From Wikipedia, the free encyclopedia

Science desk
< February 19	<< Jan | February | Mar >>	February 21 >

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.

Contents 1 February 20 1.1 what would you call a small mountain range 1.2 Does the human brain have limits? 1.3 Strange Picture 1.4 Spots 1.5 First robin in February? 1.6 Meerkats 1.7 Menstruation and lunar cycle 1.8 Electric Flux Units 1.9 Becoming a Spaceman 1.10 Science Fair (Quantum Dots)

[edit] February 20

[edit] what would you call a small mountain range

Like Potrero Hills specifically, this is regarding a dispute on the wording of navegation disambiguation tag at the top of the similarly named neighborhood Potrero Hill, San Francisco, California. It's sloppy to say for the potrero hills see potrero hills, but one user believes that it should not state, the minor mountain range see potero hills, because they don't count as a minor mountain range, so is there some other term which could be found mutually agreeable. hill range? minor range?Boomgaylove (talk) 04:39, 20 February 2008 (UTC)

Here's a topo map of the feature.—eric 05:25, 20 February 2008 (UTC)

scratch that, those Potrero Hills are about 30 miles away, southeast of Fairfield.—eric 06:14, 20 February 2008 (UTC)

You mean this? Certainly the word moutain does not spring to mind if that is where you are talking about. I would have thought range would be used to describe huge area. For the disambigution why not just say See Potrero Hills for East Bay Regional Park? David D. (Talk) 05:42, 20 February 2008 (UTC)

what east bay regional park??Boomgaylove (talk) 13:26, 20 February 2008 (UTC)

All parks in the East Bay are managed by the Easy Bat Regional Park district. I assume this one is too? I could be wrong. David D. (Talk) 17:20, 20 February 2008 (UTC)

Apparently its not one of their parks. http://www.ebparks.org/parks David D. (Talk) 17:38, 20 February 2008 (UTC)

I see the disambiguation at Potrero Hill, San Francisco, California currently reads For the Potrero Hills in Richmond, California, see Potrero Hills. What's wrong with that? David D. (Talk) 05:48, 20 February 2008 (UTC)

it's not a park at all dummy =PBoomgaylove (talk) 22:59, 21 February 2008 (UTC)

It's redundant, and the first part where it says potrero hills, in the {{Other|what it is|article title}} format is not within precedent or commom usage of that template.Boomgaylove (talk) 13:26, 20 February 2008 (UTC)

You don't have to use the template. David D. (Talk) 17:20, 20 February 2008 (UTC)

How about "bluffs"? —Preceding unsigned comment added by Boomgaylove (talk • contribs) 13:27, 20 February 2008 (UTC)

The're not bluffs, the're hills. David D. (Talk) 17:20, 20 February 2008 (UTC)

You're bluffing! (Sorry, it's in my contract). 206.252.74.48 (talk) 19:44, 20 February 2008 (UTC)

On a side note, what would you call an edit war over this and related topics? —Steve Summit (talk) 13:59, 20 February 2008 (UTC)

"Over the top"? "Over the hill and a long way off"? "Over here, over there...", "Mountains or molehills", "A summit, how high"? ; )) Julia Rossi (talk) 10:50, 21 February 2008 (UTC) Okay, I give up, it must be "a summit conference".

No, no, you're off in the wrong direction. A summit is an apex, an acme, a pinnacle, whereas that edit war was the absolute pits! —Steve Summit (talk) 04:33, 24 February 2008 (UTC)

In that case, a pit stop. That's in the building next door... Julia Rossi (talk) 08:25, 25 February 2008 (UTC)

[edit] Does the human brain have limits?

Does the human brain have "limits"? Is there only "so far" that it can go? For example, is it humanly possible, say, for a person to memorize an entire phone book? Or, are there some things just impossible / out of range for the human brain? Thanks. (Joseph A. Spadaro (talk) 07:11, 20 February 2008 (UTC))

Try photographic memory. This article led me to Ben Pridmore who holds the official world record for memorizing the order of a randomly shuffled 52-card deck in 26.28 seconds. Not exactly the phone book but pretty impressive. David D. (Talk) 07:23, 20 February 2008 (UTC)

Googling around a bit, this page seems to give an accurate scientific answer about this. The answer is not of course how much information is stored during a person's lifetime (ranges from hundreds of megabytes to many gigabytes), but how accurately he can recall that information. This is where a computer has a great advantage. Another interesting question is the difference between factual and visual information. As we know, computers need a great deal more storage for multimedia - so do the still and moving images that we keep in our brain also require more "storage space"? Even these blur over time, as the brain needs to refresh its pathways to older information, stored in a complex neural network of neurons (10 billion) and synapses (trillions or quadrillions). Sandman30s (talk) 15:12, 20 February 2008 (UTC)

Daniel Tammet memorized pi up to 22,514 digits in just over five hours. He also knows 11 languages and learned Icelandic in a week. -- MacAddct  1984 ^{(talk • contribs)} 15:10, 20 February 2008 (UTC)

According to something i heard on Paul Harvey's Rest ofthe story, the creator of Bingo (US) enlisted the help of a math whiz who manually came up with thousands of cards with all the different permutations, but wound up going insane because of it; so, that might be a good place to startr as far as a "limit." Sorry, I don't remember the name. (That, of course, was the days before computers.)209.244.30.221 (talk) 15:47, 20 February 2008 (UTC)

The brain is a physical device, so it certainly has limits. You might find Seth Lloyd's famous paper Ultimate physical limits to computation to be informative on the upper limits of the brain's capacities even if it was optimally configured for data storage (which it certainly isn't, as all my lost pens will attest). --Sean 18:09, 20 February 2008 (UTC)

No, there are no limits to the human brain. You can do anything if you put your mind to it. 64.236.121.129 (talk) 19:48, 20 February 2008 (UTC)

I do wish that was true, but so far I haven't managed to bend a single spoon using just thought. All my attempts at unaided flight have failed as well. 206.252.74.48 (talk) 20:50, 20 February 2008 (UTC)

Tell that to Deep Blue. APL (talk) 21:08, 20 February 2008 (UTC)

It's possible for a human to do anything that's physically possible; but not all humans can do all physically possible things. A person without legs cannot walk (defined as the action of moving by the use of legs), but people with legs can. A person born without eyes cannot see, but people with eyes can. The question is, what is the limit of physical possibility. Before Roger Bannister, it was considered very unlikely that a human could run a mile in 4 minutes. Now, that's considered a pretty ordinary achievement among athletes. But can a human run a mile in 2 minutes? Most would say no. But you never know. -- JackofOz (talk) 21:52, 20 February 2008 (UTC)

Jack, you finish there with the understatement of the year. Does anyone think a 2min mile is possible? The 100m WR is currently 9.74 s. Assumingly Asafa Powell could keep going that would equate to a 2min 36.8. The 200m WR is 19.32 s. Assuming Michael Johnson could keep going that would equate to a 2min 35.5. So even a relay of the best sprinters in the world could not beat 2 min. In this case I think it safe to say that Homo sapiens will never break 2 minutes for the mile. :) David D. (Talk) 22:04, 20 February 2008 (UTC)

Ah, but what kind of assumptions are you making? Surely it would be possible to run a 2-minute mile on a planet with a different gravity? Mars, perhaps, or the Moon.--Eriastrum (talk) 22:25, 20 February 2008 (UTC)

I would imagine you'd run a bit slower if the gravity is too low, as you'd end up putting too much of your energy into go up and not forward. Also, you'd need to have some sort of contained atmosphere, as doing a 2 minute mile in a bulky space suit might be tricky. -- MacAddct  1984 ^{(talk • contribs)} 22:37, 20 February 2008 (UTC)

I have a better idea - redefine the mile. Chris16447 (talk) 23:31, 20 February 2008 (UTC)

If you're only talking about their being a limit, I can tell you that a 0.00000537 second mile is impossible. It's slightly faster than the speed of light. The OP was talking about you're mind, so using 10⁵⁰ bits/s/kg from Sentience Quotient, and a mass of 3*10⁵² kg from Orders of magnitude (mass), I can tell you that you can't process more than 3*10¹⁰³ (3,000 googols) bits per second. — Daniel 23:33, 20 February 2008 (UTC)

Apparently, the human brain has no limits as to the amount of conceit, anthropocentrism, and human exceptionalism it is capable of. MrRedact (talk) 02:11, 21 February 2008 (UTC)

Is it too late to ask if a 2min mile's possible if the athletes were running on a downhill slope with a tail wind? I mean do we have to stick to track conditions in this hypothetical?Julia Rossi (talk) 10:56, 21 February 2008 (UTC)

Well in that case we might as well define it as freefall. How fast can a sky diver dive a mile? But I'm not sure that is relevant to the original allusion to Bannisters impossible feat. David D. (Talk) 18:44, 21 February 2008 (UTC)

Thanks. Good discussion. But ... uhhhh ... can a person memorize a phone book or not? (Joseph A. Spadaro (talk) 14:45, 21 February 2008 (UTC))

Well, the point of a lot of this discussion was to emphasize that it's very hard (if not impossible) to give a clear "no" answer. In the absence of a confirmed "yes", all that's left is "maybe". Has anybody done it? No. But could they? Maybe. — Lomn 16:22, 21 February 2008 (UTC)

That depends on how big the phone book in question is. My old (1990) Guinness Book of World Records lists Gou Lan-ying of China as having memorized over 15,000 phone numbers. Tom Morton has memorized over 16,000 phone numbers. Akira Haraguchi holds the record for memorizing pi, at 100,000 digits, which is the number of digits in about 14,285 7-digit phone numbers. There do exist phone books for small towns with fewer phone numbers than that. But can a human memorize the 180,000,000 phone numbers listed on whitepages.com? No way. MrRedact (talk) 18:46, 21 February 2008 (UTC)

Thanks for all the input. Very interesting. Thanks ... much appreciated ... (Joseph A. Spadaro (talk) 01:10, 24 February 2008 (UTC))

Now, can a person remember a 100+ letter-long word? Absolutely, I've done it. A 1000+ letter-long word? Probably, if someone can remember a hundred thousand numbers, which are probably harder to remember than letters, but I have trouble going through the word once, let alone practice it. How about a 100 000+ letter-long word? Perhaps, but reciting it would take several hours. I've also heard that it's impossible to phisicly forget a piece of information that was at one point memorised as major data, and maybe forgetting is because of a mental block or a "wrong answer" that prevents access to the real one, but I'm not sure if that's true for all memories, especially as people age and they get corroded. It's also possible to remember parts your early infancy, if you haven't forgotten it already or it has been corroded by so much "false data" that it's effectively useless. Now keep in mind that it's easier to hack a computer or put a virus into it than with a brain that didn't have this disorder in the first place. Hope this helps. Thanks. ~AH1^(TCU) 01:41, 26 February 2008 (UTC)

[edit] Strange Picture

Look at this picture of the A380. http://i.l.cnn.net/cnn/2008/BUSINESS/02/20/airbus.ap/art.airbus.afp.gi.jpg

The right wing looks short but the left wing looks very long. Has this picture been delibrately modified? Is it a real picture? 122.107.226.136 (talk) 12:54, 20 February 2008 (UTC)

I agree it looks odd, but I think it's a real picture. Since the near wing is pointed towards the camera, it is foreshortened. Since the far wing is perpendicular to the camera, its full length is emphasized.

Part of the surprise is just due to how very far the wings on modern planes are swept back -- they don't stick straight out from the fuselage by any stretch of the imagination. —Steve Summit (talk) 13:34, 20 February 2008 (UTC)

Also, since we're kind of viewing the plane from above, consider that dihedral is also contributing to the close wing's foreshortening. jeffjon (talk) 13:37, 20 February 2008 (UTC)

It is probably related to this illusion, where the image gets flattened when taking photos with a zoom lens. -- MacAddct  1984 ^{(talk • contribs)} 15:05, 20 February 2008 (UTC)

Do you think so? I wouldn't have said that had anything to do with it. The issue here isn't that depth is compressed, it's that the wings are at different angles to the viewer and so they look like they have different lengths. At best, I'd say that we're used to the closer wing looking bigger from our personal up-close experience, so when we see a long-lens shot, we subconsciously compensate a bit in the opposite direction. I'd think that's pretty minor, though; I'd think most people see as many photos of planes as they see real up-close planes. jeffjon (talk) 15:46, 20 February 2008 (UTC)

Are the A380's wings actually horizontal? If they slope up from the fuselage, this could explain it a bit. -mattbuck (Talk) 10:20, 21 February 2008 (UTC)

They do slope up, as seen here, though not as much as some other types of planes. Check out the definition ofdihedral. jeffjon (talk) 13:41, 21 February 2008 (UTC)

Looks photoshopped.. what could possibly be going on in that picture? If the back plane is way farther back then wouldn't it be the smaller one? :D\=< (talk) 23:45, 22 February 2008 (UTC)

That A380 is ginormous. I just want to point that out to anyone who doesn't notice. 64.236.121.129 (talk) 19:48, 20 February 2008 (UTC)

This is quite an interesting exercise. If I'd been shown the photo for 10 seconds, without any commentary, and then asked to draw it as accurately as I could from memory, I'd have made the wings roughly equal in size. My brain instantly recognised that the a/c was banking, and compensated for the apparent difference in the length of the wings. To me, there was nothing "odd" about it; the wings were of equal length, obviously. It was only when I looked at it closely that I realised the left wing in the image is actually almost twice as long as the right. I failed to distinguish between the image of the a/c, and the a/c itself (based on my prior knowledge of the symmetrical shape of a/c). Teaching people how to reproduce what they actually see and not what their left-brain logic tells them "must be there" is covered in various places, such as Betty Edwards's Drawing on the Right Side of the Brain. This left wing-right wing photo is an excellent metaphor for that whole area of study, so thank you, 122.107.226.136. -- JackofOz (talk) 21:36, 20 February 2008 (UTC)

[edit] Spots

Request for diagnosis removed. The identification of a medical condition is the textbook definition of "diagnosis", and saying "I'm not asking for a diagnosis" does not change this. Follow up with your doctor if concerned. — Lomn 16:09, 20 February 2008 (UTC)

[edit] First robin in February?

Okay, my mom's in NE Ohio, and she swears that a few days ago, she saw a robin at the bird bath. Is it really normal for them to be up here this early, and if so, why is there the thing about them being the first sign of spring - it is not springlike here. I could understand if it were, say, 65 Fahrenheit and had been in the 50s a few days in a row; then animals can be fooled.209.244.30.221 (talk) 15:56, 20 February 2008 (UTC)

It happens. There's a map here that shows robins in February in the USA. Some even overwinter; I've seen them deep in the Pine Barrens in January. See these folks for everything robin. --Milkbreath (talk) 16:16, 20 February 2008 (UTC)

Last weekend was the Great Backyard Bird Count, and I had robins and bluebirds (unusually early) in southwestern PA. I know they were also reported on a lot of lists in Pittsburgh. You can pull up results for her area at the GBBC website, to see if others reported robins—this year, it wouldn't surprise me. You can also try eBird to get annual charts of birds' comings and goings for a particular area. -- Coneslayer (talk) 16:21, 20 February 2008 (UTC)

I saw lots in January here in Colorado, but I think they stay all winter, since it warms back up pretty regularly. Seems to be supported by our range map, which also shows Ohio in the year round range. — Laura Scudder ☎ 22:28, 20 February 2008 (UTC)

As to your second question, I think it's robins singing, not just being spotted, that is supposed to be a sign of spring. — Laura Scudder ☎ 22:35, 20 February 2008 (UTC)

I feel I should point out that range maps like the one here are pretty coarse, and the range will vary over time and from year to year. Also, not every single area within the green will hold a robin year-round; there are micro-climates and the like that limit their ability to overwinter. You can imagine the green breaking up and going patchy as it approaches the yellow. --Milkbreath (talk) 10:27, 21 February 2008 (UTC)

[edit] Meerkats

I can't find any thing that will tell me when Meerkats where first discovered here on Earth, can someone please help. Thanks, Megan —Preceding unsigned comment added by 69.133.3.155 (talk) 19:15, 20 February 2008 (UTC)

It depends on what you mean by "discovered". If you mean by humans, then the answer would be a million or so years ago when Homo sapiens first evolved in Africa, where the meerkat is native. If you mean in a formal scientific sense, then it was in 1776 when the species Suricata suricatta was first described by Johann Christian Daniel von Schreber.--Eriastrum (talk) 19:49, 20 February 2008 (UTC)

I believe they have yet to be discovered on planets other than Earth, but I could be wrong. Gwinva (talk) 00:34, 21 February 2008 (UTC)

[edit] Menstruation and lunar cycle

Is there any scientific theory - no matter how offbeat - explaining why the lunar cycle and human menstruation cycle are approximately the same length? Or is it just complete coincidence? TheMathemagician (talk) —Preceding comment was added at 19:39, 20 February 2008 (UTC)

yep, it's pretty much coincidence. - Nunh-huh 19:56, 20 February 2008 (UTC)

The whole thing is controversial, but see our articles menstrual cycle and culture and menstruation.--Eriastrum (talk) 20:06, 20 February 2008 (UTC)

(ec) I think this is a good paper on the idea. If you search google, you'll find the idea of a link between lunar and menstrual cycle to be a common one (and has quite a few papers published on it). According to the article I linked to, there is no statistically significant evidence of a link between the lunar and menstrual cycles. Although a number of much earlier papers argued otherwise, the linked paper suggests those previous studies suffered from problematic sampling. The paper also argues that claimed evidence of a similar concept, that women who live together will have similar menstrual cycles, suffered from a flawed statistical analysis. Someguy1221 (talk) 20:13, 20 February 2008 (UTC)

Wait a minute. There are two different questions here. As someguy points out the idea that the menstrual cycle coincides with the lunar cycle is bogus. However, the original poster just asked about the length of the menstral cycle being about the same length as a lunar cycle (28 days). The length of the menstral cycle might (remote possibility here) have evolved originally under the influence of the lunar cycle. After all a number of marine organisms are linked to the tidal (lunar) cycles.--Eriastrum (talk) 20:32, 20 February 2008 (UTC)

Actually, women in non-western countries tend to have longer cycles - 4 months long for some I think. It's a coincidence nothing more. Heck, western cycles aren't often 28 days - they're roughly that, but often longer. -mattbuck (Talk) 21:06, 20 February 2008 (UTC)

While 28 days is commonly given as the average length, the normal range is 21-35 days, so it is hard to confirm any link with a lunar cycle. Gwinva (talk) 00:41, 21 February 2008 (UTC)

Mattbuck, do you have a reference for the 4 month thing (as in, a population where that's normal)? That seems implausible to me. --Allen (talk) 04:35, 21 February 2008 (UTC)

He almost certainly meant 4 weeks long. —Preceding unsigned comment added by 79.122.42.134 (talk) 10:04, 21 February 2008 (UTC)

"4 months long for some" may mean "for some women" rather than "for some countries." I mean, I can't read Matt's mind, but that would certainly be possible. Someguy1221 (talk) 10:13, 21 February 2008 (UTC)

Nope, I meant 4 months. It was in New Scientist a month or two ago. -mattbuck (Talk) 10:19, 21 February 2008 (UTC)

Were you by chance referring to this article on artificially lengthening the menstrual cycle? I didn't see anything else remotely relevant in the more recent issues. Someguy1221 (talk) 22:41, 21 February 2008 (UTC)

That sounds about right. Maybe I'm wrong, who knows, it was a while ago. -mattbuck (Talk) 09:44, 22 February 2008 (UTC)

Four months is certainly not a normal menstrual cycle. Amennorhea is defined as "three months without a period in a woman with a history of regular cyclic bleeding, or six months in a woman with a history of irregular periods." Almost certainly you were thinking of the new techniques of artificially prolonging the duration between periods of menstrual bleeding. - Nunh-huh 16:13, 22 February 2008 (UTC)

[edit] Electric Flux Units

Electric Flux is measured is Nm² /C. If a Netwon-meter is a joule and a joule/coulomb is a volt, can it be stated that flux is measured in volt-meters? If not, why? 21:15, 20 February 2008 (UTC)

It can. Electric field can be measured in volts/meter, and flux is field times area, so you get units of (V/m)(m²)=Vm. --mglg_(talk) 21:40, 20 February 2008 (UTC)

[edit] Becoming a Spaceman

How does one become a spaceman? What kind of training/education is required? 64.236.121.129 (talk) 21:46, 20 February 2008 (UTC)

See [1]

Make a good chunk of money, wait a few years, then book your flight. Clarityfiend (talk) 22:12, 20 February 2008 (UTC)

NASA are hiring. Angus Lepper^{(T, C, D)} 22:47, 20 February 2008 (UTC)

Hehehehhe "Frequent travel may be a requirement"... Can I catch the bus? Shniken1 (talk) 05:07, 21 February 2008 (UTC)

Actually, I think they have to do an awful lot of public relations travel. A NASA astronaut who never gets gets to fly on a mission may still have to do many school visits, ect. I know this only because my workplace has been trying to arrange for an astronaut as a guest speaker for several years. ike9898 (talk) 15:05, 21 February 2008 (UTC)

Also, an astronaut training for the International Space Station will train in Houston, Florida, Canada, Russia, Germany and Japan, at the very least. anonymous6494 04:14, 22 February 2008 (UTC)

[edit] Science Fair (Quantum Dots)

I am in the science fair this year and am at a complete loss as to what to put in my "future" section. (A future section tells real-life applications for the experiment you performed.) I did an experiment in which I had to find the wavelength of 4 samples of indium phosphide quantum dots when shown a λ=405nm LED. Then, I had a formula in which I used the wavelength of the light fluoresced by the quantum dot sample to relate the wavelength of fluoresence to the radius of the quantum dot. As I said, I am at a complete loss as to how to apply this (relating the radius and wavelength) in a real-life application. I asked the chemistry teachers at school and they can't think of one either. Any suggestions are greatly appreciated. Thanks, Zrs 12 (talk) 22:47, 20 February 2008 (UTC)

Many food substances are colloids, for example milk has droplets of fat in them. In Homogenised milk the droplets are made to be in a certain range of sizes. If they are too big you will get cream rising to the top of the milk. The size of these droplets can be investigated via light scattering.. Many other products use the same theory..

Not really a future application as it is already happening. Shniken1 (talk) 01:54, 21 February 2008 (UTC)

It doesn't have to be a future application. Just any application past, present, or future. I, personally, haven't a clue as to why the choose to call it "future". I think it's because you also must put things in that section which could be done to improve the experiment (in the future if you did it again). Thank you for your suggestion :-); much appreciated. -- Zrs 12 (talk) 02:04, 21 February 2008 (UTC)

I hear Dippin' Dots are the ice cream of the future. -- MacAddct  1984 ^{(talk • contribs)} 02:53, 21 February 2008 (UTC)

....Ok? Zrs 12 (talk) 14:32, 21 February 2008 (UTC)

He was just trying to be funny (and succeeded, in my opinion). However, I will not call any ice cream the "ice cream of the future" until it is unmeltable, never sticky, and tastes exactly like whatever you want it to taste like. 206.252.74.48 (talk) 18:21, 21 February 2008 (UTC)

I think eating whatever you want it to be may be the better option here. Why eat bacon-flavoured ice-cream when you can eat bacon itself? It also doesn't melt, isn't sticky (well mostly), and tastes exactly like bacon. --antilived^{T | C | G} 03:30, 22 February 2008 (UTC)

Yes. I know he was trying to be funny but that didn't pertain to what was being discussed. It just seemed random to me. Zrs 12 (talk) 23:14, 21 February 2008 (UTC)

Hi. What's wrong with bacon-flavoured ice cream? Seriously. One time I got in trouble for suggesting tomato-and-egg flavoured ice cream. Seriously, how could they know that it doesn't go together, if they've tasted both but not at the same time? It depends on what the person usually eats. I'd rather prefer tomato and egg at the same time in a sandwich. Or how about an oreo ice cream? If it doesn't melt how can you keep it cold? Or honey-sausage-lettuce-mint-strawberry-hay-butter-mozerella-earwax-flavoured ice cream? Ok so it got vomitrocious when I added the hay and earwax, huh? I heard there are earwax and soap-flavored jelly beans. Thanks. ~AH1^(TCU) 01:21, 26 February 2008 (UTC)