Wikipedia:Reference desk/Archives/Science/2010 September 9

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

September 9

Laser beam expansion rates?

I've seen a few articles recently about laserstrikes on commercial aircraft coming in to land at various airports around the world, including a few discussing arrests of the perpetrators. The articles always mention how the laser fully illuminates the cockpit, and in one case the pilot was temporarily blinded and the co-pilot had to land the plane. That makes me wonder how wide the laser beam is at these altitudes. Considering it's only 1 or 2 mm wide at the point of emission, how wide would your average Class 2 laser be at 2000 feet? Or are these people using Class 3+ lasers to do their dirty work? Masked Booby (talk) 01:50, 9 September 2010 (UTC)

Do you have links to these articles? --Jayron32 01:56, 9 September 2010 (UTC)

This one was on BBC News some time back: Police fight back on laser threat. Nimur (talk) 01:58, 9 September 2010 (UTC)

There are many, if you had bothered to look, Jayron. Google News results Masked Booby (talk) 02:31, 9 September 2010 (UTC)

My 50 mW green laser pointer (very typical for the kind used in these laser attacks) has a beam that's 5 mm wide at 383 cm, so that's a beam angle of 0.0013 radians. At 1000 m, for example, it would be 1.3 m wide; at 2000 m, 2.6 m wide. --99.237.234.104 (talk) 03:10, 9 September 2010 (UTC)

Yes, but there will also be a loss of luminosity commensurate with the spreading of the beam. A beam that puts a dot of radius 1.3 meters will be (1.3/.005)² times less luminous, at those levels it may not even be noticed... --Jayron32 03:17, 9 September 2010 (UTC)

Slight correction: the laser beam is 2 mm at the origin, which makes the beam angle only 0.00078 radians. The beam would only be 0.8 m wide at 1000 m.

Pilots definitely do notice green lasers being shone at them at distances on the order of 1000 m. Pilots coming in for landing routinely suffer flash blindness from them, sometimes forcing the co-pilot to take over and land the plane. --99.237.234.104 (talk) 03:25, 9 September 2010 (UTC)

. Please cite sources; this is a Reference Desk. Comet Tuttle (talk) 17:09, 9 September 2010 (UTC)

Um, what I said about the pilots comes directly from the links that the OP gave. As for my own experiment, I admit that's OR. --99.237.234.104 (talk) 07:08, 10 September 2010 (UTC)

Hostage survival rates in modern times?

Here's an unusual question for you - has anyone ever studied/compiled statistics on the survival rates of hostages in modern times? By modern times I mean since the widespread prevalence of involuntary hostage-taking as opposed to the centuries old practice of exchanging people as collateral of sorts. Masked Booby (talk) 02:36, 9 September 2010 (UTC)

The FBI have apparently tried to do something with their HOBAS system but it only covers the US and Canada. See here for example. It gets a mention in FBI_Crisis_Negotiation_Unit#Initiatives. Sean.hoyland - talk 05:07, 9 September 2010 (UTC)

Stamp protection

The last time I bought pre-stamped envelopes from the post office (United States, btw), the stamps were actually pre-printed to the envelope. I took a good look at them, and there doesn't appear to be anything special about the stamps. They seem to be made of normal ink, and I can't see anything distinctive between them. Is there any kind of hidden protection on the envelopes or in the printed stamp to prevent someone from getting a high quality scan of the stamp and printing their own? Someguy1221 (talk) 09:50, 9 September 2010 (UTC)

In the UK stamps have, I understand, invisible phosphorous markings which allow their amounts to be automatically read. Your envelopes may have something similar. You would probably have to fake the envelope as well, which would cost more than the cost of the stamps. One of the stamps articles says that stamps often have hidden information coded into them, so there may be a secret code that signifies that design of envelope it should be with. On pragmatic grounds as well as ethical, do not do it as you will probably be found out. 92.15.3.53 (talk) 10:53, 9 September 2010 (UTC)

An interesting side note; a few years ago as an experiment I made a postage frank in mspaint (I don't have a scanner), printed it onto an envelope with a inkjet printer, and mailed it to myself. It arrived 82.44.55.25 (talk) 11:11, 9 September 2010 (UTC)

And technically, one could use a 50 year old stamp or older (with sufficient postage) and it would not have the same hidden markings, but would still be a valid stamp. Googlemeister (talk) 13:02, 9 September 2010 (UTC)

I wasn't aware of the word "franking" in that context. It's perhaps appropriate that the Canadian satirical magazine Frank got into a bit of trouble for publishing fake stamps with bizarre and/or humorous saying and pictures on them. Despite Canada Post claiming that they used state of the art scanning technology to prevent fraud of this kind, the writers found that virtually all their illicit mail was delivered, regardless of how obviously fake the stamps were. I get the impression that the amount of fraud taking place is so low that it would be more trouble than it's worth to crack down on it. Matt Deres (talk) 13:37, 9 September 2010 (UTC)

All US stamps have been tagged (read this article by someone from the American Philatelic Society) since the 1970s. As Googlemeister notes, it's possible to use older stamps; as a stamp collector buying from other collectors, I've often gotten envelopes franked with lots of older stamps from when first-class postage was a lot less than it is today. Nyttend (talk) 00:58, 10 September 2010 (UTC)

Over-efficiency as a cause of extinction

If evolution favors those species which are relatively best at adapting to their environment, can over-efficiency then be considered a cause of extinction? For example, if a predator evolves over time to succeed 100% of the time, and its prey does not recover, and the predator adapts no alternative prey, then the said predator goes extinct (for the purpose of this question at least). Now if a predator is successful only 5% of the time but thrives, then could it be said that efficiency is not a favored trait (unless it is relative to the evolution of its prey's efficiency of escaping), so a species that is "over"-efficient, or "uber-adaptable", may go extinct. I somewhere heard this could be applied to saber-toothed cats. Is this a valid concept and where can I find a good article on this? (using a dynamic IP; may change) 64.85.214.138 (talk) 10:07, 9 September 2010 (UTC)

Sounds akin to Malthusianism and the Malthusian catastrophe - albeit I get the impression he was more concerned about humans outgrowing the carrying capacity of the earth. --Tagishsimon (talk) 10:19, 9 September 2010 (UTC)

I was speaking more towards an already extinct species, one that did not employ agriculture or domestication of other animals. I don't mean this as an overpopulation/humans-are-bad question. Sorry for not clarifying. 64.85.214.138 (talk) 10:35, 9 September 2010 (UTC)

The model still applies. Malthus may have been concerned with humans, but (AFAIK) was one of the first to suggest that populations of any sort are limited by resources available to them. I'm sure your extinction concept is valid, though I cannot point you at examples. --Tagishsimon (talk) 10:38, 9 September 2010 (UTC)

The Lotka–Volterra equations describes what typically happens in predator-prey cycles. Occasionally there is a boom of prey, this is followed by a boom of predator. This causes a crash of prey, followed (inevitably) by a crash of predators. It only rarely drives one of the species to extinction. However, some prey have evolved solutions that have made their predators extinct; see the 13 year cicada for an example, although that idea might not be correct. CS Miller (talk) 12:03, 9 September 2010 (UTC)

I have heard of this, with snowshoe hares I think, but this type of boom-bust cycle has had time to evolve so that it settles at some kind of equilibrium, and then swings in favor of the other species, then temporary equilibrium, then swings in favor of the other other species, etc. In your cicada example, you refer to when prey out-evolve their predator, what I am referring to is when a predator out-evolves its prey -- when no equilibrium has time to evolve. It is just boom- but no -bust; it's boom-you're prey is extinct and then boom-you yourself are extinct. When prey win, adaptability pays off; when predators win, they have no food (unless they can create or grow their own -- I'm focusing only on predators that hunt or scavenge). (using a dynamic IP; may change) 64.85.220.14 (talk) 12:40, 9 September 2010 (UTC)

The Lotka-Volterra equations may be a bit of a red herring for the purposes of this questions. The solutions to those equations are not stable limit cycles, but neutrally stable. This means there is nothing internal to the model that prevents the kinds of extinctions that the OP suggests. As I see it, the problem that the OP describes is not extinction through `over efficiency', but extinction due to over-specialization. Basically, if a species' ability to grow/reproduce is tied too tightly to a single other species, then the extinction of one can cause the extinction of the other. This has probably happened many times through history. This does cause evolutionary pressure. For instance, many plant and animal pathogens have evolved NON-lethality, essentially to circumvent the problem the OP describes. I suspect very few predators are limited to EXACTLY one prey species, and many exhibit prey-switching behaviour based upon prey density. SemanticMantis (talk) 19:11, 9 September 2010 (UTC)

Oh, and the LV equations WILL produce the single boom, both bust when parameterized as the OP describes above. SemanticMantis (talk) 19:13, 9 September 2010 (UTC)

Headache + lack of exercise

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). --TenOfAllTrades(talk) 14:17, 9 September 2010 (UTC)

k1

are there any k1 kickboxing deaths?—Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 13:28, 9 September 2010 (UTC)

Try the Entertainment desk. Brammers (talk/c) 06:18, 10 September 2010 (UTC)

power

How does the teethbrush charger transfer power to the teethbrush, when both parts are plantic because they get wet? Plastic doesn't conduct electrity —Preceding unsigned comment added by Whovandr. (talk • contribs) 13:38, 9 September 2010 (UTC)

Electromagnetic induction --Tagishsimon (talk) 13:39, 9 September 2010 (UTC)

Inductive charging, specifically. -- Finlay McWalter ☻ Talk 13:40, 9 September 2010 (UTC)

Why can't we remove scars?

When I was seven I got a tiny burn to the side of my face.

It looks like tere is a layer of skin missing from the shape of the burn and its pretty much invisible.

If skin cells are constantly regenerating why do we have scars?

There is no scar tissue from the wound its just looks like a tiny portion/layer of skin is missing.

I know its not possible to remove a scar with any of the current methods available. but would it ever be possible to remove a scar/ what would have to be done scientifically to remove a scar? —Preceding unsigned comment added by 139.62.222.73 (talk) 13:53, 9 September 2010 (UTC)

With MatriStem Wound Powder, a lady grew back part of her pinky finger. source: http://www.cnn.com/2010/HEALTH/09/09/pinky.regeneration.surgery/ 20.137.18.50 (talk) 14:30, 9 September 2010 (UTC)

yea, I heard about that but that is a little off topic.

Anybody else got info? —Preceding unsigned comment added by 139.62.86.190 (talk) 09:11, 10 September 2010 (UTC)

We sort of answered this question already here. The problem with scars is that the collagen gets deposited in a linear fashion to bridge the defect and hold it together, instead of in a random "basketweave" fashion which is what happens during normal skin development. In order to "remove" the scar, we would have to have a way to re-organize the dermal collagen. From a technical standpoint, this would require either a cell-based therapy involving injection of cells programmed to degrade the scar and re-establish the connective tissue correctly (remotely possible with current tech), or perhaps more futuristic technology like nanorobots (i.e. Sci-Fi). --- Medical geneticist (talk) 16:44, 10 September 2010 (UTC)

Ceramic pastes with high R values

I have these little metal rings used for holding eggs in while you fry them to keep them from running all over the place. These metal rings have stainless steel loop handles that stick up which get so hot as to be untouchable with unprotected fingers. I want to coat the top part of those stainless steel loop handles with some kind of material that is very resistant to changing its temperature. What commercially available product would fit the bill here? Thanks. 20.137.18.50 (talk) 14:24, 9 September 2010 (UTC)

I am dubious that a suitable material exists that you could successfully apply non-industrially (I wouldn't recommend asbestos!), though I'm open to enlightenment. Have you considered the alternative of using an oven glove or a similar but makeshift device? 87.81.230.195 (talk) 17:03, 9 September 2010 (UTC)

Wood? 92.29.121.183 (talk) 19:00, 9 September 2010 (UTC)

First: are you cooking on a gas range with it turned up really high? I fry eggs in a hot pan but turn the gas back down low. Once the albumin has turned white round the edges it should be possible to take the ring off and finish cooking. The loops tend to remain coolish (although you may have different ones). Have you tried lifting them off with a Carving Fork? Or an inverted wire coat hanger? Back to your question about R values. Polytetrafluoroethylene has good heat resistance whilst reaming a good insulator. Likewise there is Silicone rubber. The boots of the Luna astronaut where soled with this stuff to avoid them getting toasted tootsies. A way of getting very small quantity would be to take a ring to an electrical wholesaler and ask to see some cable for connecting hot water immersion heaters or other high temperature cable. The cable outer sleeving may just be the right size to slip over the loop. What would Gordon Ramsay use? His teeth? --Aspro (talk) 19:03, 9 September 2010 (UTC)

Your best bet may not be insulation, but active cooling. Soldering a large number of copper fins to the handles, or making handle extensions from loosely-coiled thin steel wire, may let natural convection cool the handles (or extensions) to the point where you can safely touch them. --Carnildo (talk) 22:03, 10 September 2010 (UTC)

Scientists break the speed of light

Are there any comments about such rumors? I can see them coming up again.--Email4mobile (talk) 14:45, 9 September 2010 (UTC)

We have an article on faster-than-light phenomena, including quantum tunneling as cited in the first Google result I looked at. It appears that this specific phenomenon is the 50-year-old Hartman effect. — Lomn 15:08, 9 September 2010 (UTC)

How about the two German scientists' (Sorry may be the 2nd older result about NEC reasearch)?--Email4mobile (talk) 15:20, 9 September 2010 (UTC)

The Hartman effect linked above specifically names the German scientists in question. Note that the article is now 3 years old. — Lomn 15:50, 9 September 2010 (UTC)

Potassium iodate used in bread

I always see this chemical used in bread. What does it exactly do? The articles are not specific. Would potassium chlorate be a cheaper alternative? --Chemicalinterest (talk) 15:31, 9 September 2010 (UTC)

It's used to ensure that people get enough iodine in their diet for correct thyroid function. Potassium iodate is commonly added to table salt for the same reason. A little bit of excess dietary iodine does you no harm, but a deficiency causes goitre. So no, you couldn't use potassium chlorate as an alternative! Incidentally, they use the iodate rather than the iodide because the iodide will slowly oxidize to elemental iodine, which wouldn't look too pretty in your bread or your salt. Physchim62 (talk) 15:35, 9 September 2010 (UTC)

A relevant paper abstract is here. Potassium bromate used to be used instead, as a bread improver. Brammers (talk/c) 15:37, 9 September 2010 (UTC)

No, the reasons for adding the two salts are different. Potassium bromate used to be used as a flour improver (apparently it strengthens the dough that is formed), although this rare nowadays. The potassium iodate that is added to flour in some countries is at a much lower concentration (about 2 ppm seems a common level), probably too low to have a useful effect on the strength of the dough. Physchim62 (talk) 15:59, 9 September 2010 (UTC)

I live in the US, if that helps. --Chemicalinterest (talk) 16:04, 9 September 2010 (UTC)

I do not see anything about iodine-enriched bread. The KIO₃ articles says it is used as a maturing agent. --Chemicalinterest (talk) 16:43, 9 September 2010 (UTC)

KI is added to my salt. Not the oxidizing anion iodate. --Chemicalinterest (talk) 16:43, 9 September 2010 (UTC)

Some countries use iodate for iodizing salt [1]. As for iodized flour (which will make iodized bread), our article on iodine deficiency mentions it with a reference. Physchim62 (talk) 16:58, 9 September 2010 (UTC)

In NZ, iodised salt is used to make iodine fortified bread [2] [3] [4]. I know folic acid fortified flour is used for bread in some countries including Australia (as also mentioned in our article), in NZ the plan was to add it during baking to enable organic breads to be excluded (I believe) [5] but the plan was deferred by the new government. Nil Einne (talk) 18:03, 9 September 2010 (UTC)

postman opened my door?

Question and responses removed. Questions that contain the phrase "Can I sue them" are requests for legal advice and should not be answered. Seek a lawyer if you intend to sue anyone. --Jayron32 04:21, 10 September 2010 (UTC)

Giants

As we know, there are many myths related to the existance of giants. However, in reality, actual "giants" are rare and those who have existed (eg. Robert Wadlow) are not as tall as those of the myths. So, my question is: what are the factors that limit people from growing 10, 12 or 20 feet tall? Many animals are bred for specific characteristics (eg. the Clydesdale horse); giraffes are tall and elephants are huge; in the past, there were many varieties of megafauna. So why not humans? 142.46.225.77 (talk) 15:58, 9 September 2010 (UTC)

It depends on how widely you're willing to apply the term 'human.' See Gigantopithecus, for example. Restricting ourselves to H. sapiens and close relatives, it seems that the right circumstances happened not to arise favouring development in that direction, but in principle they might in the (far) future. However, the necessary evolutionary changes would not be insignificant: consider that, like Robert Wadlow whom you mentioned, many human giants suffer from foot/leg/back problems because current human anatomy is not 'designed' to support their weight (square-cube law and all that). 87.81.230.195 (talk) 16:54, 9 September 2010 (UTC)

Our article Human height ought to answer this question, but does not; it just says, frustratingly, that growth subsides at a certain age. Once we've had a great answer here, could a knowledgeable editor improve Human height by adding the answer? Comet Tuttle (talk) 16:57, 9 September 2010 (UTC)

The ref to Gigantopithecus reminded me of a curious idea relating to human's body size (and brain size). Terrence Deacon, in his book The Symbolic Species, proposes a theory about why human brains differ from other primates. The way human brains, and bodies, develop (in the womb and in early childhood) "can perhaps best be described as though a human child is growing a brain from a much larger primate species. The human pattern of brain growth is appropriate for a gigantic ape, while the pattern of body growth is appropriate for a large chimp." How large an ape? Something around the size of Gigantopithecus. He explores the idea that humans did not evolve larger brains so much as smaller bodies. Or put another way, evolved larger brains by slowing the development of body growth but not brain growth. A key point is that humans don't simply have "larger brains" than other primates. Each part of the brain differs in how much larger or smaller than they "should be" for a human sized ape. The prefrontal cortex is the most "enlarged" (over 200%) and the olfactory bulbs the most "reduced". There's more to it than just this, of course, but it struck me as a curious notion. Perhaps a link to human neoteny? Pfly (talk) 19:36, 9 September 2010 (UTC)

Hmm, similar to some of Elaine Morgan's stuff in The Descent of the Child. She adds that the apparently anomalous lifespan of humans, compared to other apes our size, is in line with the size of our brains. So, that would be another way that we are more 'large with small bodies' than 'small with large brains'. 86.164.78.91 (talk) 13:16, 10 September 2010 (UTC)

There is little doubt that humans could be bred to be much larger than we are. But it would take hundreds of years of selective breeding. Who would go to the trouble? Looie496 (talk) 22:51, 9 September 2010 (UTC)

This guy's parents? Googlemeister (talk) 14:24, 10 September 2010 (UTC)

87.81.230.195 (talk · contribs) made some very good points "changes would not be insignificant" and "current human anatomy" re carrying that amount of weight. For a human to be that tall they would have to be so many changes that they might no longer be 'human', as we recognise them. Note that Wadlow at least looked rather thin and still had great problems related to his height /weight combination.("he required leg braces to walk, and had little feeling in his legs and feet.") He was 'only' 8 ft 11.1 in (2.72 m) and and weighed 485 lb (220 kg) at his death at 22.

• Lets compare a 6 footer to a 12 footer, keeping all dimensions in proportion so that they remain human. Height x 2, breadth x 2, depth x 2, I believe that their weight would therefore be 2³ = 8 x. However, all else being equal, muscular strength is relative to Muscle cross-sectional area (see point 2), so their muscles if remaining proportional, would only be 2x2=4. Weight x 8 but strength x 2 means that they would be half as strong as a 'normal' sized person.

• The bottom surface of the feet would also be x 4, with 8 x weight so twice as much weight per surface area.(look at elephant feet, very broad/flat and the legs, relatively short and very thickened bones. Highly modified from their distant ancestors and they are a quadruped).

• The spines cross section would also only x4 be while carrying 8x as much weight.

• Cooling might also be a problem, as the bodies volume has increased x8 but the Body surface area likely by a lesser amount. Not sure and I haven't calculated this. Elephants though tend to have large ears that are are also used as cooling devices.

♦ It seems our Giant human would live a (possibly) short life with constantly aching flat feet, if they could walk at all, scoliosis of the spine, and be very feeble. They could develop hugely thickened leg (and other) bones and huge feet. Or they would need to walk supporting the upper body on their knuckles (somewhat like Mountain gorillas) to spread the weight, becoming essentially a quadruped.

♦ There are probably other factors making giants unlikely that I have not covered, ie. blood pressure changes and food supply. If there are any flaws in my reasoning here, please point it out. 220.101 talk^\Contribs 05:31, 11 September 2010 (UTC)

Anatomy of a brain

Are human brains wired basically the same, the anatomy the same? Is it the chemicals and hormones that differ in each person, which control the strength of the signals among other things that make us unique? —Preceding unsigned comment added by 71.137.244.210 (talk) 16:09, 9 September 2010 (UTC)

To both of your questions, the answer is "yes and no." At the level of "gross anatomy" (what you can see by eye when you dissect a brain) the neuroanatomy is basically the same. Everyone generally has the same major structures, linked together by the same main bundles of axons. We also have generally the same wiring when you look at those structures under a microscope, for example the main cell layers of the cerebral cortex, the main cell layers cerebellar cortex, etc. However, it is safe to say that everyone has a unique microscopic arrangement at the level of the actual distribution of neurons in any given layer at any particular part of the brain, and a unique set of connections between neurons, etc. Secondly, in a general sense, we all have the same neurochemistry, meaning that our brains use the same neurotransmitters and neurotransmitter receptors to transmit signals between neurons. We share the same basic groups of neurons in various parts of the brain that use particular types of neurotransmitters. However, at a cellular level there will be all kinds of differences and fluctuations in terms of the strength of individual synapses. --- Medical geneticist (talk) 17:42, 9 September 2010 (UTC)

Right. There are hormonal factors that have important effects on personality, and probably anatomical differences that correlate with intelligence, but those things don't really make us unique. What makes us unique is memory, in combination with other effects of experience. Looie496 (talk) 22:48, 9 September 2010 (UTC)

What do you mean or if you could provide examples would be anatomical differences that correlate with intelligence? —Preceding unsigned comment added by 71.147.4.67 (talk) 03:19, 10 September 2010 (UTC)

See Neuroscience and intelligence. Lots of that stuff is pretty iffy in my opinion, though. Looie496 (talk) 06:13, 10 September 2010 (UTC)

Don't forget to read neuroplasticity, nature versus nurture and mental health. ~AH1^(TCU) 01:50, 12 September 2010 (UTC)

Integrated theory

The reason I've asked about breaking light speed rumors is that some are trying to reformulate physics and its laws reasoning that under the name of Integrated theory like this web under construction.

I will quote his introduction here:

"There is a need for a single unified theory, could explain all the phenomena of nature. and reduce all theories of physics in one, able to explain and interpret what interpreted by earlier theories and give more than all. predict conclusions of the future, of the realities of the universe. And interpretation of what all theories can not be interpreted or understood. Then put a convincing philosophical theory, based on scientific facts that are not in doubt, the aim to unification of the human thinking so not to be dispute. Uniting all forces of nature on the grounds that is properties of the material. And give causal explanation of all events and phenomena. And be simple and streamlined, universe simpler. And re-explanation of what other theories failed to interpret. This theory is different and collide with the old concepts, but not with the truth, a single, unified, comprehensive and integrated basis on truth. Most importantly, uniformity of laws, which apply to the solar system with atom Laws. it is causal theory of distinction. most of our concepts of physics, was based on erroneous grounds. such as Characteristics of the wave for the particles, and zero mass, and the idle talk about the fourth dimension, and the madness of Mathematics at super string theory, and leaps electrons Bohr, and the shortsightedness of the Big Bang theory. Theory relies new foundations and the most important is the new atomic model, adds particles to atom, smaller than electrons. and focuses on the structure of elementary particles. We got to know that this theory interpret black holes, dark matter, and sunspots. In short, tell us the truth about the universe. Relates to the impact of global warming of Earth's surface. Focus on the gravity, and develop a new understanding of energy. And provide a deeper understanding of the so-called forces of nature, and give a causal definition of the charge, and then address the speed of light, it have the ability to give causal answers to, all phenomena of nature. At first it seems weird and difficult to understand, because they contradict with the foundations of earlier theories, but after you complete the understanding it will be simple and very easy, and not to forget, and internally consistent, and enable us to conclude everything easily.", Dr: Sadi Said Mona

Do you think this mas is serious?--Email4mobile (talk) 17:03, 9 September 2010 (UTC)

Serious? Sure. Correct? Unlikely. See Fringe science and Pseudoscience. People claiming to have re-invented large segments of the study of physics are pretty common on the Internet, and Wikipedia's WP:V verifiability policy came into being largely to stop physics cranks from posting their fringe theories as articles here. Comet Tuttle (talk) 17:13, 9 September 2010 (UTC)

It's important not to conflate fringe with crank. The high-risk-high-reward area of any discipline is always on the fringe. Unfortunately the well-intentioned practice of saying fringe when you really mean crank has tainted the former word, and we now probably need a new one. --Trovatore (talk) 21:15, 9 September 2010 (UTC)

You're right; I'll be more careful in the future. Comet Tuttle (talk) 19:11, 10 September 2010 (UTC)

Looks like the site is trying to introduce a new deterministic holistic hypothesis competing with the Grand Unified Theory and others. ~AH1^(TCU) 01:46, 12 September 2010 (UTC)

Feynman Famous?

Hello again, this is sort of a follow-up to a previous question I asked a few weeks ago about how to pronounce his name. After reading "Surely You're joking", I started on a collection of his letters, and was struck by a passage that said how Feynman was very famous with the general public, almost as much as Stephen Hawking or Albert Einstein. However, when I told a few people that I was reading the letters of Feynman, only two people from the twenty I asked knew who he was (one was my Physics teacher, who I don't think counts as the general public); yet I have no doubt they would all have know who Einstein or Hawking were.

Is Feynman simply much more famous in the US? (I live in the UK)--HarmoniousMembrane (talk) 17:25, 9 September 2010 (UTC)

I would say that Feynman (and also Hawking) have largely been known in the public for their efforts to popularize science. People who are effectively spokesmen for science tend to be known during their lifetimes, but the public forgets about them relatively quickly after they die. By contrast, Einstein is known to the public for his actual science (other examples might be Newton or Galileo). When the science itself becomes part of the public awareness, then the person behind it tends to have a much longer legacy. Of course Feynman also did top notch science, but that was never really why he was known to the general public. Dragons flight (talk) 18:05, 9 September 2010 (UTC)

If Feynman had had crazy hair and his work could be put in a nutshell as compactly as $E=mc^{2}$ his image and therefore identity might have also been conveyed to Joe Six-pack via cartoons and other cultural pellets consumed by the general public. 20.137.18.50 (talk) 18:10, 9 September 2010 (UTC)

Good point! Path integrals just don't have the same simplistic elegance. P. D. Cook ^{Talk to me!} 18:22, 9 September 2010 (UTC)

From the Rogers Commission Report article regarding Feynman's role in investigating the Space Shuttle Challenger disaster: "During a televised hearing, Feynman famously demonstrated how the O-rings became less resilient and subject to seal failures at ice-cold temperatures by immersing a sample of the material in a glass of ice water." That may have been the point at which he got the most attention from the general public. Wikiscient (talk) 19:02, 9 September 2010 (UTC)

Surely it's more impact than compact that gives $E=mc^{2}$ and its discoverer lasting fame. --Sean 22:52, 9 September 2010 (UTC)

It's definitely true that the association with nuclear weapons boosted that particular equation's notice in the public eye (graphically depicted in this Time magazine cover from 1946), but Einstein was actually already pretty famous before the atomic bomb, on account of the widely publicized and popularized success of theories after the Solar eclipse of May 29, 1919, and because of his very public activism during World War I and against the Nazis. He was already a public figure long before the bomb, but the bomb really capped it off. --Mr.98 (talk) 23:46, 9 September 2010 (UTC)

Nazis were World War II. SpinningSpark 01:14, 10 September 2010 (UTC)

The Nazis took over and did all sorts of nefarious things related to Einstein well before WWII. (Much less if we taken into account their pre-power hijinks as well.) See Deutsche Physik, among other things. Einstein was known for his anti-Nazi stance years before the war had started. --Mr.98 (talk) 01:23, 10 September 2010 (UTC)

And Einstein was active in the pacifism movement during WW1, even though Wikipedia's article about him doesn't seem to mention it. See Martin Gilbert's book on the war, for example. So "during WW1 and against the Nazis" was quite correct. --Anonymous, 03:51 UTC, September 10, 2010.

Oh, yes, I didn't realize that was the part under dispute. Einstein was very active during World War I as well, I guess I should clarify. He was one of the most prominent German scientists who was outspoken against German militarism (most of the others climbed on the Kaiser's bandwagon without hesitation). Wikipedia's Einstein article is presently a huge mess and seems to have been taken over by at least one POV-pusher, so I wouldn't put much faith in it myself, unfortunately! --Mr.98 (talk) 12:43, 10 September 2010 (UTC)

Einstein was a popular figure starting in 1919, amplified in the 1930s, sanctified in the 1940s, and at his death became the symbol of "science" around the world. Hawking on the other hand was mostly popularized through A Brief History of Time in the late 1980s, if I recall correctly. Hawking is culturally poignant not because of his scientific work, but because of his "brain in a ruined body" symbolism. I don't think he's quite on the same level as Einstein as a cultural icon, but the symbolism is pretty strong. I suspect that in the long run, he will be more of a Feynman-level of popular understanding — someone that smart, science-nerds know about, but not the general public (unlike Einstein). Incidentally, though, my wife had a shirt on the other day with Einstein's photo on it, and someone (who happens to be quite uneducated) asked her, earnestly, if it was George Washington. So I suppose we should not overestimate even his penetration into the mind of the common man! --Mr.98 (talk) 01:28, 10 September 2010 (UTC)

FWIW, I think Feynman wrote in that book that in WWII Americans knew Einstein as a mathematician; few people knew what physics is. Imagine Reason (talk) 21:50, 10 September 2010 (UTC)

Thanks for all the answers, guys. I can definately see what you're getting at, but I thought someone might find it useful that quite a few scientists still think he was a great man, as shown in the Guardian today: Attenborough and Dawkins Brian Cox and Hawking--HarmoniousMembrane (talk) 16:34, 11 September 2010 (UTC)

Sure, he's well known amongst scientists and people who read about science. No debate there. But I doubt he's well known outside that rather limited sphere. Whereas probably everyone knows Einstein's face and most people would know the robot Stephen Hawking voice. --Mr.98 (talk) 00:09, 12 September 2010 (UTC)

Lumen Loss

All other things being equal, what would be the approximate lumen loss of a 130v 150w halogen lamp operating from a 120v source compared to a 120v 150w halogen lamp operating from that same 120v source (nominally 2400 lumens). This (marketing?) technique is sometimes used to advertise a longer lifetime or enhanced ruggedness but of course at the expense of lumens. hydnjo (talk) 20:09, 9 September 2010 (UTC)

Wrong question: Marketing? The nominal voltage may be 120 but 50% of the consumers live close enough to the sub-transformer to be supplied with 120 plus volts. This would shorten the life of a 120 volt rated bulb filament dramatically. Hence the 130 rating. Make sense?! --Aspro (talk) 20:53, 9 September 2010 (UTC)

Also, The human eye is more sensitive to sorter wave lengths (ie. 550 nm). An over-run bulb will run hotter (but not more efficiently). It will appear brighter (more energy being converted into light) and in wave lengths the eye is more sensitive to ) but to quote Tyrell: 'The light that burns twice as bright burns half as long, and you have burned so very very brightly, Roy. Look at you. You're the prodigal son. You're quite a prize! [6] --Aspro (talk) 21:05, 9 September 2010 (UTC)

The two products are sold side by side from the same manufacturer. One (the 120v 150w rated} has no claim as to extended lifetime or increased ruggedness. Right next to it is the 130v 150w rated one with the claims mentioned. I'm pretty sure that the two lamps are intended to be sourced from the same 120v (nominal) supply, I'm trying to find out what the reduction in lumens would be if I opt for the 130v version (claimed lifetime of 4000 hours if operated at 120v) vs the 120v version (claimed lifetime of 2000 hours if operated at 120v). Does that clarify? hydnjo (talk) 21:14, 9 September 2010 (UTC)

There is about a 9% difference between 120 and 130 volts. If your board voltage is 130 v you should be asking yourself if you want to run up and down the steps changing blown bulbs or not. If your at, or below 120v, then it don't really mater and its academic. The human eye adapts and I don't think you will notice, so it's a pointless question asking about lumen. In photography I think it will be less than a third of a stop. For what earthy purpose prey, do you neeeed to be sooo precise? Get someone to meter your supply and tell you how many volts you're getting (important:switch some things on so you have some load -like a cooker). THAT voltage should indicate what bulbs you buy, rather than how many lumens you feeeel you need. If however you really mean lumens, then please repost on Reference desk/Trivia --Aspro (talk) 21:46, 9 September 2010 (UTC)

Just in case anyone gets confused over in the UK or Australia. There they have an asymmetrical nominal voltage declaration. Bulbs carry the 240 volt rating, which is correct for the average voltage delivered. This takes account of the higher voltages that occur nearer to the sub-station. The voltage supply is of much better quality and thus, two voltage options on bulbs are not required.--Aspro (talk) 21:50, 9 September 2010 (UTC)

This has gone way beyond my intended concern but here goes anyway. The security floodlights around my residence are doubly housed 150w halogen lit. My home is powered by a nominal 120v service. I need to replace one or two of the bulbs at this time. For reasons of aesthetics I don't wish to have one lamp significantly less bright than its 150 cm away neighboring lamp. I was hoping to get a response as to how much (qualitatively) brightness difference I might expect to perceive from opting for the 130v version as opposed to the nearby 120v version - that's all! This thread has gone way off track from my original question perhaps because of my in-artfull presentation but if you think you know what I'm asking please chime in. Thanks hydnjo (talk) 22:41, 9 September 2010 (UTC)

Power varies to the square of voltage. Assuming the load resistance does not change with the lower voltage (not an entirely accurate assumption - cooler running = lower resistance) and the efficiency is linear with power (also not entirely accurate) the radiant output will be (120/130)² = 85% of previous output. You will be 15%, or 360 lumens down. This book suggests that a more accurate formula is 3.38 rather than 2 as the exponent. Using that gives you a loss of 24% rather than 15% from the simplistic calculation. SpinningSpark 00:37, 10 September 2010 (UTC)

We have an article on this Lamp rerating. --Gr8xoz (talk) 00:50, 10 September 2010 (UTC)

• Thanks to both SpinningSpark and Gr8xoz, you both figured out exactly what I was asking and both of you provided excellent references. Looks like I should stick with the same 120v lamps that are all around the house as the luminosity difference with the 130v lamps would be quite noticeable and annoying and not worth the extra life expectancy. And Gr8xoz you've shown once again that WHAAOE! hydnjo (talk) 01:32, 10 September 2010 (UTC)

This analysis has been done in detail constantly by lighting engineers since about 1881, with tradeoffs between efficacy and lifetime carefully measured and analyzed. Edison (talk) 05:27, 10 September 2010 (UTC)

I'm sure that's true, but without providing any links or information that answer the question (as SpinningSpark and Gr8xoz did), you haven't really added anything to the answer. Did you mean to include a link? 86.164.78.91 (talk) 13:04, 10 September 2010 (UTC)

It is not a requirement to provide a link or reference with every posting. Sometimes a lifetime of study of a subject provides insights which may be helpful. One may have read something in a reference work which is miles away in a library and not easily citeable. An additional point is that empirical formulas derived for, say ordinary tungsten filaments in vacuum may not be accurate for a bulb filled with inert gases, or those for a bulb filled with inert gas may not be accurate for halogen, and formulas accurate for 240 volt filaments may not be accurate for 120 volt or lower rated filaments. These are not laws of physics like an ideal gas law or Ohm's law. Edison (talk) 15:16, 10 September 2010 (UTC)

• OK - resolved without the template. Additional thanks to Edison for his pragmatism and to 86.164.78.91 for their support after some of the earlier comments. Edison is right, this has lots of scientific study and empirical evidence available. The reason for there being two such similar products next to each other is that a compromise product (the 130v version operated at 120v) has been found to be marketable with the portable "rough duty" customers who are less concerned about the amount of light loss (20% - 30%) than the ability to withstand rough handling. The 120v version is the optimal choice for the average user with a fixed (non-bumpy) location and provides the appropriate balance of luminosity and life expectancy. hydnjo (talk) 21:03, 10 September 2010 (UTC)

Asbestos: regulation and risk to neighbours in the UK

Hello.

It seems that most asbestos legislation in the UK deals with occupational safety - the safety of workers and the responsibility of employers. Most of the science I can find deals with the same thing. I am interested in the risk to the general public - and nearby neighbours in particular - that may or may not be caused by work such as demolition.

So, my question to Wikipedians who wish to help me is:

What are the known risks to occupants of neighbouring buildings, of the demolition of nearby buildings which are known to contain asbestos? What precautions - in relation to those residents - are prudent? What precautions are required?

I've tried to research this myself, but all I can find are general medical and scientific studies of the dangers of asbestos, and laws and regulations relating to occupational safety and procedures. I have tried hard, but I cant find any information to help me answer my question.

Please note: I am definately not asking for legal or medical advice - I am purely looking for background information, as this seems like a hole in the regulatory system here in the UK.

I would be very grateful for any links that may be of interest.

Many thanks to anyone who wishes to answer.

Contactless (talk) —Preceding undated comment added 21:52, 9 September 2010 (UTC).

The general law in the area is section 3 of the Health and Safety at Work etc. Act 1974:

General duties of employers and self-employed to persons other than their employees.
3.—(1) It shall be the duty of every employer to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that persons not in his employment who may be affected thereby are not thereby exposed to risks to their health or safety.
(2) It shall be the duty of every self-employed person to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that he and other persons (not being his employees) who may be affected thereby are not thereby exposed to risks to their health or safety.
(3) In such cases as may be prescribed, it shall be the duty of every employer and every self-employed person, in the prescribed circumstances and in the prescribed manner, to give to persons (not being his employees) who may be affected by the way in which he conducts his undertaking the prescribed information about such aspects of the way in which he conducts his undertaking as might affect their health or safety.

Of particular relevance to demolitions is regulation 29 of the Construction (Design and Management) Regulations 2007:

Demolition or dismantling
29.—(1) The demolition or dismantling of a structure, or part of a structure, shall be planned and carried out in such a manner as to prevent danger or, where it is not practicable to prevent it, to reduce danger to as low a level as is reasonably practicable.
(2) The arrangements for carrying out such demolition or dismantling shall be recorded in writing before the demolition or dismantling work begins.

With regard to asbestos, the prudent approach is to remove as much of the asbestos as possible before demolition; otherwise, the whole demolition job would need licensing under the Control of Asbestos Regulations 2006. I don't know of any specific studies done on the risks to neighbours during demolition work. Court cases are only just getting round to dealing with the health damage to neighbours of asbestos processing plants: these people are at far more risk because the (potential) exposure is longer. Physchim62 (talk) 22:54, 9 September 2010 (UTC)

It depends on whether the demolition of the building containing asbestos is conducted according to regulations or not, and the size of the building/amount of asbestos. If the demolition abides by the regulations, airborne asbestos levels will be very low and I don't think health precautions are necessary for neighbors in standard cases. As mentioned above, larger projects might be different. If you're particularly worried and it's a windy day, then you could stay inside and keep doors and windows shut, or use a mask. If you want to see more information on the aforementioned regulations, check out this link. Regards, --—Cyclonenim | Chat  23:00, 9 September 2010 (UTC)

Thanks to both of you for putting the effort in to reply. I should probably have said that I had found the legislation Physchim62 kindly found, and the HSE link that Cyclonenim gave. Thanks for those though guys! But it does seem strange that, other than the very general duty of care to others contained in these regulations, there is little mention of risk to others such as neighbours. Dont you think?

The HSE has lots of information about worker's safety - respirator types, fibres per cc of air, decontamination procedures, licensing rules etc. - but none that I can find about precautions for the general public. It is strange to see, on a construction site, workers in full plastic hazard gear, with gas masks and disposable boots - even mobile decontamination shower units - while only feet away are members of the public watering their pot-plants in t-shirts! It just seems like a slight disconnect to me.

Anyway, thanks a lot for your help.

Regards Contactless (talk) 00:32, 10 September 2010 (UTC)

This is not legal or technical advice, just an observation. I once underwent "official" training in US asbestos removal procedures. The jist of it is that asbestos had to be removed only in an environment (plastic sheeting, negative air pressure via HEPA filters) where it was not dispersed in the environment. The problem area was enclosed with layers of plastic to constitute a sealed area. It was wet down and then scraped off the beams, pipes, boilers, ceilings, or whatever by workers with respirators and protective suits, and bagged for disposal. When they were done, and showered, the suits went into disposal bags and the inner plastic walls, floor and ceilings went into disposal bags. Then the air was monitored to make sure there were no fibers drifting around, before all the plastic was removed. Those regulations would not have permitted open air removal with the fibers drifting around the neighborhood. Just knocking down the building and letting the fibers drift around would not seem in accord with the US standards I was familiar with. Edison (talk) 05:22, 10 September 2010 (UTC)

Exactly the same (or a very similar) system is used in the UK, and licensed contractors go to great lengths to ensure that no asbestos fibres escape to the outside environment. You should be aware, however, that asbestos and other potentially carcinogenic particles exist (in a very small quantity) in normal atmosphere in the UK (and probably elsewhere). The risk from these (and from most demolition work) is so low that most of us don't bother to wear special masks when going about our everyday tasks. If you are really worried, perhaps you should ask to see certificates of asbestos removal which should have been obtained before demolition work stated. There are always some "cowboys" who ignore regulations. Dbfirs 13:03, 10 September 2010 (UTC)

Thanks a lot for helping me out - those are good, reassuring answers. I'm definately not one to make a fuss about health - I just wanted to make sure that the protection rightly afforded to workers (who are obvioulsy at much greater risk) was not to the exclusion of the general public, especially as this is a very high density residential neighbourhood.

The contractor is definately licensed for the task and reputable. I think I'll just write a quick letter to the council (who approved and gave notice of the demolition) and just ask them to confirm that reasonable measures have been taken to minimise any danger to residents.

Thanks again for your help.

Regards Contactless (talk) 23:00, 10 September 2010 (UTC)

Particle board

is it possible to make particle board with epoxy or yellow PVA glue or urethane glue instead of formaldehyde resin —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 22:54, 9 September 2010 (UTC)

I suppose it is possible to create your own particle board at home using your own matrix and binder system; any suitible binder should work. However, I imagine that quality control would be an issue. The stuff that's made in big factories tends to have better uniformity of properties and conforms to higher standards than something you whip together in your workshop with sawdust and glue. --Jayron32 05:45, 10 September 2010 (UTC)

The article Fiberboard, which covers the class of building materials that includes particle board, mentions some of the issues with formaldehyde-based resin systems, and mentions some alternatives which are in production. --Jayron32 05:48, 10 September 2010 (UTC)

How do frogs get into an isolated marsh?

This is a question that has intrigued me. I will give an example.

As I like to do, I explored a dry drainage ditch to its source beside a shopping mall. There was a small pool of water and mud. As I walked past, several small frogs jumped in. The nearest frogs were in a pond about 1/2 mile away.

So: How did the frogs get there? --Chemicalinterest (talk) 23:14, 9 September 2010 (UTC)

Although virtually all frogs have to breed in water, they frequently don't have to live in it, and many species spend much of the year out of it (though often sheltering in shaded and moist nooks and crannies, especially during daylight), during which they can disperse considerable distances in search of 'greener pastures.' The frogs you saw might easily have travelled more than half a mile to this intermittent pond (though it's not unlikely that some live closer than that without your realising). Alternatively, they may be a small population living permanently around the site, breeding when water is seasonably available and sheltering in the aforesaid nooks etc when not.

It used also to be said that frogspawn is dispersed by its sticking to wading birds' legs and being transported by them from one body of water to another, but I'm not sure how much of this was merely assumption rather than observationally confirmed. 87.81.230.195 (talk) 23:46, 9 September 2010 (UTC)

The area is developed, so it is easy to spot marshes. --Chemicalinterest (talk) 00:16, 10 September 2010 (UTC)

Are you certain that they were true frogs, not just tree frogs? Nyttend (talk) 00:54, 10 September 2010 (UTC)

Yes, they are true frogs. Bronze frogs, most likely. They are one of the most common frogs in my area. --Chemicalinterest (talk) 10:55, 10 September 2010 (UTC)

Also, don't forget that there would be a very large and complex subterraneal storm water drainage system that I imagine frogs would love to travel around in. Vespine (talk) 02:29, 10 September 2010 (UTC)

Frogs like light more than darkness. The storm drain is at the end of the stream. The frogs are at the beginnning of the stream. The spring at the beginning of the stream has dried up, although the water is still high. That is why there is still a puddle there. Frogs normally like mud, too. It gives them a better place to hide. Cement is hard to hide in. --Chemicalinterest (talk) 10:55, 10 September 2010 (UTC)

Frogs can wind up in odd places. I once found a somewhat dehydrated and emaciated but quite lively frog in a small recess in a television mast on top of a house. I cannot picture the frog climbing up the wall of the house, and my best guess is that he was grabbed by a bird and subsequently dropped while the bird was above the house or perched on the mast. So a frog in an "isolated" pool is not at all surprising. Edison (talk) 05:12, 10 September 2010 (UTC)

That is strange. It reminds me of something similar. Many times when it rains, we find earthworms on our porch. The porch is about 2 1/2 feet above the soil. --Chemicalinterest (talk) 10:58, 10 September 2010 (UTC)

See Raining_animals#Frogs_and_toads for referenced, documented cases of frogs raining from the sky. It is rare, but it apparently does happen. Checking earlier in the article, apparently waterspouts and tornados can carry water-borne creatures some distance, resulting in rains of fish and frogs and other oddities. --Jayron32 05:16, 10 September 2010 (UTC)

Here's one possible answer. As our frog article says: Some frogs inhabit arid areas such as deserts, where water may not be easily accessible, and rely on specific adaptations to survive. The Australian genus Cyclorana and the American genus Pternohyla will bury themselves underground, create a water-impervious cocoon and hibernate during dry periods. Once it rains, they emerge, find a temporary pond and breed. Looie496 (talk) 06:11, 10 September 2010 (UTC)

I live in the eastern US, if that helps any. --Chemicalinterest (talk) 10:58, 10 September 2010 (UTC)

I saw a bird carrying a frog once, and then it dropped it. The frog was unharmed and hopped away to safety. Maybe that's how they got there Quadrupedaldiprotodont (talk) 14:19, 10 September 2010 (UTC)

Here in Ireland I have seen Common Frogs in a wooded area near my house from time to time even though the nearest lake is about half a mile away. I see them very rarely but they travel this far away from water nonetheless.--92.251.241.196 (talk) 18:19, 10 September 2010 (UTC)

For true frogs in genus Rana, half a mile is not a big distance. While adult frogs normally stay in the same pond, juveniles disperse to large distances in search of new ponds. This paper gives the dispersal distance of about 1000 m (0.62 mile) for the wood frog Rana sylvatica; but of course the dispersal distance depends on weather, terrain, and the species of frog. Half a mile is not a problem. In fact, many species of frog breed more successfully in vernal pools and other ephemeral bodies of water, as the absence of large fish guarantees reduced predation and reduced competition. It is probably also an evolutionary adaptation for the species to be able to spread to the new available habitats. --Dr Dima (talk) 18:21, 10 September 2010 (UTC)

They were young frogs, I could tell by the splash instead of the plunk. . --Chemicalinterest (talk) 20:09, 10 September 2010 (UTC)

I have seen young frogs jumping out of a muddy puddle in the middle of a trail in a forested region. The puddle was likely fed by a stream or even by intermittent rains. Could your frogs be breeding there whenever the puddle exists and has not dried up completely? ~AH1^(TCU) 01:25, 12 September 2010 (UTC)