Wikipedia:Reference desk/Archives/Science/2015 March 9

= March 9 =

Does height matter when it comes to air pollution?
Does height matter when it comes to air pollution? I'm wondering whether living and/or working on the top floors of rise buildings would mitigate the effects of air pollution somewhat for polluted areas. If so, how high would it have to be to make a difference? WinterWall (talk) 03:40, 9 March 2015 (UTC)


 * Removal of pollutants by the building's HVAC system would be far more important. Short Brigade Harvester Boris (talk) 03:42, 9 March 2015 (UTC)


 * There's no central HVAC system at all, so there's no filtering at all. Just individual per-room AC units (that doesn't filter air at all, just re-circulates indoor air). WinterWall (talk) 05:47, 9 March 2015 (UTC)


 * It's hard to believe that a high rise would lack a ventilation system entirely. Without one, the air would soon become unbreathable. StuRat (talk) 05:54, 9 March 2015 (UTC)


 * As hard as it is to believe, central HVAC is an unaffordable luxury for much of the world, much like clean, breathable air. WinterWall (talk) 06:05, 9 March 2015 (UTC)


 * Yes, but that portion of the world lacks high rise buildings. I can't imagine a society that can afford to build them, but not to ventilate them.   BTW, note that I am only talking about the V in HVAC.  I can believe that it wouldn't be cost efficient to fully air condition a high rise at certain times of the day or year, when ambient temperatures are high and occupancy rates are low.  As for central heating, it may not be necessary in all places. StuRat (talk) 16:44, 9 March 2015 (UTC)


 * It depends on which pollutants you mean. Some are heavier than air, or are produced at the surface (like horse manure fumes in the olden days), while others are lighter than air (perhaps because they are hot) and/or vented in high smokestacks. StuRat (talk) 05:22, 9 March 2015 (UTC)


 * I'm concerned about PM2.5 particulates mostly, but PM10 as well. For my purposes, we can ignore the stuff like CO, NOx and greenhouse gases.WinterWall (talk) 05:46, 9 March 2015 (UTC)


 * Regional air pollution is generally assumed to be well-mixed through the planetary boundary layer, roughly the lowest 200 to 2000 meters of air depending on local conditions. So, in that case being in a high rise wouldn't matter much unless the building were exceptionally tall.  The exception would be if the local area around the building were a significant source of air pollution, e.g. heavy industry, freeways, etc.  In that case the local pollutants which haven't yet mixed through the air column might make the low levels worse, though in most areas this is not a large effect.  Dragons flight (talk) 18:01, 9 March 2015 (UTC)

How were comic books mass produced at the beginning of the 20th century?
I know with the printing press which of course long preceded the beginning of the 20th century, textual pages could be mass produced by setting metal type into a press, but panels of originally hand-drawn color artistry with hand-written dialogue in bubbles, when Jerry Siegel and Joe Schuster made one story, I'm sure they didn't redraw however many hundred or thousand (I don't know what scale "mass production" was at in their days, but I suppose it was more than a handful), how exactly was the load to be sold made? An army of lower-paid re-drawers? If technology, what were they using at that time? 75.75.42.89 (talk) 05:39, 9 March 2015 (UTC)


 * History of printing has a timeline which shows which printing methods were available in 1900. I'm not sure which were used for comics, though. StuRat (talk) 05:52, 9 March 2015 (UTC)
 * Easy. Four-color press. In 1896, the New York World was the first newspaper to use a four-color press, the result being the first color supplement and the first color comic, The Yellow Kid. --jpgordon:==( o ) 06:08, 9 March 2015 (UTC)
 * Mass produced comic books did not become popular until the 1930s, and by then, four color printing was 35 years old, and was sophisticated and highly automated. Cullen328  Let's discuss it  06:16, 9 March 2015 (UTC)

See our article Comics artist - there is generally a penciller, an inker, a colorist and a letterer. I suspect it was the same then, although some would probably have been done by less people. Richerman   (talk) 07:35, 9 March 2015 (UTC)


 * I'm not sure any of the above completely answers the question. As I understand is, the core of the question is how the printing plates, i.e. the negatives from which the actual paper copy is produced, were made. Offset printing is one answer, becoming available in the early 20th century. Before that, I suspect that artists had to manually prepare the printing plates, either via etching or engraving. --13:01, 9 March 2015 (UTC)


 * For information on the team of artists see Superman. For information on the process used see . Richerman    (talk) 17:07, 9 March 2015 (UTC)
 * None of which describes what process was used in the real early days, before the advent of offset printing (in 1904). Indeed, how were the color seps created in the 1890s? --jpgordon:==( o ) 18:16, 9 March 2015 (UTC)

Experimental report evaluations
Why do some experimental report writing guidelines advise against mentioning some types of human error such as reading off scales wrong or breaking fragile equipment or samples. Is this because it erodes the readers confidence in the results? 194.66.246.24 (talk) 10:59, 9 March 2015 (UTC)
 * If those sorts of errors were involved in the collection of that particular dataset, it should have been repeated from the start, not reported at all. 131.251.254.154 (talk) 13:16, 9 March 2015 (UTC)


 * Beginners often have a tendency to err on the side of giving too much information. Unless the specific nature of an error is necessary to allow a reader to evaluate the paper or to be able to repeat the study, is is often sufficient to say that an error occurred causing data to be lost.  Unnecessary detail makes a manuscript hard to read and understand: readers assume that if a piece of information is included, then it must be important, and they end up wasting time trying to figure out why it is important. Looie496 (talk) 16:11, 9 March 2015 (UTC)

Thrust Reversal - do the "thrust Reversal" doors take a force equal to the braking force on the aircraft?
On watching bucket-type Thrust reversal doors when in a plane during landing I noticed that the doors appear to be hinged on a quite small bolt. This made me wonder whether the doors, and hence the bolt, need to take a force equivalent to the braking force from the reverse thrust on the airoplane. My physics is probably at a bit more than high-school level, so fluid dynamics calculations are beyond me, so I was thinking in analogies with other mechanisms which reverse the direction of a force, such as levers and pulleys which obviously to lift a kilogram must support the weight of a kilogram.

Also - what would happen if a bolt did break and the doors flew off - would the plane come off the runway or is it something the pilot could correct for? -- Q Chris (talk) 11:16, 9 March 2015 (UTC)


 * The reverse thrust on each engine is applied to the buckets. However, there are two buckets on each engine so each bucket experiences only half the reverse thrust applied to its engine. The buckets are hinged about a pair of bolts, but there is also at least two other structural members that open and close each bucket, so the force on each bucket is divided between the bolts and the other two structural members. Finally, the reverse thrust developed by a jet engine is no more than about 60% of the forward thrust that can be developed by that engine.


 * When a pilot selects reverse thrust on all engines there is always the risk that it won't operate on one engine, leading to asymmetric reverse thrust. The authority of applying full rudder at touch-down speed must be sufficient that the pilot can manage this level of asymmetric thrust. Similarly, if reverse thrust operates normally after touch-down but later fails on one engine, the pilot must be able to manage the resulting asymmetric thrust using the rudder and asymmetric wheel braking. If the pilot feels the aircraft is at risk of drifting excessively off the runway center-line, for any reason, the pilot can cancel the reverse thrust at any time, as well as using asymmetric wheel braking. Dolphin  ( t ) 12:26, 9 March 2015 (UTC)


 * If the thrust reversal mechanism broke off, it would be a "flight control malfunction" per 49 C.F.R. §830.5(a)(1) (and probably several line-items in paragraph (a)(7) as well). What does this mean to mere mortals?  It means that for legal purposes, a thrust reversal failure as you described  is considered (by the NTSB) to be equal in magnitude to the wings falling off and the airplane exploding.  It doesn't get any worse, as far as the NTSB is concerned.  The operator must immediately notify the NTSB and a full Federal investigation will ensue.  The occurrence and its investigation report will enter the public record for all to see.
 * So, airline operators and aircraft designers work really hard to ensure that won't happen. The thrust reversal mechanism is designed to be sturdy enough to operate within the limitations of the aircraft.  Airline pilots who fly such aircraft know how to safely use the system without breaking it.  The very elaborate maintenance and accountability-chain works to prevent mechanical malfunction before it ever happens.
 * Even still, accidents happen; but you can bet that the aeronautical engineers who design these systems work hard to prevent it. Nimur (talk) 14:41, 9 March 2015 (UTC)


 * Also: The Airplane Flying Handbook has an overview chapter (15-14) on thrust reversers, giving a very high-level overview of the topic and the aerodynamic principles. The AFH directly refers you to the approved flight manual for each aircraft - all your safety and emergency/recovery procedures would be in the aircraft's manual.  You can buy manuals for small airplanes on the web or at your local airport - but be advised that air transport category aircraft (like jets that have thrust reversal) are very expensive.  If the jet costs a few thousand dollars per hour to operate, expect to pay a few hundred dollars for its operation manual.  You can find lots of PDFs of, say, the Boeing 737-200, on the web - but most of these are "flight sim" game manuals and don't accurately reflect real emergency procedures.  If you want the real deal, you need to get in touch with the manufacturer's sales representative.  Nimur (talk) 15:08, 9 March 2015 (UTC)

Thanks everyone - there was a lot of interesting information -- Q Chris (talk)

Naturally occurring cloud chambers?
Is it at least theoretically possible for certain meteorological conditions - saturated vapour in the air, warmer above, cooler below - to lead to a naturally occurring cloud chamber? - would be fun to see the ghost trails of muons flipping through the air as you walk through the countryside... My understanding is of the lay type, by the way - for a start, I don't understand why it has to be alcohol vapour and not water vapour in the chamber - is it just because it's more volatile?

Adambrowne666 (talk) 12:11, 9 March 2015 (UTC)


 * Yes, alcohol is typically used because it has a higher vapor pressure at moderate temperatures, and so it is easier to produce the (very) supersaturated vapor required for the cloud chamber effect.
 * While I haven't found any references to beautiful and striking condensation trails in the air - finding natural situations with appropriate ambient light, sufficiently-supersaturated water vapor, and sufficiently calm air seems difficult - I have found a couple of reports of ionization-induced cloud and droplet formation.
 * In 1962, Bernard Vonnegut reported on his visit to Yellowstone National Park, where he engaged in some experiments above and beyond those normally carried out by the typical tourist. In a letter to the Journal of Atmospheric Sciences, Vonnegut described how the necessary conditions for supersaturated water vapor formed above geothermally-heated springs and pools in the park, where near-boiling surface water sat just below sub-freezing winter air: .  (This is an inversion of the geometry of a typical manufactured cloud chamber, which places a cold surface below the vapor.)  He carefully extended a 500 microcurie polonium source(!) over the surface of the hot spring, and observed "...a small but distinct little cloud of fog could be seen beneath it, which indicated that condensation was probably occurring on the fast ions produced by this source."  (Go ahead, just try to get permission from the National Parks Service to try the experiment again today.)
 * Much more recently (2014), the Journal of Aerosol Science published a report from Jan Hovorka et al., describing the curious case of a cistern (a well for water) in an abbey in the Czech Republic: . Even on clear and sunny days when no rain falls from the sky, drops of water can be observed falling on the surface of the water deep in the well (about 19 m below ground level).  The paper's authors argue that the temperature gradient from ground level to the bottom of the well, combined with the humid conditions and various other factors, are sufficient to produce a layer of supersaturated water vapor in the well.  Ionization events occurring within this supersaturated layer are enough to trigger condensation and drop formation, leading to the sunny-day 'raindrops'.  TenOfAllTrades(talk) 12:59, 9 March 2015 (UTC)

02:35, 10 March 2015 (UTC)Lovely answer, thank you, Ten - all the better that it references Kurt V's meteorologist brother Adambrowne666 (talk) 02:35, 10 March 2015 (UTC)

Faecal transplants treatment but between species
Copied from WP:RDM. Nyttend (talk) 17:36, 8 March 2015 (UTC)

OK, I didn't know whether to ask this on the relevant wiki or here so forgive me if I'm barking up the wrong tree. Basically, I'm wondering what the consequences of a faecal transplant between two difference species would be, or any references towards this. Let's say, a human having a transplant with a dog. Or a horse. Or even a primate. What about the opposite? — Preceding unsigned comment added by 89.151.151.176 (talk) 10:10, 8 March 2015 (UTC)
 * Can we assume you mean facial transplant, not faecal?  Ghmyrtle (talk) 10:38, 8 March 2015 (UTC)

Nono, see http://en.wikipedia.org/wiki/Fecal_bacteriotherapy — Preceding unsigned comment added by 89.151.151.176 (talk) 10:42, 8 March 2015 (UTC)


 * No answer, but: There is some information in our article on gut flora on faecal / fecal transplants.  There is no specific reference to inter species transplants, though one of the references may have data.  --Cookatoo.ergo.ZooM (talk) 10:54, 8 March 2015 (UTC)


 * I doubt it is possible. Human to human transplantation is predictable, we know what infections to look for, and there is plenty of shit in the world. Why take the risk and perform an animal to human transplantation?--Llaanngg (talk) 20:23, 8 March 2015 (UTC)
 * Well it's almost certainly possible. But I agree with you that it probably isn't a good idea, or an effective therapy. OP can find more related info at our articles microbiome and human microbiome. SemanticMantis (talk) 16:10, 9 March 2015 (UTC)
 * "not possible" was probably the wrong word here. It's more like impractical, not feasible, or something in this direction. I also don't know whether some animal has the type of bacteria we want to transmit through this treatment.--Llaanngg (talk) 18:47, 9 March 2015 (UTC)
 * Yes, the whole point of fecal transplants is to help restore a human's gut flora to a state more normal for humans - and it is unlikely that inoculating a human with non-human feces would help accomplish that. SemanticMantis (talk) 20:41, 10 March 2015 (UTC)

Soul and neuron action potentials
Soul doesn't seem to give a conclusive answer, but still I wonder whether the origin of an action potential could be a valid inference for the existence of soul. Specifically, science explains the origin of an action potential in chemical terms, but doesn't seem to explain what ultimate cause triggers such a potential, and as such the origin of free will and thought. According to this, for instance, artificial cardiac pacemakers require a pulse generator typically powered by a lithium iodide battery to work. A natural human cardiac pacemaker doesn't require a battery. That said, if you had a real person and completely identical biological doll (with natural heart, natural neurons, natural nervous system, etc.), the doll still wouldn't start to generate cardiac pacemaker impulses by itself (to start the heart and subsequent vital processes, specifically to eat and drink to provide energy for neural action potentials) and would require some kind of battery, as in artificial pacemakers (unlike humans). Is such inference actually valid in scientific terms? Brandmeistertalk  15:42, 9 March 2015 (UTC)
 * That's an outdated view. We have known for quite a while that many parts of the brain and body are spontaneous oscillators -- particularly the heart.  If the heart is healthy, it doesn't need any external signal to start, it will just start automatically.  The function of a pacemaker is not to keep the heart going, it is to control the timing of the beats.  Even during a heart attack the heart doesn't stop beating for a long time -- what happens is that different parts of the heart lose synchrony with each other, and the muscle contractions become disorganized, resulting in a failure to pump blood properly.  (The idea that you're suggesting here, by the way, goes back to the ancient Greeks.  Aristotle argued that the difference between living and nonliving things is that living things move themselves whereas nonliving things require something external to start them moving.) Looie496 (talk) 16:02, 9 March 2015 (UTC)


 * Humans don't develop from unliving dolls like Frankenstein's Monster needing a jolt of electricity. The life in your body is continuos with that of all life on earth, human eggs or the germ line being no different in essence from single-celled organisms.  Some cells die, but all cells come from prior life.  That being said, the ability to produce an action potential just depends on a cell's expressing its genes to create various ion pumps and gates which work spontaneously or when triggered.  There's never any dead state from which these cells need to be aroused by ensoulment.
 * Yes, but an action potential is not necessarily a response to an external stimulus, it may spark arbitrarily (for instance, in humans to simply walk back and forth without any physiological need). In other words, a neural action potential doesn't seem to be generated by an organism itself. And of course, there are many other examples, where action potentials are not triggered simply to sustain biological functions, such as creative work (arts), etc. Consider, for instance, holding one's breath. The related action potential would not be triggered by an organism itself because it's obviously detrimental to it and after some time your will would be overridden by involuntary inhalation. That's why a person wanting to commit suicide can't kill oneself simply by holding his/her breath and choking by hands, which (in my view) indicates the presence of an independent incorporeal agent within body. I wonder whether this may be regarded as prima facie evidence for soul. Brandmeistertalk  16:26, 9 March 2015 (UTC)
 * Arguing this in detail is possible - but tedious in the face of someone who clearly doesn't want to believe it. However, I'd like to point out how simple it is to program a computer to do all of these things - and (presumably) you'd deny that my cellphone has a soul. SteveBaker (talk) 18:07, 9 March 2015 (UTC)


 * Brandmeister, you appear to be proposing just another twist to the old Dualist position, with somehow (?) action potentials acting as a missing link between the body and soul. A useful review of the history of such ideas, and their current (discredited) status, can be found in the writings of, say, Patricia Churchland (Brain-wise and Neurophilosophy) or Daniel Dennett (Consciousness explained). Read them if you are interested in learning more. Abecedare (talk) 19:06, 9 March 2015 (UTC)


 * (Personal comment, perhaps rambling, sorry:) Action potentials occur in the isolated neurons of sea slugs, in cardiac myocytes differentiated on a tissue culture dish, indeed, in isolated pieces of cell membrane in a patch clamp procedure.  They are a poor choice for finding the soul.  Understand that one can suppose a sufficiently advanced robot acts in a way that perfectly duplicates the actions of someone with a soul; you cannot tell by looking whether it is present or absent; it has no direct physical consequence.  Therefore, a soul is a paranormal phenomenon, and one should look for a paranormal explanation: specifically, I'd say one should look for methods by which causality violation can be induced, then think on how new boundary conditions of the cosmos can exist in the present space and time, and what they mean. Wnt (talk) 19:16, 9 March 2015 (UTC)
 * I still see a missing link in the scientific approach. While the said pacemaker impulse, for example, originates in genetic instructions during gestation, where does the action potential for holding one's breath ultimately come from? Brandmeistertalk  20:02, 9 March 2015 (UTC)


 * For the sake of argument, let's propose that you are right and the soul somehow influences neuron action potentials. How is that different from the hypothesis that action potentials are simply an entirely natural manifestation of physical and biological processes?  Under what circumstance would the soul hypothesis predict different results than the biological hypothesis?  Are there experiments we can do in a laboratory with cultured neurons?  Or maybe in animals, do they have souls that influence their behavior?  If only humans are posited to have souls, then how do we see that difference in our own brains?  If there is no situation where the influence of a soul can be observed and distinguished from a purely biological process, then invoking a soul as an explanation is at best a non-scientific idea.  Many people have faith in non-scientific ideas, and such ideas often give them comfort, but it isn't generally rational to take non-scientific ideas and expect to find scientific justifications for them.  Dragons flight (talk) 20:41, 9 March 2015 (UTC)
 * It's fairly well known that basically there are two kinds of action potentials: those controlling involuntary actions such as heart beating and those mediating control over voluntary actions, like the said voluntary control of respiration. In other words, there's a clear distinction between what an organism can control by itself and what it cannot control by itself. Also, during disorders of autonomic nervous system, which controls involuntary processes, people can sense that something is not normal by themselves, i.e. during urinary incontinence, erectile dysfunction, etc. Now, per action potential, the voltage-gated ion channel generate a potential when they rapidly begin to open if the membrane potential increases to a precisely defined threshold value. What causes the membrane potential to increase to a precisely defined threshold value when holding breath, for example? That still evades me, unless soul is invoked. Brandmeistertalk  21:36, 9 March 2015 (UTC)
 * The sum of all your prior observations, preferences and decisions produce that action potential. You smell smoke, you don't like the smell, you figure you can cross the area quickly enough that you won't need to breathe.  All this depends on prior action potentials and neural connections, your development since conception.  It's action potentials all the way down.  To paraphrase Christopher Hitchens in his last book, You don't have a body, you are your body. μηδείς (talk) 01:15, 10 March 2015 (UTC)


 * If you are interested in breathing specifically, you might be interested in control of ventilation which discusses some of the underlying physical processes. The beating of a heart is fully automatic.  Moving my arm is voluntary.  Breathing is really in a third category, automatic processes that can be voluntarily modified.  In general, breathing is an automatic process most of the time.  We don't have to actively think about it, and it continues if a person is asleep, unconscious, or loses higher brain function.  However, we are also able to consciously intervene and hold our breath (in principle until one passes out, though I don't recommend trying that).  Animals also can hold their breath, most notably when swimming, but also in other situations.  Aside from being in the middle ground between automatic functions and voluntary ones, I'm not sure why you feel breathing is special, or what role in breathing you are assigning to a soul.  In your view, is the soul what keeps us breathing or what allows us to hold our breaths or what?  Conscious choice (or the illusion of choice) is still a fairly mysterious thing, but that extends to all voluntary behavior.  I'm not sure why holding one's breath is special in that regard.  Dragons flight (talk) 01:41, 10 March 2015 (UTC)


 * He seems to be asking what is the prior cause of the action potential that overrides the normal breathing process and causes the breath to be held. Again, it's simply a sum of prior action potentials signaling the presence of smoke, fear or dislike of it, and prior experiences over the years which have caused certain neural pathways to develop leading up to this point.  Holding you breath as you drive past a pig farm is not something that suddenly happens just then, it required two decades of physical development from an egg, and all the experiences and decisions that have been made over the years to set up your brain so that it is capable of making this choice at this time.  There is no special intervention at any point.  Nor is there really any such thing as an instant--that's a complex abstract idea that we have that allows us to imagine that at one instant "we" as opposed to "our bodies" made a decision.  There is no such instant, just a constant flow, and just as we are our bodies, we are also our individual pasts.  A choice is not an instant without a physical cause, it's just a hugely complex event that is a result of your entire history. μηδείς (talk) 04:52, 10 March 2015 (UTC)
 * Yes, again, just to clarify, I'm specifically asking about an action potential originating without prior stimulus at any given time, like the said respiration control at any given time without external stimulus (no unpleasant smell, smoking, etc) or simply moving one's hand or leg arbitrarily, or whatever body part we stupidly wish. Btw, while unconscious normal breathing is controlled by brainstem, the action potentials to hold one's breath come from another source, cerebral cortex. Brandmeistertalk  09:13, 10 March 2015 (UTC)
 * There's no such thing. There may be some cause internal to the cell that makes it fire "spontaneously" from an outside perspective when some threshold is met inside the cell. At no point is there anything that doesn't happen as a result of the arrangement of the chemical parts of the cell, which is a result of prior causes, prior external stimuli and the expression of certain genes within the cell. If you are going to continue asserting there are certain action potentials that have no physical cause at all you are going to have to prove it. μηδείς (talk) 21:52, 10 March 2015 (UTC)

Power needed for a 4-inch fan
How much power is needed to run a 4-inch fan?. The fan is to be used for venting air from a small bathroom, and has only one speed. Bh12 (talk) 15:50, 9 March 2015 (UTC)


 * Turning the fan requires torque (i.e. a twisting force). The article on Torque describes the relationship between torque, power, and energy, as well as different ways to calculate torque. Note that power is work done over a certain amount of time: you'll need to determine what time period you're interested in; if (as I suspect) the fan is powered by electricity, then Kilowatt_hour is a commonly used unit. OldTimeNESter (talk) 16:30, 9 March 2015 (UTC)


 * Hopefully the device either has a wattage rating or amperage rating written on/engraved in it. If they gave you the amps, just multiply that by your voltage (usually either 110-120V or 220-240V) to get the watts, then multiply by the time used, in hours per day, to get the kilowatt hours used per day.  Here's a calculator that accepts common units: .  If the device is labelled with units not mentioned there, lets us know, and we can help with the conversion.  If the device lacks any specs whatsoever, you may need to get a Kill-A-Watt meter or equivalent, which will tell you the wattage directly. However, if the fan is hard-wired in the wall, that won't work.  In that case, try looking up similar fans online to get their wattage ratings. StuRat (talk) 16:56, 9 March 2015 (UTC)

Let me be a bit clearer: Stores sell 4-inch fans for the purpose I described above - what would be a typical power rating for such a fan? 1 watt? 10 watts? Wattever? (please pardon the pun...)Bh12 (talk) 17:19, 9 March 2015 (UTC)


 * This one is 3 watts: . (Be careful when searching, because I found many larger fans which squeeze the air into a 4 inch duct.)


 * I'm also shocked at the price. Why should a 3 watt, 4 inch, 1 speed fan, made in China, cost almost $300, when I get a 100 watt, 17 inch, 3 speed box fan, also made in China, for $15 ?  At that price I suspect the purchase price of the fan will be far more than the energy usage cost, over the lifetime of the product.  StuRat (talk) 17:37, 9 March 2015 (UTC)

Thank you!

Global warming experiments.
I can prove gravity by dropping a ball. I can prove Einsteins theory's by taking a photo of the misplaced stars during an eclipse. I can weigh the earth using a Cavendish torsion balance. I can prove the rotation of the earth with a Foucault pendulum.

I can prove global warming by.... — Preceding unsigned comment added by 86.177.220.245 (talk) 19:03, 9 March 2015 (UTC)

By dressing like this in the summer. Count Iblis (talk) 20:14, 9 March 2015 (UTC)


 * Lots of ways!


 * Launch a satellite that uses radar to measure it's average height above the oceans, collect this data over a decade or so and plot a graph showing sea level as a function of time. If you do that, you'll see it going steadily upwards indicating that the water is expanding due to it's increased temperature.


 * Distribute a few hundred thermometers around the globe and take readings from them about once a month for several decades and plot graphs of what they read. Note that the average of their readings is going steadily upwards.


 * Photograph glaciers and ice at the poles every year for several decades and plot graphs of the area of snow and ice over time.


 * ...well, I think you get the idea. The problem is that we're looking at a long term trend - and to expect a single experiment, performed over a day or two, to demonstrate this is entirely unreasonable.  So unless you have the funding, the skills, and the patience, to undertake these very long term, rather costly, experiments - it's hard to distinguish the subtle long-term climatic changes from the day to day effects of random weather.


 * That said, there are tests you can make with ice-cores cut in the antarctic that demonstrate year-on-year pollen grain deposition and ice accretion thicknesses that could be done and analysed fairly quickly...but still, it's not something that exactly easy.


 * You're probably going to argue that you don't trust the people who have done all of those experiments - yet, for some bizarre reason, you DO trust that the ball moves downwards when you release it because of "gravity" - when you could equally suspect that the earth is growing in diameter at an extraordinary rate and that you're feeling that acceleration.  There are people (nut jobs, admittedly) who believe that (http://www.circlon.com/living-universe/015-cause-of-gravity.html for example) - and when you try to disprove it, they simply refuse to accept the evidence provided by more indirect means.   If you're hell bent on disbelieving a scientific theory and if you're perfectly happy to discard all of the mountains of evidence produced by large-scale experiments for whatever half-assed reason - then I don't think you should accept either gravity, relativity or the weight of the earth since all of the 'experiments' you described are built on previous work, which you ought to doubt if you doubt the experiments that confirm climate change.


 * What's most significant about all this is that all of the independent ways to determine that the planet is warming up faster than anything other than man-made intervention could produce...all of those experiments agree with each other to a remarkable degree.  If we were just seeing glaciers retreat - then maybe we could find other explanations - but the fact that they are vanishing, and sea levels are rising and our weather is getting wilder and the number of tornadoes is going up and we have historic levels of drought in some parts of the world and...yadda yadda...means that we have to dismiss all of those studies - and over the last 20 years, the evidence has just been piling up, higher and higher - to the point where disbelieving it is an act of willful ignorance - self-deceit - wishful thinking.


 * If you truly need a single, simple experiment - then go find a glacier - take a photo - come back a few years later and take another photo...compare the two...it's not a perfect proof - but then neither is watching an apple fall from a tree proof of gravitation.


 * SteveBaker (talk) 20:34, 9 March 2015 (UTC)


 * and if you did that in New Zealand you'd find glaciers are growing, not shrinking. Greglocock (talk) 22:56, 9 March 2015 (UTC)


 * That's odd I looked at http://en.wikipedia.org/wiki/Envisat and http://en.wikipedia.org/wiki/Jason-1  and there seems to be a discrepancy in the measurements for sea level rise. I suppose that means that I am insane for questioning it or something..  — Preceding unsigned comment added by 86.177.220.245 (talk) 22:43, 9 March 2015 (UTC)


 * Unfortunately sea levels are increasing in some places and decreasing in others (be careful of datums) . There may be a global tendency to rise, but then you'd need to account for a lot of other variables before you can be sure. None the less, I think there is good evidence that the earth is growing warmer on some timescale, since we are coming out of an Ice Age. On the other hand as Greenland's ice retreats it reveals farming communities from ~1000 years ago, indicating that perhaps the effects aren't quite as simple as the worry warts would have it. Of course most of the fuss is about whether CO2 is a significant contributor to global warming, which seems to rely on computer models of spectactular complexity and ineptitude.Greglocock (talk) 22:56, 9 March 2015 (UTC)
 * I gather you're falling for the good old "Greenland used to be green" story. Sounds good but not true. According to the sagas Eirik the Red gave the colony its name not because the land was green, but because he thought an attractive name would induce people to go there -- in other words advertising hype, 985 AD.  Can you give any examples of Norse farms that have emerged from the ice?  There's Garden under Sandet, but that was buried under alluvial sand (hence the name) rather than ice. Short Brigade Harvester Boris (talk) 04:13, 10 March 2015 (UTC)
 * Cherrypicking data gives you any result you want to hear, or promote. Such as glaciers in NZ are growing. if you pick one of the 10% that are growing, sure, while ignoring the 90% that are shrinking. That's similar to the percentage of scientists who support most of the findings of the IPCC. Such a unilateral consensus in science is actually rare, I wonder what "insight" someone like Greglocock has that he can so easily and flippantly dismiss 90% of the scientists on earth? Ignoring that 2014 was globally the hottest year on record; that we've had 38 consecutive years of above average temperatures; ignoring even the temperature trend in New Zealand. Vespine (talk) 05:22, 10 March 2015 (UTC)
 * See also Retreat of glaciers since 1850 and . There's also these rather famous examples   . What makes both Fox Glacier and Franz Josef Glacier particularly funny is as per the various articles including ours, I'm fairly sure both was used as a key examples of NZ's growing glaciers. Whoops.  (And if I'm getting the dates right, that's from after they started shrinking again. Double whoops.) I would however agree that these examples show why it's unwise to cherry pick data or choose only a specific example. Nil Einne (talk) 05:41, 10 March 2015 (UTC)

Shrugs, Jared diamond : http://www.newyorker.com/magazine/2005/01/03/the-vanishing-2 - these settlements were obvioulsy farmable/if not sustainably/ at the time, and have recently been uncovered (I think). Anyway, sorry for spooking the hive-mind, I'm quite sure your computer models will continue to reassure you. I am fully aware most glaciers are shrinking, and I agree, the earth is generally warming as we emerge from an Ice Age, My point was that single point experiments aren't much use in isolation. Greglocock (talk) 10:22, 10 March 2015 (UTC)
 * Have you read the article you linked to? There is nothing about "recently uncovered" (by ice) there. Sites like Brattahlíð have never been covered by glaciers since the time of the vikings, and we have known about them since the time of the sagas. Gladwell's exposition of Diamond explains the downfall of the Norse settlements in Greenland (and the reduced greening) not by any change in climate, but by over-harvesting of wood, overgrazing of meadows, and the resulting soil erosion, which destroyed the foundation of local agriculture. There probably was some temporary shift in local climate as well, but that's not in your source, it's over, and it was much less dramatic than you seem to suggest. --Stephan Schulz (talk) 10:49, 10 March 2015 (UTC)


 * On 'None the less, I think there is good evidence that the earth is growing warmer on some timescale, since we are coming out of an Ice Age', actually we should probably already be entering another ice age given the pattern in the last couple of million years. There's dispute over that like anything to do with climate but the last ice age ended about 10,000 BC and as far as I can see the evidence leans towards that it should have started getting cooler but human activity has reversed that. Dmcq (talk) 17:39, 10 March 2015 (UTC)


 * The point here is that this is a long-term, global climate change. Every one of those words are important.  You can't measure the temperature on Feb 20th in Milwaukee on four consecutive years and decide that we've had a bunch of bad winters in a row, so the world is cooling.  You need to measure over the entire planet ("global") and over decades ("long-term") - and you're looking at climatic changes (very broad effects) and not local weather differences.   One or two glaciers may well be growing - but if most of them are shrinking, and have been doing so for a decade then the global answer is that "glaciers are shrinking" - and that's what we care about.  A few bad winters or crazy hot summers in a few places in the world would be no surprise and probably no cause for alarm.  But a world-wide (average) change that's sustained (statistically) over decades is decidedly terrifying.


 * This point is underscored by these 'polar vortices' that are hitting North America repeatedly this year and the last. If you happen to live there, it looks a lot like the world is cooling - but that's because the normally stable airflow around the arctic is being disrupted by a global pattern of temperature increase - causing that "polar vortex" to start to spin out of control.   Locally "weird" weather is perhaps another symptom - but measuring it that way doesn't work.  You need global measurements over decades to see this unmistakable trend.


 * SteveBaker (talk) 17:43, 10 March 2015 (UTC)


 * If you want one experiment respecting global anthropogenic climate change, then the most famous individual experiment is probably the NOAA measurements of monthly mean atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii. This is a famous, decades-long measure of carbon dioxide concentration (not temperature).  In isolation, it is not sufficient to prove very much at all.  But, it is the most famous experiment because the data product is easy to visualize; because the signal-to-noise ratio is very high; because the quality and integrity of the measurements are excellent.  This experiment is often cited in other literature.  The data is correlated to temperature.  A causal hypothesis exists and can be tested against the data.
 * If you're going to nitpick the data, or even if you are going to extoll the virtues of the science, it is a good idea to familiarize yourself with the most famous experiments. Another excellent source of reading-material is the IPCC Climate Change Report 2015, which reviews almost all present scientific efforts related to this area.
 * Nimur (talk) 17:57, 10 March 2015 (UTC)
 * I'm well aware of the Mauno Loa observations, but would you really call it an "experiment"? Certainly not a controlled experiment, as we only have one Earth... perhaps OP is a little confused, and is looking for a way to establish global warming via a rigorously controlled experiment -- and that is not available. "Natural experiment" is sometimes used for this sort of thing, e.g. the industrial revolution didn't set out to test the notion that pumping CO2 into the atmosphere would warm the planet, but our observations indicate that is indeed the case. OP may also be interested in the distinction between anthropogenic climate change vs. a general warming trend. The latter is easier to establish, but even the form has overwhelming evidence, we just have to be a little more careful how we structure the arguments. SemanticMantis (talk) 19:34, 10 March 2015 (UTC)
 * Indeed. NOAA's webpage does not actually call this series of observations an "experiment."  They call it a "data set."  Nimur (talk) 19:56, 10 March 2015 (UTC)


 * There are plenty of sciences where experiments in the classic sense are impossible...cosmology, astronomy - for example. Take the Einstein 'experiment' of testing relativity by looking how the sun bends sunlight during an eclipse.  The "experiment" was to wait for an eclipse and measure how much the light was bent.  But if there had been a bunch of high resolution photographs of the stars close to the sun from previous eclipses ("data") - then it would have been equally valid to go back and look at that historical record to see if light bending was demonstrated in those photos.  SteveBaker (talk) 04:33, 11 March 2015 (UTC)


 * Question to the OP: if you already know the answer, why are you asking us? Asking a question implies some willingness to accept the answer, or at the very least, some attitude other than condescending arrogance.  If your only purpose is to be polemical, this isn't the place for you.  --Bowlhover (talk) 18:27, 10 March 2015 (UTC)


 * To be honest, I was simply asking a question (Like Feynman, I like to ask simple questions to which I don't know the answer for). There seems to be an EMOTIONAL quality to peoples responses to this issue . The first thing I picked up was a discrepancy from the satellite data for the sea level rise. Jason-1 says 3mm a year and ENVISAT 0.5mm a year. This is a fact that should be looked into instead of being shouted down as irrelevant. I want a green planet like everyone else..who doesn't? I am genuinely interested in the science but hate been called a DENIER as soon as I ask a skeptical question.  — Preceding unsigned comment added by 86.177.220.245 (talk) 18:05, 11 March 2015 (UTC)
 * I didn't see very much emotional about the answers above, you are the only one using capital letters for instance and no-one said you were a denier so I would say you are the most emotional and are simply projecting your feelings on others. As to sea levels there can be local variation, for instance the average sea level for the last couple of years on the east coast of America was higher than the average global rise due to climate change, this is due to a change in currents in the Atlantic which happens every so often . Dmcq (talk) 19:58, 11 March 2015 (UTC)


 * The thing is that you can find small discrepancies in any very large data set - but that doesn't allow you to disregard the whole thing. Sure, if those two sea level studies come out with 3mm and 5mm as their answers, then you don't know what the actual rise is - but you can say with fairly high confidence that the sea level is rising and not staying the same or falling.  Add that to the other studies about sea level change - and that adds further weight - then look into ocean temperature studies, and those are showing an upward trend too...and on, and on, and on.  Since few (if any) of the significant studies show a trend in the opposite direction - it is an overwhelmingly clear that we must say "The planet is warming and mankind is the cause".   Now, when you come to ask whether some specific city is going to be overwhelmed by the ocean on some particular future date - then the issue of whether the ocean rise is 3mm or 5mm starts to become of paramount importance.   Just how long will it be before New York needs a flood barrier like the one London has?   The degree of uncertainty in the numbers makes that prediction difficult - and doubly so because we have to include the (increasingly remote) possibility that everyone will come to their senses and start working to fix the problem.   So make no mistake, there is certainly doubt and controversy about the magnitude and imminence of the problem - but there is really zero doubt that it's happening.


 * Another thing to be concerned about is the risk involved here.  The utterly disasterous consequences of assuming that climate change is not occurring, despite all of the experimental data, are pretty extreme.   We might lose the planet - we could definitely see the end of civil society and great civilizations - and we'll most definitely cause ungodly amounts of environmental damage.   On the other hand, if we assume that climate change is real - and against all odds, it's not - then we'll have spent perhaps 10% of GDP on fixing a bunch of things that needed fixing anyway.  The potential loss we assume that climate change is happening is absolutely humungous compared to the loss if we assume that it's not happening, when in fact it is.    So if there were any shadow of doubt whatever about the answer here - either way - then we should still mobilize humanity to fix it.


 * As for the emotion...you must understand that people here on this science reference desk are overwhelmingly interested in the answer that science provides - which is that climate change is real.  We very often get people coming here seeking to push the skeptical position - and it's unsurprising that we're going to be a bit on-edge when that happens.   I know that I won't live long enough to be terribly inconvenienced by climate change - but I also know that my son most certainly will feel the effect - and our four grandchildren may well find themselves in a terrible, irrecoverable disaster that will utterly ruin their lives.   That degree of importance makes me want to take each one of these (frankly, idiotic) deniers firmly by the throat and beat the freaking obvious facts into their dumb-assed skulls until they understand the importance of what we now know.


 * In your case, it's tough to understand your interest in a single, simple, fundamental experiment that would undeniably show that there is or isn't a problem.  I've heard very many of the nut-job deniers (eg members of the US Republican party) use exactly this argument ("There is no experiment anyone can do to prove climate change") as a way to carry on the way we are.   It's an absolutely stupid argument, because (as I've tried to point out), this is not a problem that can be investigated in that way.   The very nature of a slow effect that produces only an average change when you examine the entire planet means that such a single, simple experiment is impossible...but that in no way means that we don't know the answer...we certainly do.


 * It's worth pointing out, again, that not one of the experiments you described as being of the simple, easy, conclusive kind are actually anything of the sort.  Every one of them relies on a huge mountain of knowledge that had to be acquired before the conclusion could be arrived at.   For example, the bending of light by the sun, demonstrating the truth of Einsteins theory of relativity...I might (as a skeptic) suggest that the sun's atmosphere might extend out far enough to cause refraction of the light through it.   OK...so tell me again how your experiment proves relativity?   It only does so because we know about the sun's atmosphere and about how light is refracted by it.   And your complaint about those two satellites showing differences in the sea level rise is precisely mirrored in the different angles calculated for the light bending by the two teams who set out to measure it.  They could only say that the amount of light bending was NOT INCONSISTENT with Einsteins finding - and too much to be explained by the previous prevailing theories.   Same deal with the ocean rise.  The two increases noted are NOT INCONSISTENT with global climate change - and are too much to be explained by "situation normal" variations.   Science rarely proceeds with absolute, perfect experimental results - yet, by collecting statistically valid spreads of results, we've been able to put together all of the astounding amounts of technology that allows you to read this post.  Science works....it truly does...even when there isn't a single, clear result but only a gigantic mountain of slightly fuzzy results that all point in the exact same general direction.  SteveBaker (talk) 20:38, 11 March 2015 (UTC)


 * Envisat shows 0.5mm rise, not 5mm rise. — Preceding unsigned comment added by 86.177.220.245 (talk) 22:19, 11 March 2015 (UTC)
 * ¿Que? Short Brigade Harvester Boris (talk) 12:18, 12 March 2015 (UTC)
 * If you want to quibble over such a detail - and it's fine if you do ... plenty of us here love quibbling over technicalities! We're volunteering our time to read and discuss long boring scientific reports! - at the very least, please cite a source!  Who showed this data?  What exact result did they present?  When did they show it?  Where did they publish their findings?  Why did you feel like you could post a specific scientific fact without a reliable source to back it up?
 * Here is Envisat's webpage from the ESA. As you can see from the photographs, Envisat is an observation satellite, and as such, it is an inanimate object incapable of actively demonstrating any scientific premise. Furthermore, it has been missing in action (or at least AWOL) since 2012.  Perhaps you are misattributing the work of some human scientist to this satellite.  The complicated process of analyzing archived satellite data is not commonly performed by inanimate scientific equipment.  Nimur (talk) 13:50, 12 March 2015 (UTC)


 * http://en.wikipedia.org/wiki/Envisat#RA-2 — Preceding unsigned comment added by 86.177.220.245 (talk) 22:33, 12 March 2015 (UTC)
 * I've actually looked at the linked chart in the article and I really can't figure out what data points was used to reach that number in the "first eight years" of the mission. Thar said, if you ignore the overall trend I'm sure it's possible to cherrypick some combination of data points to show that the sea level is rising by 0.5 mm/year, or rising by 50 mm, or sinking by 10. However, if you look at the overall trend it shows that the level is rising by about two and a half mm per year. I've removed the statement about 0.5 mm from the article as it is one editors own synthesis and not supported by a reliable source. Sjö (talk) 10:22, 13 March 2015 (UTC)


 * There's no direct correlation between average temperature and snow cover or glaciation. Imagine an idealized world with two seasons, each with a constant temperature.  In the first the summer will be a constant 60F, while the winter will be a constant 40F, hence a year-long average of 50F, but no snow, because it never drops below freezing.  Then, imagine a climate with 70F temperature in the summer, and 30 all winter long.  This climate will also average 50F, but with significant snowfall.  Then imaging a climate with 85F summers, and 25F winters.  This climate will have a 55F average temperature (Global Warming!) but its summers will produce a lot more humidity than the 70/30 climate, and produce more snowfall when winter comes.  The idea is paradoxical, but standard climatological thinking.  See After the Ice Age: The Return of Life to Glaciated North America, by noted Canadian ecologist E. C. Pielou, who argues that we are already entering the next glacial period. μηδείς (talk) 01:15, 13 March 2015 (UTC)

Spec/Glass
Hello,

Has anyone seen the eyes of the mask in the Movie: The Amazing Spiderman? It’s from a spec I forgot the name of. I wrote many rubbish in the google and unable to find even an image of it.

Description: The spec does not have a glass in its glass holder frame, it has a plastic kind of thing with many little holes in it.

Does anyone know the name of the spec/glass?

(SuperGirlsVibrator (talk) 21:52, 9 March 2015 (UTC))
 * I'm not sure that I understand your question, and I haven't seen the movie; but are you referring to something like pinhole glasses? Deor (talk) 23:48, 9 March 2015 (UTC)
 * Yep! I've looking for this for few years! Thank you! -- (SuperGirlsVibrator (talk) 07:26, 10 March 2015 (UTC))