Creating a stackoverflow-like website
Are there any clones/alternatives for running a Stack Exchange style Q&A site?
Is there such a thing as a switch that can be actuated automatically? I'm interested in a toggle switch that can be toggled without user input. That is, the physical state can be toggled electrically. It would need to incorporate some sort of motor or magnetic actuator. My google-fu is weak in this area, and I haven't been able to come up with the correct combination of search terms.  Note that I'm not talking about a relay; I'm talking about a normal toggle switch:    Except that it can be toggled without user input. As in, the lever physically moves. Like a  except that the mechanism is internal to the switch. White cloudy areas on bottom of new stainless steel skillet I just bought my first few pot and pans "Calaphon" stainless steel trip-ply  I used my new 10" skillet tonight, and cooked pork chops. I heated the pan first, added olive oil, let it heat, then added chops. After I was done, cleaned it immediately under water, and noticed white cloud looking areas on the bottom of the skillet. They won’t wash or rub off  Do I need to return these? I did buy them for the look as well. My floating point number has extra digits when I print it How can I control the name of generic WCF return types? I've got a WCF Web Service method whose prototype is:  [OperationContract] Response&lt;List&lt;Customer&gt;&gt; GetCustomers();   When I add the service reference to a client, Visual Studio (2005) creates a type called "ResponseOfArrayOfCustomerrleXg3IC" that is a wrapper for "Response&lt;List&lt;Customer>>".  Is there any way I can control the wrapper name?  ResponseOfArrayOfCustomerrleXg3IC doesn't sound very appealing... "Reality" of length contraction in SR I was in argument with someone who claims that length contraction is not &quot;real&quot; but only &quot;apparent&quot;, that the measurement of a solid rod in its rest reference frame is the &quot;real length&quot; of the rod and all other measurements are somehow just &quot;artificial&quot; and &quot;apparent&quot;. Seemed to me like a bad conversation about poorly defined words and not really relevant to physics, but then some quotes were offered:  ...so that the back appears closer to the front. But of course nothing has happened to the rod itself.  (Rindler)  The effects are apparent (that is, caused by the motion) in the same sense that proper quantities have not changed.  (Resnick &amp; Halliday) At the same time, the  insists that length contraction and time dilation are &quot;real&quot;, with observable consequences:  Time and space dilation are often referred to as ‘perspective effects’ in discussions of STR. Objects and processes are said to ‘look’ shorter or longer when viewed in one inertial frame rather than in another. It is common to regard this effect as a purely ‘conventional’ feature, which merely reflects a conventional choice of reference frame. But this is rather misleading, because time and space dilation are very real physical effects, and they lead to completely different types of physical predictions than classical physics. [...] However, this does not mean that time and space dilation are not real effects. They are displayed in other situations where there is no ambiguity. One example is the twins' paradox, where proper time slows down in an absolute way for a moving twin. And there are equally real physical effects resulting from space dilation. It is just that these effects cannot be used to determine an absolute frame of rest.  I went through a lot of Einstein, Minkowski and Lorentz original material, and didn't find anything about what is &quot;real&quot; and what is not. Finally, I know about muons, where the effects of SR seem to be very real (from , but I had seen it in a physics class before):  When a cosmic ray proton impacts atomic nuclei in the upper atmosphere, pions are created. These decay within a relatively short distance (meters) into muons (their preferred decay product), and muon neutrinos. The muons from these high energy cosmic rays generally continue in about the same direction as the original proton, at a velocity near the speed of light. Although their lifetime without relativistic effects would allow a half-survival distance of only about 456 m (2,197 µs×ln(2) × 0,9997×c) at most (as seen from Earth) the time dilation effect of special relativity (from the viewpoint of the Earth) allows cosmic ray secondary muons to survive the flight to the Earth's surface, since in the Earth frame, the muons have a longer half life due to their velocity. From the viewpoint (inertial frame) of the muon, on the other hand, it is the length contraction effect of special relativity which allows this penetration, since in the muon frame, its lifetime is unaffected, but the length contraction causes distances through the atmosphere and Earth to be far shorter than these distances in the Earth rest-frame. Both effects are equally valid ways of explaining the fast muon's unusual survival over distances.  So which is which? Why do Rindler, Resnick &amp; Halliday use the word &quot;apparent&quot;? Let $E$ be a finite dimensional vector space over field $\mathbb R$ with $E^*$ as the dual space of $E$.($\dim E=n$)   $\Omega^P(E):=\{ \alpha\colon \overbrace{E\times\cdots\times E}^{p- times}\rightarrow \mathbb R\  \ , \alpha \text{ is alternating multilinear map}\}$ $\Omega^P(E^*):=\{ u\colon \overbrace{E^*\times\cdots\times E^*}^{p- times}\rightarrow \mathbb R\  \ , u \text{ is alternating multilinear map}\}$  I wish to prove that there exist an $\textbf{unique}$ bilinear form $B\colon \Omega^p(E^*)\times\Omega^p(E)\rightarrow\mathbb R$   such that for all $ f_i\in E^* \ , u_j\in E^{**}\simeq E \qquad  i,j=1,\cdots,p$, it has the following rule:  $B(u_1\wedge\cdots\wedge u_p,f_1\wedge\cdots\wedge f_p)=\det[f_i(u_j)]$.  $\wedge$ is wedge product between alternating maps i.e. $\alpha\wedge\beta(v_1,\cdots,v_{p+p})=\dfrac{1}{p! p!}\displaystyle\sum_{\sigma\in S_{p+p}}sign(\sigma)\alpha(v_{\sigma(1)},\cdots,v_{\sigma(p)})\beta(v_{\sigma(p+1)},\cdots,v_{\sigma(p+p)})$  How can I do this? How can I repair grub? (How to get Ubuntu back after installing Windows?) I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back? Pivot in SQL 2008 R2 Right-Click menu awareness on Web Application The web application I am building has a custom right-click menu. I'm concerned that the user might not find this menu as normally right-clicking will only display the default browser's menu. Is there a standard way to make the user aware of custom right-click menus? Is there another way to show this information? Do gravitons interact with each other? I always thought the non-linearity of Einsteins field equations implies that there should be direct graviton-graviton interactions. But I stumbled upon  which argues:     If gravitons exist, then, like photons and unlike gluons, gravitons do   not interact with other particles of their kind. That is, gravitons   carry the force of gravitation but are not affected by it. This is   apparent due to gravity being the only thing which escapes from black   holes, in addition to having an infinite range and traveling in   straight lines, similarly to electromagnetism.   Is Wikipedia correct? If not, why not? And what then are the arguments that there must be graviton-graviton interactions?    (As of this question being asked, the above paragraph has been removed from Wikipedia.) No reason for anyone to see pending close votes, except OP (and maybe people who already voted) What happens to Bucky's arm at the end of Infinity War? Bucky (Winter Soldier) has a metal arm (possibly made from vibranium?) but it's an attachment to his body as far as I understand. Why, when Thanos destroys half of the universe at the end of Infinity War, does his metallic arm also disappear with him? Shouldn't it be left behind as his gun did? I am running Ubuntu 15.10 with Gnome DE.  I installed KDE plasma to try it out but sudo apt-get upgrade started giving me errors so I ppa-purged the kde ppa and removed kubuntu desktop with the terminal in Gnome.  Now when I run sudo apt-get upgrade , I get the following error:    The following packages have unmet dependencies:     kde-telepathy-minimal : Depends: kde-config-telepathy-accounts      (&gt;= 15.04.0) but it is not installed.   sudo apt-get install -f does not resolve the issue. I tried sudo apt-get remove kde-telepathy-minimal to remove the package which gives me this error:    The following packages have unmet dependencies: kde-telepathy : Depends: kde-telepathy-minimal   Attempting to remove 'kde-telepathy' gives me the original error.  I am stuck. Please help me and thank you Ubuntu community! I have an internet connection that I'd like to be enabled only during the day. With multiple household internet devices, this would need to be something disabled at the level of the router.  I don't believe the router offers this sort of functionality, but I'm reasonably familiar with setting up web servers and the like, and I'm wondering if I can set up some sort of proxy server on the internet that the router must go through and have that proxy only active at certain times of day.  It's a bit vague I know, but is something like this even possible?  If not, are there other solutions to the problem? How to make a bootable ISO image from a bootable DVD? I want to make a .iso image of a bootable OS DVD, to use in VirutalBox.    Nautilus can make a .iso, but only of data files, it seems. The .iso it created was not bootable.  What is available to make a bootable .iso from a bootable DVD? How should tiny $p$-values be reported? (and why does R put a minimum on 2.22e-16?) For some tests in R, there is a lower limit on the  calculations of $2.22 \cdot 10^{-16}$. I'm not sure why it's this number, if there is a good reason for it or if it's just arbitrary. A lot of other stats packages just go to 0.0001, so this is a much higher level of precision. But I haven't seen too many papers reporting $p &lt; 2.22\cdot 10^{-16}$ or $p = 2.22\cdot 10^{-16}$.   Is it a common/best practice to report this computed value or is it more typical to report something else (like p &lt; 0.000000000000001)? Say my opponent plays a planeswalker during their first main phase.  I have a  or some other effect that will kill it after it is already in play, but before they use any of its abilities.  I could respond to them using a +1 ability, but I want to kill it before that effect goes on the stack.  In most casual situations, it would basically come down to whether I say "Hero's Downfall" first, or they say "+1" first.  But I can't imagine that's how it's supposed to work.  Is there a time between when the planeswalker hits the battlefield and when they activate its abilities that they must let me respond? It seems to me that situations like this arise frequently, and they are resolved simply by who speaks up first, which is horrible for such a rules-oriented game. My Windows folder takes up too much space - how can I reduce it? In typical PCs the Size of Windows Folder is 6 to 8 GB but in my Case its 25GB. How can I delete the unwanted files from the Windows Folder (which, in turn, will optimize my C Drive size).  My system is Windows 7 with 60 GB in C Drive with 59 GB occupied. What's the -alhF flag in ls? What is the -alhF flag in ls? I can't find it in the . Trouble downloading packages list due to a "Hash sum mismatch" error