Wikipedia:Reference desk/Archives/Science/2012 July 18

= July 18 =

were the apollo missions classified
if not, why not open source all the designs. — Preceding unsigned comment added by 84.3.160.86 (talk) 00:34, 18 July 2012 (UTC)
 * Seems to me this issue came up some years back at the Moon Hoax page, and some editors there discovered that the designs weren't necessary kept in perpetuity. ←Baseball Bugs What's up, Doc? carrots→ 01:34, 18 July 2012 (UTC)
 * Certainly some aspects of the Apollo missions were classified, but that's not the only reason why any particular aspect of the missions, like the designs, might not be made available to the public. Another reason might simply be that it isn't in their interet. Why would they make the designs available to the public? Vespine (talk) 01:38, 18 July 2012 (UTC)
 * Because it's the law?A8875 (talk) 01:51, 18 July 2012 (UTC)


 * There is an urban legend that the plans for the Saturn V rocket no longer exist. The paper copies were destroyed when they were no longer needed but they still exist on microfilm.  As far as the other Apollo hardware, I don't know what happened to the blueprints.  They might have been destroyed when they were no longer needed.  Bubba73 You talkin' to me? 01:56, 18 July 2012 (UTC)


 * "Because it's the law"? The article linked seems to refer to copyright. Even if NASA was covered under this (which is by no means self-evident from the linked article), all it would amount to saying would be that if anyone got hold of the relevant details, it wouldn't be a breach of copyright to publish them - or presumably to use them to build your own Saturn rocket. How would this non-copyright status amount to an obligation to actually provide the details to anyone in the first place - assuming that they still have them? AndyTheGrump (talk) 02:14, 18 July 2012 (UTC)
 * Works by NASA are in the public domain, but that doesn't mean they need to go out of their way to make everything publicly available on the internet. No one has those kind of resources. - Running On Brains (talk) 15:43, 18 July 2012 (UTC)


 * I don't know anything about the mechanical aspects, but I do know something about the electronics that have been used in the space program, and if they are typical, then there wouldn't be anything worth open-sourcing. NASA has been so conservative in its engineering that components were generally ten years out of date by the time a mission flew.  Given how long it's been since the Saturn V missions, I shudder to think what you would see there.  It would be like open-sourcing stone tools from the Neolithic. Looie496 (talk) 02:25, 18 July 2012 (UTC)


 * And following on from that, much of the hardware might simply no longer be available. Certainly the electronics, but I'd suspect much else besides. I don't think that there is much that is actually 'non-public-domain' in terms of the information you'd need to build a new 'Saturn equivalent' design from scratch - and it would probably be simpler than trying to reproduce the original technology exactly. I suspect that more modern technology would make a better system anyway: lighter/more powerful electronics, composite materials, and all the advances in CAD/CAM manufacturing would surely improve performance a little - though perhaps not a great deal, since basically a Saturn rocket before launch is mostly fuel and oxidiser by mass, and that won't change. AndyTheGrump (talk) 02:43, 18 July 2012 (UTC)


 * Not saying directly whether or not the designs are or are not classified, but if they were, one could certainly understand why they would be, and why they would still be, and it has nothing to do with covering up a moon hoax. The Saturn family of rockets were designed for putting people into orbit, but it would take much modification to make them into a perfectly functional ICBM, capable of reaching any place on Earth.  The U.S. government has a vested interest in keeping such information on the QT.  -- Jayron  32  03:31, 18 July 2012 (UTC)


 * Are you saying the Apollo/Saturn plans are not open-sourced? Just my opinion, but I tend to believe if you sought out plans, you could obtain them. Plenty of people have built working replicas of the Apollo CM guidance computer, possibly the most sophisticated piece of equipment on the spacecraft. The computer plans are easily found online. (see here) The rest of the technology used on the spacecraft is far less advanced, and in the 21st century almost all of it is obsolete.  → Michael J Ⓣ Ⓒ Ⓜ 03:44, 18 July 2012 (UTC)


 * It was impossible to obtain some specifications of the Saturn V and related guidance systems at the time, and a few of those are probably still classified, but pretty much everything else was out in the open. You can certainly obtain blueprints which are very accurate but omit avionics -- that was one of NASA's most popular FOIA requests for years. You can obtain the Moon landing computer design and program, but not the launch avionics computer programs (digital and analog) for the Saturn V Instrument Unit's computers. The astronauts were often consulted as to how much of their private lives (i.e., medical and duty condition) would be shared with the press, and of course they all wanted pretty much everything out in the open, too. 75.166.200.250 (talk) 04:03, 18 July 2012 (UTC)


 * You can find source code from the Apollo missions here. -- BenRG (talk) 05:49, 18 July 2012 (UTC)


 * ITAR will make it complicated to gain access to the technical stuff which is not already available. Every drawing or schematic for hardware used in space is now ITAR restricted. Even giving the name and the type of plug used to connect Mars Science Laboratory parts is only allowed after checking with if it violates ITAR. The WWW is international and therefore putting the drawings onto the net will make you a target for homeland security.--Stone (talk) 10:09, 18 July 2012 (UTC)


 * The Apollo Guidance Computer is well-documented. Not just the source code listed above, but the whole system. People have built replicas. 209.131.76.183 (talk) 11:41, 18 July 2012 (UTC)


 * How does ITAR apply to the Apollo program? NASA is a civilian agency, not military.  → Michael J Ⓣ Ⓒ Ⓜ 11:59, 18 July 2012 (UTC)
 * ITAR is a list of things. Dual use items are on that list too. The classification of all material used in space as significant military equipment is written in the documents. It does not make sense but it is fact. Talk with people from Mars Science Laboratory is very annoying because at that time no TAA (Technical Assistance Agreement) was in place and therefore the only things presented were things already published or general knowledge. The point is different for US Citizens, but the rest of the world is not allowed to get access. --Stone (talk) 12:53, 18 July 2012 (UTC)
 * is a little story within NASA about ITAR. --Stone (talk) 12:56, 18 July 2012 (UTC)


 * Was the technology classified? Yes, but not to a very high grade. A brief perusal of NASA Apollo documents shows that many of them have classification stamps on them: a CONFIDENTIAL description of the spacecraft from 1963; CONFIDENTIAL mission description from 1961; CONFIDENTIAL report of some kind from 1961; CONFIDENTIAL mission directive from 1961; CONFIDENTIAL study of moon landing modes from 1962; and so on. I haven't seen anything higher than CONFIDENTIAL, which is the lowest official ranking of classification you can have (it goes CONFIDENTIAL, SECRET, TOP SECRET, more or less; OFFICIAL USE ONLY is a rung below CONFIDENTIAL but is not really a legal classification category).
 * So that's pretty weak classification for mission-related things. The rocket technology itself was no doubt classified higher than that, because, as others have mentioned, it was (and is) dual-use technology, and because the US was, you know, engaged in a big Space Race with the ol' USSR. Mission details were likely CONFIDENTIAL just to avoid the possibility of sabotage, or giving away programmatic information on the US space effort. The low level of classification is meant to signal that even if they got out, it wouldn't be that big a deal; it also meant that the information could be widely shared within the NASA organization.
 * As for open-sourcing at the time, the reason you wouldn't do that is because the Cold War US model was "buy all the experts and give them gobs of resources," which gets rid of the need for open-sourcing. (Plus, this is rocket science. It's actually hard. Even when you do the "throw everything at it with the most brilliant people at your disposal" approach, your rockets still blow up on the launch pads half the time.) As to whether you could do it today, sure! In theory. But it takes a lot more to build a moon shot in theory than a bunch of people editing a Wiki. It's a Big Project, much harder in terms of technical accomplishment than, say, designing an atomic bomb or something like that. --Mr.98 (talk) 13:42, 18 July 2012 (UTC)

Pluto / Charon satellites
If one considers Pluto and Charon to be binary planets (rather than Charon being a satellite of Pluto), then how do the satellites Hydra, Nix, P4 and P5 relate to the double system? Do they orbit the same barycenter, or are they satellites of just one or both of the planets, or what? (Yes, I know what the IAU ruled in 2006; I simply disagree.)  → Michael J Ⓣ Ⓒ Ⓜ 07:34, 18 July 2012 (UTC)




 * They all appear to orbit it's barycenter. I don't think it would be possible to orbit just one or the other, and have it be a stable orbit, unless, perhaps, the orbit was in a Lagrange point (and, even then, it's technically orbiting both). StuRat (talk) 07:38, 18 July 2012 (UTC)


 * Contrary to popular belief, it is possible to have a stable orbit around just one member of a binary pair: see Binary star. --Carnildo (talk) 22:38, 18 July 2012 (UTC)


 * I can't see how this question would be any different for the orbit of all the planets about the Sun. It too is affected by the other planets, and wobbles for each one. The wobbles must all be added up and come to one rather complex wobble. Myles325a (talk) 07:47, 18 July 2012 (UTC)


 * True, but then every object in the universe could also be said to be wobbling due to in orbit about every other object. The difference is, in the case of Pluto and Charon, it's visually obvious that they are orbiting the barycenter. StuRat (talk) 07:50, 18 July 2012 (UTC)


 * Are the galaxies orbiting around anything, or are they flying away from wherever the Big Bang supposedly occurred? ←Baseball Bugs What's up, Doc? carrots→ 11:23, 18 July 2012 (UTC)


 * The Big Bang occurred everywhere. And Stu's statement is not usefully true, but only trivially. So yes, any galaxy is 'in orbit' around any other - but most of the orbits are wildly unstable! AlexTiefling (talk) 11:34, 18 July 2012 (UTC)


 * This is untrue, unless you consider a hyperbolic orbit to be a true orbit; beyond the Local Group, galaxies are not gravitationally bound. - Running On Brains (talk) 15:40, 18 July 2012 (UTC)


 * The three body problem is notoriously complicated. To give a simple example, suppose Pluto had the Earth's Moon revolving around it in the opposite direction, and one of those little satellites tried to sneak past five meters from its surface.  Would the rock still be orbiting the barycenter?  Nope - it'd go ass over teakettle in some odd direction and probably never be heard from again.  It can't be modelled simply, except in roughest approximation. Wnt (talk) 17:25, 18 July 2012 (UTC)


 * Note that Pluto and Charon don't have any close-in satellites orbiting the pair. I suspect this is because any such orbit would be unstable, again with the possible exception of an orbit at a Lagrange point. StuRat (talk) 20:47, 18 July 2012 (UTC)
 * The Pluto-Charon system doesn't have any stable Lagrange points. L1, L2 and L3 are always unstable and L4 and L5 are stable only when one object is more than about 25 times the mass of the other (see Lagrangian point). Pluto is only about 9 times the mass of Charon, so L4 and L5 aren't stable. (There might be some quasi-periodic orbits, but they would only be stable in the short-term.) --Tango (talk) 02:20, 19 July 2012 (UTC)

Creationist time line refuted by Neandertal DNA
Scientists figure that the last Neanderthals were about 26000 years ago. Creationists reckon that must have been less than 6000 because the world was created on 4004 BC. And they argue that the presence of Junk DNA in the human chromosome is the result of man's degeneracy over the interim time, as his sinful nature corrupts what was originally a perfect system in the Garden of Eden.

But they DO agree that there are no Neanderthals now, and that they must have died out thousands of years ago. I would thus argue that in that scenario, the DNA of preserved human bodies thousands of years old, Neanderthal or some other variant, should then show much less "corruption" by embedded viruses and so on. If the world is only 6000 years old, and our current DNA has been progressively corrupted over that time, then DNA from even two thousand years ago should show a much smaller degree of such corruption.

But I gather they don't. I am interested to see if there is any difference at all in such junk DNA effects between us and them, and if that difference can lead to a callibration of how different they were to us, and how long ago they died out. Myles325a (talk) 07:42, 18 July 2012 (UTC)


 * Yes. Please see 75.166.200.250 (talk) 07:47, 18 July 2012 (UTC)


 * But radiocarbon dating seems like a much easier and more accurate way to accurately date those fossils. Of course, creationists will ignore that, but they can also ignore DNA evidence and all of geology, astrophysics, and every other branch of science that disproves their world view. StuRat (talk) 07:54, 18 July 2012 (UTC)


 * It's a simplification to say that all creationists, or even all young-earth creationists, believe the world began in 4004 BC. That's just the Ussher chronology. But StuRat is right: some beliefs can be reinforced by science (such as the intuition that humans and apes have something in common), some are intrinsically unprovable (such as Deism's model of God - which can arguably ignored as irrelevant, but not specifically disproved), and some (like Creationism) are held by their believers directly in the teeth of overwhelming scientific evidence to the contrary. Something as sophisticated as junk DNA analysis isn't on the radar for these people, because they treat rigorous scientific methods as intrinsically suspect. AlexTiefling (talk) 08:07, 18 July 2012 (UTC)


 * The creationists are not very good at expressing themselves, so they get too little credit. Their typical retort to such things is to say "Were you there?".  When we apply the tools of natural science, we assume that the consistent timeline we see in our experiments, which seems consistent with our own, is the only timeline.  That if we go back generation after generation, the clock on the wall matches the time people experienced, and the circumstances we live under are those which our examination of historical sites supports.  It is, however, definitely true that human experience can misperceive the world, that the timeline as we recall it is not what the facts indicate.  Can we rule out, with certainty, that over time there is not some systematic bias - that indeed, our past, as sentient consciousness, is in what we could call one parallel universe, and our future in another?  Creationism involves a very deep rejection of the materialistic certainties (faith?) of the secular perspective, and it may not be one that is satisfactorily redressed merely by more facts showing the consistency of the natural science timeline.  We can argue to the consistency, clear immediate usefulness, and tremendous beauty of the natural science perspective; but to argue that our perception of the world is truly, absolutely real and not at all a matter of imagination or misperception?  That is beyond our kingdom. Wnt (talk) 12:22, 18 July 2012 (UTC)


 * Wnt's words seem to be a long way of stating that the rate of time could have changed without our knowing it because we don't know everything and cannot be certain there isn't some aspect of physics that we've missed or not yet discovered. As such, it is true in logic, but does not seem very likely, given the weight of evidence in all manner of science fields of study, from geology, study of dinosaurs, radio isotope dating, you name it.  I have actually had Christian creationists and Islamic people state this same argument to me.  Wickwack124.178.177.30 (talk) 13:30, 18 July 2012 (UTC)
 * Actually, that's not what I meant. What I mean is more that you could be sitting there, typing away at the computer, and the next moment you look up and out at an audience around some futuristic zoo enclosure neatly labelled: "Day In the Life of an Earthling: Reconstructing the Century of the Anthropocene Extinction".  Or many, many other things, some, one can hope, guided by a perfect hand, and possessing a greater level of reality. Wnt (talk) 16:34, 18 July 2012 (UTC)
 * The logical argument that we cannot know that the world/universe, etc, is real orginated with ancient Greek philosophers, but is it anything more than a perceptive exercise in logic? Wickwack124.178.177.30 (talk) 13:30, 18 July 2012 (UTC)


 * Although I think creationists are foolish in being such, I don't see that neandertals having a goodly amount of junk DNA proves anything. A Creationist might argue that they were an abombination, extremely degenerate.  Further, evidence is coming to light that so called junk DNA is not so much junk after all - recent issues of the magazine Scientific American have elucidated research into this aspect.  Wickwack124.178.177.30 (talk) 13:39, 18 July 2012 (UTC)


 * Even with such evidence, I doubt it will change anything. When faced with the harsh reality that the natural world does not resemble the world described in the Bible, literal creationists will always rather assert that the world is wrong because the Bible is always right. They can not see what is because they're too caught up with what should be. Good luck with making them see that.-- O BSIDIAN  †  S OUL  17:40, 18 July 2012 (UTC)


 * Another line I've heard from creationists is that their god deliberately made the world with evidence that seemingly contradicts the Bible simply to test their faith. Once they take that position, no evidence will prove anything to them. HiLo48 (talk) 19:48, 18 July 2012 (UTC)


 * I want everyone to memorize this aphorism. Right now.  Commit this to memory: "You cannot reason someone out of a position they did not arrive at via reason."  Learn it.  Know it.  Live it.  It doesn't matter what evidence you present to the YEC crowd: They evaluate the evidence through the filter of their predetermined conclusion, so there's no sense in trying to talk them out of it.  Its a lost cause.  -- Jayron  32  20:07, 18 July 2012 (UTC)
 * I wonder why you think it's not worth the effort to try. 75.166.200.250 (talk) 22:50, 18 July 2012 (UTC)
 * Because the evidence is hardly hidden or arcane. If reality punched you in the face every day, and you refused to acknowledge it, what good is one more punch... -- Jayron  32  23:24, 18 July 2012 (UTC)
 * From their perspective, it is more hidden and arcane than scripture, because of peer pressure, the promise of life after death for believers, and similar. 75.166.200.250 (talk) 20:40, 19 July 2012 (UTC)

airlifting a diver to hospital
So i was in vanuatu scuba diving the other day, a group of islands only one of which has a hyperbaric chamber to treat sombody with the bends. How might a diver with the bends be moved with haste to the chamber, is airlifting possible since increased altitude would worsen his problem. Can the cabin pressure of conventional planes be maintained at 1 atmosphere, or perhaps airlift by helicopter where the helicopter stays close to sea level? 110.175.191.101 (talk) 12:37, 18 July 2012 (UTC)


 * For airframe cost reasons, aircraft are presurised to the equivalent of 2000 m (or a little above for older aircraft), ie 80% of sea level pressure (ref http://en.wikipedia.org/wiki/Cabin_pressurization#cite_note-1), this is beacuse it is a good safety margin below the altitude (~2500 - 3000 m) where some pasengers may experience discomfort with certain medical conditions. A helicopter is not necessary for low level flight - all types of powered aircraft are required to be above the same minimum height when not actually landing or taking off - typically 1000 feet, and may be higher in built-up areas.  Perhaps pilots undergoing rescue can get authorisation to fly lower, but 1000 Ft /300 m altitude has 95% of sea level pressure and should have negligible additional medical risk. Airfarme structural safety means you will not find an aircraft that can maintain sea level presure.  Wickwack124.178.177.30 (talk) 13:15, 18 July 2012 (UTC)


 * It's more like 98% at 1000 feet. And try flying at 1000 feet in Dubai. Or Shanghai or Manhattan. There's at least 18 things at 1000 feet to fly into in Dubai. Sagittarian Milky Way (talk) 21:47, 18 July 2012 (UTC)


 * If pressure is an issue for transporting ill passengers, it would be easier to transport a hyperbaric chamber. Ochson (talk) 14:39, 18 July 2012 (UTC)


 * "Helicopter transport necessitates the pilot maintaining altitude at < 500 feet. Fixed-wing transport should be limited to aircraft that can maintain cabin pressure at surface 1 atm (e.g., Lear Jet,...". -- Finlay McWalterჷTalk 15:14, 18 July 2012 (UTC)


 * I believe that the helicopters typically used to transport people to a hospital aren't normally pressurized at all. Thus, they can't fly very high.  However, I seem to recall hearing about one rigged for mountain rescue, where low air pressure might cause the pilots to pass out, having a pressurized compartment for the crew, and 2 separate rescue nacelles which were independently pressurized, so the patient(s) in them can be slowly returned to sea level pressure.  I'd think the same strategy could work, in reverse, for divers.  However, this is likely to be cost prohibitive except in areas with lots of divers.  Also, one disadvantage to this system is that medical personnel can't tend to the patient during the flight, but, if they are likely to die without it, it's worth that risk. StuRat (talk) 20:22, 18 July 2012 (UTC)


 * I grew up a short distance from Whipps Cross Hospital in London, which at the time had one of only two hyperbaric chambers in the country. There were fairly regular visits from RAF and RN air-sea rescue helicopters carrying customers for it. I'm fairly sure the Westland Whirlwind didn't have a pressurised cabin. Alansplodge (talk) 22:21, 18 July 2012 (UTC)

Circles, flares around sun in photography.
I'm not sure this is the right section for asking about it

In photography sometimes when the sun is around the corner, strange circles appear in the photography. Something like this you can see the bright behind the tree.

What are those? How are they generated?, (How can I shoot those?) 65.49.68.173 (talk) 14:43, 18 July 2012 (UTC)


 * Those are lens flares, caused by internal reflections within the camera lens. You can photograph them by taking pictures with very bright objects in or near the frame.  That process is easier if you a camera where you look through the lens (such as an SLR camera or, I suppose, any digital camera with a viewscreen on the back) rather than through an independent viewfinder.   Various lens filters can further enhance the effect. &mdash; Lomn 14:51, 18 July 2012 (UTC)


 * I'm not 100% sure, but perhaps Bokeh is related to this. Bus stop (talk) 14:59, 18 July 2012 (UTC)


 * Bokeh is not related to this. Lens flares are internal reflections of light which cause light to appear in front of foreground objects, bokeh is just differences in focal length; foreground objects will not be impacted. - Running On Brains (talk) 15:34, 18 July 2012 (UTC)

Camera on a timer in 1850?
I'm writing an article on Johann Coaz and am a little suspicious of a photo I've put in the article. This photo (right) purports to show Coaz and two others on the first ascent of Piz Bernina (according to its description in the Commons). Given that there was no one else around, could this photo have been taken on a timer with the technology available at the time (I'm hoping it could have been), or is it a shot from a different ascent that has been mislabelled? The rockiness of the summit could certainly be Piz Bernina. The source (naturfreunde-maiengruen.ch) is not very helpful at all... Ericoides (talk) 16:02, 18 July 2012 (UTC)
 * Here's a little history of the camera shutter for some background. This suggests that in 1850 the photographer would not have been using a shutter as we would recognise it, so also wouldn't be able to use a release timer. It seems that they would have come in about 1880. Having said that, I think that if the camera did have a shutter, the technology existed (Clockwork) to enable a delayed shutter release. However, looking at camera technology, this page tells us that Wet plate photography didn't come in until 1851. This photo (if it was taken in 1850) must, therefore, be a Daguerreotype. Here you can see the process involved in taking such a photo, with exposure times from 10 seconds to 30 minutes(!). A reasonably long exposure (maybe over 30 seconds or so) might be enough for the photographer to quickly skip round in front of the camera and arrange himself in an 'I've been here all along' pose. What do you think? - Cucumber Mike (talk) 16:15, 18 July 2012 (UTC)
 * An ingenious reply, thanks, but would there not be a trace of his movement on the image? Ericoides (talk) 16:31, 18 July 2012 (UTC)
 * At low sensibility film, there wouldn't be any traces. The sensitive material just register up a certain threshold. If the exposure time is several minutes, then things in the ball park of some seconds won't show up. Apparently, it was not unusual for photographers in the XIX century to portrait themselves: []. OsmanRF34 (talk) 16:36, 18 July 2012 (UTC)
 * OK, that sounds sensible, thanks. Two further questions: which one is Coaz, and which one took the photo? My hunch is that Coaz is on the right, looking at the camera, and the fleet-footed photographer is the man standing on the left (who might well also be Coaz). Ericoides (talk) 17:19, 18 July 2012 (UTC)
 * Looking more closely at the photo, the standing man and the man sitting on our left are holding things that look a little like posing stands. Could it be, therefore, that the man sitting on the right looking directly at the camera is the photographer? Also, you labelled the photo 'Coaz and the Tscharner brothers'; the two men who look most like brothers are the one standing and the one on the right (the potential photographer) - they seem to have similar facial features. If I've got that right, my bet for Coaz would be the man sitting on the left. Admittedly, I'm getting into rather serious guessing now! - Cucumber Mike (talk) 21:37, 18 July 2012 (UTC)
 * They are holding alpenstocks, the rather long version of the modern ice axe. Ericoides (talk) 05:51, 19 July 2012 (UTC)

Also we seem to be looking down on the summit. When was the helicopter invented? ;-) Alansplodge (talk) 22:16, 18 July 2012 (UTC)
 * It's an optical illusion. The camera is probably on a standard 5-foot-tall tripod, sitting on a nearly-level ridgeline, aimed slightly downward. --Carnildo (talk) 22:47, 18 July 2012 (UTC)
 * I have taken pinhole camera photos of myself and others, with exposures of over a minute, and it was quite possible to start the exposure, run to my place in the photo, then run back and stop the exposure. I would not care to run across the ice and rocks evident in the photo. How sure are you there was no 4th person present? If I carried a view camera on a tripod up a mountain, I would not think it much of an additional burden to also bring a remotely operated shutter, even though in those days exposure control was usually by removing the lenscap, counting or timing the exposure with a watch, then replacing the lenscap. A "Bulb" shutter exposure was done by squeezing a rubber bulb attached to a long, thin rubber hose, with a shutter which opened when the bulb was squeezed and closed when it was released. Such bulb-hose-shutter arrangements were in use by 1853: "The Photographic journal: Volume 83, books.google.com Royal Photographic Society of Great Britain, Photographic Society of London - 1853 - Snippet view: "The camera ran on castors, and its height was adjusted by attachment to a pair of tall steel rods, up and down which it slid, and could be fixed at any desired position. Fxposure was made by means of a rubber tube and bulb. The shutter ..."

The adding of a remotely operated shutter would have been a pretty obvious alternative to running back and forth on a slippery mountaintop. The photo as presented is too low res to look for evidence of a remote operated shutter. Photos by 1850 were made on paper negatives, and not just Daguerrotypes. Edison (talk) 19:51, 19 July 2012 (UTC)
 * I think we can be certain that if this is a photo of 13 September 1850 then no one else was present. All records of Piz Bernina's first ascent say it was by Coaz and the two Tscharner brothers. On such a prestigious first ascent we'd definitely know if there was a fourth person in the party. Ericoides (talk) 07:37, 20 July 2012 (UTC)


 * I think that the strange quality of the light on the rocks and the completely indistinct background of the sky point toward a very long exposure. Wnt (talk) 11:08, 20 July 2012 (UTC)

Noise reduction
Given a mainstream PC (with a mainstream microphone and mainstream loud speakers/headphones), can a program running on it actively cancel noise? I don't mean any noise reduction filter, that can be applied on a file on the computer, just reducing the environmental noise for the user. OsmanRF34 (talk) 17:48, 18 July 2012 (UTC)


 * Yes. Start by reading Noise-cancelling headphones. You can get them for a few quid on Amazon these days but the bottom line depends a bit on how white the noise is--BozMo talk 17:53, 18 July 2012 (UTC)


 * Read carefully: I said with mainstream headphones, not with noise-cancelling headphones. I want to know if a PC (with a mainstream microphone and mainstream loud speakers/headphones) can cancel noise, not if there are noise cancelling headphones at Amazon for a few quid. OsmanRF34 (talk) 18:06, 18 July 2012 (UTC)


 * Ok/ What software are you proposing to use? It is technically okay if you fix the distance between the microphone and headphones and resign yourself to it only working for wavelengths a lot longer than that (so say two octaves below middle C) but it would be a real faf to program versus the buy a cheap set of phones with a microphone inbuilt which does it better. I think the answer is probably "not with mainstream software". --BozMo talk 18:40, 18 July 2012 (UTC)


 * Wouldn't latency be a problem (amongst other things)? Even with ASIO, I'm just not sure PCs can achieve the latencies required for such purposes compared to dedicated hardware although I guess with highly predictable noise it may still work slightly. Note that both our article and mention it only really works for low frequencies and placement of the mics are important. Nil Einne (talk) 19:08, 18 July 2012 (UTC)


 * This depends on the characteristics of the noise and the signal channel. If you are talking about reducing non-speech noise, try running the signal through a vocodec like Speex and see if that makes it more ineligible. If you can characterize the noise spectrally and the channel in more detail, then I can give you a better answer. 75.166.200.250 (talk) 20:22, 18 July 2012 (UTC)


 * I used to work on Lotus' ANC system for cars. At the time, late 80s, PCs were 286s and the like, and could not process in real time. For real time 6x4 cancellation we used a TMS chip, and could cancel up to about 200 Hz. The chances are you need a higher frequency limit than that but only a single channel system, with the same cancellation signal to each ear. As such I think that current PC probably has the grunt, but getting timely access to the audio circuitry might be tricky in a multitasking environment. If this is a research project, go for it, but my noise cancelling headphones cost about an hours pay, and they are GREAT. Greglocock (talk) 08:47, 19 July 2012 (UTC)


 * It's a DIY project. So far, maybe it needs a dedicated chip, to deal with the problems cited above, something like an arduino chip. OsmanRF34 (talk) 16:22, 19 July 2012 (UTC)
 * If there's an Arduino which can do audio DSP, I don't know about it. Think Raspberry Pi. 75.166.200.250 (talk) 06:44, 20 July 2012 (UTC)

Meowing bird sound in western Montana
In western Montana while camping next to the Clark Fork River I heard a bird that made a MRRREEEOOOW MRRREEEOOOW MRRREEEOOOW type sound. Any idea what it was? (It was not a cat. I know this.) Whoop whoop pull up Bitching Betty 17:54, 18 July 2012 (UTC)
 * A Google search for "meowing bird sound" leads immediately to the Gray Catbird. Our article contains a sound sample; you can see if it sounds like what you heard. Looie496 (talk) 18:06, 18 July 2012 (UTC)
 * ...although a mockingbird can also do that. Looie496 (talk) 18:11, 18 July 2012 (UTC)
 * They're also in YouTube and quite remarkably cat-like (see, , ). It could also be the related Mockingbirds and other mimids (see ).-- O BSIDIAN  †  S OUL  18:17, 18 July 2012 (UTC)

That's pretty obviously not it. Whoop whoop pull up Bitching Betty 00:03, 19 July 2012 (UTC)


 * Obviously. Details, man! How'd you know it was a bird? Did you see it? Was the sound angry-cat-like, angry-Ferrari-like, angry-boy-pretending-to-be-an-airplane-like? Fast? Loud? Soft? Repeated how many times? It could be anything from Yellow-headed Blackbirds (sounds like rusty hinges interspersed with plaintive nggrrraooows), any birds-of-prey (which though distinctive, can sound like an angry cat at lower pitches), other mimics like magpies (which like mockingbirds and catbirds can sound like anything they want to sound like), or even squirrels (which do meow like cats apparently, here's an angrier mrrao-ing one).-- O BSIDIAN  †  S OUL  04:25, 19 July 2012 (UTC)

Radio comedy live audience
I was in the audience of the recording of a BBC radio comedy the other day. Musing about it since I was wondering whether the left channel of audience noise was the audience's left or stage left (actor's left, audience's right)? 10.64.0.169 (talk) 18:55, 18 July 2012 (UTC)


 * Call the show's producer's office and ask for the sound stage technician. It might not be something they try to keep constant all the time. 75.166.200.250 (talk) 20:24, 18 July 2012 (UTC)


 * Ideally, since when you view it at home, you "become" the audience, then they should have the left channel be audience left. That way, if an actor looked to the left (or on radio, said "Hey, you on the left in the funny hat...") and asked somebody on the left side of the audience a question, the answer would seem to come from the correct place.  However, in shows where there's no interaction with the audience, it wouldn't much matter. StuRat (talk) 20:39, 18 July 2012 (UTC)
 * The host often introduces people saying where they are seated ("On my left, we have XYZ, and on my right, we have ABC."). I would expect the stereo to be set up in such a way as those directions make sense (with the listener in the audience's position, I agree). --Tango (talk) 03:48, 19 July 2012 (UTC)

London Weather
My friend said she heard on the radio that the UK was doing something to the atmosphere, like sending dry ice up on weather balloons, to force the jet stream to move so there would be "good" weather for the London Olympics. Is this true? 5.48.60.180 (talk) 23:07, 18 July 2012 (UTC)


 * Dry ice wouldn't move the jet stream, but, what it could do is seed clouds to make it rain. Obviously they don't want rain at the Olympics, therefore they would do this some distance away, so that clouds headed for the Olympic venues would be all "rained out" by the time they arrived. StuRat (talk) 23:10, 18 July 2012 (UTC)
 * Correct. Please see Weather modification. 75.166.200.250 (talk) 23:17, 18 July 2012 (UTC)


 * Is "the UK was doing something to the atmosphere, like sending dry ice up on weather balloons, to force the jet stream to move"? No. As for the link to our weather modification article, the section in question relates to attempts to weaken tropical cyclones - and we don't get many of them in London. AndyTheGrump (talk) 23:21, 18 July 2012 (UTC)
 * Right. Also, I suspect that these might be military secrets. 75.166.200.250 (talk) 00:14, 19 July 2012 (UTC)
 * Note that as our article and the source it links to mentions, China claimed to be doing that during the last Olympics. However they have extensive involvement in the field of weather modification, including a Beijing Weather Modification Office and according to various sources something like '$100 million a year and employs 50,000 for rainmaking; 6,781 artillery guns and 4,110 rocket launchers; 30 aircraft'. While they normally try Cloud seeding to encourage rain over areas of drought etc, the method they tried to use during the olympics was fairly similar but as StuRat suggested the attempt was to get it to rain in areas away from the olympics . Our cloud seeding article and the earlier linked source also suggests they tried or were going to try to get it to rain before the olympics to help clear pollution.
 * As our article implies, whether their effors actually did anything useful is in much debate, as I understand it the field of weather modification is a controversial one with limited science backing up the claims of success (given our current limited ability to predict the weather, you can't know what would have happened if you didn't do anything so the only real way you can test your claims is by randomly choosing when to attempt modification and then carrying out statistical analysis to see if there's any evidence of a change but given how variable the weather is, you really need quite a long term project). Note that in one of the sources, even one of the key players from China said it wouldn't help much with big rain clouds, only small ones.
 * I somewhat doubt the UK will be attempting the same thing, not just because AFAIK they lack any real infrastructure (I mean they could easily adapt what they have but they'd still need to do more work then a country which already does it a lot), but as I understand it in most developed Western countries weather modification attempts are only generally done for research purposes (although not surprisingly I think a lot of research comes from China although some may question the quality of some of the journals it's published in which I believe includes ones from China) given the perceived lack of any scientific evidence of success (although our article suggests there may be some done for non research purposes in the US and Austria). As our article suggests weather modification attempts are also sometimes carried out in other parts of Asia where they either don't agree with the lack of evidence or don't care so much.
 * Nil Einne (talk) 05:00, 19 July 2012 (UTC)