In the movie A New Hope we see Obi-Wan training Luke to use the lightsaber of his father.     HAN: Hokey religions and ancient weapons are no match for a good blaster at your side, kid.   Blasters are as good as guns and their velocities surely help in tearing off enemies. With the help of force they are surely good weapons.  Can’t Jedi interact with the force with help of blasters?  Please consider using spoiler tags in your answer as I have only watched Episode IV
Why do Jedi use lightsabers instead of blasters? Blasters seem to be more practical. Is there a special bond or something between lightsabers and Jedi?
Norms Induced by Inner Products and the Parallelogram Law Let $ V $ be a normed vector space (over $\mathbb{R}$, say, for simplicity) with norm $ \lVert\cdot\rVert$.  It's not hard to show that if $\lVert \cdot \rVert = \sqrt{\langle \cdot, \cdot \rangle}$ for some (real) inner product $\langle \cdot, \cdot \rangle$, then the parallelogram equality $$ 2\lVert u\rVert^2 + 2\lVert v\rVert^2 = \lVert u + v\rVert^2 + \lVert u - v\rVert^2 $$ holds for all pairs $u, v \in V$.  I'm having difficulty with the converse.  Assuming the parallelogram identity, I'm able to convince myself that the inner product should be $$ \langle u, v \rangle = \frac{\lVert u\rVert^2 + \lVert v\rVert^2 - \lVert u - v\rVert^2}{2} = \frac{\lVert u + v\rVert^2 - \lVert u\rVert^2 - \lVert v\rVert^2}{2} = \frac{\lVert u + v\rVert^2 - \lVert u - v\rVert^2}{4} $$  I cannot seem to get that $\langle \lambda u,v \rangle = \lambda \langle u,v \rangle$ for $\lambda \in \mathbb{R}$.  How would one go about proving this? How would gravity change on a planet rotating around itself very fast? Let's take a planet identical to Earth, but with rotation speed multiplied by ten thousand. What would happen with the gravity if it was spinning madly around itself? Would the centrifugal force make objects seem lighter than on normal Earth? Would the people on that planet be able to jump higher? Is it just for me, or has the privilege to review new posts and late answers changed for everyone?  I recently started being more active in reviewing, but the rep requirement just shot up and I can not review anymore? The rep requirement has shot up to 500. Is this just for me, as a 'process", or has it been changed site wide? Calling a function of a module by using its name (a string) What is the best way to go about calling a function given a string with the function's name in a Python program.  For example, let's say that I have a module foo, and I have a string whose content is "bar". What is the best way to call foo.bar()?  I need to get the return value of the function, which is why I don't just use eval. I figured out how to do it by using eval to define a temp function that returns the result of that function call, but I'm hoping that there is a more elegant way to do this. Why do my lamps require an insane "strength" value of 1 million? What is the connection between special and general relativity? What is the connection between  and ? As I understand general relativity does not need the assumption on speed of light constant. It is about the relation between mass and spacetime and gravity. Can general relativity be valid without special relativity? I've seen a lot of people talking about FPGA's before and I know that it stands for field-programmable gate array but how does it work and what is the purpose of using an FPGA? How can I show that $ab \sim \gcd (a,b) {\operatorname{lcm} (a,b)}$ for any $a,b \in R \setminus \{0\}$? Let $R$ be a UFD. Then for any two elements $a,b \in R \setminus \{0\}$ $ab \sim \gcd (a,b){\operatorname{lcm} (a,b)}$.   My attempt :  Let $d = \gcd (a,b)$.Then $d|a$ and $d|b$.Then $\exists x,y \in R$ such that $a = dx$ and $b = dy$.Now it is to be shown that $c = dxy$ is the lcm of $a,b$.Which I find difficulty to show.It is clear that $a|c$ and $b|c$. Now if $u$ is any common multiple of $a$ and $b$.Then $dx|u$ and also since $y|b$ we have $y|u$ i.e. $dxy|u^2$ $\implies c|u^2$.But I have to show $c|u$ to complete the proof which I fail to prove.Please help me to complete the proof.  Thank you in advance. Note: TL;DR, scroll to bottom for summary. I recently set up my computer for a dual boot between Ubuntu 9.10 and Windows 7. My current drive setup is as follows.  | A1 |     A2       | | B1    |  B2  | B3 |        A1: 100 mb, windows 7 "System   Reserved" boot partition      A2: 230 gb, data section, this one   needs to be shared between the   operating systems      B1: 125 gb, windows 7 OS      B2: 123 gb, ubuntu OS      B3: 2gb, linux swap space     Pretty much I want to have my documents, music, pictures, videos, etc accessible from both operating systems. My first attempt involved making the data (a2) partition NTFS, and moving my home folder from ubuntu to the data partition. However, as I read NTFS does not work nice with permission, and it messed up my home folder. My next idea is one of the following: 1) format the data partition to ext2/3/4 and move my home folder from linux there, and get a driver to read ext partitions in windows 7. The problem with that is that most of the ext drivers/software are not compatible with windows 7 or do not integrate with windows explorer (I really don't want to open a separate software window just to access my data, plus it's probably not compatible with other software.)  looks promising, but I'm not sure how it works with ext4 and windows 7 (not officially supported, when trying in Vista Compatibility Mode, it tells me I need to format the ext drive to use it). My next idea, 2) keep the home folder in ubuntu where it is, but create symlinks for the Documents, Music, etc folders to an NTFS formatted Data (A2) partition, and add those locations to the windows 7 libraries. I'm not totally sure how the permissions would work out, but it should be fine since it's only the documents, music, etc and not the important config files in the rest of /home/user/. Correct me if I'm wrong. Currently, symlinks is my best idea, although i'm not sure how it will work.  Any suggestions, additions to my ideas, links, pointers, whatever would be greatly appreciated. Even if it means I should reformat both my drives and repartition (2 250gb drives if you want to suggest a setup for that), I won't be too opposed if that's the best suggestion (I've gone through the format/install/format/reinstall process 5 times over the past 3 days, once more won't hurt me).    TL;DR, summary:  I have two hard drives. One is partitioned for Ubuntu and Windows 7, the second one I want accessible to both operating systems to store documents, music, pictures, videos, etc. Suggestions on how to set up the data drive.    P.S. bonus if I can get an apache server document root folder working between the two OS's as well (permissions could become very complicated, so don't worry too much about that)  P.P.S. Related question, but data viewing is one way: Can anyone explain precisely what IOWait is? How to stop Katoolin from crashing Ubuntu? Is "I am sat" bad English? I believe it is incorrect and instead either the present continuous     I am sitting   or the predicate adjective     I am seated   should be used.  I hear this quite often, however, and ultimately usage overrules formality.  Does anybody know where this originated or how to describe it grammatically? Affiliate Ads Are Coming To The Network Some time ago, we announced that . This has gone well and we're extremely thankful to everyone for their support and feedback. Because it has been successful so far, we're going to be extending the program to the majority of our graduated sites. Well, we've pretty much already done that, but there are quite a few sites that have ads enabled, yet still display nothing. The thing is, we don't really have an abundance of clients offering products that a  would find relevant, but Amazon has stand mixers, a selection of super fine chinois, deliciously sharp cutlery and enough cast iron to fill the Gulf Of Mexico with . Beginning as early as this week (week of 5 February 2018), our ad team is going to be hand selecting affiliate ads to be displayed on select sites. The use of inventory will of course depend on the availability of relevant ads to display which means:  Some sites might see very few, if any ads. Some topics simply don't come remotely close to orbiting anything worth advertising. Furthermore, while graduated, some sites simply don't have enough activity for ads to make sense.  Since these are hand-selected, it could take a while for ads to appear initially.  These would of course yield to inventory from clients if clients had products that were relevant to any given topic.   Nothing changes when it comes to the . If you're used to occasionally seeing a community promotion ad, you'll just notice that you'll also occasionally see an ad for something that is likely to be of interest to someone interested in the topic that your site covers. In fact, to be clear, this is simply a continuation of the announcement we made in November of 2016. We just wanted folks to know that we're going to be continuing the program where there's good potential to show relevant advertisements, even if we don't have clients lined up with a demand for it. Where can I give feedback about a certain ad on [site]? Open a meta post on your per-site meta and let us know. Please remember, the bulk of advertisements are an effort to get something small back from folks that hit the sites through search engines and are extremely unlikely to ever become contributors. Their soufflé stopped falling, and we'll probably never see them again. Maybe we can get a few bucks once they realized that copper ions help egg whites stiffen properly and buy a bowl or a proper bloom whisk. However, you're the experts on these topics and we're very likely going to listen to you. What sites, specifically? Are any sites exempt? If you're a former Stack Exchange 1.0 site and / or subsequently joined the network under a special charter, nothing changes - don't panic :) For the rest, we're just extending what we're currently doing with ads on graduated sites to also include those where there's an opportunity to make sensible use of affiliate ads. If a site has less than 15k (average) daily visits, or fewer than roughly 50k combined total posts - it might not yet be time to invest in selecting ads to be shown there. But, part of this exercise is also seeing what works best. I don't really have feedback, just some suggestions Ads aren't just an opportunity to sell stuff, they're an opportunity to really show people that we understand a given topic. That, of course, makes suggestions from people that do that stuff every day quite valuable. Post on your per-site meta and our community / ad critters will take a look. Questions? Comments? Kvetches? Let us know in an answer or comment below. If anything about the plan changes, we'll update this post to let folks know. We know that $e^{\pi i} = -1$ because of de Moivre's formula. ($e^{\pi i} = \cos \pi + i\sin \pi = -1).$  Suppose we square both sides and get $e^{2\pi i} = 1$(which you also get from de Moivre's formula), then shouldn't $2\pi i=0$? What am I missing here? Is there really any difference between the jackknife and leave one out cross validation? The procedure seems identical am I missing something? My new laptop came preinstalled with Windows 8. Naively, as I am, I just formatted the harddrive and installed fine old Ubuntu. Now I want to install Windows 8 for dual boot again, but I have no DVD and do download the ISO one needs a product key. That key is not on the back of the laptop anymore but somewhere on the mainboard.  Is there any way to recover the product key from the mainboard using Ubuntu? Short sci-fi story about Earth blockaded by other human colonies Like the subject: short sci-fi story about Earth blockaded by other human colonies.  The best humans have colonized some stellar systems. But they begin to treat humans of earth like inferiors. A war began, colonies won the war and blockaded the earth, but despite this the earth won. Who is the author? Cardinality of Irrational Numbers I know and I have proved more than once that the set of irrational numbers ($\mathbb{I}$) is uncountable, but now I'm given to solve this problem:   Show that $|\mathbb{I}|=|\mathbb{R}|$,  How can I do that?  Do I need to assume the Continuum Hypothesis in order to that statement to be true?  Thanks read.csv warning 'EOF within quoted string' prevents complete reading of file Is the below a valid circuit implementation and are there any things to watch out for? It's a simplification of the larger circuit but the crux of it is that I need to sink current into two GPIO input pins. The pins are signified by the 1 and 0.  Also, would a diode on the pins be advisable?    Edit: Here's the non-simplified circuit. The question relates to the 3.3v part of it. In essence, the timer and decade counter sequentially pulse current, 'activating' the transistors one at a time. The keypad is a simple matrix keypad. What I'm wondering if I can do is to put a GPIO pin on the line between the keypad and ground. The intended effect is that, when a button on the keypad is pressed, 2 pins will change state - this signifies the row and column.  Note that some of the resistance and capacitance values are notional at the moment.