Wikipedia:Reference desk/Archives/Science/2012 October 27

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.

October 27

Survive on alcohol

Can you survive longer if you have nothing else to drink except alcohol? Comploose (talk) 11:58, 27 October 2012 (UTC)

Survive longer than what? What kind of alcohol? It's possible that, say, in the absence of a water source, you would survive much longer drinking beer than drinking nothing, for example (beer is a source of water and calories and is not as dehydrating as most people believe). But if you're asking whether substituting all of your water with ethanol is going to make you live longer, the contrary is certainly the case. --Mr.98 (talk) 12:34, 27 October 2012 (UTC)

Penny, behind the bar: "What can I get ya?"

Sheldon: "Alcohol."

Penny: "Can you be more ... specific?"

Sheldon: :"Ethyl alcohol."

--Trovatore (talk) 23:00, 27 October 2012 (UTC)

A very logical answer, considering how much less desirable methyl alcohol is as a beverage. :-) StuRat (talk) 23:15, 27 October 2012 (UTC)

Yes, if you have just alcoholic beverages (vodka, wine, whiskey) at hand, would you survive longer drinking some of it or not drinking anything.Comploose (talk) 12:49, 27 October 2012 (UTC)

I think there must bee some limit between bear and 100 % alcohol above wich it is beter to drink nothing, but i do not know what that limit is.Gr8xoz (talk) 13:04, 27 October 2012 (UTC)

Before sanitation, people drank beer in Northern Europe and diluted wine in Southern Europe instead of water, which carried diseases. You can survive on those as your beverage indefinitely. Anything much stronger than beer will dehydrate you. μηδείς (talk) 19:41, 27 October 2012 (UTC)

Although (in England) they often used to drink small beer which had a very low alcohol content. "Some workers (including sailors) who engaged in heavy physical labour drank more than 10 Imperial pints (5.7 litres) of small beer during a workday to maintain their hydration level. This was usually provided free as part of their working conditions, it being recognised that maintaining hydration was essential for optimal performance."Alansplodge (talk) 18:00, 29 October 2012 (UTC)

This is often said, but the supposed mechanism is that it makes you urinate more. I seriously doubt that happens if you're close to the level of water you need to survive. If your choices are, drink nothing, or drink wine, I'd be very surprised if the answer isn't "drink wine". --Trovatore(talk) 23:03, 27 October 2012 (UTC)

In addition to the concentration of alcohol in the alcoholic beverage, the quantity would also matter. Even with beer, guzzling too much could lead to vomiting and other medical problems which would shorten your life. Sipping it, on the other hand, should sustain your life indefinitely (until you die of malnutrition after many years, at least). I wonder what form of malnutrition would eventually get you. Perhaps rabbit death, due to a lack of fat (although that article says that carbs prevent it, and beer has carbs) ? Also note that some alcoholics do, indeed, have a diet of exclusively alcoholic beverages. StuRat (talk) 23:18, 27 October 2012 (UTC)

I don't question your own experience, Stu, but in decades of consuming beer and wine, I don't recall it ever causing me to vomit. Edison(talk) 01:21, 28 October 2012 (UTC)

I notice people's tendency to vomit varies greatly. I vomit easily, so have never suffered a hangover, and the later effects of food poisoning are minimized. Sure, it's unpleasant, but better to get the poison out of you than leave it in. StuRat (talk) 01:44, 28 October 2012 (UTC)

Oh dear! See Lightweight ;-) Alansplodge (talk) 18:05, 29 October 2012 (UTC)

I like to think that my body is smarter than I am. When I try to ingest poison, it gets rid of it in the most expeditious manner possible. StuRat (talk) 18:10, 31 October 2012 (UTC)

Global remaining Iron and aluminum ore resources

In wind power critical reader comments to articles about wind power in a Swedish magazine I have seen statements that we only have about 10 tones of iron left per person to mine.

Is that really realistic? How about aluminum?

Obviously there are a lot more iron and aluminum in the accessible part of the earths crust since 5% and 8% of the crust is iron and aluminum respectively.

Therefore the real question is how much remaining resources do we have that can be refined to metal to a cost less than let say twice the current production cost?

As I understand it is there much biased information circulating when it comes to estimates of available natural resources. Is there any reliable estimates? Gr8xoz (talk) 12:57, 27 October 2012 (UTC)

Sounds like invented stuff. Comploose (talk) 13:02, 27 October 2012 (UTC)

USGS figures for 2012

• Iron - "World resources are estimated to exceed 230 billion tons of iron contained within greater than 800 billion tons of crude ore."[1]
• Aluminum - not sure [2] but you might find further details at the USGS' site. Or try the BGS' World mineral statistics Sean.hoyland - talk 13:24, 27 October 2012 (UTC)

Thank for your answer!

I are confused about their definition of resource:

"Resource.—A concentration of naturally occurring solid, liquid, or gaseous material in or on the Earth’s crust in such form and amount that economic extraction of a commodity from the concentration is currently or potentially feasible."

What do they mean by "potentially feasible"? At what estimated cost?

230 billion tons is about 33 tone per person, while more than 10 tone per person it is not that much actually, given estimated population increase to 10e9 to 12e9 persons during the next 100 years and increased GNP per capita. Gr8xoz (talk) 16:05, 27 October 2012 (UTC)

I think the Solwara 1 project to mine seafloor for massive sulphide deposits is a good example of where "potentially feasible" is transitioning to "currently feasible" because of the economics and the technology available. Sean.hoyland - talk 16:17, 27 October 2012 (UTC)

Another example that springs to mind to illustrate the difference between potentially and currently feasible is the hugeImouraren uranium deposits. Although the resource was discovered almost 50 years ago, and mining it has been potentially feasible for a long time, the mine won't be operational until next year for all sorts of reasons. Sean.hoyland - talk 16:35, 27 October 2012 (UTC)

Thank you for the link about the Solwara 1 project, it was very interesting, as usual the assesments of the enviromental impact differ very much. It will be interesting to follow.

The limit between "potentially feasible" and not "potentially feasible" is still very fuzzy to me, even the iron core of the earth would be "potentially feasible" if you extrapolate capabilities far enough in to the future and are into science fiction. Gr8xoz (talk) 22:44, 27 October 2012 (UTC)

Even given the low estimate of 10 tones of iron per person, I don't see that as a problem. With recycling, that much should last for centuries, by which time we will be able to mine less accessible sources. StuRat (talk) 00:07, 28 October 2012 (UTC)

Aluminum reserves depend on if you only count Bauxite, or if you count all aluminum ores (aluminum makes up 8.3% of the Earth's crust by weight). --Carnildo (talk) 02:24, 30 October 2012 (UTC)

I know that, see my first post, the question is how much of these 8 % that can be extracted at less than twice the current production cost?Gr8xoz (talk) 17:04, 30 October 2012 (UTC)

That really depends on if there's a breakthrough in processing techniques or not. Anything that makes electricity cheaper, or that increases the variety of usable ores, will increase the amount that can be extracted. Known bauxite reserves are good for at least another century, so it's not a factor that can be ignored. --Carnildo (talk) 01:49, 31 October 2012 (UTC)

Make radioactive material decay faster

Why do you have to wait until radioactive material decays? Isn't any way of just making it decay? Comploose (talk) 13:02, 27 October 2012 (UTC)

No idea about these things at all but is your question related to this article (http://www.businessinsider.com/eu-builds-giant-laser-2012-10)? I came across it earlier and it was referring to a powerful laser that could theoretically destroy nuclear waste. A google search for 'speed up radioactive decay' leads you to a number of science articles talking about this subject. ny156uk (talk) 13:52, 27 October 2012 (UTC)

No there are no known way of speeding up spontaneous radioactive decay. But some radioactive isotopes can be transformed in to stable isotopes by very strong radiation of different types. Gr8xoz (talk) 15:41, 27 October 2012 (UTC)

See Radioactive_decay#Changing_decay_rates for a summary of what is known. As Gr8xoz says, there is no known method of significantly changing decay rates, even in theory, that is both simple and safe and does not involve large amounts of external radiation or enormous power consumption.Gandalf61 (talk) 16:08, 27 October 2012 (UTC)

I still wonder if Förster resonance energy transfer could work on induced gamma emission, though one person's opinion before was "probably not".[3] Wnt (talk) 19:02, 27 October 2012 (UTC)

It took me awhile to find a good link for discussing the lasers-blasting-nuclear-waste issue. Apparently with a high energy laser can transmute isotopes — so you'd try to transmute long-lived iodine-129 into short-lived iodine-128, which then most of the time becomes stable xenon-128. So I guess that's something, if it really works and scales up.--Mr.98 (talk) 19:34, 27 October 2012 (UTC)

• I remember reading something about 10 years ago that indicated a discrepancy had been found in the decay rate of a certain heavy isotope under varying physical conditions. Does this strike a bell with anyone? μηδείς (talk) 19:37, 27 October 2012 (UTC)

There are several references from 1996 to present about an observed effect of physical and/or chemical conditions in the section that Gandalf61 mentioned. Not sure if that is close to the timeframe and/or idea you are remembering. DMacks (talk) 19:43, 27 October 2012 (UTC)

Yes, thanks, I think it was the phenomenon in the fourth paragraph, since I remember it somehow being related to the sun. Apparently it may just be error.μηδείς (talk) 19:48, 27 October 2012 (UTC)

Some papers: [4], [5], and [6]. Zoonoses (talk) 02:38, 28 October 2012 (UTC)

There is a way to decrease a half-life - it involves alloying the radioisotope, and cooling it to extremely low temperatures. I don't remember the constituents of the alloy. Plasmic Physics (talk) 23:54, 27 October 2012 (UTC)

All of the responses so far seem to deal with changing the spontaneous reaction rate. I don't interpret the Q as being limited to that. Why not jam it into a nuclear reactor, and subject it it to whatever dose of whatever type of radiation is needed to convert it into something else, and so on, until you arrive at something stable ? Sure, it's probably not practical, but it is possible. StuRat (talk) 00:01, 28 October 2012 (UTC)

That's the laser idea, more or less. I suspect the problem is that most of the time you will end up with more radioactive material, not less. It's not so much that you'll arrive at something stable by just adding neutrons to it, but you might go from an element with a half-life of a million years to one with a half-life of a few minutes, which then maybe decays into something stable. (So you're actually making it more radioactive, but briefly so.) My intuition though is that in any real-world materials you'll have no net change in long-term radioactivity, since the isotopes will be quite a soup of possibilities. Not to mention the fact that you're probably creating more waste by running the reactor than you're eliminating... presumably this is what the laser scheme is seeking to get around. I'm kind of dubious of it working in practice, but I'm not a nuclear physicist. --Mr.98 (talk) 16:15, 28 October 2012 (UTC)

Battery with unexpectedly high open circuit voltage

Someone I know was working on a device, removed the lead-acid battery and measured its open circuit voltage and got 7.0 V. But it's a nominally 6V battery so it would be 3 cells and each lead-acid cell has a voltage of 2.1 volts so how did the battery give a voltage so much higher than 2.1*3=6.3V? (The battery was apparently defective but they didn't have the equipment to measure its voltage under load, they just replaced it and the device worked so they deduce the battery was bad.) Are there any chemical processes that would occur in a battery that is worn out that would cause a higher open circuit voltage? RJFJR(talk) 14:11, 27 October 2012 (UTC)

For a lead acid battery of the sort used in portable electronic equipment, computer UPS units and other "indoor" applications, the full charge voltage is considered to be 2.35 V per cell (at 25 deg C), not 2.1 V. corresponding to 7.05 V for a nominal 6 V battery. When discharging into a load, a fully charged lead acid battery's voltage rapidly falls to quite close to 2 V per cell and then holds close to that voltage for a comparitively long time, before dropping rapidly as reaches the point of full discharge. Hence the common usage of the terms "6 V", "12 V" etc for 3 and 6 cell batteries.

However, when measuring the voltage of a battery removed from service which may well be nowhere near full charge, you should consider the accuracy of the meter used. A cheap analogue multimeter for instance, may have an accuracy of +,- 3% of full scale. If the range selected to measure is a 10 V full scale range, then the possible meter error in measuring exactly 6 V is 10 x 0.03 = 0.3 V error. So, if you have a reading of 7.0 V, it could actually be as low as 6.7 V without the meter being faulty. Cheap digital multimeters are generally accurate to 1% of full scale or better, with an additional error of plus or minus 1 digit. Seehttp://en.wikipedia.org/wiki/Lead_acid_gel_battery

Keit120.145.36.13 (talk) 15:31, 27 October 2012 (UTC)

The 'cats that look like Hitler' effect?

Along a similar line to black-dog bias, is it true that animal shelters often find it difficult to adopt out cats which facially resemble Adolf Hitler? There was one particular cat in the news last year where this was claimed to be the case. The existence of the http://www.catsthatlooklikehitler.com website would appear to demonstrate that this effect (or at least that people do really notice that some cats look like Hitler) does exist in some form or other...--Kurt Shaped Box (talk) 14:58, 27 October 2012 (UTC)

Surely it looks more like Charlie Chaplin. Wnt (talk) 15:26, 27 October 2012 (UTC)

(e/c)If that was claimed to be the case, why are you asking us? However, all those cats have owners who are presumably perfectly happy with them. Cats look no more like Hitler than they look like Charlie Chaplin.--Shantavira|^{feed me} 15:32, 27 October 2012 (UTC)

I ask because I was wondering if the 'cat thing' had ever been studied to the same extent as the 'dog thing', or if it was only ever really an isolated case that was reported as a widely-known 'fact' in the news... --Kurt Shaped Box (talk) 15:38, 27 October 2012 (UTC)

We have one of those. We call her charlie because we think she looks like Charlie Chaplin. Dauto (talk) 18:03, 27 October 2012 (UTC)

Just in response to Shantavira's 'Cats look no more like Hitler than they look like Charlie Chaplin' point... How's aboutthis one then? --Kurt Shaped Box (talk) 18:45, 27 October 2012 (UTC)

ROFL - it really does! There must be some deep lesson about caricature and facial expressions here. Wnt (talk) 19:04, 27 October 2012 (UTC)

who wouldn't adopt a cat that looks like Hitler? I would, and I think it would appeal to both Nazi and antiNazi both.Gzuckier (talk) 01:53, 29 October 2012 (UTC)

You might name it Lorenzo. —Tamfang (talk) 23:19, 29 October 2012 (UTC)

Is theistic evolution inherently teleological?

67.163.109.173 (talk) 15:50, 27 October 2012 (UTC)

No. Comploose (talk) 16:07, 27 October 2012 (UTC)

Please explain why. Thanks in advance. 67.163.109.173 (talk) 16:16, 27 October 2012 (UTC)

Sorry, a clarification. Specifically, is theistic evolution in the context of an Abrahamic religion that clings to a belief that man (i.e., H. sapiens) is created in (that religion's) God's image, inherently teleological? 67.163.109.173 (talk) 16:31, 27 October 2012 (UTC)

Essentially, yes. Christians believe that God created the universe for a purpose, and theistic evolutionists believe that evlution plays a role in achieving that purpose, so yes, it's inherently teleological. It follows from the nature of the Abrahamic God, who is a person, has a will, and has goals. Dominus Vobisdu (talk) 16:37, 27 October 2012 (UTC)

Shouldn't this be on the Humanities desk? Theistic evolution, Teleology - these are things scientists generally look up on Wikipedia. It seems like there should be some range of possibilities about how specific the purpose might be, but no doubt there is some philosophy that has actually put a name to that? Wnt (talk) 18:53, 27 October 2012 (UTC)

If you believe that God is "guiding" evolution (which is usually what is meant by theistic evolution), then yes, it is inherently teleological (there is a goal or end-point). You could, I guess, claim that God just flips a coin and evolves at random... but that's not what anybody ever means by theistic evolution. If you had a polytheistic religion and polytheistic evolution, I guess I could imagine something that was a little less guided... but again, I don't really see that ever being referred to as theistic evolution. --Mr.98 (talk) 19:36, 27 October 2012 (UTC)

Well, theoretically you can picture a God who says "hey, I want a universe full of really cool stuff, but I want the critters to make up their own minds ... when they hit on something cool I'll know it when I see it". (Not saying that's how it is, but I'm not sure the answer is obvious) Wnt (talk) 19:58, 27 October 2012 (UTC)

But that's not what "theistic evolution" means — every time it is used, it is assumed that God wants humans to eventually show up. That's teleological. You can certainly have a worldview that says there is a God out there somewhere not paying any attention to anything and just saying, "oh, cool, humans" when they evolve without any intervention, but that's not theistic evolution, that's just natural selection with an inattentive deity. ;-) --Mr.98 (talk) 16:11, 28 October 2012 (UTC)

As a Christian agnostic, in as much as I believe God and evolution have any relationship, this is what I believe. There's a metaphysical end towards which events can be said to be driving, but the material world is only subject to its own rules - God doesn't 'prod evolution along' in any sense. By 'theistic evolution', I understand a position in which God does do that, and so physical processes are viewed as teleological. AlexTiefling(talk) 20:47, 27 October 2012 (UTC)

Not an answer, and you might get someone to express this with sources and more clarity on the Humanities desk: There are phenomena such ascarcinisation which hint that Nature, by some means, favors certain recognizable designs, and that evolution does not proceed entirely toward random ends. As the natural laws which favor these shapes in the end are part of an overall structure of logic, it would seem that if this structure is up to God (i.e. that what logically can be deduced from a given set of premises is chosen by God) then those end designs are chosen by God. I note that many people do not think of God as having this sort of power - the power to decide that two and two are three, without otherwise changing or contradicting the rules of mathematics - but it would seem to me that this would be one of the most characteristic powers that define divinity apart from mortal or technological ability. Wnt(talk) 23:42, 27 October 2012 (UTC)

Nature does favor certain things - it's called natural selection... Arc de Ciel (talk) 00:13, 28 October 2012 (UTC)

What's the difference between a) a H. sapiens-shaped God making a universe with laws of physics and initial conditions such that, when left alone for about 13-some billion years without being prodded, little beings that resemble it naturally follow, and b) a H. sapiens-shaped God making a universe with laws of physics and initial conditions not necessarily such that about 13-some billion years later little beings shaped like it naturally follow, but prods along "randomness" such that it happens? Just the point (pre-big-bang or post) at which one considers the act of setting up the dominoes, no?67.163.109.173 (talk) 02:22, 28 October 2012 (UTC)

First of all, the word randomness is a bad word to use. Survival of the fittest is far from random.

If that god is all-knowing then there would be no difference.

The bible would have to be rewritten of course, something along the lines of: "And in the beginning, God created Heaven and Earth, he created some bacteria, called them Adam and Steve, and waited several billion years for them to evolve in a shape similar to his own".They (talk) 03:27, 28 October 2012 (UTC)

Actually, this is a fallacy: an author doesn't live in time dimension of the universe he creates. (George Lucas didn't live during the time of the Galactic Republic) So science can't tell you how long God took to devise the universe, nor in what order he developed the composite elements. Wnt(talk) 04:03, 28 October 2012 (UTC)

Are you saying we are all fictional characters and that reality as perceived by most humans is actually a simulated reality? I like the Matrix too, but I am pretty sure its fiction.

God did not write the bible. Humans wrote it. Some people claim that the people who wrote the bible had divine inspiration, which is weird because it contains many factual errors (e.g. the story about streaked rods and Jacob's goats and the idea that the moon emits light) and major portions of it are plagiarized from earlier works. Different parts of the bible were written by different people, over a period of hundreds of years. SeeOld_Testament#Composition. They (talk) 04:13, 28 October 2012 (UTC) p.s. You may enjoy this video.

My purpose here isn't to argue for Biblical infallibility, but to emphasize that science cannot disprove certain high-order speculations on the nature and origin of the world, specifically whether it is an authored work. Being "pretty sure" The Matrix is fiction is based on what experimental evidence? It is fairly clear that the films indeed are themselves based on religious, specifically Christian ideas. Wnt (talk) 14:01, 28 October 2012 (UTC)

I am sorry, I cannot debate about topics like "What experimental evidence does They have that suggests that reality as experienced by most humans is in fact real and not some kind of simulated reality like in The Matrix" without being stoned. And no, I don't mean that in the Biblical sense, I am referring to recreational drugs. They (talk) 19:45, 28 October 2012 (UTC)

As far as I understand the theory of evolution (not theistic), the randomness is not what is successful, but the randomness is in genetic mutation, which happens, and then if a given mutation just happens to be better suited to the habitat in which the organism exists, and the organism reproduces with more success than other organisms without the random mutation, that random mutation is said to be selected.67.163.109.173 (talk) 04:01, 28 October 2012 (UTC)

That is correct AFAIK. They (talk) 05:02, 28 October 2012 (UTC)

Indeed. Having some mutations is still essential though, since if you didn't have any the organism would never be able to adapt to a changing environment. It's been suggested that if DNA repair were more efficient, this would be selected against for this reason.

Just to throw in another factor: as far as we know, our universe contains randomness at the quantum level. I think a reasonable argument could be made (if you have infinite control at the time of the Big Bang but no intervention afterwards) that there are no initial conditions that could guarantee an outcome as specific as the evolution of Homo sapiens. You could have a particular probability of everything working out in a certain way, but it wouldn't be 100%. Arc de Ciel (talk) 08:00, 28 October 2012 (UTC)

Note that, in accordance with the modern theory and observance of evolution, progressive adaption and evolution is not only dependent on random mutation of ancestral genes, though that is the most common path. It has been shown that co-existent and infective organisms can insert advantageous and disadvantagoes genes into the host DNA. Occaisonally, DNA fragments of something eaten (particularly in single cell organisms or organisms comprising a clump of similar cells, get swallowed up by the cell machinery and incorporated into the cell DNA to be then passed on to daughter cells if it is passive or confers and advantage. It has been shown (described in Scientific American last year as I recall) that this can occur even in humans thought it must occur very infrequently and has obviously in humans no evolutionary significance (only changes in eggs or sperm can be passed on). In some cases, an infective agent multiplies within the cell and gets passed down to daughter cells. Mitochondia, which are essentially compplete parasite organism whithin each cell, confer a very considerable energy advantage to the host. Wickwack 58.169.248.13 (talk) 13:35, 28 October 2012 (UTC)

(Outdenting.) One nice little way to sum up naturalistic evolution is to say that there is random variation but with selective retention. You need both for naturalistic evolution — there has to be a pool of variation that isn't guided, there has to be mechanisms in place to get rid of the non-useful variations. There is "randomness" to it, but it's only half of the equation. In my experience Creationists focus on the "random" and forget about the "selection", hence getting themselves in knot about tornados in junk yards, which is randomness without selection. --Mr.98 (talk) 16:11, 28 October 2012 (UTC)

Mythbusting Mary Poppins

I know that the movie was meant to be a modern-day fairytale and not intended to be realistic at all, but all the same, there are a couple things in it that I think might make for a good Mythbusters episode. So here goes...

1. Umbrella paraglider

I know it's not possible to take off and fly up without a source of power, but is it possible for a fairly slim woman like Julie Andrews to use an ordinary (non-magical) umbrella to glide down by jumping from a height or by sprinting into a strong headwind? If so, given that a typical umbrella has an area of about 16 sq. ft., what would be the stall speed if running into the wind, and what would be the terminal velocity if jumping from a height? Also, if said fairly slim woman with non-magical umbrella was trapped in a burning building, would it be possible for her to escape using this method and survive? (Note that I do not specify that she survive unhurt.) And last but not least, is it true that a woman by name of Mrs. Graham had fallen from a balloon but survived the fall due to her open umbrella and/or inflated skirt acting as a parachute?

I don't see how any normal umbrella could be strong enough to stay concave side down. Read aboutthis fatal attempt from a seventh floor. Also, Mythbustersapparently already busted this myth.[7] Clarityfiend (talk) 21:11, 27 October 2012 (UTC)

So, the bottom line is, it will NOT help survive jumping from a height, as the terminal velocity would still be too high. Thanks!24.23.196.85 (talk) 21:22, 27 October 2012 (UTC)

But then again, what about taking off by sprinting into a strong headwind? (I actually managed to do this, when I was a boy of 14.)24.23.196.85 (talk) 21:25, 27 October 2012 (UTC)

Yes I have experienced this as well, with a very strong umbrella and opening it whilst running.--Gilderien Chat|List of good deeds 21:37, 27 October 2012 (UTC)

You actually lifted off like I did? 24.23.196.85 (talk) 22:14, 27 October 2012 (UTC)

Details from my own attempt: Wind strength was 4 on the Beaufort scale, gusting to 5; I don't remember my own weight, but I couldn't have been very heavy because I was only 14 and slim; I was running as fast as I could, which could have been as fast as 20 mph (I was a fast runner, but a bad starter, and still am); the umbrella's angle of attack at liftoff was about 5 degrees; and the total air time was about 2 seconds, at an altitude of about 1 to 1.5 feet, covering about 10 yards. 24.23.196.85 (talk) 22:24, 27 October 2012 (UTC)

Yes, although not that far. Admittedly it was in the lake district, so there was a "lip" adjacent to the track I was on, causing a very strong upwards current of air.--Gilderien Chat|List of good deeds 00:46, 31 October 2012 (UTC)

There are giant fans pointing upwards which allow a person without an umbrella to hover over them, so, it stands to reason that they could also do so using a properly reinforced umbrella. Of course, her dress would fly up, but we can just consider that a bonus. :-) StuRat (talk) 00:21, 28 October 2012 (UTC)

Even more exciting with a proper fox frame and a sufficiently powerful vortex generator I see no reason Nanny may not make it beyond the atmosphere. But perhaps a space fountain would be a better idea. It could be set up to work through the chimneys, and could draw her up by a suitable rare earth magnet in her carpet bag. Rich Farmbrough, 01:16, 28 October 2012 (UTC).

Great ideas, everyone! (Well, except she wouldn't be able to pass through a chimney, as it's only 13" by 9".)  :-D 24.23.196.85 (talk) 01:55, 28 October 2012 (UTC)

You may be interested in the story of Sarah Ann Henley. --TammyMoet (talk) 10:08, 28 October 2012 (UTC)

Wow, what an amazing survival story! BTW, a typical woman's skirt would have a surface area of about 20 square feet -- still not enough to survive a landing on a hard surface, but enough to give a fighting chance of surviving a soft-surface impact (as was the case here). 24.23.196.85 (talk) 02:07, 29 October 2012 (UTC)

Do you base your calculation on a typical crinoline skirt of the era, or a typical modern skirt? Just curious. Some crinolines took a huge amount of material. --TammyMoet (talk) 09:36, 29 October 2012 (UTC)

BTW, does anyone have any details on Mrs. Margaret Graham the balloonist, and how exactly she survived a 100-foot fall from her balloon? I've read that she survived because her dress flew up and acted like a parachute (similar to what happened with Sarah Ann Henley), but I can't verify this info and Wikipedia has no article about her at all. 24.23.196.85 (talk) 02:30, 29 October 2012 (UTC)

For glinding with an umbrella, read Erich Kästner's The Flying Classroom, which shows it doesn't work. Of course, this is a work of fiction, but it's worth to read anyway. – b_jonas 22:36, 29 October 2012 (UTC)

2. "Posts, everyone!"

When Admiral Boom fires his cannon, would the resulting seismic wave smash the neighbors' crockery and other fragile items, and if so, within what radius? More to the point, is it possible for this to happen without the airborne shockwave also blowing out all the windows?

24.23.196.85 (talk) 20:54, 27 October 2012 (UTC)

A sound wave could do this, provided it was at the resonant frequency of those items it broke. However, this is extremely unlikely, as that would require a lot of energy at a very high frequency, and that's not something a cannon is likely to create. StuRat (talk) 00:17, 28 October 2012 (UTC)

24.23.196.85 (talk) 20:54, 27 October 2012 (UTC)

If crockery is sufficiently finely balanced any shock wave could cause it to rattle or fall to the floor. Rich Farmbrough, 01:09, 28 October 2012 (UTC).

I remember reading that a 19th century British coastal artillery battery (possibly Coalhouse Fort in Essex) used to send a soldier round to the neighbouring houses before practice firing, to tell them to open their windows in case they were broken by the blast. I've just had a look for a reference, but could only find this account (last page) of coastal artillery in action at Weymouthin 1940; “A suspect vessel disregarded recognition signals and so No.1 gun of the fort was ordered to fire a shell across its bows. This gun misfired and so No. 1 gun of the Breakwater fort was so ordered. The shell ricocheted off the water in front of the vessel, passed between it’s masts and headed on for Lulworth! The vessel failed to stop, arriving safely in Weymouth Harbour to disgorge French troops who had fled Dunkirk. The blast from the gun shattered all the windows in the Sapper’s barracks on the Breakwater.” I believe the gun in question was a BL 6 inch Mk VII naval gun, rather larger than the signal cannon in the film. Alansplodge (talk) 01:21, 28 October 2012 (UTC)

Thanks for the input, everyone! So I gather that the effect would most likely be the opposite -- the windows would shatter, but the crockery would probably remain intact unless precariously balanced? 24.23.196.85 (talk) 01:57, 28 October 2012 (UTC)

Most often, yes. StuRat (talk) 02:00, 28 October 2012 (UTC)

Collars for control knobs

Control knobs that go on spindles with (or indeed without) a flat sometimes have a steel collar around the part of the knob that slips on to the spindle. (I worked on a machine that put these on a component for central heating thermostats many years ago, which was interesting in its own right for several reasons.) So two questions, what are these collars called, and where can they be obtained? Rich Farmbrough, 18:08, 27 October 2012 (UTC).

In the electronics industry, there are two kinds of knob (apart from knobs that do not have a metal insert and are force fitted): ones with metal inserts that provide a strong base to put a threaded hole into for a retaining grub-screw, and one s with metal inserts that are longitudinal split, with a peripheral thread thread cut. A nut screwed on this thread progressively compresses the split insert onto the control shaft. The actual knob, cast in plastic, in both types conceals the metal parts. In both cases the metal insert is usually brass and is called a collet - however, when an electronic engineer calls for acollet knob, he usually has the second type in mind. If he wants a grub-screw knob, he'll usually say he wants a grub-screw. The more widely known use of the word collet is in machines and machine tooling. See http://en.wikipedia.org/wiki/Collet. You may like to google collet knobs. Perhaps you had this sort of thing in mind.

However, there is a another common type that has a plated or passivated spring steel collar or ring that surrounds a molded split part of the knob to clamp it onto the shaft. This type is more common in Asian-made equipment. In this case the metal part should be called a compression ring or compression spring.

You can obtain control knobs from suppliers specialising in electronic parts. RS Components and Element 14 both have a good range and have stores in many countries. Keit 121.221.226.4 (talk) 02:20, 28 October 2012 (UTC)

Ah thank you! The word I was searching for was collet but what I actually meant was compression spring. And I have the knob (which is a friction fit, rather than force fit) I just want to reinforce it with a compression spring - if possible. Rich Farmbrough, 03:05, 29 October 2012 (UTC).