Derivatives of fluctuations about a condensate

Question:
Firstly I am not sure as to whether I am using the word "condensate" in the right context. In QFT contexts I think I see it getting used to mean the space-time independent solution which would solve the Euler-Lagrange equations of the action that would sit in the exponent in the path-integral - which in general might be different from the classical action. I would like to know why are these kinds of solutions so important - because this is picking out some special configurations among the entire space of classical solutions which would in general include non-trivially dynamical solutions.
Now when one is doing a "small" fluctuation about the condensate and integrating out degrees of freedom to get an effective action for one of the fluctuation variables then there are two issues which confuse me -

In multi component fields (like say complex ones which can be thought of as the modulus and the phase) what drives the choice as to which fluctuation is to be integrated out? (..in the complex case I guess in general people talk to the effective action for the phase fluctuation..)
What is most confusing to me is to understand how to determine whether the space-time derivatives of the fluctuations are big or small. If one is doing the calculation to say second order then does one keep the products and squares of the derivatives of the fluctuation at the same level of perturbation as the squares and products of the fluctuation themselves? I can't see a natural scale for the derivatives of the fluctuations to which I can compare the derivatives to decide whether they are large or small.
Comment: I don't quite understand what you're asking here. Can you give a specific example?
Comment: @Squark May be you can consider how the effective field theory for the phase variable of a superfluid is derived starting from a lambda-phi-four theory with chemical potential - or in other words the theory of bosons interacting with a contact potential with a finite scattering length.
Answer: The condensate state is not just some solution of the classical equations of motion. It is the one which has the lowest energy. Since bosons like to be in the same quantum state, at low temperature they macroscopically occupy this lowest state. This is know as formation of the condensate.
The condensate wave-function is rigid in the sense that one needs some macroscopic amount of energy for even a small change of its modulus. However, it cost very little to disturb its phase. Thus at low energies it is natural to construct the effective theory of the phase variations (Goldstone bosons). Usually one integrates out the fluctuations of the gapped modes which leads to a local action of Goldstones only. In a conventional superconductor, for example, one would integrate out the fermions (which are gapped around the Fermi surface) and the fluctuations of the modulus of the condensate.
I think there is no unique way how to assign the smallness order to different spatial and temporal derivatives of the Goldtones. In other words, there is an ambiguity in the choice of power counting for the given effective theory. The power-counting scheme determines which energy and momentum regime the effective theory is applicable to. As far as I understand, however, Gaussian formula allows to integrate out any action quadratic in the gapped fluctuations, so this can be done exactly.


Crazyhouse Chess: Playing with a real board and overall popularity?

Question: Played a decent amount of bughouse but only started with crazyhouse a month or less ago. Although on the surface very similar games, I would say they are fundamentally different because there is no partner and so crazyhouse is "deterministic." I think that bughouse must be more popular if only because all that is required to play are two boards and two standard sets whereas crazyhouse is much better suited to online (I guess you could have bicolored pieces to play live.) So is crazyhouse catching on at all? Has anyone seen a set that would allow playing live? (I note there is not yet a tag for crazyhouse.)
Comment: Haha I would think bughouse chess is more skill and coordination reliant.  Crazy house is really just planning forward to get the pieces you need for a win
Comment: @QuIcKmAtHs: Bughouse has a lot of skill but also, at least if both players on a team are not extremely good and coordinate well, a lot of luck. I would say that cz requires as much skill as standard chess plus is far less understood. probably engines are unbeatable but in bughouse, not yet i don't think, at least not with human+engine team.
Comment: Actually there's quite a lot of crazyhouse questions here. I've created a tag and attached it to some of them
Answer: Very boring answer: when I was at the university, we used to play it on a real board with two sets of pieces. Whenever you take a piece, you exchange it with one of the correct color.
Comment: Interesting, kind of hard to not make mistakes I guess but it would work. Also, maybe pieces that could be flipped, just tiles with images of pieces.


When self teaching, should I learn set theory before continuing ap calculus?

Question: I am studying ap calculus now, before I move onto differential equations etc., but the thing I am unsure of is, should I learn set theory before continuing on my ap calculus sections?
Comment: A question: Mathematicians use the phrase "set theory" to describe a topic closely tied to mathematical logic. I could easily see someone in high school (you mention AP Calc) using this phrase to refer to open and closed intervals. The latter is contained in the former, but is more elementary and applicable to calculus. Which is meant?
Comment: Related https://math.stackexchange.com/questions/617625/on-familiarity-or-how-to-avoid-going-down-the-math-rabbit-hole
Answer: Short answer: No.
If you really want to know a little bit about sets, the first section of Book of Proof or Applied Discrete Structures would more than suffice for the purposes of most collegiate level courses.  (You'll want more of them for courses involving proof, of course, but no more set theory.)  Especially the first is quite suitable for self study.
But while there are some basic calculus arguments (especially once you start looking at vectors and/or parametric things) which can involve sets a bit, if you are studying on your own, no need to complicate matters by studying them separately.  Whatever calculus text/resource you are using should have enough background to make progress - and if it doesn't, find another one.  This website has several English-language open access texts, one of which should suffice for your needs.
Comment: Perhaps some questions are more appropriate for other sites; they do get picky here, though not as bad as editors on Wikipedia!  Don't make an edit there unless you want a fight :)
Comment: thanks sorry If I am being mean kcrisman I like this site gives me quick answers fast sometimes, just I came here to learn things I did not do well in school, all people do is close my questions and do not realise were from all over the world here from different back grounds and all different, and they never give me a chance thanks for the last comment by the way I am trying my best and I do like to help people the best I can. Not all of us are foreigners living in the country I never went to a grammar school and not all of us was tought grammar the same way.
Comment: Sorry Kcrisman for being immature and mean the other day Sometime things get frustrating when you try to hard, its not like its to hard I mean I guess with everything happening in life I guess one has to let of steam. All I meant is I just like to help on these sites and I don`t mean to be mean and say things in anger like that.
Comment: No problem.  I think that one of the issues with open resources (not just this, but including open source software, etc.) is that there are often so many people contributing that when someone doesn't contribute right away it feels personal.


Recruiter hasn't gotten back to me after requesting my availability for an interview

Question: A little over a week ago, I received an email from a recruiter requesting my availability for an interview. I responded within a few hours and have still not received anything to date. I even sent a follow-up email. Am I out of luck? And in the event that they did find a different candidate, is it normal for them to not email me back saying so?
Answer: If they want you , they will chase you or they will dump you like no tomorrow. That's the norm. In short , he is not chasing you. SO there must be a reason which only he knows. DO not put your expectations on someone just because they asked for something. Nothing is sure unless you sign on the dotted line. Keep looking and forget this. You will get used to it
Comment: Pretty much this. I've had recruiters take weeks before giving a single reply. However after they ask for availability I've always had replies within 1 or 2 days to a max of 1 week. The ones that didn't reply within that time either never replied again or said the position was filled.
Comment: Have to disagree slightly. Recruiters are humans too. No harm in giving them a call and seeing what's up. It'll keep you in their minds which is only good, even if this opportunity is gone it might make them more likely to think of you for the next one.
Comment: @colmde I was thinking about giving her a call today. What would a standard followup phonecall look like without sounding too pushy?


Why do modern aircraft have a slope on top of the airfoil?

Question: I recently learned that the pressure on the bottom of the wing is increased, and air moves faster on the bottom part of the wing. The speed of the air on top of the wing is not increased. So I am confused about what is the point of the slope on top of the airfoil. The Wright brothers' airfoil was flat, but still had the slight slope to it, and now modern aircraft have a huge slope to them. So what is the reason for the slope?
Comment: Hi Ethan.  You should know by now that this is not how wings work.  You have taken part in enough Q&As on here to know that, for example, [this one](http://aviation.stackexchange.com/questions/21664/how-complete-is-our-understanding-of-lift/21685#21685).
Comment: To understand how a wing maintains the aircraft airborne, in addition of the multiple answers you have got on this site, you may read the full explanation [here](http://www.av8n.com/how/htm/airfoils.html). In particular you should first understand [this image](http://www.av8n.com/how/img48/3v.png): The same wing, on the top it doesn't produce lift, on the bottom it produces lift because air is deflected downward by the wing. Read it until you understand most of it, as other details are then explained from the assumption you understand this important basis.
Answer: First of all, wherever you learned that, "...the pressure on the bottom of the wing is increased, and air moves faster on the bottom part of the wing. The speed of the air on top of the wing is not increased." It is wrong, and citations would be useful, if only to educate the owner of that website.A wing provides lift by imparting momentum to the air through which it passes equal to the airplane's weight. If the wing is cambered, it imparts more acceleration to the air through which it passes. (i.e. the air coming off the trailing edge has a faster downward velocity than compared to a non-cambered airfoil of equal area), thus making the wing more efficient for its area. It also affects things like stall speed.
Comment: " imparting momentum to the air through which it passes equal to the airplane's weight" That's not possible. The units of momentum are mass-times-velocity and the units of weight are mass-times-acceleration.
Answer: The slope (known as the camber) is for better stalling characteristics so that the turbulent flow separates from the airfoil slowly instead of suddenly because the curve allows the air more surface to stick on at the AoA increases to a stall.
This stall diagram shows how the cambered wing performs in a stall:

Image Source
Also, according to the gas laws, the air in higher pressure moves slower than air in low pressure. (P1*V1 = P2*V2) The air on the upper surface does move faster at higher AoAs due to the lower pressure created by the AoA.
Answer: You are wrong about the air under the wing travelling faster. It is the air travelling over the top of the wing that is faster.
The "slope" is actually called Camber. Camber makes the air flowing over the wing change direction and this causes low pressure and that results in lift.

Comment: The theory of equal transit time has been busted for quite some time. https://en.wikipedia.org/wiki/Lift_(force)#False_explanation_based_on_equal_transit-time
Comment: There is no reason why the air flowing over the top of the wing has to "join up" with the air that passed under it. In fact, the airflow over the top gets to the trailing edge before the air going under the wing. Please see http://www.av8n.com/how/htm/airfoils.html#sec-airplane-air.
Comment: @Simon True but it is still widely taught and even appears in some countries syllabi IIRC. It's a very common misconception that sparked the question in the first place and an answer like this one would be good if it explained such.
Comment: Nasa says: This is [an incorrect theory](https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html).
Comment: Also, the aerofoil in the diagram doesn't actually seem to be generating any lift since there's no reaction on the air mass.
Comment: I edited my answer to remove the "join up" statement.


Can my wife travel to the UK with me?

Question: Me and my fiance just left the Uk 2 weeks ago after staying for 6 months. We rented a place for 6 months in both our names. We are about to marry within the week in Germany where I am a citizen. She is from the USA. We want to then go back to the UK after we are wed and have all the official documents etc. I don't need a visa to visit the UK but will she? Or is proof of our marriage and her passport sufficient enough to at least let us both in without a problem.
Comment: For your wife, attempting such a rapid return visa-free after completing the maximum permitted stay as a tourist may be a red flag at the border. She should apply for a EEA family permit, your marriage certificate alone isn't sufficient https://www.gov.uk/family-permit
Comment: Yes - at least until March 29. :)
Comment: Are you working or studying in the UK? What is the purpose of your return visit and how long do you intend to stay? https://www.gov.uk/check-uk-visa/y/usa
Comment: Im not currently working there. However I have been thinking of moving there because my wife loves it. For now we just want to visit for a while longer and explore of possibility of staying there without the intention of actually staying there.
Comment: With an EEA permit would she be allowed to go with me, then?
Comment: She does not need an EEA family permit to benefit from freedom of movement.
Answer: The other (now deleted) answer was wrong.  Your wife can benefit from free movement even without an EEA family permit.  The UK's implementing regulations are the Immigration (European Economic Area) Regulations 2016.
Regulation 7 defines "family member" to include a spouse.  Regulation 11(2)(b) is perhaps the reason for the assertion in the other answer that your wife needs an EEA family permit to benefit from free movement:

(2) A person who is not an EEA national must be admitted to the United Kingdom if that person is—
(b) a family member of an EEA national, a family member who has retained the right of residence, a person who meets the criteria in paragraph (5) or a person with a right of permanent residence under regulation 15 and produces on arrival—
(i) a valid passport; and
(ii) a valid EEA family permit, residence card, derivative residence card or permanent residence card.

However, that conclusion overlooks regulation 11(4), in particular 11(4)(b):

(4) Before an immigration officer refuses admission to the United Kingdom to a person under this regulation because the person does not produce on arrival a document mentioned in paragraph (1) or (2), the immigration officer must provide every reasonable opportunity for the document to be obtained by, or brought to, the person or allow the person to prove by other means that the person is—
…
(b) a family member of an EEA national with a right to accompany that EEA national or join that EEA national in the United Kingdom;
…

The critical language there is, of course, "allow the person to prove by other means."  To do that, you should bring your marriage certificate and any other evidence that you might submit with an EEA family permit application.  If you or your wife are inclined to worry or stress, it might be a good idea to apply for the EEA family permit ahead of time even though she doesn't need it.
The other answer asserted incorrectly that your wife would be bound by the immigration rules without a family permit.  But regulations 13 through 15, which concern the right of residence, do not make any mention of the EEA family permit.
Furthermore, if your wife should be admitted with a stamp saying "leave to enter for six months, employment and recourse to public funds prohibited" then she should take note of Schedule 3, paragraph 1, which says that the restrictions imposed by that stamp do not have effect while she is in the UK with you:

Leave under the 1971 Act

Where a person has leave to enter or remain under the 1971 Act which is subject to conditions and that person also has a right to reside under these Regulations, those conditions do not have effect for as long as the person has that right to reside.
Comment: @Fattie there are accounts on this site (unfortunately, probably mostly only in the unsearchable comments) of people who have been denied EEA family permits subsequently traveling to the border without one and then being admitted by immigration officers as family of EEA nationals.  In one case, the officer even expressed surprise that the EEA family permit application had been denied.  So it seems that UK immigration authorities do indeed observe 11(4)(b).
Comment: But "law" has no connection, at all, in anyway, to what happens at borders.

Can my wife travel to the UK with me?


When is there Kaddish after a shiur?

Question: When do you say Kaddish Derabanan after a shiur? What are the requirements for this Kaddish?
Comment: One of the requirements is for there to be a minyan present.  I'm not sure if this is obvious, but it should probably be stated nevertheless.
Answer: R' Scheinberg said kaddish derabbanan after every shiur, since there was Torah shebaal pe berabim (which makes more sense than saying kaddish after "korbanos", pitum haketores and bame madlikin which we just daven off).
Comment: is the parenthetical note yours or R' Scheinberg's?
Comment: It is mine.  For the record, my answer is based on personal experience (though I can't remember if he said kaddish after mishmar shailos).
Answer: The following is taken from the sefer הקדיש here:

It is called Kaddish D'Rabanan because it was instituted to be said after learning Torah Sheba'al Peh which was transmitted to the Rabbis. (כנה"ג א"ח ס' קנח)
And this is what the Rambam says: Whenever there are ten or more Jews who are involved in learning Torah Sheba'al Peh, even Midrashim or Agados, when they finish one of them says standing up Kaddish D'Rabanan. (משנה תורה, סדר התפילה ל)
But only if some Aggada is said afterwards, because this Kaddish was mainly instituted for words of Aggada, and so the custom is to say after Pirkei Avos and במה מדליקין either ר' חנניא בו עקשיא or א"ר חנניא ת"ח וכו' in order that the Kaddish goes on the Aggada. (ש"ע ס' נד, מ"א, באה"ט)
And in a similar fashion even after learning Gemara or Zohar. (קשר גודל ס' ח)

The halachos of Kaddish D'Rabanan are mentioned in the Mishnah Berura in סימן נ"ד, ס"ק ט.
Comment: Personally, this is a much more thorough answer than the accepted one.
Answer: I heard from Rav Ben Haim that when ten study it is said. Additionally the Chacham is to say the Kaddish.
Answer: Many require that the shiur include words of aggadah, i.e. homiletic teachings on pesukim from Tanach. Others say kaddish after any public Torah study.
To fulfill all opinions, some congregations have the speaker say the last mishnah in Tractate Makkos (quoted below) after the shiur, so kaddish should definitely be said.
"Rabbi Chananya ben (son of) Akashya said: The Holy One, blessed be He, wanted to give Israel merit; therefore He gave them Torah and mitzvos (commandments) in abundance, as it is written: 'G-d wanted, for its [Israel's] righteousness, to make the Torah great and mighty' (Isaiah 42:21)."
Comment: Does he say that Mishna or teach that Mishna?
Comment: How would that accomplish anything if no one learned anything?
Comment: There are many levels of learning. Hearing a few words and kind-of understanding them is a type of learning, even if it isn't on the deepest level.
Comment: Usually just rattle it off.
Answer: What no one seems to mention is if the minyan have also to partake of the shiur. In many shuls after korbonus they have to wait for minyan and then they say kaddish immediately. Even if the chazan  does say some 'agada' no one usually can hear it and certainly not understand it.
Many people also dont listen to kaddish and daven away only answering the amen. This is really a kaddish l'vatolo and best left unsaid.
Comment: This answer could be greatly improved if sources would be provided to support the claims you make.

When is there Kaddish after a shiur?


How to find out the number of edited posts?

Question: Is there any way I can find out the number of posts I have edited? I can not find it in my profile page. I think it is good to have a counter similar to votes/badges counters.
Answer: At the moment, there is no way to tell how many edits you've made. There was a question over on Meta Stack Overflow about this back in July 2009 which pretty much says the same thing.
Jeff seemed to hint at some kind of visible counter in his answer to that question, but enough time has passed that I suspect they've forgotten all about it, which is unfortunate.
There might be some queries over on data explorer, but they should only be used as a guideline as the data is not live. Also, they might give you inflated edit counts as they count retags which don't count towards editor badges.
Comment: The queries only show if you were the *last* editor of the post, so if anyone else has edited after you it doesn't get counted.
Answer: As Ben said the data at our Data explorer is not live, but in so far that it is up to date you can use this query.


circles detected inconsistent in still video in opencv

Question: I was wondering what the cause is for circles to be detected sometimes and not other times in a still video where the circles dont move. Is it to do with quality of video?
Answer: Probably - it depends on the method you are using to search for them.
The most common problem is differences in lighting, your eyes don't notice a gradual chnage in background but any algorithm that is looking for a certain signal level is very sensitive to even lighting unless you take steps to adjust for it.


Moving AppData folder causes programs to "forget" every restart - Windows 8.1

Question: The other week my boot drive was getting full, largely due to the C:\Users\me\AppData folder (this is in Windows 8.1).  I moved the folder to D:\AppData and created a symlink from C:\Users\me\AppData to D:\AppData, as has been described online.  Later, I upgraded my boot drive to something bigger and decided to move my AppData folder back.  I deleted the symlink and cut and paste the AppData folder back to its original location, then restarted.
Everything is okay, except programs that rely on certain information in the AppData folder seem to be "forgetful" now.  For example, every time I reboot, Skype asks for my login credentials, even though I have "Sign Me In When Skype Starts" checked.  Dropbox behaves similarly, and every time I reboot it asks me to login and setup my Dropbox folder.  Outlook also is being forgetful, and every time I reboot I have to enter all the passwords to my email accounts.  Etc...
After looking online for a solution, I verified that two registry keys indeed have the correct locations for %APPDATA% (I think -- C:\Users\me\AppData\Roaming).   So this wasn't the issue.  Getting more aggressive, I also tried a Windows "upgrade" (8.1->8.1) to try to refresh the OS, but this didn't help either.
I'm at a loss and would really appreciate suggestions for how to solve this issue (without doing a clean Windows install of course).  Thanks very much!
edit/update I thought I would add that I also tried reinstalling some of the offending programs.  Even after the programs were cleanly reinstalled, they still have this same issue.  Thanks for any suggestions!
Answer: You may consider create a symlink from D:\AppData to C:\Users\me\AppData, in case that your programs have remembered that.
However, I'm not sure if it will helps... Just give it a try.
Comment: I just tried this, and unfortunately, there wasn't any change (the programs are still forgetful).  I appreciate your suggestion, though!  Hoping the answer is out there...


Old songs not showing up on my new iPhone.

Question: I recently lost my iPhone 4 so I went and bought a new iPhone 4s. I set up my new phone with the same iTunes ID and password that I have always used. I soon realized that whatever songs I had bought on my old phone were not on my new phone. How do I get those songs back? I thought I had subscribed to the cloud but apparently that didn't include my music? All of my old contacts and pictures showed up on my phone but the only music I could get was what was on my computer. Help please! I have quit a few songs missing!
Answer: I don't believe purchased music is automatically downloaded to a new device, since you might not want all of your music on all of your devices. On your new phone, just go to iTunes Store → More → Purchased → Music and you can re-download everything there.
Answer: If you've purchased the songs through itunes they should still be available in your purchases. Try redownloading them on your computer and syncing them with your phone that way.
Answer: If you have the songs downloaded on your PC you can re-add them to the iTunes library then sync them with your iPhone but if you don't have them just  go to iTunes and press on iStore go to your purchases and just download them again


changed taps and now there's no hot water

Question: We live in a detached bungalow with a combi boiler. We changed the bath and basin taps in the bathroom when we turned the water back on there's no hot water in the bathroom and no water at all in the kitchen!!!!!! can anyone help
Comment: Could debris have been dislodged during your work, plugging the valves or faucet aerators?
Comment: If you turn just the hot water on when standing at the bathroom sink what happens?
Answer: Odds seem high that you didn't actually turn the water back on correctly, since the taps in the bath were what you worked on and the kitchen now doesn't get water which cannot be caused by the bath taps - but can be caused by not opening valves after closing them to work on the bath taps. Impossible to provide any more specific hint from afar, but follow the waterlines and recheck all the valves.
I suppose if the new taps were soldered on and you really went overboard with excess solder you might have plugged the pipes, but that's really reaching for a cause (i.e., seems not very likely .vs. just closing a valve you thought you were opening, or the like.)
Answer: Could it be an airlock? Try opening all the taps in the house until they all run freely.
(possibly not all the way, as overwhelming the incoming supply would be counterproductive).
Do you know what sort of water layout you have? As you are referring to "taps" then I would guess a typical UK layout with a cold-water header tank that feeds the hot system that may also feed some cold taps. Typically any drinking water (kitchen and bathroom sink) will be plumbed directly to the mains and things like showers and toilets to the tank supply.
So, I suspect that you may have turned on the main supply but for whatever reason the tank supply is off. Either a stop valve you forgot, or a plugged outlet, or maybe the ball-valve in the tank has stuck. (easy to check)


How did the animosity between Loki and Heimdal start?

Question: I'll admit my Norse mythology is rather rusty, but I do recall after an incident these two particular gods saw each other as mortal enemies and would eventually kill each other at Ragnarok. What was it that turned them against one another (I vaguely remember a story where Heimdal caught Loki stealing a piece of jewelry from Freya and kicked his ass over it but the details have eluded me)?
Answer: You are thinking about a story referenced in the Húsdrápa, which Snorri excerpted in his Edda. It plays out more or less as you described, except Heimdall does not catch Loki in the act, but is asked by Freya to retrieve Brisingamen.  The only detail to add was that evidently Heimdall and Loki fought as seals. That is really all we know about it.
Further than this, as have already been noted, Loki and Heimdall will fight and kill eachother at Ragnarök. They also interact in the Lokasenna, a poem where Loki shows up at a party and insults the other gods. Heimdall does not seem to be under more fire than his fellow gods.
Answer: I don't think it was as much Loki doing anything to Heimdallr in particular as much as it was the fact Loki betrayed all the Aesir when he orchestrating Baldur's death. It is this reason that Loki was imprisoned to begin with.
It is prophesied that, come Ragnarok, Loki will escape from his bonds and join forces with the Giants against the Gods. After that, he runs into Heimdallr and the two mortally wound each other.
Basically, Loki killed Heimdallr's friend and then allied himself with Heimdallr's enemies.
Answer: Husdrapa, a poem by Ulf Uggason, deals with several mythological stories, including a battle between Loki and Heimdall. Arthur Brodeur's translation:

The famed rain-bow's defender,
  Ready in wisdom, striveth
  At Singasteinn with Loki,
  The son of mothers eight and one,
  Mighty in wrath, possesses
  The Stone ere Loki cometh:
  I make known songs of praise.

While it does say that Loki fought Heimdall it doesn't mention Freyja or indeed Brisingamen. Brodeur's translation refers to the object they fought over as a "stone" but other translations give it as "sea-kidney" (Faulkes) or "magic stone" (Wikipedia).
Snorri Sturluson's Prose Edda identifies it as Brisingamen. From his list of names for Heimdall:

He is also the visitor to Vagasker and Singastein; on that occasion he
  contended with Loki for the Brisingamen... Ulf Uggason composed a long
  passage in Husdrapa based on this story, and it is mentioned there
  that they fought in the form of seals. (Faulkes' translation: 76)

This in turn is often linked to the 13th century story Sorla thattr which describes how Odin got Loki to steal Freyja's necklace, so as to blackmail her into starting a war for him.
Answer: A simpler explanation is that Loki - 'Lopt', or 'fire' - is the deadly enemy of the watchman, of whom Heimdall is the archetype; that they were to be deadly enemies was practically a requirement, and so a reason must be supplied by the story-teller for their personifications to hate each other.  In the end, the fire gets the fireman, and vice-versa.
Comment: The idea of Loki as a fire god (even as he appears right next to an actual personification of fire) is no longer considered to have any merit. See here: https://mythology.stackexchange.com/questions/748/was-loki-originally-a-fire-god for a quick overview.
Comment: I don't agree with those who consider such, however well-educated they are (as Simek and Lindow clearly must be), as there is a distinct difference between the oft-useful sometimes-dangerous Loki-of-fire, that which we use in our homes, and the uncontrolled, naught-but-devastation Logi-of-fire, the wildfire that consumes not only the food but the trencher as well.


juju bootstrap key error?

Question: I followed the guides the best as i could. there is some information missing like do as root or as regular user ..formatting, quotes no quotes..what the password or paraphrase for ssh should be ..couple other trivial things. that im sure add up to where im at (stuck!)
so i have a working mass server on mx-nas-01 and 3 nodes and have been trying to get juju to start. I have tried this as both root and my regular account, sudo no-sudo and here is the output i get from juju bootstrap (however i try it)
I don't know if this could be a host,domain,account issue or what i will mention i did have to shut off my dhcp server and install masq (all defaults) to get the maas pxe to work for the nodes
mxdog@mx-nas-01:/$ juju bootstrap
Traceback (most recent call last):
  File "/usr/bin/juju", line 8, in <module>
    main(sys.argv[1:])
  File "/usr/lib/python2.7/dist-packages/juju/control/__init__.py", line 183, in main
    env_config.load_or_write_sample()
  File "/usr/lib/python2.7/dist-packages/juju/environment/config.py", line 229, in load_or_write_sample
    self.load()
  File "/usr/lib/python2.7/dist-packages/juju/environment/config.py", line 115, in load
    self.parse(file.read(), path)
  File "/usr/lib/python2.7/dist-packages/juju/environment/config.py", line 138, in parse
    config = SCHEMA.coerce(config, [])
  File "/usr/lib/python2.7/dist-packages/juju/lib/schema.py", line 266, in coerce
    new_dict[k] = self.schema[k].coerce(v, path)
  File "/usr/lib/python2.7/dist-packages/juju/lib/schema.py", line 233, in coerce
    new_subvalue = self.value_schema.coerce(subvalue, value_path)
  File "/usr/lib/python2.7/dist-packages/juju/lib/schema.py", line 301, in coerce
    return self.schemas[selected].coerce(value, path)
KeyError: 'mass'

environments:
maas:
type:  mass
mass-server:  http://192.168.0.30:80/MAAS
mass-oauth:  tDRdtJeEKVARBh93eT:N5dK5HSZBsA45cBdx9:S8wMNrfkT9PeYvQN9YrnbHGxmKARv8vb
admin-secret:  ##########
default-series:  precise

Answer: type:  mass

Looks like you have some typos there, it should be maas at least.

juju bootstrap key error?


Why is Rupa (not) Ultimate Reality?

Question: When we see "a car' then there is the "seeing of the car formation" and that is mind or "nama". At the same time there is the rupa car formation that is not a concept from our mind. I always thought rupa was "the experience or hardness , softness, roughness ect.. but I guess this is wrong because rupa is it's own ultimate reality?
Answer: According to the Abhidhamma, we don't "see a car". It is a bit more complicated :-)
According to the Abhidhamma, sensing involves seeing a small patch of colour. The small patch of colour is rūpa, an ultimate reality.
How small is this patch of colour? Extend your arm and hold out your thumb. Scientists say that the size of your thumbnail as compared to your entire field of vision is what that retina can process at one instant. The rods and cones of the retina respond to specific colours.
Once this small patch of colour (the ultimate reality) has been seen, it becomes a concept (the tadanuvattikā manodvāravīthi process). Sensing is finished and now thinking takes over. The first thing that thinking does is the "grasp the object as a whole" (samudāyagāhikā); in other words, thinking builds up the entire field of vision from these "thumbnail-sized" patches of colour.
How is this done? It is not in the linear mechanical way that a TV screen image is built up. Scientists say that the eye focuses first on areas of high contrast, on faces and on movement before filling in the rest of the scene.
Once the entire scene has been built up, the thinking mind recognizes colours (vaṇṇasallakkhaṇā). Next, a shape or "entity" is extracted from the pattern of colours (vatthugāhikā). Next is the thinking process of recognizing the share or "entity" (vatthusallakkhaṇā). Next is a thinking process of gasping the name (car in the example you gave) (nāmagāhikā) and the thinking process of recognizing the name (nāmasallakkhaṇā).
Scientists explain that the activity in the brain extends from the visual cortex to involve memory.
Of course, next comes the idea of the car, judgements and associations regarding the car, obsessions and fantasies about the car.
What we see is the ultimate reality of a small patch of colour. Once seeing of this small patch of colour is complete, then thinking of concepts takes over.
This is explained in Bhikkhu Bodhi's "Comprehensive Manual of Abhidhamma" (page 164).
Answer: In traditional Hindu use of the words Rupa and Nama (in context of ontology), Rupa meant a configuration of matter and Nama meant a spirit or an identity embodied in that configuration. For example this particular combination of wooden planks is a Rupa, while the chair it embodies is a Nama. Even if some parts of the chair can get broken and replaced making it a different Rupa, it still remains the same Nama. Similarly, as the person gets older, the previous Rupa is nowhere to be found, but the Nama remains the same.
From this you can see that Rupa is not the Ultimate Reality, far from it. Rupa is just a transient configuration. This was well-known even before the Buddha.
What Buddha brought in, is clear understanding that Nama is a projection of the mind, that Nama is a conditioned phenomena too and is therefore impermanent.
As was famously said (SN 5.10):

So do you believe there's "a being"?
  -- this is a view of Mara.
  In a pile of mere components (sankhara)
   no any such being found.
  Just as they say 'chariot'
  of an assemblage of parts,
  So they'll call "a being"
  the mere heaps of components (skandha).

Here the pile of components is the Rupa, and the being / the chariot is the Nama.
So Rupa cannot be the Ultimate Reality, because it is compound and transient. Now, your next question could be, "but what about matter? can't matter be considered the Ultimate Reality?" - and the traditional answer to that is, the atoms are still made from pieces and those pieces are too made from pieces, so no matter how small we go things are always compound and transient. That is to say, as you go all the way down there is nothing like solid matter, there is only Rupa, transient configuration.
Answer: I think it is not correct to say "seeing of the car formation". When "you" see "a car" that is nama-rupa; it is just seeing - no doer nor object. The concept of "Car" is just mind-made.  Yes rupa is the experience of hardness, softness etc. But when you see a car, can you "see" the hardness, softness etc? So rupa is not the ultimate reality.
Answer: Here's my guess — however it's an unreferenced statement in Wikipedia.
Reality in Buddhist sutras

We can look at the concepts of impermanence and not-self in objective terms, for example by deconstructing the concept of an aggregated object such as a lotus and seeing that the flower is made up entirely of non-flower elements like soil, nutrients, photosynthetic energy, rain water and the effort of the entities that nourished and grew the flower. All of these factors, according to the Diamond Sutra, co-exist with each other to manifest what we call a 'flower'. In other words, there is no essence arisen from nothingness that is unique and personal to any being. In particular, there is neither a human soul that lives on beyond the death of the physical body nor one that is extinguished at death since, strictly speaking, there is nothing to extinguish. The relative reality (i.e., the illusory perceived reality) comes from our belief that we are separate from the rest of the things in the universe and, at times, at odds with the processes of nature and other beings. The ultimate or absolute reality, in some schools of Buddhist thought, shows that we are inter-connected with all things. The concept of non-discrimination expands on this by saying that, while a chair is different from a flower, they 'inter-are' because they are each made of non-flower and non-chair elements. Ultimately those elements are the same, so the distinction between chair and flower is one of quantity not of quality.

So:

The quote starts with "deconstructing the concept" (to see Rupa instead of seeing Nama).

Secondly it mentions "relative reality" which I think refers to Nama again, e.g. "that thing is named 'chair' and that other thing is named 'table': by comparing and naming them we see them as relatively different.
(see also "the Tao that can be named is not the eternal Tao" etc.).

Lastly it says that "ultimate reality" (which is what the OP asks about) is that we are interconnected, and I think its reason for saying that is that everything is created from the same stuff (i.e. Rupa) -- maybe that's saying that Rupa is more ultimately real (at the risk of introducing an anachronistic modern-science word, maybe Rupa is more "elemental").

From the context of the Wikipedia quote it might be a Mahayana doctrine (e.g. the quote mentions the Diamond sutra).
Answer: To continue this discussion further we must have an agreement of the (Dhamm) terms "Nama", "Rupa" and "Nama-Rupa" that we are using in this Question and answers.
There are three things to consider.
1). The Basic materials (Rupa Dhatu)/(particles).
2). The material creation / Form/physical phenomena- (a car)(Nama-Rupa).
3). The Perception/ Mental Formations.- (Nama Dhamma)
There are two usages according the difference of the understanding about the "car".
1). There is a car. (Aththi) - considering the structure as a thing.
2). There is no car. (Naththi) - considering the parts, No whole-( a thing).
But there is a "Mid point" (Kaccanagotta Sutta).

"'All exists': Kaccana, this is one extreme. 'All does not exist':
  this is the second extreme. Without veering towards either of these
  extremes, the Tathagata teaches the Dhamma by the middle:

3). When there is a person to perceive, then only "the car" exist.
(There is no sound in the forest-This is very special-Unique- finding in Buddhism).
We should use "Nama-Rupa" for this car. Because it is mental formation (sankhara).
It is Mind-made. ("Manopubbaṅgamā dhammā,manoseṭṭhā manomayā;").Dhammapada

Mind precedes all mental states. Mind is their chief; they are all
  mind-wrought.

Is there three things?
1). Can we sence/ identify (Rupa)Dhatu? - (Particals) -    No.  -  (Allways we sence whole lot).
2). Can we identify/ Sence separate (Nama) Dhatu? -    No.  -  (Allways we sence whole( single) feeling/Thought).
3). Can we sence/identify Consepts (Nama-Rupa)? -     Yes.  -  (It is mental creation).
 (In Any scale we sence only "Nama-Rupa"). So we cannot divide this to three. Only Nama-Rupa process(Vinnana) is the reality.
In Majjhesutta - 'Nama' is one end, 'Rupa' is the second end, Vinnana is middle,..

"nāmaṃ kho, āvuso, eko anto, rūpaṃ dutiyo anto, viññāṇaṃ majjhe,

Then what is Rupa?(Rupa Dhatu)?
We may assume we feel hardness, softness, roughness ext.  ...But they are all mental creations.
We can Know only the nature / Behavior of Rupa, Or its own ultimate reality - The Impermanency (Anithya) . (By using our own developed "Dhamma Chakku"-(Using Vipassana Mditation)/(Zazen)).
Then what is Nama?(Nama Dhamma)?
Our Thought process)/(Vinnana process) may identify (intention, attention, contact, feeling, discrimination) or (Vedana, Sanna, Chethana, Passa, manasikara) and any other mental factors(combination of Chathasikas).
But these are also mental creations. (There is no way -other than analyzing -to identify them. Except Using vipassana  to see the Anithya).
We cannot divide our experiences to"Nama" or "Rupa". Because every experience need Rupa for create form(Nama-Rupa) and Nama for identifying or feel them.  without "Nama" no experience and none can be happen without "Rupa".
So finally we can consider only "Nama-Rupa".
In English What is the word for this?
When somebody is watching something for so long they stop seeing details.
Comment: Are you agree on this?
Answer: From Ven. Bodhi's "Comprehensive Manual of Abhidhamma", ultimate reality(paramattha) can be seen as 4-fold: citta, cetasika, rupa, and Nibbana. These 4 are further classified into Sankhata(the conditioned) and ASankhata(the un-conditioned). Citta(mind/consciousness) and cetasika(mental factors) belong to the Nama(mentality) group, while Rupa is the materiality group. Both are under Sankhata. Only Nibbana is under ASankhata. A quick layout as below:
Paramattha(ultimate reality):
 |__1. Sankhata(the conditioned)
 |                 i. Nama(mentality): citta(mind/consciousness) and cetasika(mental factors)
 |                 ii. Rupa(materiality): forms
 |
 |__2. ASankhata(the un-conditioned)
                     Nibbana
Answer: The original question is about Brahmanism (namarupa-vyakarana) rather than about Buddhism.
The term 'nama-rupa' is confusing for many students of Buddhism because, in many suttas, the Buddha was speaking to Brahmans. Since those Brahmans did not understand the terminology of Buddhism, when the Buddha spoke to them, he was referring to nama-rupa as it was understood in Brahmanism.
(In addition, there are suttas obviously composed after the Buddha died probably for the purpose of preaching to & converting Brahmans, such as DN 15, since these suttas contradict the core principles of what the Buddha taught).
In Buddhism, a 'a car' is a sense-object of form (rūpāyatanaṃ) rather than 'rupa' (the physical body) as found in the term 'nama-rupa'.
The "seeing of the car formation" is eye contact (phassa) dependent on viññāṇa (consciousness) rather than "nama". "Nama' is defined as 'feeling, perception, intention, (internal) contact & attention (SN 12.2), and also other mental faculties, such as mindfulness (MN 111).
Therefore, that the car is a material thing (rupa dhatu) is an ultimate reality since, no matter how small the atoms of a car are broken down into smaller particles, those particles remain as rupa dhatu (material elements). Being rupa dhatu, the rupa dhatu contains no 'self' within it.
The essential matter about ultimate reality is the car is anatta (not-self) & sunnata (empty of self) since the car can never be held to permanently belong to any owner (due to its impermanence).
The car does not really have an 'owner'. This is the ultimate reality the Buddha was concerned with.

The eye is not yours: let go of it. Your letting go of it will be for your long-term happiness & benefit. Forms are not yours...
  Eye-consciousness is not yours... Eye-contact is not yours... Whatever
  arises in dependence on eye-contact, experienced either as pleasure,
  as pain, or as neither-pleasure-nor-pain, that too is not yours: let
  go of it. Your letting go of it will be for your long-term happiness &
  benefit.
SN 35.101

Why is Rupa (not) Ultimate Reality?


What makes a Feynman diagram real or virtual?

Question: Simple question: as the title says, what makes a real Feynman diagram real, and what makes a virtual diagram virtual? Or in other words, how do I tell whether any given diagram is real or virtual? I've never gotten a really satisfying explanation of this. I would imagine it has something to do with virtual particles, but all internal propagators are virtual particles and I know for a fact that having internal lines doesn't make a diagram virtual.
Comment: Hi David.  Must admit I've never heard of a "virtual Feynman diagram" before.  Do you have a reference for that?
Comment: http://arxiv.org/abs/1112.1061 in the abstract, http://arxiv.org/abs/1012.0507 above equation 4, http://arxiv.org/abs/hep-ph/9701284 in figure 1, and in the form "virtual contributions" (same meaning) http://arxiv.org/abs/1108.1752 above equation 10 and http://arxiv.org/abs/hep-ph/0109115 in the abstract. Also I think I've seen this usage in at least one textbook but I can't check it at this time.
Comment: I discerned from the papers the meaning of their terminology. See my updated answer.
Answer: In the normal usage, real and virtual are not properties of Feynman diagrams themselves, but of the particles depicted in them. The particles corresponding to external lines (attached to at most one vertex only) are real, the others (attached to two vertices) are virtual.
A Feynman diagram may be considered as a repetitive part of a bigger diagram. This requires that the external lines of the diagram are kept off-shell, so that the corresponding integrals depend on off-shell momenta (rather than only on-shell momenta, which would suffice for S-matrix elements). Their computation is more complex as one has to account for a bigger parameter space. The use of off-shell Feynman diagrams in this sense is that they can be used in resummation techniques as building blocks of infinite families of on-shell Feynman diagrams. Indeed, such a recursive usage necessitates treating the external lines as virtual.
As with virtual particles, such off-shell Feynman diagrams have no measurable counterpart but are just intermediate expressions in the resummation calculation.
However, in papers such as http://www.sciencedirect.com/science/article/pii/0550321379901160, a virtual Feynman graph is simply an ordinary Feynman graph involving a loop, in contrast to a real Feynman graph = lowest order tree graph. See the explanation after eqs. (42) and (81). This paper is quoted in http://arxiv.org/abs/1012.0507 after eq. (3) for details about virtual diagrams. In http://arxiv.org/abs/1112.1061, this terminology applies to the graphs cut at the lines in Fig. 1, corresponding to a factorization.
http://arxiv.org/abs/hep-ph/9701284 also uses this terminology; see the titles of Sections 3.1 and 3.2, and the corresponding figures.
Comment: It does seem like your last paragraph may be the answer I was looking for, but I really thought the distinction was something more than tree diagrams vs. loop diagrams. I'll see if I can figure out why I thought that.
Answer: If I understand your question correctly its just a matter of what you are calculating whether you put the external particles on shell or not. If you are, for example, calculating an amplitude to use for a cross section, you'll put the external particles on-shell and it will be what you call a 'real Feynman diagram'. If you are calculating an effective action you might draw the same exact diagrams as you do for a cross section calculation, but you leave the particles off-shell, or what you are referring to as a 'virtual Feynman diagram'.
Comment: I know that the diagrams I'm asking about have external lines on-shell, so this isn't the distinction I'm looking for. Though unfortunately I can't offer much else in the way of explanation, only a few examples of usage - if I knew what I was referring to, I wouldn't be asking the question ;-)
Comment: @DavidZaslavsky - I sort of figured you already knew that much, and I debated even posting it. Im still not clear though - is there a further distinction (i.e. subclasses of virtual vs real diagrams) you are asking about? Do you think something I wrote contradicts something in the links you provided?
Comment: Yes, I do. There are some in the links I provided where virtual diagrams have their external lines on-shell, which contradicts your statement that external lines of virtual diagrams are off-shell.
Answer: Feynman diagrams are just that: diagrams.
Real or virtual is what the particles depicted in them can be. A distinction should be made:
In order to calculate an amplitude, one needs to integrate over all possible momenta of internal lines. Therefore, those propagators can be thought as virtual. Effectively, one sums over all virtuality levels of the internal lines.
External lines are not as simple. While most are usually real, many are not. For instance, you can produce a pair of Z bosons from a total energy smaller than twice the Z boson mass. In that case one of the Z bosons will be virtual. If you measure it, you'll not find the Z boson mass, but something lower.
The same applies to the Drell-Yan process, where a virtual photon is created from quark-antiquark annihilation. These photons are massive, while real photons are massless.
Bottom line: diagrams are what they are. What comes out of them can be on-mass-shell (real particle) or off-mass-shell (virtual particle).


Definition of Fluctuations and Perturbations

Question: The terms fluctuations and perturbations are frequently used in physics with different meanings. But they are confusing. Both terms seems to be same. Is there any one who can explain lucidly these terms and show difference between these two terms?
Comment: In my experience, perturbation is most often used for something where perturbation theory (perturbation series) is applicable. http://en.wikipedia.org/wiki/Perturbation_theory
Answer: A perturbation is a small change (usually deterministic and known), while a fluctuation is a (not necessarily small) random perturbation with mean zero (and therefore either unknown or unrepeatable).
Usually one talks about a perturbation in the context of perturbation theory.
Perturbation theory is used to study a system that is slightly different from a nice system where you can do calculations easily; the difference from the nice system is the perturbation.
On the other hand, one talks about fluctuations when deriving results for the mean of certain quantities; the fluctuations are the deviations from the mean.
Another common word for fluctuations is noise (used in the singular only).
In realizations of stochastic processes, fluctuations are visible as contributions of large but irregular frequency, whereas a perturbation would be in this context a small change of a parameter of the system or the forcing term.
Answer: I would not pretend to be definitive on this, but I would take Fluctuations most often to refer to stochastic deformations of a $\mathit{particular}$ signal, whereas Perturbations most often refer to deformations (which can be either deterministic or stochastic) of a $\mathit{general}$ dynamics (which describes the time evolution of many different signals of a given type).
These words are appropriated in different ways by different authors, however, so that ultimately the sense intended has to be deduced from the mathematical constructions used.
I will be interested to see other people's take on the difference.
Comment: OK answer. One could also discuss oscillations and corrections in the same thread. There are various differences. Oscillations are small numbers (a bit bigger than fluctuations) around the "normal level" which are time-dependent. The time dependence sort of applies to fluctuations, too: fluctuations should be time-dependent. On the other hand, perturbations are changes made to the laws of physics, "before" we "kickstart" time evolution. Corrections are like perturbations except that perturbations should be corrections to a solvable/understood zeroth approximation, not a generic one. And so on.
Comment: Lobus MotI Answer makes sense but I am still confused anout these terms perturbations and fluctuation
Answer: Fluctuation
Suppose you repeatedly measure pressure $P$ in a piston due to gas in equilibrium. If your measurement apparatus is of high quality, you will read off numbers that fluctuate around a mean value $P_0$. Pressure, which is force divided by area, $P=F/A$, is due to gas molecules hitting the piston, and as the number of collisions and velocities vary, you'll have tiny fluctuations in your measurement.

Perturbation
Back in school we usually used the word perturbation to refer to perturbation theory (PT). PT is a way to model the dynamics of a physical system in a first, linear approximation. What we'd usually do is imagine that the system is in a stable equilibrium, i.e. it's sitting at the bottom of an energy valley. Suppose that the relevant parameter describing the system is $x$, its value for the energy minimum is $x_0$, and $E(x_0)=E_0$. You "perturb" the system, which means you imagine that the system moved away - for whatever reason - a little bit from the energy minimum; let $\Delta x = x_0 - x$. You can construct a perturbation series of energy in powers of $\Delta x$, like this: $E = E_0 + E_1 \Delta x + E_2 \Delta x^2 + ...$. Since we are perturbing around an energy mimimum, $E_1$ would be zero and $E_2 > 0$. You disregard higher order terms ($\Delta x^3$ and higher) because $\Delta x$ is small, and you end up with something like a spring, because $E \approx \Delta x^2$ in this approximation. This is linear, because the force law in this approximation is linear, as $F = - \frac{dE}{dx} = - 2 E_1 \Delta x$. What you end up with, in this first approximation, is oscillation around $x_0$.
An example that comes to mind is the oscillation of small test bodies like a satellite around stable Lagrange points of the Sun-Earth system (quotes from the linked Wikipedia page):
"When a body at these points is perturbed, it moves away from the point, but the factor opposite of that which is increased or decreased by the perturbation (either gravity or angular momentum-induced speed) will also increase or decrease, bending the object's path into a stable, kidney-bean-shaped orbit around the point..."
and
"The L4, and L5 positions are stable as a ball at the bottom of a bowl would be stable: small perturbations will move it out of place, but it will drift back toward the center of the bowl."


How do high-reputation SF users manages both SF and their office?

Question: According to answer on meta.stackoverflow, getting a high rep, you probably spend way too much time on the site and not getting your work done. How do they manage both?
Comment: I am waiting for windows to install.  It should finish in 39 minutes.   BTW sometimes when I am here I am actually trying to get work done by searching for answers to my questions.
Answer: Much of my rep is due to nothing more than time. Quite simply, given enough time even very ordinary answers can and do get rep as new people come across them. Decent answers benefit even more from time.
As for the time spent on the site, in my last job I was a one man IT department. By automating everything I could I ended up with some spare time during the day. Most of that time was spent learning new things and SF is one of the tools I use to learn. I don't answer many questions but I do read those that appear on the front page. In an average day I might visit SF 10 or more times but generally for only a few minutes at a time. Tea/coffee breaks and lunch time I also browse the questions.
Having been made redundant from that job, which was a direct consequence of said automation, I now work for myself and frequently visit SF for the express purpose of taking a break from what I'm working on, especially if I'm stuck on something.
Answer: And sometimes, an answer that you consider trivial will gain unexpected widespread attention and approval.
(Conversely, answers that you think could cause mankind to spontaneously rejoice and accept peace go almost completely ignored...)
But mostly it's just hanging out a little bit here and there.
Answer:
Comment: The best reason I know of for letting them have that second machine to compile on. ;)
Answer: Actually, I use ServerFault as a resource for work.
When I started the new job about half a year ago, I created my ServerFault account expressly because of the benefits it would provide me.  I've lurked and dropped in occasionally for specific problems since very soon after the site went public, but there are benefits to my employer above and beyond a solution to a specific problem to my participation here.
So it's not so much that I spend too much time on the site to get my work done, but that my activities on this site are part of "doing my job."  All the more so when you consider that most of my time on here (during working hours) is while I'm waiting on progress bars, or mulling over a decision that's part of the job.  Sure, it's a balancing act, and it's easy to fall into the trap of avoid work via Server Fault, but at worst, my activities on here make me a better sysadmin, which is more than can be said of browsing the web, reading news, doing fantasy football and the other similar activities most of the IT folk I work with do while they're waiting on progress bars.
So I guess I don't agree with the sentiment that a high rep here (or on SO, or even SU) translates to wasted/unproductive time, and the way I manage to both get my job done and participate on ServerFault is by treating the two activities as the intertwined/overlapping activities they are.
Comment: +1 I reckon that pretty much sums it up for most of us.
Answer: There was a good... 7 month period there where I was rather bored at work. The ongoing budget crisis (now abating somewhat, but that's now one job ago) meant that our usual pace of new projects had come to a halt and we were pretty much doing nothing but fire-watch and deploying home-grown services.
Firewatch, as we all know, is the act of waiting patiently for something to go wrong so we can fix it. Plenty of time to do other things, such as update documentation, blog, build scripts to improve automation, and answer all the questions on ServerFault. Firewatch was very good to my rep here.
Now I have a new job, and am significantly less bored. Also, I'm a moderator now which detracts from my answering-time. And yet in the not-quite-2 years I've had the diamond I racked up over 20,000 points. How? Over breakfast (like now), evenings, weekends, and the occasional break at work when I should be doing something I don't want to do.
By now I'd gotten into the habit of answering questions. I knew what a good answer looks like, know what kind of research needs to go into them, and importantly, how to write a good-looking answer. I even asked a few questions! This experience made the few answers I was able to get in end up earning quite a bit.
It doesn't take a lot to get to high rep quickly. Earning 100 points a day, half the rep cap, gives you 700 points in a week. This is enough to get you into the top 5 earners for a week. 100 points can be 15 answers, or it can be just the right 2. Keep that up for a few months and you'll be over 10K fairly quickly.
Answer: I'm not a high rep user on SF (yet!) but I am on SU. And the answer, quite simply is, you don't need to answer all that many questions to be a high rep user. On SU, I went for one good answer a day, maybe 2. On superuser I have 1571 answers for 39,111 rep in a total of 1063 days on the site (for comparison, I have 1934 rep on serverfault  for  79 answers over 718 days). At some point of time I hope to be able to answer more questions here, but its still a factor of skillset over time.
I have a few tricks - I love RSS feeds for sites I'm new to - its a good way to get a quick overview of active questions including the content of them. Many also recommend specialising in specific sorts of question.
You don't need to spend lots of time to get rep. You just need to work smart.
As for employment prospects - I think this answer is a pretty good alternate view. Its a matter of how you sell it - reputation means little, but community involvement and varied quality answers may show an enlightened employer you have skills the same way a reference would.
Finally, a smart sysadmin keeps his employer happy, and works as little as possible. I will leave the implications of that as an exercise to the reader ;).
Comment: +1 I only average 1.8 Answers per day; minimal effort over the long haul makes a big difference.


What are differences between "damage" and "injury"?

Question:
He claimed serious injury to his reputation.

Can I use damage?

The closure of the factory will cause severe damage to the local economy.

The ship sustained only minor damage.

Can I use injury, instead of damage? Are they synonyms?
Answer: If you tell someone about serious injury, the first thing comes is the physical harm to someone.
OALD defines this word and it is mostly used for physical harm

injury - harm done to a person's or an animal's body, for example in an accident

However, injury can happen to someone's feeling (on the same page).

injury - Damages may be awarded for emotional injury.

In usage note injury OALD defines being injured where instances are of physically being hurt.
Being a medical professional, I'd like to mention that damage can also happen to human organs (especially internal) but then it could be the result of an injury or harm by bad microorganisms

In that road accident, he got several injuries. In fact, his liver is damaged and needs to be repaired. OR  I have never seen such worse septicemia. Her internal organs are damaged and will stop working soon.

But again, if you are talking about someone's reputation or injury in the context of non-living thing, use damage to keep ambiguity at bay.
Don't get confuse that damage can be used for physical harm. 'Physical' can be used for non living things like computers and books etc. :)
So, a ship is a non-living thing so it might sustain damage and let the closer cause damage to the economy, not injury. :)
Comment: You omitted one important note about the context of *injury* being used for "damage to a person's feelings". Your dictionary says "(law)".
Comment: It isn't related to the OP Question, but "such worse" does not sound like natural English.
Comment: @TecBrat not sure what do you mean by *natural* English!  *"...have been terrifically disturbed **due to such worse** weather condition.* - from the US Trade Media
Answer:
Injury: a wound or damage to part of your body caused by an accident or attack.

For example: "She was taken to hospital with serious head injuries."
So because the word injury is used for animate person, we cannot use damage instead of it.

Damage: physical harm that is done to something or to a part of someone's body, so that it is broken or injured.

For example: "These chemicals have been found to cause  serious environmental damage."
So we cannot use injury instead of damage in that sentence.
Comment: Do you notice that each definition includes the other word?
Answer: In the case of He claims serious injury to his reputation;
Here, the reputation of a certain person is personified.(why?)
Lets get thorough with the definitions first:
An injury affects a living organism, the likes of you and me
Damage affects a non-living object, like a car
So they can not be used interchangeably.
Lets get back to your word usage:

He claimed serious damage to his reputation

Is absolutely correct.

The closure of the factory will cause severe injury to the economy.

Is incorrect and should be replaced with damage.

The ship sustained only minor damage is correct. Injury here is incorrect.
Comment: _In general_, **injury** would be damage to a living thing, while **damage** would be injury to a non-living thing. :) There _are_ special cases, such as the legal term _injury to your reputation_. However, you can seldom go wrong restricting _injury_ to living things (including plants) and _damage_ to anything else, both tangible and intangible objects.


Does the progressively more aerodynamic design of starships suggest that more were fitted with landing gear?

Question: We see in the gradual evolution of Federation starship design from the Constitution Class to the Intrepid Class a much more aerodynamic design in starships.  We know that the Intrepid class has landing gear and that warp drive does NOT mandate an aerodynamic shape (ie Borg Cube), so is it reasonable to assume that Federation starships by the time of VOY were being fitted out with landing gear, hence the aerodynamic designs (like that of the Sovereign class)?
Comment: The Borg prefer their trans-warp conduits, so they may not be the best example of this.
Comment: Ships also got faster over this period, and the events of *Force of Nature* imply a concern with fuel efficiency (sorta-kinda) parallel to the oil crisis of the 1970s,inspiring a need for more efficient designs.  Also, the Borg are the ONLY race without streamlining in their ships, so it probably reflects a quirk in their technology rather than that aerodynamics are irrelevant to warp travel.
Comment: I would guess that the more streamlined shapes were to reduce damage done to subspace by the warp drives ([Force of Nature](http://en.memory-alpha.org/wiki/Force_of_Nature_%28episode%29)).
Comment: @MajorStackings - I am not asking for people's opinions, but whether this is true or not or whether this is actually a reasonable assumption- a canon matter and *not* opinion.
Comment: Having a tough time not vtc. This question screams    "What's your opinion?"
Comment: There is also the question of aesthetics. Given the flatter design of the Enterprise NX-01, the fact that Voyager looked more "streamlined" may actually, to people of the time, make it look more "retro" than Galaxy-class designs.  The wide range of starship designs from different races seem to imply that shape isn't a terribly important decision, practically.  Therefore, it could just be a matter of evolving design style, or trying to impart a sensibility, like Nazi aircraft being designed to look predatory and intimidating.  Just speculation, though, so I'm not adding it as an answer.
Comment: @N.Soong I made the comment because of the way the question is worded. IMO, it seems to be asking for a verification of an   assumption that may or may not confirm a suggestion.
Answer: Related Question: In Star Trek, would space particles impart drag on the ship, even if moved by the deflector field?
While this question appears to be opinion based, there are some things easy to spot if you pay close attention and think a bit about it. So it's not pure speculation.
Let's have a look at one specific scene during Voyager's opening credits:

As you can see, the gas clouds seems to react to the deflector field and/or shields (by lighting up), but at the same time that happens pretty close to the actual hull.
So even if you assume that no "space particle" ever touches the hull, a streamlined design might still be advantageous simply due to the fact that this makes it easier to project a field around the ship that is streamlined as well.
If you've got the technology, you can most likely adjust the field to ignore your ship's shape and/or simply overcome these issues as a whole (Borg cubes).
If you want a real world experiment or analogy: Think about how you could use garden sprinklers to create a "force field" of wetness. If you place them around the shape of your "ship", the resulting field will have a similar shape. If you don't want that, you'll have to increase pressure (i.e. more force/power/energy), which isn't necessarily that ideal if you can just (re-)shape your ship to compensate for that.
Now one might argue that in most combat scenes, shields appear as spherical bubbles around ships. This is true, but IMO this is just due to two things:

It's far easier (cheaper and faster!) to render; especially considering that rendering tech was very expensive (and slow) in the 90's.
It's a common misconception regarding "starship design". A sphere is a perfect shape and what you'll get from one single emitter (if it isn't directed/shielded in some way). But as all Star Trek series suggest, there's never just a single shield emitter. Most ships should feature at least four emitters (otherwise it wouldn't be possible to have shields collapse at one point of the hull only for example).
Answer: The Star Trek: The Next Generation Technical Manual, which was written by Rick Sternbach and Michael Okuda who were visual designers for the show as well as the main "technical consultants" (on some combination of real science and the reasonably consistent fictional science of the show), suggests that shape of the Enterprise-D was determined largely by warp physics, as well as the new requirement that the saucer be able to separate and from the "Battle Section" and coast at warp for some time (see Tango's answer to this question for more on this idea of the saucer "coasting" despite lacking its own warp engines). From p. 5:

Seen from a comfortable distance of two or three kilometers, the
  starship takes on the graceful lines of a nonrepresentational organic
  sculpture. Nature has determined the flow of the design, adhering
  closely to mathematical formulae at work in the universe surrounding
  the builders. Even in the desire to expand beyond the apparent limits
  of the natural world, familiar forces create familiar shapes. As the
  rapid aquatic and avian creatures of dozens of habitable worlds
  independently developed the unmistakable attributes of streamlining,
  so too did their interstellar cousin.
The combination of forces produced within the warp engine core and the
  flow of space and subspace around the vessel created the particular
  engineering solution to the problem of faster-than-light travel. The
  initial Starfleet requirement that a single spacecraft be able to
  perform as three distinct vehicles presented some rather
  complex—though some engineers not normally afraid of numbers preferred
  the word "daunting"—computational challenges.
The docked configuration presented the most efficient use of warp
  flight forces, but the Battle Station was also required to perform the
  specifications at warp velocities on its own, and the Saucer Module
  would have to have the capability of high sublight speed and possibly
  survive a separation at high warp. Scientists and engineers throughout
  the Federation, with all the deportment of composers and conductors,
  arranged sweeping curves, described vast volumes, and summoned up
  fantastic energies to bring their creation into existence.

Also on p. 66 they write:

Third, the shape of the starship hull facilitates slippage into warp
  and imparts a geometric correction vector. The Saucer Module, which
  retains its characteristic shape from the original concept of an
  emergency landing craft, helps shape the forward field component
  through the use of a 55º elliptical hull planform, found to produce
  superior peak transitional efficiency. The aft hull undercut allows
  for varying degrees of field flow attachment, effectively preventing
  pinwheeling, owing to the placement of the nacelles off the vehicle
  Y-axis center of mass.

Also, in the book U.S.S. Enterprise: Owner's Workshop Manual, written by Ben Robinson and Marcus Riley with Michael Okuda as a technical consultant, there's a sidebar on p. 97 titled "Warp Development Theory":

The warp "bubble" in which a starship rides at faster-than-light
  speeds is not a static structure. Rather, it is a flowing, pulsing,
  ever-shifting field of energy that dictates the shape of a particular
  starship. Even minor changes in starship design must undergo extensive
  testing and optimization to ensure safety and propulsive efficiency.
Field geometry is particularly sensitive to variations in the position
  of the warp engine nacelles. While in conventional (slower-than-light)
  spacecraft design, the propulsive thrust vector must travel through
  the vehicle's center of mass, warp propulsion is quite different. Warp
  drive requires the nacelle axes to be offset from the vehicle's
  centerline to create the propulsive imbalance. This technique usually
  requires the forward field lobe (normally containing the saucer
  section) also to be offset from the nacelle vector. In many older
  ships the nacelles were located slightly above the forward lobe. The
  NX and Constitution-class starships used this design, which yielded superior field stability, although it also resulted in reduced
  propulsive efficiency.
During the 2260s, the Advanced Starship Design Bureau began to
  experiment with field geometries that lowered the nacelle vector with
  respect to the forward field lobe. This approach promised improved
  engine performance but required several years of research into new
  field-stability software. Among the first vehicles to employ the new
  approach was the experimental Starship Excelsior, whose design
  lowered the nacelle centerline so it was level with the saucer module.
  This design was reflected in the Excelsior-class Enterprise-B.
  Further advances in field control software allowed even more radical
  designs for the Ambassador-class Enterprise-C, and the
  Galaxy-class Enterprise-D, both of which saw the nacelles move even lower than the frontal lobe.
Strangely enough, recent advances in deflector field technology have
  resulted in a reversal of this trend in nacelle position in some of
  the latest ships. New ultra high frequency shield generators have
  allowed the Sovereign-class Enterprise-E to employ higher nacelle
  positions, while enjoying an additional 3 per cent in engine
  performance.
The arcane engineering of warp field geometry continues to be a
  subject of intense study at Starfleet's Advanced Starship Design
  Bureau and will undoubtedly continue to be an area of ever-changing
  research and innovation.
Answer: I think the word streamlining would be a better fit then aerodynamics. Even Voyager used raw power over principles of lift when in atmosphere. 1701 D's saucer section was only designed to land as a last ditch effort and not as routine. Moving through space though, does present problems similar to atmospheric flight. Space is littered with micro meteorites and other debris. A minimal frontal exposer, helps to reduce the risk of collision damage. Most designs also include a form of navigational deflector array just to prevent damage. For protection in situation such as combat, another system of shielding would be used. In a real situation surrounding a ship in a bubble like energy construct would be impractical. To get a bubble only using one emitter, it would have to be at the ships center of gravity. that would mean projecting all that energy through the crew. Doesn't sound healthy. Placing multiple emitters on the hull and balancing them in a bubble shape, would waste energy. So shielding fields would extend from the ship in a pattern closer to that seen in infra red photography, or electromagnetic scans of an MRI.
Answer: What "looks" aerodynamic and what "is" are not the same.
Underwater test of models in Japan prove this.
1701, 1701 (refit), 1701a, glide through the water with little effort or control.
The Enterprise 1701-D still stable but requires effort to keep stable
USS Voyager requires massive modifications (clear plexi ) stablizers just to move in a straight line.
The farther away from the round saucer design, the less stable and aerodynamic the hull becomes.
BTW
Other stable designs are
Disney's Nauteliss, the Starblazer's Yamato, Seaview from Voyage to the bottom of the Sea.
Comment: Welcome to SciFi.SE! I'm afraid I don't think those tests are really relevant: a comparatively tiny plastic model moving through *water* does not indicate how well the full-size vessel will travel through *air* at substantially higher speeds.


Why are the wings of some modern gliders tadpole shaped?

Question: Why are the wings of some modern gliders tadpole shaped, rather than teardrop shaped? An example is the Schleicher ASG 29. Or did they just add a flat plate at the trailing edge for the flaps and ailerons?

Source: flickr.com
Answer: The flaps and ailerons are "reflexed" on this glider. They have been raised to a setting above the normal zero position, above the airfoil's normal chord line. A number of flapped gliders have this feature.
Two main benefits are a reduction in pitching moment as the pressure distribution on the wing is moved forward, so less downforce work for the tail, reducing trim drag, and lower induced drag because with the trailing edge partially unloaded it has an effect like reducing wing area and moves the best L/D speed up a bit.  So overall, best glide angle is a bit better, and the speed it's achieved is a bit higher.
You use reflex for "penetration", going as flat as possible as fast as possible, for whatever reason, like getting through an area of sink in a hurry.
Comment: I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D.  Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up.  You only see it on simple plain flaps.
Comment: do airliners use this "reflexing" technique?  It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
Answer: Flapped airfoils will have a suction peak once the flap is deflected away from its zero deflection position. This means more load on the boundary layer and earlier flow separation at the same lift coefficient. In order to avoid this suction peak over a range of flap angles, the airfoil contour is optimized on the top side for a small positive deflection and on the lower side for a small negative deflection. Now you get that "tadpole" shape between those two flap deflections, but also more flap effectivity and lower drag.
This effect is increased on the upper side for negative flap deflections. They are standard on gliders in order to shift the laminar bucket of the airfoil to the actual lift coefficient. I bet the lower side contour of the wing in the photo is smooth across the flap hinge line.
Answer: You can position the flaps/ailerons on the ASG 29 not only downwards but also upwards. The flap/aileron is triangle shaped as you can (barely) see on this photo of an ASG 29 wing joint:

Basically you can reduce the lift (and therefore drag) of the wing by moving the flaps/ailerons upwards, extracting better speed from the wing.
Answer: The upward flexure of the trailing edge of the airfoil does two things:

It maintains attachment of the flow boundary layer across the airfoil surface and decreases drag.  Separation of the boundary layer would increase pressure drag and, essentially, momentum of the separated flow that is now being carried by the aircraft.  This would decrease penetration and adversely affect airspeed and lift-drag ratio.

For a sailplane within its maximum flight performance envelope, it decreases the forward pitching moment of the wing.  Nose-down pitching would increase airspeed and sink-rate, thereby requiring up-trim of the tail-plane to counter the nose-down tendency.  This up-trim also increases drag, thereby adversely affecting the lift-drag ratio. Up-trim can also be maintained by shifting the center of gravity aft by moving trim ballast aft. Nevertheless, the best flight characteristics for maximum lift-drag ratio of a high-performance sailplane are maintained through neutral trim settings producing no essential drag (an aerodynamically balanced aircraft), and a clean wing flying within its best performance range at the given altitude and airspeed (that is, wing Reynolds number and angle of attack).
Answer: Effectively the raised flap lowers the angle of attack by virtue of the variation of the chord line.
Less drag, higher speeds for, as has been said, penetration.
Comment: This answer could be significantly improved by adding a picture or diagram.


Is Michigan the only US state without a State of Emergency (or similar type of order)?

Question: On October 2, 2020, the Michigan Supreme Court (MSC) released an opinion regarding the Governor's state of emergency renewals. The syllabus of the opinion states that:

The Governor did not have authority after April 30, 2020, to issue or renew any executive orders related to the COVID-19 pandemic under the EMA (Emergency Management Act of 1976).

and:

The Governor did not possess the authority to exercise emergency powers under the EPGA (Emergency Powers of the Governor Act of 1945) because the act unlawfully delegates legislative power to the executive branch in violation of the Michigan Constitution.

The Governor asked the MSC to allow for a transition period before ending the state of emergency. The MSC announced October 12, 2020 that its ruling was effective as of October 2, removing any doubt.
The Michigan Legislature at this point has not passed a bill restarting the state of emergency.
Is Michigan the only US state without a state of emergency (or similar type of order)?
Comment: Fortunately (or unfortunately) Michigan is still under lockdown via Health department orders. So effectively they're not any different.
Answer: According to this list on the National Governors Association website, Michigan is in fact the only State no longer under a state of emergency or similar order (although their list is not yet reflective of the Michigan Supreme Court Opinion).


What does the word "Star" in "Star Wars" refer to?

Question: I wonder what the word "Star" in Star Wars refers to. Why did George Lucas choose this title for his epic? The word "Wars" is clear, but I don't know what "Star" refers to. Does anyone know?
Comment: Space, I guess.
Comment: Planets also revolve around stars so Star Wars are about the wars taking place on and across a specific galaxy of planets and/or solar systems. I also think it was to convey the sense of adventure, inspiration, and wisdom, as we often say, 'look to or reach for the stars' It also points out the light and dark motif, which is at the center of Skywalker Saga's epic and views on the force.
Comment: It fits the graphic design better than Space Wars [leaves one letter hanging] or Universe Wars/Galaxy Wars... for similar reasons... & it's punchy, to the point, no room for argument, all-encompassing, obvious, open to any plot-line, timeless...
Comment: @Tetsujin, perhaps he'd prefer it was called Spaceballs...
Comment: Because it's easy on the tongue probably, or it would've been space wars or stars wars.
Comment: Why is the word "wars" clear to you? There are no wars in the films.
Comment: @Mouvier, it's a weird question, no wars in the films!?! Regardless of small fights between empire forces and the rebelliions. Death Star Assault (New Hope). Battle of Hoth (The Empire Strikes Back). Battle of Endor and final great war to destory Death Star and the empire (Returen of the Jedi). The Gungans fight with Droid Army (The Phantom Menace). Battle of Clones, Jedi with droids and the separatists (Attack of Clones). Battle Of Coruscant and fianl purging of the Jedi and opposition of the Empire by the clones.
Comment: Those are not wars but rebellion.
Answer: In case it's not clear, a star (in this context) is:

Any small luminous dot appearing in the cloudless portion of the night sky, especially with a fixed location relative to other such dots.
(astronomy) A luminous celestial body, made up of plasma (particularly hydrogen and helium) and having a spherical shape. Depending on context the sun may or may not be included.

Source: Wiktionary
The literal meaning of the title could be interpreted as "A series of wars among the stars". "Among the stars" is a turn of phrase used to mean "out in space".
Compare with the title Star Trek, which means "a journey (trek) among the stars".
Also compare with the TV show Star Search, which means "a search for stars". In this case, "stars" means people who will become famous, not large balls of hydrogen fusion in space, but the grammar of the title is the same.
In general, an English construction of noun verb often means, "doing verb in the context of noun". For example, sea trade is the trading of goods using ocean vessels. Shore leave means "a break from service that takes place on dry land (not at sea)". Space walk means "an excursion from a spacecraft wearing only a spacesuit or EVA suit" - in other words, "a walk in space".
If that doesn't clarify things enough, you might want to ask your question on the English Language & Usage Stack Exchange.
Comment: Star meaning leading character is not the intended meaning at all.  It refers to stellar, celestial objects.
Comment: The idea you told was the thing I guessed and it could be right. "Stars" may refer to important people who are heroes and villains in both good and evil sides. like the stars or superstars when we talk about famous celebrities.
Answer: While Todd Wilcox' answer is true in the literal sense that Star Wars refers to the wars happening across the galaxy on planets and in outer space, it also refers to both a metaphorical (prominent heroes and villains) and metaphysical (power coming from elsewhere) definition.

Star Wars is an American epic space-opera media franchise created by
George Lucas. The franchise began with the eponymous 1977 film and
quickly became a worldwide pop-culture phenomenon.

Star Wars, especially the Skywalker family Saga (Epsiodes I-IX) is about "iconic" Heroes and Villains who are featured in this particular story, as the story itself asks, what does "legacy" mean? What information can we pass on?

Epic films are a style of film-making with large scale, sweeping scope,
and spectacle. The usage of the term has shifted over time, sometimes
designating a film genre and at other times simply synonymous with
big-budget filmmaking. Like epics in the classical literary sense it
is often focused on a heroic character. An epic's ambitious nature
helps to set it apart from other types of film such as the period
piece or adventure film.

To expound on that, because the work is also a "Fantasy Epic", there is also a metaphysical energy, The Force, that is believed to connect all life together, but some are born "Force Sensitive" and can tap into this energy and kinetically use it.

Star Wars features elements such as knighthood, chivalry, and
archetypes related to the fantasy genre. The Star Wars galaxy,
unlike science fiction that features sleek and futuristic settings, is
portrayed as dirty and grimy in Lucas's concept of a "used
future". Lucas made a conscious effort to parallel scenes and
dialogue between films, and especially the journey of Anakin Skywalker
in the prequels with that of his son Luke. He has collectively
referred to the first six episodic films as "the tragedy of Darth
Vader," and said that the theme of the saga is redemption.[196]
The final scene in The Last Jedi depicts servant children playing with
a toy of Luke Skywalker, and one boy using the Force to grab a broom.
According to Inverse, this symbolizes that "the Force can be found in
people with humble beginnings."

In the first two trilogies of the Skywalker Saga the general tenor of 'good vs evil' comes from light side and dark side "force users" referred to as the Jedi and Sith. The first trilogy sees the rise and fall of Anakin Skywalker that is echoed in the downfall of the Republic and the Jedi Order, juxtaposing the rise of The Empire and birth of Darth Vader through the Sith Lord, Darth Sidious or Emperor Palpatine.
In the next trilogy the twin children of the Anakin Skywalker must attempt to restore order to the galaxy, as Anakin's son Luke learns the ways of the fallen Jedi in order to confront his father, whose now a destructive Sith Lord.

EMPIRE - Rian Johnson Interview
"He's taken himself out of the fight, he's sitting on that island in
exile. I know the Luke I grew up with is not a coward, he's not
sitting out there hiding, so I had to come up with a reason he was
there that was active and positive, and something I could genuinely
believe I could think in his shoes," says Johnson. "And the thing that
came to me that seemed to make sense to me is this notion that he
seems this hero worship of him and of the Jedi that is detrimental to
the galaxy. The universe has put its faith in its false god of the
Jedi and they need to forget the religion so they can get back to god,
that light can rise from a worthier source. And because he's the last
Jedi and a symbol of that, it then becomes this self-sacrifice he has
to do to take himself out of it when he knows his friends are dying,
when he knows the thing he'd like to do is get back in the fight. He's
taken the weight of the world on his shoulders by taking himself out
of the equation so that the Jedi can die out. The end of the movie is
him embracing the part of the past that the present needs, which right
now is the legend of Luke Skywalker, they need something to believe
in, they need that action figure of Luke Skywalker to grab on to, that
inspiration to stare up at the stars and believe that you can be a
hero."
"I wanted Luke's death to be peaceful, to be on his terms I wanted it
to be a victory. I wanted it to be that he's done this huge grand act
that has restored the spark of hope to the galaxy. I'm hesitant to put
into words what he does in the end, but it is completed."

In the last trilogy, the Republic was restored, but fell pray to the Empire turning into the New Order, where Darth Vader's grandson, who claims not to be Sith, eventually comes to power leaning into the dark side. But it is his Uncle, Luke Skywalker's legacy and his possible feelings for an outsider named Rey, that threatens the success of The New Order quashing the resistance once and for all, but Luke sacrifices himself and stories about his bravery and honor are spread across the galaxy inspiring a whole new generation of people to join nearly defeated resistance, aka the "Spark of Hope"! (We have to wait and see how the last episode plays out to know more.)
"May the Force be With You."
In addition, through out these works and in other works, including Star Wars Rebels, the notion of what The Force is and how one should use it (methodology/applied philosophy) is debated, but in many cases there is evidence that the Force does in fact exist and have a "will" and therefor there is an additional mysterious element of fate at work (some Force Users may be able to see the future), which gives Star Wars philosophical and/or spiritual meaning, as the Force is coming from within and beyond the self; a metaphorical definition playing on "stars" as in information coming from somewhere else, like from "God" or the "The Heavens"...
Comment: Not true, there are "rising stars" in Star Wars rebellions, resistance, Empire, etc "in-universe" meaning that it can refer to ANYONE who is famous or iconic, as their reality does not keep them from the construct of "political recognition", which any EPIC would heavily rely on. Luke's Skywalkers "legacy" (a well known person whose stories about them are spread to others) is what saves the resistance at the end of the Last Jedi. It's thematic to the whole 'Skywalker' legacy and is major a plot point.
Comment: @whiskeychief sure, Barack Obama, Martin Luther King Jr, Amelia Airheart, Rosa Parks, Bono, David Bowie, etc/ While it may be true culturally we don't often refer to athletes, musicians (Rock STARS), politicians, inventors, and rights activists as "stars" (meaning famous heros), the truth is some do and you can: https://www.theatlantic.com/politics/archive/2018/12/how-rising-political-stars-31-years-ago-fared/578398/
Comment: Also there is a Star Wars book titled, Lost Stars, which refers to a doomed romance between two leading characters who ended up on opposite sides (rebellion/empire) thus "stars" referring to the main characters while debating notion of being "star-crossed". It also refers to military locations and weapons such as "Star" Destroyers and the second Death "Star".
Comment: Come on.  "Star" does not mean hero, it means "actor in a Hollywood movie".   Can you name one real-life hero in our society that you'd refer to as a "star"?


ASP.NET Session State Server vs. InProc Session

Question: What is the overhead performance penalty for running Session State Server instead of InProc? Is it significant? I understand that you can restart w3wp with the state server and retain all session state - is that the only advantage over InProc?
Answer: It depends on your deployment plans: on a single server, the penalty is small, but the benefit is equally limited: your session state survives process recycles (as mentioned) but that's about it. You'll have some cross process marshalling with StateServer mode, so expect some additional cpu load, nothing too impressive.
In a web farm/load balanced setup InProc won't work, unless you can configure sticky sessions/server affinity. Be mindful of the fact that the StateServer node itself can become a single point of failure, so be sure to compensate for that. Having said that, the latency of a StateServer is in general much less (= better) than when you use SQLServer mode.
Make sure that your code/site gracefully handles lost state, regardless of where you store the data.
Answer: If you have a load balance setup (without the use of sticky sessions) you cannot use InProc since (based on your load balance setup of course) you might switch between nodes.
Recycles of the worker process (but that is of course the same as restarting w3wp) will also kill your session when it is InProc.


No music contents on iPhone after synchronization

Question: Every time I synchronize my iPhone with iTunes on my computer, for example, when I want to add new music to my iPhone, I suddenly lose all my music on the iPhone.
I recently wanted to add a new album to my iPhone. So I plugged it in via USB, checked the album for synchronization in iTunes and started synchronization. After a while it finished and said "Synchronization done. You can disconnect your iPhone now blah blah…".
But when I looked at my iPhone and opened the iPod app, it says: "No contents". How is this possible? In iTunes there is an overview telling you how much space is full and what the space is used for. There I see 4,5 GB for Apps, 7 GB for music and some space for other stuff. On my iPhone I can check the space too, and there it also says that there should be the 7 GB of music, but the iPod app doesn't show any contents.
I also tried to restore my iPhone multiple times with different back-ups. It works until I sychnronize my iPhone the next time. Another strange thing is that restoring my iPhone isn't easy at all. It often aborts, showing random error messages (6,9,14). This is really annoying and I'm about to throw my iPhone against a wall.
Has anyone had similar problems and found a solution?
iPhone:

iPhone 4 (32 GB)
iOS 4.3.5
no jailbreak

PC:

iTunes 10.4.0.80
Windows 7 64
Comment: Too bad that there is so few activity on apple.stackexchange...
Answer: I think this might be your problem: Windows 7 64
If you can, try to sync your phone from a 32 bit machine. Since the dawn of the iPhone Apple hasn't played nicely with 64 bit flavors of Windows. This fellow says there's a HotFix from MSFT to fix the issue.