Is there variation in the speed of light?
GR. Einstein's 1911 Paper: On the Influence of Gravitation on the Propagation of Light
What are your favorite English language tools? To prevent myself from asking an obvious, silly question multiple times: What are the English language tools you found most useful?  I found  extremely useful for looking up .   Please, one tool per answer. IOS 5.1.1 Safemode problem I jailbroke my old iPod Touch 3rd Generation, with IOS 5.1.1, using the latest version of absynthe. It worked for several months, but then it randomly stopped. It went into safe mode, but the touch screen wouldn't work. It showed the lockscreen, but nothing worked at all, except for the physical buttons. The only way to reboot is to follow the same steps as DFU mode (Hold power button 3 sec, then home button AND power for 10, then just home for 8)... However, it always boots right back into Safe mode.  I had to restore, and once rejailbroken, it worked fine, until I installed SBsettings. Then it did the EXACT same thing, and I had to restore and re-jailbreak AGAIN! The other day, I finished installing ALL of my extensive list of tweaks, and got it to about where I wanted it, when lo and behold, it booted to safe mode again. I have spent so much time on this, and I do not want to do it again. Does anybody here have any knowledge on the topic? Is there a program I can run from my computer to manually control the device or kick it out of safe mode? Is there some other method of doing this? I am looking for any solution OTHER than restoring. I have done that several times.  Also, I know the problem isn't with my jailbreak. It worked for several months before, then one day stopped. Now, it has the problem within a day of rejailbreaking, OR instantly if I install SBsettings. I re-installed the jailbreak, and applied the new one as well, and that didn't work. I have given up, and don't want to go through the painful process of restoring, rejailbreaking, and re-installing all of those tweaks again.  Also, because I can't get into my iPod, I can't provide a list of tweaks. I would if I could, but it just can't happen unless I can get in there. Free UML drawing library for .NET Convert NSDate to NSString How do I convert, NSDate to NSString so that only the year in @"yyyy" format is output to the string? Where can I find good literature for beginners? I am trying to find some database tutorials,books and similar, since I have started this course in college, and received some material, but it is really hard to manage through all the info on the net. I searched through the questions on the site but didn't find any. Thankfull for all your input. Identify duplicate lines in a file without deleting them? I have my references as a text file with a long list of entries and each has two (or more) fields.   The first column is the reference's url; the second column is the title which may vary a bit depending on how the entry was made. Same for third field which may or may not be present.  I want to identify but not remove entries that have the first field (reference url) identical. I know about sort -k1,1 -u but that will automatically (non-interactively) remove all but the first hit. Is there a way to just let me know so I can choose which to retain?  In the extract below of three lines that have the same first field (http://unix.stackexchange.com/questions/49569/), I would like to keep line 2 because it has additional tags (sort, CLI) and delete lines #1 and #3:  http://unix.stackexchange.com/questions/49569/  unique-lines-based-on-the-first-field http://unix.stackexchange.com/questions/49569/  Unique lines based on the first field   sort, CLI http://unix.stackexchange.com/questions/49569/  Unique lines based on the first field   Is there a program to help identify such "duplicates"? Then, I can manually clean up by personally deleting lines #1 and #3? Line breaks in listings Is there a way like wrap the line after at most 60 letters but it should not break inside some commands like listings does?  Example:      \documentclass[a5paper]{article}     \usepackage[T1]{fontenc}     \usepackage[utf8]{inputenc}     \usepackage{listings}     \usepackage{xcolor}      \lstset{%       language=[LaTeX]TeX,       backgroundcolor=\color{gray!25},       basicstyle=\ttfamily,       breaklines=true,       columns=fullflexible     }      \begin{document}     \begin{lstlisting}     The roadrunner is the fastest running bird \remark{Check this again with a zoologist!}.     \end{lstlisting}     \end{document}   Output:      The roadrunner is the fastest running bird         remark{Check this again with a zoologist!}.   That should not happen! In my eyes this problem is not discussed in . better Curve/Text to Mesh generation? The triangulation process of Text to Mesh or Curve to Mesh generates some nasty topology.   I get why, but maybe it could be done a bit nicer? Since text is flat, have ngons instead of hundreds of triangles you'll need to modify anyway?  Another issue is when you then want to use the text as a Volume for particles, which for some reason behave weird when you have unusual topology even though they should be using the volume, not vertex or face positions. Methods to compute $\sum_{k=1}^nk^p$ without Faulhaber's formula What language is the Ubuntu Software Center written in? Just been wondering, since elementary AppCenter is written with Vala and Gtk+3.  Also, what GUI wrapper does it use? I've got a project where I'm looking to tweak the standard lead conversion process.   Triggers and lead conversion has always been funky in past projects so I was hoping to start the design off by reviewing the order of execution, but after a long google search I'm coming up empty handed.   Anyone out there know the specific trigger order for lead conversion?    Edit: I'm not asking about trigger execution order for any object, but all the objects created in the lead conversion process.  I'd think it would be something like this:        Lead Before Update Triggers (isConverted = false, convertedAccountId = null, convertContactId = null, convertedOpportunityId = null)         Account Before Insert Triggers (not fired if merged with existing account)   Account After Insert Triggers (not fired if merged with existing account)   Contact Before Insert Triggers (not fired if merged with existing contact)   Contact After Insert Triggers (not fired if merged with existing contact)   Opportunity Before Insert Triggers (not fired if no opportunity) (OpportunityContactRoles null)   Opportunity After Insert Triggers (not fired if no opportunity) (OpportunityContactRoles = convertedContactId)   Lead After Update Triggers (isConverted = true, convertedAccountId = XXX, convertedContactId = XXX, convertedOpportunityId = XXX) What is the command to open the shutdown dialog? What are the “spam” and “rude or abusive” (offensive) flags, and how do they work? Do I have a virus on my phone? A message from an Android app says so I have just received a message from an Android app on my phone saying my phone has been infected with a virus and to click a link to fix the problem.   I'm not sure I trust this, is it possible to have a virus on Android? I know you can select a tag and then click on unanswered to view the unanswered questions for that tag.  But is there a way to view questions only for a certain set of tags > 1 tag?  Mainly I'd like the union of tag1 with tag2 with tag3 with tag4. But also the intersection of tags would be nice as well. I accidentally rsynced .thunderbird to user@host instead of to user@host:/home/user.  Where is .thunderbird now?  Is there a good way to search for the folder? How do I size a UITextView to its content? What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(text) {     if (window.clipboardData) { // Internet Explorer         window.clipboardData.setData(&quot;Text&quot;, text);     } else {         unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege(&quot;UniversalXPConnect&quot;);         const clipboardHelper = Components.classes[&quot;@mozilla.org/widget/clipboardhelper;1&quot;].getService(Components.interfaces.nsIClipboardHelper);         clipboardHelper.copyString(text);     } }  But in Internet Explorer it gives a syntax error. In Firefox, it says unsafeWindow is not defined. A nice trick without using : I'm hand-maintaining an HTML document, and I'm looking for a way to automatically insert a link around text in a table. Let me illustrate:  &lt;table&gt;&lt;tr&gt;&lt;td class="case"&gt;123456&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;   I would like to automatically make every text in a TD with class "case" a link to that case in our bug tracking system (which, incidentally, is FogBugz).  So I'd like that "123456" to be changed to a link of this form:  &lt;a href="http://bugs.example.com/fogbugz/default.php?123456"&gt;123456&lt;/a&gt;   Is that possible? I've played with the :before and :after pseudo-elements, but there doesn't seem to be a way to repeat the case number. I normally dual-boot with 12.04 and Win XP pro sp3 on a Thinkpad R60.  I needed to reinstall windows because of problems piling up, so I ran the computer's built-in hard-disk recovery software.  I told it not to mess with the other partitions, but somehow it deleted the Linux partition.  That's what I was using to backup all of my windows files, so now everything I have is gone.  I just ran the USB setup with linux, and the partition is deleted - it just shows it as empty space.    Is there ANY way to get all of my files back?