Phrase for saying something is impossible at all? I am looking for good way of translating my native language way of saying something is impossible and will never be possible, i.e., Kan lungtat a par hunah le which literally means 'When our grindstone comes into blossom'. The grindstone which is used for sharpening knife can never sprout and grow tall and come into bloom. For example, So when someone asks for the impossible, we respond 'When our grindstone blooms' for emphasizing the impossibility. Is there an equivalent phrase in English?
What is the equivalent of Persian idiom "When the reed blooms"? In Persian, we say "When the  blooms" when we want to  express that an event:   Never happens. (This is only the opinion of the speaker so it's not a fact) It's very unlikely to happen. It's going to take so long to actually happen. (It's so long that you'd be better off giving up expecting it)  3.1. We also use it when someone is always postponing something they have to do so you never actually see it happen.   For example:      Kyle: When are you going to pay my money back?      Cartman: When the  blooms.   Now I don't know if I got the plant's name right because there are some other versions like:        In any event, they have mentioned this plant in the idiom because apparently some versions of it actually never bloom. Others believe it's because farmers harvest them before they get the chance to bloom (e.g to make music instruments), so it never happens. I'd love to know the equivalent idioms or expressions for this.  PS: I only know "When pigs fly" but I'm not a fan of it because the word pig sounds a bit rude to me and partly because it implies a strong impossibility which doesn't work for the #3 use.
Is there any relation between the chromatic number of a graph $G$ and its complement $G'$ that are always true?  I saw these ones: $\chi(G)\chi(G')\geq n$ and $\chi(G)+\chi(G')\geq 2n$,  but I'm not pretty sure about them. How do I kill background processes / jobs when my shell script exits? I am looking for a way to clean up the mess when my top-level script exits.  Especially if I want to use set -e, I wish the background process would die when the script exits. How to get Intel Dual Band Wireless-AC 3168 work on Ubuntu 16.04? How can I stand on the ground? EM or/and Pauli? I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps? In other words, how to prove:  For all real constants $a$ and $b$ such that $a &gt; 1$, $$\lim_{n\to\infty}\frac{n^b}{a^n} = 0$$  I know the definition of limit but I feel that it's not enough to prove this theorem. Add space before and after tabular environment The tabular environment does not add any vertical space before or after it. This looks odd, in my view. What is the "correct" or "best" way to add some space? Also, why is there more space after the tabular environment than before it, as seen in the example below?  \documentclass{article} \begin{document} \noindent Here is a line with some text in it.  \begin{tabular}{*4{l}}     Worg &amp; Worg &amp; Worg &amp; Worg\\     Worg &amp; Worg &amp; Worg &amp; Worg\\ \end{tabular}  \noindent Here is another line with some text in it. \end{document} Add-on for blocking sites in Google Search I want to block Yahoo Answers from Google searches. As there is no option from Google for that, are there any extensions for Chrome or add-ons for Firefox that can block sub-domain results from Google search? Why is the (free) neutron lifetime so long? A neutron outside the nucleus lives for about 15 minutes and decays mainly through weak decays (beta decay). Many other weakly decaying particles decay with lifetimes between $10^{-10}$ and $10^{-12}$ seconds, which is consistent with $\alpha_W \simeq 10^{-6}$.  Why does the neutron lives so much longer than the others? Can I delete unnecessary device simulators of Xcode? I found that Xcode on my laptop consumes much of its storage, so I am trying to delete unnecessary files in Xcode.  There are four directories under Application/Xcode.app/Contents/Developer/Platforms/. I feel that WatchSimulator.platform and AppleTVSimulator.platform are not necessary, because I use Xcode almost only for basic iOS development.  I would like to know if I can delete those platforms directories directly? What is the difference when you say "get off of something" and "get off something"? Why don't applications update by calculating difference? What does --shell-escape do? I stumbled upon an example, which needed to be compiled with the additional option --shell-escape. Using this option it worked just fine, but I'm curious:     Why or when is this option needed and what does it actually do? I have being using Skype for a long time on my Ubuntu 14.04 LTS. From this morning on, Skype simple cannot connect to my account anymore.  That is my Skype version:     Skype 4.3.0.37   © 2014 Skype and/or Microsoft   My Ubuntu system:  LSB Version:    core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch:core-4.1-amd64:core-4.1-noarch:cxx-3.0-amd64:cxx-3.0-noarch:cxx-3.1-amd64:cxx-3.1-noarch:cxx-3.2-amd64:cxx-3.2-noarch:cxx-4.0-amd64:cxx-4.0-noarch:cxx-4.1-amd64:cxx-4.1-noarch:desktop-3.1-amd64:desktop-3.1-noarch:desktop-3.2-amd64:desktop-3.2-noarch:desktop-4.0-amd64:desktop-4.0-noarch:desktop-4.1-amd64:desktop-4.1-noarch:graphics-2.0-amd64:graphics-2.0-noarch:graphics-3.0-amd64:graphics-3.0-noarch:graphics-3.1-amd64:graphics-3.1-noarch:graphics-3.2-amd64:graphics-3.2-noarch:graphics-4.0-amd64:graphics-4.0-noarch:graphics-4.1-amd64:graphics-4.1-noarch:languages-3.2-amd64:languages-3.2-noarch:languages-4.0-amd64:languages-4.0-noarch:languages-4.1-amd64:languages-4.1-noarch:multimedia-3.2-amd64:multimedia-3.2-noarch:multimedia-4.0-amd64:multimedia-4.0-noarch:multimedia-4.1-amd64:multimedia-4.1-noarch:printing-3.2-amd64:printing-3.2-noarch:printing-4.0-amd64:printing-4.0-noarch:printing-4.1-amd64:printing-4.1-noarch:qt4-3.1-amd64:qt4-3.1-noarch:security-4.0-amd64:security-4.0-noarch:security-4.1-amd64:security-4.1-noarch Distributor ID: Ubuntu Description:    Ubuntu 14.04.3 LTS Release:    14.04 Codename:   trusty   Any suggestion why or how to fix it?  Thanks in advance. Torus object stretched in array curve modifier I have a chain object. And i have a curve it follows. I got it to work for following curve, but chain object is not circles but both parts are more like stretched circles (ovals). Object i made with 2 toruses one rotated 90 degrees and then joined them together. I tried single torus too. But same issue. on a curve it just looks stretched oval. What can be the issue?   Thanks I want to use  to display my CPU-Core temperatures (haswell i7). However the setting:  order += "cpu_temperature 1" #... cpu_temperature 1{         format = "T: %degree °C" } #   doesn't display the correct core temperature. The numbers it shows seem to correspond to the value xsensors shows for temp1, if I change the 1 to 2 above it corresponds to xsensors temp2. Trying 3 or 4 doesn't have any effect. However I want to get the true core temperatures of all 4 cores with i3 status. How can I do this? The well-known fable of an astronaut sending signals out to an external observer while falling toward an event horizon states that the time lapse between such signals becomes greater even if in the astronaut sends them out periodically (as judged in his inertial frame). When viewed from earth and weighing time-dilation due to the gravitational field of the collapsing star, how is it possible that a black hole can form in finite time (for any external observer) if it takes an infinite amount of time to "see" events occurring at the event horizon? Why do some people use $+\infty$ instead of $\infty$? Why do some people use $+\infty$ instead of $\infty$? Because we usually denote minus infinity as $-\infty$, I think it is sufficient to denote plus infinity as $\infty$. Are there any reasons for this notation? I saw that many people majoring analysis use like $\int_0^{+\infty}$ or $\sum_{j=1}^{+\infty}$ or $\bigcup_{j=1}^{+\infty}$ which is not related to the unsigned infinity. How do I set a default host for nginx? I'm trying to figure out how to set a default host for my nginx installation. I found this article in the nginx Wiki:    Unfortunately, this doesn’t work. After restarting I get this:  Restarting nginx: nginx: [emerg] unknown directive "http" in /etc/nginx/sites-enabled/catchall:1 nginx: configuration file /etc/nginx/nginx.conf test failed   After removing the http directive I get this:  Restarting nginx: nginx: [emerg] unknown log format "main" in /etc/nginx/sites-enabled/catchall:7 nginx: configuration file /etc/nginx/nginx.conf test failed   I’m on Ubuntu 10.04.3 where I’m using the official nginx PPA. Version 1.0.9 of nginx is running. Do file descriptors optimise writing to files?