Wikipedia:Reference desk/Archives/Science/2013 January 12

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January 12

Apophis 2029 and satellites

This talks about the 2029 Apophis close approach and it possibly hitting satellites. To me, that chance is so small that is is nothing to worry about. But is it massive enough to alter the orbits of (geosynchronous) satellites? Bubba73 ^{You talkin' to me?} 02:23, 12 January 2013 (UTC)

At 325 meters across, no. --Guy Macon (talk) 06:36, 12 January 2013 (UTC)

Satellites that must maintain an accurate station (this includes geosynchronous and GPS satellites) will have manoeuvring thrusters to adjust for any drift from the desired position. Far more substantial disturbances than a gravitational disturbance from a mass zipping rapidly past will be within the correction capacity of such thrusters. The question would more likely be a matter of whether the disturbance can be detected at all. — Quondum 11:08, 12 January 2013 (UTC)

Also note that the Earth would be deflected just like the satellite (although both by an amount too small to detect). The satellite would only be deflected slightly more since it is presumably closer. StuRat (talk) 01:07, 13 January 2013 (UTC)

Thank you

Resolved

Bubba73 ^{You talkin' to me?} 01:01, 13 January 2013 (UTC)

Mali

How come the french are fighting Islamists in Mali here http://www.bbc.co.uk/news/world-africa-20991719 but are not fighting them in Syria?--Jonharley667 (talk) 03:16, 12 January 2013 (UTC) ^{This account is a sock puppet of Wrk678 and has been blocked indefinitely}

Lots of reasons. They're 100% Islamist in Mali and in control of a large territory. In Syria, they're only one of a number of rebel factions. You can't even pinpoint where they are. Nor does France want to be seen supporting an evil dictator. Clarityfiend (talk) 03:57, 12 January 2013 (UTC)

One reason is that the Mali government has asked for aid in the conflict, whereas the Syrian government would likely be the opposing force were French forces to intervene. In this comparison it is easier to ally with an already formed government that has reasonably close ties to the people (Mali), than to attempt to side with very factional rebels against a more singular government (Syria). In addition, the scale of conflict is much different. The death toll and size of military forces in the Syrian conflict unquestionably dwarfs that of the conflict in Mali, if our entries on the subjects are correct. 2012-present Northern Mali Conflict, Syrian Civil War Lord Arador (talk) 03:59, 12 January 2013 (UTC)

Plus, as Clarityfiend has already noted, France is officially in opposition to the Syrian government(e.g. [1])), while in support of the Syrian Malian government. If France were to be on any side, militarily, in Syria it would be against the Assad government, not for it, and the Assads are definitely not Islamists. In Mali, they support the Government, so it's fairly easy to take a stand there with troops. --Jayron32 04:22, 12 January 2013 (UTC)

Did you mean to say the French both support and oppose the Syrian government ? StuRat (talk) 04:29, 12 January 2013 (UTC)

So corrected. Good catch. --Jayron32 05:08, 12 January 2013 (UTC)

My point was that the french (and others) are actively helping and arming Islamist rebels in Syria. --Jonharley667 (talk) 04:52, 12 January 2013 (UTC) ^{This account is a sock puppet of Wrk678 and has been blocked indefinitely}

Do you have any sources for that ? StuRat (talk) 04:57, 12 January 2013 (UTC)

Well, it's true: [2] But so what? Why should France (or any nation or person or anything else) be ruled by arbitrary and incidental similarities in their policies. The French support the anti-government forces in Syria (which contain some Islamist groups), while they support the Mali government (which is fighting a different Islamist group). What would be the problem with those two positions? --Jayron32 05:07, 12 January 2013 (UTC)

That source only says that France is supporting the Syrian National Coalition. The SNC's president if a "moderate Islamist", but his views, although hardly enlightened by Western standards, are very different from those of Ansar Dine or al-Qaeda. Also, the SNC's vice presidents are prominent democratic activists (according to our article), one of whom is a secular feminist. The SNC is much more accurately described as an anti-Assad and pro-democracy coalition, not an Islamist coalition. --140.180.240.178 (talk) 07:17, 12 January 2013 (UTC)

This article about a recent Syria attack http://www.bbc.co.uk/news/world-middle-east-20984142 says the attack was led by the jihadist groups al-Nusra Front, Ahrar al-Sham and the Islamic Vanguard which are Al Qaeda groups, the same groups france is fighting in Mali. It's not just "some" Islamist groups they are a major force in Syria right now.--Jonharley667 (talk) 07:20, 12 January 2013 (UTC) ^{This account is a sock puppet of Wrk678 and has been blocked indefinitely}

This article http://www.brisbanetimes.com.au/world/rebels-linked-to-alqaeda-set-to-take-syrian-airbase-20130111-2cl7s.html says the the Al Nusra Front makes up 30 to 40 per cent of the rebels in all of Syria. --Jonharley667 (talk) 07:28, 12 January 2013 (UTC) ^{This account is a sock puppet of Wrk678 and has been blocked indefinitely}

The same groups France is fighting in Mali? Nonsense. The main groups who were fighting the government of Mali (until they started fighting each other) are the National Movement for the Liberation of Azawad (they want an independent homeland for the Tuareg people), and Islamist groups Ansar Dine and the Movement for Oneness and Jihad in West Africa. None of those groups have anything to do with Syria.

Right now, Northern Mali is facing this. --Guy Macon (talk) 07:40, 12 January 2013 (UTC)

My point is they are both Islamist, Al Qaeda groups, both in Mali and Syria. --Jonharley667 (talk) 08:03, 12 January 2013 (UTC) ^{This account is a sock puppet of Wrk678 and has been blocked indefinitely}

No, you specifically said that "al-Nusra Front, Ahrar al-Sham and the Islamic Vanguard are groups France is fighting in Mali." No. They aren't.

Your new, revised claim is still dead wrong. Ansar Dine is not an Al Qaeda group. They are Sufi, Al Qaeda is Sunni and thinks Suffis are heritics. The National Movement for the Liberation of Azawad is not an Al Qaeda group. They are Tuareg separatists, and Al Qaeda doesn't give a rat's ass about the Tauregs. Movement for Oneness and Jihad in West Africa did break off from Al-Qaeda in the Islamic Maghreb, (which is a purely African group) but there is no real evidence that Al-Qaeda in the Islamic Maghreb is part of Al-Qaeda, or in any way connected with any group outside of Mali and Algeria. They share a certain ideological affinity with Al-Qaeda, but in their literature and speeches they talk about getting inspiration from Seku Amadu and El Hadj Umar Tall, not from Osama bin Laden. Saying they are "the same groups" goes against all the available evidence. They don't even speak the same language! Syrians speak Arabic and Malians speak Bambara, and French.

I get a feeling that you are not very familiar with the wide variety of unconnected or loosely connected militant groups in the near east and western Africa. I hear Wikipedia has a lot of information on the subject... --Guy Macon (talk) 10:53, 12 January 2013 (UTC)

I know that science means "knowledge", which is potentially limitless in its scope, but this type of question is much better suited to the (In-)Humanities Desk, some of whose denizens never visit here. -- Jack of Oz ^[Talk] 03:32, 13 January 2013 (UTC)

In their long history with many identities on the RD, the once again blocked OP never really seemed to properly learn that there are multiple reference desks, and that not all questions belong on the science desk whether it's about Islamists rebels, hard nipples [3], video games [4], Fidel Catro travelling to the US [5] or whatever else they've asked about. They have occasionally posted to other desks but most questions seem to end up here, in fact they seem to have gotten worse over time. I can't help thinking if their interests hadn't evolved or they otherwise decided against asking such questions, they wouldn't regularly be asking about MMA/UFC fighters on the RDS like they did before [6] (I believe most of the MMA/UFC questions in the past were outside RDS). Then again if it's a choice between stuff that doesn't belong on the RDS but some other desk, or stuff that would belong if it wasn't utter crap like being immune to choking [7] I don't think either is clearly better. Nil Einne (talk) 12:11, 14 January 2013 (UTC)

You asked why France opposes the Malian Islamists but not the Syrian opposition and got plenty of good answers, despite asking on the wrong desk. It's obvious now that you're just trying to push your own views. You've come to the wrong place for that. --140.180.240.178 (talk) 12:21, 13 January 2013 (UTC)

Measuring sleep deprivation while on prescription stimulants

What methods can be used to measure short-term sleep deprivation or its effects on traffic safety, when the subject cannot fall asleep due to caffeine and/or prescription stimulants (ruling out the Epworth sleepiness scale or the multiple sleep latency test)? Any that can be self-administered? NeonMerlin 04:04, 12 January 2013 (UTC)

I suppose there are any number of tests that could be used, like saying the alphabet backwards. Normally used as a drunk driving test, you might also fail if you're sleep deprived. StuRat (talk) 04:11, 12 January 2013 (UTC)

As an example, testing the effects of sleep deprivation versus the effects of drunkenness on driving ability has been done using a "reaction time" test in some instances. You could probably download for free, or use online, any of a variety of "reaction time" type tests. They have valid uses even if they're quite primitive - in the 1990s the RAF used a very simple computer program of this nature to screen applicants for training as a pilot. --Demiurge1000 (talk) 14:04, 12 January 2013 (UTC)

Human evolution

Why did human beings, along with many other species, evolve to have males stronger than females? --Yashowardhani (talk) 08:09, 12 January 2013 (UTC)

It's by no means universal. Many insects, for example, have the reverse. However, in humans and many other mammals, pregnant females are rather incapacitated, so not much able to go hunting or fight. Thus, a gender-based separation developed, where men did most of the hunting and fighting, and women did things which could still be done while pregnant, like gathering and processing foods, making clothes, raising children, etc. With this division of labor, it makes sense for men to be bigger and stronger, since those are more important for hunting and fighting. (Also keep in mind that tens of thousands of years ago, women spent most of their short lives either pregnant or nursing.) StuRat (talk) 08:41, 12 January 2013 (UTC)

You've shown that it's not necessary for women to be strong, but is it advantageous for them to be weak? If so, why? If not, what is it that made women weak, if it wasn't natural selection? --140.180.240.178 (talk) 10:10, 12 January 2013 (UTC)

Energy cost. Male humans need to eat more calories than females. Wickwack 60.230.222.99 (talk) 10:23, 12 January 2013 (UTC)

Agree. With starvation a constant threat, there had to be a good reason to justify excess energy expenditure. StuRat (talk) 00:38, 13 January 2013 (UTC)

Any suppositions here are likely to be incomplete if not backed up by research. With that disclaimer, I'll add another factor that is likely to be a contributor to the differences between the sexes in humans, this being sexual selection (see also Sexual selection in human evolution). Just as male birds of some species display very different and gaudy plumage as a result of choice of mating partner made by the females, sexual partner selection in humans can result in such differences. Since women often get to choose their breeding partners (including quite frequently through infidelity), there is a strong selection factor based on the average female preferences. A further factor is direct competition for mates, which in humans and many other mammals favours strong men because they can beat the competition to a pulp (but more normally just send them packing). The bulk of selection in humankind did not occur under the modern state-imposed nonviolence. To some extent selection for strong women is thus absent (women are more often prizes to be won than opponents to be vanquished, and they reproduce whether they're enslaved or free). Male sexual preferences also play a role, based on the premise that the offspring of powerful men will have a greater survival probability, and powerful men get to choose their breeding partners. I consider this to be a likely explanation for the not-so-functional curves and bumps that women have, largely absent in other species. — Quondum 10:55, 12 January 2013 (UTC)

I don't consider sexual selection itself to be an answer. That is, there must be some underlying reason why human males want big breasts on their females, whereas other species don't. In this case, I believe the reason proposed for women having large breasts all the time is that it's an age marker, making it obvious when a woman is of childbearing age. (Since some women are quite short, height alone is not a good indicator.) Facial hair on males served a similar purpose. (Body hair wouldn't be as useful, after the invention of clothing.) In other species, there are color changes, etc., which serve the same function. StuRat (talk) 00:37, 13 January 2013 (UTC)

See Sexual dimorphism. Humans are at the low end of sexual dimorphism as far as primates are concerned, much more like bonobos than gorillas. This I believe is taken to mean that there is some polygamy but it is not the norm to have harems and have to defend them like gorillas do. Dmcq (talk) 13:34, 12 January 2013 (UTC)

God! Are you guys biologists? Anyway, thanks a lot for your answers. Although I have one more question- Are (human) males superior than females in intelligence as well? I read somewhere that men have larger neurons but women have more numerous neurons, so you can't really tell who's more brainy. Is that correct? --Yashowardhani (talk) 14:06, 13 January 2013 (UTC)

See the IQ section of Sex and psychology]. Have you ever won an argument with a woman ;-) Dmcq (talk) 14:43, 13 January 2013 (UTC)

I have! I recall I also once won an argument with you, although it was difficult because you weren't arguing rationally. Itsmejudith (talk) 22:45, 16 January 2013 (UTC)

Modern neurobiology thinking is that it is not the number of neurons that determines intelligence, but the number of interconnections between neurons. The size of neurons (mass or volume) seems to be unimportant.

Pure OR here, but decades of interracting with males and females, at home, office staff at work, and professionals (male and female) and managers at work has taught me that females are neither more nor less intelligent than males, but they ARE different:-

• Females often think faster than males, but they do not think as deeply, even when they are engineers or managers working on complex engineering or management questions.
• Females claim they are better at multi-tasking. They are more comfortable multi-tasking, but at the cost of not performing any particular task as well.
• Females are more comfortable following laid down rules. In a large engineering organisation, rules, guidelines, and policies must be set for staff to follow. However, no rulebook or policy document can cover all situations, as the author(s) cannot anticipate everything or predict the future. It is part of the role of profesional Engineers to recognise when given circumstances are something the rule/policy author did not anticipate or could not anticipate, and decide that an exception should be made. Females, who are otherwise very capable Engineers, are never entirely comfortable with this - they tend to follow the rules just because they are the rules, even when the outcome will be sub-optimum. I've had to council subordinate female Engineers on this - I have never needed to explain it to males.
• For males, the tendency is that outcome is important; for females the tendency is that process is important.
• Females have a different negotiating style to males. Males instinctively try to go for a win-win agreement; they try to see the other's point of view. Females tend to go for a win/lose or give/take agreement; they try to assert dominance. Males compromise to secure happiness on both sides; females compromise if and only if they want to grant a favour or make the other party feel good, and they see that as a cost or investment.
• Males are more atuned to logic; females are more atuned to who feels what emotion.

Wickwack 120.145.32.87 (talk) 16:02, 13 January 2013 (UTC)

That 2nd to last one seems exactly the reverse of what I've observed. Specifically, male salesmen often seem to try to trick me/rip me off (so they win and I lose). StuRat (talk) 17:13, 13 January 2013 (UTC)

We've all been ripped off by unethical salespersons. The role sometimes seems to require a degree of win/lose, and percentage commisions are a powerfull incentive to sell something that won't quite fill the need. Historically, most sales staff have been men, but women are moving rapidly into the role. I don't know about your area, Stu, but here, which group of sales staff are least trusted? answer - real estate salespersons. Which major product/service has the highest fraction women? answer - real estate. Which products or services are the biggest ripoff? answer - homeopathy and iridology. How many that field are men? answer - very very few. I've been in a sales role myself (selling engineering products) and would never be comfortable selling a bad or useless product. All the male sales guys I knew as colleagues were the same. Wickwack 121.215.4.48 (talk) 00:00, 14 January 2013 (UTC)

Stu, have you never accompanied your lady to a dress shop, to buy her a nice dress for her birthday. I have, a few times - this is how it works:-

My lady, to saleswoman: "I need a new dress to wear to a party, and to a wedding later on."

Saleswoman: "Well, ma'm, you've come to the right place - we have just recieved a shipment of the newest dresses. What do you have in mind?"

My lady: "I'm not sure. It needs to be dressy. Something that will look really nice."

Saleswoman, face beaming: "I have a dress here (pulling one from a rack) you'll like, please try it on." Guides my lady to a fitting room, then goes over to see who has come in the front door.

I look at a couple of other dresses on the rack. I notice the price - $329. I turn to another, more junior, salesgirl and ask "Are all the dresses on this rack the same price?"

Junior girl: "They are all the same label and should about the same - $299 to $359."

My lady comes out of the fitting room wearing the dress. Saleswoman russhes over and gushes "Gee that dress is made for you - you make it look so so nice."

I'm thinking: It makes her front look small and her arse look big. The colour does not go well with her hair and skin, and it's not cut right.

My lady looks at me with a questioning look. I say "no".

Saleswoman orders junior girl to bring me a drink.

My lady asks "how much is it?"

Saleswoman: "Oh it looks so good on you - I want you to have it. I can let you have it at a special price - $299, today only, the label is very popular. Calls over junior girl, saying to her "What you you think?". Junior girl remembers her training and smiles at my lady, saying how much the colour brings out my lady's beautiful hair.

My lady looks at me again. I again say "no.".

Saleswoman says to me "Don't you like it? You want your wife to really look her best at the party."

Me: "I don't like it. And it doesn't hang properly - it's not cut right."

Saleswoman looks startled, looks at the dress, and says: "Heavens, you are right. How silly of me - I do appologise." Then gets another dress.

Wickwack 120.145.167.213 (talk) 01:14, 14 January 2013 (UTC)

As you are still with us, I assume you decided not to tell your lady it makes her arse look big. :-) StuRat (talk) 01:44, 14 January 2013 (UTC)

Of course not. I'm not a complete idiot. Wickwack 120.145.167.213 (talk) 02:18, 14 January 2013 (UTC)

Very funny Wickwack, but let's not be stereotypical. I've myself met many salesmen who cheat costumers by such flattery, and I have a very difficult time casting them away. — Preceding unsigned comment added by Yashowardhani (talk • contribs) 07:33, 14 January 2013 (UTC)

The reason why its' funny is that we all know that's how dress shops operate. Don't forget what I said elsewhere - its not a hard division, but females tend to work certain ways, and males tend to work certain other ways. Females are not dumber or smarter than men, men are not dumber or smarter than females, but they do tend to think in different ways. Wickwack 120.145.205.197 (talk) 07:45, 14 January 2013 (UTC)

Yes, but those different ways are never so predictable. -Yashowardhani (talk) 09:14, 14 January 2013 (UTC)

I had a similar experience when buying a suit from a male salesman. He took my measurements, I told him which suit I wanted, and he got me one in what he assured me was the proper size. I know what size I am, and that was clearly too small, as I remarked both before and after I tried it on. Only after I insisted on the next size up did he admit that they were out of that size. :-) StuRat (talk) 05:34, 15 January 2013 (UTC)

Used car salesmen are the most despised salesmen here, and are almost all male. StuRat (talk) 00:47, 14 January 2013 (UTC)

Here in West Australia, used car salespersons used to be all male, and they were the most despised/least trusted after real estate salespersons. However, most of the small car yards have dissappeared. The large car yards attached to new car dealers have taken over the market. Their reputation is more important to them, as they are in it for the long haul. Their sales staff are no where near as pushy as the small yards used to be. But, they have a lot of women salespersons. Overall, I think you are right in your initial comment on salespersons, but the percentage commission drives men and women to be less ethical. Without the commission pressure, you'd see men go for win/win. Wickwack 120.145.167.213 (talk) 01:28, 14 January 2013 (UTC)

Car sales folk used to be all male because men used to be car oriented, and liked to talk about engines, compression ratios, torque curves, and such like. Western culture meant that men regarded women as not able to talk technical. But increasingly these days, men see cars the same as women do - just a means of getting from point A to point B in comfort, and don't even know how an engine works. Hence women are taking over the sales role. Wickwack 120.145.167.213 (talk) 01:38, 14 January 2013 (UTC)

I've never found a car salesman, new or used, male or female, which can answer Q's like "What does this button do ?" or "Does this car allow me to keep it on defrost or does it turn it off automatically after a few minutes ?". StuRat (talk) 01:46, 14 January 2013 (UTC)

I work with men and women, who are people, rather than males and females, which are biological specimens. And I haven't noticed anything like the marked differences that you report, Wickwack. Has it occurred to you that they may be a result of observer bias? Alternatively, the differences may be real, but socially determined. I am not aware of any reliable evidence that such differences are definitely genetically determined. AlexTiefling (talk) 16:13, 13 January 2013 (UTC)

You don't say in what field you work in. I do feel that professional engineering and engineering management tends to highlight the differences more than other types of work. I did not mean to imply the differences are marked - they a more in the way of tendecies. For instance, you will find males who will follow rules slavisly, you will find females who break rules; you will find males who think the processis more important than the outcome, especially in large organisations. However the differences, group for group are there as I described. Lastly, the differences could well be determined as much by social interaction as by sex-linked genetics, however, with modern western society becoming less divisive in what females do vs what males do, the diffrences I describe seem to be as evident as ever. On occaisons I have been the leader of a project, and announced to the team assembled for the project that I have decided that on this project we will depart from some aspect company policy for reasons 1, 2, 3 etc. The reaction from males is usually to accept it and comply with my direction, or raise an objection politely, explaining their reasons and then comply with my direction (which is entirely proper and professional). However females have raised a big stink or announced they cannot work with me - either way it is not good for them nor me nor the company. If males object, usually futher explanation will win them over; with females it's often best to just say "these are the new rules - no discussion will be entered into." Wickwack 120.145.32.87 (talk) 16:40, 13 January 2013 (UTC)

I think that the observation is correct that "the differences may be real, but socially determined." Men have generations of history behind them concerning teamwork in the workplace that women don't. I basically have physical tasks in mind. Bus stop (talk) 16:42, 13 January 2013 (UTC)

Good point. I find that the differences apply at home too, but that does not invalidate your point. Wickwack 120.145.32.87 (talk) 16:46, 13 January 2013 (UTC)

Women also needed teamwork before working outside the home, as in watching each other's children. StuRat (talk) 01:50, 14 January 2013 (UTC)

Hey, nobody told me if whether or not what I read was correct. --Yashowardhani (talk) 12:48, 15 January 2013 (UTC)

Presumably you are referring to your second question. You asked if men are more intelligent than women. The answer I gave, based on a lifetime of experience is no, but how women think is different to how men think. In the ensuing discussion here, there was debate about what the differences are, but there seems to be agreement that there are differences. Classical intelligence tests, such as Stanford-Binet, tend to return slightly better results for men. but 1) the value of such tests is disputed, 2) the difference in results is mostly likely an artifact of the design of questions, and 3) they don't measure important dimensions of intelligence, such as social intelligence. You said that you read that men have larger neurons but women have more nuerons. I answered by saying that the size of neurons is unimportant wrt intelligence, and the number of neurons is unimportant - what counts is the number of interconnections between neurons. This is made very clear by the fact that the number of neurons in an infant's brain is greater than that of an adult, but has far fewer effective connections. Adults are clearly more intelligent. So that part of your question is not relevant. The number of neurons in a human brain cannot be measured accurately, and the number probably varies as much person to person as male to female, although men have slightly larger brain volume. Depending on what book you read, the number is around 80 to 100 billion, males averaging 4% more than females, but as I said, it is quite unimportant wrt intelligence. See http://www.doctorhugo.org/brain4.html for a neat little summary. Wickwack 124.178.150.220 (talk) 15:12, 15 January 2013 (UTC)

Wicwack, your women colleagues are suspicious about why you want them to deviate from the standard engineering procedures that you were all trained in. Perhaps they suspect your motives because their intuition has allowed them to deduce that you are the kind of engineer who would make wild generalisations about them on Wikipedia. Itsmejudith (talk) 22:42, 16 January 2013 (UTC)

The projects got completed on time and on target wrt requirements anyway. Some of the women were never a problem, some were but learnt from the experience, and one left the company, which is unfortunate for both her and the company, as she was in other respects a very good Engineer. You've missed that they objected because, as they said, they saw me as breaking the rules - what was initially unsaid by them was that I took them outside their comfort zone. Nobody questioned my motives. You've also missed the fact, which I pointed out, that in the real world things crop up that were not anticipated - exceptions to the rule if you will. It IS part of the role of Engineers and engineers to recognise such events and react to them, which by definition will involve varying from standard procedure. That is part of what Professional Engineers are trained for and why they are needed. Engineering projects, in requiring deviation from standard procedures, are quite different to the OP's question, which by its' nature REQUIRES generalisation (The OP asked are men smarter than women? The answer, generallising, is no. But you will get exceptional individuals either way)

Rather than inject a degree of emotion into the discussion Judith, why not contribute constructively to the OP's question - by setting out logical argument, citing sources, or by describing experience? Why do you think various male and female engineers were allocated to my supervision on various projects likely to involve such comfort zone shifting? Wickwack 121.215.50.187 (talk) 00:43, 17 January 2013 (UTC)

A question about Ions

Hello wonderful helpers and angels :)

How could it be that some Ions are positively charged (+) or negatively charged (-) if the number of their atom's Electrons & Protons, is always the same?

In other words, if to get Pos charge we need to add protons, and to get Neg charge we need to take out electrons, how could this be even possible if their number is in all cases equal?

Please give me the simplest and shortest answer you can, thanks. — Preceding unsigned comment added by 79.180.108.146 (talk) 12:34, 12 January 2013 (UTC)

Ionization always involves the adding and removing of electrons, not protons, because the protons are bound up in the nucleus. (I'm sure someone will be along shortly to explain about nuclear processes, but we'll ignore those for now, as they're not reversible.) So an atom that becomes a positively charged ion of the same element does so by losing a number of electrons equal to the positive charge, and one that becomes a negatively charged ion does so by gaining the appropriate amount of electrons. AlexTiefling (talk) 13:01, 12 January 2013 (UTC)

(edit conflict):The article to which you link explains it all. It is not possible to make an ion (of the same element) by adding a proton. A positive ion occurs when the atom loses an electron (usually because it has one or more in an outer "orbit" not as closely attracted as those in the inner shells, though experts might quibble with my simplistic explanation). Negative ions occur when an atom gains a spare electron (usually because its outer shell has one or more electrons needed to make it complete). Dbfirs 13:05, 12 January 2013 (UTC)

well, i assume that in some cases, there is a limit to the number of atoms that could be added to an atom. thank you! — Preceding unsigned comment added by 79.180.108.146 (talk) 14:13, 12 January 2013 (UTC)

Here are the basic rules on atoms:

1) If you change the number of protons, it becomes a new element.

2) If you keep the number of protons the same, and change the number of neutrons, it becomes a different isotope of the same element (some of which are radioactive).

3) If you keep the number of protons the same, and change the number of electrons, it becomes a different ion of the same element (meaning it has a positive or negative charge).

Note that 2 and 3 are not mutually exclusive, so you can have different ions of different isotopes of the same element. StuRat (talk) 00:25, 13 January 2013 (UTC)

Science behind dry hair

Hi. I overheard some people talking about their hair. One person said their hair was very "dry" because they washed and blowdried it every day. They knew it was "dry" because if they ever let it dry (after washing) on its own, without using the hairdryer, it remained wet for hours.

Another person responded that their hair had been a similar state, but after using moisturizing shampoo and a salon hair oil treatment, their hair became less "dry" and they could prove it because if they let it dry (after washing) on its own, it became dry in half an hour.

To me it is counterintuitive that "dry" hair stays wet and moisturized hair dries quickly. I'd like to understand the science going on here - why does the hair remain wet or not? The hair article didn't help. Thanks! 184.147.123.169 (talk) 14:58, 12 January 2013 (UTC)

"Dry" hair has had its oils stripped, oils being hydrophobic, or water-repellant. Long "dry" hair then tends to retain water like wet mop strands, while moisturized hair will let water drip off freely like rain off a duck's back. μηδείς (talk) 18:57, 12 January 2013 (UTC)

Imagine a stack of thick towels. We will call these the "dry towels". Pour a few gallons of water on them and then measure how long it takes for the stack to dry.

Now imagine that you repeat the experiment, but first you soak the stack of dry towels in oil. We will call these the "Moisturized towels". Pour a few gallons of water on them (most of which beads up and rolls off) and then measure how long it takes for the stack to dry ("Dry" meaning "no water"). --Guy Macon (talk) 19:04, 12 January 2013 (UTC)

Now imagine you have to pay food-waste specialists to come haul away those ruined towels!  :) μηδείς (talk) 20:27, 12 January 2013 (UTC)

Do Identical twins have the same type of DNA and if so,why their behavior is different?

I have heard identical twins have the same type of DNA. So, if it is, why they don't have the same behavior?--Ganesh Mohan T (talk) 16:24, 12 January 2013 (UTC)

Behaviour is not determined by DNA. Roger (talk) 16:33, 12 January 2013 (UTC)

Behavior is not solely determined by DNA. (Nature versus nurture; gene–environment interaction; heritability; behavioural genetics; and especially on point, twin study and Minnesota Twin Family Study.) TenOfAllTrades(talk) 16:38, 12 January 2013 (UTC)

See the difference between wikt:determine and wikt:influence. Roger (talk) 16:48, 12 January 2013 (UTC)

As a general bit of research advice, it's not always wise to rely on an incomplete, wiki-based project to fully cover any particular topic; the breadth of a word's definition and usage often exceeds that which has made it into Wiktionary. Do you have anything to say that's actually relevant to the original poster's question? TenOfAllTrades(talk) 17:08, 12 January 2013 (UTC)

The above are right to point out that genetic determinism (in its strictest sense) is a fallacy, but it's also interesting to consider epigenetic differences. A famous study (Fraga et al., 2005) showed that epigenomes grow increasingly disparate between individuals with age, even monozygotic twins. Besides, even at the DNA level monozygotic twins may have differing copy-number variation Jebus989^✰ 17:49, 12 January 2013 (UTC)

Twins have the same DNA, meaning that aside from mutations and mitochondrial DNA, their DNA have the same sequence of base pairs. All organisms on Earth have the same "type" of DNA, meaning they use the same base pairs and have the same base-pair-to-amino-acid encoding scheme. --140.180.240.178 (talk) 20:11, 12 January 2013 (UTC)

Why would the mitochondrial DNA of (identical) twins be different (aside from mutations)? - Lindert (talk) 00:31, 13 January 2013 (UTC)

So, What really controls the behavior of an organism? Do DNA have any effect on the behavior?Ganesh Mohan T (talk) 09:19, 13 January 2013 (UTC)

See Nature versus nurture. Alansplodge (talk) 16:47, 13 January 2013 (UTC)

There's also a random factor. For example, your genetics combined with Sun exposure may determine how many freckles you get, but their exact placement is random. So, even identical twins with identical sunlight exposure would have different freckle patterns. StuRat (talk) 07:48, 14 January 2013 (UTC)

The same reason that if one twin grows up in France, they speak French while the other that grows up in England speaks English. There are many learned behaviors that people get from experience. --DHeyward (talk) 22:07, 16 January 2013 (UTC)

a wormhole is two black holes?

I'm a little bit confused about this topic.how can be a wormhole two black wholes, as it is said that if we enter one mouth of the wormhole then we come from other mouth of the wormhole.if both the mouths are black holes then how can an object entering through one can come out of other hole.because nothing can escape from black hole's attraction force, everything is attracted by it then how come any thing come out of it.my doubt is if both the mouths are black holes then both of them will attract matter and all of this will be piled up at the center then how will any thing come out? — Preceding unsigned comment added by 202.65.149.230 (talk) 17:04, 12 January 2013 (UTC)

You may wish to read white hole. Brambleclawx 19:03, 12 January 2013 (UTC)

I'm reminded of CatDog. :-) StuRat (talk) 00:11, 13 January 2013 (UTC)

Some other possibilities, besides a white hole:

1) Time travel. The mass comes out at some other place and time, perhaps the Big Bang.

2) Evaporation. Black holes do very slowly evaporate, so the mass will eventually come back out that way.

3) The mass travels to a parallel universe where it comes out in either white holes or a Big Bang there.

4) No such thing as wormholes (the mass just stays in the black hole).

Note that none of these are particularly promising for the sci-fi idea of a space ship travelling around our universe. If anything makes it back out, it's probably just subatomic particles. StuRat (talk) 00:15, 13 January 2013 (UTC)

Realistically, there is no evidence to suggest that a black hole is functionally a hole in normal terms at all. It's a singularity - a point in space with no properties except mass (and possibly rotation). Anything falling into a black hole just adds its own mass to that of the hole, which will eventually shed it again through Hawking Radiation. AlexTiefling (talk) 11:14, 13 January 2013 (UTC)

To get through the wormhole in the standard Schwarzschild black hole solution you need to travel faster than light, and if you allow that then the usual you-can't-get-out rule doesn't apply. The Kerr black hole (like the Schwarzschild but rotating) is connected internally via slower-than-light paths to both white holes and antigravity holes with negative mass (which aren't the same thing). But nobody takes any of this seriously because these aren't realistic solutions. In particular they don't have any matter in them, while real black holes are formed by the gravitational collapse of ordinary matter. -- BenRG (talk) 16:51, 14 January 2013 (UTC)

large quasar group

hi, as to the recent news on 1/11/13, im curious as to any informed opinion on the matter. How could something 4x bigger than expected, and contrary to scientifically accepted givens exist, I would appreciate any response,,thank you..--Ozzie10aaaa (talk) 19:24, 12 January 2013 (UTC)

I second the user's question, what sort of informed comment can we get toward describing this object (only the one paper?) objects similar to it, and the theories about such objects and how this one violates it? I know we have several informed people here on astronomy. Unfortunately I am not one of them. μηδείς (talk) 20:52, 12 January 2013 (UTC)

Large as this thing is - it's still only a tiny dot of light. We can't measure it directly - everything has to be very indirect. You have to use spectrometry to figure out where the brightest parts of the spectrum are - then use redshift to estimate the speed at which it is moving relative to us - then use hubble expansion to estimate the distance to the object - then (knowing the nature of the object), compare the brightness to other objects of a similar type to get an idea of size. It's very easy for one of those many assumptions to go awry - so there is always scope for some other data to come along and radically alter the results. SteveBaker (talk) 00:13, 13 January 2013 (UTC)

Here is the discovery paper, and it's pretty readable. SteveBaker is almost completely wrong, which is highly unusual for him. The LGQ is not a tiny dot of light; it actually consists of 73 quasars spread across 15 degrees of the sky. The complete 3D distribution of these quasars can be gotten just by measuring their redshifts, and at a redshift of 1.3, that's a very easy measurement by spectroscopic standards. It's true that Hubble's law (or more precisely, the Friedmann equations) are needed to convert redshift into distance, but the relevant cosmological parameters have been nailed down to within 1%, and hardly anyone believes the calculated distance could be off by a factor of 2-4.

As for the OP's question, the honest answer is that nobody knows for sure, but it seems to violate the cosmological principle. That's the whole point of the paper--if the quasar group was perfectly consistent with theory, there would be no point in publishing the paper in the first place. The paper does note, however, that similar evidence of gigaparsec structure had been found in the past: "Evidence for Gpc-scale correlations of galaxies has been presented by [...] Hutsem ́kers et al. (2005), who found that the polarisation vectors of quasars are correlated on Gpc-scales. Similarly, the existence of cosmic flows on approximately Gpc-scales (e.g. Kashlinsky et al. 2010), regardless of their cause, is itself implying that the universe is not homogeneous." There's also statistical anomalies in the cosmic microwave background--see CMB cold spot.

Medeis asked a much more complicated question, but I'll try to answer it. The cosmological principle says that the universe is homogenous and isotropic at large scales--in other words, that if you zoom out enough, it looks uniform. All the structure we see today, according to standard cosmology, comes from random temperature fluctuations in the early universe. These fluctuations, which we can see directly in the cosmic microwave background, translate to slight overdensities and underdensities of matter. The overdense regions collapse gravitationally, creating the large-scale structure of the universe. There should be a size limit to this large-scale structure, because at a certain distance from an overdense region, the gravity from that region is too weak to have much effect. The size limit is called the "End of Greatness", which is described in our article on large-scale structure, and there's abundant evidence from the CMB and from galaxy surveys that it exists. What the size limit actually is, however, is not simple to calculate, because it depends on how matter collapses gravitationally to form structure. Clowes et al. uses the results from Yadav et al., who ran a N-body simulation for the entire universe to calculate what the size limit should be if the universe were homogenous at large scales, and the result was 370 Mpc. This suggests one reason that a gigaparsec-long LGQ might be possible: the simulation is flawed. Clowes et al. discuss this in their paper: "Of course, history and, most recently, the work of Park et al. (2012) indicate that one should certainly be cautious on the question of homogeneity and the cosmological principle. The Sloan Great Wall (Gott et al. 2005) and before it, the Great Wall (Geller & Huchra 1989) — was seen as a challenge to the standard cosmology and yet Park et al. (2012) show that, in the “Horizon Run 2” concordance simulation of box-side 10 Gpc, comparable and even larger features can arise, although they are of course rare." If you were to ask for my opinion on the most likely explanation--and keep in mind I'm far from an expert--I'd say the simulation's assumptions were too restrictive, and a more realistic simulation, combined with more rigorous statistical analysis (the Clowes et al. paper has no statistical analysis at all), will show the huge-LGQ does not violate the cosmological principle. --140.180.240.178 (talk) 02:01, 13 January 2013 (UTC)

That was very clear, IP 140. I wish I had realized that this is meant to be a violation of "the cosmological principle" which is simply a heuristic, and in no way any sort of law of physics, as opposed to an actual violation of cosmological principles. The report of that latter in the press made it sound like some known physical law would constrain "structures" of a certain size to be physically impossible due to physical laws, not just statistically unlikely pending actual observation. μηδείς (talk) 03:03, 13 January 2013 (UTC)

thank you for your very good explanation,,,,,,,,,,,"TO IMAGINE IS EVERYTHING"-Albert Einstein..--Ozzie10aaaa (talk) 15:30, 13 January 2013 (UTC)

Oriole question

Does anyone happen to know exactly how does the Northern Oriole carve up a Monarch butterfly prior to eating it? Does it just tear out and consume the insides while leaving the rest of the bug more-or-less intact, or does it first rip off (and discard) the bug's wings and/or head as well? Also, do orioles make the Monarch a regular part of their diet, or do they only eat it when there's nothing else left to eat? (And while we're at it, after consuming a Monarch, does the Northern Oriole tend to have a craving for something sweet to get rid of the awful taste?) 24.23.196.85 (talk) 21:28, 12 January 2013 (UTC)

They cut it with teen-weeny knife and fork, and drench it with ketchup. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:02, 12 January 2013 (UTC)

No, seriously! It says in the article on the Monarch butterfly: "Overwintering monarchs in Mexico are often preyed upon by black-headed grosbeaks, which are immune to that toxin. Other birds, such as orioles and jays, have learned to eat only the thoracic muscles and abdominal contents because these contain less poison than the rest of the body." (Emphasis mine.) 24.23.196.85 (talk) 22:07, 12 January 2013 (UTC)

I remember having seen movies (real moving projected film that occasionally burst into flame) in elementary school of birds tearing the wings off butterflies before eating them. They didn't linger on which part of the innards, though. μηδείς (talk) 03:39, 13 January 2013 (UTC)

Thanks! You've just confirmed my original hunch -- that the bird would first rip the wings off and discard them, because those are the worst-tasting parts of all (in the case of the Monarch and some others, in any case). But will birds like the Northern Oriole or the American Robin eat a Monarch at all if there are other insects available? 24.23.196.85 (talk) 04:15, 13 January 2013 (UTC)

Black swallow-wort

It says in the article on Black swallow-wort that an infestation of this weed can cause a decrease in bird population. My question is, how? Have they figured out any kind of causative mechanism, or is there only a positive correlation at this time? 24.23.196.85 (talk) 22:00, 12 January 2013 (UTC)

Well, the article says that it's this plant is an invasive species that crowds out other plants. That would obviously reduce populations of insects and other animals that have evolved to live in the crowded-out plants - and that in turn will reduce populations of higher species that pray upon them. If the plant crowds out grasses (as our article kinda suggests) - then maybe there could maybe be no grasshoppers left there either. So birds that like to eat grasshoppers will be forced to go elsewhere. I don't know whether it's grasses, grasshoppers and grasshopper-eating-birds that are being lost in this case - but you can be sure there will be some other food-chain that's getting broken here. Worse still, with an invasive plant species, the insects that have evolved to live on those plants probably didn't get introduced along with them - so to there may not be so many insects of any kind there - and that would reduce the population of insectivorous birds even if they are able to eat other kinds of insect. SteveBaker (talk) 00:30, 13 January 2013 (UTC)

Thanks! So the most likely mechanism is simple food deprivation, right? 24.23.196.85 (talk) 04:17, 13 January 2013 (UTC)

That seems most likely - but I have no proof of that. There are other possibilities - perhaps the birds are specifically camoflaged to hide in the original type of vegetation - or maybe they have specialised adaptations for perching or nesting in the branches of the plant species that's being forced out of that area. That seems less likely - but I couldn't find any studies to show that in this case. SteveBaker (talk) 13:55, 14 January 2013 (UTC)

Mottaphobia

Is mottaphobia (what the hell, no article even though Nicole Kidman suffers from this condition?) more common in men or in women? 24.23.196.85 (talk) 22:14, 12 January 2013 (UTC)

Try Mottephobia - though it just redirects a short section in Moth. AndrewWTaylor (talk) 22:19, 12 January 2013 (UTC)

Thanks! So, does anyone happen to know whether it's more common in men or women? 24.23.196.85 (talk) 22:25, 12 January 2013 (UTC)

Phobias aren't really broken down into fears of each specific kinds of object - words like "mottaphobia" are largely made up on the spot by who-knows-who. As far as science is concerned, phobias are really only split into three kinds (irrational fears relating to people and social situations, agoraphobia and a fear of things like animals). The latter is called "a specific phobia" - and that's what this irrational fear of moths would come under. Our article on "specific phobias" says that "women are twice as likely to suffer from specific phobias as men". Fear of moths is obviously just a special case of Entomophobia...and our article on that subject points out that all "specific" phobias have similar causes. So I strongly believe that your answer is "women" - by about two to one. SteveBaker (talk) 00:14, 13 January 2013 (UTC)

Thanks! That's just what I wanted to hear.  :-) 24.23.196.85 (talk) 02:47, 13 January 2013 (UTC)

Our phobia article seems to back up Steve, but it seems very odd to me that claustrophobia is not mentioned here. I would think that would be by far the most common one (article says 5-7% incidence). And agoraphobia is called out separately? I thought agoraphobia was considered a subset of claustrophobia (the fear is not of open spaces, as often described, but rather of being hemmed in by a crowd and unable to escape). Maybe they're doing the reverse, counting claustrophobia as a subset of agoraphobia? --Trovatore (talk) 07:22, 13 January 2013 (UTC)

I thought agoraphobia was an umbrella word that meant insuperable anxiety/panic in a public place. In my experience of treating people with this particular phobic condition the level of anxiety usually relates to the person's perceived distance to safety, most commonly their home. As the condition presents in subtly different ways with distinct problem areas for different individuals I cannot understand the value of all this specific defining. Richard Avery (talk) 08:35, 13 January 2013 (UTC)

Do I understand that you're a psychiatrist or clinical psychologist? If so you'd know much better than I would. Can you explain the apparent omission of claustrophobia from the tripartite schema Steve reports, which does seem to correspond to what our article says? I don't see claustrophobia as either one relating to people and social situations, or one relating to things like animals. If anything, I'd have thought agoraphobia would be "relating to people and social situations". --Trovatore (talk) 09:05, 13 January 2013 (UTC)

I was a mental health nurse in my younger days and discovered that it does not require high powered techniques to help anyone to come to terms with a phobia. I have no reference for the scheme to which you refer but I have seen so much written about phobias and their cause and cure. Guess what? Much of it was rubbish, exaggeration or journalistic puff. OR warning! From my experience of both carrying out desensitisation of phobic people and discussing cases with colleagues, the classification has less to do with the therapy strategy than the patient's history and subjective response. If academics or others want to spend time naming different classes of phobias and finding names for specific phobias (some of which are either non-existent, unique or as rare as chickens teeth) then good karma. But I always preferred to concentrate on the individual client and their life. Best. Richard Avery (talk) 15:22, 13 January 2013 (UTC)

OK, that all sounds fine, and I have a general suspicion that there's plenty of nonsense in the DSM anyway (or that it's working from a fundamentally flawed paradigm). Still, it seems to me there's an obvious question here that hasn't been answered, and I'd be interested to know the answer. Accepting for the sake of argument the DSM's paradigm, where does claustrophobia fit? --Trovatore (talk) 20:34, 13 January 2013 (UTC)

I don't see an issue. Specific phobia lists four sub-categories and one "catch-all": Animal type, Natural environment type, Situational type, Blood/injection/injury type...and "Other" (for fear of clowns and super-heroes for example). Claustrophobia is listed as a "Situational type specific phobia"...which seems pretty reasonable.

However, that brings up a deeper issue: According to specific phobia, all specific phobias taken together have a "one-year prevalence of 4.4% in the USA" - yet our claustrophobia article says that "5–7% of the world population is affected by [claustrophobia]". So either one of these numbers is wrong - or the difference between "one year prevalence" and "is affected by" is somehow statistically relevant - or for some bizarre reason, Americans are vastly less concerned about being confined in small places than humanity in general! SteveBaker (talk) 13:51, 14 January 2013 (UTC)

Hmm, to me it seems a bit weird that agoraphobia would be called out separately, given all this open space to itself, but claustrophobia would be stuck down inside this tiny tight little location surrounded by lots of other phobias, hemming it in and suffocating it. --Trovatore (talk) 23:01, 14 January 2013 (UTC)

melting point

why melting point of magnesium show a deviation from regular trend in group iiA? — Preceding unsigned comment added by 119.160.126.98 (talk) 23:06, 12 January 2013 (UTC)

This sounds like a homework question. Can you give a link to that groups' article at wikipedia, so we know you have read what we have available? μηδείς (talk) 00:01, 13 January 2013 (UTC)