:54, 25 July 2010 (UTC)

Oh I see. So for instance, considering my original example, is known absolutely certainly that $\ln(ab)=\ln(a)+\ln(b)$ is true for all a and b?--220.253.172.214 (talk) 07:10, 25 July 2010 (UTC)

For negative a and b no: there's a problem. Maybe the simpler example e^a+b=e^ae^b .83.100.252.126 (talk) 18:55, 25 July 2010 (UTC)

I just want to add something regarding the Bayes Law question. There's an important distinction to make between the mathematical endeavor of proving theorems from axioms and definitions, and the scientific endeavor of tying to connect the math results to a physically meaningful description of the world. So for example "2 + 2 = 4" is a mathematical result, but "2 + 2 = 4" alone doesn't imply that if I have two apples and I acquire two more then I'll have four apples. First we have to establish empirically that this mathematical structure of integers and addition that we invented tends to reflect the physical process of gathering up discrete items, and that's a scientific problem. (Of course in practice the math concepts tend to arise to represent empirical properties rather than the other way around.) So the truth of Bayes Law as a mathematical theorem is separate from the idea of probability as a measure of certainty of empirical facts. Rckrone (talk) 07:14, 25 July 2010 (UTC)

Actually, you kind of answer your own question by saying "we simply assume it to be true because we have never found a counterexample." Science does not concern itself so much with what's "true" but with what works. There was a question here recently about the relative motions of celestial objects. It's possible to construct a geocentric model of the universe, and it worked for hundreds and hundreds of years. And in practical, everyday life, it still pretty much works. The current model of the solar system, the galaxy and the universe in general are based on what we know so far. Unless we become God, we can't ever say that a theory is "absolutely right". But we can say that it "works" - the model constructed from that scientific theory provides consistent results. Hence, it's "good enough" for now. If we find inconsistencies, we make more observations and more hypotheses. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:47, 25 July 2010 (UTC)

In Kantian terminology, the mathematical fact is an analytic a priori, whereas the physical law is a synthetic a posteriori. Nothing is ever completely certain, but the only doubt about the mathematical fact comes from doubt about the ability of thousands or millions of humans to judge the validity of a mathematical proof. Looie496 (talk) 05:58, 25 July 2010 (UTC)

I would dispute that. I consider mathematics to be synthetic rather than analytic. The assertion that it's analytic is the fundamental premise of logicism, which is essentially a failed approach to mathematical foundations. --Trovatore (talk) 07:19, 25 July 2010 (UTC)

Well, I don't want to be dogmatic, but it would clearly be wrong to say that we believe $\ln(ab)=\ln(a)+\ln(b)$ only because we don't know any counterexamples. There is some kind of distinction in there somewhere, however you would prefer to frame it. Looie496 (talk) 17:49, 25 July 2010 (UTC)

Is there anything at all that can be known absolutely certainly?--220.253.172.214 (talk) 06:53, 25 July 2010 (UTC)

How absolutely certain are you that this conversation between us is really happening, and not an elaborate hallucination? --Jayron32 07:16, 25 July 2010 (UTC)

No, but you can assume some things are true for convenience sake. And, if these assumptions are not contradicted by your continuing experience, nor do they cause problems later that undermines their convenience, then you can continue to assume they're true. Just make sure you continue to gather experience, and occasionally examine these assumptions in the light of it. You might also want to have a couple of back-up explanations that currently seem less likely, to compare with as you aquire more experience, and be ready to find another explanation that fits your experience better, if necessary. That's basically how science works.

You might be interested in reading some of René Descartes's work, particularly Discourse on the Method. The interesting thing is not his conclusion, but how he reaches it. 86.164.66.83 (talk) 17:38, 25 July 2010 (UTC)

How do you know that there is nothing that can be known? Surely that would constitute some form of knowledge.--220.253.172.214 (talk) 21:40, 25 July 2010 (UTC)

That would be an excellent rejoinder to a claim that no one has made, namely that we can be absolutely certain that nothing can be absolutely known. --Trovatore (talk) 00:42, 26 July 2010 (UTC)

Ah, my work with this one is done :) 86.164.66.83 (talk) 23:29, 25 July 2010 (UTC)

Science can not prove anything at all. Science can only disprove alternative possibilities. Googlemeister (talk) 14:38, 26 July 2010 (UTC)

Given the title and discussion, it may be more accurate to say we can find enough evidence to show something is extremely unlikely to be true/correct, but we can never say with absolute certainty it isn't Nil Einne (talk) 21:52, 27 July 2010 (UTC)

Type of Current in Landline

What type of current is there in telephone line. I tried to measure, I think it's something near 48 volts DC. Our article POTS, I think, says that too. I can light up a LED with it. But why can't I run a DC motor with it ?  Jon Ascton  (talk) 04:44, 25 July 2010 (UTC)

According to the POTS article the "subscriber loop typically carries a "load" of about 300 Ohms" - that would mean the current would always less than about 0.16A .. what sort of motor where you trying to use ? - a small can motor should still work on 0.16A 83.100.252.126 (talk) 13:37, 25 July 2010 (UTC)

This would be a good time to use the multimeter you mentioned above. The 200mA setting should be ok if the current is going to be less than 0.16A (that's 160mA) 83.100.252.126 (talk) 13:37, 25 July 2010 (UTC)

See also ringer equivalence number for a discussion of some of the standard/permitted loads on telephone lines. TenOfAllTrades(talk) 13:52, 25 July 2010 (UTC)

Bear in mind that a lot of places, especially the United States, have "pseudo-POTS" backed by VoIP on the service-side. In those cases, there may be a 48V ringer-circuit provided locally (via power supply fed by the utility electric grid), but not actually provided by the telephone distribution wire. In fact, in many parts of the United States, the only reason POTS still exists is because of legal mandate from the FCC; when possible, the service is replaced by cheaper VoIP equivalents, which do not distribute meaningful quantities of power on the signal lines. Nimur (talk) 00:13, 26 July 2010 (UTC)

That was a simple DC motor (taken from a toy car) that normally runs even on one cell (1.5 volt), but runs on as high as 12 volt also. I am in India. And my landline has actually DSL service also, that's I use it for internet as well. It is that type of service where awhile using internet you can use phone also i.e. the "voice" will not interfere with internet-process. Is that what you called "psuedo-POTS" ?  Jon Ascton  (talk) 14:07, 26 July 2010 (UTC)

It sounds like you are describing DSL, which often indicates that your phone-line has been upgraded (but in and of itself, DSL doesn't guarantee anything about the actual distribution-line hardware). You probably shouldn't be trying to draw power out of the phone line, either way; whether the power comes off the telephone distribution line or a local power-supply, the equipment is not designed to sustain a steady power draw. Why can't you run off a DC power supply or a battery, instead of the phone line? Nimur (talk) 16:35, 26 July 2010 (UTC)

The question is not of need, it's just the curiosity. If LED runs, DC motor should run too. Well, will putting a capacitor or resistor in parallel/series be of any help ? -- Jon Ascton  (talk) 12:01, 27 July 2010 (UTC)

LEDs can run on low voltages and currents eg 2V and 20milliamps or lower, which may not be enough for the motor.

No a capacitor or resistor will not help.

Measuring the voltage and current should give you the answer.87.102.43.171 (talk) 14:16, 27 July 2010 (UTC)

It's possible that there is an automatic cutout circuit when the load is too high - the motor might be triggering this.87.102.76.166 (talk) 16:27, 27 July 2010 (UTC)

Graph with an unexpected spike in it?

Many years ago, in what was probably the summer I took a year of chemistry I retained very little of, I remember being shown a graph of a smooth descending(?) curve that had an unexpected spike in it. It looked something like the graph here but I think(?) it dropped to zero at the origin. The quantity being measured was something absolute and objective, like specific heat versus the elements or something (forgive me if that is gibberish). The story was that for years people would do these experiments/measurements and due to the smoothness of the graph everywhere else they would disregard the spike that appeared at one data point, assuming it was an error. Then someone thought about what it meant if it wasn't an error, and discovered some new property. My prof was trying to make a point about the right way to do bias-free experiments, as well as possibly teach us something important, but apparently that last bit didn't work in my case.

I realize this is close to nothing to go on, but it might be one of those things that is blindingly obvious to someone in the right field and it's been itching my brain for years.76.105.238.158 (talk) 05:51, 25 July 2010 (UTC)

Not related, but a very famously wrong graph was the Ultraviolet catastrophe, a name given to the expected results when you calculate the wavelength of light emited by a blackbody radiation source compared to the intensity of the light. Classical physics predicts that blackbodies would emit light of infinite power in the ultraviolet range (hense "catastrophe", since infinite power is meaningless). It's one of the cornerstones in the development of quantum mechanics, which is a theory that much closely matches actual results in this realm. Another sort of "unexpected" result from graphs is the so-called Island of stability, which predicts that certain superheavy elements (not yet synthesized) would actually be more stable than lighter counterparts. The general trend is that heavier elements are progressively less stable than lighter ones. The island of stability is someone counterintuitive based on the trends of most of the transuranium elements. Again, not the answers you were looking for, but some examples of how unexpected results from graphs can be used to push forward scientific thinking. --Jayron32 06:25, 25 July 2010 (UTC)

Thanks Jayron... not what I was looking for, but definitely awesome. That island of stability weirds me out a little bit... isn't that sort of Ice_9-ish? 76.105.238.158 (talk) 06:59, 25 July 2010 (UTC)

Not really. Remember that most of the really big transuranium elements have half-lives on the order of microseconds or shorter. That means that you could have an element which is 1 billion times more stable, and it would have a half-life on the order of a few hours. That's the scales were talking about here. Long compared to most transuranium elements, but not truly "stable" --Jayron32 07:14, 25 July 2010 (UTC)

You get graphs of the sort you describe if you plot heat capacity (often called "specific heat" in older texts) against temperature and your sample undergoes a phase transition. They're important, because you're probably measuring the heat capacity at low temperature to calculate the standard entropy of the substance and, if you miss the phase transition, all your results will be out by a fixed error (the entropy change at the phase transition), which means that your thermodynamic equations won't "add up", even at normal temperatures. It could well have been a determination such as this that your professor was referring to – preferably some really important compound like water where you want the data to be as accurate as possible! Physchim62 (talk) 11:26, 25 July 2010 (UTC)

Pretty sure that's it, and it just got messed up with other things in my head. When I read your post I suddenly remembered the prof talking about how that extra energy had to go somewhere, which is where steam power comes in. How, if this thing didn't happen, the Industrial Revolution wouldn't have turned out the way it did for lack of the steam engine - no trains, no big mills. Thanks, Physchim62. (no idea how to mark a question 'resolved'...) 76.105.238.158 (talk) 06:36, 26 July 2010 (UTC)

The point your prof was trying to make (I assume) was about the objective assessment of data and how it relates to theory. A graph is just a visual representation of some aspect of a data set, a data set if just the observations made from a particular run of experiments, and an experiment is just an operationalization of a particular aspect of a theory. Now, what every scientist does is deduce - they start with a theory, operationalize it (i.e., construct a pragmatic, real-world situation in which the theory ought to be valid), and try to produce the outcomes they expect from the theory. The reason I say that's deduction is because that's what it is: the syllogism looks like this - theory A says X will always happen; condition Q is a case of theory A; X will happen in condition Q. What good scientists don't do is get blinded by their theoretical expectations. So, if a theory predicts a smoothly decreasing output function, and data produces a smoothly decreasing output function with an odd spike, a lot of scientists will assume that the theory is valid and the spike is a random phenomenon, and give it no further thought. A good scientist will step back and take the question "is that spike a random phenomenon or a real effect"' as a separate question and investigate it. Sometimes it will prove itself to be random, but sometimes it will prove itself to be real, and either way a lot of knowledge is generated. --Ludwigs2 12:53, 25 July 2010 (UTC)

Skyscraper cost

An interesting thought. Burj Khalifa is the tallest building with 828 metres height and 160 floors, Taipei 101 is second tallest with 509 metres height and 101 floors. But the second costs more ($1.8 billion) while the first costs $1.5 billion. Why a building with less height costs more than a building with more height, floors and architectural challenge? Any idea?? --Galactic Traveller (talk) 11:05, 25 July 2010 (UTC)

And I have a similar interesting and well thought out question: My Ford Super Duty sits more than 2 meters high (4WD), my neighbors Mercedes SLK is only 1.2 meters high. Yet my truck cost a 1/3 of the price of his car. Why a vehicle with less height costs more than a vehicle with more height, metal, and load carrying ability? Any idea? 68.28.104.251 (talk) 12:20, 25 July 2010 (UTC)

Why the cheap sarcasm? My question is a valid one. You cannot compare a luxury car with a general truck. But Burj Khalifa/Taipei 101 are different things than Ford Super Duty/Mercedes SLK. --Galactic Traveller (talk) 12:31, 25 July 2010 (UTC)

And I don't see how Taipei 101 is a "luxury" building (at par with Mercedes SLK), while Burj Khalifa an "economical" one (at par with Ford Super Duty). Your analogy is non-logical. --Galactic Traveller (talk) 12:34, 25 July 2010 (UTC)

You have answered your own question Travellller, you cannot compare the cost of the 2 buildings on height alone. As with my cheap, sarcastic analogy your comparison is non-logical. 68.28.104.232 (talk) 12:55, 25 July 2010 (UTC)

The question is almost impossible to answer - it involves too wide an assortment of factors. for example, if we assume to otherwise equal buildings, one built in an earthquake zone will be more expensive than one built in a different location; different kinds of soil structures require different techniques which will produce differential costs; different local economies will provide labor forces with different standards of living and different pay scales as well as divergent costs of materials. and in this case there is no reason to assume that these are otherwise equal buildings. This is on a par with asking why it costs more to raise a child in the US than it does in Guatamala - the obvious answer really isn't all that obvious at all. --Ludwigs2 13:05, 25 July 2010 (UTC)

Indeed. Some more factors: TP101 is mostly a box whereas the Burj is a spire, so while the Burj is much taller, the two have almost the same floorspace. So TP101's cost-per-square-yard isn't so bad as the cost-per-floors number would suggest - but then again high floors and spaces with greater proximity to windows rent for more, so that complicates an economic comparison of the two. TP101 has more elevators (but in different configurations, again confounding easy comparisons). Both are in hot, humid places, so both are going to need impressive AC systems, but which will cost more (again the shape and ratio of window to floorspace is a factor)? TP101 has to withstand typhoons, whereas the Burj has a rather tamer wind environment (and I guess much less rain). How much did the capital for each cost (that is, how much interest did the two construction companies have to pay to borrow the money to build the things). In addition to the differential labour costs Ludwig2 cites, there are different compliance burdens (healthy and safety, fire risk, security, structural redundancy). And then there's the downright risks of construction - I'd bet you could build two skyscrapers next to one another at the same time, using two high-quality contractors, and end up with final bills on the two that differ by at least 5%. -- Finlay McWalter • Talk 19:29, 25 July 2010 (UTC)

Our article, Construction of the World Trade Center, has some discussion of costs. Interestingly, the decision to build a duplicate building, with the same design across the street from the first did not strictly multiply the expected cost by a factor of two. The economics of large projects like a skyscraper are very "nonlinear." Nimur (talk) 00:29, 26 July 2010 (UTC)

TP101 also has to withstand strong earthquakes due to its location along one of the more active faultlines in the world, as such more sophisticated planning in structural engineering have to be done. As well the fact that Taipei is located on an ancient lake bottom also poses additional challenges. -- Sjschen (talk) 23:01, 25 July 2010 (UTC)

A more valid way to compare cost is by cost per square meter/foot, since the floors are certainly not equal in area or extent between buildings. In point of fact, Taipei 101 is more or less the same all the way up, while the Burj Khalifa gets narrower as it goes up. Construction costs in Taipei may be different, and the overall level of finish can vary by 50%. Further, are we comparing the same things? Construction cost vs. sale price? Finished throughout, or just shell space? Soft costs (financing, design fees, furnishings) vs. hard costs? There's no way to make a valid comparison without knowing all this. Acroterion _(talk) 00:51, 27 July 2010 (UTC)

explain the production of car in japan

explain the production of car in japan,electronic equipment in south korea and textiles in tanzania —Preceding unsigned comment added by 41.204.150.69 (talk) 14:19, 25 July 2010 (UTC)

From Wikipedia:Reference_desk/Guidelines#What_the_reference_desk_is_not, "The reference desk is not a service that will do homework for others." --Galactic Traveller (talk) 14:33, 25 July 2010 (UTC)

The article Big Three (automobile manufacturers) has a section on Japan and Index of South Korea-related articles contains links to relevant information. As your IP geolocates to Tanzania, I skip the last question. --Cookatoo.ergo.ZooM (talk) 22:34, 25 July 2010 (UTC)

Canine vs human rabies vaccine

Why is it that a vaccine protects dogs against rabies but humans who have PEP (pre-exposure prophylaxis) still have to get more shots after a possible exposure? Is it the case that both vaccines provide partial protection, but that we're more cautious in the case of humans? Rodney Boyd (talk) 14:44, 25 July 2010 (UTC)

In the human case, the virus potentially has a head start, and it may take a larger immune boost to suppress it. If rabies vaccine were given to dogs after a bite, they also would probably require larger doses. Looie496 (talk) 17:31, 25 July 2010 (UTC)

I'm not sure what you mean by the virus having a head start. Thanks. Rodney Boyd (talk) 22:47, 25 July 2010 (UTC)

I think he's getting at the fact that in most cases, humans bitten by a rabid animal have not had prior rabies shots. In many cases (in the United States) pet dogs have had prior rabies shots before they are bitten. Therefore, the rabies virus has more of an opportunity to replicate itself in humans before you get the injection, and your immune system (hopefully) learns how to recognize it. The question that I have though is that, in my understanding, if I have a dog that has had its immunizations dutifully kept up to date, and it gets bitten, it requires no further treatment - it is immune. Yet, even humans that have had prior immunizations (people who work in jobs that carry a higher risk of contacting rabies get a shot even without having previous contact with rabies) have to have shots after being bitten. What would the difference be between the human and the dog? Falconus^{p t c} 00:19, 26 July 2010 (UTC)

Thanks, but actually I just misunderstood the question. Looie496 (talk) 00:36, 26 July 2010 (UTC)

You're dealing with two different risk groups. For pet dogs, you are essentially vaccinating the whole population regardless of individual risk of contracting rabies; for humans, you only vaccinate people who have a higher than average risk of coming into contact with rabies, and you revaccinate those people who could have come into contact with the virus. Because the risk factor for rabies is higher for the humans whom we choose to vaccinate, the use of a more aggressive protocol is justified. No vaccine provides 100% protection, and all vaccines have potential side-effects – if they didn't, we'd all be vaccinated against everything we can vaccinate against! Physchim62 (talk) 00:58, 26 July 2010 (UTC)

Some medical sites--perhaps erroneously?--state that if you're bitten by a dog that has its shots up to date, then no worries. Is this meant to imply that the canine shots are ~100% effective, or just that the probability that the dog was exposed to rabies x the probability that the shots *didn't* protect it are infinitesimally small? Rodney Boyd (talk) 01:46, 26 July 2010 (UTC)

I would go for the latter explanation. I don't have any figures for the effectiveness of the canine vaccine, but there's always some variation between individuals (and vaccine batches) so you never get to exactly 100% effectiveness. The latter explanation works better: most domestic pets will never be exposed to rabies, and those that are should be immune, so you would have to be extremely unlucky indeed to be bitten by a "double exception". If we were really so risk-averse as a society, private motor vehicles would be banned ;) The major risk to humans is from wild-animal bites, which is why people who regularly come into contact with wild mammals are vaccinated. Physchim62 (talk) 17:28, 26 July 2010 (UTC)

Don't forget expense: the rabies vaccine is very expensive! (though I seem to recall that there's an older kind of rabies vaccine that's cheaper but very painful) The nearly-100% mortality rate of rabies once symptoms appear makes it more attractive, though... [edited to rephrase] Paul (Stansifer) 05:13, 26 July 2010 (UTC)

You have to weigh up the expense of the vaccine with the expense of treating rabies victims (and the lost benefit to society of those who die). As for side effects, you weigh up a "cost" of side effects (which might include a small risk of death) to the "cost" of not being even partially immune to rabies. The balancing act is not always devoid of controversy when you're talking about an entire population... Physchim62 (talk) 17:28, 26 July 2010 (UTC)

Ropinirole

What is the shelf life of the drug called Ropinirole? —Preceding unsigned comment added by Hkjagtiani (talk • contribs) 15:05, 25 July 2010 (UTC)

1 year or 18months depending on packaging, see [6] 83.100.252.126 (talk) 15:24, 25 July 2010 (UTC)

Compressed sound of a jetliner

I suppose on a windless day, we can all hear the sound of a jetliner flying overhead, a steady drone rumbling high above. That rumble will increase in volume as the plane passes by, and decrease in volume, the sound dragging along far behind, not unlike an aural "chip log". But sometimes—and I'm assuming it's wind currents playing heavily—the sound of the plane reaches our ears at a compressed rate; the plane will be farther along in its travels and the sound still won't have reached the ground just yet. But when it does, the incidental sound resembles a loud engine throttling down, from high frequency to low frequency in a matter of only a few seconds. I don't know how else to describe it. It could be like the sound of a semi-truck's engine and wheels on the road as it comes to an abrupt stop. One could almost think it's a fighter jet (less screeching) approaching quickly, but as the frequency of the sound reaches that familiar low droning, it's like it has uncompacted and "caught up" with the jetliner's regular sound, and the plane will fly off sounding normal as usual. My two questions are—if I've made myself clear—how is this sound caused, and does there happen to be a word for it? Thank you! – Kerαunoςcopia^◁_galaxies 15:56, 25 July 2010 (UTC)

Doppler effect is I think what you want. Mikenorton (talk) 15:59, 25 July 2010 (UTC)

Maybe it just boils down to that. Thx. – Kerαunoςcopia^◁_galaxies 14:58, 26 July 2010 (UTC)

household / domestic sonicators

I am in love with glassware sonication. Why hasn't it taken off for household use -- to wash dishes in a sonicating sink? It would seem very antimicrobial too -- you could lyse any biofilms. Most laboratory units seem to go for over a thousand dollars but I bet costs would drastically decrease with mass production. John Riemann Soong (talk) 16:10, 25 July 2010 (UTC)

You mean like these google shops or google shops - spot the 1000-10000% mark up on the ones for scientific use. ok so they house-hold ones are only big enough for jewelry or 1 glass.

Why hasn't it taken off? - maybe it doesn't work on a tub full of plates and pans with pasta on - too heavily loaded. They are used industrially for cleaning metal components etc in engineering - but loadings are not the same as people expect in a dishwasher or hand washing bowl.83.100.252.126 (talk) 16:31, 25 July 2010 (UTC)

It seems to me more of an engineering problem than a concept problem. Do sonicators use a narrow range of frequencies? Do they alternate the frequencies up and down for maximum effect? Do they try to employ resonance? John Riemann Soong (talk) 16:42, 25 July 2010 (UTC)

One possible barrier is that sonication requires the dishes to be totally immersed in water - that would be a lot of water for a dishwasher , even before rinsing.

At least one manufacturer uses variable frequency as an option [7]

Resonance is (I think) the way in which the cleaning cavities are produced, but resonance of the object to be cleaned can be a problem [8], also standing resonance can produce areas which are constantly cleaned can cause cavities and pitting of the thing to be cleaned.83.100.252.126 (talk) 21:06, 25 July 2010 (UTC)

Evolution

Evolution says that organisms should do whatever it takes to ensure that their genes are passed on, so doesn't this mean that, if evolution is true, then rape is not only acceptable, but desirable? --138.110.206.101 (talk) 16:11, 25 July 2010 (UTC)

That would be a naturalistic fallacy, see also appeal to nature. The acceptability or desirability is an ethical question. Though we might be able to use the theory of evolution to explain certain animal behaviour such as rape, the theory cannot be applied to the (im)morality of rape committed by humans. ---Sluzzelin talk 16:16, 25 July 2010 (UTC)

From an evolutionary perspective, it's also great to take others' spouses, food, housing and belongings and perhaps even kill the previous offspring of the spouses that you snatch. Plead innocent on the basis of evolution and let me know how that goes :) DRosenbach ^{(Talk | Contribs)} 16:33, 25 July 2010 (UTC)

what is best in life :) 83.100.252.126 (talk)

DRosenbach, that's not really true, anyway. Human beings are social animals. We cannot survive on our own, we depend on at least a tribe, and ideally a larger civilization. Natural Selection will tend to select against people who don't properly participate in that society. APL (talk) 18:09, 25 July 2010 (UTC)

All you're doing is utilizing the present circumstance of human society to justify the present circumstance of human society -- circular logic indeed. We may choose what we like, whether it be more evolutionarily efficacious or not. Lions are pretty social animals, and it's reported that adult males may kill off offspring of other males. We certainly can survive on our own and even if we prefer to live in a tribe consisting of more than one male with a harem of females, that says nothing of the treatment one tribe would offer another tribe. DRosenbach ^{(Talk | Contribs)} 18:26, 25 July 2010 (UTC)

Lions sorta lack the level of sophisticated thought, memory, communication and action we do therefore what works well for them doesn't necessarily work well for us. For example, if a lion kills the offspring of other males, the females will still usually fairly willing mate with it when they enter heat. They aren't likely to hold a 'grudge' against that lion forever more. If you kill a woman's children because they were with other males, you'll likely get locked up and there's a very good chance that woman and most other women who are aware of what you did aren't going to be particularly happy to mate with you unless perhaps you convince them it was a mistake in your past. (In the past, you'd may have been kicked out of the tribe and forced to live on your own or find another tribe, or even killed.) If you force them, you may be locked up again and the woman even if she gets pregnant may have an abortion. Even if she doesn't the children of rape will often be raised by solo mothers, given up for adoption or enter foster care, or otherwise in a less likely to be successful environment then the children of a happy relationship (or even the children of an affair with a woman in such a relationship). In other words, none of this is particularly good for you when it comes to spreading your genes. A smart judge may point out the fatal flaws in your logic if you do try to plead 'evolution', perhaps a simple 'well we'll see whether being locked up in jail is good for your genes from an evolutionary perspective' or 'thanks for agreeing you should be locked up'. BTW 'preference' has nothing to do with it. Humans have apparently evolved to live in a societal manner, presemuably because this was the most successful pathway as we evolved. Perhaps we could have evolved to liveout our lives primarily as individuals, but we didn't. Nil Einne (talk) 20:27, 25 July 2010 (UTC)

I don't claim that our society has to be exactly like it is now, or even that our ideals of ethics and morality have to be exactly like they are now. That would be a foolish statement. I claimed only that human beings instinctively try to survive in groups, and that such behavior is selected for. The details of how we organize those societies falls largely to the logical section of our brain, which is a good thing, because tribal life doesn't scale well. APL (talk) 21:05, 25 July 2010 (UTC)

Evolution doesn't say anything about what organisms should do, it just explains what they do do. It says that animals that do everything they can to pass on their genes are more likely to pass on their genes, so the next generation is more likely to be made up of animals that do everything they can to pass on their genes.

It's not even necessarily true that evolution will select for rape. You don't just need to have children, you need your children to survive to have children of their own. Since, in the case of rape, the female hasn't chosen a male that she thinks will provide good children (I am assuming we are discussing a male raping a female, but the sexes can be reversed without harming the argument) she may conclude that it is better to not waste effort on this child and to have other children with a chosen mate instead (she may even abort the pregnancy). That means the male may have a better chance of having successful children if he works to convince a female that he is a good mate.

Also, rape will usually involve the female having (or potentially having) multiple sexual partners, which makes determining the father of any child difficult. That means males are not likely to be involved in the upbringing of children (since they can't be sure it is their child they are using resources for), which reduces the likelihood of those children surviving to adulthood. --Tango (talk) 16:37, 25 July 2010 (UTC)

Don't also forget things like the action of other males towards the children (which is bad enough in most species even without rape as an issue), or, as a point to hit home with in the human example, the action of other males and females towards would-be rapists. (Rape amongst humans, for example, would probably result in your genes being selected against in any society with accessibility to abortions and rigorously enforced anti-rape laws. Prison isn't a place to pass on one's genes, generally speaking.) --Mr.98 (talk) 17:13, 25 July 2010 (UTC)

(edit conflict) similar to above : No. Evolution does not say that organisms should do whatever they can to pass their genes on. Organisms do whatever they want.. which ever behaviour results in them succesfully passing their genes on in the long term is evolutionarily successful.

The human aspect has been pointed out above - for animals (for which sex can often be violent) other factors are important - such as caring for offspring in higher animals, and general survivability. Being a 'rape machine' might be one way to pass genetic material on, but is not necessarily linked to success. - any beast can reproduce itself - but 99% of life involves escaping from enemies, feeding oneself, reaching higher branches, catching mice etc. 83.100.252.126 (talk) 16:48, 25 July 2010 (UTC)

I also recommend this article as a good starting point to the logic: while I'm not sure I'd often use that site, the author of this particular article and the links given within it make it helpful. And, of course, even if rape were evolutionarily advantageous (which I don't think it is), that wouldn't mean you should do it. 86.164.66.83 (talk) 16:56, 25 July 2010 (UTC)

Evolution is not a source of moral guidance, just an explanation of what has happened to in the past. APL (talk) 18:09, 25 July 2010 (UTC)

To take your point further, evolution is antimoral. There are no ethics if man is the highest animal and therefore does what he wants. Ethics only exist because of someone higher than man who dictates what is right and what is wrong. --Chemicalinterest (talk) 18:49, 25 July 2010 (UTC)

No, evolution is amoral – it does not care about morality, which is a purely human construct. Physchim62 (talk) 19:00, 25 July 2010 (UTC)

In hunter-gather societies you depend on your fellow group members. You must trust them and they must trust you. If you are caught cheating (stealing food, not taking a big enough part in the hunts), you will likely be shouted/snarled at. Keep doing it and you will be thrown out of the group. You are likely to starve to death as a result. That selects genes for detecting cheating and against cheating, at least at cheating enough to be caught. 62.56.49.134 (talk) 19:19, 25 July 2010 (UTC)

Certain big cats fight over what they catch all the time, with sometimes one "stealing" what another caught. Certain lazy animals just eat what the hard-working ones catch. --Chemicalinterest (talk) 10:49, 26 July 2010 (UTC)

Interested parties might like to read Evolution of morality. 62.56.49.134 (talk) 19:53, 25 July 2010 (UTC)

Ethics does not require a god or gods to dictate it. Atheists can be just as moral and ethical as theists. You could consider "society" to be "something higher" that dictates what is right and wrong, but there is certainly no need for a "someone higher". --Tango (talk) 20:04, 25 July 2010 (UTC)

It is indeed society (or inbuilt god given guidance) that makes ethics exist: a single human being has no need for ethics/morality since they have nothing to apply it to. Some philosophers such as Mencius are interpreted as saying that humans have inbuilt good morals. Others (see Legalism (Chinese philosophy) also Xun Zi) say that humans are intrinsically bad, and it is society that prevents evil. The bible presents evil as an abuse of man's free will on the instigation of the devil; which I think is somewhere inbetween. Biologically it's easy to interpret ethics as an extension of a built in natural instinct not to kill and eat things that look like you - which even some very simple animals respect. 83.100.252.126 (talk) 20:37, 25 July 2010 (UTC)

Tango, I'm not sure you even need that. It seems like some combination of humans' natural instincts for empathy and cooperation combined with our ability to ponder the logical question "What if everyone did this?" would come up with a usable, if not perfect, system of ethics. APL (talk) 21:14, 25 July 2010 (UTC)

Ah, but if morality was a natural consequence of human nature then all humans would have the same sense of morality, but that isn't the case. We consider slavery to be highly immoral now, but humans in the same countries not all that long ago felt differently. Since different societies have different moralities, society must come into it somewhere. --Tango (talk) 21:46, 25 July 2010 (UTC)

Chemical, that does not "take [my] point further". You just responded to what I said with canned religious dogma that was pretty much the opposite of what I said. Evolution has no more to do with morality (good or bad) than any other scientific explanation of the world around us. (Say, electromagnetism, Or atomic theory.) APL (talk) 21:04, 25 July 2010 (UTC)

canned atheistic dogma--Chemicalinterest (talk) 10:49, 26 July 2010 (UTC)

Matthew 5:9,22,46 7:3-5 10:14 22:20-21 23:5 And, of course, Ecclesiastes 3:15 is why the internet sets up FAQs like you can find at the talk.origins archive, rather than trying to draw people into yet another rehash. 86.164.66.83 (talk) 23:46, 27 July 2010 (UTC)

Troll thread. Why are people replying to this shit? 82.43.90.93 (talk) 21:11, 25 July 2010 (UTC)

Refusing to consider and discuss something because we find it morally objectionable is not a good way reach the most effective conclusions about things. --Tango (talk) 21:46, 25 July 2010 (UTC)

(Edit Conflict) Disagree, 82; although we can't mindread the OP, who might have had trollish intent, the question is a perfectly valid one in evolutionary, biological and sociological terms and, on the principle of assuming good faith, should be addressed. 87.81.230.195 (talk) 21:48, 25 July 2010 (UTC)

The article Social Darwinism may be relevant. Is life all about nice v. nasty? 92.29.117.139 (talk) 23:54, 25 July 2010 (UTC)

The fact is that there are animals where rape and killing the children of other males and all manner of "nasty" behaviors have been evolutionarily effective - but then there are other animals (like Meerkats, for example) where a remarkably human-like society has evolved. The reason why one strategy works for (for example) lions and a different one works for humans and meerkats is complicated. It is in the interest of a gene to produce an animal (or plant or whatever) that not only reproduces itself effectively - but also avoids killing off other copies of itself. In many small-society animals, there is sufficient inbreeding that killing off the offspring of another pack member is more likely to reduce the spread of the 'murderer's genes than to increase it by relieving competition. Humans are pack animals - and it's very likely that we've evolved our sense of moral outrage for precisely this kind of reason. Lions have a very different life-style though. The male offspring of a pack go off on their own as 'loners' into the wilderness for many years before finding a pride that he can take over by beating off the incumbent male. Having done that, killing all of the cubs of the previous male is a worth-while strategy. Using the word "rape" to describe what happens to the females of the pride is a little contentious because it's a very loaded word...but I suppose you could apply it there.

The point is that our system of instinctive morals has evolved as a result of what works best for our society...and we very often viciously attack members of our species who have any kind of alternative moral sense.

SteveBaker (talk) 02:04, 26 July 2010 (UTC)

That's an unfortunate example: I saw a documentary a few weeks ago in which a female meerkat killed the young of another female in order to force the group to concentrate its efforts on her young instead. --Tango (talk) 02:26, 26 July 2010 (UTC)

There was a scholarly paper written on this within the last few years that attracted a lot of the same political attention. I agree with the moral fallacy arguments above, and would point out too that part of why these sorts of aggressive evolutionary mechanisms aren't prevalent today is probably a good reason why they weren't prevalent (or at least acceptable) in pre-industrial times: there are very severe consequences for them. In pre-industrial times it probably meant the victim's family punishing the perpetrator. In modern times we've outsourced that function to the state, but the end result is similar. Shadowjams (talk) 07:04, 26 July 2010 (UTC)

"Morals" in animals are the result of instincts, while morals in humans are not. Humans decide what they do by their own free will. God gave us a plan of morals. Over the years, man has violated it. Seeing that God has grace on men and so generally does not punish violations in this life, they make bigger violations, thereby defining their moral code. So at first it was life for life in the case of murder. Then it became just imprisonment. Then the killing (yes it is killing) of unborn infants became legalized in expanding proportions. Then the killing of old people became legalized in some countries. Sometime it might be the killing of anyone you do not like is tolerated. Saying that since God is not existent (and therefore it is safe to violate him) is like standing in front of an old cracked dam bulging with water and saying that since the water is not visible, it is safe to live there. --Chemicalinterest (talk) 11:01, 26 July 2010 (UTC)

Please do not proselytize here for your particular belief system based on a god. This is not a forum to discuss your conviction that atheism implies a lack of morality.. Cuddlyable3 (talk) 11:44, 26 July 2010 (UTC)

(EditConflict) CI, I can see that you have deeply-held religious views on this matter. However, I contend that humans' innate sense of morality is from our genes, not a supernatural being. Just as we have a far greater emotional response that other animals, we have a greater moral code, and can contend subtleties more. These are part of our ability to put ourself in another's shoes, i.e. theory of mind, and empathise with them. I can't remember the technical term just now. IIRC, 3 year-old children, chimps and some dogs and cats can tell if a person they are interacting with is 'playing fair', which is part of a moral code, "Thou shalt not cheat". CS Miller (talk) 11:53, 26 July 2010 (UTC)

We can place ourselves in another's shoes, and know what it would be like to be on the receiving end of our actions. By understanding we wouldn't like this, we know that we shouldn't do that action on another. CS Miller (talk) 12:20, 26 July 2010 (UTC)

OK I might have got it wrong. Atheism does not mean there is no morals; it means that you are your own god and you make your morals for yourself. Whatever feels right to you goes. Which I consider a lack of morality because humans can dull their consciences to accept things that they used to not feel right doing, thereby changing their moral code. I am presenting my beliefs beside yours so people can have a choice as to which they will believe. --Chemicalinterest (talk) 12:45, 26 July 2010 (UTC)

I'd still contend that some morality is innate. Moral universalism states that basic morality is the same for all societies, which is probably based on the golden rule, which itself comes from empathy. However, short of raising a group children with no adult contact, there is no easy way to prove it. Such an experiment would be highly unethical. CS Miller (talk) 12:57, 26 July 2010 (UTC)

This is a popular mistake, and I don't blame you for making it, but you seem to be confusing 'atheism' (a lack of belief in the existence of a deity or deities) with a lack of an ability to follow (or establish) a fixed moral framework. Our article on secular humanism – which is one of the organized frameworks or creeds one might choose to live within as an atheist – has this to say:

Fundamentalists correctly perceive that universal moral standards are required for the proper functioning of society. But they erroneously believe that God is the only possible source of such standards. Philosophers as diverse as Plato, Immanuel Kant, John Stuart Mill, George Edward Moore, and John Rawls have demonstrated that it is possible to have a universal morality without God. Contrary to what the fundamentalists would have us believe, then, what our society really needs is not more religion but a richer notion of the nature of morality. - Theodore Schick, Jr.

On the flip side, all Christians are supposed to be reading (literally) from the same books, but we have the loose-nut wackjobs of the Westboro Baptist Church ("God hates fags!" "God: USA is terrorist!"), the Roman Catholic Church (which treats the sexual abuse of minors and the attempted ordination of women as equally serious matters), and the United Church of Canada (Canada's second-largest church, which has ordained women since 1936, supports women's access to safe abortion, and endorses same-sex marriages) who are somehow all in the same tent. Should you eat meat on Fridays, or shouldn't you? Is alcohol a sin? What about dancing? How about women wearing trousers? There is a centuries-old tradition of forking existing religious frameworks when one gets tired of particular tenets (or wishes to impose new rules or interpretations). If it is immoral for an atheist to establish his own moral principles to live by, it must surely be equally immoral for a theist to elect to change denominations or convert between religions — he would be making a principled decision that the previous rules he lived by weren't correct, just like that dirty, self-guided atheist. TenOfAllTrades(talk) 14:44, 26 July 2010 (UTC)

Yes I see that Christians have the same problems because following what God has stated in his word is too hard. --Chemicalinterest (talk) 17:52, 26 July 2010 (UTC)

That may be a problem for Christians, I don't know: I guess it must be hard, as so many Christians so obviously fail to follow what they claim to be the inspired word of God. That has nothing to do with the evolution of morality, however. If morality were a Christian invention, we would have blatently different moral codes between human societies, and yet we don't. Not only are basic moral codes remarkably similar among human societies, we can also find partial parallels among other species, and not simply among primates, or even simply among mammals. Physchim62 (talk) 18:08, 26 July 2010 (UTC)

That is not true. Moral codes vary widely. Examples: Honor killings, Bride burning, killing unwanted children by exposure, abortion, bride kidnapping, different laws for different social classes, human sacrifice, slavery, elder suicide, euthanasia, there's tons more. Ariel. (talk) 18:41, 26 July 2010 (UTC)

I can't think of one issue on which all members of any major religion agree on. Hell, Christians can't even agree on what makes a person a Christian. 67.243.7.245 (talk) 19:35, 26 July 2010 (UTC)

To support Physchim62's point, the peoples of the world started as one. They then split up at the building of the Tower of Babel, where each group (i.e. language) has the same ideas but a different language. Each group (and their morals) gradually change over time, supporting Ariel's point. --Chemicalinterest (talk) 21:39, 26 July 2010 (UTC)

Chemicalinterest, this is the SCIENCE Reference Desk. You have made statements on this thread such as:

• what God has stated in his word
• the peoples of the world started as one
• They then split up at the building of the Tower of Babel

These are obviously things that you believe. I suggest you believe them because authoritative and influential people have told you these things. You are an obedient young man and you believe what these people have told you. But that does not make them science. Science requires evidence from more than one source. Please confine your comments on this Desk to ideas that can be independently verified from more than one source. That will be appreciated. Dolphin (t) 22:49, 26 July 2010 (UTC)

ChemInterest, I wish you'd stop saying things like "To support so-and-so's point" or "expanding on what-his-name's remark" and then going off on an unrelated religious diatribe that the poster whose name you've invoked would obviously not agree with. APL (talk) 01:30, 27 July 2010 (UTC)

APL, I was corrected by the first user I referred to. The second one had a different meaning. I didn't say that they would agree with my point; I just was showing how the Bible corresponds perfectly with history. Dolphin51, to respond to your point; people give evolutionary explanations because authoritative and influential people have broadcasted these things in scientific journals and the like. I was also saying that the Bible's account of the history of man corresponds perfectly with the evidence of man's past, which means that science and the Bible are friends, not enemies.

I thought it was only the old Catholics that hated being told that the earth was round, not the modern day squelchers of belief. Even the creationists allowed Darwin's point in, though not without debate.. Morals and origins--neither of those are sciences. They are both philosophy, which is not science. Philosophy vs. science is like thinking vs. how you think in your brain.

End note. I have not had anyone help me with any of these discussions, give me suggestions, etc. This is just what logically occurs to me when I think of the world. --Chemicalinterest (talk) 10:47, 27 July 2010 (UTC)

The Bible and science do not agree. I won't enter into an argument about this, though, it's too close to arguing about whether 2+2=4 anyway. I will, however, point out that religious morality, at least of the type found in most religions, is just an extension of egoism. It basically orders you to do X, because a certain boss will reward you for it, and to refrain from Y, because a certain boss will punish you for it. This becomes an issue of your own self-interest rather than caring about others. Atheist morality is, in the typical case, about doing X and refraining from Y out of empathy or benevolence towards other human beings, even though you don't expect any rewards or punishments for yourself, ever (altruism). There's another thing - while atheist morality, being based on empathy and benevolence, can only include principles that are based on empathy and benevolence towards other beings, religious morality, being based on the whim of a certain boss and not on any objective principle, can include any arbitrary command, including things that are indifferent or harmful to other human beings. Christianity seemingly incorporates real morality (love thy neighbour), but still dominated by the framework of religious morality, with rewards and punishments (love thy neighbour or else the good boss will torture you for all eternity), as well as arbitrary commands (do nothing on Saturday Sunday, don't be gay, recognize that Jesus existed, was born of a virgin, is the Messiah of the Jews, is son of God, is coeval with and equal to his own father, etc.). --91.148.159.4 (talk) 14:13, 27 July 2010 (UTC)

And then there's another point - not only do most forms of religion exclude real morality (i.e. unselfish morality) for its worshipers, but they also exclude morality for the god they worship. I mean, of course, the issue of theodicaea, God himself being omnipotent and yet allowing bad things to happen. God can't be both all-good and all-powerful - and most religions opt for the second alternative, the all-powerful one (the only theistic religion I'm aware of that doesn't do that is Zoroastrianism, most clearly in its mediaeval form). The god of most religions is (all-)powerful, hence clearly not good - indeed he has an unspeakable, unfathomable amount of guilt on his shoulders - yet he hypocritically requires to be considered good, thereby introducing a most perverted, Orwellian, sacrilegious notion of goodness. Saying it is possible, in this world, for a creature to be both omnipotent and all-good is a blasphemy against goodness - against morality. If you worship this putative creature, you really worship absolute Power despite the fact that it is amoral. Basically, this means you worship Satan. It's not atheism that is amoral; it is religion. The reason many people reject religion is not that it is too moral for them; it is that it is, among other things, too amoral for them. It is paganism.--91.148.159.4 (talk) 18:28, 27 July 2010 (UTC)

I'm not sure your use of the word 'paganism' is entirely appropriate, 91. I've met plenty of people who identify as Pagans, following consciously modern reconstructed (or invented) versions of Celtic Wicca, Druidism, Odinism, Religio Romana, etc (which mostly do not feature 'all-powerful' deities) and they're amongst the most moral and thoughtful people I know. A precept such as the Wiccan Rede "Do what you will [= consciously decide to do] so long as it harms no-one [including yourself]" doesn't leave much room for behaving inconsiderately towards other people, let alone persecuting them for following different religious paths, or otherwise misusing power over them. 87.81.230.195 (talk) 00:00, 29 July 2010 (UTC)

Achilles tendon humans vs animals

The other day I was watching my dog. I observed that he has a small "foot" (i.e. toes) with the "ankle" higher up. This got me wondering if the tendon between the "foot" and the "ankle" was the equivalent of the human Achilles tendon (same with horses, cows, goats, sheep, cats, etc.). If so, what is the "evolution" of this difference in anatomy? —Preceding unsigned comment added by 99.250.117.26 (talk) 16:29, 25 July 2010 (UTC)

This might help. DRosenbach ^{(Talk | Contribs)} 16:34, 25 July 2010 (UTC)

The evolution of humans and horses diverged in the split between Laurasiatheria and Euarchontoglires, probably about 90 million years ago. The bones of the legs can still be matched up, but the muscle and tendon arrangements have diverged so radically that there is really no way of matching any part of horse anatomy with the human Achilles tendon. Looie496 (talk) 17:14, 25 July 2010 (UTC)

Triple Slits, Born's Rule, and Sum over Histories

There's been recent news reports (e.g. [9]) of the results of the triple-slit version of the classic double slit experiment. These write-ups all tout the results, showing interference between pairs of slits but not all slits simultaneously, as confirmation of Born's Rule. However, reading that Wikipedia article there doesn't seem to be any indication that, as claimed in the ars technica article, Born's Rule implies "quantum interference can only occur between pairs of probabilities". Additionally, my lay-man's understanding of quantum mechanics, specifically the Sum over histories approach as presented in from Richard Feynman's QED: The Strange Theory of Light and Matter, would seem to indicate that the particle can and should move through all three paths simultaneously. Could anyone provide a (non-technical) explanation as to why Born's Rule, as presented in the Wikipedia article, would imply that quantum interference would only occur between pairs of particles, and what this implies for the sum over histories approach? Specifically, if the sum over histories view is still valid, why doesn't it imply that interference should occur for all paths, rather than just two? Thanks. -- 174.24.222.181 (talk) 18:17, 25 July 2010 (UTC)

So, I'll admit that I didn't read all of the article but I think this is just a problem of terminology. The article looks at 3 slits (labelled $A,B,C$) and imagines a wavefunction associated to the photon passing through each slit ($\psi _{A},\psi _{B},\psi _{C}$). Now the probability of observing a photon at the detector, $P_{ABC}$, can be composed via Born's rule as

$P_{ABC}=|\psi _{A}+\psi _{B}+\psi _{C}|^{2}=|\psi _{A}|^{2}+|\psi _{B}|^{2}+|\psi _{C}|^{2}+I_{AB}+I_{BC}+I_{AC}$

where they've defined $I_{MN}=\psi _{M}(\psi _{N})^{*}+(\psi _{M})^{*}\psi _{N}.$ When they say that interference only occurs between pairs of probabilities they just mean that each $I_{MN}$ term only couples two paths together. They go on to define

$I_{ABC}=P_{ABC}-|\psi _{A}+\psi _{B}+\psi _{C}|^{2}$

and their experiment confirms that $I_{ABC}$ is (to the accuracy of their experiment) zero. Just like we expect from good-old quantum mechanics. Martlet1215 (talk) 22:46, 25 July 2010 (UTC)

I'll just add that the introduction to the Science article is very readable if you can access it [10]. Martlet1215 (talk) 22:54, 25 July 2010 (UTC)

Since you've read QED you know that the amplitude of finding the particle at a location is given by the square of the length of the sum of a bunch of arrows, one for each path. Mathematically, the angle through which one of these arrows turns is called S(γ) (where γ is the path), the arrow is e^{i S(γ)} (a complex number), and the square of the length of the sum is

$p=\left|\sum _{\gamma }e^{iS(\gamma )}\right|^{2}$

Since |z|² = z z^* (where * is complex conjugation), this can be written

$p=\left(\sum _{\gamma }e^{iS(\gamma )}\right)\left(\sum _{\gamma }e^{-iS(\gamma )}\right)=\sum _{\gamma _{1},\gamma _{2}}e^{i(S(\gamma _{1})-S(\gamma _{2}))}=\sum _{\gamma _{1},\gamma _{2}}\cos \,(S(\gamma _{1})-S(\gamma _{2}))$

You can measure cos (S(γ₁) − S(γ₂)) with a two-path interference experiment, and once you know its value for all pairs of paths you have everything you need to compute all multi-path interference probabilities. The nice thing about this approach is that it deals entirely with physical, measurable quantities. You can't measure S(γ) or e^{i S(γ)} or ∑ e^{i S(γ)}—they contain "unphysical degrees of freedom"—but you can measure p and the cosine. The same trick works elsewhere in the Standard Model and also in general relativity (in GR, you look at the relative precession of a gyroscope transported along two different paths). If you like this stuff (I know I do), you might be interested in my post in Wikipedia:Reference_desk/Archives/Science/2010 February 13#magnetic vector potential actual meaning?. The twisting circles I talk about there are closely related to Feynman's rotating arrows. You can think of the arrow as pointing from the center of the circle to a point on the circumference. It tries to retain its orientation like a gyroscope, but because of the twisting of the circles, when you transport the same arrow along two different paths it ends up pointing in two different directions.

All that said, I can't understand why Science published this paper. Nothing that I said above is new, and while you can always retest the basic principles of quantum mechanics, I don't see what they could expect 80+ years into the game with an accuracy of only 1% (!). I've only read the abstract, though. -- BenRG (talk) 23:56, 25 July 2010 (UTC)

Question about effects of lightning

Why doesn't people's hair stand on end, or some sort of effect on other things similar, before a nearby lightning strike? If lightning were to strike, wouldn't that mean that there is a bunch of negative charges in the clouds, thus attracting a bunch of positive charges together in the ground? I would think that with the amount of charge required to create dielectric breakdown given the large distances involved, such an effect would be noticable? 68.160.243.61 (talk) 20:36, 25 July 2010 (UTC)

"Why doesn't people's hair stand on end..." It does.. I've experienced it. Try to avoid getting that close to a lightning strike.. 83.100.252.126 (talk) 20:40, 25 July 2010 (UTC)

If you feel your hair stand up, then the safest thing to do is kneel, and tuck your head between your legs. --The High Fin Sperm Whale 21:01, 25 July 2010 (UTC)

Just remind me, what is it that you're then supposed to kiss goodbye? 87.81.230.195 (talk) 21:40, 25 July 2010 (UTC)

Despite the similarity to a joke, it is actually good advice. Spikes (which a person standing on the ground is) tend to concentrate charge, making them likely targets for lightning strikes. Since your backside is quite round, it's a good idea to stick it in the air. --Tango (talk) 21:51, 25 July 2010 (UTC)

Why not lay flat? APL (talk) 21:03, 26 July 2010 (UTC)

When lightning hits a tree or the ground, there is a strong potential gradient around the spot, such that two points several feet apart may have several thousands of volts between them during the strike. If your head and your feet touch the ground 6 feet apart, more current will flow through your body than if the only ground contact is your feet a few inches apart. A contortionist who could form a low ball balanced on one foot might fare better yet. Edison (talk) 04:38, 27 July 2010 (UTC)

Pix or it didn't happen, I'm willing to accept a do over Nil Einne (talk) 21:03, 25 July 2010 (UTC) More seriously I found a picture [11] Nil Einne (talk) 21:06, 25 July 2010 (UTC)

You might also see Positive streamers coming up from the ground around you, I can't find a good picture of one but we have an article on it.83.100.252.126 (talk) 21:16, 25 July 2010 (UTC)

St Elmo's Fire is another fun effect that can occur right before a lightning strike. APL (talk) 21:26, 25 July 2010 (UTC)

Does St. Elmo's fire really occur before lightning strikes? I have never heard about that. --The High Fin Sperm Whale 01:43, 26 July 2010 (UTC)

again, personally experience, no proof - yes it does - I've seen it coming off bushes on tops of hills prior to a strike - it's not clear to me whether in this case "St. Elmo's Fire" and "Positive Streamers" are the same thing - I think they are.87.102.43.171 (talk) 13:58, 26 July 2010 (UTC)

How did Supersaurus avoid being hit by lightning? Count Iblis (talk) 02:02, 27 July 2010 (UTC)

There was a famous 1976 photo of hikers who thought it was funny that their hair was standing on end. Supposedly a lightning strike soon thereafter killed some of them [12]. Edison (talk) 04:45, 27 July 2010 (UTC)

Sealing in juices; frying meat

Hello! It is me again. =)

I desire a once-and-for-all answer on a topic I see is debated... namely sealing in juices in meat. Some authorities I've read state that it is simply not so that juices stop escaping, backing this up with claims about experiments showing no difference when pieces of meat are cooked one way or the other, by measuring their weight, ie no juice escaping. Others say they do, once you've created an impenetrable crust on the outside of the meat, that is through searing/caramelization. If I fry a piece of meat, is it in fact juicier by cooking correctly in this manner? Thank you in advance. 88.90.16.109 (talk) 23:12, 25 July 2010 (UTC)

If published authorities say different things, why do you imagine you can get a once-and-for-all answer from the anonymous non-experts who answer questions on Wikipedia? Looie496 (talk) 00:34, 26 July 2010 (UTC)

A lot of cookery shows and cook books show that the experts all seem to do this. If the experimental evidence is that the meat doesn't weigh any different cooked one way or the other - then all that says is that the REASON that doing this improves the final product may not be what is claimed. Perhaps, for example, the juices leave the meat later in the cooking process if it's 'seared' first - the final weight would be the same - but the ability of the liquid to keep the temperatures lower for a little longer before they boil away might be enough to change the flavor or texture. The chemistry involved in cooking and flavor are stupendously complex...this is not a simple thing to analyze. So it's very possible that the science isn't there yet. But for sure simply cooking the same exact cut of meat using two different techniques and then weighing the final product is a pathetic experimental test to prove whether searing the meat is or is not a good idea. SteveBaker (talk) 01:50, 26 July 2010 (UTC)

Searing does not "seal in juices". Searing is a good technique, but for a completely different reason. John Riemann Soong (talk) 02:41, 26 July 2010 (UTC)

However, cauterization does stop bleeding. It's not the same thing, of course (unless the rest of the cow is still attached to the steak) but there may be some effect of searing on how fast the "juices" escape the steak. --Dr Dima (talk) 02:54, 26 July 2010 (UTC)

Try this experiment: make two identical weight hamburgers. Leave one with an uneven (porous) surface with nooks and crannys, and make the other one with a very smooth surface with almost like a coating of meat goo. Then cook the two the same. The one with the smooth surface will be substantially more juicy. —Preceding unsigned comment added by 165.212.189.187 (talk) 12:53, 26 July 2010 (UTC)

That's not actually an experiment which is just about 'sealing' the surface, though. First, the uneven surface with nooks and crannies will have a significantly greater surface area; even if there was no difference in the rate at which moisture escapes through seared versus unseared surfaces, the uneven burger would lose moisture faster because of its greater exposed surface. Second, the cooking of the 'rough' burger will be less uniform. Small exposed bits of meat on the surface (which will have a very high surface area in proportion to their volume) will dry out rapidly and may even char. These dry, crunchy bits are apt to have a disproportionate effect on the perceived moistness and doneness of the meat — particularly when the experimenter is looking for a particular result.

Doing a proper, controlled experiment – instead of just looking for an outcome to confirm a particular chef's biases, which often is the preferred outcome – is actually pretty challenging. It might go something like this. 1) Obtain a large amount of ground beef; mix until fairly uniform throughout. (Each burger should have the same fat and protein content.) 2) Prepare burgers of standard shape (using some sort of mould or press) from equal masses of meat per patty. 3) Cook burgers using an assortment of time-temperature profiles to desired degree of doneness. 4) Weigh the burgers after cooking to determine mass loss during cooking. (Incidentally, I strongly suspect that just these experiments have been done, if someone familiar with the food sciences literature knew how to search for them...?)

Note that there is wiggle room in step 3 — how should you determine doneness? I suspect that you'll be able to get two different results, depending on your methodology here. If you use a measure of internal temperature to determine when the meat is cooked, I suspect that you'll find searing has an advantage. It's not because searing 'seals in juices'; it's just because that quick pulse of high heat up front means that you will be able to employ a shorter overall cooking time. On the other hand, if you sear one batch of patties and not the other, and then cook for the same duration over medium-low heat, the unseared patties will be moistest. All that said, of course, proper searing will almost always greatly improve the flavor of the final product, and deserves to be done for that reason alone. TenOfAllTrades(talk) 14:01, 26 July 2010 (UTC)

That's all very well - but this isn't anything to do with burgers - they are so full of holes, you couldn't hope to 'seal' all of the surface area anyway! The technique is for solid cuts of meat - steaks, that kind of thing. SteveBaker (talk) 14:09, 26 July 2010 (UTC)

Agreed - by the time meat is ground, I don't think any culinary expert talks about "searing" it. Searing only really applies to solid meats. Nimur (talk) 16:38, 26 July 2010 (UTC)

On Food and Cooking says that "searing for sealing" doesn't work, and that's good enough for me. --Sean 14:13, 26 July 2010 (UTC)

Searing meat actually causes you to lose more juice, not retain it. See here. Good ol' Alton. Matt Deres (talk) 15:02, 26 July 2010 (UTC)

OP here. Thank you for all your answers, some of which were exceptionally informative. In particular TotoBaggins', which I must admit had me rather credulous. I am not hesitant to ask for more evidence that searing seals no juices (which I shall get that book, right certainly), but I'll understand if the minds here concerned with cooking have been exhausted on this subject. Until anything else, I will not speak of sealing the juices when I fry my beefs (which there was never a question of doing or not doing in a pan! Oh no, for the outwards effect we -must- have), but I shall not educate others until an example of the aforementioned book has come into my hand, and I can lecture them the very details. Well, perhaps I am not entirely honest. I will surely tell them to not think of the juices. 88.90.16.109 (talk) 23:32, 26 July 2010 (UTC)

What you want to trap juices is to denature the proteins in such a way that they "trap" the juices within their structure. Which is why I use kosher salt...it also lowers cooking time somewhat. You can sear to caramelise then turn the heat down low to complete the cooking since some of the denaturation has been done for you. See Jaden's very enlightening article "Steak: How to Turn Cheap “Choice” Steak into Gucci “Prime” Steak". John Riemann Soong (talk) 00:03, 27 July 2010 (UTC)

Has nobody linked the searing article yet? -- BenRG (talk) 01:53, 27 July 2010 (UTC)

Ok you're right Its not an experiment - its a fact that the smoother burger is more juicy! But, hello, what I'm trying to say is that if the meat is prepared properly searing does, in fact, seal in the juices, if the meat is not prepared properly then it does not! —Preceding unsigned comment added by 165.212.189.187 (talk) 13:57, 27 July 2010 (UTC)

No, that's completely incorrect. Here is the transcript of a show where a professionally trained chef performed the experiment with at least a modicum of scientific rigour and came to the exact opposite conclusion - searing meat causes it to lose more juice. Our searing says the same thing with an independent reference. Matt Deres (talk) 17:26, 27 July 2010 (UTC)

Juices sealed or not sealed, the justification for searing is that it makes meat taste good. Any chef worth his salt will tell you this. The followup question is now, "how can meat taste good if it has less juices?" I think the answer is obvious - any "juices" in meat are mostly water. What flavorful components of meat are water-soluble and would "leave" the meat if any juices leaked out? Nimur (talk) 20:15, 27 July 2010 (UTC)

I'm having trouble finding a ref about flavorful compounds, but this site lists some water-soluble nutrients (mostly B vitamins) that would logically be reduced with the loss of water. This paper looks promising, though I'm not familiar enough with the terminology used to be sure. In any case, nobody is claiming that searing doesn't increase flavour or improve mouth feel. Matt Deres (talk) 21:43, 27 July 2010 (UTC)

I think I remember reading something, perhaps Readers Digest a long while back where they had some semi-scientific cook or something who showed what's said above, i.e. it make the meat lose more of its juices, he suggested the juices which come out cook (and I guess adhere to the surface) & help to give the meat flavour IIRC. Nil Einne (talk) 22:08, 27 July 2010 (UTC)

Hey Matt, you obviously never did what I suggested! why don't you try it and I'm sure I'll make you eat your non-juicy words. It's not necessarily searing that I'm talking about its the preparation of the meat that creates the juicier burger. Do you want juicier meat create some type of coating like a thin brushing of egg or what I alluded to earlier with burgers, handle it so that meat goo forms a layer on the burger. Also, Nimur, "juices" are not all water or they would call it water. Meat juices are emulsions and have oils and protiens and acids, blood is not water.