Wikipedia:Reference desk/Archives/Science/2009 March 19

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March 19

Natasha Richardson's fall

She didn't hit anything. Could the fall have been the result of a brain condition? How may a simple fall cause such a death. 69.203.78.244 (talk) 03:48, 19 March 2009 (UTC)

It can take surprisingly little to cause a serious head injury and what seems like a minor injury can become life-threatening very quickly. See traumatic brain injury. (And wear a helmet. They save lives.) - Eron^Talk 03:59, 19 March 2009 (UTC)

Complete and utter speculation based on TV medical dramas and 'stuff I read somewhere' here - but AFAIK, a bang to the head can cause a bleed in the brain which, whilst not immediately fatal (or even apparent) can continue to leak blood into the surrounding spaces in the following hours. Eventually, if there's no more space for the blood to go, the intercranial pressure starts to build up to a dangerous level and the brain starts to gets squeezed. Without immediate medical attention, the base of the brain gets squeezed out, toothpaste-like through the hole in the base of the skull - at which point, the only effective treatment for the condition is a pine box. --Kurt Shaped Box (talk) 04:03, 19 March 2009 (UTC)

Since there's no publicly released information about the mechanism of injury or her medical condition, any response to this question is purely speculative as it applies to Ms. Richardson, and what follows is not intended to imply any one mechanism or cause of death, only what is possible.

That said, the are numerous ways a person could die from a closed head injury, including the slow bleeding scenario KSB described, which is usually a subdural haematoma. Other causes attributable to bleeding include extradural haemorrhage, subarachnoid haemorrhage, although this usually has a more precipitous onset, and intracerebral haemorrhage, to name a few. There are many conditions that increase the risk of some of these catastrophic bleeding problems, some of which are berry aneurysms and arteriovenous malformations. Contre coup type head injuries, and other blunt force, closed-head, traumatic injuries can lead to death through increasing cerebral oedema, ultimately causing the herniation of the lowest parts of the cerebellum throught the foramen magnum, which causes compression of the brain stem, where important things like consciousness, breathing and heart rhythm are controlled. This causes death. This is the process KSB described above, and is described by many doctors as "coning." It is caused by anything that increases intracranial (inside the skull) pressure sufficiently. More obscure causes in the setting of trauma exist, the first that comes to mind is acute high-pessure hydrocephalus that can be caused by a colloid cyst of the third ventricle blocking drainage of cerebrospinal fluid from the lateral ventricles. I could go on, but I won't! Mattopaedia ^{Have a yarn} 06:07, 19 March 2009 (UTC)

It is reported that it was an epidural haematoma which sadly affected Natasha. This occurs when a bleed occurs in your head, between a layer called the dura and the skull. This causes an increase in intracranial pressure, resulting in a sort of compressive mechanism on the brain. Roughly 15-20% of people die from this condition, often because it's not as easy to diagnose as the other haemorrhages and haematomas listed above by Mattopaedia. —Cyclonenim (talk · contribs · email) 07:45, 19 March 2009 (UTC)

But she didn't hit anything, if the reports are correct! Thanks for the impressive list, too--though the skull is strong it's crazy how many ways the brain can go wrong. 69.203.78.244 (talk) 13:18, 19 March 2009 (UTC)

Brain injuries don't require an external impact. Sudden deceleration can do it, too, due to the brain's inertia causing it damage when it slams against the inside of the skull. StuRat (talk) 14:21, 19 March 2009 (UTC)

And, she did hit something - she hit the ground. That acounts for both impact and sudden deceleration. This story quotes a couple of ski patrollers who note that falls on flat sections of ski runs can be more dangerous than falls on slopes, as the skier just drops and stops rather than tumbling or sliding down the hill, which can absorb some of the impact. - Eron^Talk 15:04, 19 March 2009 (UTC)

Indeed - I can tell you from experience that compacted snow is very hard. I've hit my head on the ground after a skiing fall, and it isn't pleasant (I've never required hospitalisation, fortunately). The worst such time was, indeed, on a flat section - right at the bottom of a dip, so I was going flat out, hit a bump, hit the ground and stopped immeadiately. I was completely dazed for several seconds. I don't find it at all hard to believe that someone less fortunate than me could get a fatal head injury from a similar fall. --Tango (talk) 19:16, 19 March 2009 (UTC)

Yellow cheese

What causes some cheeses to be yellow/orange? 99.245.16.164 (talk) 03:53, 19 March 2009 (UTC)

Annatto. Cheers! --Jayron32.talk.contribs 04:00, 19 March 2009 (UTC)

Also Vitamin A or beta-Carotene. On European labels E160 or E160a. 76.97.245.5 (talk) 05:21, 19 March 2009 (UTC)

A possible problem with spinning for Artificial Gravity

I have heard several way involving spinning a ring, or surface, or something to create centrifugal force for artificial gravity. I have always wondered: What would happen if I jumped up off the surface? Once I lost contact with the spinning surface, would I be weightless, or would my velocity bring me down again? Tiailds (talk) 04:18, 19 March 2009 (UTC)

If you start out spinning with the ring, you will have a lateral velocity. When you jump, that lateral velocity component does not change, so you will continue moving in that direction until you encountered the ring again. You will also have some amount of angular momentum, that will keep you rotating with the ring, so you will likely land in a roughly upright position. In extreme cases this would not be true and you could land at an awkward angle.

In contrast, if you started running in the direction opposite the ring rotation and managed to match that rotation, the centrifugal force would disappear and a jump would launch you into a weightless condition with the ring rotating around you. You could almost think of this as the equivalent of achieving orbital velocity in this inside-out environment. -- Tcncv (talk) 04:55, 19 March 2009 (UTC)

(EC with above)The idea is that you are on the inside of the spinning surface. Under those conditions, regardless of where you jump from, your straight-line motion (which your inertia will have once you are no longer in contact with a rotating frame of reference) will always bring you back into contact with the surface again. It's the centripetal force which is spinning the ring or whatever that provides you with that motion, not centrifugal force (a fictional force), which is really just the effect of losing contact with a rotating frame of reference and not a real force at all. Since your tendancy will be to move away from the center in both cases, being OUTSIDE the spinning ring will cause you to drift away, but being INSIDE the spinning ring will cause you to always drift into the ring. So you fall back to your "ground". --Jayron32.talk.contribs 05:08, 19 March 2009 (UTC)

Obligatory xkcd reference. There would also be a slight effect from the Coriolis effect, moving you a little in the direction you're spinning when you jump. — DanielLC 16:06, 19 March 2009 (UTC)

This "FreeFall" strip is more applicable than the xkcd one. It matches what Tcncv was saying. APL (talk) 19:16, 20 March 2009 (UTC)

I spent a year and a half on Mars and all I got was this stupid t-shirt...

I have a few questions about a manned missions to Mars which Manned mission to Mars sadly does not answer:

1. First of all, what would be the length of such a mission? I hear people say that the trip there would take 3 months or so, but the entire trip would take much longer, wouldn't it? I mean, once you've taken three months getting there, haven't you pretty much missed your window of opportunity to get back? The article on exploration of Mars states that the launch window comes around every 780 days, so would that mean that the poor astronauts would have to spend something like a year and a half living on the surface of Mars? I'm having trouble even imagining how much food and fresh water you'd need to bring to stay alive that long (not to mention the psychological effects, I've read The Three Stigmata of Palmer Eldritch).
2. Second, what about communications with Earth? I mean, when Earth and Mars are sort-of near to each other, it wouldn't be much of a problem (you could live with a twenty minute latency, even if it's a pain in the ass), but assuming I'm right on part number one (a bold assumption), for most of the mission, Mars and Earth would be on opposite sides of the sun! Can you reliably communicate with someone when the sun is up? I'd imagine that the interference would be huge.
3. Third, what tangible benefits would a manned mission to Mars yield? Yes, I get the whole "triumph of the human spirit" thing and it would make a great television event, but if we just went up there to make measurements and bring back rocks for analysis, can't we just get robots to do that? I mean, yeah, the rovers didn't bring anything back, but I imagine it would be WAY easier to make a return trip with a robot compared to making one with a human being. No need to worry about some dude going ape-shit crazy and slaughtering the rest of the crew for one thing (presumably the robot would have a "become_self_aware = false" line in its code somewhere).

Can any of you fine scholars enlighten me on the subject? Belisarius (talk) 05:25, 19 March 2009 (UTC)

I'll comment on the second point only. The Sun would certainly block communications when directly in line between Earth and Mars, although that configuration might never occur during the mission (the two planets orbit in different planes, remember). I don't know about the more likely situation where it is almost directly in line, but experiments could be done to find out if it is a problem. And if it is, the thing to do is launch a communications relay satellite into a solar orbit that will keep it far enough away from the Earth-Sun line.

For single-mission use there would be a wide choice of orbits, but for long-term stability, the obvious thing is to use one of the Trojan positions, 60° ahead of behind of the Earth in its orbit. Incidentally, this solution was anticipated in science fiction as early as 1942, with George O. Smith's lighthearted Venus Equilateral stories. Smith was writing in the days of vacuum tube electronics and assumed the relay station would be manned -- as did Arthur C. Clarke when he invented the geosynchronous communications satellite in a nonfiction article about the same time. Smith's first story, "QRM—Interplanetary", is particularly worth looking for. --Anonymous, on Earth, 08:59 UTC, March 19, 2009.

(A) We're not talking about a solo flight. so the 790 days in point one wouldn't be spent in isolation. I would imagine an expedition consisting of a number of ships - minimum three - and dozens in the crew. (B) Magellan's Victoria took three years to circumnavigate the globe; FitzRoy's second Beagle expedition - the one with Darwin - took five. (C) Supplies need not all be carried along. Unmanned ships stuffed with MREs could be launched separately - starting before the manned component - and either inserted into orbit or dropped to the surface. (D) BTW, a second on the Venus Equalateral recommendation. B00P (talk) 09:40, 19 March 2009 (UTC)

While you're right we're not talking about a solo flight, the psychological effects of such a long trip in which a few people will be in constant close contact and very far from earth with limited contact are definitely something that has received a great deal of consideration (as with the physical effects) and is one thing that has been studied in numerous ways (e.g. [1] & [2]). Take a look at [3] and is also mentioned in Manned mission to Mars. I saw one suggestion a while back that choosing too many astronauts which are too perfect, as is the norm may actually be a mistake because they may not get along very well with each other over such a long time so there are definitely lots of different ideas. Basically of course, we will never know until it happens since there's no way you can simulate the conditions exactly. P.S. I've never heard a suggestion of multiple simultaenous crewed ships before. While I'm sure it has been proposed somewhere, I don't think it's high on the current list of ideas. Nil Einne (talk) 13:19, 19 March 2009 (UTC)

As having groups of people who can get along well together for years in confined spaces would be critical for the mission, they should make each group go through a test run for several years of isolation first. StuRat (talk) 19:00, 19 March 2009 (UTC)

That would be an extremely inefficient use of time. A 6 month spell on the ISS together might be good, although not all the people that would go on such a mission would be useful on the ISS (there aren't many rocks for geologists to study in LEO!). --Tango (talk) 19:04, 19 March 2009 (UTC)

The isolation test could be done on Earth, in an old bomb shelter. No need for any major expenses. StuRat (talk) 14:53, 22 March 2009 (UTC)

As for supplies, such a mission would likely benefit from far more recycling than is currently done. Oxygen could be recycled from the air, and carbon dioxide removed (and maybe used to grow plants). Water could be recycled from the air (respiration and evaporation from skin and eyes) and from urine. Recycling food could also be done, say by using feces to grow food. Mushrooms, anyone ?

Another option is to produce some of the things we need directly on Mars. There is water ice at the poles, which could be used to supply water, and, after some electrolysis provided by solar power, oxygen. StuRat (talk) 11:55, 19 March 2009 (UTC)

An interesting thing that happens with my local NPR radio station periodically is that they'll say "at about X o'clock today, we'll lose transmission of this program due to the Sun passing behind the satellite that gives us our feed". And that's with your transmitter in front of the Sun. --Sean 13:34, 19 March 2009 (UTC)

Manned mission to Mars still has that elephant of "Health threat from cosmic rays" in the closet. I haven't seen us make all that much progress in figuring out sufficient shielding. (Nanotube polymers are a very nice theory, but the spaceship would need more than a thimble full.) As to why, sooner or later our own planet is going to face a huge calamity. It would be nice for the survival of the species - if you are interested in that - to have a population stashed elsewhere by that time. If we intend to head in that direction we'd have to start some when somewhere. 76.97.245.5 (talk) 15:26, 19 March 2009 (UTC)

I may be misreading this, but in the original post, Belisarius says, "...Mars and Earth would be on opposite sides of the sun! Can you reliably communicate with someone when the sun is up?" The phrase "sun is up" usually refers to it being daytime and the earth does not orbit the sun during the course of a day, but over the course of a year. The sun being "up" would not necessarily be a problem; the sun being "between" would certainly be. Matt Deres (talk) 17:02, 19 March 2009 (UTC)

Yes, but you can only communicate when the Earth is above the horizon, which would be at the same time as the Sun was above the horizon. The OP's question does make sense. The Sun being up isn't actually a big problem, though, it's only a problem if it is very close to the Earth in the sky. --Tango (talk) 18:08, 19 March 2009 (UTC)

I'll take a shot at these:

1. First of all, what would be the length of such a mission? I hear people say that the trip there would take 3 months or so, but the entire trip would take much longer, wouldn't it? - yeah - it's partly the launch-window thing, partly that having spent 3 months getting there - and needing another 3 months to get back, it would be kinda silly to stay just a couple of days as we did on the moon. Plus, prolonged periods in zero G aren't good for you - and the guys will need time to recover some of their lost muscle and bone mass for the trip back home. This is also going to be a ruinously expensive trip - we won't be sending half a dozen manned missions there as we did to the moon.

• I'm having trouble even imagining how much food and fresh water you'd need to bring to stay alive that long (not to mention the psychological effects - those are all very serious concerns. The plan currently is two-fold. One is to send an unmanned vehicle to mars to manufacture water and (by electrolysis) oxygen and some hydrogen fuel for the return trip - using sunlight for energy, subterranean ice as a water source...whatever. When it has enough supplies built up - we send out our manned mission with enough fuel for a one-way trip - and only enough water and oxygen for the ride out there. We'd need to recycle (we already do that on the ISS for example) - and we'd need to grow our own food en-route using hydroponics and such like. It's not easy - and that's why we didn't do this LONG ago! When we get there - we land a short distance from the robotic mission's landing site - fill up on fuel, water oxygen for the stay - refill again for the trip home. Psychological concerns have been somewhat addressed. Plenty of people have been cooped up in the ISS and in MIR for a year and managed to keep it together that long. Being able to leave the spacecraft and wander out across Mars should make that easier - not harder.

2. Second, what about communications with Earth? - No problem. We've been communicating with the 'Spirit' and 'Opportunity' rovers non-stop for something like five years now! We can still send messages to (and get data back from) the clunky old Voyager probes that have completely left the solar system. This is really not a problem.

3. Third, what tangible benefits would a manned mission to Mars yield? - I have a problem with this too. There is value for sure in having LOTS of humans living their lives on Mars - we need a 'backup planet' in case something terrible happens to ours. For that reason only - we need to make a start on being there - and the first step is to get a small crew out there.

• No need to worry about some dude going ape-shit crazy and slaughtering the rest of the crew for one thing - again, it didn't happen with people cooped up in the TINY space of MIR over an entire year (although they certainly had their problems). I think once they get to Mars - they'll be too busy to worry.
• (presumably the robot would have a "become_self_aware = false" line in its code somewhere). -  :-) Indeed - Asimov's first law of robotics is a "must have" kind of thing...and no putting red LED's in it's fake eyesockets either...that's just not funny! Particularly avoid: "if ( become_self_aware == true ) eye_socket_LED_illumination_level = 1.0f ;"

SteveBaker (talk) 19:12, 19 March 2009 (UTC)

And extra-extra-specially avoid:

if ( become_self_aware = true ) eye_socket_LED_illumination_level = 1.0f ;

-- Speaker to Lampposts (talk) 03:01, 20 March 2009 (UTC)

It took me a while to work out what you were saying that (I didn't cheat and click the link!), but I laughed out loud when I got there - very good! --Tango (talk) 14:54, 20 March 2009 (UTC)

Strictly speaking, we haven't communicated with Spirit and Opportunity non-stop - there are short periods when they are out of contact due to the position of the Sun. It's only a couple of days a year, or so, though. The lack of real-time communication with anyone other than your crewmates might make life on Mars a little harder than life on MIR/ISS - the psychological issues certainly need to be dealt with, but I don't think any of them are deal-breakers. --Tango (talk) 14:54, 20 March 2009 (UTC)

To answer the OP's third question: Mars can be explored much faster with humans than with robots because robots are nowhere near as intelligent as a human. Consider this recent possible discovery of liquid water on Mars, for example. It's been months since the pictures were sent back, yet scientists still aren't sure whether what they're seeing is liquid water. If any human saw that substance, he could poke at it and figure out whether it's water within a few seconds.

Another example: Spirit and Opportunity, the two rovers exploring Mars, are constantly meeting obstacles, stopping, and asking Earth for directions. Just read this update archive. It took days for Spirit to get around a potato-sized rock. It's hard to imagine anything a human failing to navigate around anything smaller than a mountain.

So, why should robots not be made self-aware? I'd think conscious robots would be extremely helpful in exploring Mars, as they'd presumably allow the planet to be explored with on-the-spot decisions (as opposed to decisions made by Earth, which take a long time). --Bowlhover (talk) 00:57, 21 March 2009 (UTC)

"Mars can be explored much faster with humans than with robots because robots are nowhere near as intelligent as a human. " An opposing argument is that it is cheaper to send a robot, because we don't care if it never comes back. A "Hero Astronaut" must have a return capability, with multiple redundant everything. A robot just goes there and is abandoned when it quits working. If it crashes or falls in a hole, too bad, and we send another a bit later. It is far cheaper to send an analytical lab there than to send a Hero Astronaut to walk around for a bit and then bring rocks back. Plus, we avoid the Andromeda Strain scenario wherein pathogens wreak havoc back on Earth. Edison (talk) 02:15, 21 March 2009 (UTC)

Another way to look at is that we could probably send dozens of rovers, more quickly, and for less cost, than a human crew. Those rovers could stay functional on Mars for longer than a human, who would likely need to head home after a brief visit. StuRat (talk) 05:39, 24 March 2009 (UTC)

Research with Blood

What is the easiest way to overlay blood on to a FiCol or similiar medium before centrifugation? Currently you have to poor blood from one test tube to another prefilled with medium (ficol) 15-50 mL test tube. —Preceding unsigned comment added by 98.154.31.61 (talk) 07:36, 19 March 2009 (UTC)

I suggest that you start with a tube containing blood diluted 1:1 (to reduce loss of mononuclear cells at the interface) and underlaying with Ficoll. You need a very clean interface to get good separation. To achieve this, use a long pipette attached to a pipette-aide, load it with the desired amount of Ficoll for the blood volume and tube size you're using, insert through the blood to the bottom of the tube, then very slowly dispense the Ficoll, being careful to avoid ejecting a bubble of air! Spin with the brake off, of course. --Scray (talk) 11:07, 19 March 2009 (UTC)

Waterflow of the Amazon River

I am interested in knowing more about the force and speed of the waterflow/steady stream of the Amazon, i.e. close to the outlet but before the flow is divided by the "branches" of the delta. Perhaps this can be calculated from the daily amount of water going from the river into the sea, with the tide taken into account?

Does anyone have information about the speed of the flow out to sea? It would be an interesting addition to the page.

—Preceding unsigned comment added by 195.67.112.146 (talk) 10:17, 19 March 2009 (UTC)

On the Amazon river page, the information box notes that the "Discharge - average" at the mouth is 219,000 m³/s; I'll let you do the conversion, but you should get a little over 10¹³ L/day (a truly mind-boggling amount). My impression is that this takes into account tides, etc. The Drainage area section notes that this can increase almost 40% to 300,000 m³/s during the wet season. What is it you wanted to add? The Talk page might be a good place to discuss additions. --Scray (talk) 11:24, 19 March 2009 (UTC)

Using Scray's numbers, roughly 10¹³ L/day, divide by 24, then by 60 and then 60 again to get per second which gives us approx. 1.16 x 10^9 L/sec. Seeing that one liter of water is approximately one kilogram, we can assume 1.16 x 10^9 kg if the mass of the water.

Speed of the Amazon is approximately 3 miles per hour, which is 1.34 m/s^-1. Seeing as one liter of water weights approximately one kilogram, we can convert Scray's value of 10¹³ per day into 1.16 x 10⁹ kg of water flowing per second. Using F=ma, 1.16 x 10⁹ x 1.34 gives us 1.55 x 10⁹ N of force. I feel that's unusally high, but I'm not a good physicist so I'll let others rip that working out to shreds. —Cyclonenim (talk · contribs · email) 16:58, 19 March 2009 (UTC)

A liter of water has a mass of exactly one kilogram, by definition, not approximately, though there are obviously additives that will change the actual measured mass/weight. Matt Deres (talk) 17:06, 19 March 2009 (UTC)

I was just wondering how much suspended sediment load there would be in a litre of Amazon river water, so I did a back of the envelope calculation taken from some annual figures of discharge and sediment load (6300 km³ per year & 1200 x 10⁶ tonnes per year [4]), and came up with a mere 0.2 g of suspended sediment in each litre; enough to make it look a bit murky but not enough to seriously affect the approximation. Mikenorton (talk) 19:14, 19 March 2009 (UTC)

Wow, so there's 2.32 x 10⁵ kg of suspended sediment in the Amazon? That's a lot of sediment! —Cyclonenim (talk · contribs · email) 19:34, 19 March 2009 (UTC)

Just as an aside, the Amazon is recognised as the largest river in the world by volume, but is it true what I read that there is an underground "river" underneath the Nile that is six times bigger than the river on land? ~AH1^(TCU) 01:46, 20 March 2009 (UTC)

That would be the undercurrent of denial, right?  ;-) --Scray (talk) 10:44, 20 March 2009 (UTC)

Beneath the Nile there is an enormous canyon created by the drop in base level associated with the Messinian salinity crisis. That is now filled with silt, I don't know if there is likely to be any significant groundwater flow through this great pile of sediment (2400 m thick beneath Cairo) that could be compared to the surface flow. There is interaction between the Nile and aquifers in its banks in the Cairo area, both discharge and recharge,[5] but I'm not sure you would call any of that an underground river. Mikenorton (talk) 11:44, 20 March 2009 (UTC)

query

Practical methods of production of callus cultureVidya mandava (talk) 11:07, 19 March 2009 (UTC)

Web search for "callus culture" provides plenty of information. If you have a specific question, please state it clearly and I'm sure people here will respond with similar care. --Scray (talk) 12:48, 19 March 2009 (UTC)

Biochemical processes within crocodile...

how can crocodile stay under water so long time? what biochemical processes are within it when it's under water? —Preceding unsigned comment added by Beqa22era (talk • contribs) 11:11, 19 March 2009 (UTC)

1) They don't. Their nostrils stay above the waterline in their normal floating position, so they can breathe normally.

2) When they do go underwater, just being a reptile allows them to hold their breath much longer, since reptiles are cold-blooded. Warming the body requires a great deal of energy, and "burning" that energy requires oxygen. Therefore, the oxygen requirements for cold-blooded animals are far lower. StuRat (talk) 11:39, 19 March 2009 (UTC)

Cold-hearted orb that rules the night....

I'm under the impression that the center of the Moon is far cooler than the center of the Earth. This brings up some Q's:

1) What are those two temps ?

2) Why the diff ? Does it have anything to do with the Moon being tidally locked to Earth, but the Earth not being tidally locked to the Moon ?

3) Is there a formula which can predict the temp at the center of a planet or moon, based on it's mass and distance from the Sun ? (I'd include density, but that may also be somewhat dependent on the temperature). StuRat (talk) 11:35, 19 March 2009 (UTC)

Partial answer to part 1: Various sources for the earth's core temperature are listed here with 7000 c. being most prevalent, 10,000 c. here, and 9,000 here, so as you can see there's little agreement, which is unsurprising given that we have no direct measurements and all answers are currently based on extrapolation. By the way, are you a Moody Blues fan? (or were they quoting someone else when they used that line?)—70.19.64.161 (talk) 12:17, 19 March 2009 (UTC)

Yes, very good, it's from the Moody Blues Late Lament, immediately following Knights in White Satin (is that about the Ku Klux Klan ?). That quote seemed to match my Q rather well. StuRat (talk) 13:56, 19 March 2009 (UTC)

Actually it's "Nights in White Satin": a song which is from an LP "Days of Future Passed" which is about the events of days and nights. Wherever do you get KKK from??? I'm not sure 5 lads from Birmingham (England) would even have heard of the KKK in 1967! --TammyMoet (talk) 14:24, 19 March 2009 (UTC)

The redirect made me think my spelling was correct. I wish they had a different color for links which point to redirects, to avoid this problem. The KKK members fancy themselves to be feudal knights, and often wear white satin robes (and many would consider them to be "white satans", too). The Birth of a Nation poster demonstrates both aspects. StuRat (talk) 14:50, 19 March 2009 (UTC)

For (2), that's likely some part of it, but our structure of the Earth article suggests that the prime source of heat is left over from planetary contraction. Given that the Earth is on the order of 80 times more massive than the Moon, I expect that explains the discrepancy nicely. For a partial answer to (1), inner core puts it at approximately the temp of the sun's surface, 5800K. — Lomn 12:21, 19 March 2009 (UTC)

That value is actually for the outer core-inner core boundary, according to the source quoted, so probably significantly hotter at the centre. Mikenorton (talk) 12:45, 19 March 2009 (UTC)

This source [6] gives a temperature for the centre of the moon as 830°C (1003°K). It also suggests that this temperature means that the concentration of radiogenic isotopes is greater than within the earth. If it wasn't for this heat source both bodies would be a whole lot colder (or need to be much younger). Mikenorton (talk) 12:58, 19 March 2009 (UTC)

I had no idea it was that hot. That means there's some point under the surface which is always a good temp for people, doesn't it ? It would also mean that "lunarthermal" power might be possible. StuRat (talk) 14:14, 19 March 2009 (UTC)

I prefer the word 'selenethermal' power. :) Dauto (talk) 23:32, 19 March 2009 (UTC)

How about princessserenitythermal power ? StuRat (talk) 04:53, 22 March 2009 (UTC)

Might have to hold back on the lunarthermal energy, the quoted values for heatflow from the Apollo program are somewhat less than the average for the earth and the average is not enough to make geothermal energy a viable option (aside from heat pumps). As far as reaching a liveable temperature, I would guess just being below the direct influence of the diurnal temperature variation would be sufficient. Mikenorton (talk) 14:56, 19 March 2009 (UTC)

That and isnt the traditional method for geothermal energy involve large quantities of water to convert into steam? Something the moon lacks. 65.167.146.130 (talk) 15:24, 19 March 2009 (UTC)

I'd say that density has an effect on it too: Neptune's density and core temperature are both higher than Uranus', for example. ~AH1^(TCU) 17:29, 19 March 2009 (UTC)

Stents

Hi does anyone know why stents, e.g. those used to counteract constriction of the common bile duct; are mesh like in appearance? Why are solid lumps of metal not used instead? Is there any point in them having a mesh structure? Thanks. —Preceding unsigned comment added by 139.222.240.225 (talk) 11:41, 19 March 2009 (UTC)

I would guess the mesh stints are flexible and move with the tissue better. I think its also good to minimize the amount of foreign matter in any body. The mesh stints can also be compressed while they are being put in place and then allowed to expand to their working dimensions.--OMCV (talk) 12:12, 19 March 2009 (UTC)

One reason may be that the mesh tubes are somewhat flexible (as noted above), a second one would be that the gaps allow for the continuing function of the walls of the duct and prevent some atrophy of a small section of the relevant passage (coronary, urinary, etc). --Cookatoo.ergo.ZooM (talk) 12:16, 19 March 2009 (UTC)

Stents have to be cylindrical to allow normal flow through the vessel (or duct) where they are located. They are inserted using a catheter that has a balloon around which the stent is wrapped. The balloon is passed into the narrow section, inflated, and then deflated leaving the stent to maintain the enlarged diameter. If solid-walled, the balloon would have to actually stretch the metal. Instead, the balloon just bends the metal mesh stent to conform to the wall of the vessel/duct (the length of the stent decreases as the diameter increases). --Scray (talk) 12:41, 19 March 2009 (UTC)

Similar to tights/stockings, really - a mesh is a very stretchy structure. --Tango (talk) 13:45, 19 March 2009 (UTC)

Well thats cleared that up - thanks to all who helped. —Preceding unsigned comment added by 139.222.241.162 (talk) 20:50, 20 March 2009 (UTC)

Help Me! I am stuck on some issues about Evolution

Evolution does away with God. No God. I then worship myself, doing whatever I want owing to no one. Evolution does not happen around me. I have never seen a chicken turn into a dog. I frequently see gaps in evolution. “Dino dung contains grass”. About the dino bird: Why on earth does a dino turn into a bird. Why do anything when the universe is just going to go kaboom in a billion years. The Creation “myths” seem alright with me because I know Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years. The Bible is bullied. People use evolution for racist ideas. Evolution seems to allow racism. Compassion only came into existence because of chance. The Bible is also used to allow racism, but I read that we are to love every one as ourself. None of the: “I just evolved, no point in life, don't need to love coz love just evolved”. DNA does not grow on trees. My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it. [Year 11 student in Perth, Australia] —Preceding unsigned comment added by 60.230.212.29 (talk) 11:45, 19 March 2009 (UTC)

You have a lot of questions there, and it might help to organize them better, say as a numbered list, if you expect answers to all of them. Also, evolution says nothing about the existence of God, just that God isn't necessary for the step of one species evolving from another (although you could still argue that God controls mutations). God may still be used as the cause of the Big Bang, etc. God (or "the gods") used to be thought of as doing everything, from making day and night to the seasons, but we now know that is all just a consequence of the Earth's rotation and revolution. In another example, we now know that the variation in children in a family is due to random combinations of DNA in chromosomes. StuRat (talk) 12:04, 19 March 2009 (UTC)

Let me say that it's really poor logic to conclude that anything you haven't witnessed personally doesn't exist. Also note that this would apply to everything in the Bible, unless you're a lot older than you seem. :-) StuRat (talk) 12:27, 19 March 2009 (UTC)

As for gaps in evolution, they are relatively small, and closing all the time as we find more fossils. Gaps in the Bible are absolutely huge, on the other hand, and not getting any smaller. For example, how did we get from Adam and Eve to all mankind ? Was there a lot of incest (as opposed to a Lot of incest) ? StuRat (talk) 12:31, 19 March 2009 (UTC)

As for your "Why do anything when the universe is just going to go kaboom in a billion years" (it's actually many billions), the same is true in the Bible, only on the order of thousands of years, isn't it ? That nasty Armageddon bit in Revelations ? And in billions of years, who knows, perhaps we will be able to travel to parallel universes which aren't about to die. StuRat (talk) 12:21, 19 March 2009 (UTC)

You said "Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years". You seem to be confusing evolution with geology. There are some geological formations which are formed quickly, yes. There are others which take millions or even billions of years to form. Plate tectonics is a good example of the later, where the continents all used to fit together. In some cases, it's obvious just by looking at them that they once did. The rate at which they are moving tells us it took many millions of years for them to get where they are now. Rates of radioactive decay also tell us that the oldest rocks on the Earth are around 4.3 billion years old. StuRat (talk) 12:51, 19 March 2009 (UTC)

To take on another of your Q's, let's talk about why a dinosaur might evolve into a bird. First, feathers are useful for flight, but also provide for good insulation. There are many flightless birds, like penguins, which use them for insulation. Next, flaps of skin can develop on arms to allow for longer jumps from tree to tree or on the ground. This has happened in flying squirrels, too. Then, once these basic items are in place, even a small improvement can allow for longer jumps or glides, both of which are helpful for survival. This eventually leads to all the birds. StuRat (talk) 12:14, 19 March 2009 (UTC)

If you pray to God for wings, and they sprout out and you fly away, then, by all means, believe in God. If that actually happens, I may even join you in your beliefs. StuRat (talk) 12:46, 19 March 2009 (UTC)

Neither evolution nor the Bible can be used to define a moral code. Evolution says nothing about morality. The Bible says a great deal; so much, in fact, that it has parts that can support any moral code you want, from slavery, genocide, and hate crimes against homosexuals, to the oppression of women. So, in either case, you come up with your moral code on your own, and only use evolution or the Bible to justify what you already believe. StuRat (talk) 12:42, 19 March 2009 (UTC)

Evolution does away with the literal interpretation of the bible god; it does away with the YEC's god, but evolution has little to say to millions who have compartmentalized enough to conform their mythos to the real world. Inductive logic is what does away with god. But based on your post, I'm wasting my breath. You need to take evolution in baby steps. Start with biology 101 and move progressively. I doubt that will happen but the problem is that you're so lost in the fundamentals, your knowledge of the subject so narrow, that you can actually say something like "I have never seen a chicken turn into a dog." By saying this you show that you have no understanding of evolution at all. Not even the tiniest scintilla, but have some one or two sentence idea of "things turning into other things for mysterious reasons" that is called evolution. The poster above is trying to be helpful but he's skipping the part where we sit down with you for months and months teaching you the basics so you have the slightest understanding to put his post in context.—70.19.64.161 (talk) 12:30, 19 March 2009 (UTC)

Have a look at Introduction to evolution and let us know if you have more questions. Btw, if you asked your teacher how you could "gain more DNA to grow wings", he/she probably thought you were joking. Zain Ebrahim (talk) 12:51, 19 March 2009 (UTC)

If you "know" that volcanos and floods can cause things that scientists say take millions of years than you're mistaken. Perhaps you're thinking of a common claim that the Grand Canyon could have been created during the Great Flood. This doesn't even stand up to casual examination by a layman. A massive amount of water unleashed at once would cut a wide, shallow swath, not a sharp deep one like a canyon. (And of course, once it's completely covered, even this effect would slow greatly.) You can verify this in your backyard with a large tub of water and a garden hose.

"My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it." He is right. The only way you -personally- will will gain additional DNA is divine intervention. Evolution is caused by children having slightly different DNA than their parents. Once you're born you're stuck with whatever DNA you've already got.

"Why do anything when the universe is just going to go kaboom in a billion years." Frankly, I've always thought the answer to this is : "To see how much cool stuff we can do before then." APL (talk) 13:24, 19 March 2009 (UTC)

And finally, just for the record, DNA does grow on trees! --Sean 13:45, 19 March 2009 (UTC)

In the form of fruit, no doubt. As for sprouting wings, eventually scientists may be able to use a virus to insert genes (to grow wings) into our DNA. However, the wings we would grow would only be decorative. To make a human capable of flight would require a total redesign of our entire body, including tiny legs. StuRat (talk) 13:54, 19 March 2009 (UTC)

You say on the first line without God you would do what you want owing to no-one. Have you asked yourself if there really is anything much different you would actually do without God looking over your shoulder? Or are you thinking that other people would behave any differently? Dmcq (talk) 14:19, 19 March 2009 (UTC)

On the subject of sprouting wings. There is a slight problem with the fact that the Angel type of construction basically adds another set of limbs when compared to ordinary things with wings like birds or bats. You'd not only need divine intervention to get wings, you'd also need a constant miracle to move them or would have to add a rather unsightly hump to your ordinary back.

Artist pictures don't show any muscles needed to move the wings. (Not to mention the joint that connects them to the body). I assume they are just a decorative appendage and your divine entity would actually provide for Levitation. 76.97.245.5 (talk) 14:57, 19 March 2009 (UTC)

Oh my - what a lot of questions. Well, now that you've asked so many - you are honor bound to slowly read through ALL of my carefully thought-out answers! No cheating and skipping the ones you don't agree with!

• Evolution does away with God. No God. - Not precisely. Evolution does away with the need to use god or gods to explain how we came to be. You are still at liberty to assume that god(s) made the world in one night on September 12th 1962 - and just made it all "look" like there was evolution. It's a pretty crazy thing to believe - but if you've gotta have a god to sleep at nights - there you go.
• I then worship myself, doing whatever I want owing to no one. - Well, you COULD - but you live as a part of society that imposes rules in order to make life bearable - and if you do literally "what you want" - then the odds are good that other people will get pissed about it and you'll find that you are physically unable to continue doing what you want. Societal pressures to behave according to the norms are considerably more effective than religious pressures simply because the punishment or restraint is immediate and vastly more certain. I'm fond of pointing out that the Bible is the most shop-lifted book in the USA. Clearly people who are going into bookstores and stealing them aren't afraid of divine retribution.
• Evolution does not happen around me. I have never seen a chicken turn into a dog. - No, but if you lived in New York, you'd have seen rats turn into Warfarin-resistant rats that thrive on eating rat poison. If you worked in a hospital, you'd have seen tuberculosis-causing-bacteria turn into tuberculosis-causing-bacteria-that-you-can't-kill-with-antibiotics. The process is relatively slow. However - (for example) humans appear to have evolved to become lactose-tolerant over a space of a few thousand years - and the process isn't complete yet...that's truly evolution in action. There are MANY cases where evolution can be observed happening for real right in front of your eyes in a test-tube. But to change a chicken into a dog might require millions of years of evolution - and that's something you obviously can't see happening before your very eyes. Just because a process takes a long time isn't a reason to assume that it's not true. It took a long time for a relatively small river to carve out the Grand Canyon...but we don't go around denying that this is how it happened.
• I frequently see gaps in evolution. - no you don't. You frequently hear like-minded "intelligent design" idiots CLAIMING that there are gaps in evolution. You've never personally spotted one. In fact, science is still plugging holes - finding fossils isn't something you can do "on demand". If you don't happen to have a fossil that shows something halfway between a smooth-skinned fish and one with scales doesn't mean that there is a horrible "gap" that completely blows away the theory - it simply means that nobody has yet found a fossil of that particular animal. Because we HAVE found long chains of very similar animal fossils that DO show continuous, gradual, gapless change from one species to another - we KNOW for 100% certain that those particular species evolved. And with every 'chain' of fossils we find, the gaps get smaller and less frequent - but to expect to have complete evidence for the pathway from every single creature to every single other creature is stupid. There comes a point (and we're WELL past it) where the evidence is simply overwhelming and the gaps are perfectly explicable. "Absence of evidence is not evidence of absence."
• About the dino bird: Why on earth does a dino turn into a bird. - Because of some sort of evolutionary pressure. If running along the ground is too dangerous because of predators (say) then maybe a small genetic change allows the creature to have the musculature to climb trees. That creature does better than the earth-bound dinosaurs - so it survives when the ground-based ones are all eaten by predators. However, the ones in the trees still have to climb down out of one tree and up into the next - so they are vulnerable still. If one baby tree-dino happens by luck to have genetically stronger legs and can jump from a tree to another nearby - it'll spend less time on the ground and it (and it's offspring) will thrive while the ones that have to climb down don't. Now, they only have to go to the ground to get from one clump of trees to the next. But if they evolve a flap of skin or feathers and lighter weight bones - they'll be able to glide between trees that are still further apart. Then they may evolve powerful muscles to allow them to flap a bit. Before you know it (and over half a million years) you have birds. Then something happens to all of the predators (like maybe a meteorite kills them all) and the birds have no more predators on the ground - so evolving to be more capable on the ground so you can eat stuff you only find down there - makes sense. Now you have flightless birds like chickens. When the predatory mammals come back - they evolve into ostritches that can kick the hell out of a predator...and so on and so on.
• Why do anything when the universe is just going to go kaboom in a billion years. - Indeed, why? Guess what? It's evolution again. If a bunch of humans got it into their silly heads that they should just lie in bed until they die because life is pointless - then they'll fail to pass their crappy genetic makeup onto any children - so only the kids of the people who suck it up and try to make something of themselves will survive into succeeding generations. Before you know it - we've evolved a powerful drive to survive - to have children and to look after them. Hence we are genetically PROGRAMMED not to shrug our shoulders and give up on the world.
• The Creation “myths” seem alright with me because I know Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years. - Bullshit. Please explain how a volcano or a flood turns a dinosaur into a chicken? I explained how evolution can do it. What you are REALLY saying is that this is all too hard for your tiny little brain and you're too stupid to think for yourself so you'd rather be spoon-fed a bunch of nonsense than to actually examine how the universe works - look at the evidence - take your sorry ass down to the nearest decent natural history museum and ASK one of the curators if they can show you some fossil sequences to help you to understand. Nope - it's better for you to have some idiot in a silly costume get up there on a sunday morning and tell you that it all happened by magic. Well, good luck with that!
• The Bible is bullied. - The Bible is WRONG. I've actually read the Bible - not just a verse here and there as instructed by some Sunday school teacher. I started at page one and read it all the way through - like a real book. It's CRAP! It's self-contradictory, inconsistent, flat out unbelievable. It starts off with this rabid lunatic of a god who does the nastiest things imaginable for the smallest reason - to someone who is supposed to be kind and caring and it's all rainbows and unicorns. You actually have to read the book with open eyes to see what a pile of steaming crap it really is.
• People use evolution for racist ideas. Evolution seems to allow racism. - I don't understand why you'd say that. People have certainly used the Bible to promote racist ideas. Just take a look at the KluKluxKlan nut-jobs! They are passionately religious - and equally passionately racist - and they justify every word of their racist nonsense from the Bible.
• Compassion only came into existence because of chance. - Actually, there is evidence that compassion and being nice to people and stuff like that is evolved too.
• The Bible is also used to allow racism, but I read that we are to love every one as ourself. - And I read (in the Roman Catholic/Lutheran bible - the first of the 10 commandments - that if you worship an idol - your children, grandchildren, greatgrandchildren and great-great-grandchildren will be punished. Sheesh! So if my great-great-grandfather was worshipping idols - I get punished for it!?! Nice god! The bible also says that if your son swears at you - you should kill him. (Although you aren't actually ALLOWED to kill him...hmmm tricky). Really - it doesn't stand up to close examination.
• None of the: “I just evolved, no point in life, don't need to love coz love just evolved”. - Nobody who believes evolution to be true says that. We have EVOLVED to have point to our lives. Heck - I'm an out and out atheist - I love life. I had fun as a kid learning stuff - I loved - I married (although a civil contract would have been OK by me). I have a son - we enjoyed bringing him up right - teaching him moral values - things that make society run well "Don't kill people - don't steal things - but go ahead and covet your neighbours ass - I don't give a damn about that". We've EVOLVED those concerns because we're a tribal society. Getting on with a village of people is how we're programmed to be. Passing our DNA onto the next generation is something we're powerfully driven to do. Anyone who didn't have those drives - passed on in their DNA from their parents - would not have children of their own - their DNA would not get passed on. So only the people with genes that give them the drive to have children get to pass their DNA on...so after not too many generations, pretty much everyone wants kids - most people like raising them. It's evolution that does that.
• DNA does not grow on trees. - yes it does! :-)
• My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it. - your science teacher is 100% correct in that! Certainly you can't "gain more DNA" by any known scientific means - you're absolutely stuck with what you were born with. If/when you pass your (and your partner's) DNA onto your children, their DNA will be a little bit different - and the DNA of THEIR children will be different still. If there is an evolutionary pressure for humans to sprout wings and fly - then perhaps over tens of thousands of generations, that MIGHT happen. Evolution is a slow process. So - if there is a god - you could certainly pray for DNA to grow wings with...and by all means try that. Pray your darnest...plead with God for those wings. Do you REALLY think he'll give them to you? I don't.

SteveBaker (talk) 18:53, 19 March 2009 (UTC)

Steve, the refdesk is not a soapbox. —Preceding unsigned comment added by 65.167.146.130 (talk) 19:10, 19 March 2009 (UTC)

Soapboxing refers to a situation where someone pretends to ask or answer a question, but is actually just propagating his agenda (or, in some cases, doesn't even bother with the question part at all). Clearly, Steve is answering the original poster's specific questions, and doing a pretty good job of it, too. Yes, absolutely, you can also tell that Steve has opinions about the matter at hand, but he's not expressing them instead of answering the questions. -- Captain Disdain (talk) 19:30, 19 March 2009 (UTC)

I actually don't see a question from the OP, merely a long list of statements.65.167.146.130 (talk) 19:57, 19 March 2009 (UTC)

He may not be soapboxing, but Steve, please dont bite. Livewireo (talk) 20:07, 19 March 2009 (UTC)

As an aside, I will worship any god, demon, or other deity that gives me the capacity for free flight without any technological support. (I would prefer a pair of wings, but Superman-style flight would also have its advantages.) It goes without saying that I expect this ability up front before I start with the worshiping. I'm an atheist, But I can be bought. :-) APL (talk) 21:19, 19 March 2009 (UTC)

I'll join you in that religion, but if it's going to be superman-style flying someone had better give me a cape - I'd look stupid without one! --Tango (talk) 23:08, 19 March 2009 (UTC)

Could I take the free flying stuff - then weasel out of the whole worshipping thing afterwards? SteveBaker (talk) 23:34, 19 March 2009 (UTC)

Might be unwise. The Lord giveth, and the Lord taketh away - and if He taketh away thy flying at 25,000 feet, thou art screwed. - Eron^Talk 23:36, 19 March 2009 (UTC)

That's why sensible gods don't give all their rules in written form - it makes it too easy to find loopholes. If you keep the rules nice and vague you can make them fit the situation however you need. --Tango (talk) 23:39, 19 March 2009 (UTC)

The Bible is WRONG Hm Steve, what about the very first chapters of the Bible (and some other chapters) being just symbolic? One should read the Bible for it's moral teaching, it's not intended to be used as a science book. Too bad some zealots try to regard it (and try to enforce it) still as a science book, destroying the main concept behind it... and by doing so they are making religion to look ridiculous too. —Preceding unsigned comment added by 79.116.91.3 (talk) 01:19, 20 March 2009 (UTC)

You haven't read it have you? I tell you - start from page 1 and read to the last page...it's an education. The old testament is NUTS - yeah, yeah - it's all symbolic. So why the heck does it matter if it's just a work of fiction? I don't think the stories surrounding the ten commandments are intended to be symbolic. That bit is really pure slapstick - the guy spends an age up there chatting with god - chiseling the words into literal stone tablets - and when he gets back he drops them (oopsie!) and the break so and has to go back up to god and get another set...but this time, God has obviously lost his train of thought because the second set have completely different rules...this combined with a God who really needs to switch to decaf. SteveBaker (talk) 04:03, 20 March 2009 (UTC)

Symbolic or not, you can't just cherry-pick the parts that sound nice -- bring up the cuddly "let's all just get along" bits as proof of how wonderful moral guidance the Bible provides and ignore the crazy-ass "the hero of the story murders 200 people for their foreskins to prove his righteousness and get some poontang" bits.

Oops, that was me. I forgot to sign. -- Captain Disdain (talk) 12:08, 20 March 2009 (UTC)

Let's just play the Devil's advocate again :) What if the moral is contained in the New Testament, and the old one is just for showing... well, how crazy it was before it/would be without it. --79.116.89.247 (talk) 23:46, 22 March 2009 (UTC)

But that is simply not what it says. The Old Testament is clearly full of commandments from God. It was also written hundreds of years before the New Testament, so clearly wasn't intended to be compared to it. --Tango (talk) 00:00, 23 March 2009 (UTC)

If the moral is contained in the New Testament, then you're cherry-picking. You're making a judgment call on what parts to glorify and what parts to ignore as insignificant. The problem with that is that if it's up to you to figure out what's right, then you're by definition following your own morality, not some great ancient divine wisdom. You can't have it both ways. (Anyway, the New Testament isn't that much better. It still advocates slavery and doesn't exactly say a lot of nice things about the value of women, for example.) -- Captain Disdain (talk) 06:20, 23 March 2009 (UTC)

Moral teachings as in "The most important thing for anyone to do is to cater to the megalomanic whims of their creator."? No thanks. --Tango (talk) 14:48, 20 March 2009 (UTC)

Just by the way, I can always, always tell when it's SteveBaker who is posting. Your style of writing, it's etched into my memory. Especially with allcaps for EMPHASIS (no pun intended). ~AH1^(TCU) 01:39, 20 March 2009 (UTC)

Never mind the writing style (which is very distinctive, I agree) - you can tell from the length! --Tango (talk) 14:45, 20 March 2009 (UTC)

SteveBaker is not the only one who writes LONG arguments, replies, and questions, you know. :-) ~AH1^(TCU) 17:24, 21 March 2009 (UTC)

A chicken turned into a dog? Here you go.[7] --JGGardiner (talk) 02:46, 20 March 2009 (UTC)

Ah - and I was thinking [8]. SteveBaker (talk) 03:51, 20 March 2009 (UTC)

Evolution does away with God. I know of no serious student of evolution who would postulate such a thing. In fact, evolution ignores God, simply because one is science and the other religion. Or, if you insist on mixing the two, then simply acknowledge that there is nothing at all about evolution that is not compatible with a God. What it is incompatible with is creationism. Very different, unless you're a religious extremist. DOR (HK) (talk) 04:35, 23 March 2009 (UTC)

'I also have read the bible several times.'Some of the old testament reads like health suggestions.' Such as not eating pork.with no refrigeration and not knowing about food poisoning or parasites from uncooked or undercooked food, eating the meat of a scavenger(pig) could be deadly (Gods ultimate revenge)also, marrige would be a way to make the survival of children more likely. With multiple wives because of the high mortality during birth.etc. etc. etc. resource allocation for the in group, and damnation for the outgroup. Furthermore, the origonal poster does not take non Judeo/christina religions into accountHinduism, is older, and creationism according to the Rigveda, only vaguely says"there was nothing,then there was"Crazybearr (talk) 07:23, 23 March 2009 (UTC)

Wow, I have a bad day at school, go hiking for the weekend and come back and ... wow! Thank you to all the people who have contributed to this section, you are the people who make Wikipedia what it is. I have read through all your writing and even went so far as to observe other contributions made by every user. I am impressed. I will address Steve first since he answered me the most. Year 11 Student Perth, Western Australia 60.230.212.29 (talk) 09:03, 23 March 2009 (UTC)

Dear Steve, I studied your answers concerning evolution. However I cannot agree with you for most of it, and nor can my wise, and enjoyable, science teacher.

• Their would of being a lot of what you call incest when there was only a few people on the Earth. But back then it was not considered bad because their was no side effects, with perfect genes there was no problem medically.

• 20 years ago people scoffed at the Hittite civilisation that the Bible describes. Look it up and you will find that they are as real as the brain in your head.

• I vote the the page named Introduction of Evolution should be changed to Introduction of Specialization. Even so, the evolution page is quite confusing.

• Sorry for confusing you on my Volcanoes and Flood thing. What I meant to say is: “Volcanoes and floods can create and destroy what you believe to have taken millions of years?” Your are not telling me that radioactive decay can actually correctly tell me the age of a rock. I have sand and plants in my garden. If, say, I decide to test your experiment in my garden, with unlimited and copious amounts of water, it would go like this. Firstly the plants will be uprooted because the top soil is being washed away. The plants will still survive in the water, almost the same thing as hydroponics. Then the rest of the soil will wash away, causing a massive hole in my garden, likely a few other gardens and houses as well and a large river. A lot of water has been consumed. I am now using a massive hose pouring thousands of litres on my former garden. The water starts to erode the bedrock and has turned into a flood. A canyon, not half the size of your impressive Grand Canyon, has been formed.

• Show me pictures of the in betweens that Evolutionists claim to have existed and did actually exist. Your description of the Dinosaur turning into a bird made sense. But show me some pictures of these dino-gliders. I am interested. But you can also tell me how something as complex as the human eye evolved, just like you told me about the dinosaur evolution. Do not worry about being to scientific for me.

• Evolution says to God “We do not need you to explain how we came into existence” Precisely does away with God.

• About your statement involving the fact that the Bible is the most stolen book in the world. Well, think about this medicine is stolen with out thought that it is wrong, they need to save themselves or someone else from sickness.

• Hitler, Lenon, and Darwin are all people who have used evolution as an excuse for racist ideas. Darwin wanted Australian Aboriginals skinned and sent to him so he could study what he thought mistakenly thought of as a missing link. Hitler thought that his exterminations of Jews and his Master Race breeding program were just helping evolution go faster. Lennon authorised an experiment on African people and monkeys so he could create a half monkey half human slave army because monkeys are “related” to us, and therefore might just be able to breed with us. African people, according to the evolutionary idea are lower on the evolved scale.

• My statement concerning DNA growing on trees was small and was taken light-heartedly. DNA can be copied, mistakenly copied, lost (As in the case of your New York rats and bacteria, which is unfortunate to hear about.), but NEVER found, created or gained. Imagine a computer program, it had to be PROGRAMMED, right? This particular one is programed to copy itself. It is not on a perfect computer so data is lost and corrupted when it copies itself again and again. Sometimes those corruptions and lost data are good for it because the computer is always changing. How can something as complex as even a computer program evolve, how did it get there gradually? It could not.

• Coveting my neighbours ass is disrespecting her. I do hope your child is not disrespectful, just like you were to me. Calling my friends stupid, my religion crap and putting down what I believe in. But I will not hold that against you or Charles Darwin.

• If you believe the Bible, yet say that some of it is wrong, then, how can you believe in the Bible? If the Bible just contained people that were all cherry then would the Bible still be believable. The Bible contains a whole lot of information about David, second king of Israel, not all of it is good, he was not perfect, but the Bible is.

• In telling me that I am just PROGRAMED to live, that evolving and procreation is my only objective, that compassion and being nice to people just evolved, and that I can make up any moral code I like, then you have given me an excuse to commit suicide. But fortunately I have no desire to do so. Being a Christian not only helps me sleep at night but gives me a true purpose, not just something that has evolved and will evolve again. I can see a rainbow and know who to thank. I know that God loves me and made me special, just like he did for you. God would rather you believe in Him because you LOVE Him, not coz of fear or coz He can give you wings.

• Evolutionist - nothing to lose if there is no God
• Christian - nothing to lose if there is no God
• Evolutionist - eternity to lose if there is a God
• Christian - eternity to gain if there is a God

Then can you please show a better answer to why I should continue living. If I believed in evolution that is. Year 11 Student Perth, Western Australia 60.230.212.29 (talk) 09:03, 23 March 2009 (UTC)

I usually refrain from answering questions about evolution because the discussions never seem productive. However, there are several egregious comments that need to be addressed here:

• "African people, according to the evolutionary idea are lower on the evolved scale" -- This is an utter misrepresentation of evolution, and no honest person who truly understands the underpinnings of evolution would say such a thing. This would be like you saying that your 2nd cousins are "lower" on the "evolved scale" (whatever that is) than you are. Where on earth did you get the idea that evolution somehow ascribes a "higher" or "lower" degree of "evolved"-ness? This is utter nonsense.
• "...you can also tell me how something as complex as the human eye evolved" -- This is a common argument by proponents of "irreducible complexity" as some sort of "proof" that evolution does not occur. It may be true that we don't have a complete explanation for every single step in the process (yet), but it is pretty self-evident if you start to actually think about the problem that evolution of the eye is no different than any other part of the body. Others have already addressed these examples in great detail. Read the article on irreducible complexity. Understand what is being argued. There is no "proof" to be offered in simply stating that something is "too complicated to understand". It is lazy, non-scientific nonsense.
• "In telling me that I am just PROGRAMED to live, that evolving and procreation is my only objective, that compassion and being nice to people just evolved, and that I can make up any moral code I like, then you have given me an excuse to commit suicide." - this is a very bizarre interpretation of what evolution teaches us about life. Why do you use the example of suicide? Evolution doesn't give you an "excuse" to do something. It just explains how natural selection might act over millions of years to shape the behaviors exhibited in a species. We have eons of evolutionary history that selected for adaptive features, including fear, aggression, lust, greed, etc. etc. etc., yet our brains have also evolved over millions of years to excel at problem solving and therefore logic, and by logic human societies can arrive at reasonable standards of behavior that allow all of us to thrive and co-exist despite our most base instincts, therefore improving everyone's ability to pass on their genes. That some members of society do not comply with these standards of behavior, and cheat others for their own gain, is part of the evolutionary process as well (and not always rewarded over the long-term). That suicide exists is also part of the evolutionary process. If you know anything about cell biology you will recognize that there are well-regulated programs for cells to commit suicide. This process is fundamental to developmental biology and actually prevents cells from becoming cancer if they are malfunctioning -- cell suicide is therefore quite adaptive at the level of the whole organism. At a higher level, I would argue that evolution has endowed our species with a great aversion to suicide (otherwise we'd no longer exist) and that only under extreme circumstances do people consider this option. How does this conflict with evolution?

Alas, I have spent too much time responding and I fear that I may have been feeding the trolls. You will either spend time using your brain to consider these points, or you will simply be lazy and accept what you are told to believe. Life is yours to do with what you will. --- Medical geneticist (talk) 15:19, 23 March 2009 (UTC)

My pet name for the eye thing is argument from lack of imagination. —Tamfang (talk) 00:17, 24 March 2009 (UTC)

Student:

• About incest, what's your point?
• 20 years ago people scoffed at the Hittite civilisation .... Did your preacher say who scoffed? I have here a dictionary published in 1950 – yup, a rather long entry about the Hittites, their history, their ethnic affinities, and a mention of the decipherment of their language.
• You are not telling me that radioactive decay can actually correctly tell me the age of a rock. Yes, that's what (whoever) is telling you. Would you like to know how?
• Show me pictures of the in betweens that Evolutionists claim to have existed and did actually exist. Yah, so you can demand fossils between those and their neighbors? Show me a picture of the missing link between you and your mother.
• Evolution says to God “We do not need you to explain how we came into existence” Precisely does away with God. Only monotheists, it seems to me, are so hung up on creation. Polytheists have their creator-gods, but the creator usually isn't the most important one in the pantheon. Does evolution do away with their other gods too?
• Hitler, Lenin, and Darwin are all people who have used evolution as an excuse for racist ideas, bla bla bla. Can you point to any belief of any kind – religious, scientific, political, aesthetic – so pure that no wicked or misguided person ever adhered to some version of it?
• Imagine a computer program, it had to be PROGRAMMED, right? ... How can something as complex as even a computer program evolve, how did it get there gradually? It could not. You might find genetic programming interesting.
• I do hope your child is not disrespectful, just like you were to me. Calling my friends stupid, my religion crap and putting down what I believe in. Why should anyone be more respectful to your religion than you are to science?
• Then can you please show a better answer to why I should continue living. If I believed in evolution that is. Well, I continue living because I haven't seen all the beauty that I might see – or make.

—Tamfang (talk) 00:17, 24 March 2009 (UTC)

Technically, I should put this on Steve Baker's talk page but I can't figure out how.

Anyway, I enjoy Steve's responses and find them most informative. HOWEVER, his attitude toward the original poster was rude and condesending. I found it hard to focus on his arguements when his disrespect was so blatant. Steve: you owe the guy an apology. I guess you must have had a bad day.

Soami Oil?

I was at a trendy restaurant yesterday and they served a salad dressing made of balsamic vinegar and "Soami Oil". Surprisingly, no one could tell me what Soami Oil is. And there is no entry for it on Wikipedia. Any idea what it is? And is it even legal to serve a substance that no one can define? --67.66.110.148 (talk) 15:15, 19 March 2009 (UTC)

Just a wild guess, but there is Radha Soami Satsang Beas. It might be the newest fad, sort of Ayurveda used to be "in" and every marketing department tried to get it on their label.76.97.245.5 (talk) 15:38, 19 March 2009 (UTC)

Another very long shot, there's a company in Pune, India called 'Swami Oil Industries', that appears to make edible oils. Mikenorton (talk)

Laser safety

Is there something wrong with the graph at the start of Laser safety#Maximum permissible exposure? As I am interpreting it, the longer that you are exposed for, the higher the dose you are allowed to receive. That seems completely backwards. The second graph looks much more sensible. Should I just delete the first one? -- SGBailey (talk) 15:57, 19 March 2009 (UTC)

I haven't checked to see if it agrees with the source, but it seems to make sense. It's a graph of total energy absorbed (per square centimetre of eye) against time, so it's saying that the more total energy you absorb, the more time this dose has to be spread out over for it to be safe. Algebraist 16:14, 19 March 2009 (UTC)

Indeed. The difference between the two graphs is that the first is talking about energy density (J/cm²) and the second power density (W/cm²). The same amount of energy over a longer time is less dangerous because it corresponds to lower power. The same power over a longer time is more dangerous because it corresponds to more energy. --Tango (talk) 16:23, 19 March 2009 (UTC)

Ahh. OK. Thanks -- SGBailey (talk) 17:03, 19 March 2009 (UTC)

String theory

I've often heard that the mathematics behind string theory is really, really, really complex and that few can interpret the equations, let alone understand it. Could anyone provide an example of where I can see this stuff? I don't intend to try and understand it, I'm just curious to see how complicated we're talking here. —Cyclonenim (talk · contribs · email) 17:46, 19 March 2009 (UTC)

You can read some of it in this Google Books entry: [9] --Sean 17:57, 19 March 2009 (UTC)

What's that smell?

Hi. Recently on the non-residential sub-urban streets, especially those with lots of large trucks and side-road sand, I've noticed a particular strong and intermittent smell. It smells rather like three parts glue, two parts rubber, one part latex, one part chlorine, one part automobile exhaust, half a part paint, half a part sand and asphalt, half a part vinegar, a quarter part garbage, and a quarter part gasoline, co-mingled together. Sorry about my confusing decription, but I find it easiest to compare unidentified olfaction to other smells, and idea what it is or what causes it? Thanks. ~AH1^(TCU) 17:54, 19 March 2009 (UTC)

Where do you live?--Shantavira|^{feed me} 18:13, 19 March 2009 (UTC)

In S. Ontario, in the GTA. Does that help? ~AH1^(TCU) 18:30, 19 March 2009 (UTC)

It could be the asphalt they use to plug potholes. Is there a lot of black patches on the road that look like shiney black glue mixed with rocks? Livewireo (talk) 19:51, 19 March 2009 (UTC)

It may not be entirely out of the realm of possibility that you are smelling exactly what you have described depending on the surroundings. Truck exhaust, asphalt, garbage haulers, and any typical manufacturing facility (if there are any close by) can all be adding to the mix. cheers, 10draftsdeep (talk) 20:27, 19 March 2009 (UTC)

Here in North Carolina, lots of trees are in bloom right now, and many, like the Dogwood and Bradford pear trees in my neigboorhood have a rather pungent smell. It reminds me of methylamine sorts of smells (mildly like rotting fish), but lots of blossoming trees do give off odors that many people find unpleasant, like this one. Or it could just be all the stuff noted above. --Jayron32.talk.contribs 00:02, 20 March 2009 (UTC)

Are you talking gravel roads or paved? And what's your current thaw state? It could be patch asphalt (per Livewireo, you will see the patches), it could just be a winter's worth of crap melting and starting to rot/vapourize. And they may be putting non-clumping agents in the sand spread all winter too. I always found in Ontario that you could call up the local Works Department and they would be happy to answer questions and/or go check it out. Franamax (talk) 21:36, 20 March 2009 (UTC)

Pharmacological naming convention

I was wondering if there was any convention/rule/guideline for naming new medicine? I see there is a nomenclature for enzymes. Is there anything similar for drugs, such as anesthetics, etc.? --BorgQueen (talk) 18:38, 19 March 2009 (UTC)

Check out International Nonproprietary Name for the various systems available. --Sean 19:50, 19 March 2009 (UTC)

sinus operation......

My friend is suffering frm sinus infecion.....he drinks a lot of cold drinks..but at d moment he is suffering frm hi fever nd head ache. he consulted a doc. nd he said he has got cough depostied in his head. the doc. has given him medications. and said if these dont work....he needs an operation. i m a bit scared .is it something serious or is it ok....????????? pls suggest me wid something......... —Preceding unsigned comment added by Sweetgirl290608 (talk • contribs) 18:39, 19 March 2009 (UTC)

We are not medical professionals here and we can't give medical advice regarding how serious your friend's case may or may not be. For general information about sinus infections, you should read the article on Sinusitis. - Eron^Talk 18:45, 19 March 2009 (UTC)

Specifically, see here. We cannot offer you anything more than this, please tell your friend to see a doctor, and if you're interested, ask to go with him too. —Cyclonenim (talk · contribs · email) 18:46, 19 March 2009 (UTC)

Focalin shortage?

I've been trying to get a prescription of focalin refilled for about three weeks. They pharmacies say they haven't been able to get it and no one else has either. I asked if it had been recalled and they said no. Is there a shortage? Did they quit making it? Why aren't they able to get it?

I tried to find out who makes Focalin so I could ask them, but I could not find it. Bubba73 (talk), 18:48, 19 March 2009 (UTC)

I don't know the answer to your main question, but the first line of our focalin article says that this company produces it. —Cyclonenim (talk · contribs · email) 19:32, 19 March 2009 (UTC)

Also this company according to our Dexmethylphenidate article. Mikenorton (talk) 19:48, 19 March 2009 (UTC)

You should ask your doctor for help. S/he probably has samples of the drug that can tide you over until you can get a supply, and also contacts in the drug industry who will be very motivated to get you back on their product. You can also legitimately order scheduled drugs online after doing some paperwork. --Sean 19:42, 19 March 2009 (UTC)

I did call them today, they are supposed to get back to me. Sorry I missed the manufacturer in the article. Bubba73 (talk), 21:14, 19 March 2009 (UTC)

I couldn't find a pharmacy that had the medication, but the doctor found one. Bubba73 (talk), 16:38, 20 March 2009 (UTC)

doors

I had always assumed the huge old wooden doors with the rusty metal hinges were made of oak and iron, but I recently discovered these two materials don't work very well together. What actually happens if they are put together, and what do people use instead? 148.197.114.165 (talk) 21:16, 19 March 2009 (UTC)

Brass is a possibility. Wrought iron surface is different from cast iron. Annealing doesn't mention it, but this article does [10]. Not sure whether that would affect how it interacts with oak. Since oak was used for tanning presumably before it was used for doors, people probably knew about it's properties. AFAIK oak was often soaked and dried before it was used in construction. They also used pitch as surface treatment. My money would be on the Tannins in the oak wood eating your iron. Some of them are acids. 76.97.245.5 (talk) 22:26, 19 March 2009 (UTC)

I'm not familiar with the details about how they would react, but I would note that common writing ink until very recently was iron gall ink, made from iron compounds and tannin rich oak galls. -- 76.201.156.15 (talk) 03:32, 20 March 2009 (UTC)

Iron through wood accelerates the decomposition of the wood by feeding bacteria an essential element in short supply. Also you get the black staining due to the iron tannin compounds. Graeme Bartlett (talk) 05:22, 20 March 2009 (UTC)

So what could be used instead to have a similar appearance without any of these problems? And would steel have the same effect as iron? 148.197.114.165 (talk) 22:35, 22 March 2009 (UTC)

Synthesis of Vanillin from Benzene

I am currently studying organic chemistry, and I was curious how this particular synthesis could be accomplished. These are the steps I used, and I would like someone to tell me if they are correct. No, this isn't a homework problem, I was just curious how this could be accomplished. I know it's not the most economical way to synthesize it; I was just curious.

1)I used Friedel-Crafts alkylation (CH₃Cl & AlCl₃) to add a methyl group.
2)I added a diazonium group to the para position using NaNO₂ and HCl.
3)I added PCC to oxidize the methyl group to an aldehyde. I'm not sure if I used the right oxidizing agent here.
4)I brominated the compound with Br₂ and FeBr₃.
5)I replaced the bromine with a methoxide group by adding sodium methoxide.
6)Finally, I converted the diazonium group to a hydroxyl group by adding an aqueous acid (H₃O⁺).
CalamusFortis 21:59, 19 March 2009 (UTC)

PCC may not work. PCC generally is specific for taking alcohols to carbonyls. I don't think it is strong enough to take a simply alkyl group all the way to the carbonyl. The other steps look OK, so long as the methoxide will not also substitute the diazonium. You may also want to protect your aldehyde once it is made; else you may end up with unwanted side reactions like the Aldol condensation. See Protecting group for more info on this. --Jayron32.talk.contribs 23:47, 19 March 2009 (UTC)

I see a few problems here, especially if this needs to be any sort of practical (vs "looks possible on paper") approach:

1 Getting a methyl electrophile is probably pretty hard (think about stability of carbocations). Might work, but would be easier to put on...well anything else. Given that you're going to oxidize it, could even be an ethyl or isopropyl, since those additional carbons can be cleaved in step 3.

2 To get diazonium (Ar-N₂⁺), you use those reagents starting from Ar-NH₂. For a simple aromatic, those give you the nitroso (Ar-NO). Which could be reduced to the amine.

3 Jayron is right...PCC only oxidizes alcohols well. Need something stronger and mechanistically different for benzylic position (I think KMnO₄ is standard).

4 Your ring is *very* electron-deficient at this point (diazonium and aldehyde are electron-withdrawing) so doing another electrophilic aromatic substitution is probably too slow to be practically useful. And I don't think you would get good positional control. Diazonium is probably a strong meta-director and you want to Br go ortho to it.

5 Given how electron-poor the ring is (now with 3 inductively withdrawing groups!) an addition/elimination mechanism for this substution might work, but it's clearly *not* an S_N2-type displacement and you have the risk of forming benzyne and then getting the nucleophile adding at a different position. Heck, you've got the diazonium too, which is a much better leaving group. Although it might be unlikely for it to have stayed attached this long.

Overall, might be better to activate the ring first as aniline, then put the para and then ortho substituents on (the NH₂ would make the electrophilic reactions go faster whereas diazo and carbonyl each make it go slower), and last diazotize and convert to the hydroxyl. DMacks (talk) 00:04, 20 March 2009 (UTC)

It should also be noted that synthesizing ANYTHING from benzene is pretty much a pointless exercise; benzene is fairly chemically inert, and substituted aromatic compounds are readily availible. It's about as useful as synthesizing anything with only methane as a starting material. It is theoretically possible, but practically pointless. Our article on Vanilin gives numerous other synthetic pathways to make it, and none are as convoluted as taking it from unsubstituted benzene. If this is a homework problem, I sympathize with you, and say that you should have enough between your initial ideas and those of myself and Dmacks excellent additions to put together a workable synthesis; just know that this is a purely academic exercise; no real chemist would do it this way... like, ever... --Jayron32.talk.contribs 02:54, 20 March 2009 (UTC)

Free will

Everything is life is subject to the laws of physics, and therefore act accordingly. If you drop a rock it will fall down, if you flip a coin it will fall with some outcome. My question is, isn't everything predetermined? Because everything I do, every action every human being and object does in the world is because of the laws of physics. Am I right in saying that if you flip a coin, flicking it with your thumb with a specific amount of force in a specific environment (something like wind, no wind, rain) everything happens because of physical interactions (e.g. a drop of rain falling on the coin) and could only happen in one way. What I wanted to know, is this true? Is there anything in nature that's random? Is there anything that, given the same environment, given the same forces and objects at the same time- would result in something... else? Can two occurrences that are completely the same in every possible metaphysical (I don't know what that word means, it just sounds smart) manner end up.. not being the same?

I hope I've gotten my point across, what I basically mean to ask "is there anything in life that is really random". I don't have much knowledge of quantum mechanics but I've heard that on a quantum level random things do occur, but my question is whether they are really random? To someone like me who doesn't know much about quantum mechanics, it seems impossible that two coin flips that are the same and are affected by the all the same forces and hit the exact same table on the same place should produce different results. If so, how can there be free will if every action we take is because of some chemical or physical reaction in our environment or bodies? --BiT (talk) 22:31, 19 March 2009 (UTC)

You might find the articles about chaos theory and the butterfly effect interesting. They show that even in a truely deterministic world there is still room for unpredictability. With respect to your question about quantum mechanics: Yes, in the standard interpretation of quantum mechanics there is true randomness in many situations, radioactive decay for instance. Dauto (talk) 22:56, 19 March 2009 (UTC)

I would like to add that despite the fact that your line of thought is quite common, I find it very puzzling. I see free will as a sentient being's ability to make good choices given the circunstances. Good choices are more often based on logic than on randomness. Dauto (talk) 23:15, 19 March 2009 (UTC)

No - there are at least two or three reasons why things aren't predetermined...firstly there is quantum randomness - secondly there are chaotic systems. Both of these things guarantee that at least in some situations you can't predict the outcome of some future event with perfect certainty. At least once during the infinite life of an infinite universe, all of the molecules in your rock will spontaneously leap 6" to the right and not fall as you expected. Well, OK - that's pretty rare - but there are certainly 'macro-scale' things that you can't predict. There IS perfect randomness.

However, I don't think you can parley "randomness" into "free will". I don't think we have free will...quantum randomness and chaos theory notwithstanding.

SteveBaker (talk) 23:20, 19 March 2009 (UTC)

SteveBaker, I agree with you that quantum randomness is a red hearing in discussions about free will. What I don't understand is why so many people equate determinism with lack of free will. As I see it, exactly the opposite is true. Total randomness destroys free will and determinism preserves it. Dauto (talk) 05:50, 20 March 2009 (UTC)

I find it rather difficult to define "free will". It requires a concept of conciousness that is somehow outside of science in order to make any sense. --Tango (talk) 23:37, 19 March 2009 (UTC)

It's a common misconception that true randomness can be found in chaos theory. In fact it cannot. A quick read of our own article will show that these systems "appear to be random" and "this happens even though the system is deterministic". Chaos theory is about systems where the tiniest deviation in the starting condition can produce huge changes in the end condition, which makes them practically impossible to predict, but they are in principle predictable. DJ Clayworth (talk) 23:38, 19 March 2009 (UTC)

I strongly disagree. Chaotic systems might be predictable in principle - but only if you have literally infinite precision in the measurement of initial conditions....but you don't...you CAN'T - you don't have enough paper to write down all of the digits of data to put into the calculations - and there isn't enough energy in the visible universe to crunch the numbers. Even without resorting to "oh no - you can't measure things that accurately because that nice Mr Heisenberg said 'No'."...a completely classical system can be literally impossible to predict. SteveBaker (talk) 03:32, 20 March 2009 (UTC)

When we're talking about a philosophical subject like Free Will, the question is "is the future determined" not "can we predict the future". Chaotic systems are determined, whether or not we can predict them. I would submit that to deny that the future is determined we have to invoke Heisenberg and quantum; chaos theory won't do it. DJ Clayworth (talk) 14:13, 20 March 2009 (UTC)

Well - I suppose at that extreme (both of logical position and linguistic interpretation!) - you are right for truly 'classical' systems when you are only talking about predetermination and not prediction. But - of course - there are quantum effects that are truly random (in the not-predetermined sense). What chaos theory does in the real world is to magnify the true uncertainty of the quantum world into macro-scale uncertainty. In a system such as when the ultimate position of a metal-tipped pendulum swinging over two strong magnets is determined by it's starting position in a 'fractal' manner, and for some regions, the initial position of the pendulum has to be known to literally infinite precision - but for quantum/heisenberg reasons, we know that's impossible. Hence the final position of the pendulum is indeed both entirely unpredictable (even in principle) and not predetermined (in the sense that quantum effects are not predetermined). The chaotic nature of that system magnifies quantum uncertainty to macro scales. So even something as 'classical' as a pendulum over two magnets is affected by quantum randomness - and that's enough to bust open predestination. However (as I said before) I don't think that opens things up to "free will" since we cannot influence either the macro-scale chaotic system that is our brain or the quantum randomness that drives that unpredictability. I suppose if you want to equate free will with some quantum-scale randomness, then you have your "get out clause" - but it's not very convincing. SteveBaker (talk) 14:45, 20 March 2009 (UTC)

Thanks. I completely agree with you. I guess we can summarise as "quantum effects generate true randomness at the microscopic level, and chaos theory says that those microscopic causes can have macroscopic effects". DJ Clayworth (talk) 15:18, 20 March 2009 (UTC)

i think that evry thing run with aperfect order ... random theories is a sily way to avoid looking for answers , evry action on this universe will affect the whole universe by the way under the same conditions.

the problem that we are trying to explain the whole universe while we're still ignorant about alot of the world basics,even in the most trustable theories in science we have to assume that the light travel with qunstant velocity , while its not, but this assumption could twist the theory so much in ahigher level , and thats why as the science keep going we try to come up with a more accurate theories .

when you try to build lets say a 1000 mile\ hour car you will need more accurate calculations than the ones you will use to build a 150 mile\hour car .

we always try to simplefy evry thing so we can predict it , and there were evry thing goes wrong . and when evry thing go very very complex for our minds we start to use this randomness theories . —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 02:01, 20 March 2009 (UTC)

Well - you're in good company. Albert Einstein refused to believe it too - but sadly, the fundamental randomness of the subatomic world is all too real. If your computer has flash-memory in it - then it only works because of quantum randomness. This is more than just some maybe-true theory - we can do real engineering using it and produce real products that depend on it. SteveBaker (talk) 03:35, 20 March 2009 (UTC)

I apolgose for sounding arrogant, but most people here (except Tango) are missing a very important point because they are so used to the determinism of physics being the unviolable constant in natural science. Let's start at the beginning... the determinism of physics was discovered through the efforts of various scientists like Galileo and Newton who deciphered various physical laws that governed the behaviour of physical bodies. Determinism wasn't always the accepted (or intuitively correct) principle. The discovery of physical laws went up to make up the edifice of physics which was governed by fixed laws. These laws, until the discovery of quantum processses, meant that you could predict the behavious of any physical system accurately as long as you know the state of the system (position and velocity of particles) at a given point. Now here comes the important part... at some point people (like our OP) make the mistake of extend the determinism of PHYSICS to humans as if humans were nothing more than physical systems. The difference is that there is an entity called the will, which comes into the picture to decide how we will behave. This entity of the will lies outside the purview of Physics. I am not talking matphysical mumbo jumbo here. It is an important question in the study of the philosophy of mind - extending to the concepts of materialism/dualism/idealism. In short, the determinism of the physical world does absolutely nothing to undermine the existence of free will - and you don't need quantum indeterminism or chaos theory to account for that. The question of free will is fundamentally a philosophical one, not physical. --ReluctantPhilosopher (talk) 07:28, 20 March 2009 (UTC)

What was the arrogant part - that you claim humans are more than just "physical systems" with no evidence to back it up? To me all the evidence points to humans being organisms, with which our "will" helps us maintain homeostasis and ultimately reproduce. Although the physical system can act differently, i.e. in suicide. Depression is still a very complex disorder which isn't well understood and many brain regions are involved, so I can't say specifically what is wrong which would lead to a human to kill itself. --82.21.28.65 (talk) 11:11, 20 March 2009 (UTC)

"you claim humans are more than just 'physical systems' with no evidence to back it up" - well there is no evidence to the contrary either. You are basically arguing the case for materialism. Materialism states that everything is fundamentally physical, with "will", "conciousness" etc. just being words we throw about to account for our experiences. Well it's not a settled question - and the debate is very much alive on it. Dualism and Idealism are other alternatives. I personally believe in a sort of dual aspect theory --ReluctantPhilosopher (talk) 11:55, 20 March 2009 (UTC)

Well, you're the one positing an extra-physical "will", so you're the one obliged to do better than saying "there's no evidence to the contrary". --Sean 14:11, 20 March 2009 (UTC)

Well I am not the only one positing an extra-physical will - as I said it's a subject of philosophical discussion. Will, consciousness, mind - do they exist independent of the physical - it is the subject of philosophy of mind. --ReluctantPhilosopher (talk) 14:38, 20 March 2009 (UTC)

Btw, I would perform the gargantuan feat of solving the mind body problem if I could "do better than" just stating what the different viewpoints are :D --ReluctantPhilosopher (talk) 14:51, 20 March 2009 (UTC)

Einstein only refused to believe in it until there was an overwhelming amount of evidence for it. Once that evidence was provided he accepted it, as any good scientist would. --Tango (talk) 12:39, 20 March 2009 (UTC)

I'm not sure that that is correct. My understanding is that Einstein never accepted quantum mechanic's indeterminism and tried until his death to find a deterministic model. A Quest For Knowledge (talk) 13:09, 20 March 2009 (UTC)

Well, yes, I guess you are right - he accepted most of QM, but not the Copenhagen interpretation of it. As I understand it, it was about 17 years after his death that experiments were performed that conclusively showed things like the EPR paradox should be resolved in favour of QM. I don't think he disagreed with anything that was firmly supported by experimental evidence that was available to him (although I could be wrong - I haven't studied the matter in any depth). The point I was trying to make (rather unsuccessfully, perhaps) was that arguments to authority along the lines of "Einstein didn't believe in QM, so neither do I" are seriously flawed since we have access to more experimental data now than Einstein did when he made those statements. --Tango (talk) 14:42, 20 March 2009 (UTC)

Unfortunately, my knowledge of physics only extends to one college physics class and whatever's on the Discovery and Science Channels, but apparently some people are still trying to come up with a deterministic model. [11] A Quest For Knowledge (talk) 15:18, 20 March 2009 (UTC)

There are always a few people on the fringes that disagree with everyone else. Without them we wouldn't have paradigm shifts, so they have an important role in the scientific community, but until other scientists start agreeing with them it's best for us non-scientists that don't understand the subject well enough to pass judgement on their theories to just assume the majority are right. --Tango (talk) 17:20, 20 March 2009 (UTC)

Carbon Fiber

What exactly is the tensile strength for carbon fiber? And how much does it cost? I can't find the information anywhere. I thought this might be a good place to ask. <(^_^)> Pokegeek42 (talk) 22:42, 19 March 2009 (UTC)

Our article gives a value of 5650MPa or 820,000 psi for the tensile strength, but note from this source "Overall, the strength of a carbon fiber depends on the type of precursor, the processing conditions, heat treatment temperature and the presence of flaws and defects"[12]. Mikenorton (talk) 23:01, 19 March 2009 (UTC)

Also, the tensile strength for carbon fiber will depend on the orientation of the fibers, as well as the matrix you use to bond the fibers. It is entirely possible for the tensile strength for a force in one direction to be 2x that in another direction. Also, the manufacturing process will introduce errors that can weaken the carbon fiber, so there is not really a simple answer to this question. As far as cost goes, I am not sure, but I believe a lot of the high costs associated with carbon fiber is not so much the cost of materials, but the cost of labor. It is time consuming to manufacture if you want quality stuff.65.167.146.130 (talk) 13:30, 20 March 2009 (UTC)

hair drug tests

would washing your hair with aloe vera,chlorine,bleach and other cleaning chemicals gaurenty passing a hair drug test?? —Preceding unsigned comment added by 76.14.124.175 (talk) 23:08, 19 March 2009 (UTC)

Probabily not. It might make it obvious that you tryed to hide your past drug use though. Dauto (talk) 23:18, 19 March 2009 (UTC)

No - the drug residues are inside the hair - not on the outside where it could be washed off. I guess you could shave it all off...that would make it kinda difficult to test! But don't forget it would have to be ALL of the hair on your body....hmmm - I guess that also might make it obvious that you tried to hide your past drug use. SteveBaker (talk) 23:27, 19 March 2009 (UTC)

(EC with SteveBaker) Hey... My wife did her master's thesis research on drug testing in hair, so she is uniquely qualified to answer this. According to her, the drugs are bound in the structure of the hair itself, and any topical washing is going to have no effect on this. Even treatments like bleaching and the like will not remove it; it may reduce the concentration slightly, but there is no way to remove all traces of the drugs from your hair. According to her (who spent two years studying this exact thing, mind you) the only way to get rid of the drugs is to get rid of the hair. Good luck with that! --Jayron32.talk.contribs 23:29, 19 March 2009 (UTC)

Our article on drug testing notes that hair testing can be done on just the follicle, so shaving won't, er, cut it either. Better hope for a case of this instead. - Eron^Talk 23:31, 19 March 2009 (UTC)

Wouldn't that only detect very recent drug use, though? The idea of testing hair is that it can detect drugs that were in the system when that hair was grown, which could have been some time ago. I think shaving your head would work as long as you haven't used drugs in a long enough time that the hair anywhere else on your body isn't long enough (and therefore old enough) to contain traces of them. --Tango (talk) 23:35, 19 March 2009 (UTC)

Indeed, detectable compounds only remain in the folicle for a short while. Folicle testing could, in theory, tell if you recently smoked a j... But hair testing can show that you smoked one last year... Or last month, or smoked most of last year and stopped six months ago. Its pretty neat stuff... --Jayron32.talk.contribs 02:48, 20 March 2009 (UTC)