Wikipedia:Reference desk/Archives/Science/2008 May 12

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May 12

Guinea Pig head bump

I have two guinea pigs, and when i gently place my hand on either's noses, They quickly thrust their heads up. Why is this? Gbgg89 (talk) 04:29, 12 May 2008 (UTC)

Maybe it is a response to a nearby source of food, so perhaps to bite your finger? Astronaut (talk) 09:29, 12 May 2008 (UTC)

Guinea pigs are herbivores, so that's unlikely. Given that noses are very sensitive organs in most species, my money is on it being a protective reaction. Since guinea pigs are also social animals, a submissiveness reaction may also be possible. 71.236.23.111 (talk) 16:33, 14 May 2008 (UTC)

Maps and Time lines of plants, insects, sm. animals, and terrain.

I am looking to assemble a wide verity of information grouped together covering a certain area of land.

Along the border of China and Mongolia. 100 miles south of border to north 200 miles inside Mongolia From western border to eastern border

All from the time of 125 million to 300 million years ago.

Maps and graphs containing:

-Topographical : - Terrain

                - Water levels highs and lows
                - Some research sight (containing programs as to what the place looked like
                  back then

-Time lines of : - insects (paleontology)

                - sm. animals
                - fossils
                - charts graphs

WHY:

First Flower PBS Airdate: April 17, 2007 Professor Sun Ge, from China's Jilin University, is certain that early flowers evolved here, in northern China, and he is determined to find the world's first.

Not far from the border of Inner Mongolia, there is a remarkable fossil site that is revealing what the Earth looked like more than 100,000,000 years ago. —Preceding unsigned comment added by Coffee1030 (talk • contribs) 05:15, 12 May 2008 (UTC)

ARUN SINGH BAGH

WHAT IS THE NAME OF THE WOODEN BLOCK ON WHICH THE WINNERS IN OLYMPICS STAND WHEN THEY GET FIRST SECOND AND THIRD POSITION —Preceding unsigned comment added by 195.189.142.54 (talk) 06:03, 12 May 2008 (UTC)

It is called a medal podium. Rockpocket 06:12, 12 May 2008 (UTC)

telecommunication-microwave survey as used in network establishment

elecommunication-microwave survey as used in network establishment — Preceding unsigned comment added by 61.246.1.108 (talk) 07:30, 12 May 2008

Do you have a question? Astronaut (talk) 09:07, 12 May 2008 (UTC)

It could be a site survey. Graeme Bartlett (talk) 04:55, 13 May 2008 (UTC)

Insanity

I don't know a lot about psychology (I got as far as AP psych in high school, so I know the basics), but I've recently gotten curious about how people go crazy. Since I don't have much background in the area, I don't where to go to learn about it. Any ideas? Also, as a subquestion, does insanity universally degrade a person's ability to succeed, or are there cases of people who become smarter, more creative, what-have-you after losing it than they were before? Black Carrot (talk) 07:35, 12 May 2008 (UTC)

The answer will depend on which specific conditions you group under the umbrella term of insanity - note that "insanity" is no longer considered a medical diagnosis (although it is still a rather loosely defined legal term in the UK and the USA). A fairly generic answer to your various questions might be as follows:

1. Many psychiatric conditions may be diagnosed in childhood, in adolesence, or appear in later life, possibly due to an event that triggers or exacerbates a previously unnoticed condition.
2. There are several autobographical and semi-autobiographical accounts of the onset of a psychiatric condition - see Girl, Interrupted, I Never Promised You a Rose Garden, The Bell Jar.
3. Most psychiatric conditions, as long as they are properly diagnosed and managed, do not prevent a person living a "normal" and indeed successful life. There are several well-known examples of people with a psychiatric condition that appears to be intimately linked to their success in a particular field - see, for example, John Forbes Nash (schizophrenia); Vincent van Gogh (possibly schizophrenia or bipolar disorder); Stephen Fry (bipolar disorder); Richard Borcherds (Asperger syndrome) ... Gandalf61 (talk) 10:25, 12 May 2008 (UTC)

Try reading up on: biopsychiatry and causes of mental disorders. Re Gandalf61, see creativity and mental illness. --Mark PEA (talk) 20:00, 12 May 2008 (UTC)

Entropy and Creationism

A common argument for Creationism is that as entropy can only increase there must be a start where everything is in order, which is when God created the universe. What is a rebuttal for this argument? How come entropy was so low after the Big Bang? --antilived^{T | C | G} 07:38, 12 May 2008 (UTC)

See Objections_to_evolution#Evolution_violates_the_second_law_of_thermodynamics, Entropy and life and Five Major Misconceptions about Evolution at TalkOrigins. Guettarda (talk) 07:53, 12 May 2008 (UTC)

OK that makes sense but how come the universe didn't go into heat death as soon as it was created? What had caused the disequilibrium (if that's a word)? --antilived^{T | C | G} 08:10, 12 May 2008 (UTC)

"Why was the entropy of the early universe so low ?" is a good question, and one of the big puzzles of cosmology. Rogare Penrose addresses the question at some length in The Road to Reality. There are several candidate explanations:

1. The universe has a very, very long pre-Big Bang history, and what we think of and observe as the Big Bang was a random fluctuation in which all the matter of the universe happened to arrange itself into an especially low entropy state (remember that processes that reduce entropy are not absolutely impossible, they are just very unlikely, and anything that is not impossible can happen if you wait long enough). In this view, our current state of increasing entropy is a relativley short-lived phase in the mega-history of the universe.
2. A large number of universes are continually being created, possibly by some sort of quantum "budding" process. Those that start in high entropy states are spectactuarly dull places and do not give rise to life. Only a universe that starts in a low entropy state could eventually give rise to beings that ask the question "why was the entropy of the early universe so low ?". This is a version of the strong anthropic principle.
3. Some mechanism active only in the early universe, and possibly connected with cosmic inflation, drove the universe into a low entropy state. Such a mechanism would break the second law of thermodynamics, so it cannot be active in the universe as we observe it today.

So there are various possible explanations - we just don't yet know which one is correct. Gandalf61 (talk) 09:25, 12 May 2008 (UTC)

And note that even if you want to say that God had a hand in this, it still requires an understanding of what naturalistic process God would have used to do it. "God did it" doesn't relieve the need for a physical explanation—even if it was done by some sort of intelligent deity there still would be a corresponding physical expression of that action. --98.217.8.46 (talk) 15:02, 12 May 2008 (UTC)

The first two options don't work at all, and Penrose should realize this. They're the cosmological equivalent of the 747-from-a-junkyard argument against biological evolution. Darwinian evolution is not a 747-from-a-junkyard theory, and if it were then it would be as useless as the ID people think it is. It would be unfalsifiable and predict nothing. Option 3 isn't an option, it's practically a definition of what it means to explain something. Explaining something doesn't mean showing that the world can be that way, it means showing that it couldn't have been some other way. You have to produce a mechanism that makes the world we see more likely than it appears on the surface. You have to rule out something beyond what you ruled out a priori with your anthropic (or aeronautic) principle.

In principle the idea of anthropic reasoning makes sense. What scientists do is reason from the available evidence to a theoretical model that explains it. One piece of evidence available to us is the existence of homo sapiens. If you reason from that evidence to a theoretical conclusion, you've engaged in anthropic reasoning. But in practice no one ever succeeds in doing that; it's too hard. Progress in natural philosophy began when people started to gather evidence about much simpler things, like the motion of a wheel on an inclined plane. As far as I know there has never been a successful anthropic argument in the history of science. All of its claimed successes are co-opted. Fred Hoyle reasoned from the observed abundance of carbon in the universe to a prediction that carbon must have a particular energy level, which was later found. This was claimed as an anthropic prediction. Why? Because human beings contain lots of carbon. It could just as well have been lithium instead of carbon that went into his argument, and then no one would have called it anthropic. Even worse is the current claims of anthropic reasoning in string theory. They want to narrow down the possible flux compactifications in string theory by requiring that they produce a universe consistent with the one we see. This is known as "fitting the model to the data", and it's what scientists have always done. The data is this case is that which supports the Standard Model and the existence of a small positive cosmological constant. It seriously scares me that prominent string theorists think they're "reasoning anthropically" when they do this. That, more than anything else, makes me worry that they've completely lost sight of reality. -- BenRG (talk) 16:56, 12 May 2008 (UTC)

Not going to pretend that I understand what triggered that particular rant, but let's clarify something for the record. Penrose doesn't actually come down in favour of any of the above three explanations. In fact, he sets them up in order to knock them down in favour of his own explanation, which is connected with quantum gravity. Gandalf61 (talk) 21:55, 12 May 2008 (UTC)

The argument that "some supernatural entity must have started the universe in perfect order" is hardly an argument for big-"C" Creationism, since that entity could have been anything. --Sean 13:08, 15 May 2008 (UTC)

Oh - this is a classic numbskull creationist argument. You have to be careful with the OP's statement about entropy. It is NOT true to say that "entropy can only increase". You missed the first half of the second law of thermodynamics. The correct way to simply state this is: "Within a closed system entropy can only increase." (To quote entropy: Spontaneous changes, in isolated systems, occur with an increase in entropy.) So if we consider the Earth to be a closed system (which it's not - but we'll quietly pretend that it is) - then evolution can create localised pockets of decreasing entropy at the cost of increasing entropy much more steeply elsewhere on the planet. Thermodynamics allows this. For example, take 20 dice in a cup. You can go and painstakingly take each one from the cup, turn itto show a 6 and line them up into a nice neat row. The entropy of the dice decreased - they are now much less random. But it took energy to make that happen. In using your hands to straighten them up - you consumed a few more calories and you might maybe eat a little more as a result. Just toss 20 nicely ordered dice onto the table without going to a lot of effort - and guess what? Entropy kicks in and they're all disordered again. Entropy only decreased when you put energy into the system from outside. Taking nice well-ordered food energy and turning it into disorderly end products increased the entropy of our world by considerably more than straightening up the dice did. Humans are going around forcing local pockets of entropy to reduce all the time by activities such as collecting up scattered amounts of iron ore and making cars out of them...but in the process, we are consuming energy and creating lots of ugly chaos elsewhere in the process. So when animals evolved, their LOCAL entropy went down - but the entropy of the planet went up by more than enough to compensate for that. Entropy LOCALLY decreases in all sorts of natural situations - the growth of crystals in a liquid solution for example. It's only within a closed system that entropy increases. You can't use a misstatement of a law of physics to prove or disprove anything! 66.137.234.217 (talk) 15:12, 17 May 2008 (UTC)

Michelson Interferometer

If the mirror is moved away then the number of fringes appearing in the microscope would change or not? If so then it is because the length of path is changing and so fringes are closely spaced. —Preceding unsigned comment added by MAQMAQ (talk • contribs) 08:54, 12 May 2008 (UTC)

Please do your own homework.

Welcome to the Reference Desk. Your question appears to be a homework question. I apologize if this is a misevaluation, but it is our policy here to not do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn how to solve such problems. But here is a hint to help you: consider what the interferometer is doing, how the fringes are created and what happens if one of the mirrors is moved.

Please attempt to solve the problem yourself first. The Michelson interferometer article might help, or you can search Wikipedia or search the Web.

Astronaut (talk) 09:27, 12 May 2008 (UTC)

Aloe Vera

I have been told that Aloe Vera Gelly will kill ear mites in dogs. Can anyone confirm this? Mr Beans Backside (talk) 10:12, 12 May 2008 (UTC)

Please ask your veterinarian. -- Coneslayer (talk) 11:47, 12 May 2008 (UTC)

Petroleum jelly and mineral oil are sometimes used to kill parasites on animals - mainly through suffocation. However, proper application can be tricky, and severe infestations may require additional medical help. Phoning your veterinarian's office is highly recommended - depending on your particular situation, they may be able to help you over the phone, without necessitating an office visit. -- 128.104.112.147 (talk) 22:27, 13 May 2008 (UTC)

Plants

When do plants use the cyclic electron pathway instead of the noncyclic pathway? Mr Beans Backside (talk) 10:13, 12 May 2008 (UTC)

You mean, "why do plants use the non-cyclic pathway?" The cyclic pathway has as its sole useful product ATP, whereas the non-cyclic pathway also produces NADPH (in addition to oxygen), which is necessary for driving the calvin cycle. Indeed, the cyclic pathway is considered more primitive; any photosynthetic organism relying solely on that process would have a fine source of ATP only in the daylight, and would need yet another process for using that energy to obtain or build the various molecules it needs. An organism using the non-cyclic pathway can use the NADPH to drive the conversion of CO2 into sugars, which can be used as stable stores of energy, polymerized into structural molecules, or converted into virtually any other molecule the plant needs. Someguy1221 (talk) 15:24, 12 May 2008 (UTC)

Global warming

What are some simple steps or creative ideas that people can take at home and work to combat global warming? Mr Beans Backside (talk) 11:50, 12 May 2008 (UTC)

• Ditch your SUV for something that uses less than 6 litres of petrol per 100km
• Plant a tree
• Turn down the temperature on your geyser or get a blanket to insulate it (in SA we use electrically powered geysers and our electricity is generated from coal (mostly) so this may not apply to you) and don't waste energy
• Make sure your house is well insulated
• Vote for politicians who are committed to reducing CO2 levels
• Recycle

I see there are quite a few wiki articles but linking all of them will make you less inclined to read any of them so I'll wait for someone to link the best one.

Zain Ebrahim (talk) 12:49, 12 May 2008 (UTC)

For those not familiar with British idiom, a geyser in this context is a water heater, and not an erupting hot spring. TenOfAllTrades(talk) 13:52, 12 May 2008 (UTC)

Is it some dialect? I'm British (North-West) and did not recognise the term, though I did surmise the correct meaning. --Seans Potato Business 14:14, 12 May 2008 (UTC)

I'm British, South-East, and didn't recognise it either. Zain mentions SA (South Africa, presumably) - I guess it's a term local to there. --Tango (talk) 14:18, 12 May 2008 (UTC)

Oh Sorry! I've only ever referred to it as a geyser and assumed it was a universal term. It not only heats the water but it also stores the heated water. Does a water heater do that as well or do you guys store the water elsewhere? Zain Ebrahim (talk) 14:42, 12 May 2008 (UTC)

Modern systems heat the water as its needed. You switch on the tap and the heater (or "boiler") switches on and hot water comes from the tap. This system is more energy-efficient than trying to store a quantity of hot water. Such storage systems do exist in the UK but are comparatively rare in low-usage applications (average household). ----Seans Potato Business 15:16, 12 May 2008 (UTC)

Interesting. Thanks. Zain Ebrahim (talk) 16:10, 12 May 2008 (UTC)

In the United States, the systems that Seans Potato Business described are uncommon. The common heater is the kind with a storage tank, like you described. However, the term "geyser" was completely unfamiliar to me. We just call them "water heaters" (or, rather strangely, "hot water heaters"). -- Coneslayer (talk) 16:32, 12 May 2008 (UTC)

Interestingly enough, the disambiguation page for "geyser" says that is can be "A water heating system, in British English". Although I have lived in the USA all my life, as a self-described Anglophile I understood geyser as used by Zain, so I'm perplexed by our NW and SE British colleagues indicating non-awareness of the term. Perhaps you need to read more Agatha Christie ;-) The various types of heaters and some of the terminology are discussed in the article water heating. --LarryMac | Talk 17:14, 12 May 2008 (UTC)

Geyser is also the Dutch word for an old-fashioned water heater (nowadays 'everyone' uses boilers). I wonder if this has anything to do with Afrikaans stemming from Dutch. DirkvdM (talk) 08:34, 14 May 2008 (UTC)

What I know as geysers used to be fairly common in the UK in my younger days - at least up to the 1970s. They were gas-powered devices where the main gas burner would ignite from a pilot light, usually with a terrifying whoomph, when the water was turned on. There was great skill required in getting the rate of water-flow just right: too fast and it wouldn't get hot enough, too slow and the gas would go out. AndrewWTaylor (talk) 19:58, 12 May 2008 (UTC)

I know these things as "boilers". In my experience, the hot water is usually stored in the UK. You have a boiler and a hot water tank. Heating the water immeadiately before using it sounds hard, since you need to heat it really quickly (certainly more efficient, though). --Tango (talk) 10:58, 13 May 2008 (UTC)

That kind is called a demand or on-demand or tankless water heater. --Anon, 22:22 UTC, May 13, 2008.

Eat less meat or go vegetarian. 200.127.59.151 (talk) 15:54, 12 May 2008 (UTC)

He was talking about lowering global temperature, how does eating less meat contribute? Mac Davis (talk) 17:55, 12 May 2008 (UTC)

200 was probably referring to Attribution of recent climate change#Key attributions#Land use#Livestock and land use. Zain Ebrahim (talk) 18:14, 12 May 2008 (UTC)

(edit conflict) In theory, less people eating meat would mean less land used for grazing lands. Less rain forests clear-cut to create grazing lands leaves more trees. More trees consume more carbon dioxide. And so on. Of course there's all that methane not being produced by farting cattle as well. --LarryMac | Talk 18:18, 12 May 2008 (UTC)

It's not in the farts, the cows breathe out (most of) the methane. DirkvdM (talk) 08:34, 14 May 2008 (UTC)

Change your incandescent lightbulbs to compact fluorescent lamps.118.90.102.125 (talk) 12:38, 13 May 2008 (UTC)

As it is scientifically proven that humans emit carbon dioxide, the best way to reduce CO2 emissions is to engage in genocide of the human race.--WaltCip (talk) 12:59, 13 May 2008 (UTC)

Nope, Humans themselves are carbon neutral. All the CO2 you emit ultimately comes from plants who sucked it out of the atmosphere. Some serious suggestions are:

• Walk short distances and use a bicycle for medium ones. Also good for your health.
• Use less air conditioning (and lobby for reasonable settings in public buildings). If it's 35 degrees Celsius outside, its nonsense to cool a building to 20. People adequately dressed for outdoors will catch a cold...
• Preferably buy food that is in season, and from local suppliers if possible.
• Stop whining about high gas prices. Indeed, lobby for a tax system that taxes products roughly proportional to environmental impact. This motivates people to invest in energy-saving devices.
• Buy electricity from renewable sources, if available. In this case the market impact is probably more in the signal than in the direct effect (many electricity companies split their existing mix and sell the clean part at a higher price, and the remaining worse mix to people who don't care...), but it still is a signal.
• A solar warm water system is cost-effective in many regions. Consider this especially if you have a pool or other large consumer.
• Most important is probably to work towards a general recognition that this is a problem, but that many solutions have upsides that compensate for costs (better quality of live, cleaner environment, less dependency on foreign oil, more jobs in new industries). Existing large players stand to lose (e.g. the oil and coal industry), but the overall economic impact may well be positive. Germany, e.g., is creating a lot of high-tech jobs in the solar and wind energy industries. Pro-environment does not have to be anti-market! --Stephan Schulz (talk) 13:27, 13 May 2008 (UTC)

I know someone mentioned this above, but I'm not sure it was taken seriously - eating vegetarian is probably the most influential thing a person can do to personally reduce climate change - according to a recent UN report, http://www.un.org/apps/news/story.asp?NewsID=20772&Cr=global&Cr1=environment, "Cattle-rearing generates more global warming greenhouse gases, as measured in CO2 equivalent, than transportation". Pretty impressive. --Bmk (talk) 19:20, 13 May 2008 (UTC)

It is indeed astounding how little useful information can be found about this. Switching to fluorescent lamps is mentioned quite a lot, but lighting only represents a few percent of CO2-emissions. As I understand it, the really big energy guzzlers are transportation and heating/airco, which together cause almost half the CO2-emissions. Of course, with the temperature control it depends a lot on where you live (hot or cold climate). Wearing a sweater indoors in winter in a cold climate can help a lot. Concerning transportation, options range from keeping your car tires sufficiently inflated to living close to where you work (or vice versa). Most cars are waaaaay to powerful, so get the most energy-efficient one (can still be luxurious - why not?). And don't accelerate too fast. That really makes a big difference and it one of the easiest things to do. And of corse, in concurrence with Zain, the easiest thing you can do is vote for the party that is most focused on solving this problem (both the reduction of energy use and the development of alternative energy sources). I've been doint that for over ten years now. I've become a one-issue voter. DirkvdM (talk) 08:34, 14 May 2008 (UTC)

I think one of the reasons why fluorescents often come up is because even though the amount they contribute may be small, switching is easy to do, relatively painless for the vast majority of people and generally quite cost effective even in the relatively short term. Improving insulation, particularly in temperate countries, is another common suggestion but it can be expensive. Common methods to try and do this include better building standards, so all new homes at least have a resonable degree of insulation and some sort of tax relief for people carry out renovations to improve their insulation. Over powered cars is a factor, but it's something difficult for governments to deal with directly without too much controversy. But resonable petrol taxes for example, which encourage the efficient use of petrol (and therefore the use of energy efficient i.e. not overpowered cars) can help (they also have the added bonus of reducing the subsidy other people pay to road users and making it easier to subsidise things like public transport which have a far greater benefit then excessive road building). The recent high price of petrol has definitely helped, particularly in the US which has always had very low petrol taxes compared to much of the rest of the world although it hasn't always had the completely desired effect (for example, the growth in hybrid SUVs in the US which will good, it would have been far better if the people had chosen less overpowered vehicles). Stuff like going vegetarian, which while an excellent idea in practice, isn't something you can convince a lot of people to do Nil Einne (talk) 11:42, 19 May 2008 (UTC)

Protoplast fusion

while performing protoplast fusion we have to chop leaves into very fine peices before proceeding for actual fusion. so why don't the cells die out at that moment?--Kayatheangel (talk) 13:19, 12 May 2008 (UTC)

Presumably the cellular metabolism continues. Plant cells may not have to be so isolated from their neighbours by an intact cell wall to function in the short term. You would have to keep a large number of the organelles intact. Some of the membranes could reform spontaneously. The cells would die in the natural environment when chopped apart, because they would dry out and lose their root nutrient supply. Graeme Bartlett (talk) 21:46, 13 May 2008 (UTC)

Finding CpG islands with genomic databases

How do I determine which area of a gene can be designated 'CpG' island? Suppose that I'm interested in this gene; I vcan see that it has a lot of CpGs but can I get a program (preferably online) that defines the CpG island(s)? ----Seans Potato Business 13:34, 12 May 2008 (UTC)

• http://www.cpgislands.com/
• http://www.bioinformatics.org/sms2/cpg_islands.html
• Or, normally, you can go to the contig viewer in Ensembl [1], go to the "detailed view" section and in the menu bar, click on the "features" tab. The check the "CpG island" check box, close the tab, it you should see a track on the viewer showing islands in the context of your gene. Ensembl seems to be having technical issues at the moment, and it finds an error when I do it, but it should be working again soon. Rockpocket 19:47, 12 May 2008 (UTC)

Widely-distributed, semi-technical history of moon shot?

Was there anything like the Smyth Report for the Apollo program, or for the Apollo 11 mission (moon landing) specifically? The Smyth Report was a government-produced history of the atomic bomb that came out contemporaneously with its use, to explain in more detail what people were seeing on the front pages of newspapers after the bombings of Hiroshima and Nagasaki. Anything like that for the space race? I don't mean official histories that came out years later, or unofficial histories/popularizations. --140.247.242.128 (talk) 17:16, 12 May 2008 (UTC)

While I can't directly answer the question, bear in mind that the Apollo program, and the related programs preceding it, were carried out in view of the public, in contrast with the secret Manhattan Project. There is not, as a result, the need for a parallel to the Smyth Report. — Lomn 19:45, 12 May 2008 (UTC)

Oceans, Lakes, and Seas

What is the differance between an ocean,lake,and a sea? —Preceding unsigned comment added by Unclejojo (talk • contribs) 17:43, 12 May 2008 (UTC)

(I made a new section, if no one minds) An ocean is a large salty body of water that is part of Earth's main body of water, a lake is a body of water surrounded by land, and a sea is a body of salt water surrounded by land and connected to the ocean (however, some salty lakes are called seas). 206.252.74.48 (talk) 18:46, 12 May 2008 (UTC)

A "sea" can also be a (pretty arbitrary) geographical region of an ocean, for example, the Sargasso Sea, the South China Sea.

Atlant (talk) 19:05, 12 May 2008 (UTC)

Well, you would know, Atlant! I'll also point out that in addition to the above usages, the Earth's main body of water can be called "the ocean" or "the sea". --Anonymous, 22:27 UTC, May 13, 2008.

:-). It's not a coincidence, by the way.

Atlant (talk) 17:14, 14 May 2008 (UTC)

So the Salton Sea and the Dead Sea are lakes. Edison (talk) 03:38, 14 May 2008 (UTC)

Earthquakes

I understand how earthquakes start - the release of pressure from two tectonic places which are pushing against each other or rubbing across each others boundary's - but how do earthquakes stop? What stops the plates from continuing to move? Mr Beans Backside (talk) 18:08, 12 May 2008 (UTC)

As I understand it, the plates are moving pretty much the whole time. An earthquake happens when the plates get stuck and pressure builds up until it is forcefully released and the plates continue moving again. --Tango (talk) 18:18, 12 May 2008 (UTC)

Or put another way, the plate portions right at the boundary get stuck again when enough strain energy has been released. Stress starts to build up again, since the plates as a whole are moving, but they are jammed against each other at the boundaries. Rub your fingers hard across a rough surface - you hand is moving continuously, but your skin is stopping and starting. Franamax (talk) 19:16, 12 May 2008 (UTC)

What you describe are interplate earthquakes. There is another kind Intraplate earthquakes. They are rarer, but generally more destructive. You might also want to have a look at Subduction. Lisa4edit (talk) 20:21, 12 May 2008 (UTC)

Paleontology

How do paleontologists determine the sex of a fossilized creature? Mr Beans Backside (talk) 18:09, 12 May 2008 (UTC)

I think it depends on the creature, but there are usually things that differ between the sexes. The total size, the size of certain body parts, the shape of certain body parts, etc. --Tango (talk) 18:16, 12 May 2008 (UTC)

But all you would have is bones? Does the bone structure differ between the sexes? Mr Beans Backside (talk) 18:24, 12 May 2008 (UTC)

Bone structures often (although not always) differ by sex. If the creature is extant (still alive somewhere), the skeletons of the male and female can be compared for differences. The specific differences between sexes vary by species. For instance, the presence of a baculum is an indicator of male (although females can have a baubellum) in most mammals; likewise antlers in deer, pelvic structure in humans, etc. might be used. For extinct species the work is mostly analogy to living relatives, although this can be difficult. The use of ancient DNA has also been able to shed light on some of the more recently extinct creatures. Some genetic work on moa (extinct, flightless birds of New Zealand), for instance, was able to show three "species" (classified by bones) were really one species of bird but of different sexes (two sexes, of course, the original classifier, Richard Owen working in the 19th century, had based the distinction largely on size). --TeaDrinker (talk) 18:31, 12 May 2008 (UTC)

Our Tyrannosaurus article has some interesting bits on this topic. Matt Deres (talk) 20:14, 14 May 2008 (UTC)

Male to female ratio

Human offspring are roughly balanced 50% male to 50% percent female. Does this balance exist throughout nature, or has evolution resulted in more useful proportions for some species? For example, more male dear because some might die fighting each other. If proportions are unbalanced in some species, how does this work? Mr Beans Backside (talk) 18:45, 12 May 2008 (UTC)

Have you read sex ratio? -- Coneslayer (talk) 18:49, 12 May 2008 (UTC)

I'm not sure but I think animals like aphids have females or males which can reproduce asexually during certain seasons. Surely this would create such an 'unbalance'. Regards, CycloneNimrod^Talk? 18:51, 12 May 2008 (UTC)

Actually the human sex ratio is not balanced at birth, since males tend to die faster. Evolution has resulted in this proportion, 50.5:49.5 as a response.

In some other species, the sex-ratio changes in response to food availability, more males in times of abundance, more females in times of scarcity. Franamax (talk) 19:21, 12 May 2008 (UTC)

More detailed answers: Wikipedia:Reference desk/Archives/Science/2007 October 26#gender ratios in a species. Rockpocket 22:01, 12 May 2008 (UTC)

Does the universe spin?

The planets, solar systems, star clusters, and galaxies all spin. Does the universe itself spin? Mr Beans Backside (talk) 19:58, 12 May 2008 (UTC)

We have no evidence that it does and no reason to expect that it would. The systems you mention, from planets to galaxies, are all examples of systems that have coallesced under the force of gravity. Gravitational contraction preserves any initial angular momentum a system may have had at random, and as a result amplifies a system's rate of rotation. However, by contrast, the universe as a whole is not a gravitationally collapsed system, and hence the same dynamics will not apply. Dragons flight (talk) 20:04, 12 May 2008 (UTC)

Apparently there are a lot of bored theorists, cause it isn't that hard to google papers on rotating universe versions of cosmology. This quotes a limit of 2×10⁻¹³ radians/year, or one revolution every 30 trillion years. Dragons flight (talk) 22:17, 12 May 2008 (UTC)

Hot, thankee. WilyD 13:10, 13 May 2008 (UTC)

This is making my head spin

Isn't "spinning" defined in relation to surrounding space? But what if there is no surrounding space? How could you tell the Universe is spinning if you have nothing outside the Universe to compare its changing position to? Just curious.  :)  The Transhumanist 21:28, 12 May 2008 (UTC)

Excellent question, and not an easy one to answer. I'm not sure if there even is a generally accepted answer. Consider this: You have two masses connected by a string, you set them spinning around their common centre of gravity and the string will go taut. What happens if you do it in an otherwise completely empty universe? They're not spinning with respect to anything else, since there isn't anything else, so does the string go taut? --Tango (talk) 21:39, 12 May 2008 (UTC)

Yes the string would go taut, the physics to calculate this does not involve any other entity. spin is not relative. It is a bit too abstract for me to talk about an entirely empty universe, instead consider a very empty space, very large space, you know the string would be taut in this case. If you want some more interesting physics, Black holes preserve angular momentum as one of the few properties that exists beyond the event horizon. GameKeeper (talk) 22:35, 12 May 2008 (UTC)

The short answer is "no" - you can tell if something's spinning due to the appearence of interial forces, namely the "centrifugal force". I don't believe this has ever been measured for the universe, which'd give some low upper limit, but I don't know what it is. WilyD 21:57, 12 May 2008 (UTC)

I'll back up this 'no'. Spin is not relative, it's not measured in relation to the surrounding space but can be absolutely determined due to the accelerations it involves. The maximum spin of one revolution every 30 trillion years (as mentioned above), would mean the universe would have to be 2000 time older than current best estimates before it did one rotation. Something rotating at a maximum of such a rate most definitely would not be described as spinning. GameKeeper (talk) 22:27, 12 May 2008 (UTC)

You can construct theoretical models of a rotating universe. There's no axis of rotation (much like there's no center to the expansion), but there is a direction (of the angular momentum vector), so these models violate the cosmological principle. This would be visible as an anisotropy in the cosmic microwave background. There was actually a claim a few years ago that such an anisotropy does exist (astro-ph/0502237). I don't know what the current status of this is, but the evidence for it is weak at best. -- BenRG (talk) 23:35, 12 May 2008 (UTC)

I'm surprised no one has mentioned Mach's principle. -- BenRG (talk) 23:35, 12 May 2008 (UTC)

Yes of course, that's why I left this thread alone. Basically (if I understand it right), the only way you know for sure you're spinning is because of the presence of distant "fixed" stars. It is the presence of those incredibly distant stars that establishes your own local inertial frame. Put another way, if the whole universe was spinning, how would you know? There would be nothing to measure it against, and you could equally say that the whole non-universe was spinning and the universe was standing still. It would make no difference. Franamax (talk) 03:12, 13 May 2008 (UTC)

Of course, there's no particular reason to believe Mach's principle is true... WilyD 04:42, 13 May 2008 (UTC)

One could easily apply Newton's Bucket argument instead - which seems just as reasonable, and experimentally indistinguishable. WilyD 04:44, 13 May 2008 (UTC)

Newton? That hack couldn't even dodge a falling apple! Reading through that article, beyond the fact that there is an external observer of the bucket, I see "true motion can be understood only in reference to absolute space" - but the notion of absolute space has been pretty throughly destroyed, along with absolute time. We're only left with relativity, and Mach used the relation to fixed/distant stars. The central axis of the bucket is pointing to one particular star, the rotating reference frame of the water is defined by the fact that other distant stars "revolve around the bucket". The point here though is that if there is nothing outside the bucket-universe, "spinning" loses all meaning, you can't define spinning if there's nothing outside to look at. That article could probably use an update to elaborate how the view of absolute measurement has since fallen apart. Franamax (talk) 07:25, 13 May 2008 (UTC)

Without doing the same experiment in an empty universe, you cannot establish Mach's Principle - there's no result anywhere, either theoretical or observational, to invalidate the bucket experiment - it does, in fact, demonstrate that linear motion is relative, but accelerations are absolute - this is the result of GR - all Mach's Principle suggested is that mass is normalised by the mass of the universe. I would argue GR is suggestive of Bucket, not Mach, but it's really neither here nor there until we get a second universe to test in. WilyD 13:09, 13 May 2008 (UTC)

It's a curious observation that many people seem naturally predisposed to think of motion as absolute and rotation as relative, when the laws of physics, as deduced over time from detailed observation of how things actually work, say it's exactly the other way around. I suspect it's because, in the everyday world we live in here on Earth, there exists an obvious absolute reference for motion (the Earth itself), but no such reference for heading, the Earth's surface being, to a first order approximation, anisotropic. We then, somehow, are prone to generalize this lack of an absolute reference from heading to rotation; even though centrifugal and Coriolis effects should be familiar to anyone who has ever ridden a carousel, somehow our conviction of the relativity of rotation is so strong that many, if they puzzle over the seeming contradiction at all, end up concluding that these effects must result from some unseen influence of the surrounding, "counterrotating" world.

Perhaps it's because humans tend to be visually oriented creatures, whereas the direct effects of absolute rotation upon our own bodies are only observable through the non-visual (kinesthetic and balance) senses. If you're sitting in a rotating chair in a windowless room, to your eyes it makes no difference if it's the chair or the room that rotates, even though, if the speed is more than a few rpm, the difference would be easy enough to feel. We don't trust our muscles and inner ear as much as we trust our eyes, and if we notice the discrepancy, it's easy enough to suspect that our non-visual senses are somehow detecting the orientation of the Earth through the walls; after all, we sense the Earth's gravity too, don't we? And the same argument can be used to explain away any other means of directly detecting the rotation of our hypothetical room, such as by holding a pendulum and seeing if it precesses or by watching the surface of water in a bucket: maybe the Earth "counterrotation" is also affecting the motion of the pendulum and the water, just as it, so the explanation goes, affects our inner ear.

Of course, counterexamples to these simple theories of "relative rotation" are easy to find, but the catch is that the theory can always be extended, for example by assuming that the rotation we feel isn't actually relative to the Earth, or to any other nearby mass, but to the entire mass of the Universe. And since we can't actually give the entire Universe a spin and see what happens, the theory then becomes unfalsifiable. Of course, at that point Occam's razor should suggest that there are easier explanations, but this does not make a particularly convincing argument if one's intuition says otherwise, particularly if one is not sufficiently familiar with physics to see that the theory without these "Machian" effects really is simpler. —Ilmari Karonen (talk) 18:53, 13 May 2008 (UTC)

Cloned fingerprints

Would a genetic clone have the same fingerprints as the original? Mr Beans Backside (talk) 20:05, 12 May 2008 (UTC)

I seem to remember hearing that identical twins have different fingerprints, so I would expect a clone to have different prints too. --Tango (talk) 20:08, 12 May 2008 (UTC)

Similar but not identical.[2] There are lots of sources on this. Gwen Gale (talk) 20:18, 12 May 2008 (UTC)

Are fingerprints also dependent on environmental factors? Would that cause a sufficient difference for them to be distinguishable? Mr Beans Backside (talk) 20:24, 12 May 2008 (UTC)

Yes. Gwen Gale (talk) 20:26, 12 May 2008 (UTC)

Hi. On the other hand, irises are even more unique than fingerprints. Even identical twins will have different iris patterns. Hope this helps. Thanks. ~AH1^(TCU) 23:10, 12 May 2008 (UTC)

I would expect clones would have an even greater difference then an identical twin since it would have a far greater environmental difference (in the womb) then a twin Nil Einne (talk) 16:34, 14 May 2008 (UTC)

shortwave radio

hi, I am interested in buying a shortwave radio (not to transmit just to receive) but am interested in hearing ham radio too.

I am confused as to if i need ssb (short sideband??) with also usb, lsb and cw.

can someone clarify? also can i spend $100/£50 rather than a lot , if so please post a link.

thx —Preceding unsigned comment added by 78.144.146.123 (talk) 21:25, 12 May 2008 (UTC)

According to our article on Single-sideband modulation, you will need it to hear ham radio. See also sideband for more info on bands. As with most things, you get what you pay for, the cheaper radios seem to only receive normal shortwave broadcasts. You might also need a big antenna to pick up ham transmissions. Try googling "buy shortwave radio", there are hits for information and purchasing. Franamax (talk) 22:06, 12 May 2008 (UTC)

Just to get the terminology straight, if a radio is capable of receiving "Single Sideband" (SSB), it can receive either the "Upper Sideband" (USB) or the "Lower Sideband" (LSB). It can also receive Morse code ("continuous wave"/CW) transmissions. And I think any radio that can receive SSB (as used by most amateur radio operators) can also receive ordinary amplitude modulation (as used by most commercial and state-run shortwave radio stations. But not all AM radios can receive SSB; that takes extra circuitry in the receiver.

Atlant (talk) 00:33, 13 May 2008 (UTC)

Trivia note: if you're driving in Canada and see a license plate starting with "VE", that's a ham radio operator, the license number is their call-sign, they get it for free. Ram their car, you can ask them all sorts of questions while you wait for the police ;) Franamax (talk) 03:05, 13 May 2008 (UTC)

For several decades, amateur radio "hams" have used ssb for their voice transmissions, because it transmits farther for a given power limit and per government regulatins. Without SSB your receiver would only make their transmissions sound like Donald Duck. Look for a receiver with SSB. A Beat frequency oscillator (BFO) is needed to pick up Morse code transmissions. A radio which picks up SSB should also pick up CW (Morse code). Without the BFO capability, a radio would only pick up shortwave transmissions like goverenment radio stations (news, propaganda, etc). I have used a radio frequency signal generator with a non-ssb receiver to pick up ssb and cw transmissions, but I do not recommend it. Edison (talk) 04:34, 13 May 2008 (UTC)

Ordinary cheap shortwave receivers will have a difficult time picking up amateur radio signals. The problem is that the normal broadcast stations have a much stronger signal which will cause the weak HAM radio signal to become swamped in intermodulation noise. You need a more expensive communications receivers to be able to enjoy listening to HAM radio. If you want a good deal, you should try to get hold of a second hand communications receiver. There are many exellent communications receivers that are no longer manufactured that would cost you $1000 or more if bought new. But the second hand price will be significantly lower. E.g. why not buy a second hand Kenwood R-5000? Count Iblis (talk) 13:42, 13 May 2008 (UTC)

I have picked up hams as well as international broadcasters on old and cheap sw receivers. The broadcasters tend to be in different bands from the hams. Also the ham might be in the next town and the internatinal broadcaster might be a continent away. But CW and SSB are tricky to receive without the aforementioned special circuitry. Radio Shack had a fairly cheap receiver a few years ago which included SSB and CW reception. Edison (talk) 03:36, 14 May 2008 (UTC)

Don't know if that would affect what you are looking to set up, but have a look at Scanner (radio)#Legal issues before you get yourself into trouble. Disclaimer: Not advice, just a friendly hint.Lisa4edit (talk) 05:33, 14 May 2008 (UTC)

Edison, I agree. However, the fact that the hams operate in different bands is not enough for the cheaper radios to prevent strong intermodulation effects. Even on my R-5000 I can notice very small intermodulation effects if I listen to air traffic communication on, say, 5658 KHz. This is because when you tune to that frequency the RF stage will let the frequencies in some block through that in case of the R-5000 includes the 49 meters band. And then it is inevitable to get third order intermodulation effects caused by powerful stations on 49 meters band. This problem is much more severe on my cheaper radio. What is especially annoying is that if you listen at night (on the cheaper radio) the intermodulation effects will drown out even strong signals on the 5600 khz band.

So, before you buy a radio, you should really think about what your primary focus will be. If it is listening to broadcast stations and to ham stations, the latter only occasianaly and it wouldn't be a big deal if you can't some stations, then you could go for a radio priced $100 or even cheaper. But if you would be dissapointed if you can't receive amateur stations very well you should consider spending just a few hundred dollars more to buy a good second hand communications receiver. Count Iblis (talk) 17:38, 14 May 2008 (UTC)

Sociocultural evolution

Sociocultural evolution, the progression:  Hunter-gatherer bands → Social rank → tribes → Social stratification → chiefdoms → Neolithic Revolution →→→ Civilization: Agrarian society (Pre-industrial society): Agrarian villages → Towns → Cities → City-states → Nation-states →→ Industrial Revolution → (Modern) Industrial society →→ (Postmodern) Post-industrial society → Informational Revolution → Information society → Digital Revolution →→ Globalization → World government?

Is that correct?

The Transhumanist 21:30, 12 May 2008 (UTC)

you missed off this one:

http://en.wikipedia.org/wiki/United_Federation_of_Planets —Preceding unsigned comment added by 78.144.146.123 (talk) 22:13, 12 May 2008 (UTC)

Is it correct? Only if you assume evolution of this sort is both linear (non-branching) and teleological (driven towards a specific end). Neither of which are reasonable assumptions (or supported by evidence) in either biological or sociocultural evolution. --98.217.8.46 (talk) 00:41, 13 May 2008 (UTC)

The thing which might make World government inevitable is the failure of so many to have achieved the first tier and fewer the next and so on. -- Taxa (talk) 01:41, 13 May 2008 (UTC)

You missed out religion, which has always played a major role in social development (kings often relied on a priest-class to confirm their divine origins). That influence has varied through time and directed sociocultural evolution into several divergent paths. (Note, you can always play Civ3 to check your theory out:) Franamax (talk) 03:01, 13 May 2008 (UTC)

That seems more or less a correct hierarchy of least to most complex societies. Keep in mind that societies, as 98.217.8.46 implied, may move "backwards" so to speak. The collapse of the Roman Empire was a step back from the nation-state to the city state for parts of Europe. They may also skip steps. The Native American tribes have pretty much been absorbed into the American nation-state.

Durant has a hierarchy of his own going:

• family
• clan: a group of related families occupying a common tract of land, having the same totem, and governed by the same customs or laws
• tribe: a group of clans united under the same chief
• state: based on geographical contiguity rather than kinship
• ...

I'm sure he goes on, though I haven't gotten very far in The Story of Civilization. — Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 05:45, 13 May 2008 (UTC)

An excellent read along with The Story of Philosophy. 71.100.14.205 (talk) 11:02, 13 May 2008 (UTC)

Brown versus green (fuel/CO₂ versus O₂ production)

Suppose I have 50 acres covered with a 15 year old stand of pine trees (another 5 years of growth needed to become suitable for harvest as lumber) for which I'm offered a certain amount to harvest now. The amount of the offer sounds reasonable but a higher reward might be possible from firewood than lumber. Before I make a decision I need to know how much energy and carbon dioxide the stand can produce and how much oxygen will be lost in order to make the right green decision. Is there a template I can use to facilitate this analysis or is all this talk about green just meaningless theory? 71.100.14.205 (talk) 22:02, 12 May 2008 (UTC)

If you want to reduce CO₂, then lumber is the way to go. If you burn the wood, all the CO₂ gets released back into the atmosphere, if you keep it as wood, it's stored up. --Tango (talk) 10:47, 13 May 2008 (UTC)

Unfortunately economics have to be made part of the equation such as in maximizing the profit by using the energy availability as a positive and the co2 output as a negative. A template for determining the amount of timber per acre would probably help. 71.100.14.205 (talk) 11:27, 13 May 2008

(UTC)

The "economy" depends on you location. This link gives one example for US Mississippi [3]. This may not be representative or relevant to your location. Ecologically the more uses a product gets before it is decomposed the better. Your timber will eventually either rot or get burned, but can go through quite a few cycles of use in-between. 71.236.23.111 (talk) 20:04, 13 May 2008 (UTC)

If you want to reduce CO₂, then lumber is the way to go. If you burn the wood, all the CO₂ gets released back into the atmosphere, if you keep it as wood, it's stored up.

But if this used as a substitute for fossil fuel use then the answer is not clear cut. Would it save more than sequestration through lumber? -- Q Chris (talk) 07:12, 14 May 2008 (UTC)

In Australia at least, the pine would have a much greater dollar value as lumber (and pine bark potting mix) than firewood anyway.Polypipe Wrangler (talk) 20:31, 15 May 2008 (UTC)

Ergonomics of press-up exercise

Are press-ups an ergonomic exercise or do they cause undue strain on the wrists? ----Seans Potato Business 22:04, 12 May 2008 (UTC)