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August 22

A New Life Beginning at Fertilization

Is the statement that a new life begins at fertilization (also known as conception) a "soft" scientific fact, rather than a "hard" scientific fact? The reason that I'm asking this question is because I have an intelligent (overall, not necessarily on this topic) friend who said that life beginning at fertilization is a soft scientific fact, since the definition of life is based on scientists' opinions rather than on any universal truth. This is in contrast to, say, the Earth orbiting the Sun, which is a hard scientific fact since there is absolutely no disputes about it and it is based on universal truths rather than on opinions. My question is--is my friend right or not, and if not, why not? Futurist110 (talk) 02:51, 22 August 2012 (UTC)

Life began at some unknown event a little less than 4 billion years ago or so. Everything else is continuation of that event. --Jayron32 02:57, 22 August 2012 (UTC)

I meant a new life. Sorry for the confusion. Futurist110 (talk) 03:02, 22 August 2012 (UTC)

Now you have to define "new". Someguy1221 (talk) 03:05, 22 August 2012 (UTC)

And you have to define "a". The problem is, there are lots of events, and lots of slow processes which lack a single event, along the path of life, where by an individual "organism" is said to be progressing towards its own independence. If it were that simple, we wouldn't have the controversy. The point is, the only reasonable event where one could say there was a definite start was the original moment of abiogenesis. After that, there are not any convenient single moments in time, nailed to the exact second, which differentiates you as an individual from that initial event. Conceptually, "birth" and "conception" mark the two most convient, for the simple minded, but only because they seem to be nice, simple events. But as moments, they aren't necessarily all that advantageous for defining a "start" since anything which would grant them that primacy seems trivial once you get into the processes. Why is birth special? A newborn infant would die if left unattended after birth, and a child delivered before natural birth (either by caesarean or induced labor) can be cared for and raised to an adult. So why birth? And why conception? There are similar problems with making that moment special. Any reasoned argument that attempts to nail down that "moment" can be presented with similarly reasoned and reasonable arguments to the contrary. The real answer is that the only answer is political: there is no agreed "scientific" definition which will satisfy the need to define when a human being becomes an individual being, and when it isn't. So, you're going to need to find your guidance elsewhere. --Jayron32 03:38, 22 August 2012 (UTC)

Note in particularly saying a new life begins at conception is problematic because monozygotic siblings come after conception, so your 'a new life' can become two or more new lifes. Ultimately as Jayron32 and BenRG said, this isn't a scientific question. Nil Einne (talk) 04:06, 22 August 2012 (UTC)

Conception is a good mark in the sense of defining as to when a new human development process begins, since human development generally goes from conception (or when a zygote is split into twins, etc.) to death. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

But there is no conception without ejaculation. So why is conception more important than ejaculation. And there is no ejaculation without that person having being conceived, and then you get a recursive set of events back to the moment of creation. Conception is not an event without its own causes and precedents, so there isn't anything particularly "first" about it. --Jayron32 04:38, 22 August 2012 (UTC)

WP:EC (Assuming I understand the spirit of your question...) Whether or not a definition of life is a matter of opinion is, in itself, somewhat of a matter of opinion. See Life#Definitions, which says "It is a challenge for scientists and philosophers to define life in unequivocal terms.", and gives three references. A counter argument to "life begins at conception" could revolve around whether or not a zygote meets all the criteria for life. You do not specify human life per se, but often these sorts of questions come up in the context of human reproduction. A related, but much more difficult question is then, if a zygote is alive, is it a human? Harder yet: is it a person? By nature, these questions are not purely scientific in nature, and must perforce be answered in the context of some philosophical, political, and/or legal framework. Needless to say, the answers to these questions are the subject of much discussion and dispute. SemanticMantis (talk) 03:06, 22 August 2012 (UTC)

(ec) I don't believe many scientists argue that an embryo isn't alive. However, for setting abortion policy and such, other questions come up, like at what point the embryo becomes viable, outside the womb. There you will get a range of answers. StuRat (talk) 03:08, 22 August 2012 (UTC)

I am aware of the difference between life and personhood. The fetus becomes viable at about 21.5 weeks or so right now (with current technology), which is a hard fact. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Sperm are alive too. Conception means the death of a sperm. HiLo48 (talk) 03:19, 22 August 2012 (UTC)

Sperm are a part of your body. They have your DNA and are not a whole entity passing through any stage of human development, unlike a zygote. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Interesting perspective. The question didn't explicitly ask about human life. HiLo48 (talk) 07:45, 22 August 2012 (UTC)

Futurist110, apparently you slipped when you said that "the Sun orbiting the Earth" ... "is a hard scientific fact". [I need to use your username for clarity, because the previous comment is not indented.]

—Wavelength (talk) 03:25, 22 August 2012 (UTC)

(now indented)

If object A is orbiting object B, it also means that object B is orbiting object A. Ergo the Sun is indeed orbiting the Earth. A8875 (talk) 03:57, 22 August 2012 (UTC)

Also not true. The Earth does not orbit the Sun, nor does the Sun orbit the Earth. The two orbit a common barycenter. Insofar as barycenter of the earth-sun system is located within the sun itself, it is more correct to say the Earth orbits the Sun than the other way around, but the scrupulously correct answer is that they orbit their common barycenter. --Jayron32 04:15, 22 August 2012 (UTC)

Sorry. That was obviously a typo on my part. I obviously meant "the Earth (and the other seven planets) orbiting the Sun". Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Even if the barycenter is outside both object A and object B people still use the word "orbit". In vernacular speech "orbit" pretty much applies to all circular and elliptical movements, regardless of where barycenter is. This usage is not scientifically correct as you pointed out, but it's what people uses. A8875 (talk) 04:29, 22 August 2012 (UTC)

Your real question is when a new human life begins. That isn't a scientific question at all, "hard" or "soft". It's a question of definition or, at best, of ethics. The only scientific answer is Jayron's. -- BenRG (talk) 03:42, 22 August 2012 (UTC)

Is there an impartial, objective (non-biased) definition to life, though? My friend says that even if all scientists agree on one definition, that this definition of life isn't objective and that there is no objective definition to life. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Scientific definitions of "life" are usually objective, in that they consist of a set of criteria that can be judged objectively; any system that meets the criteria is defined as being alive. There is no unified scientific definition of life (different groups use different definitions) and the definitions don't always correspond with common non-scientific definitions, but that doesn't make those definitions non-objective. --Carnildo (talk) 00:51, 23 August 2012 (UTC)

Like others mentioned above, the definition of when a life begins is mostly a philosophical and a political one. Since definitions are tautologies (by definition), they are not subject to the scientific process. Definitions cannot be "wrong", but they can be counter-productive. For example if the Sanctity of Life Act passes, it would mean that 27% to 37%[1] of new-born US residents die in the womb, bring the average life expectancy down to the low 50s, behind Kenya, Congo, and Niger. A8875 (talk) 04:17, 22 August 2012 (UTC)

Yes, but by the new standards of this law, all other countries' life expectancies would significantly decrease as well, while life expectancy since birth (the traditional measure) would still stay the same in the U.S. and everywhere else. Futurist110 (talk) 04:25, 22 August 2012 (UTC)

Precisely. It would necessitate the concurrent usage of two definitions, and two separate life expectancy rates in pretty much all birth related international documents and discussions. Hence "counter-productive". Thank God WP's country infobox doesn't have life expectancy on there.A8875 (talk) 04:34, 22 August 2012 (UTC)

It probably won't be that counterproductive considering that one would be able to calculate the new life expectancy very quickly. Futurist110 (talk) 04:38, 22 August 2012 (UTC)

It will still be a hassle though. Since each country publishes their own statistic based on their indigenous definitions, every time an American hears a birth or life expectancy related statistic from another country, they have to perform the mental calculations. This is by no means a new problem. Cuba has higher infant mortality rate than US[2] because the definition of "infant mortality" differs between the two countries. Many people interpret this statistic erroneously by concluding that Cuba's universal healthcare is responsible (admittedly it's a minor contributor). A8875 (talk) 05:36, 22 August 2012 (UTC)

• Speaking of "a" life is problematic at any time, even for adults. Consider split-brain experiments. Life is not really designed to be counted in this manner, as is particularly evident in some phyla such as siphonophores. In humans, every cell is potentially clonable, and thus potentially a life.

• Sperm and eggs are each arguably a haploid generation (gametophyte) and their union marks a diploid generation.

• The end of human life in the legalistic sense, as opposed to viable cells for culture, is defined in terms of brain death. The brain death criteria might also be applied to fetuses to define the beginning of life.

• As I recall, neurotransmitters start up around 6-7 weeks, forerunner neurons around 10, and others around 12 weeks. These time intervals are not dissimilar from comments about quickening by Aristotle and Saint Augustine (I think it was) at 40 to 80 days after conception, which presumably are based on a subjective sense of when an aborted fetus appears alive. (After all, they had abortions back then) However, authorities have long maintained that the "higher" ability to sense pain awaits the 8th month of gestation or so. (I'm not going to look up cites for all this stuff because it's not the question asked).

Bottom line: not a hard scientific fact. You might as well ask how many pieces of yellow there are in a lemon. Wnt (talk) 04:51, 22 August 2012 (UTC)

As others have said, the concept of "life" as it is being used here, is an ethical question more than it is a scientific one. At best science can inform some of those moral opinions. Conception gets thrown around as some sort of brightline quite a bit, but whether or not the science backs that up is questionable. An enormous number of fertilized eggs are lost without the woman ever knowing it. Historically there have been a wide variety of determinations about when "life" begins, including conception, quickening, birth, and even after that. In a very strict legal sense, personhood has been understood as birth in the U.S. for example. There are laws that make the death of a fetus criminal, whether it's abortion or something else, but that doesn't mean the fetus is considered a person. From a strict legal standpoint, birth is a clear brightline. Shadowjams (talk) 05:08, 22 August 2012 (UTC)

Just because a lot of fertilized eggs are lost naturally doesn't mean that they weren't alive. Those historical definitions were generally based on the knowledge back then, not on the knowledge now. For instance, in the pre-industrial era many people thought that life only began once the fetus began to move (quickening, as you say), whereas we now know that this is not the case. The legal sense isn't very practical when it comes to these matters, as the law can and often does change and since the law is currently inconsistent (if the woman wants the offspring, then the offspring is a person, if not, than the offspring is not a person). Futurist110 (talk) 05:14, 22 August 2012 (UTC)

My point in mentioning the number of lost fertilized eggs is simply to suggest that conception isn't a defacto brightline moment; you could choose others including implantation, quickening, third-trimester, sentience, birth, etc. Shadowjams (talk) 05:41, 22 August 2012 (UTC)

The question we're all skirting around here is "So what?" The usual goal of defining when life starts is to justify one's policy position in the abortion debate, as though the first should lead unambiguously to the last, but that isn't necessarily so. In no other policy decision is the "scientific definition of life and its start" used to provide a rationale for the taking of (or for the preservation of) life, whatever your working definition is. If we really want to get down to it, human societies since time immemorial have never really had any universal principles which preserved all human life in all cases. Every society has defined situations when the taking of a human life (either through self defense, war, capital punishment, or whatnot) is allowable. So even conceding that it may be possible to define the "start of life" (not admitting that one can, merely conceding to make the next point), it doesn't mean squat when trying to decide where one stands on the abortion debate. There is no universal principle, it is merely a weighing of competing interests, and reasonable people will value those interests differently. People who place values on one side of the scale end up as "pro-life" and others, with different values, end up as "pro-choice", but it doesn't mean that either position is based more than the other on "sound science". Neither is, fundementally. That's why the debate is intractable: it ultimately comes down to individual conscience, and in matters of conscience, it is possible for reasonable people to arrive at different conclusions. --Jayron32 05:23, 22 August 2012 (UTC)

For the record, I wasn't trying to say or imply that one acknowledging life beginning at conception as equivalent to saying that abortion is wrong and/or morally unjustifiable. The abortion debate has a lot of other factors at play other than when life begins. I was simply wanting to know the validity and accuracy of my friend's statement. Futurist110 (talk) 05:38, 22 August 2012 (UTC)

As Shadowjams says succinctly above, there isn't a magic moment, however. Conception is as good as any other moment, which is to say that it isn't better than them either. You're friend's statement isn't even wrong, as the saying goes. --Jayron32 05:46, 22 August 2012 (UTC)

As I said above, we do use brain death to make decisions, i.e. we evaluate the "scientific definition of life and its end" based on the belief that neural signalling is required for "life", even though obviously many other organs of the body remain alive after brain death. The zygote is one more type of cell that is not a neuron. Wnt (talk) 12:30, 22 August 2012 (UTC)

True, but we also use other events to decide when a person is worthy of death; i.e. when they are a soldier in the army of another country, or when they have committed certain crimes, or have certain diseases, or any of a number of other criteria, that have little to do with definitions of "life" and its milestones. No society has ever, as a culture, taken the step that all human life in all forms is to be preserved at all costs, and no society that has decided that some lifes aren't worth protecting (or that some lifes are worth ending) has ever based those decisions on such purely on such milestones. Thus, even conceding that there are some milestones in a life which are worth taking special note of, it doesn't directly follow that policy needs be based solely (or even primarily) on those milestones. It comes down to subjective value on individual lives, and on qualities relating to those lives, and reasonable people will disagree about subjective value. --Jayron32 12:41, 22 August 2012 (UTC)

Well, it sounds like you're saying that by allowing those who have suffered brain death to die completely, that we are making a decision to perform euthanasia. I suppose that is a position you can take, but I think that most people making that decision do so out of the genuine belief that those in that situation are not meaningfully alive, rather than out of a belief that their lives aren't worth protecting. Wnt (talk) 12:56, 22 August 2012 (UTC)

Well, that's because you define "meaningfully alive" to exclude a certain group of people. If we have differing definitions of what it means to be "meaningfully alive", then we have differing definitions over what value to place on what bits of living tissue. That's the crux of the problem. Human society has for millenia redifined humanity to make killing and other inhumane acts ethically tolerable. Without making any judgement (for the sake of this discussion) which definitions of "really human" and "meaningfully alive" and any of a number of other concepts, people generally agree that "really alive, really human people" are accorded certain rights, but if we don't all have the same definition of what those terms mean, then we have conflict. Again, I'm not saying whether or not your criteria for "brain death" is the correct one to choose when making decisions about what it means to be alive, rather I am saying that no particular choice is entirely incontrovertable: there is no single choice where every single person will reasonably agree with you. That doesn't mean you aren't right, it just means that you aren't going to be free from conflict or controversy, and that any particular choice about your criteria is going to be so self-evident as to be agreeable to all people. --Jayron32 14:29, 22 August 2012 (UTC)

Not to beat a dead horse here (oh wow that's a bad pun...) but Jayron's point is particularly acute given your example of brain death. It's only relatively recently (past few decades) that brain death rather than cardiac death has been the relevant standard in terms of law and medicine. The most obvious consequence being the wider (although still too small) availability of organ transplants. Shadowjams (talk) 17:07, 22 August 2012 (UTC)

Reference Needed for Multiplicity (psychology)

Does any psychologist recognize this and have good source for it? It is risking to be deleted. Thanks.Wikipedia:Articles_for_deletion/Multiplicity_(psychology)#Multiplicity_.28psychology.29 -- RexRowan  Talk  18:11, 22 August 2012 (UTC)

WP:CANVASS might be relevant to posting about an ongoing AFD. Edison (talk) 19:07, 22 August 2012 (UTC)

Thank you for pointing it out for me. I have looked for reference on the psychology project. -- RexRowan  Talk  19:12, 22 August 2012 (UTC)

srface charge density on a sphere

Let's say you know the potential at every point on the surface of a sphere. How then do you find the surface charge density? --150.203.114.14 (talk) 15:17, 22 August 2012 (UTC)

Does the article charge density help you figure that out? It looks like it involves some simple calculus to solve. --Jayron32 15:21, 22 August 2012 (UTC)

I see no equation relating charge density to potential. --150.203.114.14 (talk) 15:29, 22 August 2012 (UTC)

That equation would be Gauss's law... which can be stated as an integral, or formulated into an inversion-problem so that you can determine the charge distribution, given the potential. In nontrivial cases, the inverse problem may be underconstrained. In realistic physical situations, complicated potentials are unlikely, as a conducting sphere will relax to an equipotential surface after some period of time. So: to directly answer your question: given, potential as a field, to solve for charge distribution we invert Gauss's law, making suitable approximations that match our physical expectations. Depending on those assumptions, and the condition of the potential field, the mathematical methods could simply be direct solution of a simple algebraic formula, or may require very detailed machinations. Nimur (talk) 16:01, 22 August 2012 (UTC)

Double tolerance problem article ?

Do we have one ? Perhaps under another name ? (I suppose this is a special case of tolerance stack up.)

The problem, in short, is that two mating parts (lets say a jar and a lid) normally fit fine, but when the jar is at the wide end of it's tolerance and the lid at the narrow end of the tolerance, they don't fit. This could either be a result of the design tolerances being too generous, or the items exceeding those tolerances. (I suspect that manufacturers will accept a certain degree of this problem, as avoiding it by tightening up on tolerances can be more expensive than the occasional pair that don't fit together.)

The result is that most lids fit most jars, but occasionally a certain combo won't work. Tellingly, if either a different jar or lid is swapped in, then they usually fit again.

If we don't have an article, I'd like to create one, so would like any other names for this and examples you can think of.

There's some mention of it here. 203.27.72.5 (talk) 20:57, 22 August 2012 (UTC)

can't break speed of sound?

I've heard that in the 1920s, 30s, or 40s, scientists thought that an airplane could not break the speed of sound. I googled and couldn't find anything. Did scientists really think that? Did some think that? Is it an urban legend? Bubba73 ^{You talkin' to me?} 21:33, 22 August 2012 (UTC)

Early planes that approached the sound barrier when diving often crashed due to the (by their standards) extreme forces. At the time, these problems were believed to be insurmountable. See note 2. 203.27.72.5 (talk) 21:49, 22 August 2012 (UTC)

Supersonic airplanes do need quite a few differences in design, to fly properly, like swept back wings, a long, narrow fuselage, etc. So, when trying to fly a plane not designed for such speeds over the speed of sound, it may indeed crash. StuRat (talk) 22:01, 22 August 2012 (UTC)

A major breakthrough was the discovery that in the transonic phase an effect called Mach tuck occurs, in which shock waves build up on the lifting surfaces causing the nose to plunge downwards. This was discovered by the team working on the Miles M.52 project during WWII. They devised the "all-moving tail" or Stabilator to overcome this, which is now universal on all supersonic aircraft. Sadly, before the project was cancelled, the Bell Aircraft company was given access to the drawings and research on the M.52, but the U.S. reneged on the agreement and no data was forthcoming in return." The Bell X-1 took all the credit, complete with British designed tail. Alansplodge (talk) 22:16, 22 August 2012 (UTC)

I'm not sure that scientists thought there was a real barrier there, but tabloid media enjoyed playing up that word. A bit like the four minute mile. HiLo48 (talk) 08:45, 23 August 2012 (UTC)

I don't think that you are correct HiLo; there are a number of effects on an aircraft as it enters the supersonic stage - in the 1940s these caused the loss of control or destruction of aircraft not designed to cope with these. See the sorry tale of Britain's first supersonic jet, the de Havilland DH 108, which killed the company's owner / test pilot before the problems could be ironed out. The four minute mile was just a case of running a bit faster than anybody else had. Alansplodge (talk) 17:01, 23 August 2012 (UTC)

Ok, I take some of that back; I have just found This NASA article; "The myth of the sound barrier had its beginning in 1935, when the British aerodynamicist W. F. Hilton was explaining to a newsman about some of the high-speed experiments he was conducting at the National Physical Laboratory. Pointing to a plot of airfoil drag, Hilton said: "See how the resistance of a wing shoots up like a barrier against higher speed as we approach the speed of sound." The next morning, the leading British newspapers were misrepresenting Hilton's comment by referring to "the sound barrier." The idea of a physical barrier to flight —that airplanes could never fly faster than the speed of sound— became widespread among the public. Furthermore, even though most engineers knew differently, they still had uncertainty in just how much the drag would increase in the transonic regime, and given the low thrust levels of airplane powerplants at that time, the speed of sound certainly loomed as a tremendous mountain to climb." Alansplodge (talk) 17:36, 23 August 2012 (UTC)

Thank you very much for finding that! Bubba73 ^{You talkin' to me?} 18:46, 23 August 2012 (UTC)

Or, we could quote from what was actually written by scientists about the subject at that time, "For various reasons it is fairly certain that the maximum attainable speed under self-propelled conditions will be that of sound in air"[3]. 203.27.72.5 (talk) 22:52, 23 August 2012 (UTC)

Thanks for that too. Bubba73 ^{You talkin' to me?} 01:50, 24 August 2012 (UTC)

Using fuel to cool an internal combustion engine

Jet engines commonly use the fuel to cool the area around the engine. Could the same approach work on an internal combustion engine, in conjunction with air cooling, or is the amount of fuel burned just insufficient for this ? (In the case of a gasoline engine, the gasoline could boil in the engine block, to cool it, and the fumes would then be burnt inside the cylinders.) StuRat (talk) 22:36, 22 August 2012 (UTC)

The specific heat - based thermal capacity, and the latent heat of vaporistion, does have a cooling effect on any IC engine (you obviously mean a piston engine here - an aircraft "jet" engine is also an internal combustion engine), but the effect is not that strong, and how/where it does it, depending on the type of engine, is not so obvious perhaps to a lay person as it may be for a turbine ("jet"). In a turbine, the design specifically involves having relatively cool areas (including cooled by fuel) and relatively hot areas (the downstreem combustion area) for properties of materials reasons. In piston engines, cooling happen, but the design aims are different.

In a diesel egine, fuel is injected into the combustion chamber at ignition time, in liquid form at a temperature below the air temperature at that time. Therefore, the fuel provides a cooling effect from its thermal capacity, and by absorbing latent heat of vaporisation as it is vaporised in order for combustion to occur.

In a diesel engine, the cooling effect of the fuel is undesirable, as it lowers combustion temperature and thus lowers gas expansion and thermodynamic efficiency.

In a gasoline engine, the fuel still has a cooling effect, but how it does it is a little less obvious. In a carburettor engine, evaporation in the carburettor casues the intake charge to be cooled, so combustion has a lower temperature to start from.

It should be realised that in a typical aircraft "jet" engine, thermodynamic efficiency is not that high, and gas velocities are high. These two reasons mean that cooling of combustion chamber walls is important. In practical pistion engines, efficiency is high and gas velocities low, so cooling of combustion chamber walls is not critical - typically only about 6% of combustion heat is lost via the combustion chamber surfaces. Ratbone124.178.39.239 (talk) —Preceding undated comment added 23:21, 22 August 2012 (UTC)

(ec)It would be extremely dangerous. In the air, if you get a leak it has plenty of air to dilute the fuel air mixture. In your car, you don't have that dilution in your engine bay, and the battery and other components provide ample opportunity for a spark. The high pressures of boiling fuel is going to make a leak all the more likely. I can't find any information on any attempts to do this or even suggestions that it could be done. 203.27.72.5 (talk) 23:25, 22 August 2012 (UTC)

Would it be any more dangerous than a CNG vehicle ? StuRat (talk)

Yes, very much so. Has your radiatior ever leaked? Now imagine hot pressurized gasoline is squirting out into the engine bay instead of radiator fluid. At least the natural gas isn't that hot if you get a leak, and there's much less chance to get a leak compared to a pressurized jacket around the engine. Plus the way cars are engineered to crumple when in a crash, doesn't require the engine to be protected. For most front engine cars, if they had this system of cooling they'd just about be certain to explode in a head on collision. The gas tanks on the other hand are in the rear of the car and engineered to rupture outwards. 203.27.72.5 (talk) 02:16, 23 August 2012 (UTC)

Not correct - see below. Ratbone124.182.134.244 (talk) 02:41, 23 August 2012 (UTC)

Perhaps it could, but why would it? Both diesel and petrol engines are usually cooled with a water jacket, occasionally by air; air's available in large quantities for free and water's not that much more expensive (given the cost of introducing water channels into an engine, anti-freeze and so on), so what would the advantage be of using fuel to cool an engine? Tonywalton ^Talk 00:26, 23 August 2012 (UTC)

Poster 203.27.72.5 is misinformed about practical engines. Having fuel in the crankcase is not especially dangerous. In loop-induction 2-stroke engines (as is common in small engines e.g. lawnmowers, some motorbikes), the fuel passes through the crankcase before entering the cylinder - this is because such engines cannot have useful cylinder suction - carnkcase suction as the piston goes up draws the fuel and air mix in, and then as the piston goes down, forces the fuel/air mix into the cylinder. Secondly, in 4-stroke engines, some fuel does leak past the piston and rings and get into the crankcase, especially as the engine accumulates wear. This does pose an explosion risk, and in small engines is managed by suitable venting. In large engines, as in large diesel engines used in power stations and marine propulsion, special pressure relief valves (biccari valves) are provided to allow crankcase combustion gasses to vent safely to atmosphere. In the early days on IC engine marine propulsion, crankcase explosions and consequent ship loss did occur until the problem and solution was understood.

As I explained above, the fuel DOES provide some cooling, either directly when injected, or indirectly by cooling the charge air. As it cools the engine anyway, it is unnecessary to pass it thru the crankcase for that purpose. Passing it through the crankcase, cooling-wise, will not achieve anything - heat removed from teh crankcase would be returned to the cylinder.

Passing fuel through the crankcase would be undesirable in a 4-stroke engine as it would pick up lubricating oil, causing increased oil consumption, cylinder & exhaust glugging, and bad emissions. These problems do not arise in an aircraft "jet" engine.

Ratbone124.182.134.244 (talk) 02:15, 23 August 2012 (UTC)

Just to be clear, I'm not saying that small amounts of fuel in the engine bay are going to cause an explosion. I'm saying that hot gasoline could leak out in large quantities due to the pressure of boiling it (as suggested by StuRat) and the resulting fuel air mixture would be very explosive. Diesel wouldn't be such a worry due to it's much lower vapour pressure. My comments were about modern 4-stroke petrol engines used in cars. 203.27.72.5 (talk) 02:24, 23 August 2012 (UTC)

Ok, but consider these facts: Firstly, it takes no great pressure to boil/vaporise gasoline. In carburettor engines, it's done in the carburettor at atmospheric pressure. In fuel injected gasoline engines, its doen in the intake manifold, at less than atmospheric pressure. In loop induction 2-strokes, the fuel/air mix is first sucked into the crankcase, and then compressed, not as much as in the cylinder, but it is to 2 or so atmospheres. Thse engines are very common, and leakage is just not an issue. Lastly, somewhat off-track, explosion of diesel in crancases sunk ships until (100 years ago) they learnt to put in relief valves. It is a mistake to think diesel is safer in this regard. Ratbone124.182.134.244 (talk) 02:41, 23 August 2012 (UTC)

I don't think you see what I'm saying. It's not that a great pressure is required to boil gasoline, it's that boiling gasoline will greatly increase the pressure in a sealed jacket around the engine (i.e. constant volume). If that pressure is released because of a leak, that fuel will vapourize more or less instantly and fill the engine bay, causing an explosion hazard. 203.27.72.5 (talk) 02:47, 23 August 2012 (UTC)

It need not raise the pressure though. It does not in conventional carburettor and injected gasoline engines. One could arrange for fuel vaporisation in a crankcase or other chamber at a near constant pressure or a controlled pressure rise. It's just pointless, cooling-wise, to do, that's all. Ratbone124.182.134.244 (talk) 03:03, 23 August 2012 (UTC)

The understanding I have of StuRat's question is basically, could you have an engine that is cooled by pumping fuel into a jacket around it, and as it vapourizes from the heat given off by the engine, inject it into the cylinders? Maybe that's not really what he meant, but I assumed it is. Now, as you've pointed out, you would need more fuel to vapourize for cooling the engine than you would need as fuel to burn, so there's that problem with this idea. My comments were based on the assumption that to stop so much fuel from vapourising, you would have to allow the hot fuel to pressurise in the jacket. True enough, you could instead pump far more fuel as coolant around the jacket than what actually gets consumed and return it to the fuel tank. But that's not really any different to a conventional radiator system, so there's no savings in terms of efficiency there. 203.27.72.5 (talk) 03:21, 23 August 2012 (UTC)

Ah, now I see what you were getting at. You have it all pretty right, I think - expecially your last sentence. If you circulated fuel around, the tank would become the radiator - its radiant equivalent volume, and the air stream would have to be much the same as a normal radiator & fan system. However, the specific heat of fuel is a about 30 to 40% of that for typical water+glycol mixes, so the engine would require a bigger coolant jacket, and need to run a bigger coolant pump. That will increase weight quite significantly. In car engines, cylinders are oftem "siamesed". You might not be able to do that using fuel as coolant, so the block will need to be longer. Ratbone124.182.134.244 (talk) 03:44, 23 August 2012 (UTC)

Yes, you're right about the difference in specific heats, I didn't take that into account. Anyways, glad we got there in the end. I was already thinking of how I was going to draw a diagram using ASCII :D. 203.27.72.5 (talk) 04:25, 23 August 2012 (UTC)

The object would be to reduce vehicle weight by eliminating the radiator, coolant, auxiliary coolant tank, coolant hoses, etc. Drag could also be reduced since you wouldn't need air to ram the radiator to cool it. The result should be improved fuel efficiency. Since air-cooled engines do work, but only for small (low compression ?) engines, hopefully this would allow it be used in beefier engines. StuRat (talk) 01:57, 23 August 2012 (UTC)

Just for your interest, air-cooling is not limitted to small sizes. Until rendered obsolete by turbojets, air-cooled aircraft piston engines were made up to megawatt sizes - the Wright Cyclone (up to 2.76 MW) and the equivalent Pratt & Witney being the most famous. Aircooling does not limit compression ratio - in any case a higher compression ratio gives greater thermodynamic efficiency, reducing cooling requirements. Ratbone124.182.134.244 (talk) 03:58, 23 August 2012 (UTC)

Well, aircraft are a bit different, as air is available at higher velocities to use for cooling, except for when idling on the ground (I wonder if this makes them overheat). StuRat (talk) 04:42, 23 August 2012 (UTC)

True - then there is the flat-4 volkswagen engine - 1600 cc, very sizeable compared to a lawnmower, and can be hotted up to deliver as much power as any 1600 cc engine. They had a well known tendency to overheat in Australia, but that does not negate aircoooling. It was just a consequence of being designed in Germany, which has a much colder climate. Some owners here added extra outboard scoops that increased airflow - they cope with our climate just fine then. Ratbone124.182.179.59 (talk) 05:59, 23 August 2012 (UTC)

I wonder if using the gasoline to pre-cool the engine would be a viable alternative to those air scoops (which must increase drag and reduce fuel efficiency). StuRat (talk) 07:15, 23 August 2012 (UTC)

I doubt it. Give it away Stu. The scoops would increase drag, but it is a matter of proportion. Going purely on my memory (almost all flat-4 VW's are worn out now, you hardly ever see one) the scoops usually had a frontal area of about 150 x 300 mm, one on each side. That's very much larger than the factory standard air intakes but is only about 2% of the vehicle frontal area, so I doubt it would be possible to measure the increased drag. Gasoline cooling could only amount to roughly 2% of engine non-exhaust heat output, as explained elsewhere. A more important consideration is that the scoops violate current Australian design rules aimed at eliminating side projections (door handles/locks must be flush for example). If a VW factory standard passes an inattentive pedestrian within 100 mm at (say) 30 km/hr, the pedestrian will only get a fright, or perhaps severe bruising if he makes contact. A VW fitted with the scoops will take the pedestrian's head off, killing instantly. Ratbone124.182.179.59 (talk) 08:10, 23 August 2012 (UTC)

I bet the drag is more than an additional 2%. That's what you would get with a nice rounded lump. The turbulence created by a scoop is far worse. StuRat (talk) 08:37, 23 August 2012 (UTC)

It could well be. And could well be less. I've seen very professional looking rounded scoops, and also very rough square box types obviously home made. We should, for the purpose of this discussion assume a reasonably professional low turbulence design. I only meant to show you the rough scale of it. You'd need a much larger increase for it to be measurable, and very much larger for a typical owner to notice it in fuel consumption. Ratbone124.182.179.59 (talk) 09:02, 23 August 2012 (UTC)

80 H.P. Le Rhône 9C rotary engine - and yes the whole lot rotates

See Rotary engine for a solution to that: fix the crankshaft to the engine bulkhead and have the pistons and cylinders (and attached propeller) rotate around it! AndyTheGrump (talk) 04:57, 23 August 2012 (UTC)

That seems nuts. Doesn't the gyroscopic effect make it difficult to turn the plane ? StuRat (talk) 05:42, 23 August 2012 (UTC)

Such engines were the norm with World War 1 aircraft. They were popular due to certain simplifications enabling high power (for the day) with light weight. Yes, the gyroscopic effect does make it harder to turn in one direction, but easier to turn in the other direction. There are 2 factors that sort of mitigate it: Firstly, aircraft back then were biplanes with low wing loading, low speeds, and big control surfaces. Secondly, you get a lot of gyroscopic effect from the propellor anyway. The prop may not be as heavier, but its much larger in diameter, and the gyro effect is proportional to the square of the radius. Single propellor aircraft with any real power (i.e., not your user friendly but underpowered Cesna) are well known for handling vices due to propellor gyroing. Look up takeoff procedure for the British Spitfire, and US military evaluation of captured Japanese Zero fighters for clear examples. Ratbone124.182.179.59 (talk) 06:13, 23 August 2012 (UTC)

Cooling of aircooled radial engines on the ground doesn't seem to have been a problem. Even the non-cylinder rotating types get airflow from the prop. Typical operating instructions for WW2-vintage types werr to start and warm up the engine(s) with the cooling flaps (they are the flat projections you see just behind the cowl) closed, and open them for take-off, or opne them when the temperature gauge gets past x-many degrees. See http://www.zenoswarbirdvideos.com/main.html for a fascinating collection of old US military training films that show this. Ratbone124.182.179.59 (talk) 07:52, 23 August 2012 (UTC)

The cooling effect of fuel, in the quantities used for combustion, is far too small to enable any noticeable reduction in radiator size, etc. In a typical 4-stroke, say a 15 litre diesel truck engine al la Cat C15 producing 276 kW at 1500 RPM, cooling from injected fuel amounts to around 5 kW, whereas the total heat rejected to coolant is 202 kW. You may be confusing the total cooling requirement for a piston engine (of roughly the same order as its power output) with the relatively small part of the aircraft jet engine cooled by fuel. Ratbone124.182.134.244 (talk) 02:31, 23 August 2012 (UTC)

Yes, that sounds insufficient to cool such a big diesel engine, but how about a more modest gasoline engine, say a 3, 4, 5 or 6 cylinder ? StuRat (talk) 04:45, 23 August 2012 (UTC)

Stu, obviously, all the heats go up or down more or less in proportion to the engine power. I don't have data for any small three-cylinder engines, but taking the Daihatsu 3-cyl gasoline car engine as an example (800 cc or thereabouts, bore & stroke 69 x 70 mm, reasonable assumptions about bearing sizes, valve train, head configuration etc) a computer engine simulation tool I have predicts the following at 4000 RPM: Brake power output 28.2 kW, heat lost to exhaust 39.3 kW, heat rejected to coolant 27.1 kW, coolant effect of fuel ~~0.7 kW. The program is known to be within 2% for large diesel engines and is not optimised for small gasoline engines, but these figures will be reasonably close. The coolant effect of the fuel is substantially higher in this case than you would expect by scaling down from the C15 Caterpillar engine I quoted earlier, but this is only because the Daihatsu, as a gasoline engine, is a lot less efficient, so burns more fuel. The cooling effect of the fuel is never the less still too small to affect radiator sizing. I assumed a compression ratio of 9.5:1 as any higher resulted in the software predicting detonation, and it would take too much time to find out the actual detonation-affecting parameters. Ratbone124.182.179.59 (talk) 07:00, 23 August 2012 (UTC)

Thanks. How does air cooling fit into the equation ? Of course, cooling fins and such play a part, but there's also a surface area to volume ratio effect, where lawn mower engines are just fine with air cooling, but it's rather iffy for even small car engines. I'm hoping that the gasoline cooling might be just enough to make it a bit more practical to air cool a small gasoline engine. StuRat (talk) 07:12, 23 August 2012 (UTC)

Stu, you're not paying attention. Air-cooling car engines is completely viable - flat-4 VW's being just a not particularly well executed example. They were originally designed down to the cheapeast possible price on Hitler's instructions. A historically important reason for air-cooling not catching on is the noise. Cylinder cooling fins are effective at transfering mechanical noise to the air. Water cooling pretty much damps it out. Historically, air cooling made for higher engine wear, higher fuel consumption, and poor emissions, due to dificulty in maintaining a constant engine temperature. Water cooled engines incorporate a thermostatically controlled valve in the coolant circuit, and regulate their temperature quite precisely. With modern electronically controlled servo motors, it would be quite possible to regulate engine temperature almost as well with air cooling though (it can't be quite as good, as the heat has to get from the combustion chambers thru the fins and into the air. In a water cooled engine the heat has a short direct path into the water, which has a specific heat 1000 times better than air.) Have you not stood next to an idling air-cooled Volkswagen and heard the dreadful noise it makes? The radiator fan in a water cooled car engine absorbs power at low speeds, but it's not much, and a VW engine has a fan too.

Regardless of air cooling or "water" cooling, the amount of heat to be got rid of is the same, about one third of the combustion heat. So fuel cooling, as a "helper", is no more viable for air cooling than it is for water cooling. The fuel is ALREADY cooling the engine anyway, as explained, not withsatnding the consideration that some of the recovered heat will end up going out the exhaust. Engines of the lawnmower sort are less efficient than car engines - this means that more fuel cooling is available, but there's more heat to get rid off, and it doesn't change the viability. If you wish, I can calculate heats for a couple of small lawnmower-size engines I have comprehensive data for, thoough it won't be accurate. Ratbone124.182.179.59 (talk) 08:31, 23 August 2012 (UTC)

So you're saying a large air-cooled car engine is possible, but would just be too noisy ? How about using active noise control ? StuRat (talk) 08:41, 23 August 2012 (UTC)

You've GOT to be joking!!! Noise is of course in the ear of the beholder - witness Harley Davidson motorbikes. I did include the word "historically". I can think of ways of installing sound damping baffles, but they did not think of that back then. It would add cost and considerable volume to the car though. There may be other ways. Ratbone124.182.179.59 (talk) 08:49, 23 August 2012 (UTC)

Please humor me and explain why active noise control won't work here. StuRat (talk) 19:44, 23 August 2012 (UTC)

He's not saying it won't work. It's wholey impractical though. Most jurisdictions have noise pollution laws, so it's not just a matter of the driver wearing noice cancelling head phones. And on the point of air cooled car engines, here's another example; Porsche used air cooling in all of the 911 models up until 1998. 203.27.72.5 (talk) 20:33, 23 August 2012 (UTC)

So how did they handle the noise problem ? StuRat (talk) 02:33, 24 August 2012 (UTC)

Who would want to drive a Porsche that didn't make noise? I mean, besides the guys who made this thing. 203.27.72.5 (talk) 06:35, 24 August 2012 (UTC)

If you increase the noise level from an old VW beetle in proportion to the power increase in a Porsche 911, it would be too loud to be street legal, wouldn't it ? How do they prevent this ? StuRat (talk) 20:40, 24 August 2012 (UTC)

I don't know anything about Porsche 911's - they are a rare vehicle here in Australia. And I have no idea what the noise regulations are in Stu's USA. I do know that 911's are 6-cylinder whereas the VW is 4-cylinder. Just on this you would expect the 911 to be 50% louder arithmetically, i.e., an increase of 1.8 dB. As the human ear has a logarithic perception, this is pretty minor. The minimum discernable sound increase is 1 dB. For a perception of twice as loud, 10 dB, 10 times the sound power, is needed. VW's are cheap rubbish are built down to a minium price, but Porsche is an expensive brand - this may have allowed Porche to do some sound engineering (double meaning pun intended). At least in Australia, with regard to vehicle noise, the focus has been politically driven - politicians and police have reacted to young men hotting up their cars, and driving in an obnoxious manner. Hence the focus is not on a rational total noise level basis. The police never react to motorbikes ridden by older men, and some bikes, factory standard, are extremely noisy. But a teenager, driving an ordinary car, showing his friends what it can do by accelerating flat out in first gear gets pulled over and charged for excessive noise every time, regadless of how quite or noisy the car actually is. Is it the same in the USA? Ratbone58.170.164.33 (talk) 01:28, 25 August 2012 (UTC)

Yes, although they tend to pick on anyone who "doesn't fit in" rather than just the young. If you are to wrong race, or poor in a rich area, you will be pulled over for the most minor of offenses. I was the victim once. While in college, on a tight budget, I drove a rusted out 1973 Mercury Marquis. I was once in a situation where some idiot was trying to make a left on a street with no left turn lane, and only one lane in each direction, in the middle of rush hour, creating grid lock. I, along with everyone else behind him, quite sensibly pulled around him on the shoulder. The cop ticketed me for driving on the shoulder, and let everyone in more respectable cars go. StuRat (talk) 02:06, 25 August 2012 (UTC)

While I wouldn't say that they are common, Porsche 911s aren't what you'd call rare over in Brisbane. I've seen the Porsche club line both sides of entire streets with them when they meet. Another Important thing to note is that the VW beetle was designed by Ferdinand Porsche who also designed the Porsche 356, which later evolved into the 911. All of these cars are German engineered, rear engined and air cooled, so they're more similar than a cursory glance might indicate. 203.27.72.5 (talk) 06:49, 25 August 2012 (UTC)

I think the bit about lining a street is a) not impressive, and b) perhaps misleading. Brisbane and Perth where I am are pretty similar. You only see a Porsche 911 on the roads maybe once every few months, but you see Fords, Holdens, & Toyotas literally every minute. I see carreras every second day or so - even that rate means it is pretty unusual. I have a friend who owns an MG TC. When their club meets, they fill streets with TA/TC/TD's too. Nobody would they they aren't rare. There's no doubt though that the VW "beetle" and the 911-style Porsche cars are at least superficially similar - but that doesn't stop the VW being junk. I'm not saying the Porsche is junk - I'm not in a position to know. I do know about beetles and Combis - a company I worked for for many years had a fleet of both of them. They were worse than Morris Mariners to drive, scary, and had the shortest engine life of anything - sometimes failing catastrophicly within 2 years or even less. It is well known that the beetle originated in a car designed to Hitler's requirements - which were essentially "make it as absolutely cheap and nasty as posible, so the peasants can buy them, while we Masters can ride around in our big chauffeur-driven Mercedes." It was the same concept as the 3-tube VolksRadio - another Hitler-era piece of junk just able to pick up the local Nazi station. At that time German electronic engineering was the best in the World, but that VolksRadio was just weird junk. Ratbone60.230.234.239 (talk) 11:07, 25 August 2012 (UTC)

I think you're being a bit harsh with the VW Beetle. Yes, it's a basic economy car, but any model that lasts some half century after it's introduction definitely had something going for it. Tall people liked them because of the domed roof, which meant they actually had headroom, versus other econoboxes. I seem to recall another quirk, that the windshield wiper fluid was squirted out by using pressure from the spare tire, as opposed to a little pump. As long as you remember to add air to the spare tire every time you gas up, this seems like a good way to reduce complexity. StuRat (talk) 19:39, 25 August 2012 (UTC)

The VW is in this regard like the British Morris Minor. Both were kept in production for years without much change, for as long it could be sold, and for as long as they still passed Govt safety requirements. The VW is an extreme example of this. It contrasts with the American manufacturer practice of a 3 year model cycle. It must be noted that while American-owned car manufacturers have seen to it that the cars look different every 3 years or so, mechanically they hardly ever changed. For example, 6 cylinder cars made in Australia by Holden (Holden is a local car maker owned by GM), they used the exact same Stronberg BV2 carby, and the same diff from 1948 to 1979, only two different engines (the "grey" and the "red"), only 2 different auto transmisions, etc etc. VW's were truely awful. Not only did the engines have a short life as I said, the controls were an ergonomic disaster (for instance the pedals hinged from below, unlike every other car since the 1920's). The procedure to change gear during acceleration in any manual car is as follows: We are in first, now its time to change up. Put in clutch quickly & take foot off go pedal, move stiff gear lever from "1" to "2", let out clutch smoothly while pressing go pedal. Procedure in flat-4 Volkswagen: We are in 1st, now it's time to change up. Put in clutch quickly & take foot off go pedal. Pull gear lever out of "1". Now, waggle the bendy gear lever around where "2" should be, until you feel a slight click. Gently let the clutch out a bit to find out what gear it is - shit, it's 4th. Press clutch back down, pull bendy lever out of 4th, waggle it round again until click. Seems like that's the same spot as before, oh well, let the clutch out a bit. Ah, good, it is "2" this time. Engine lugs because the vehicle speed has dropped too much. That's part of why VW's could last a fair while in private use, but in company fleets they were very failure prone. An indication of how bad the VW Combis were is this: Until 1977, the only low cost boxy side-door delivery vans available in Australia were the VW Combi, and the Commer (itself almost as bad in its own way). There has always been a considerable commerical need for such vans, and so the Combi enjoyed big sales. There were things like the Ford Transit, but they were a much bigger & heavier vehicle, for which there is not so much need. In 1977, Toyota introduced the first "Hi-Ace" van. Combi sales evaporated virtually overnight, and VW Australia withdrew it from sale. In a similar way the Ford Escort displaced the fleet market for VW beetles and Morris Minors. Ratbone124.178.177.224 (talk) 01:26, 26 August 2012 (UTC)

How can you insult a car that was exported from Aussie in one of your pop songs ? Although, come to think of it, it was a "fried out Kombi" and the song implied that people who drive them must be drunk, on drugs, or both... :-) StuRat (talk) 02:30, 26 August 2012 (UTC)

Well, as another, somewhat less subjective measure of the relative frequency of Porsche cars in Australia, have a look at carsguide.com.au. Currently, there are 458 Porsches for sale, compared to 73 M.G.s, 675 Land Rovers, 311 Daihatsus, 390 Daewoos, 24,616 Toyotas. I'm not suggesting that they're common, but you definitely encounter them on a pretty regular basis, especially if your route takes you through some of the nicer suburbs. 203.27.72.5 (talk) 20:35, 25 August 2012 (UTC)

You can't be serious! Assuming for the moment that the number for sale is proportional to the number registered for road use, and not significnatly affected by durability, owner satisfaction, etc, that's 0.019 Porches, of any sort, for every Toyota of any sort. Sounds like a rare car to me. Only a small part of those 458 Porches will be the 911's we were talking about - as I said you see Carreras quite often. You can see your data is dubious by the figure for Daewoos - they are certainly far more common than Porsche. You left out data for Fords, Holdens, & Nissans. It would be reasonable that compared to all four major brands of long standaing (Toyota, Ford, Holden, Nissan), you'd get Porsche 911 at less than 0.002 911's per car of any brand & type. Ratbone124.178.177.224 (talk) 01:26, 26 August 2012 (UTC)

It's not meant to be the be all and end all of measures. It's just meant to be better than "well I think I see them lots when I drive around". I'm not sure what you're talking about when you say "Carreras", which are almost all 911 Carreras (all Porsches were rear engined and air cooled prior to 1998 except for the unpopular 924s, 928s and 944s anyway). The reason I stuck in Daewoos (I just chose a sampling from the 50-100 brands listed) was to illustrate that it's approximately similar to the number of Porsches, so they have similar rarities. Given that Daewoos badged as such were only made between 1982 and 2011, and Porsche 911s have been made since 1963 and always badged as such (with the tiny exception of RUF), and their higher value and quality makes them worth maintaining for decades after production, it's not inconcievable that they'd number about the same as Daewoos. 203.27.72.5 (talk) 03:27, 26 August 2012 (UTC)

Can the OP give a particular reference as to where what components jet engines use fuel for cooling? Rockets are jet propulsion engines but normally they use the liquid O2 for cooling.. MW 50 (alcohol and water mixture) was used to boost the power of German bombers, and a similar system for US Tomahawks by cooling the intake air. Military gas-turbines similarly, often use just water injection to cool the intake air during compression in order to boost power but it reduces the life of the power plant -so is little used for normal operations.--Aspro (talk) 00:54, 23 August 2012 (UTC)

Maybe this isn't as common as I thought. Precooled jet engine mentions the concept of cooling the intake air using the fuel, but apparently this isn't in production yet. StuRat (talk) 01:52, 23 August 2012 (UTC)

It depends on how you define what you mean by useing fuel to cool the engine I guess. Precooling is about cooling the fuel before it enters the engine, a totally diffrent concept to using the thermal capacity (specific and latent) of the fuel to help manage temperatures in an engine. Ever since Wittle and others introduced jet engines for aircraft, jet engine design engineers have specifically calculated on the basis of using fuel thermal capacity to keep parts of an engine at temperatures low enough metallurgically. I had thought that that was what you were refering to. I hope you caught the basic points I made ealier - 1) fuel consumption is relavtively high in a jet, so the usable fuel cooling effect is larger, 2) it only cools part of a jet combustion system, and 3) combustion chamber wall cooling is more critical in a jet than in a piston engine. Ratbone124.182.134.244 (talk) 02:52, 23 August 2012 (UTC)

Actually, precooling in the article StuRat linked to above is about cooling the air going into the jet engine (using the fuel as the coolant), not cooling the fuel. 203.27.72.5 (talk) 03:00, 23 August 2012 (UTC)

Darn it! You are right. I should have read the article Stu linked, before posting, instead of going on my memory of what I read in a text book. Ratbone124.182.134.244 (talk) 03:09, 23 August 2012 (UTC)

Also, as far as it being a wash because the cooling of the engine block is made up by the heating of the fuel, wouldn't most of that heat end up going out the exhaust, after combustion, rather than going back into the engine block ? StuRat (talk) 04:50, 23 August 2012 (UTC)

In a modern gasoline engine, roughly speaking, of all the combustion heat, one third gets turned into mechanical effort on the piston, one third ends up via various paths heating the coolant, and one third is lost as waste heat in the exhaust gasses. So, roughly speaking, you could expect the recovered heat to also split equally the three ways. I should have thought of that, though for reasons discused by myself and 203.27.72.5, the amount of heat that can be recovered by combustion quantity fuel is necessarily too small to matter. Ratbone124.182.179.59 (talk) 06:34, 23 August 2012 (UTC)

Don't think anyone has so far mentioned our article on internal combustion engine cooling, have they ? Gandalf61 (talk) 08:43, 23 August 2012 (UTC)

Stu's smart enough to have already read that. As a long time committed Wiki man, I expect he already read it and didn't get what he wanted. He doesn't need us to tell him it's there. As a general rule, I assume that OP's asked their question because they did get what they needed from Wikipedia. In any case many articles are not exactly good quality. Ratbone124.182.179.59 (talk) 08:56, 23 August 2012 (UTC)

From his statement of the question he already seemed to understand how a radiator works, so I don't see what he would have gleaned from that article. 203.27.72.5 (talk) 20:39, 23 August 2012 (UTC)

There's another interesting aspect to this fuel cooling / pre-cooling /fuel efficiency business, that I should have thought of before. It was common up to the late 1970's for car engines to have a water-jacketted intake manifold or "hot box". The hot box heated the intake air, and the reason thay did it is that it improved fuel economy slightly (minor reason), and it hastened engine warmup (strong reason) as the water flowed in the manifold jacket even when the therostat blocked off radiator flow. It is thermodymamically the same as passing the charge thru the crankcase, and so in that sense StuRat's idea has been in use. It was dropped in the late 1970's when car manufacturers had to meet tight emission standards. After then, they heated the intake air by passing part of it through a cover on the exhaust header. A servo-controlled vacuum powered motor moves a baffle to vary the percentage of intake air moving over the exhaust, to regulate the intake air temperature faster and more accurately than is possible with a water jacketted manifold. Altough the prime purpose is to ensure precise combustion conditions and low emissions, it will improve fuel consumption. So, in a sense, StuRat's idea is still in use.

In modern diesel engines, turbo-charging is almost universally used, in order to stuff more air in and increase power output. It also significantly improves fuel ecomony as it recovers some exhaust heat and puts it to use. Because compressing air increases its temperature, which reduces density, a turbo on its own has limitted effectiveness. To fix that, and intercooler is used. The intercooler uses radiator coolant to cool the intake air, increasing its density and thereby increasing power output. Well, that's what it does when the engine is heavily loaded. At light loads, the turbo doesn't spin very fast, and doesn't heat the air. The intercooler becomes an interheater, improving part-throttle economy.

Still with me, Stu? Ratbone120.145.40.59 (talk) 23:14, 23 August 2012 (UTC)

Yes, the turbo lag is why superchargers are sometimes used. StuRat (talk) 02:33, 24 August 2012 (UTC)

Actually, Stu, superchargers have long since ceased to be used, except for special cases that have nothing to do with avoiding turbo lag. Superchargers are low tech - no special materials required. Turbos had to wait for development of high temperature materials. Reasons for supercharger decline in use: (1) a turbo, by utilising eshaust heat otherwise wasted, improves fuel efficiency, whereas a supercharger, by taking mechanical power from the crankshaft, while it can increase power output, reduces fuel efficiency. (2) A turbo is cheaper. (3) thermodynamically, except for taking power from the shaft, a supercharger is much the same as increasing the compression ratio & swept volume - it's simpler to just build an engine with increased swept volume and compression ratio.

Superchargers get used when: (a) a vintage car enthusiast want to hot up his relic and wants to do they way it would have been when the vehicle was current. (b) a manufacturer is loosing sales because a competitor has introduced a bigger engine, and the afore mentioned firm need to do something quick and cheap; (c) the engine is a uniflow 2-stroke, which cannot itself suck air in. (although it is common with uniflow 2-strokes that the blower is driven electrically, and not from the crankshaft); (d) high altitude aircraft piston engines.

Turbo lag can, in most applications be made acceptably short by: (1) using two or more small turbos in parallel, insterad of one big one - this method is very common; (2) using a larger turbo in conjuction with a waste gate - this is reasonably common. Waste gating is simple, cheap, and can, if desired, completely eliminate turbo lag. (3) Using a camshaft that opens the exhaust valves early. This gives more exhaust energy and shortens the response time, and doesn't reduce efficiency very much, and you can get that back with just a bit more turbo boost. This method is not common, but is gaining ground. Ratbone120.145.168.86 (talk) 11:26, 24 August 2012 (UTC)

OK, thanks all. StuRat (talk) 08:36, 25 August 2012 (UTC)

Resolved

August 23

Breast size and milk production

Do both correlate in female humans? OsmanRF34 (talk) 00:09, 23 August 2012 (UTC)

Only in that breasts do swell during lactation. StuRat (talk) 00:11, 23 August 2012 (UTC)

Yes, but if small breast have less potential for swelling, then, a woman with small breast will produce less milk? That might not be that important if maternal milk substitutes are available, although across evolution it could have been relevant. OsmanRF34 (talk) 00:24, 23 August 2012 (UTC)

Surely they must correlate, isn't it obvious? I saw a doco on breast feeding recently and one lady was shown with quite ample breasts who had to express every day even more then her child could drink to get the swelling down, she had litres and litres of the stuff in her freezer, that is just an anecdote and very well could have been a special case, but I don't believe it was presented as such. As to what kind of source you could find to support it, beats me! Vespine (talk) 01:32, 23 August 2012 (UTC)

Huh huh you said "support" —Tamfang (talk) 00:05, 25 August 2012 (UTC)

Interesting, it might actually not be as simple as that, if you google do big boobs make more milk you'll find some interesting reading. I'm not going to google that at work but I did on my phone and it appears, from a cursory browse, that in fact milk production might not correlate with big boobs, but big boobs certainly can HOLD more milk. Vespine (talk) 02:00, 23 August 2012 (UTC)

Breast size is mainly determined by the amount of fat, not by the amount of milk gland. As you would expect, there would have been strong evolutionary pressure to ensure that almost all females to have enough milk galnd tissue to support a baby, but the fat is just there to protect the glands from impact from falls, and make them attractive to males. An indication of how small the milk glands are when not feeding occurs when females get breast cancer. These days, for stage 1 (ie not yet spread to lymph nodes) cancer, treatment is to surgically remove all gland tissue and a 1 cm margin of tissue around the lump. This happened to my daughter in law and she went down just one bra size. As milk glands only occupy a small part of the breast, you would expect little or no correlation of mik capacity with breast size. Ratbone124.182.134.244 (talk) 03:24, 23 August 2012 (UTC)

The great apes do just fine breastfeeding their offspring. Human breast and penis size is a result of sexual selection. μηδείς (talk) 03:36, 23 August 2012 (UTC)

What's curious to me is that no one seems to care. There are some quality studies on the correlation between milk production and the increase in breast size that occurs during pregnancy ([4] for example), but I'm finding precious little on the the relationship between raw size (pre- or post-pregnancy) and milk production. But what's most curious about this is that the data has certainly been collected, the researchers simply aren't discussing it, which implies they don't find the data interesting. Looking at some other sources around the internet, mostly self-published ones (although by physicians or pediatricians), seems to suggest that there is no correlation, provided you remove from your data set outliers on the size chart that are only there because they have a breast-related medical condition. Someguy1221 (talk) 03:38, 23 August 2012 (UTC)

I suspect that the reason for not studying it is that any scientist who wants to study breast size risks being thought of as a pervert (although, if it was for some important reason, like the risk of breast cancer, then maybe not). StuRat (talk) 04:54, 23 August 2012 (UTC)

I suspect the reason no one studies it is that most healthy females are not really constrained by how much milk they could produce. The milk production is determined by consumption and is capable of going much higher in the case of twins, triplets or even (bizarrely) an adult partner breast feeding. Of course malnourishment and other problems may limit production and perhaps correlate but the general principle is that it is not an issue. --BozMo talk 06:04, 23 August 2012 (UTC)

There are studies that have to do with breast size and inheritable tendencies toward certain types of cancer. I have only read of them in newspapers, so have no specific references, but do recall them quite clearly. One type of cancer ran in Jewish families. For pictures of how small ape breast are in breastfeeding mothers, see these pictures of gorillas and these pictures of chimps. μηδείς (talk) 03:52, 24 August 2012 (UTC)

I recall some vague reason for suspicion that feeding a pregnant mother milk from cows fed on linseed oil or safflowers could put a hex on her daughter's breast size and milk production, but I'm not finding strong evidence presently, but that might be because I'm snowed under here [5] and haven't looked carefully. (See conjugated linoleic acid, [6], [7] for background) Wnt (talk) 13:04, 25 August 2012 (UTC)

Airspeed

Why do pilots use airspeed instead of ground speed? Clover345 (talk) 10:40, 23 August 2012 (UTC)

Pilots need and use both. Ground speed is used for navigation purposes. Air speed is critical, because winds at flying altitudes are significant. For example, an airliner cruising at 10,000m has a cruising air speed typically 800 km/hr, has a stall speed in cruise configuration 700 to 750 km/hr, and will encounter tradewinds typicallly 200 km/hr. They need ground speed for navigation, but for safety and optimum fuel consumption air speed is what counts. Ratbone121.215.38.12 (talk) 11:26, 23 August 2012 (UTC)

Until the arrival of GPS technology there was no way to directly and accurately measure ground speed in the aircraft in real time - there is no "ground speedometer" in an aircraft instrument panel. Roger (talk) 12:29, 23 August 2012 (UTC)

Not true. I remember being invited to the flight deck of an airliner 40 years ago. The pilot showed me two things showing ground speed: a ground-speed indicator based on auto-correlation radar, and a Distance Measuring Equipment (DME) display, which was also counting off the miles to the next airport at 4-place accuracy like the odometer in a car. DME is based on special ground transmitters installed for the purpose. See http://en.wikipedia.org/wiki/Distance_measuring_equipment. In any case, a trained navigator can calculate ground speed from bearings and timings to purpose built radio beacons, radio and TV stations, planets, stars, etc. And there were all manner of radio navigation aids invented in World War 2 and just after. The Germans had an effective radio navigation for accurately bombing English targets regardless of weather - well it was accutate until the Poms put up their own transmitters on the same frequencies to confuse the Germans. It's just that the technology of the day required large expensive equipment, unlike your cheap hand held GPS. Ratbone121.215.38.12 (talk) 12:55, 23 August 2012 (UTC)

It is true that long-range airliners, business jets and military aircraft have, for several decades, had equipment that provides the pilot(s) with an accurate indication of ground speed. The great majority of aircraft are smaller, simpler general aviation aircraft and, until the advent of low-cost GNSS equipment, they didn't have access to equipment providing an accurate indication of ground speed. More importantly, they didn't need it, and they don't really need it now. When flying under the Visual Flight Rules the only use for ground speed is as an aid to navigation - but who cares if the pilot arrives at his destination a few minutes before or after he originally calculated. Of much greater importance to the pilot of a general aviation aircaft is his airspeed in relation to the stalling speed, speed for best rate of climb, speed for best fuel consumption etc. These speeds are all airspeeds, not ground speeds. Dolphin (t) 13:18, 23 August 2012 (UTC)

Often when 'airspeed' is referred to, what is meant is indicated airspeed (IAS) - the speed as shown on the airspeed indicator, which only corresponds to true airspeed (TAS) under specific conditions. It is however the most useful measurement in regard to stall speed and other limiting speeds. See also V speeds, Equivalent airspeed and calibrated airspeed for more on the subject. AndyTheGrump (talk) 13:22, 23 August 2012 (UTC)

Why doesn't kilometers per hour have a special name?

I've noticed that there are several derived units have special names (like the Newton, Pascal, Joule, Ohm, Tesla, etc.), but why doesn't Kilometers per hour have one? Being one of the most commonly used units, it can be surprising that it does not have a special name unlike the other derived units. Narutolovehinata5 ^tccsdnew 12:05, 23 August 2012 (UTC)

If any speed unit had a special name, it would be metres per second would it not? It is usually the more complex derived units that have special names. Most people understand m/s (or km/h), but not many know what a (kg·m²)/(s²·A) is. Dbfirs 12:11, 23 August 2012 (UTC)

Knot (unit) would appear to be a special name for a speed? So would Mach. --BozMo talk 20:58, 23 August 2012 (UTC)

Both of those have special histories, though. Knots, if the story I've heard is correct, were measured by laying out knotted rope into the water and counting how fast they go past. And Mach number is not a measure of speed per se, but of speed relative to the local speed of sound, which is of importance for predicting the way air behaves as the craft passes through it. --Trovatore (talk) 21:25, 23 August 2012 (UTC)

Momentum has way more credence than speed. Plasmic Physics (talk) 12:30, 23 August 2012 (UTC)

Special names e.g., newtons, are good for scientists, engineers, and other boffins who use them on daily basis and can get used to them, and they are shorter than the full form, saving the boffins some writing. But for ordinary people, km/hr is a lot more informative, almost as short, & easier to use. Also, there is only one way to cite speed, distance per time, but the special name units generally have alternative ways: E.g, Tesla = V.s / m = N / A.m = Wb / m² = kg / C.s = kg / A.s = N.s/Cm . Some of these alternates make the meaning a bit obscure, so a special name helps. Ratbone121.215.38.12 (talk) 12:41, 23 August 2012 (UTC)

121.215 hits the name on the head. Any basic unit can always be reduced to a relation between core SI units, like meter, second, Ampere, and kilogram. Nearly all of our "named" units like Newtons or Joules or Henrys are quite complex in terms of reducability to core SI units (the Joule, for example, is kg*m²*s^-2 while the Henry is kg*m²*s^-2*A^-2. Also, the more complex the measurement, the more ways to express it, as Ratbone notes with the Tesla, I always think of the measurement of Energy, which commonly has units of the Joule (reducable to base SI units), the calorie (normalized to the specific heat of water), and the liter-atmosphere (used in many forms of the universal gas constant) as ones I use on a regular basis as a Chemistry teacher. With speed, I use only meters per second and kilometers per hour, both of which are simple enough to conceptualize for most people. For measurements which are reducable to two base units, there isn't a need to name them. --Jayron32 12:52, 23 August 2012 (UTC)

Jayron, feel free to call me Ratbone. Ratbone121.215.38.12 (talk) 13:05, 23 August 2012 (UTC)

Also note that "kilometers per hour" is a little bit long for some people who shorten it to "kilometers an hour", "kilometers", "clicks" or just omit the units all together as in, "Honestly officer, according to my speedo I was sitting on a hundred..." 203.27.72.5 (talk) 21:29, 23 August 2012 (UTC)

In the context where kilometres per hour are most frequently discussed, vehicle speeds, the "name" of the unit is simply omitted. For example, "I was doing about 95 when this idiot overtook me over double lines." All listeners know what the unmentioned units are. That's a pretty effective short cut. HiLo48 (talk) 17:17, 23 August 2012 (UTC)

With, of course, the caveat that even if "speed" is understood by all listeners (a supposition which may not be true, depending on context), the particular units are not so. — Lomn 17:43, 23 August 2012 (UTC)

Derived units are based on the SI base units (which are rooted in part in the MKS system of units), and neither kilometre nor hour are MKS. It effectively introduces a 1000⁄3600 (5⁄18) constant into the mix, making dimensional analysis as silly as if you were using imperial or U.S. customary units. Km/h is a consequence of legislation, and there's no compelling reason to give it an SI derived unit name. BigNate37_(T) 21:12, 23 August 2012 (UTC)

I was going to suggest calling them Volts after the Chevy Volt. Given that is already taken, how about calling them Slows? μηδείς (talk) 01:42, 24 August 2012 (UTC)

Which mobile standards uses OFDM?

Which standards for mobile phone communication HSDPA, HSPA+, 4G, etc. Makes use of OFDM ..? Most articles mentions line coding like 64QAM but doesn't mention if that's in a multi- or single carrier scheme. Electron9 (talk) 12:28, 23 August 2012 (UTC)

Our article mentions it is used in IEEE 802.20 (which appears to be dead), WiMAX and LTE. Do you have any reason to think it's used in the other standards or that it is otherwise incomplete? Nil Einne (talk) 14:00, 23 August 2012 (UTC)

The OFDM article only mentions "4G" which correspond to many different standards. It's like saying Television uses OFDM.. it's incomplete information. But I suspect various 3G standards like HSDPA also makes use of OFDM. 1G/2G is "OFDM free" however ;). Electron9 (talk)

Sorry but you're quite mistaken. I got all the information from the article as I suggested in my first post, which isn't surprising since I don't know much about the subject. And it has been there since long before you posted your message [8] [9]. Looking at the version from August 11, just before any of your edits, in fact Long Term Evolution is mentioned in 3 different places in the article (all 3 also mention the abbreviation LTE). WiMAX in 5 (3 of these also mention IEEE 802.16). IEEE 802.20 in 2 locations (both also mention MBWA), and as I said that's a dead standard. Excluding the external link, there's only one place where 4G is mentioned not in close proximity to the specific 4G standards in development that use OFDM, and that's in the intro. Since the intro doesn't mention any other specific standard which uses OFDM, it's entirely unresonable to expect it to mention any specific 4G standard in development (and 4G alone appears to be accurate since all current putative 4G standards, even as our article also mentions the dead UMB standard, plan to use OFDM). Given the number of standards that use it, it's unresonably generally to expect it to be in the intro anyway point blank. So while I'm sure the article is incomplete, it isn't as incomplete as you suggested, perhaps it is your reading that was incomplete. (Although I barely read the article myself and when composing my first reply IIRC I didn't even need to search yet still found the info.)

P.S. AFAIK, with the death of the UMB standard and the similar apparent death of 802.20, there's only two standards really competing to be 4G, LTE and WiMAX. Of course there may be extensions of 4G in the future which will be somewhat different standards, just as there was with 3G, but that seems way too far in the future to worry about, particularly since we're still a fairly long way from 4G.

P.P.S. I actually suspect you're mistaken on HSDPA as well. For starters our article strongly seems to imply OFDM is new to LTE etc when it comes to mobile communications. So do other sources. This one for example, [10] says things like

With LTE joining UMB and WiMAX in choosing OFDM as the underlying modulation technology, it could be argued that there is now little to choose between these cellular systems. Of the five major new cellular systems, only HSPA+ and EDGE Evolution do not use OFDM

(It's from 2008 so rather old but seems unlikely HSPA has changed that much.) Other sources like [11] say things like

According to sources, LTE is clearly the OFDM technology of choice for next-generation services; yet, HSPA is being driven to unleash tremendous wireless data throughput speeds. They anticipate that the majority of all operators who have deployed HSPA will upgrade to HSPA+ and will continue to enhance their networks through further evolutions for years to come, even as some may deploy LTE networks.

Of course as I said I don't know much about this, hence why I'm reluctant to definitely say HSPA etc don't use OFDM, there may be some subtleties on what the sources say when they refer to OFDM that I'm missing. Although my impression is it's just that it's not a simple matter combining OFDM with the needs of a mobile network so it wasn't used before now (and enhancements like HSPA couldn't change things too much), even if wifi etc were using it for a long time. Although I guess FLASH-OFDM and WiMAX have existed for a resonable while, albeit I believe real voice services for WiMAX only came fairly late and I'm not sure if they ever came for FLASH-OFDM.

Nil Einne (talk) 03:05, 24 August 2012 (UTC)

jerry sandusky

how did they charge jerry sandusky? didnt the statute of limitations expire? --Wrk678 (talk) 14:35, 23 August 2012 (UTC)

Welcome to Wikipedia's Science Reference Desk. This page exists to help Wikipedia editors locate and understand reference material related to scientific articles in our encyclopedia. If you need help locating an Internet forum for general discussion, there are many links in our article. Nimur (talk) 14:44, 23 August 2012 (UTC)

Our article on Jerry Sandusky contains much of what you're looking for (including the grand jury's indictment), and a Google search for "statute of limitations sandusky" fills in the rest nicely. Particularly, the statute of limitations for Sandusky's crimes stretched to at least 1994, though there was at least one other victim who missed the statute cutoff. I don't see a specific duration listed, but based on the dates, I'd assume the statute of limitations in this case is roughly 18 years. — Lomn 15:00, 23 August 2012 (UTC)

Its is also notable that some of his crimes he was convicted of were committed as recently as 2009, which is not that long ago. --Jayron32 16:36, 23 August 2012 (UTC)

how dou explain this then http://espn.go.com/college-football/story/_/id/7920784/charge-penn-state-administrators-likely-dropped-change-jerry-sandusky-shower-allegations — Preceding unsigned comment added by Wrk678 (talk • contribs) 16:33, 23 August 2012 (UTC)

That's a different crime with a different statute of limitations against different people. That article is about possible criminal charges against Penn State administrators who may have covered up the abuses of Sandusky. It appears that the statute of limitations on what those two administrators would be charged with is shorter than the statute of limitations for what Sandusky did. --Jayron32 16:38, 23 August 2012 (UTC)

Hydrogen at Fukushima Daiichi

Can anyone tell me if there were passive hydrogen eliminators at Fukushima Daiichi or just active ones that required electricity to operate? RJFJR (talk) 18:48, 23 August 2012 (UTC)

According to [12], the primary containment was purged with N₂ to prevent hydorgen ignition, and the secondary containment had no provisions for hydrogen mitigation at all, as scary as that sounds. That' backed up by [13] which says in the hydrogen mitigation section, "Fukushima Dai-ichi units were equipped to deal with hydrogen: the building containments were inerted with nitrogen and a venting system...other plant designs assume passive autocatalytic recombiners as technique to mitigate the hydrogen..." 203.27.72.5 (talk) 21:20, 23 August 2012 (UTC)

Bird call identification?

At about 9,000 feet elevation in the Rocky Mountains (Colorado), looking for a bird that has a call that sounds like a whining dog. In fact, it sounds very much like the whines heard at the very beginning of this youtube video. It's extremely loud and can be heard across the valley. We also have a Red-Tailed Hawk that does its usual screech, which lives in this valley, and sometimes when it screeches, I can hear the dog-whine bird (I assume it's a bird) kick up its vocals. So maybe it's a deterrent? But the whining happens without the hawk as well. I don't think it's a starling, and I've listened to ruffed grouse and hermit thrushes online and nothing sounds remotely like the dog whining in the video—despite what others online have suggested. Any ideas? It's a new call, haven't heard it in previous years. Thanks!Reflectionsinglass (talk) 20:53, 23 August 2012 (UTC)

Is it a screech owl? --Jayron32 03:16, 24 August 2012 (UTC)

What an interesting response! We do have a Western Screech-Owl, and for several years, we've heard him with the call heard here... the sort of tremolo oow-oow-woowoowoowoo, but he disappeared a month ago—I'm not here all year 'round, so I'm not sure the owl's habitat patterns. I've never heard this wheezing whining dog sound before... but just from the power of the voice, I wouldn't at all be surprised if it's an owl. I will look into it further. Thank you for the suggestion!Reflectionsinglass (talk) 04:30, 24 August 2012 (UTC)

There are several dozen varieties of screech owl, and each has a distinct call. If your Western Screech-Owl moved out, perhaps another species has recently moved in. --Jayron32 05:22, 24 August 2012 (UTC)

The other thought I had was a loon of some sort; loons are shockingly loud. I'm most familiar having grown up with common loons, which have a call that sounds like a woman being attacked. It's unnerving. Again, perhaps a species of loon? --Jayron32 05:25, 24 August 2012 (UTC)

I left out some details in my original query: the bird (again, I'm completely assuming this is what it is) sounds as if it is coming from the trees. (I guess I should ask, then—because I'm not familiar with them beyond picturing lakes in Vermont—are loons water-fowl only?) The bird was behind our house yesterday up in the evergreens/lodgepole pines, and today was on the other side of the valley, so I'm assuming he's a bird. He'll go quiet for lengthy periods of time, so I give up looking for him flying from one location to another. And one last detail, I only hear him call during the day or early morning. Not at night. /Reflectionsinglass (talk) 06:41, 24 August 2012 (UTC)

Looking for a second bird

I spent quite some time listening to raptors online this evening and simply cannot find this one either. I was biking at an elevation of about 10,000 feet, same location, mountains with coniferous pines or evergreens, and I kept hearing the call of a loud bird that I'm convinced is a raptor. It was a whistle, though. Not the screech of a hawk, not the weak pips of an eagle, more like the whistles of an osprey, though the osprey calls I've listened to aren't right. To help me remember what the call sounded like, I immediately compared it to the Sound of Music song, Do-Re-Mi, in the part where the children sing, "Do Mi-Mi..." The whistle had the same tonal steps between do and mi... and then the pattern was similar: one twothree. Dit dotdot. But a steady whistling, not wavering too much, and not dropping off like the osprey's. Again, any ideas would be fantastic. Thanks! /Reflectionsinglass (talk) 06:41, 24 August 2012 (UTC)

lichens: as decomposers

I have always understood that lichens are slow growing decomposers. This is really not mentioned in the article, except regarding minerals? Isn't it true? What do they eat, if not.They are described in the article as epiphytes.Are they epiphytes when they grow on trees, or decomposers? I have understood also that they were the first producers of soil on earth by decomposing minerals. The description of the historical age of lichens doesn't seem to bear this out. What is the truth as we know it? Thanks. — Preceding unsigned comment added by 24.168.44.14 (talk) 21:55, 23 August 2012 (UTC)

Lichens are weird critters. They consist of a symbiotic pairing of a plant and a fungus: they get their energy, like all plants, from the sun via photosynthesis, with the fungus portion subsisting off of material provided by the plant portion. The fungus portion, IIRC, digests the substrate (the stuff the lichen is growing on) to provide non-Carbon nutrients to the pair. --Jayron32 21:59, 23 August 2012 (UTC)

Gephyromantis VS Mantidactylus

Gephyromantis VS Mantidactylus

Recently, I have been creating Gephyromantis genus articles to only find out the genus page redirects to Mantidactylus. So I redirected all the pages I made to Mantidactylus. The problem is though that I don't know which is the right genus or why it redirects. I also don't know why Mantidactylus sources are under the name Gephyromantis on IUCN. Frwiki has both genus and all the species. Commons also has categories for the genus's. I am very confused, any help would be appreciated. Also Amphibians of Madagascar has both species (which is where I found Gephyromantis was all redlinks and started creating them). -- Cheers, Riley Huntley _talk No talkback needed; I'll temporarily watch here. 22:17, 23 August 2012 (UTC)

Blommersia, Boehmantis, Guibemantis, Spinomantis, Wakea (genus) also redirect to Mantidactylus -- Cheers, Riley Huntley _talk No talkback needed; I'll temporarily watch here. 22:31, 23 August 2012 (UTC)

As far as I can work out, Blommersia (Dubois, 1992), Boehmantis (Glaw & Vences, 2006), Gephyromantis (Methuen, 1920), Guibemantis (Dubois, 1992), Spinomantis (Dubois, 1992) and Wakea (Glaw & Vences, 2006) are synonyms of Mantidactylus. Thine Antique Pen (talk) 09:51, 24 August 2012 (UTC)

August 24

Brain and Lung Tumor?

Are there any types of cancer or other tumor-causing disease, perhaps zoonotic, in which one might get a single tumor in the brain and a single tumor in the lung, but not detectable anywhere else? I would have thought it rare that, say, lung cancer would metastasize to the brain. μηδείς (talk) 03:15, 24 August 2012 (UTC)

I don't think it's all that rare. Once a cancerous cell gets loose in the blood stream, it can then find it's way to just about any part of the body, and metastasize there. Body parts closer to the original tumor are a bit more likely, but most parts of the body are possible. StuRat (talk) 03:23, 24 August 2012 (UTC)

Brain is among the most common sites for metastasis of lung tumors. Proximity is important for spread by direct invation and via lymphatics, but once hematogenous spread (through the blood) occurs, proximity is unimportant. -- Scray (talk) 03:50, 24 August 2012 (UTC)

Really? I do know what metastasis is, and that the blood goes to the brain directly from the aortic arch. Is there anything specific I can read on lung cancer metastasis to the brain? I am especially curious if there are any other types of cancer and any other non-cancer diseases that act this way. μηδείς (talk) 03:58, 24 August 2012 (UTC)

Yes, pretty much anything that spreads via the blood can act this way, cancer or not. For a non-cancer disease, how about a blood clot ? They can form in one part of the body, dislodge, then cause a serious, potentially fatal, problem when they lodge in the brain. StuRat (talk) 05:02, 24 August 2012 (UTC)

No, that's not really accurate. Blood clots can form in the lungs OR the brain, and they can spread from other sites to the lung or the brain, but blood clots that form in the lungs do not travel to the brain. There are a variety of infections (e.g. bacterial, fungal) that can start in the lungs and spread to the brain. -- Scray (talk) 05:13, 24 August 2012 (UTC)

(ec) The abstract of this review PMID 21167939 highlights important aspects. The full text of this paper PMID 21487419 is freely available on Pubmed Central, with a nice illustration. -- Scray (talk) 05:10, 24 August 2012 (UTC) * μηδείς (talk) 06:02, 24 August 2012 (UTC)

Well, that's an effing scary abstract. Thanks. Still interested to know if there are worms or anything else that can result in just one brain and one lung tumor. μηδείς (talk) 05:25, 24 August 2012 (UTC)

Any organism that can cause a mass lesion/abscess in lung or brain could, theoretically, cause one of each at the same time. Examples include Strongyloides lung or brain abscess PMID 7055453, tuberculosis, and Nocardia, but there are many organisms that can do this; generally, though, it's not too hard to tell infection from tumor once you have good-quality imaging and an experienced doctor. Biopsy is often important to be sure. -- Scray (talk) 00:46, 25 August 2012 (UTC)

Higg's field and energy

Does the Higg's field have an energy density? Perhaps congruent with fermion mass densities? What was Einstein's view of the origin of fermion mass? Underpaidpresidents (talk) 16:48, 24 August 2012 (UTC)

The Higgs field ought to have a vacuum energy density (which would act like dark energy), and it ought I suppose to be negative given how the Higgs mechanism works. And it probably should be huge. What we actually find, though, is a tiny positive vacuum energy density. No one really understands vacuum energy.

I don't know if Einstein had any opinion about fermion mass. I think it wasn't an interesting problem until, at the earliest, the experimental discovery of parity violation in 1957. Einstein died in 1955. -- BenRG (talk) 16:59, 24 August 2012 (UTC)

A machine with free will

Is it possible to create a device which has free will?--130.56.71.53 (talk) 13:40, 24 August 2012 (UTC)

Define free will. Do you and I have free will? A computer will always function in the way it is programmed, even when programmed to reprogram itself. To really answer the question whether there is a fundamental difference between human and artificial decision making, we would have to understand what consciousness is and how we as humans make decisions. The answer will depend on your worldview, e.g. whether you believe in a soul, whether you ascribe to determinism, compatibilism etc. - Lindert (talk) 13:55, 24 August 2012 (UTC)

Actually, while we currently don't fully understand consciousness and free will, the answer will not at all depend on whether you believe in a soul or not. Goodbye Galaxy (talk) 14:39, 24 August 2012 (UTC)

Not in the sense as being directly relevant to autonomous machines, but it is when comparing a human being to a machine. The concept of a soul (or mind) is linked to having a true 'will', in contrast to a purely materialistic/mechanical understanding of agency. So in determining whether a machine can have a 'free will' in the same sense as we have, this is a valid question. I like a quote by Blaise Pascal on this topic :"Man is to himself the most wonderful object in nature; for he cannot conceive what the body is, still less what the mind is, and least of all how a body should be united to a mind. This is the consummation of his difficulties, and yet it is his very being.". - Lindert (talk) 14:49, 24 August 2012 (UTC)

The Nico robot from Yale has been making news lately because it can reportedly self-identify in a mirror test. Nico's creators have been doing this work for a long time: here's a 2004 press story about "ending artificial intelligence" and to test cognitive theories on the robot. More information is available at Yale Professor Scassellati's robot research web page: " Human behavior has been studied from many perspectives and at many scales. Psychology, sociology, anthropology, and neuroscience each use different methodologies, scope, and evaluation criteria to understand aspects of human behavior. Computer science, and in particular robotics, offers a complementary perspective on the study of human behavior." Nimur (talk) 15:00, 24 August 2012 (UTC)

Quite a lot of people seem impressed by the robot, as they were by the chimps, elephants, magpies, owl, and pigeons (with training, like the robot) that also passed the test. I would like to see some news articles that reach for the opposite conclusion, namely that the mirror test means nothing and all those animals are probably just the same as robots built from protein.  Card Zero  (talk) 16:00, 25 August 2012 (UTC)

Are you thinking of the recent Futurama episode, Free Will Hunting? The answer is trivially yes, if you consider humans devices. Volition is the faculty of humans and other higher animals that lets them choose a course of action when none is forced upon them. Plants and simple animals react automatically to various stimuli, protozoa swim towards or away from various chemicals, plants grow toward the sun. It is automatic and without deliberation. There is no such automatic stimulus that forces you to choose to watch a comedy or a thriller, or decide to go for a walk, rather than watch a movie. If we did not have volition we would likely never get out of bed. Buridan's ass doesn't starve because it does have a primitive form of volition.

A sufficiently complex machine that could learn and which had basic drives could be designed to have, that is, to develop, volition. Not programmed. Designed. We are nowhere near being able to do that, but we know it is possible in principle because we are examples. The freedom of an individual's will is not freedom from the laws of physics, but freedom for external control. Free will is not lack of control, but autonomy--self control. There is no reason to believe a "robot" could not in principle be created which developed volition and possessed autonomy. μηδείς (talk) 17:33, 24 August 2012 (UTC)

To be fair, it's a tautological arguement. We could also have the illusion of volition: that is, we could all be preprogrammed for every single choice we make, down to the smalled minutia, and merely have the illusion that we had had the ability to chose. The key question is how to distinguish between having a genuine choice, and having the illusion of a genuine choice. If you can explain how to tell which state we exist in, it's an interesting answer. Asserting we have volution is one thing, establishing that we do (as opposed to just the illusion that we do) is a different thing. --Jayron32 18:03, 24 August 2012 (UTC)

To have self control, you have to have a self. I agree with Lindert — you can't have a self if you don't have a soul. However this does seem to be getting beyond the scope of the science desk. --Trovatore (talk) 17:51, 24 August 2012 (UTC)

You are begging the question. First, we could arbitrarily assert that maybe we don't "really" exist just as easily as we can assert that maybe we don't "really" have free will--whatever "real" existence and "real" free will are. But the words choice and volition obviously do apply to real world situations. The fact that in reality we only ever follow one course of action at a time doesn't mean that we didn't choose that course of action. And we simply are our bodies. There is no "we" apart from our bodies that would have free will if our bodies didn't "force" the "real" us to do things. We, as the type of bodies we are, have the ability to initiate action among an infinite number of possible paths even if external stimuli are insufficient to force us to act. The fact that our bodies do this according to some biochemical mechanism doesn't mean that it isn't "we" who are choosing, because "we" are those bodies. To focus on the question asked, there is no reason to believe it would be impossible to create a machine that would develop the ability to make choices between various possible courses of action open to it autonomously. The freedom in free will is ethical, not metaphysical. Free will is a moral and legal term describing choices we make deliberately and without coercion by another person. It has nothing to do with the mystical and incoherent notion that we are ghosts trapped in bodies that act against us. μηδείς (talk) 18:38, 24 August 2012 (UTC)

See, I simply disagree with you that we are simply our bodes. If we were, there would be no qualia at all. Physical considerations about our bodies might well explain all externally observable behaviors, but they cannot explain why there is anyone there to notice them. If we were simply our bodies, we would be p-zombies. --Trovatore (talk) 19:10, 24 August 2012 (UTC)

I never said we are "simply our bodies" in the sense of being mere matter. Bodies have substance and form, the have qualities, and stand in relationships. There are all sorts of things, like Beethoven's 9th Symphony, which exists, but are in no way bodies. You seem to be taking a rather naive form of atomistic materialism as your foil. I believe that shadows exist. I do not believe that they are bodies, or have mass. μηδείς (talk) 22:30, 24 August 2012 (UTC)

I've not said one way or the other whether I agree with you or not about whether or not we have volition or free will or choice or whatever series of close synonyms you wish to use. The issue I have raised is whether or not you have logically established that we have such ability. That is, if you are going to make an argument in favor of the existance of volition, you need to use the basic rules of logic to establish that having volition is an unavoidable conclusion to reach, in opposition to the counterproposal, that we merely have the illusion of volution. That is, I'm not arguing whether or not we have volition with you, I'm arguing that you haven't actually established that we do. You've asserted, a priori and without logical connection to established facts, that we do have volition, and have hand-waved away any counterargument that any evidence of volution could be reinterpreted as something else entirely. Calling something "mythical and incoherant" or mischaractizing the opposing proposition in unflattering and belittling terms is not a refutation. It is avoiding the question. The question has been put before you: based on the evidence of what we experience, how does one distinguish between volition (the ability to make choices) and the illusion of volition. --Jayron32 18:59, 24 August 2012 (UTC)

One does not need to "logically establish" (derive from arbitrary axioms?) that which is self-evident. I take it as given that you have the choice whetehr or not to respond to this post. I refuse to attempt to prove that you have that choice, it would be to attempt to prove what is prior by what is subsequent. See Aristotle's Metaphysics: "That nature exists, it would be absurd to try to prove; for it is obvious that there are many things of this kind, and to prove what is obvious by what is not is the mark of a man who is unable to distinguish what is self-evident from what is not." μηδείς (talk) 22:30, 24 August 2012 (UTC)

What makes it self-evident? That you find it inconvenient to need to prove it so? --Jayron32 05:13, 25 August 2012 (UTC)

The concept of logical proof rests on the notion of premises which are assumed to be true, either self-evident or already demonstrated to be based on something prior which is ultimately self evident. You cannot demand proof of everything--that's not a matter of convenience--it's a matter of non-contradiction and infinite regress. That is Aristotle's point. I am quite sure that you know certain things that are self evident. For example, if someone were to punch you in the face, would you want to prove it based on various axioms before you reacted?

It is self-evident that we face all sorts of options among which we can chose and that we do select among those options even when nothing external to us forces one on us. The fact that we do make such choices is what the name volition is applied to. The self-evident facts lead to the naming of the concept. We don't start with some concept volition out of no where and then seek to find facts in reality to prove the concept is valid. Likewise, we all know of cases where we have done things because we were happy to do them of our own accord, or cases where we did things we would not otherwise have done were we not threatened by others. This is self evident. We name acting of our own accord free will and acting under threat as coercion, because it is useful to name these things, not because we started with a concept free will from out of the blue and then sought to find things in the real world that prove its existence. The facts are prior, and do not require proof.

If a determinist wants to argue that we don't "really" have free will, he is not actually denying that there is no difference between an individual doing what he wants gladly and being coerced by some other individual to do something he would not otherwise have chosen. He is not using the term free will in the original sense. It is up to him to come up with a coherent explanation of what it is he is denying. Ultimately what the determinist is saying, although he will rarely admit it, is that he is not free because his body forces him to do things he would otherwise not have chosen to do. To him, his body is essentially another person from his "true self". The ironic thing is that the determinist poses as paragon of science, yet treats himself as a ghost imprisoned in a zombie. μηδείς (talk) 18:12, 25 August 2012 (UTC)

The key distinction in your punching example is the difference between an observable action, and the explanation for that action. We wouldn't have to debate that the punch occured. What would need explanation is why the punch occurred. I'm not asking that you prove that humans (or any living thing) performs certain behaviors, what I am asking is for a simple proof of the explanation that they perform those behaviors because they had the option to do something else. If I push a ball down a hill, it rolls to the bottom. If the ball is self aware, and believes itself to have had the option, and believes that it chose to do so, or more to the point, that it was programmed to believe that it chose to do so, how does the ball distinguish between that state and a state where the ball went down the hill because of it's own choice? The axiom is that the events happen. The two opposing propositions are the reasons why the event happen. What is the reason to pick one proposition over the other, besides "because I say so" or "because it is obvious". What makes it obvious? --Jayron32 20:48, 25 August 2012 (UTC)

"If the ball is self aware"? You are happy to entertain such nonsense as balls being self-aware, but hold that it is controversial whether people make choices between options? That is precisely the sort of thing I am not willing to take seriously. I already told you that whatever the mechanism by which your body makes decisions, you are your body, and if nothing outside your body coerces it, your body's decision is free. If you disagree with that, it is up to you to coherently explain why you are not your body, or why the uncoerced actions of your body are unfree. μηδείς (talk) 02:25, 26 August 2012 (UTC)

I've never said that I was anything more than my body. You just invented that objection to my request as an attempt to deflect from the actual question. Let me simplify the question before you, because you have either redirected it or patently refused to answer it every time it was posed. What is the evidence that volition is a phenomenon, and why does that evidence point unambiguously towards volition existing? As an aside, I am finding fault with your arguments, not your conclusions. I have never once said, or implied, or made any statement which could reasonably interpreted to mean that we don't have volition. What I have said was that you have provided no argument or evidence to that effect. I have no problem with your conclusions. It's your methods that you use to get there that are faulty. --Jayron32 02:31, 26 August 2012 (UTC)

You are faced with an infinite number of options at any point, and yet you act. You can have Chinese, Italian, pancakes, dogshit, or an infinite number of combinations, or nothing, for dinner. Yet you act. That is what is called volition, that you act, although no force like sunshine on a plant makes you grow automatically, without you making or refusing to make a choice. That is what is called volition. The fact of your acting even though nothing external to you forces you to do so exists (whatever you call it) and we give it a name, in this case, volition. Asking that it be proved to be volition means you know what volition is ahead of the facts of reality that prompt you to name a real phenomenon. That is the essence of foolishness. I apply names to real phenomena that already exist in reality; I don't start with a bunch of meaningless concepts, then look for things in reality to fill them. Do you? Unless you radically change your line of questioning I doubt I will answer you further on this topic. I now what I know. If you don't find what I have to say helpful, then far be it from me to waste your time in debate. μηδείς (talk) 04:03, 26 August 2012 (UTC)

The model of free will which I personally prefer is that free will is neither random nor determined - not the result either of quantum noise or of the orderly operation of physical law - but rather reflects a causality violation induced by the localized and highly regulated use of precognition, otherwise a dangerous and pathological condition. If you have a machine that spits out a number a second before you enter it, and you feed it the number it itself spit out, then it has free will. Nothing in this universe determines what that number will be, nor is it random. Some authors such as Roger Penrose have speculated on weird quantum phenomena in the nervous system, though I don't think this is what he had in mind. In any case, some unusual phenomenon would be required. I am suspicious that mental states as we experience them do not correspond one-to-one with physical states of the underlying "machinery", and thus the subjective appearance of reversal of entropy or other causality violations may be possible even though physical laws are not broken in terms of the technologically observable qualities of the system in which they are encoded. The machine would need to duplicate this alleged mode of functioning, which even I postulating it have only the haziest notion about. Wnt (talk) 22:12, 24 August 2012 (UTC)

My pet goldfish has more "free will" than any machine anyone has ever invented. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:13, 24 August 2012 (UTC)

Correct. Your pet goldfish has a rudimentary faculty of volition, it is self-determined, rather than externally constrained, and it surpasses the nature of any so-far artificially designed agent. μηδείς (talk) 22:33, 24 August 2012 (UTC)

A machine with free will (arbitrary break 1)

We are all mathematical algorithms, there is no such thing as a physical universe, all that exists is math. Qualia are computational states of algorithms. Count Iblis (talk) 22:38, 24 August 2012 (UTC)

We are not mathematical algorithms at all, there is no such thing as math: all that exists is the physical universe.... AndyTheGrump (talk) 22:44, 24 August 2012 (UTC)

The truth, as usual, lies somewhere between those 2 extreme positions. -- ♬ Jack of Oz ♬ ^{[your turn]} 22:49, 24 August 2012 (UTC)

No. The truth is that all that exists is the physical universe by definition. To say otherwise is farcical. 203.27.72.5 (talk) 23:21, 24 August 2012 (UTC)

Not to spoil the fun by throwing in a reference (which suggests this should really be running on the humanities desk, or maybe misc, since we're well into philosophy and logic), but try some Wittgenstein:

1 The world is all that is the case.

1.1 The world is the totality of facts, not of things.

1.11 The world is determined by the facts, and by their being all the facts.

1.12 For the totality of facts determines what is the case, and also whatever is not the case.

1.13 The facts in logical space are the world.

1.2 The world divides into facts.

1.21 Each item can be the case or not the case while everything else remains the same.

Tractatus Logico-Philosophicus. 86.169.212.200 (talk) 21:05, 25 August 2012 (UTC)

Correct me if I'm wrong, but haven't later philosophers rejected this position - including Wittgenstein himself? AndyTheGrump (talk) 04:15, 26 August 2012 (UTC)

It is still true that math exists. To say otherwise would cause great distress to the workers at the Mathematics Reference Desk. And it is still true that not everything is math. And it is true that not everything is encapsulated in "the physical universe". For example: ideas, thoughts, feelings, mathematical concepts ... -- ♬ Jack of Oz ♬ ^{[your turn]} 05:09, 25 August 2012 (UTC)

What is an thought besides a collection of electrical signals firing along synapses in your brain? Is that not physical? --Jayron32 05:15, 25 August 2012 (UTC)

Let me just point out that 203.27's supposed "definition" of the universe pre-supposes that everything in the universe is physical. That is just about the most unscientific and prejudiced and close-minded position one could possibly take. It's also not a universe that I have any knowledge or experience or understanding of. -- ♬ Jack of Oz ♬ ^{[your turn]} 10:11, 25 August 2012 (UTC)

I'll note by my personal crazy model above, everything actually isn't math - math is deterministic, and the point of the causality violation is to create an opening for something outside the known universe, beyond our ability to examine and perhaps to comprehend, to potentially affect it. The free-willed decisions actually all become boundary conditions of the universe. Wnt (talk) 12:50, 25 August 2012 (UTC)

It is a World 2 object in Popper's three worlds ... besides being a collection of electrical signals firing along synapses in your brain. To put it that way is true, but reductionist - other collections of electrical signals firing in your brain might not be thoughts, but smells, or migraines, or fits, so a higher-level description is commonly more meaningful. (Wait, all those things are probably world 2 objects as well. Damn. Still, a thought is a thing in its own right, an emergent thing.)  Card Zero  (talk) 15:40, 25 August 2012 (UTC)

You are correct- things like mathematical and sciontific concepts are not part of the physical universe by any menes.Aliafroz1901 (talk) 10:45, 25 August 2012 (UTC)

Or maybe they are, the jury is still out, but the effort put into discussions like this are probably better put into articles like physicalism. Sean.hoyland - talk 11:20, 25 August 2012 (UTC)

Yeah, but then we'd need sources. Philosophy is like feces or potential employees - everyone has excess to give away, but who wants to consume it? Wnt (talk) 12:46, 25 August 2012 (UTC)

Like I said above, everything is math. When we assume that what we experience is a physical world that is somehow more than a purely mathematical entity, we actually don't know what that fundamentally is. So, assuming that a physical world that is different from pure math exists is religion, it isn't science. Most scientist do believe in a physical world, but then more than a century ago, most scientists were deeply religious people.

If you feel pain, then this is not fundamentally caused by electrical signals, it is caused by the computation your brain performs. A huge analogue computer that would run the same algorithm as your brain is running and processing the same data would experience the same pain, even though it consists of gears. Count Iblis (talk) 19:10, 25 August 2012 (UTC)

So, if nothing physical exists then what's running the algorithms? 203.27.72.5 (talk) 20:20, 25 August 2012 (UTC)

The algorithms are not really run, they only exist in a mathematical sense. All possible algorithms thus exist. One of these algorithms is the formal description of your brain at this moment when you read this part of the sentence, one slightly different algorithm is the formal description of your brain at this slightly later moment when you read this. Count Iblis (talk) 04:07, 26 August 2012 (UTC)

To answer the original question, it is easy to create a machine with free will as it is conventionally defined. The creation process is called Procreation. --BozMo talk 21:34, 25 August 2012 (UTC)

Our brains can take in information and we can use that information — plus our existing world views, emotional states, and what have you — to make deliberative decisions about our actions. We can weigh possible outcomes, things we desire or desire to avoid, and come to conclusions. We can even come to very unintuitive or unexpected conclusions. We can use information, values, and empathy to decide what sorts of activities we agree we feel comfortable undertaking, and those which we would desire to never undertake. To me, this is as much as anyone seems to ever really mean by "free will" — I don't actually see debates about causality and materialism to be germane to the topic. Even setting aside the question of what consciousness really is — we have no clue, and it is a mighty significant thing to know nothing about when talking about such things — to me all anyone really wants to know is, "Are we responsible for our actions? Do we actually make decisions?" We feel that we are. We act like we are. Very few people who are not looking to excuse their prior actions ever seem to really ascribe to the philosophy that they are completely out of control of their own actions. That strikes me as pretty "good enough." I am not quite willing to say that my consciousness is totally illusory — it feels pretty "real" to me, and though that is just one datapoint, over time I've come to believe (when I ignore all of the postmodernism and language-games talk that was drilled into me by professors and try to evaluate it in a completely honest, personal way) that it's actually a pretty significant datapoint.

But moving to the meat of the original question: I see no a priori reason to think that we could not imbue a machine with the same faculties as a human brain. This would include whatever appears to be a component of "free will", as defined above. How to do this, I have no idea, and I doubt anyone else alive does either. The human brain is still virtually terra incognita when it comes to understanding the physical basis of consciousness. I suspect we're still a long way off from making sense of it. We probably need to make sense of what makes us us before we can make other things us. --Mr.98 (talk) 01:54, 26 August 2012 (UTC)

Bodies (hylomorphic substances) and those things that exist in relation to bodies (aristotelian categories) exist. Mathematics doesn't exist by itself. If it did, would it be in base two? Or base ten? Or base e? The assertion is absurd. Mathematics is a perspective on reality that observes quantity but ignores quality. Consciousness is not a thing, or a body. Consciousness is a relationship, a sort of harmony that exists between certain types of bodies, in respect to their forms, and mathematics is a complex sort of such relationship. To insist that mathematics as such existed back when there were only fish or only molten planetoids or dense clouds of plasma makes as much sense as insisting that documentary films did. μηδείς (talk) 02:18, 26 August 2012 (UTC)

Low signal to noise ratio

I'm looking for a word to describe the problem caused by a low signal-to-noise ratio. I'm thinking of a word like distortion but I can't figure out what the correct word is. ike9898 (talk) 18:12, 24 August 2012 (UTC)

I've always heard it called "noise". If there is a low signal-to-noise ratio then, by definition, what you have is too much noise. --Jayron32 18:23, 24 August 2012 (UTC)

...or too little signal. StuRat (talk) 19:36, 24 August 2012 (UTC)

If you're talking about the response of an analytical instrument, you may be approaching the detection limit. 203.27.72.5 (talk) 20:01, 24 August 2012 (UTC)

"noise" is the word I would pick too. Sean.hoyland - talk 06:10, 25 August 2012 (UTC)

How about "static" or "radio interference". ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:55, 24 August 2012 (UTC)

The problem? There are many different problems associated with poor signal-to-noise ratio! There is bit error in digital communications; there are false detections; missed detections; in the analog domain, there is poor signal intelligibility; frequency discrimination error; in control systems, there are invalid or uncommanded actuations; ... outside of communications, there are other fields with signal-to-noise problems: in music, there are aesthetic considerations to poor signal integrity; ... Without a little context to define the problem, we can't really ascertain the correct word to describe it. Nimur (talk) 00:30, 25 August 2012 (UTC)

I see. The context has to do with a laboratory method for measuring a physical property.

August 25

What if Earth stopped rotating?

Assume that its rotation is slowed gradually enough that the deceleration doesn't cause any major effects. --168.7.232.12 (talk) 00:35, 25 August 2012 (UTC)

We get this question a lot. If I may quote myself, from March of this year, when I quoted myself from a similar question in September of last year: (I have taken some liberties to modify the quote to increase relevance to the current question)

“ The answer to this type of physics question always depends: how would [the earth stop spinning]? If you can specify that, we can follow through with the consequences by solving the equations of motion for the Earth-Moon[-Sun] system.

For example, if you hypothesize that a giant comet large and fast enough to change the [Earth's rotation] impacted our planet, .... well, we would need to calculate the effect that such a large comet has on the orbits of Earth and everything else in the solar system, too. We could solve that problem by setting up an n-body problem to model the solar system, including Earth, Moon, Sun, and other planets; and we would use perturbation theory to study how sensitively the system reacts when we add in a new comet on a course to impact the moon. The results are difficult to compute, but this can be done in a reasonable amount of time with a reasonable amount of effort.

...

On the other hand, if you just want to make something up, "just imagine" that the [Earth] magically changes its [rotation], all bets are off. We can't meaningfully speculate what consequences follow when one law of physics breaks "because of magic." Anything could happen. Everything we know about the way the Moon's orbit couples into the Earth's rotation depends on the rules of physics as we currently understand them.

” — Nimur

So - does that answer your question? Anything. Anything could happen. Nimur (talk) 01:00, 25 August 2012 (UTC)

So, hold on, how does a comet on a course to impact the moon cause the Earth to stop rotating? 203.27.72.5 (talk) 01:14, 25 August 2012 (UTC)

In general, it does not. You could conceivably concoct some unusual special circumstance where the angular momentum of the comet and the Earth's rotation were perfectly matched up so that it would cancel to zero after a collision, and then solve for the necessary conditions that would make such an impact possible. Nimur (talk) 04:06, 25 August 2012 (UTC)

I still don't see why the moon is coming into this... 203.27.72.5 (talk) 04:09, 25 August 2012 (UTC)

Also, my original comment was addressed to a similar question, linked above, about the moon ceasing to revolve around Earth, ... so that might be the source of the confusion. Nimur (talk) 04:11, 25 August 2012 (UTC)

The OP specified a gradual slowdown. At the very least, doesn't the rotation help distribute the heat through the atmosphere? If so, wouldn't the same side facing the sun all the time cause big-time trouble? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:59, 25 August 2012 (UTC)

Well, that raises an interesting problem to figure out, and that is what does "stop rotating" mean. Stop rotating relative to the sun (i.e. the solar day) or stop rotating relative to the background stars (i.e. the sidereal day)? In the former case, the same side faces the sun all the time (this is roughly what Mercury does, IIRC), but from an observer hanging outside the solar system, the earth would turn very slowly in order to maintain that same side facing the sun. In the latter case, the sun will rise and set (from the earth's perspective) over the course of a year, but an outside observer would view the earth as not rotating at all. Yet another complication from the poorly thought out question... --Jayron32 05:10, 25 August 2012 (UTC)

Mercury rotates at a rate such that the sun (roughly) stops at perihelion when the tide is strongest. —Tamfang (talk) 00:39, 26 August 2012 (UTC)

Um, Bugs, if the Earth 'stopped rotating', the same side wouldn't face the sun all the time, given that the Earth goes round it once a year... AndyTheGrump (talk) 05:07, 25 August 2012 (UTC)

OK, "stopped rotating" in relation to what? The Andromeda galaxy, perhaps? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:09, 25 August 2012 (UTC)

Ooo, can somebody link to that thought-experiment about a bucket of water rotating, and what it is rotating relative to? I can't remember what it was called, but I seem to recall that serious scientists disagreed and it included Einstein's opinion somewhere. 86.169.212.200 (talk) 14:42, 25 August 2012 (UTC)

I don't know a good link (I read about it in a book) but it is a very interesting thought experiment. The idea is that you can tell if a bucket of water (or just two masses joined by a pieces of string) is rotating just by looking at the shape of the surface of the water (if it is rotating, the surface will be curved), without reference to anything external. The question is then what happens to a bucket in an otherwise empty universe. It is meaningless to ask whether it is rotating or not because there is nothing for it to rotate relative to, so is the surface of the water curved or flat? (Or, is the pieces of string taut or slack.) I'm not aware of there being a generally accepted answer. --Tango (talk) 19:49, 25 August 2012 (UTC)

Bucket argument is the article. See also Mach's principle. -- BenRG (talk) 22:09, 25 August 2012 (UTC)

• There was some National Geographic mockumentary about this idea, which I assume is where all the questions come from. I might offend the local copyright clergy if I post a link, but let's just say that "Aftermath: When the Earth Stops Spinning" is abundantly known to YouTube. See also [14] Wnt (talk) 12:43, 25 August 2012 (UTC)

However improbable stopping Earth's rotation is, we can still describe what conditions on Earth would be like. Assuming that the Earth becomes tidally-locked to the Sun, the Sun-facing side would be very hot, the far side very cold. This would induce powerful winds flowing along the surface from the dark side to the Sun-side, with high altitude winds in the opposite direction. It is likely that there will be a zone, with the Sun low on the horizon, where there would be begin conditions for human life. However, it is likely that most life would find it hard to adapt to 24hr sunlight, with no seasonal variation. CS Miller (talk) 14:04, 25 August 2012 (UTC)

If we're ignoring the physical effects of the transition, we can certainly ignore the biological effects. The idea of life living near the terminator on a tidally-locked planet has been explored in science fiction, but it would probably be difficult for complex life to thrive in such an environment. Simple life (bacteria, etc.) living underground where the extreme climate can't affect them should be fine, though. --Tango (talk) 15:11, 25 August 2012 (UTC)

I was going to say they would need to cancel As the World Turns, but they apparently already did so, preemptively. :-) StuRat (talk) 20:06, 25 August 2012 (UTC)

The Earth's rotation is already slowing due to tides and the expanding orbit of the moon. μηδείς (talk) 02:12, 26 August 2012 (UTC)

Take the OP's question as stated, without the carping about how it could be achieved. Assume that God, or Alien Overlords, either "Will" it, or apply "tractor beams" to slow the rotation over a reasonably long time, to avoid the H.G. Wells effect (from a story in which the Earth stopped abruptly, but people and things shot forward at their previous speed). Assume that "stoppage of rotation" means that one meridian has High Noon without change, and another 180 degree opposite meridian has perpetual Midnight. The Earth makes one rotation per year. Assume the Sun always shines over the Prime Meridian in Greenwich, (so the Sun "never sets on the British Empire.") London would get very, very hot, and likely become uninhabitable, as would much of Europe.Places along the International Dateline at the Antimeridian would get very, very cold, likely become uninhabitable, and agriculture there would become very difficult. Lots of ocean creatures would die from it being too hot or cold. The ocean near antimeridian might become permanently frozen. There would be a "Happy Medium," or "Goldilocks Zone," perhaps a bit Sunward from the 90th meridians east and west, only a small fraction of the present zone where people flourish, where the temperature and insolation would be most advantageous. A large portion of the population would likely starve, burn, freeze, or die in conflict as people sought to migrate to the place where it was not too hot and where crops could be grown. Some extreme weather might occur, with massive storms due to the vast temperature differential. Edison (talk) 04:10, 26 August 2012 (UTC)

Why didn't the world enter a nuclear winter in the mid-20th Cent.?

Yes, this is two nuke-related questions in less than a week for me. I'm weird like that. Anyway...

These guys estimate that a "nuclear conflict ... with 100 Hiroshima-size weapons ... would significantly disrupt the global climate for at least a decade." By this chart's reckoning, 116 atomic bombs were detonated worldwide in 1958; 71 in 1961; 178 in 1962; and no less than fifty on a yearly basis from '63 through '80. However, according to this, there has been absolutely no measurable decrease in the amount of sunlight that reaches the earth's surface because of any nuclear detonation or series of detonations ever.

Is it just me or does all of this seem somewhat contradictory? Since most nuclear weapons are at least in the Hiroshima range (many of them larger by several orders of magnitude), and since we clearly had periods in the 20th century where well in excess of one hundred nuclear weapons were detonated within several months of each other, shouldn't we have seen some sort of effect on the weather, even a minor one, at some point between 1958 and 1980, given the estimate I initially quoted? Evanh2008 ^{(talk|contribs)} 01:29, 25 August 2012 (UTC)

The climactic effects of nuclear weapons come from burning lots of stuff (cities, forests, what have you) — it's about releasing carbon dioxide into the atmosphere. Only two of the nuclear weapons in the 20th century were set off over areas with significant stuff to burn. The others were set off on remote atolls or islands, in deserts, in the very high atmosphere, or underground (the majority). A more interesting question to me would be whether there were any measurable effects from the amount of carbon put into the atmosphere during World War II, when there were systematic programs of city burning perpetuated by many of the participants. As for mass burning affecting climate change in general, one of the theorized explanations for the Little Ice Age is a decrease (because of rapid depopulation) of planned burns that had gone on for centuries in the New World. Just an interesting idea. --Mr.98 (talk) 01:37, 25 August 2012 (UTC)

It's not about carbon dioxide. See Nuclear winter. It's about soot and other particulates that get kicked up into the atmosphere. 203.27.72.5 (talk) 01:51, 25 August 2012 (UTC)

Well, right, other stuff as well. My point still stands... --Mr.98 (talk) 23:25, 25 August 2012 (UTC)

Some researchers have speculated that we may have had a "petit nuclear winter" in the second half of last century [15]. 203.27.72.5 (talk) 02:17, 25 August 2012 (UTC)

Seems unlikely to have anything to do with testing, though. The amount of particulate matter added to the atmosphere by nuclear testing is but a drop in the ocean of human-added effluents in the late 20th century. The logic of that particular paper doesn't strike me as terribly compelling. --Mr.98 (talk) 23:25, 25 August 2012 (UTC)

I'm inclined to take that first source (claiming no effect) with something of a grain of salt; it was published in June 1957, prior to really large-scale atmospheric testing. (1956 had only 33 atmospheric tests, 1955 just 23; there were fewer than 20 per year between 1951 and 1955, and just 6 in total between the end of World War 2 and 1950.) Further, the publication was prepared by the Armed Forces Special Weapons Project of the Department of Defense—an agency that might have a certain interest in concluding that nuclear weapons use had fewer long-term hazardous effects. Even then, they acknowledge in the fine print that firestorms caused by large-scale conventional bombing had been known to affect weather; it seems to be splitting hairs to absolve the bomb for responsibility for the fires it starts.

When you look at the number of nuclear tests each year, you also need to consider where those tests occurred. (Take note of the terms of the various treaties described under Comprehensive Nuclear-Test-Ban Treaty.) While there were more than fifty tests per year from 1963 through 1980, there were fifty or more aboveground (atmospheric) tests in just '57, '58, '61, and '62. After 1963, there were never more than ten aboveground tests in any one year, and no such tests in most years. Underground tests – while certainly problematic for an assortment of reasons – would not be expected to have any major effect on climate. Tests that were conducted aboveground always took place in remote areas (deserts, oceans) where substantial fires would not be sustained by forests or buildings.

Finally, even if 1950s climate sensing and modelling technology failed to detect the effect of a few dozen explosions, one should not be sanguine about the effect of thousands of warheads (including large numbers of high-yield bombs) that could potentially be fired in a major nuclear exchange. TenOfAllTrades(talk) 04:40, 25 August 2012 (UTC)

Interestingly, there is a connection between climate change and nuclear weapons — but it's because many of the methods for making sense of climate change today originated in studying the dispersal of nuclear fallout. There was a good article on this recently in the Bulletin of the Atomic Scientists. (Incidentally, Samuel Glasstone was a very well-respected writer on the topic of nuclear weapons effects. Whatever he wrote then would have been accurate knowledge for its time. His Effects books — there are multiple editions — were government-produced works but they pulled no punches.) --Mr.98 (talk) 23:30, 25 August 2012 (UTC)

For real, measurable, global effects of nuclear testing, you may be interested in how bomb carbon factors in to carbon dating, as well as many other areas of Biogeochemistry. See e.g. [16] SemanticMantis (talk) 06:25, 25 August 2012 (UTC)

How many calories in a shot of vodka?

How many calories are in one shot (1.5 fl oz) of 80 proof vodka? Googling seems to give a variety of answers, but does about 100 calories per shot seem reasonable? Thank you, 99.92.102.199 (talk) 04:22, 25 August 2012 (UTC)

This site says there are 97 calories in a shot of Smirnoff 80 proof. Evanh2008 ^{(talk|contribs)} 04:27, 25 August 2012 (UTC)

This elegant website, http://nutritiondata.self.com gives excellent full nutritional data on all foods and beverages. It indicates 64 calories for one oz 80 proof. μηδείς (talk) 17:44, 25 August 2012 (UTC)

In Russia, vodka shoots you. Clarityfiend (talk) 21:36, 25 August 2012 (UTC)

Is that Yaakov Smirnov? μηδείς (talk) 02:10, 26 August 2012 (UTC)

Unless my subconscious is dredging up somebody's comedy routine, it's me. Or maybe it's the Smirnoff talking. Clarityfiend (talk) 04:48, 26 August 2012 (UTC)

Kuiper belt object

Are those objects orbit around the sun or are they just flying around randomly?184.97.233.160 (talk) 05:08, 25 August 2012 (UTC)

The article indicates they're in orbit, e.g. one of its members, Pluto, is in a significantly elliptical orbit. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:20, 25 August 2012 (UTC)

Also note that "flying around randomly" isn't possible. Since "an object in motion stays in motion (at the same speed and direction) unless a force acts upon it", they would soon leave the solar system. Therefore, they must be gravitationally bound to some object in the solar system, in this case, the Sun. StuRat (talk) 06:01, 25 August 2012 (UTC)

Good point. Tell me if I'm wrong about the following: My assumption about the Big Bang is that immediately afterward, things were pretty much "flying around randomly". Over time, they began to coalesce into various objects, like stars and planets and of course galaxies. Given the many billions of years since then, would it not be the case that there are far fewer objects "flying around randomly" than there might have been after the beginning? ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:07, 25 August 2012 (UTC)

Actually, the process is poorly understood, and we don't have a good answer for what happened. We know two things: from the Cosmic microwave background radiation we know that the very young universe was homogeneous: that is, it was evenly distributed and looked uniform in all directions and at all scales. The second thing we know is that it doesn't look like that today. What happened in between, that is what happened to cause the universe to go from a state of homogeneity to one of heterogeneity (from looking like milk to looking like cottage cheese) isn't well understood. This is explained at Structure formation. --Jayron32 06:15, 25 August 2012 (UTC)

"We know two things: from the Cosmic microwave background radiation we know that the very young universe was homogeneous: that is, it was evenly distributed and looked uniform in all directions and at all scales. The second thing we know is that it doesn't look like that today." actualy your post is partialy rong (at least if I have understood you correctly) because although the universe is not homogeneous at a small scale but it is homogenious at a large scale.

While it is tru that we do not know how the erly universe looked like the big bang article segests that there were far fewer objects "flying around randomly" just after the big bang than there are nau.Aliafroz1901 (talk) 10:32, 25 August 2012 (UTC)

What the universe looks like on a large scale is dependent on what the shape of the universe is, which is also something we don't know. If the universe is really infinite in extent, then yes, it is perfectly homogeneous on a large enough scale, because trivially any local unevenness "smooths out" when looked at from the perspective of infinity. The problem is a) this isn't exactly the same as what I said above, because in the early universe it was homogeneous at all scales, not just if you back out to (near) infinity. That is, under our current understanding of the early universe, it doesn't matter whether you look at it on the atomic scale, the human scale, the solar system scale, or the entire universe scale, it would all look homogeneous. Today, the only scale that may work on (and again, it depends on what the universe really looks like, which we don't have a firm grasp on at that scale) is the "entire universe scale". Today, the universe is decidedly heterogeneous on all other scales, rather self-evidently: I'm standing here, and I'm not standing over there. There's star material in some places, and not in others. There are atoms and molecules, and then there are places with empty space. In the early universe, this wasn't true. It was all a uniform matter/energy soup. The mystery is how it got from that state to what we have now. --Jayron32 14:20, 25 August 2012 (UTC)

That's not a mystery. Things gravitated together. The details may be complicated but we do basically know what happened. Biological evolution is very complicated but it would be misleading to say that there were only prokaryotes a few billion years ago and there are humans now and it's a mystery how that change happened. -- BenRG (talk) 21:52, 25 August 2012 (UTC)

Correct, and I never said you were fully rong-what I said was that you were partialy rong (which you mite not be of course).Aliafroz1901 (talk) 14:46, 25 August 2012 (UTC)

What I mean is are "ALL" the Kuiper belt objects are orbiting around the sun? What if some of them are too far away for the sun gravity or anything gravity to act upon them so aren't they just flying around randomly or just stand still? (I know they are, including the Solar system, also spinning around the galaxy too, in the big picture) Anyway they could flying around randomly in a smaller scale compare to galaxy scale. Just like Earth is orbiting the Sun but bigger scale, the Earth is also spinning around the Milky way galaxy.184.97.233.160 (talk) 08:03, 25 August 2012 (UTC)

Gravitation has an infinite range. Everything in the belt is under the influence of the sun's gravity. If they were standing still relative to the sun for an instant, they would still accelerate towards it and begin to move in it's direction. 203.27.72.5 (talk) 08:20, 25 August 2012 (UTC)

True, but at some distance objects will never complete an orbit during the life of the universe, so saying it is "in orbit" seems iffy. StuRat (talk) 08:32, 25 August 2012 (UTC)

The Kuiper Belt, and the Solar System itself, are defined as objects which are gravitational bound to the Sun. So, if some object is just "passing through" the Kuiper belt, fast enough to not fall into orbit, it isn't really a Kuiper Belt object (although it might be mistaken for one until it's motion is charted). StuRat (talk) 08:30, 25 August 2012 (UTC)

It is certainly possible to have objects passing through the solar system without being gravitationally bound to the sun (that is, without being in a closed orbit). They need to be moving quite fast, though. In fact, we can quite easily work out how fast. I will ignore any complications from interactions with planets or light pressure or any of that stuff, and just treat the situation as a simple 2-body problem. The thing that determines whether an object is in an open or closed orbit (ie. whether it can reach infinite distance or not) is its total energy, it's gravitational potential energy plus its kinetic energy. Note, gravitational potential energy is defined, for convenience, to be zero at infinity and to get more and more negative as you get closer to an object (this seems really weird, but you'll see why it is useful in a second). The total energy of an object will be the same at all points in its orbit (conversation of energy). If that total is positive, then that means the object will still have positive speed at infinite distance, so it is an open orbit. If the total is zero, then it will "come to rest at infinity", so it can reach infinity but only just. If the total is negative, then it would need to have negative kinetic energy at infinity, which can't happen, so the object can't reach infinity - this means it is a closed orbit.

So, to figure out how fast an object needs to be going to avoid being captured by the sun, we just need to calculate the (negative) potential energy at a particular distance and work out what velocity gives an equal (but positive) kinetic energy. Pluto is, on average, about 6 billion km from the sun, so let's use that as our example distance. Using the formula at gravitational potential energy, we get the potential energy (of a 1kg object - mass will cancel out when we calculate the speed, so it doesn't matter) to be 22 megajoules. If we convert that into a speed (using E=1/2 mv²) , we get about 6.6 km/s. Pluto's average orbit speed is 4.7 km/s (average speed isn't quite the same as speed at average distance, but it is close enough) so we can see that it is easily in orbit around the Sun. An object at the same distance travelling about 40% faster would not be in orbit and would eventually escape. --Tango (talk) 13:20, 25 August 2012 (UTC)

So what happen for the objects that outside the belt or outside of the Solar system? Are they going to fly around randomly?184.97.225.6 (talk) 21:30, 25 August 2012 (UTC)

Hopefully you'll find the Hill sphere article informative. If a body's orbit falls entirely within the Sun's Hill sphere (take a note of the calculation in that article's talk page, and at Talk:Comet, for some estimates about the diameter of the Sun's Hill sphere; it's bigger than once thought - big enough to encompass the Oort cloud). For some body in the galaxy whose path doesn't fall entirely within the Sun's Hill sphere, you wouldn't say it orbited the Sun. It might be within the Hill sphere of another star (or star group, like Alpha Centauri), so you'd say it orbited that, and its path would follow an elliptical orbit around that system's barycentre. But it might not be, so it would orbit the galaxy's barycentre, as the Sun does. The galaxy is mostly empty, so such an object could go a billion years without its orbit happening to take it close enough to something else - when it did, that could bend that nice mathematical ellipse a bit (but mostly not close enough for it to be captured in that something else's system). Although all the stuff orbiting in the galaxy is chaotic (it's a colossal n-body problem) it's not random or arbitrary; for most such things orbiting the galaxy's barycentre, their orbits are of near-mathematical elliptical perfection, over very lengthy periods of time. -- Finlay McWalterჷTalk 23:43, 25 August 2012 (UTC)

Estuary

"pollutants including heavy metals, PCBs, radionuclides and hydrocarbons from sewage inputs". What is the PCBs in this context stands for?184.97.233.160 (talk) 08:04, 25 August 2012 (UTC)

Polychlorinated_biphenyl 109.144.167.204 (talk) 08:09, 25 August 2012 (UTC)

Vaporizer, cannibis

Is it true that a vaporizer will virtually eliminate any risk of lung cancer or other cancers related to smoking? And is it possible to use a vaporizer with tobacco? ScienceApe (talk) 15:48, 25 August 2012 (UTC)

Only if you don't inhale. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:04, 25 August 2012 (UTC)

Wikipedia has an article titled Vaporizer (cannabis) which has some information you may seek. I don't know of the use of tobacco in cannabis vaporizers, but the have recently hit the market Electronic cigarettes which may or may not be similar in construction and use. --Jayron32 16:38, 25 August 2012 (UTC)

Unlike nicotine, cannabinol is a rather heavy molecule and not water-soluble. Vaporizers won't work at all well. Cleaning marijuana of stems and seeds and steeping it in hot but not boiling melted butter before then cooking the mixture in brownies will totally avoid the lungs, but not fat or cholesterol. μηδείς (talk) 17:39, 25 August 2012 (UTC)

Assuming inhalers are possible for THC, it might reduce the risk, since presumably there would be less "tar", but inhaling any foreign substance into the lungs carries some risk. Also note that the THC itself may continue to cause other problems, such as memory loss. StuRat (talk) 18:54, 25 August 2012 (UTC)

Note that the safety of vaporizers is being presumed - given the legal obstacles and recent nature of the advance, I doubt there have been large, careful, long-term studies. Remember that it takes only a small amount of a carcinogen to cause harm, and any new process of heating and other processing potentially could create one. It seems like a good bet that it's a good idea, but in biology only the actual data can give an answer. Wnt (talk) 20:15, 25 August 2012 (UTC)

Why do different air masses equilibriate slowly ?

When I open my refrigerator door to the open air, or an oven door, the air masses inside them equilibriate very quickly, generally within 15-30 minutes. Why does this not scale for large air masses in the atmosphere? 128.143.1.192 (talk) 23:00, 25 August 2012 (UTC)

Are you sure it doesn't scale ? That is, does 1000 times the volume take 1000 times as long to reach equilibrium ?

That 15-30 minutes is probably only that long because the solid components or contents of the oven or fridge continue to give off or absorb heat over that period. Similarly, heat is being added to the atmosphere from the Sun and ground/water, and removed by radiation into space, at all times, so never really reaches an equilibrium.

There are also differences in scale regarding what type of heat transfer occurs the most (radiation, convection, etc.). StuRat (talk) 23:11, 25 August 2012 (UTC)

Yes, there's wind and convection and so forth and yet a stationary front can take several days to become a shear line (when the sharp contrast ceases to exist and becomes more of a diffuse gradient). Why is it so slow? 128.143.1.192 (talk) 00:16, 26 August 2012 (UTC)

I would be quite surprised if such transfers scaled linearly (1000 times the volume takes 1000 times as long) due to the square-cube law (specifically surface-area-to-volume ratio effects). The amount of heat energy an air mass has scales with it's volume. 1000 times the volume of air means 1000 times the amount of heat energy which needs to be transferred to equilibration. However, the transfer itself only occurs on the interface between the two air masses. The interface and interface-related effects don't typically scale as the volume, but as the surface area. An airmass of the same shape but with 1000 times the volume would not have 1000 times the surface area, but only 100 times the surface area. Thus naively you would expect the heat transfer (if it proceeds by exactly the same process in the two cases) to take 1000/100 = 10 times as long for the larger air mass. Of course, the relevant surface area and interface effects aren't going to scale *exactly* 100 fold, and with the larger air mass there may be different effects (wind generation and Coriolis effects may come into play, etc.), but the square-cube law gives a good first-order approximation as to why a small mass cools faster than a large mass. -- 205.175.124.30 (talk) 01:35, 26 August 2012 (UTC)

Also, how good is the adiabatic approximation in the weather modelling of air mass interactions? 128.143.1.192 (talk) 23:01, 25 August 2012 (UTC)

DNA

Whats the significance of knowing that DNA is double helix? 203.112.82.2 (talk) 23:25, 25 August 2012 (UTC)

1) It's rather critical to knowing how it replicates (it unzips and both halves then form a new complete strand).

2) It's also critical to knowing how the genes are stored. StuRat (talk) 23:32, 25 August 2012 (UTC)

Actrually, neither of those necessitates the "double helix". If it just looked like a long ladder, it would still need to unzip to decode, and it would still replicate the same way. The deal with the double helix is is that it is a very efficient means of storing the information. If you think about how a telephone cord used to look (back when people had corded phones in their house), it's coiled up. The fact that DNA is coiled (rather than straight) allows it to fit a longer chain into a tighter space, and that improves the amount of information you can fit onto it. There's limited space inside a nucleus of a cell, and the way that DNA is coiled greatly effects how much information you can cram into it. The tertiary structure of DNA (how the double helix itself is packed) is also very important in this regard. --Jayron32 00:50, 26 August 2012 (UTC)

There's a nice diagram of that here. Coils upon coils upon coils. --Mr.98 (talk) 01:29, 26 August 2012 (UTC)

(ec) There is a famous line at the end of the original Watson and Crick paper: "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.". That was all they said about it at the time, but it was enough. Looie496 (talk) 00:51, 26 August 2012 (UTC)

Yes, but the base-pair organization doesn't have much to do with the double-helix structure. RNA, for example, doesn't form double helixes. It forms Stem-loop structures. The base-pair organization explains how DNA codes for gentic information, the double helix helps explain how DNA codes for so much information because it allows the DNA to fit more information bits into a much tighter space than a straight chain would. --Jayron32 01:11, 26 August 2012 (UTC)

RNA doesn't form double helices? Hmm... that'll be a big disappointment to the double-stranded RNA viruses and other organisms and cellular functions that depend on dsRNA (which include stem-loop structures, which are - double helical!). dsRNA tends to take on A-form double helical conformation. -- Scray (talk) 02:30, 26 August 2012 (UTC)

Yeah, you're right. I'm an idiot. Carry on. --Jayron32 05:01, 26 August 2012 (UTC)

To be clear, every nucleic acid, DNA and RNA alike, replicates based on a double-helix structure. In the case of RNA transcription, the DNA strands are parted and one is replicated by forming a temporary DNA-RNA double helix structure. In a sense, even the translation of proteins from RNA is based on the double helix, in the sense that tRNA base-pairs with the RNA on the ribosome. The double helix is important for lining up the right nucleotides for replication, for checking for errors afterward, but also for maintaining relative inactivity of the sequence afterward - a simple double-stranded RNA won't act as a ribozyme because it's just a straight rod, at least at the small scale relevant to forming catalytic sites. There are, of course, a great many little oddities that you could mention in regard to it - artificial nanoscale engineering of complex structures, sequence-specific reception of radio-frequency or terahertz signals, the ability of supercoiling to convert overall torsion of the structure into a separation of strands, or vice versa, the ability to nick the structure so that topoisomerase I can release said supercoiling, under control, the ability of PCNA and other proteins to clamp onto the strand and run it like a more or less smooth "string" through holes in a protein complex ... there must be thousands of specific relevant significances. Wnt (talk) 03:40, 26 August 2012 (UTC)

Now, that is a great answer... Well explained, Wnt. --Jayron32 05:01, 26 August 2012 (UTC)

August 26

landers and boulders

Neil Armstrong steered the Eagle to avoid a boulder field at the last minute. What can unmanned landers do about boulders? In this movie of Curiosity's descent someone says "We've found a nice flat place"; does that mean the lander had a way to look for one, or merely that "we" got lucky? —Tamfang (talk) 00:47, 26 August 2012 (UTC)

Mars today is much better mapped than the moon was during the 1960s. I wouldn't doubt that we have high resolution maps of the surface of Mars to a similar level that we have on earth; that was part of the idea of previous Mars missions like the Mars Reconnaissance Orbiter, which among its multifaceted mission is to scout and plan for landing sites for landers. --Jayron32 00:53, 26 August 2012 (UTC)

(ec)Recent landers on Mars and the Moon have benefited from surveys from long-term orbiting spacecraft like Mars Global Surveyor. That gives the mission planners a map from which they can select especially boulder-free areas. They pick an area quite a bit bigger than the error-bars for their lander's anticipated landing. -- Finlay McWalterჷTalk 00:58, 26 August 2012 (UTC)

It's worth mentioning the Lunar Orbiter program, the satellites which scouted the moon for Apollo landing sites. These remarkable gadgets exposed film, developed it themselves when orbiting the moon, and then tv-scanned the results back to Earth. They got a 2m resolution of the selected sites. The current Lunar Reconnaissance Orbiter gets about 0.5m resolution (so 16 times more data). Because its digital cameras aren't going to run out of film it can re-survey the same location over and over, when the Sun is at a different angle: comparing the shadows on different pictures gives further clues as to the terrain. -- Finlay McWalterჷTalk 01:44, 26 August 2012 (UTC)

This NASA blog entry implies that mission planners relied on whatever surveys were available (for the Curiosity mission, those would be 0.3 meter resolution surveys from the Mars Reconnaissance Orbiter) to select a region that was as boulder-free as possible, and then prayed like crazy that they didn't make an unlucky landing. TenOfAllTrades(talk) 03:59, 26 August 2012 (UTC)