Wikipedia:Reference desk/Archives/Science/2007 December 6

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December 6

F-35 questions

Looking at the recently released information of the F-35 engine failure in May, is it possible to install a ram air turbine on the F-35? Also, why is there no trainer version? And why no two-seat version? --Blue387 (talk) 01:10, 6 December 2007 (UTC)

You would probably do better asking over at the F-35 talk page, but if I was to guess I would say "weight concerns". Astronaut (talk) 01:59, 6 December 2007 (UTC)

I would actually say the science desk is the better place to ask, as it's much more heavily trafficked than most talk pages. Someguy1221 (talk) 04:06, 6 December 2007 (UTC)

Agreed. Talk pages are for discussing the article, not the topic of the article. -- HiEv 12:11, 6 December 2007 (UTC)

I don't think it's weight. They could quite easily take out a few hundred pounds of fuel to compensate - you don't need long range capability for training missions. No - the real reason is that it costs a lot of money to design, build and certify a two-seat version of a plane that's intended to be single-seat-only in actual mission usage. They might only ever make a dozen of the two seat version - which means there is no economy of scale. In the past, there was little choice in the matter since you had to have some way to teach people to fly the darned thing. On the F22 program, they planned some two seat varients - but cut them from the program to save money. For both the F22 and F35, it was decided that flight simulator technology was sufficiently good that pilots could go straight from other aircraft types (F16, F18) for which two-seat variants exist to flying solo in an F35 - with only simulator time used for the transition. Since they need good simulators anyway - it's much cheaper to do that than to design and build two-seaters that are effectively useless for actual missions. I was the lead graphics engineer for the F22 and F35 simulators - and it was quite a proud moment to understand the that simulators have attained to become so well accepted by the military. Incidentally, civil airlines are routinely allowed to have pilots transition from one aircraft type to another using "zero flight time training" (ie simulation) - and they've been doing that for at least 20 years. So the pilot on your next flight could easily be on his first ever trip in that kind of an aircraft! SteveBaker (talk) 03:30, 6 December 2007 (UTC)

I believe it's possible to get a complete type rating from simulator time alone. In a recent "Flying" magazine article, one of the regular contributors (a surgeon by trade) who only flies a twin engine Beechcraft, received his Boeing 737 type rating without leaving the ground. (Type ratings are all that is required for turbine and airplanes greater than 12,500 lbs beyond the "Airplane, multi-engine, land" rating. So to go from a twin engine, six seat, propeller Beechraft to a 4 engine boeing 747 is a type rating. No airline would let you fly it, but you can get the legal ability to do it and all you need is sim time). --DHeyward (talk) 04:14, 6 December 2007 (UTC)

Yes - from a multi-engine rating, I think it's possible. It's been a long time since I last did civilian simulation - but that's a much easier job than simulating a modern fighter. The fidelity of even a 20 year old 737 simulator is really close to 100% and training on a simulator is so much cheaper and safer than flying a real plane that flight hours logged in a sim are actually more valuable than on the actual aircraft. In the simulator you can toss up fault conditions, singly and in combination, fly at night and in fog, you can bring in other aircraft on converging or colliding courses and practice at airports from all around the world without going there...all manner of things that you can't possibly do in a real plane. SteveBaker (talk) 04:55, 6 December 2007 (UTC)

No two seat version, because that's what the F-22 is for. The F-35 is a smaller, STOVL version of the F-22 essentially. The F-35 is a smaller, navy fighter, while the F-22 is a larger airforce fighter. 64.236.121.129 (talk) 14:32, 6 December 2007 (UTC)

But there isn't a two seat version of the F22 either - that was to have been the F22B but it was cancelled in 1996 or so (probably when they saw how good our simulator was!) SteveBaker (talk) 18:08, 6 December 2007 (UTC)

Actually, the F-35 is a multi-service fighter (with distinct Air Force, Marine, and Navy versions) intended to fill a role separate from that of the F-22. For the Air Force, the F-35 fills a role akin to that of the F-16, while the Navy and Marines will use it to replace F-18s (though not the E/F Super Hornets). Only the Marine variant has STOVL capability. — Lomn 15:48, 6 December 2007 (UTC)

Anyway, not having seen a discussion of the RAT specifically, here's what I've dug up: The F-35 uses an IPP, or Integrated Power Package for auxiliary and emergency power, which seems to negate the need for a RAT. The article linked notes that the F-35 is moving towards "more-electrical" components like this one to save weight, improve reliability, and improve packing efficiency (that is, you don't have to put it where it can deploy into the airstream). I haven't run across the details of the May engine failure, though, so I can't offer much as to the specific implications for that incident. — Lomn 16:04, 6 December 2007 (UTC)

atomic number

how do they know how many protons are in an atom? How did Mendeleev know the atomic masses of the elements in his periodic table?70.171.229.76 (talk) 03:00, 6 December 2007 (UTC)

They have little teeny eyes

For seeing little teeny things

Like you need little teeny license plates for bees

With apologies to whoever it was that Larry Niven copied it from. --Trovatore (talk) 02:54, 6 December 2007 (UTC)

...oh, by the way, it actually is a good question, and I don't know the answer off the top of my head. It just made me think of the song. --Trovatore (talk) 03:03, 6 December 2007 (UTC)

The number of protons has to equal the number of electrons in an electrically neutral atom. So the question is really "how do they know how many electrons there are in an atom". Sadly, I don't know the answer to that either - but I bet it's a lot easier to answer! SteveBaker (talk) 03:05, 6 December 2007 (UTC)

Mass is easy. They used scales! They do a titration or something to know how much stuff there is and then weigh it. That mass divided by number molecules is the mass of the molecule. The number of protons would have been determined first ionising the atoms completely and finding their mass/charge ratio in a mass spectrometer Shniken1 (talk) 03:35, 6 December 2007 (UTC)

The periodic table was invented before the concept of an electron as a discrete particle. They didn't have mass spec or the ability to fully ionize heavy atoms. The original periodic table was based on shared chemical properties and increasing mass, not number of protons. For example, unreactive gases (e.g. noble gases) formed one column. They did have a rudimentary concept of valence based on how chemicals combined, so they could place alkali metals and halogens in their columns, etc. But the largest determining factor in the overall ordering of the original table was mass. Dragons flight (talk) 05:12, 6 December 2007 (UTC)

My point is that you can't use mass alone because you can't tell the difference between the mass of a proton and a neutron with any degree of precision. So if they had been using mass alone, they wouldn't have been able to tell the difference between (say) Pb²⁰⁵ and Tl²⁰⁵ (that's a bad example because lead-205 is very rare - I'm sure there are better examples) - and they'd have been unable to set things out neatly using mass alone. You need to look at how the elements react together to get an idea for valences - which in turn relates to the number of electrons/protons. However, you can almost guess where each element belongs in the table by examining it's properties - metals on the right, non-metals on the left. Reactivity rates increasing across the rows, similar chemistry down the columns... that's the kind of thing that would let you know if you had two elements in the wrong order...not mass. SteveBaker (talk) 17:57, 6 December 2007 (UTC)

Perhaps a better example would be tellurium and iodine, which have atomic masses 127.6 and 126.9, respectively. Sorting by mass puts them in the wrong order (compared to atomic number) due to a high natural abundance of the heavier tellurium isotopes, and indeed I believe they were originally switched on early attempts at periodic tables. However, examining their chemistry clearly shows that iodine is a halogen and belongs in group 7. --Bob Mellish (talk) 19:07, 6 December 2007 (UTC)

Mendeleev would have had no notion of isotopes or anyway to get elements in any masses other than the naturally occuring mixture. Natural masses gives you the right ordering for all but 3 naturally occuring elements. His insight was actually to arrange groups and predict gaps where elements hadn't been discovered based on chemical properties, but figuring out the overall ordering is easy on the basis of mass alone. Dragons flight (talk) 19:03, 6 December 2007 (UTC)

According the Wikipedia's article on Dmitri Mendeleev, he created the table from known atomic masses and properties (discovered by other scientists). In fact, his table was capable of predicting the masses of not yet discovered elements. You can read more about Mendeleev's Periodic Table. (EhJJ) 03:46, 6 December 2007 (UTC)

By shooting electrons onto a sample of the element in question, one obtains x-rays. The spectrum of these x-rays is composed of a continuous portion (bremsstrahlung) and characteristic lines. By measuring the characteristic lines the effective nuclear charge can be determined (the charge affecting the innermost (1s) electrons, generating energy levels similar as in the hydrogen atom, but at higher energies). The effective nuclear charge is approximately Z-1, where Z is the number of protons (and if this is not accurate enough, neighboring elements in the periodic system have always an effective nuclear charge differing by approximately 1, so you can make the measurements for many elements until you have a complete series up to the element in question). Icek (talk) 05:07, 6 December 2007 (UTC)

Another method is using the Geiger-Marsden experiment: The number of deflected particles from a "monochromatic" (all particles have got the same energy) alpha source is proportional to the nuclear charge if everything else (like the thickness of the foil in atomic layers) is equal. Icek (talk) 05:20, 6 December 2007 (UTC)

To determine relative atomic masses you make careful measurements of the relative masses of different elements as they participate in a range of different chemical reactions, then you apply the law of multiple proportions (that's not a great WP article, because it reads like a chunk from a textbook, but it does illustrate the law with various numerical examples). Chemists like John Dalton were determining relative atomic masses at the beginning of the 19th century, many years before anyone even postulated the existence of protons, neutrons or electrons. Gandalf61 (talk) 13:43, 6 December 2007 (UTC)

I'd like to draw attention to the fact that this edit providing the majority of the multiple proportions article appears to have copied it from this book, which is under cc-by. I'm not an expert at how to give the appropriate attribution, but something clearly needs to be done about it. --Tardis (talk) 16:41, 6 December 2007 (UTC)

How does the nuclear binding energy (mass defect) compare to the difference between proton and neutron masses? HRMS can pretty easily distinguish between different element combinations that have the same integral mass ("number of nucleons"), so given a nuclear mass with enough precision, could one determine what specific combination of protons and neutrons gives it? DMacks (talk) 18:29, 7 December 2007 (UTC)

For ²H, nuclear binding energy is about twice the ¹p⁺ vs ¹n⁰ mass difference, I guess this isn't gonna work in many cases:( Yup, two minutes in the library saves a lot longer and megabucks of lab-work. DMacks (talk) 18:33, 7 December 2007 (UTC)

ring finger

Why is it hard to stick only your ring figer up. or to do that thing from star trek where your fingers look like \\// .thanks--Sivad4991 (talk) 03:02, 6 December 2007 (UTC)

It's odd - but some people have problems with that and some don't. I can do both of those very easily. Another one is the ability to raise one eyebrow and not the other. Yet another is to have one big toe point upwards and the other downwards - then to switch them both - then to alternate rapidly between the two such that one toe is always up and the other down. I think it's simply that these are things that we never normally need to do - and therefore get very little practice at. I kinda suspect that if you don't do them as a kid, some neural pathways don't form - then it's very tough to learn how to do it as an adult. I know my son couldn't do the "Live long and prosper" Vulcan salute thing when he was 10 years old - but managed to learn how to do it. There are some of these things (like rolling your tongue into a tube) that have actually been studied rather carefully - but I have to say that the results aren't exactly convincing. SteveBaker (talk) 03:14, 6 December 2007 (UTC)

Another one, most people can pat their head and rub their stomach, but can't do the opposite. —Preceding unsigned comment added by Shniken1 (talk • contribs) 03:30, 6 December 2007 (UTC)

From ring finger, "It is the weakest of the fingers on the hand, as it shares a flexor muscle with the middle and little fingers. It is the only finger that cannot be fully extended by itself separately." This is as much as I suspected, "something wierd about muscles." Someguy1221 (talk) 04:08, 6 December 2007 (UTC)

fully extend - no but 'stick it up' - yes. SteveBaker (talk) 04:43, 6 December 2007 (UTC)

Place one hand on the underside of your forearm about 60% of the way toward the hand. Now open and close your other hand. You should feel the muscle base pulling the tendons that go up through your hand to manipulate your figures. (Your fingers are essentially moved by wires anchored in your forearm.) The muscles that move adjacent fingers are partly connected so when you attempt to close or extend one finger you often end up manipulating adjacent fingers. It is possible with training to significantly increase the degree of independent movement. Such training is a common element of some dance styles, particularly those from the Indian subcontinent. Dragons flight (talk) 05:22, 6 December 2007 (UTC)

I used to have problems moving my fingers independently but playing the piano helped me to 'train them to move independently although my ring finger and little finger still want to move together a bit. The same goes for playing a different tune with the right and left hands, it's very difficult but practice makes perfect. As for the patting your head and rubbing your stomach, I can do it both ways round although it takes some practice and coordination! Some people can also wiggle their ears but I've never been able to do that. I think a lot of the reason is that muscles are very weak unless they actually get used, as most people have no need to wiggle their ears or precisely control their little finger, we perhaps 'forget' or don't learn how to use them in the first place? GaryReggae (talk) 11:59, 6 December 2007 (UTC)

variable frequency drive

at the inverter section, what will happen if one of the igbt's component short out or opens? —Preceding unsigned comment added by 70.251.116.191 (talk) 04:08, 6 December 2007 (UTC)

What exactly are you talking about? Power supplies? Amplifiers maybe? It's hard to tell! SteveBaker (talk) 04:41, 6 December 2007 (UTC)

Any short in a transistor in the bridge circuits of a variable-frequency drive will usually blow a fuse (and maybe the "other" transistor in that half-bridge). It's harder to assess what will happen for an "open"; an already-running motor may keep running, but will commonly overheat. A stopped motor probably won't start on the remaining two phases. In either case, a good VFD will recognize that something is wrong and shut down.

Atlant (talk) 13:15, 6 December 2007 (UTC)

Overloading an IGBT is very likely to vaporise it and the surrounding circuitry, so that you will not be able to determine what caused the failure. Good luck if you are operating without protection. Graeme Bartlett (talk) 20:32, 6 December 2007 (UTC)

Vaporize? Not if it's fused properly. And I speak from direct experience here.

Atlant (talk) 23:49, 6 December 2007 (UTC)

cosmic microwave background radiation

Are the photons of CMBR gravitationally lensed? —Preceding unsigned comment added by 203.192.230.107 (talk) 08:39, 6 December 2007 (UTC)

Cosmic microwave background radiation mentions this and cites a published article from 2006. --JWSchmidt (talk) 14:17, 6 December 2007 (UTC)

I do belive they are but the mass distribution between here and the edge of the observable universe is approximately even so it all almost cancels out with a few anomalies.Thomashauk (talk) 21:36, 11 December 2007 (UTC)

Faraday cages

I've read some Wikipedia articles related to Faraday cages. I'm not sure if I have understood correctly but, do they mean it is impossible to build a Faraday cage that cancels every incoming electromagnetic wave (because each skin depth nullifies a definite range of frequencies)? --Taraborn (talk) 11:57, 6 December 2007 (UTC)

A given Faraday cage is effective over a range of frequencies. At the high frequency end, it's (usually) pretty simple: the size of the openings, if any, must be quite small compared to the wavelength you're trying to exclude; the rule of thumb is to keep openings smaller than a quarter wavelength. At the low frequency end, I'm not quite sure, but it seems to me that there's no problem excluding the electric field but that the exclusion of the magnetic field requires increasingly good conductivity as the frequency goes lower and lower (because the Faraday cage must conduct an opposing current, creating an opposing magnetic field). A superconductive Faraday cage would probably exclude the magnetic field right down to DC (see the Meissner effect), but non-superconductors must have a practical lower limit (combined with an attenuation factor).

I'm not sure "skin depth" comes into play directly, though.

Obviously, I hope someone comes along who can offer a more-concrete answer to your question.

Atlant (talk) 13:24, 6 December 2007 (UTC)

Thank you for your response. Let's see if somebody else has something to add. --Taraborn (talk) 14:52, 6 December 2007 (UTC)

Skin depth comes into play with the low frequency end. If your shield has only a few skin depths of thickness then some fields will penetrate, so for audio frequencies you may have to use thick layers of metal. Graeme Bartlett (talk) 20:38, 6 December 2007 (UTC)

Plasmon frequency again?--TreeSmiler (talk) 02:37, 7 December 2007 (UTC)

Purple sky

A few days ago, the sky turned purple, during the day. Why is this? It was not sunset.

(Sorry to link to this place but it was exactly what was seen). Photo from flickr 147.197.229.134 (talk) 14:36, 6 December 2007 (UTC)

Purple is a mixture of red and blue. Towards dawn or dusk, the sunlight is red but the sky away from where the sun is shining is blue. Generally, these colours stay in their own parts of the sky and don't bother each other - but just the right kind of a layer of thick cloud between you and the sunset can diffract and mix the light together - resulting in reddish sunlight and blue from the sky being mixed into this purplish colour. SteveBaker (talk) 16:54, 6 December 2007 (UTC)

This photo was quite obviously taken at night (buildings are dark with indoor lights coming through the windows). My guess is that it's a photograph of lightning. (EhJJ) 20:26, 6 December 2007 (UTC)

I'm the photographer of that photo (my site logs pointed me here!), and I can tell you it was taken at 4pm on the 4th December, in mid-Norfolk, UK. It was dusk at the time - and certainly no lightning! I took a similar photo at a similar time almost a year ago too: link to more purple sky.--DeKay01 (talk) 22:07, 6 December 2007 (UTC)

So why did our questioner say "It was not sunset"?? On December 4th in London, sunset time is 3:58pm and the photo was taken at 4pm. At sunset, no other explanation is needed than the one I gave above - red+blue=purple. QED. SteveBaker (talk) 23:42, 6 December 2007 (UTC)

I interpreted the questioner to mean that the photo is an example of what he saw, but perhaps not exactly what he saw. The IP seems to come from the Univerity of Hertfordshire and my UK geography is woefully lacking - is that near mid-Norfolk, where our photographer was? --LarryMac | Talk 23:52, 6 December 2007 (UTC)

A similar picture taken of a lightning strike. (EhJJ) 01:28, 7 December 2007 (UTC)

Seems to me like SteveBaker is probably right about the reason. Sorry if it seemed like I was jumping to a conclusion, but it looks a lot like this photograph (right) that I took a few months ago; the image the OP linked is in no way taken in the middle of the day. (EhJJ) 01:28, 7 December 2007 (UTC)

The photo the OP linked to was mine, taken at 4pm on the 4th December. However, the OP seems to be using it as an example of what he saw - so he may well have seen the same sort of thing earlier in the day. Mid-Norfolk is about 100 miles N/NE of Hertfordshire. --DeKay01 (talk) 07:40, 7 December 2007 (UTC)

Obviously, the further north you go, the earlier sunset will be - and the longer it will last. The 3:58pm sunset time on Dec 4th was what I looked up for London. Also, sunset is defined as the time the upper rim of the sun drops below the horizon - there will be a lot of red light in the sky for a long period before that. The amount of cloud cover serves to diffuse the light - so it might not be obvious to people observing the effect that they are actually looking at the consequences of the sun starting to set. I think the OP may merely be surprised that the sky was actually turning red (behind the clouds) so early in the day. SteveBaker (talk) 16:33, 7 December 2007 (UTC)

How well do battery electric cars perform under cold and hot temperatures?

Topic says it all. 64.236.121.129 (talk) 15:56, 6 December 2007 (UTC)

I find very little discussion of significant problems with nominal temperature extremes. I would hypothesize that, should efficiency problems be severe enough, it would be no big deal to heat or cool the battery compartment along with the passenger compartment. — Lomn 16:14, 6 December 2007 (UTC)

My understanding of lead-acid batteries is that they have trouble delivering a large current in cold temperatures (think of starting your car on a cold day), but the cold temperatures do not cause permanent damage. Hot temperatures, on the other hand, do not cause immediate problems, but do shorten the lifetime of the battery. I don't know about other battery types in this regard. -- Coneslayer (talk) 16:39, 6 December 2007 (UTC)

(old answer deleted - I didn't notice "electric cars"!) SteveBaker (talk) 16:57, 6 December 2007 (UTC)

As far as cold temperatures are concerned, you get mixed messages. This page claims that there are no problems and quotes a study done by REV Consultants. The REV Consultants page explains that the test was on a battery heating system to keep the battery from getting too cold. So, you have one person saying that batteries work just fine in the cold and another marketing a battery heating system so they don't get too cold. -- kainaw™ 17:20, 6 December 2007 (UTC)

If you'll accept a practical example, the battery pack in the Toyota Prius hybrid car is air-cooled using a fan. So Toyota's designers clearly considered that higher temperatures were bad for the long-term health of the battery. The problem on the cold side is that aqueous electrolytes all have some freezing point and the amount of charge in a battery can affect that; for example, for a lead-acid battery, the electrolyte becomes more- and more-pure water as the battery is discharged, leading to the possibility of the battery freezing at a mere 0°C if the battery is dead flat.

Atlant (talk) 17:28, 6 December 2007 (UTC)

Doesn't the Prius have a Nickel-Metal Hydride battery? Heat is definitely bad for NiMH batteries it reduces cycle live (hence the reason you're supposed to keep them cool and why fast chargers can be bad) and increases self discharge. On the other hand, performance does drop with temperature and although you can use them below freezing you generally can't charge them. At least according to [1] (which discusses several batteries types) Nil Einne (talk) 12:40, 11 December 2007 (UTC)

Yes, NiMH for the "hybrid" battery in the stock, current-production Prius. (Plug-in mods vary all over the spectrum from Lead-Acid to Lithium Ion.) The Prius also contains a conventional 12V lead-acid cell for ordinary 12V needs, but I certainly didn't intend to imply that the Prius's main energy-storage battery was lead-acid, I just used that chemistry as the most-obvious example of a battery that has problems in the cold.

Atlant (talk) 13:54, 11 December 2007 (UTC)

Floppy McDonald's Fries

How can one make fries floppy like at McDonalds? I know they're supposed to be crispy or whatever, but I like them when they're floppy. What goes "wrong" to make 'em good 'n' floppy? --Seans Potato Business 16:18, 6 December 2007 (UTC)

Less frying time gets you softer fries. More time makes em cripsy. Friday (talk) 16:24, 6 December 2007 (UTC)

For home fryer use, a single fry is a good way to make floppy fries. For crispy-but-not-burned, a double fry is advocated -- once to cook, and once at a higher temp to crisp. Professional jobs use a different method, but I forget what it is offhand. — Lomn 16:32, 6 December 2007 (UTC)

It is called Blanching. --Mdwyer (talk) 20:21, 10 December 2007 (UTC)

BTW, as far as I'm aware most fries you can purchase are pre-fried so you usually only need to do this with fries that you cut yourself (although I'm sure you can get fries which are not pre-fried). Similarly for that matter most commercial fries are pre-fried too, the actual McDonalds/whatever chain only has to fry them once Nil Einne (talk) 12:32, 11 December 2007 (UTC)

I suspect that some floppy fast-food fries are the result of them sitting under a heat lamp for a while before they are served. -- Coneslayer (talk) 16:37, 6 December 2007 (UTC)

Does Ball Lightning have an charge?

Can it be affected by magnetic fields? 64.236.121.129 (talk) 18:32, 6 December 2007 (UTC)

Since the nature of ball lightning remains unknown, no definitive answer can be given to these questions. — Lomn 19:00, 6 December 2007 (UTC)

It's not at all clear that ball lightning is in fact a real phenomenon. They have not been produced artificially - and the conditions under which they are supposed to have arrived in nature is poorly described. There is no reasonable way in which a ball of electrical charge could be stable for seconds to minutes as claimed. I'm utterly horrified at our article Ball lightning which shows a short movie clip of "Ball lightning seen here following a car" which is quite obviously a reflection of the sun on a wet road that appears to be chasing the car because the camera is in a moving helicopter. If they were indeed real (and I'd put the probability down at one in a hundred that they are) then if they are (as claimed) electrical in nature - then magnetic fields ought to affect them...but as I said...they are about as real as UFO's aren't. SteveBaker (talk) 19:03, 6 December 2007 (UTC)

The article seems to indicate that they are real, and the skeptics are in the minority now. Maybe they just aren't completely understood yet. 64.236.121.129 (talk) 19:10, 6 December 2007 (UTC)

I think there's room for discussion as to what constitutes "real". Are there some phenomena that are real? Absolutely. Is there any one phenomenon that we can identify as "ball lightning" to the exclusion of all others, apart from arbitrarily saying "This is 'ball lightning'"? Perhaps not. If the latter holds, then I think it's fair to say "Ball lightning isn't real", even if there are phenomena that partially resemble descriptions of ball lightning. — Lomn 19:41, 6 December 2007 (UTC)

A load of ball (lightning) or not? [2]--TreeSmiler (talk) 03:13, 7 December 2007 (UTC)

There is a lot of difference between that (which is a ball of burning silicon gas/particles) and ball lightning. Sure, you can get small balls of burning gas under rather special laboratory conditions...nothing too remarkable about that. It's the claims for electrical effects that are dubious. SteveBaker (talk) 16:27, 7 December 2007 (UTC)

I just remembered the name of the phenomenon of burning gas balls that I've been wracking my brain trying to remember since the start of this thread! See Will-o'-the-wisp - little balls of methane that spontaneously ignite after bubbling up from rotting vegetation in marshland. The reason for ignition of the gas is poorly-understood - but once ignited, there is not much mystery. I strongly suspect that something like Bubble fusion is involved - not necessarily actual fusion but a dramatic increase in temperature as bubbles collapse. Since the methane is very unstable in air, it wouldn't take much of a spark to set it off. But it's still not ball lightning - just a more reasonable phenomenon that might explain many of the supposed sightings. SteveBaker (talk) 16:47, 7 December 2007 (UTC)

Ah, and that's where we differ. I'd say it is ball lightning, since that is the term used to describe it. That this term includes the word 'lightning' which implies it has a lot in common with normal lightning is just an historical accident, revealing what people used to think they were. After all, we can talk about Will-o'-the-wisps being 'real' without implying there's any 'will' behind them or that there are little people with lamps guiding travellers to their doom. It's the old thing of not discarding data points that don't fit, but also not necessarily buying the explanations people offer for them. If a lot of people report seeing ball lightning which appears to respond to electrical fields, then that needs to be noted. It might be that it's all an illusion, in which case learning that is good. It might be that it's something else, in which case you've avoided throwing knowledge away. After all, rains of fish were once dismissed as fanciful. Skittle (talk) 18:39, 7 December 2007 (UTC)

Can palms grow in Switzerland and the UK?

Cabbage trees (aka "Torbay Palms") growing in Torquay, England

Hi! I once read that palms can naturally occur in the southernmost parts of Switzerland and in south of England. Is that true? --escondites 18:37, 6 December 2007 (UTC)

From the article Arecaceae (you can find the link in Palm): "The northernmost palm is Chamaerops humilis, which reaches 44°N latitude in southern France, where the local Mediterranean climate is milder than other places as far north." -- kainaw™ 18:48, 6 December 2007 (UTC)

Well, yes...and no. So-called "Cabbage trees" are reasonably cold-tolerant and can be grown in the south-west of England in places with an especially good microclimate such as Torquay. They look an awful lot like palm trees and are sometimes called "Torbay Palms" (although technically, they are not palms at all). Switzerland is considerably further south - so in low-lying areas, it ought to be possible to grow them there too. I don't think true, honest-to-goodness palms do actually grow in England though - but I can't speak for Switzerland. SteveBaker (talk) 18:56, 6 December 2007 (UTC)

Here (http://www.thepalmcentre.co.uk/palms.htm) suggests yes some forms of palm can. Is true ny156uk (talk) 22:44, 6 December 2007 (UTC)

Trachycarpus fortunei has been cultivated in gardens and parks of the Swiss canton of Ticino for hundreds of years - the ones skirting the promenade along the Lago Maggiore, for example, belong to Locarno's touristic trademark. For the past 30 years or so, they have started to grow wild and naturally as an introduced species in the Ticino too. Biologists have studied this trend and linked it to climate change. I remember reading about it in Swiss papers a couple of years ago. International press centre biodiversity research has some information in English. ---Sluzzelin talk 00:50, 7 December 2007 (UTC)

Palms do grow in parts of Cornwall. Bananas can be grown there too, and indeed were in the war. DuncanHill (talk) 00:55, 7 December 2007 (UTC)

Trebah has palms, see [3] for some pics and binomials. DuncanHill (talk) 00:57, 7 December 2007 (UTC)

But can they grow "naturally", i.e. in competition with native species, in southern England? ---Sluzzelin talk 01:03, 7 December 2007 (UTC)

England I dunno, Cornwall I'd say yes, in some places. DuncanHill (talk) 01:06, 7 December 2007 (UTC)

Please forgive me, I meant Great Britain. ---Sluzzelin talk 01:10, 7 December 2007 (UTC)

You are forgiven (on production of one saffron cake), tho' I'm still not happy with your spelling preferences in -ise/-ize :)DuncanHill (talk) 01:20, 7 December 2007 (UTC)

Uh, what are you guys apologizing and forgiving about? Cornwall is in southern England, which is part of England, which is part of Great Britain. --Anon, 01:27 UTC, December 7, 2007.

There's a bit of a 'Free Cornwall' movement. Maybe we should just all split into subcountries and see how that improves things... Free Cotswolds! 79.69.14.132 (talk) 02:08, 7 December 2007 (UTC)

Scilly Isles Also Scotland [4]

—Preceding unsigned comment added by TreeSmiler (talk • contribs) 02:26, 7 December 2007 (UTC)

What's the largest supermassive black hole that we know of?

^Topic 64.236.121.129 (talk) 18:57, 6 December 2007 (UTC)

http://www.google.com/search?q=largest+black+hole suggests the core of galaxy M87, at 3 billion solar masses. — Lomn 19:49, 6 December 2007 (UTC)

Hmm, that's not the largest. Q0906+6930 is larger at 16 billion solar masses, but I don't think it's the largest we know of. 64.236.121.129 (talk) 20:54, 6 December 2007 (UTC)

Mosquitoes the size of birds

Most places with significant numbers of mosquitoes also have tall tales of the exploits of their extra-large mosquitoes -- carrying off small dogs, biting people through the walls of houses, and the like. Which area really has the world's largest mosquitoes? --67.185.172.158 (talk) 19:50, 6 December 2007 (UTC)

A number of references cite mosquitoes of the Toxorhynchites genus as the largest mosquitoes. Toxorhynchites larvae are known to feed on the larvae of other mosquito species. The adults are gentle and peace-loving (well, for mosquitoes)—they don't suck blood, but rather live on plant nectar. I don't know what the full range of all Toxorhynchites species might be – our article lists at least forty or fifty species – but Toxorhynchites rajah comes from East Malaysia. This page has pictures of this mosquito in various stages of development. TenOfAllTrades(talk) 20:03, 6 December 2007 (UTC)

Ah—the Walter Reed Biosystems Unit indicates that the genus Toxorhynchites is very widespread: [5]. (There's also a great picture there—note the bent proboscis and long legs.) —Preceding unsigned comment added by TenOfAllTrades (talk • contribs) 20:12, 6 December 2007 (UTC)

Isn't the daddy long legs (UK edition) technically a mosquito? It's certainly fairly large for an insect and I know that some people are terrified of them. Makes a fairly loud (for an insect) thudding noise when it collides with windows and walls too. --Kurt Shaped Box (talk) 22:50, 6 December 2007 (UTC)

You can hear stag beetles flying towards you in the dusk before you can see them. I guess they would make a fair noise hitting glass. Lanfear's Bane | t 23:41, 6 December 2007 (UTC)

A friend of mine discovered that with the (very large) cockroaches in North Africa, much to his terror one night. English 'roaches just skitter around, you see... --Kurt Shaped Box (talk) 19:20, 7 December 2007 (UTC)

I don't think so. The article includes the phrase Unlike mosquitoes..., and lists mosquito eater as one of their alternative names. Skittle (talk) 00:21, 7 December 2007 (UTC)

Hmmm. Yes, you are correct. Same order, not the same family. Sorry about that. --Kurt Shaped Box (talk) 19:20, 7 December 2007 (UTC)

The so-called "Hexham Grey" seems to be in the running if we're talking about mozzies (Ozzies call them "mozzies", it seems) that bite people. --Milkbreath (talk) 20:03, 7 December 2007 (UTC)

worlds largest mosquitoes? Politicians.

Mammal lips

What is the purpose of the split in the top lips of many mammals? —Preceding unsigned comment added by 84.66.155.90 (talk) 20:46, 6 December 2007 (UTC)

There is cartilage there that allows muscles to have good control of the upper lip. It is called the philtrum. -- kainaw™ 21:26, 6 December 2007 (UTC)

Presumably it is so there is enough skin to stretch when you perform certain mouth movements? Like all the lines in your hand that just seem (to me at least) to be crease-lines because you don't always have your hands in such a way that maximises the amount of surface-area the skin needs to cover. I'm sure someone will confirm this is just gibberish if indeed it is. ny156uk (talk) 22:43, 6 December 2007 (UTC)

The heart

I was reading my bodybuilding magazine and I read that aerobic exercise strengthens the heart and makes the left ventricle thicker, I had previously thought that they said steroids was bad because steroids do that also, so is it really that bad? —Preceding unsigned comment added by 76.167.132.90 (talk) 23:56, 6 December 2007 (UTC)

We actually have a short article just on this (Left ventricular hypertrophy). Muscles naturally enlarge when they strengthen (see Muscle hypertrophy). Anabolic steroids, which are taken illicitly to this effect, are dangerous for their other influences on the human body (see Anabolic steroids#Adverse effects). Someguy1221 (talk) 00:18, 7 December 2007 (UTC)

Actually, I take that partially back. Our own articles disagree over whether LVH is a "bad thing." I'll be researching it now...Someguy1221 (talk) 00:30, 7 December 2007 (UTC)

Ok, I think I have it now. This paper shows that steroid-free exercise-induced LVH is accompanied by a clear increase in cardiac performance, one that is not seen in LVH caused by hypertension (the only alternate cause of LVH discussed in that article). Further, this paper indicates that LVH caused by steroid use is accompanied by decreases in certain aspects of cardiac performance. So LVH itself is not inherently good or bad, as our LVH article suggests, but the impact of LVH plus other, possibly unidentified changes in the heart, is very dependent on the cause of LVH. I hope this answers your question. Someguy1221 (talk) 00:44, 7 December 2007 (UTC)

One (somewhat comic) side-effect of exercise-induced LVH is that it causes you to have a different cardiac rhythm to normal people, which makes jittery paramedics fear something very nasty has happened to your heart. It's not unheard of for marathon runners (who encounter a paramedic for minor stuff like treating cuts and abrasions from a fall) to be whisked off to a cardiac care unit, while loudly protesting that they feel fine and really would rather carry on with the race. -- Finlay McWalter | Talk 01:01, 7 December 2007 (UTC)

I believe the 'nasty side effects' being referred to are hypertension, cardiovascular disease, coronary artery disease and the most horrific of all for our male counterparts, testicular atrophy, the latter of which you would usually not encounter in someone who had achieved left ventricular hypertrophy via aerobic exercise. Cyclonenim (talk) 00:23, 31 December 2007 (UTC)