Wikipedia:Reference desk/Archives/Science/2009 March 20

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March 20

Supernova confusion, and the fate of nearby/bright stars

Hi. The article on Supernovae states that type Ia supernovae are the result of star-dwarf interactions, type Ib and Ic are the result of truly massive stars, possibly Wolf-Rayets, and that type II supernovae have a mass of at least 9 solar masses. However, this causes a contradiction. The article on the Chandrasekhar limit states that stars with masses greater than 1.4 solar masses will collapse into a neutron star rather than a white dwarf, therefore initiating a supernova. Or, is this defined by the mass of the star in the late phase of its life, when it has burned the hydrogen and helium and begins to swell, thereby losing some of its mass? I see that most stars visible in the night sky do have masses greater than 1.4 Sol. Why are there not more supernova explosions in our own galaxy, then? Is it possible for stars to gain significant mass during their lifetime, other than by ingesting material from a companion? The article on black holes does not mention this, but I read somewhere that a star having a mass over 6 Sol is a good indication it may collapse into a black hole (assuming that any core remnant is not destroyed). Also, when two medium-mass stars with similar masses in a very close binary system collide (due to gravity in the system shrinking their orbits, not a by-chance collision), is the result a supernova or a hypernova? The article on supernovae does not mention this category, and apparently hypernovae refer only to hypergiants collapsing.

If the limit for a star to end as a supernova is indeed 1.4 Sol, then looking at the top ten brightest stars in the sky, it looks like that Arcturus and Vega will explode as supernovae; Sirius and Procyon will also explode as supernovae, but interactions with their companion dwarf star could initiate a type Ia instead; Canopus and Achenar will explode as supernovae, and are just massive enough to perhaps end as black holes, Rigel and Betelguese will be especially energetic supernovae resulting in black holes; Rigil Kentarus will have one star swell to red giant first, probably star A, then shed its outer layers, and if the explosion doesn't significantly disrupt the second star, then possibly its remaining material will migrate towards the remnant of star A; Capella appears to be a binary system of two stars massive enough to generate supernovae, perhaps the explosion of one will disrupt the other, or else we could have stellar matter being drawn towards a neutron star. Most of these stars will probably be well away from Earth, though, by the time the explosion occurs, because a positive radial velocity would cause the star to be farther away, and a negative one probably means the star will have long receded by the time the explosion occurs. Or, is there something I'm missing here? Would this mean that supernova explosions are likely to be common near Earth, and would they significantly affect our atmosphere?

Also, what exactly are the evolutionary phases of higher-mass stars (those heavier than 1.4 Sol, specificly)? Does a blue giant evolve to a red supergiant, does a blue supergiant evolve any farther before exploding, what about white and yellowish-white stars in this category, are they still the young versions of red giants or red supergiants? Also, in the case of supergiant-black hole interactions, such as with Cygnus X1, what is expected to occur when the supergiant itself goes through the end of its life cycle? Thanks. ~AH1^(TCU) 01:29, 20 March 2009 (UTC)

Wow, so many questions... I won't tackle all of them. The gist of most of what you are asking seem to boil down to "what happens to stars that are heavier than chadrasekar's limit but are lighter than 9 solar masses? Some of them will end their lifes as Planetary nebula. This page has a nice explanation. Dauto (talk) 03:18, 20 March 2009 (UTC)

Nothing ends up as a planetary nebula - as that article says, it's a short-lived phenomenon. --Tango (talk) 12:35, 20 March 2009 (UTC)

My point was that after shedding the outer layers on a planetary nebula the 5 sol star isn't a 5 sol star no more. So that's the end of the 5 sol star. Dauto (talk) 13:38, 20 March 2009 (UTC)

Hi. OK, so it appears middle-weight stars usually end up with a much lower mass. What happens, however, with binary systems like Sirius and Procyon, does the white dwarf absorb the extra material and end up as a type Ia supernova? Also, is it possible to predict whether a star such as this will lose most of its mass or not? Thanks. ~AH1^(TCU) 17:14, 20 March 2009 (UTC)

hair tests again

thanks for the aswers. but i'm confused...if ur hair takes in drugs....does that mean almost any chemical put in our bodys go in the hair? or is God just getting back at stoners? —Preceding unsigned comment added by 76.14.124.175 (talk) 02:03, 20 March 2009 (UTC)

ps. doea ethnicity affect hair tests? —Preceding unsigned comment added by 76.14.124.175 (talk) 02:19, 20 March 2009 (UTC)

Asking my wife again. It's not that everything you take in ends up in your hair, but most drugs have chemically very similar chemical compositions, and those compounds do tend to accumulate in the hair. After all, the basic idea of drugs is that they mimic chemicals in your brain, and those chemicals also tend to accumulate in certain places like hair and fingernails. It isn't that ONLY drugs do, its that drugs are one of the things that do accumulate there. There are many other things that do, like heavy metals and arsenic, and hair tests can be used to show that a person has been poisoned over a period of time. The deal with hair is not that it magically absorbs drugs; its that it lasts a LONG time, so it carries a record of things you have taken in over a long time. And, ethnicity does effect hair type; your ethnicity can be positively identified by microscopic analysis of your hair... however no person or ethnicity is immune from these hair tests. Again, your only option is to shave your head; however if you shave it after being told that you need to give a hair sample for a drug test, then they will likely know exactly why you did so. Your options are a) don't do drugs or b) don't apply for jobs where it matters... --Jayron32.talk.contribs 02:46, 20 March 2009 (UTC)

I don't believe shaving your head will do the trick. We don't have hair only in our head. There are also other ways of testing for drugs - read drug test for more, but they don't have a long detection period like hair test.--80.58.205.37 (talk) 12:54, 20 March 2009 (UTC)

Are humans the fastest long distance runners?

When it comes to the fastest on land, everyone bows down to the sprint of the cheetah. But beyond the sprint, what is the fastest land animal over a substantial distance, let's say 50 miles or so? I've recently heard an assertion that we, as a species, were very successful in our infancy because we evolved to be the best at tracking herds over very long distances. Sappysap (talk) 02:37, 20 March 2009 (UTC)

I've heard that said, many times. It may be true...but I don't think so. Marathon runners can do 26 miles without a break. However, in the Man versus Horse Marathon - the race was won by horses in the first seven years although a human did win on the eighth event - but on a bicycle (which, IMHO, is cheating). The race was run for 25 years before the first human won on foot. In 28 years of running the event, only two humans have ever won on foot. For some reason that's only a 22 mile race, but it's cross-country - which may give the horse an unfair advantage. But then consider that they horses are HEAVILY handicapped by having to run with a human rider on their backs! If the runners had to carry a 40lb backpack - I think it would slow them down too!

So it's abundantly clear that 22 miles isn't enough to give the human a winning advantage. I had a neighbour in England who was a big time long-distance runner. He did the London-to-Brighton foot race (which I think is 50 miles or so) - also several double-marathons (52 miles) and the South-Downs-Way run (I believe 70 miles) and the Isle-of-Wight race which is also some crazy long distance. But I don't think an average human can do that - even with training.

I dunno - I think it's a tough sell. SteveBaker (talk) 03:04, 20 March 2009 (UTC)

Yes, true. But may be the 'Man versus Horse Marathon' isn't the best way to test the hypothesis. Horses, after all, are pretty good long distance runners themselves. May be we would do better against animals more adept of short bursts of very fast sprints like impalas? Dauto (talk) 03:54, 20 March 2009 (UTC)

Harvard anthropology professor Daniel Lieberman claims we are "the animal world’s best distance runners."[1] Clarityfiend (talk) 04:20, 20 March 2009 (UTC)

26 miles is a single marathon. Many people can do it - probably most healthy adults after a year or three of training. See Ultramarathon for really dedicated runners. --Stephan Schulz (talk) 09:12, 20 March 2009 (UTC)

But to find out if we're the best we need to compare ourselves to others that are very good. --Tango (talk) 12:26, 20 March 2009 (UTC)

Humans can run 3,100 miles over the course of 41 days. Does anyone know if a trained horse could do the same? --Sean 14:16, 20 March 2009 (UTC)

But here is my hypothesis in a nutshell: We know that most people (my wife, for example) can more or less run 26 miles - with a bit of training (she's never run a race over any distance in her entire life - she trained over two months - and finished the London Marathon in a hair over 5 hours - although she did walk some of the way). It's not unreasonable to suppose that pre-soft-living-modern-civilisation-humans could all run at least 26 miles if they had to. But we also know from the Man-vs-Horse thing that AT LEAST the one species we've seriously tried this against can beat us easily over 22 miles WITH A HUGE LOAD ON THEIR BACKS. So I'm betting that horses without riders would have no problem whatever in whipping our asses out to at least a few miles beyond the regular marathon distance. However, we have these ultramarathon loonies who run 50 mile races. It's perfectly possible that the horse gives up at about 30 miles...and that SOME humans can make it out to 50 miles. But if we're taking about maybe 1000 people in the world who run ultramarathons - that's the top 0.00001% of humans. I'm pretty sure we couldn't all do that - even with training. And what if we picked the very best long-distance horse out of all the horses in the world - and trained the heck out of it. Gave it really nice Nike running horseshoes and a digital heart-rate monitor with integrated pace timer - no rider, no saddle - and made sure it had specially formulated 'rehydration' stations every few miles...wouldn't the best horse manage equal amounts of improvement over the general population of horses? I don't think there is any evidence whatever that a 'typical' human could out-run a 'typical' horse over any significant distance...and I don't believe that the top 0.0001% of humans with the best training and support facilities could beat the top 0.0001% of horses if they were given fair training and support (and no riders!). And that's just horses. What about all of the other long-legged runners of the world? I think this one is busted...unless there is some solid evidence to the contrary. SteveBaker (talk) 14:22, 20 March 2009 (UTC)

Wait, that's not a fair comparison at all! Horses have been bred for centuries for speed, endurance, carrying capacity, etc. How would a horse's pre-domestication ancestors fair in a human-vs-Equus ferus marathon? APL (talk) 01:09, 21 March 2009 (UTC)

How is that fair either thought? Prehistoric humans were probably quite fit but I doubt they compared to modern professional marathon runners at running such long distances. Nil Einne (talk) 14:05, 22 March 2009 (UTC)

There are other animals besides horses to consider as well. What about wolves? 65.167.146.130 (talk) 14:57, 20 March 2009 (UTC)

Let's play devil's advocate for a bit... Okay, so an average horse could beat an average human in a single race of 50 miles. How soon until it can go another 50? I imagine it would take a lot longer to refuel a horse than a human; in fact, if the human slowed to a walk here and there, it could refuel on the run to some degree, or at least take in some water. Quadrupeds can't do that. The horse is going to need enough energy to haul its 1,000 lb carcass across the plain, while the human only needs to haul its ~150 lb carcass, and gets to take in higher calorie foods to boot (including, er, horse, but that's a bit rude to your opponent...). Sooner or later the issue of fuel quality and fuel consumption are going to overwhelm any short-term equine superiority. Maybe. Matt Deres (talk) 20:14, 20 March 2009 (UTC)

Interesting point - I hadn't thought about it that way. However, horses are capable of eating grass, which is generally more readily available in large quantities than food suitable for humans. --Tango (talk) 20:34, 20 March 2009 (UTC)

See Persistence hunting. Wolves quite probably could beat humans as they also do something similar, I don't know. It would only need a good fit person to run down a horse without a rider though, they wouldn't need to be Olympic standard or anything like that. And by the way I've run longer than that 50 miles of those 'ultramarathon loonies' ;-) Dmcq (talk) 22:40, 20 March 2009 (UTC)

Why do you say that? As SB has mentioned given the conditions the horse with a rider is subject to, it seems resonable a horse without a rider would be capable of being faster. The question is would it ever actually run that fast if there isn't a rider edging it on? Well it's difficult to say IMHO. As I've mentioned below, in general we can expect most animals wouldn't. But if you are chasing a horse as a prey and the horse realises you are a predator it seems to me easily possible the horse will actually run that fast Nil Einne (talk) 14:33, 22 March 2009 (UTC)

I just had a good read of the Nature article referenced at the end of the wiki article on the evolution of endurance running in humans and it says some dogs and horses that have been bred for endurance would probably beat humans. The wolves article says they normally give up chasing after a fairly short distance but one was observed hunting a moose for 35km. Another animal that possibly would beat humans is the kangaroo. Dmcq (talk) 17:46, 21 March 2009 (UTC)

The refueling thing is an interesting point. It's worth remembering many (not all obviously) marathons don't involved the runners bringing their own water. Nil Einne (talk) 14:07, 22 March 2009 (UTC)

IMHO one issue we're not addressing is the difference between what can be done, and what is done. Personally, it wouldn't surprise me if a number of animals can beat humans in general. However many of them are never going to do it in practice. Similarly while humans may have evolved endurance for long hunts, what sort of distance are we talking about here? Did humans really chase animals by running after them non stop for 50 miles? Nil Einne (talk) 14:11, 22 March 2009 (UTC)

Without having read the article that Sappysap is referring to, I wonder if it's solely referring to our endurance or it may also refer to our intelligence etc. I presume one advantage humans have is that they have endurance and also intelligence. Let's say you are chasing something. Perhaps it's about the same speed as you so you don't really catch up to it and it doesn't escape. Eventually you tire and slow down (or perhaps you could go on but decide the current run is pointless). It 'escapes' and then slows down itself. Trouble for it is you may rest and 'refuel' and then go on. You can see it's tracks so you can easily still go after it. It doesn't know this so it's not necessarily running away from you any more. Eventually you may get close and it sees you and runs away again. Perhaps you repeat the same thing. It's easily possible you will ultimately win because you are chasing it in a direct line and wearing it down successful. It's not necessarily the case you have more endurance then it, you have good endurance sure but you are also smarter. Nil Einne (talk) 14:33, 22 March 2009 (UTC)

Plenty of animals are far better trackers than humans. Humans may have an advantage in a race to a pre-determined finish line because we can pace ourselves. I'm not sure any other animal would understand the concept of a long distance race well enough to do that. In a chase, though, pacing yourself doesn't really help unless you know how fast you and your opponent can run and for how long at various speeds and can work out a strategy to win, which would be rather difficult (an maybe impossible, depending on the respective abilities of the predator and prey). --Tango (talk) 14:40, 22 March 2009 (UTC)

You'd have to watch the episode in David Attenborough's series 'The Life of Mammals' where a Bushman runs a kudu to death to really appreciate what can be done. They typically have to run 25 or 35 kilometers which is nothing to a trained long distance runner. Dmcq (talk) 00:06, 23 March 2009 (UTC)

What is your point? So humans are better long distance runners than kudu, that doesn't answer the question. We knew humans weren't the worst, we're asking if they're the best. --Tango (talk) 00:12, 23 March 2009 (UTC)

You seemed to think it required special pacing. It doesn't. To win against other humans does. As to the best long distance runner I don't know but my best guess would be the kangaroo, I'd be surprised if humans actually are the best but they're very good rather than not the worst. I haven't a citation but I believe people in America in the past have run down wild horses rather than doing the sensible thing and creeping up and lassoing them. Dmcq (talk) 14:49, 23 March 2009 (UTC)

When the sun becomes a red giant...

About how long will it take for it to expand from its current size to red giant size (following the collapse of its core once the hydrogen there is used up)? 69.224.37.48 (talk) 03:09, 20 March 2009 (UTC)

See Stellar evolution which has words and pictures... --Jayron32.talk.contribs 04:31, 20 March 2009 (UTC)

Thanks! I should have thought to look there, as I looked at some related articles but couldn't find quite what I wanted. 69.224.37.48 (talk) 17:11, 21 March 2009 (UTC)

whats the origin of universe

its the biggest question ever ... what's the beginning , what's the source of evry thing .. if i said god is the source, atheistes will be angry.but if i said it's avery powerfull elian had created the earth ... i think they will buy that.

i just need to know whats wrong with god theory ... it might be right . but i think that humans dont like the idea of being a lower cretures ... we are so pride to be god slaves,we need so much to belive that there's no destiny ,so we can make our own.

human evolved from monky...monky evolved from (whay ever)...all the way to the creation of the universe ... from where did the universe came from ... from where that gas came from ... what is the first thing ... what is ground zero.

and if there is no god , and all this religion thing is just acrap,then i think the best thing that happened to the earth is hetler...we must let the smartest,the strongest , the healthiest ones to survive .who cares about moral standards ,we invinte these standards,and we can change them ,i think it's inmorale to leave the weak alife so they can multiply and reduce the chances of our survive,we should eliminate them.

and why do we evolve to have this huge power of thinking ... were we to needy to find answers for the question we had before we have the mind to ask.whats the need driven us to evolve to have this huge brain ... food ..???

will .. after all evry thing could be true , just leave the door open. —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 04:19, 20 March 2009 (UTC)

There are two (implied) questions you are asking, even if you don't realize it. They have different answers. Question 1 is "What is the process by which the universe was created" or "what went on when the universe came into being". Its a procedural question. The answer, as far as we can tell, is that some form of the Big Bang brought it about, somewhere in the neighborhood of 13-14 billion years ago. Now, while this satisfactorily answers your first implied question, it does not answer your second which is "What is the cause of the Universe coming into being" or "What is the purpose for which the universe was created". The answers to THOSE questions are ultimately unanswerable via direct observation or by inferences from those direct observation. Assigning meaning and purpose to creation isn't really the realm of observational study, so one must derive their own personal answer to the question. Did God make it so? Is it all random? Any answer you arrive at must be arrived at via faith, even if your answer is "The universe has no purpose at all". You may be interested in looking into the field of Cosmogony which discusses the philosophical (as opposed to the procedural) questions of the creation of the universe. --Jayron32.talk.contribs 04:28, 20 March 2009 (UTC)

Let me point out one thing you said that reveals you haven't thought about that long enough.

You said "i just need to know whats wrong with god theory ... it might be right . but i think that humans dont like the idea of being a lower cretures ..." If that was true, most people wouldn't believe in God. We know that that's not the case.

Now, if we skip all the senselessness about eliminating week people (not a very moral thing to say), we get to the only thing in your rant that actually sounds like a science question:

You asked "why do we evolve to have this huge power of thinking?"

To outwit one another in matters of love and war. Dauto (talk) 04:59, 20 March 2009 (UTC)

Oh, someone who concludes that if there is no God, Hitler is awesome because without God there's no morality! Why, sir, you have unintentionally created an argument for belief in God! What an amazing coincidence! -- Captain Disdain (talk) 10:53, 20 March 2009 (UTC)

As far as I understand it, evolution doesn't say that humans evolved from monkeys. Instead, it says that humans and monkeys evolved from a common ancestor. This common ancestor no longer exists (i.e. it is extinct). 12:59, 20 March 2009 (UTC) —Preceding unsigned comment added by A Quest For Knowledge (talk • contribs)

Well, yes, that's true. It's accurate to say we evolved from apes, but monkeys are a separate class of primate - it wouldn't be accurate to describe the most recent common ancestor of modern monkeys and humans as a monkey. (The most recent common ancestor of humans and non-human apes was an ape, though.) --Tango (talk) 13:12, 20 March 2009 (UTC)

Here we go again...

• its the biggest question ever - maybe - but I think I have bigger ones. Abiogenesis is one. Is there intelligent life throughout the universe is another. Are there parallel universes is a third. But this is right up there.
• ... what's the beginning , what's the source of evry thing - that's an easy one - the Big Bang. We're really very sure about that now. We know pretty much exactly what happened from about the first millisecond of existance. We still need to fill in some details about dark-matter and dark-energy - but we're definitely getting there.
• .. if i said god is the source, atheistes will be angry. - No, not angry. Saddened perhaps. Exhausted maybe.
• but if i said it's avery powerfull elian had created the earth ... i think they will buy that. - No, we wouldn't. That's really not what the science says and it wouldn't explain how the moon was formed from a collision between early earth and another Mars-sized planet. We don't need 'aliens with godlike powers' as a substitute for 'god' - we have strong evidence for a relatively mundane explanation that centers around stellar remnants, gravitation, that kind of thing.
• i just need to know whats wrong with god theory ... - it's "Unfalsifiable". That means that there is no conceivable experiment that could be done to either prove or disprove the theory. The "god theory" is (scientifically) no more and no less probable or provable or credible than that I made the earth and have been keeping quiet about it all these years. There are literally an infinite number of unprovable ("wild-assed") claims you could make - they all have equal status with the "god theory" - and we can't go around believing in an infinite number of random things. On the other hand - we have an exceedingly good 'conventional' theory that works perfectly well without hypothesising supernatural causes. God simply isn't necessary for our explanation of the universe. You might like to read about Occam's Razor.
• it might be right. - well, it might but so might be the theory that the Invisible Pink Unicorn (mhhbb) did it...or that roaming gangs of green furry fish did it. I can keep coming up with these stupid suggestions from now until doomesday - they are all just as valid as the "god theory" - there is the same amount of evidence that they are true (ie NONE) and just as easy to prove or disprove (ie IMPOSSIBLE). So why should we give the "god theory" a moment's more attention than the IPU (Invisible Pink Unicorn - mhhbb) theory - at least the incomprehensible but undeniable existence of pineapple and ham pizza provides at least a shade of evidence for the IPU? (I'm kidding - OK?)
• but i think that humans dont like the idea of being a lower cretures ... - that's true. When I was a kid - the text books said "Humans are superior to the animals because we have language and use tools." - but then we discovered that bees have a language (involving dancing and wiggling their butts) - and lots of animals use tools (watch a starling breaking open a snail shell by hitting it with a pebble). So the next generation of textbooks said "Humans are unique because we MAKE and use tools."...but then we found that chimpanzees strip the leaves off of thin branches to make tools for getting ants out of termite mounds...and there is a fish that cuts and shapes leaves to make a disguise that it holds over it's body so that birds can't see it swimming by. We are clearly at the 'top of the heap' - but reality keeps reminding us that we're really not that much more superior to the "lower" creatures.
• we are so pride to be god slaves,we need so much to belive that there's no destiny ,so we can make our own. - I certainly don't want to be a "god slave". I couldn't imagine what it would be like to believe in all that stuff. To have to continually bow down to an infinitely superior being? Urgh! We have not made up all this stuff we've found out about the universes. We've investigated what the universe has to tell us. We know the Big Bang is true because (in a sense) we sent up a spaceship to take a photo of it! The cosmic microwave background is the clearest proof that the Big Bang really happened. If you take the time to understand the science behind it - you'll be convinced too!
• human evolved from monky...monky evolved from (whay ever)...all the way to the creation of the universe ... from where did the universe came from ... from where that gas came from ... what is the first thing ... what is ground zero. - Ground Zero is the Big Bang. We're pretty solidly clear on everything that happened from then to now. What we don't know - and what (if you must) you could attribute to a "God" is what actually caused the Big Bang in the first picosecond of the life of the universe. I don't think we need a supernatural explanation for that - but if you must, you could imagine a god who decides to make the universe and after about a picosecond - steps back and lets it all roll out without touching anything after that. This makes a sort of sense I suppose. It's a "God of the gaps" argument. Wherever we don't yet have a scientific explanation - you can stick God in there. Sadly, those gaps are getting smaller every year. Science is making huge leaps in figuring this stuff out - and every time we plug a hole, there is less need for a god to make a workable explanation. Give it ten years and the role of god will have shrunk from a picosecond to an attosecond. But this raises a bigger question for me. You aren't prepared to accept that the "Big Bang" came from nowhere (despite good evidence pointing that way) - yet you are entirely happy to accept that God "just is" - nobody asks "what is the origin of god?"...but if we were (as scientists) to accept the god-theory, that would have to be the first and biggest new question. "Where did God come from?" When I ask that question, I get some vague hand-wavey thing about him always having been there - or "He's outside of time and space". But when I say that time actually started with the big bang - and that it's meaningless to ask what came "before" - you get all huffy about it and start demanding why I don't have an explanation. Your theory is certainly no better than mine - and Occam's razor says it's a lot worse because it involves a whole extra step that my explanation doesn't need.
• and if there is no god , and all this religion thing is just acrap,then i think the best thing that happened to the earth is hetler...we must let the smartest,the strongest , the healthiest ones to survive - but that's not true. Hitler's actions were not acceptable to the majority of humanity - or even to his own people when they finally realised what was happening. So Hitler was attacked from all sides - Europe, Russia, the US...and driven to extinction. He died because the majority of humans could not accept his behavior. That's because we've evolved a mental capacity to reflect the feelings of others - that capacity means that we can put ourselves into the positions of the poor people in those death camps - and we become outraged and belligerent - and we fix the problem. That's an evolutionary response to a failed genotype. Religion had very little to do with that. Plenty of atheists fought against Germany.
• who cares about moral standards ,we invinte these standards,and we can change them - some we can - others are so inbred into our genetics that we can't. You can't just decide to do something that's morally repugnant to you. I could no more kill my son than I could kill myself. That's not a matter of logic - it's a matter of what my brain chemistry has made me be. We are like we are because of the genetics of being a "pack animal".
• i think it's inmorale to leave the weak alife so they can multiply and reduce the chances of our survive,we should eliminate them. - you say that, but I doubt very much that you'd be able to carry it through. I have no god commanding me not to do that - and I certainly give money to help the needy - I volunteer to help out underprivilaged kids - I donate my time free to answer people's questions here on the Wikipedia reference desks. Without a god - your claim is that I should have no reason to do those things...yet I do! Gladly. For the betterment of mankind - for the survival of the species - for the survival of my genes into future generations. This is a moral standpoint for sure...but one that does not in any way rely on religion to prop it up. I actually agree with most of the more important of the Ten Commandments (although one or two of them are a tad nutty). "Thou shalt not kill" works very well for me! In fact, I'd prefer to avoid the weasel-words added to that that say "oh...unless it's a war or something...or maybe murderers could have the death penalty...and in Texas it's OK to shoot burgulars". No - for me, "Thou Shalt Not Kill" actually means what that bloody stupid book says it does. Not because there is some old white guy up in the clouds somewhere telling me to...it's because my brain tells me that killing (in general) is not a good thing. I have moral principles...pretty strong ones actually. They just don't derive from religion.
• and why do we evolve to have this huge power of thinking ... - it helped early humans to be smart. The smartest ones didn't get eaten by the sabre-toothed tigers - so they had more kids - who inherited their parent's smarts - and gradually, via the relentless force of evolution we evolved to what we are now. It's not in any way a mystery.
• were we to needy to find answers for the question we had before we have the mind to ask.whats the need driven us to evolve to have this huge brain ... food ..??? - Sex, actually. But food also.
• will .. after all evry thing could be true , just leave the door open. - No. It's ridiculous. I don't have the time to go around believing in green furry fish that MIGHT have created the universe - I don't have time to believe that there MIGHT be a teapot orbiting Mars right now. I don't have time for any of the hundred or so wildly different supernatural claims for a "god" or "gods" either. It's unnecessary and (frankly) ridiculous.

209.163.180.6 (talk) 14:01, 20 March 2009 (UTC)

Wow! What an inciteful reply! I think you should have used more CAPITAL LETTERS for EMPHASIS though. SteveBaker (talk) 14:04, 20 March 2009 (UTC)

OK - look I'm not playing sock-puppet-master here - I really didn't notice that my 30 day login period had expired on this PC.SteveBaker (talk) 14:04, 20 March 2009 (UTC)

We all knew it was you long before the signature line. Nimur (talk) 12:34, 24 March 2009 (UTC)

Green furry fish? What happened to the aardvarks (mtasnro)? Algebraist 14:26, 20 March 2009 (UTC)

In the Cyclic Model, the universe follows an infinite number of Big Bang / Big Crunch cycles, first cause isn't an issue because there is no beginning and no ending, just an infinite loop. "All this has happened before and will happen again." A Quest For Knowledge (talk) 14:03, 20 March 2009 (UTC)

I thought the whole universe was in a hot dense state and then nearly 14 billion years ago expansion started? Wait...have i been misinformed? 194.221.133.226 (talk) 16:14, 20 March 2009 (UTC)

Yes, that's right, although we have little or no idea what was going on just before that expansion started (or even immeadiately after it - there is a fraction of a second at the beginning during which our physics breaks down). --Tango (talk) 17:46, 20 March 2009 (UTC)

Is it too much of a sidetrack to ask what "mhhbb" and "mtasnro" stand for? Franamax (talk) 18:52, 20 March 2009 (UTC)

'mhhbb' stands, I believe, for 'may Her Hooves be blessed' and is a standard phrase when referring to Her. 'bbhhh' ('blessed be Her holy Hooves) and 'mhhnbs' ('may Her Hooves never be shod') are also in use. 'mtasnro' is a new coining standing for 'may Their ant supply never run out' and is a phrase used to propitiate the pink aardvarks who run the universe. Algebraist 19:02, 20 March 2009 (UTC)

In case mtasnro ever catches on, as of March 20, 2009, a Google search on the term returns exactly 2 hits neither of which are about the Pink Aardvark religion. A Quest For Knowledge (talk) 19:19, 20 March 2009 (UTC)

Thanks much for the info, faithfully recorded in my notebook! After Steve's analysis on the chances of being killed in a meteorite strike a while ago, I'm taking no chances on suddenly being called to the "undiscovr'd country from whose bourn no traveller returns". 'Scuse me now, I have to run out and find a goat, a virgin, a 100-foot tall flammable man-like structure and some chicken bones before nightfall. Oh yes, a box of ants too. :)

And to get even more sidetrack-ey, what's the name for when you find only one instance of a Google search term? Of course, when you report it, it then shows up twice. You were oh-so-close there! :) Franamax (talk) 22:43, 20 March 2009 (UTC)

Googlewhack, although it needs to be two dictionary words, random sequences of letters aren't allowed! --Tango (talk) 23:44, 20 March 2009 (UTC)

I get the feeling a lot more evolving of this power of thinking is needed. Or perhaps by then we'll all have evolved so the muslim faith or whatever is bred into our genes. Then nobody will have to ask - we'll all 'know' without any evidence just like the OP. Wouldn't that be a grand fate for our descendants. Dmcq (talk) 15:30, 23 March 2009 (UTC)

the iron content in steel wool lab queries

for an important lab we're doing titled "percentage of iron in steel wool", a sample of steel wool is placed in excess dilute sulfuric acid, and this supposedly converts the iron present in the steel wool into Fe2+ ions......then, the Fe2+ ions in the solution are titrated against a standard permanganate solution, and thus are further oxidised to Fe3+ ions, while the permanganate ions are reduced to Mn2+ ions..

do you have any idea of the kind of questions that are likely to be asked of me in this lab? also, i'm assuming my teacher will give a 'manufacturer's value of the % Fe'. do you know the equation to figure out the % difference between your value and the manufacturer's claim?

thanks heaps —Preceding unsigned comment added by Mtsa37 (talk • contribs) 04:45, 20 March 2009 (UTC)

Percent difference? That's a pretty technical article, but the essence is in the "Percent error" formula and the intro: it's a ratio of the difference between the values to the values themselves. You might take one value as "correct" and thus compare to it, or you might just take them both as "someone's data" and consider the average of them to be the value to compare. I would ask a student to write the net ionic equations for the redox reactions involved in this experiment. DMacks (talk) 04:56, 20 March 2009 (UTC)

You're likely to do stoichiometry calculations somewhere to figure out the mass of iron in your original sample. This can be done any number of ways, but since Fe3+ ions are colored, you could use a spectrophotometer, a series of standardized Fe+3 solutions, and Beer's law to calculate the concentration of Fe+3 ions in your unknown solution. Then, knowing that concentration and volume, you can find moles of Fe3+, which should ALL have come from the steel. You could also do the same via titration with a standardized KMnO4 solution; if you know the volume and concentration of the KMnO4, and have a balanced chemical reaction for the Fe+2/Fe+3//Mn+7/Mn+2 redox reaction, you can also quantitatively find the moles of iron in your unknown, and then its the same calculation as above. --Jayron32.talk.contribs 05:03, 20 March 2009 (UTC)

potential energy

I was watching TV where i saw a man working in a high way project , this man was trying to crack a big rock , he kept hitting the rock with a hummer until and suddenly it just split into half , i asked about it and get some opinions like a potential energy is being stored in the mass until its enough to crack the mass, but i think that the hummer is producing a hairy cracks at aspecified plan until its reach that critical edge where it to weak to resist that hit energy , so it jut crack down,what did you think....? —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 10:24, 20 March 2009 (UTC)

The rock is certainly not storing significant energy from the hammer blows. It's much more likely that each blow (or even only some of the blows) create and propagate cracks and fissures, gradually weakening the rock. At one point the rock is weak enough that the last blow splits it. --Stephan Schulz (talk)11:12, 20 March 2009 (UTC)

As a professional rock splitter, I concur with that. When trying to break up a rock down to a size that you can take back as a specimen you generally concentrate your hammering on any obvious existing weakness such as a crack or a weathered zone. Normally you can see, feel (from the change in the response of the hammer handle) or hear (a change in the sound of the blow) when you've started to propagate a crack just before it finally splits. Mikenorton (talk) 11:24, 20 March 2009 (UTC)

You could argue that a rock with cracks in it has higher energy that one that doesn't (in the same way that two separate atoms have higher energy than when they are bonded together), but there is no way easy way to get that energy back so I'm not sure I'd call it "potential energy". --Tango (talk) 12:17, 20 March 2009 (UTC)

When you're propagating a crack through a material, bond-splitting is what you're doing, so some of the input energy is converted to fracture surface energy. Mikenorton (talk) 12:27, 20 March 2009 (UTC)

I'd bet that you're actually releasing energy in the rock by breaking bonds - but the biggest part of what your hammer blows are doing ends up as heat or sound energy (which in turn is going to be heat energy pretty soon). When you hit the rock - you are causing it to vibrate or accelerate (briefly) - and that's getting turned into heat by friction. So to the extent that the rock gets a bit warmer (and most certainly the hammer does - you can feel it!) you are storing energy in the rock - but not usefully. SteveBaker (talk) 13:14, 20 March 2009 (UTC)

I'm sticking with using up energy to propagate a fracture, it's the basis of the Griffith approach to fracture mechanics. Mikenorton (talk) 14:06, 20 March 2009 (UTC)

Breaking bonds requires energy, it doesn't release it. That's the same for rock as for anything else. --Tango (talk) 17:11, 20 March 2009 (UTC)

During the recent gasoline price spikes, I imagine quite a few people "kept hitting a rock with their Hummer until suddenly it just split in half". I'm not sure if the junkyard would take half a Hummer, though. :-) StuRat (talk) 04:13, 22 March 2009 (UTC)

pls help...

what are the similarities and dissimilarities between prokarotic and eukaryotic replication,transcription and translation.59.92.238.182 (talk) 12:49, 20 March 2009 (UTC)

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:08, 20 March 2009 (UTC)

Also, use a descriptive title. --ReluctantPhilosopher (talk) 13:17, 20 March 2009 (UTC)

Do you mean prokaryotic and eukaryotic? DJ Clayworth (talk) 14:16, 20 March 2009 (UTC)

Transcription (genetics), Translation (genetics) look promising and weren't that hard to find. (Click on words in blue in a text on wikipedia and it will get you to the relevant page.) If the assigned textbook for your class doesn't give you good enough answers it might be useful to check if you have a well stocked library in the area. 76.97.245.5 (talk) 14:32, 20 March 2009 (UTC)

DNA replication and the sub-articles prokaryotic DNA replication and eukaryotic DNA replication would also be a good place to start. After digesting the information, if you still have specific questions, re-post them and I'm sure we'd all be happy to help. --- Medical geneticist (talk) 14:52, 20 March 2009 (UTC)

does anyone know??

what are the advanced drug delivery systems? 59.92.238.182 (talk) 12:50, 20 March 2009 (UTC)

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:08, 20 March 2009 (UTC)

Also, use a descriptive title. --ReluctantPhilosopher (talk) 13:18, 20 March 2009 (UTC)

Yes, wikipedia knows. Here's how you can find out what: copy your word into the white box underneath where it says "search" in the left hand sidebar near the top of this page. Then click on "search". If you can't find a relevant page or have trouble understanding some of the content, please feel free to come back with a specific question. 76.97.245.5 (talk) 14:23, 20 March 2009 (UTC)

can anyone help...

what is physiology pharmacokinetic model? 59.92.238.182 (talk) 12:52, 20 March 2009 (UTC)

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:09, 20 March 2009 (UTC)

Also, use a descriptive title. --ReluctantPhilosopher (talk) 13:19, 20 March 2009 (UTC)

Yes, wikipedia can help. Here's how: copy your word into the white box underneath where it says "search" in the left hand sidebar near the top of this page. Then click on "search". If you can't find a relevant page or have trouble understanding some of the content, please feel free to come back with a specific question. 76.97.245.5 (talk) 14:19, 20 March 2009 (UTC)

Start with the pharmacokinetics article. If that doesn't answer your question, re-post a more specific question and I'm sure we'd be happy to help. --- Medical geneticist (talk) 14:54, 20 March 2009 (UTC)

Solar Panels

If you put solar panels on windmills, could they help increase the energy given to the town or city or whatever the windmill's powering? What would you connect the solar panels to? <(^_^)> Pokegeek42 (talk) 17:38, 20 March 2009 (UTC)

I think putting the panels on the ground would be the best way to use the same space for solar and wind power. The alternative is putting them on top of the turbines (thus avoiding shadows being cast on them), but I suspect that would mess with the aerodynamics of the turbines and make them less efficient (whereas the shadows should be a mini\mal concern - turbines are pretty thin). --Tango (talk) 17:44, 20 March 2009 (UTC)

In terms of an individual windmill, its probably not all that efficient, but in terms of a national energy policy; diversifying one's energy sources is a sound idea. Generally, solar power is most productive at times and places quite different from the times and places where wind power is productive. Thus, they tend to complement each other as a source of power, but mostly so on a national rather than individual scale. In general, one windmill or a single solar panel running a single house, or even one of each, is a fantastically wasteful and inefficient way to do things. It would be far more efficient use of resources to provide power via Wind farms and Photovoltaic power stations. --Jayron32.talk.contribs 17:54, 20 March 2009 (UTC)

What an impressive generalisation, but it just squeaks through as accurate but very misleading. In general a small number of solar panels in a house is a pretty efficient way to provide thermal water heating as a top up to other energy sources. Solar for the summer and a wood chip boiler in winter is fine for all year domestic heating. Plenty of people use wind and wood for heating too (but not city ants). Local solar panels are also very efficient to provide local summer heating for things like domestic swimming pools. Only if you convert solar or wood to electricity (at massive inefficiency) does it look very uneconomic at home and equally it looks uneconomic for most climates as Photovoltaic power stations. The trade off between economic of scale and transport cost and loss depends on many things and is not obviously one way or another. --BozMo talk 18:37, 20 March 2009 (UTC)

When you consider transmission losses, local generation starts to look much better. But one windmill, even a utility scale one does not provide much area for the very inefficient photovoltaic power panels. You might get enough panel on the nacelle to get power one home. Rmhermen (talk) 19:25, 20 March 2009 (UTC)

However, covering the ground at a wind farm with solar panels might work quite well - wind farms are generally quite spread out and the area is often not used for anything else, as far as I know. --Tango (talk) 19:49, 20 March 2009 (UTC)

The windmill farms I've seen in the desert are not used for much, but the ones I've seen in the plains are used for cattle. Replacing their grazing land with solar panels will mean that the cattle need to graze elsewhere. Also, windmills require a lot of maintenance. It will be hard to work on one if you have to move a lot of solar panels out of the way first. -- kainaw™ 20:46, 20 March 2009 (UTC)

In Denmark, on-land wind turbines are quite commonly located on rural land and farming happens right up to the footprint of the turbine foundation itself which I believe is between 12 and 20 feet square. (And obviously the pathway needed to bring the maintenance equipment in counts as footprint too, but farmers need laneways for tractors anyway).

More desolate land, esp. deserts are good candidates for solar and mountains for wind - but yes, transmission losses, construction expense and bio-effects for the transmission lines come into play. There is a lot to be said for generation near to consumption, not least of which is grid stablization. If clouds pass over a remote solar plant or the wind calms at a wind-farm, everything in between supply and demand will see voltage effects, possibly quite severe. Franamax (talk) 22:54, 20 March 2009 (UTC)

The problem is that this idea is solving a non-problem. The problem with solar panels isn't in finding land to put them on. In all the places with the largest amount of sunshine, land is cheap. Deserts and prairie is easy to get for a couple of hundred bucks an acre. Compared to the cost of an acre of solar panels, the cost of the land is quite utterly negligable. So there is no need to make special considerations for putting them near windmills. To the contrary - you place windmills where the wind is good - you place solar panels where the sun is good - going out of your way to put one in the same place as the other is unlikely to be optimal. SteveBaker (talk) 23:35, 20 March 2009 (UTC)

The solar panels on windmills idea would be more of a benefit to home windmills, where space might be limited and trees and the house may cause shadows to fall on panels placed on the ground. If the windmill is on a tall mast, solar panels near the top would get more sunlight (the additional weight and wind-load might require a stronger mast, though). They could also be placed on the blades. In this case, the electricity could be transmitted from the moving blades to the rotating mast via brushes or some other method. StuRat (talk) 04:06, 22 March 2009 (UTC)

But that's a dumb idea...the windmill has to face into the wind - and the solar panels have to face towards the sun. Since there is little correlation between the two - you'd expect that either your windmill or your solar panels would be pointing the wrong way at least half of the time! Again, the limiting factor with solar panels isn't available area. Almost all houses have FAR more available roof area than the owner can afford to populate with panels. Going to all that grief to put a handful of solar cells onto the blades of the windmill (making them heavier - and therefore harder to get spinning in a light wind - requiring brushes to extract the power - which will inevitably add to the frictional forces - worse still - you are incurring all of those penalties during the night when the solar panels aren't paying for those additional costs!)...and all for what? About another three square feet of panels that's hardly ever pointing optimally? When did you last see a roof so packed with solar panels that another 3 square feet of them would be so urgently needed?! This is a STUPID idea....period. SteveBaker (talk) 19:39, 22 March 2009 (UTC)

Sure, there's a correlation. Just build your house somewhere where the prevailing winds are roughly southerly. (That doesn't affect your main point, of course.) --Tango (talk) 19:50, 22 March 2009 (UTC)

Then there's the problem that the house roof may be in shade in areas with tall trees (like my house), so not at all suitable for solar panels. Also, there may be a minimum amount of electricity required for a house, and any beyond that may be wasted (if there's no way to sell it back to the power companies in that location). In such a case, pointing the blades either at the wind or Sun may be enough. When there's no sunlight, point it into the wind. When there's no wind, point it into the sunlight. When there's neither, you're out of luck. StuRat (talk) 03:43, 23 March 2009 (UTC)

You've still greatly added to the complexity of a device that already is unlikely to pay for itself. If your solar panels need to be up on a pole, it'd probably be better to put them on their own pole.

You probably could think up some contrived hypothetical situation where a solar windmill would make sense, but you'd really just be searching for a problem to your solution. APL (talk) 12:52, 23 March 2009 (UTC)

Russell Watson Brian Tumor

Hi

Do you know the name of the surgeon who performed Russell Watson's brain tumor operation at the Alexadra Hospital in Cheadle (Greater Manchester) in 2007? Many thanksCarlchester (talk) 18:34, 20 March 2009 (UTC)

I couldn't find a specific answer to your question, but it will be one of the surgeons listed here. You might want to make further requests at the hospital itself. —Cyclonenim (talk · contribs · email) 19:13, 20 March 2009 (UTC)

Assuming of course that the surgeon has not moved on in the meantime and / or that the list is otherwise up to date - I note that a surgeon who operated on me is still listed on the hospital (I went to) pages, despite being suspended from the GMC :( 78.151.212.201 (talk) 21:59, 21 March 2009 (UTC)

Should I add this to an article? Electrolyzed water applications

This Reuters article caught my eye because I was just reading about other uses for Electrolyzed water. (Just ignore the snake-oil bits, I'm talking about mainstream uses like hospital disinfectants)

The Reuters article talks about using "electrolysis and ultra-low frequency waves" to raise sea water pH to 10 then spraying it in a scrubber stack to knock down soot, SoX, NoX and CO2 in ship exhaust. I wonder if it would also knock down heavy metal emissions, bunker oil being about the dirtiest thing in the world. The method described sounds very much like the process for producing electrolyzed water in commercial applications. (Again, I'm not talking about bottling it and scamming people into drinking it)

My request here is for some sage observers to look at the Reuters and wiki articles and tell me if it would be appropriate to add some verbiage and source to our wiki article to describe this use. And/or feel free to add it yourself!

And what the heck would ultra-low frequency waves have to do with this? Thanks! Franamax (talk) 21:48, 20 March 2009 (UTC)

I can't figure out the ultra low frequency wave bit. About the only thing I can think of is an ultrasonic cleaning effect, but the frequencies used for ultrasonic cleaners are far from "ultra low." (unless they're comparing sound frequency to light frequency but that doesn't make much sense). If the correspondent doesn't have a strong background in science (I have no clue about this guy), another possibility is that he could have messed up somewhere in the terms or facts so ultra low frequency waves refer to something else. Without putting too much thought into this, the alkaline electrolyzed sea water is basically a bleach solution. Perhaps the concept is to oxidize the NO₂, N₂O, and NO to NO₃^- and the SO₂ to SO₄^-2? The CO₂ I suppose would be removed when it dissolves in the alkaline water to form Na₂CO₃. I'm a little surprised because the calcium present in sea water would produce CaCO₃ which would build up as scale over time which wouldn't seem good for a ship. I am not sure about heavy metals. If they dissolved into the alkaline bleach water it would need to be treated to remove the metals before dumping it back into the ocean. Sifaka ^talk 23:15, 20 March 2009 (UTC)

There is some more verbiage on the website of Ecospec, the company that is marketing this thing. It sounds suspiciously like those gadgets that you attach to the fuel line in your car, that are claimed to improve your fuel efficiency, and has a familiar lack of any numbers or measurements. Caveat emptor. --Heron (talk) 12:30, 21 March 2009 (UTC)