Travelling at a relative speed greater than the speed of light
If I run along the aisle of a bus traveling at (almost) the speed of light, can I travel faster than the speed of light?
I've been thinking of animating some dice and while most are easy to make, I'm having some trouble figuring out a way to generate a regular dodecahedron. I could hand build it but it would be potentially uneven. Would using the base of a 5 sided cylinder and then some variation on spin be the best option or is there a better way? Does a gluon have mass or not? I was under the impression that gluons had no mass. Then Wikipedia throws this curveball:  Mass: 0 (theoretical value) &lt; 0.0002 eV/c2 (experimental limit)  Which one should a poor soul go by? If the theoretical value just the one that people &quot;thought&quot; was right, until they found out the truth, or is the experimental limit(?) an impossibility that still has not been explained? Or something third? Windows 7 won't boot after installing Ubuntu 11 How can my module add xml sitemap entries? Unfortunately MyApp has stopped. How can I solve this? Why is everything floating in space so cold? Of course there is pretty hot stuff too. For example Suns.  But isn't the vacuum of space the perfect containment for heat? And shouldn't the rare collision with particles even heat up an object that floats around in space?  Why aren't they hot from time to time? Is it because they loose their heat by radiant heat?  And if so does radiant heat emission always occur until the object is the same temperature as the surrounding or does it depend on other factors? Piping data through arbitrary functions in Clojure keep duplicates out of $PATH on source I have the following code that's source-d by my .shellrc  PATH="${PATH}:${HOME}/perl5/bin" PATH="${PATH}:${HOME}/.bin" export PATH   but if I make changes to other code and then source this file, my path continues to get longer and longer with each source, each time appending these when they're already there. What can I do to prevent this? Copy files excluding x,y,z causing error in shell script I'm not well versed in shell scripting but I imagine this to be a painfully easy fix but its eluding me.  I need to copy the contents of a directory excluding a number of files. I have a command that works when I enter it into the terminal, but when its run in a shell script it fails with a syntax error or just doesn't work.   The command in question is:  cp -r path/to/!(dir1|dir2|dir3) destination   Any help would be greatly appreciated! What is a glue record? This is a  about DNS glue records.   What exactly (but briefly) is a DNS glue record?  Why are they needed and how do they work? Keep "Employee" on the profile of SE employees on meta Currently, SE employees are given diamonds wherever they need them. I agree with  on this to some degree, employees shouldn't be treated any different.  But... on meta, employees are different. They have the power to dole out official responses, and thus we should be able to differentiate between an employee and a normal user. Currently, only some employees have a diamond on MSO (see , ). This makes it confusing, especially when you see official-sounding posts like .  Now, giving diamonds to all employees on meta may not be the best solution to this. I don't think all employees want their precious inboxes spammed with all the suspensions that are doled out on meta, and other mod stuff. They won't really need the diamond powers either (though it wouldn't hurt).  So, I propose this:  Similar to how moderators have "Moderator" clearly on their profile    display "employee" on an employee's profile, along with the diamond if they have one. At least on meta.    It would imho be even better to display it on their usercards in some form, but that has already been shot down.  It would be even even better if non-MSO mods had greyed out diamonds, similar to , but that's just me wanting more shiny stuff ;-) Linked account +100 rep bonus also applied to account with 200 How should I install HPLIP binary/proprietary plugin/driver for my HP printer or printer+scanner? Retain precision with double in Java Sorting hashmap based on keys Count total number of files in particular directory with specific extension I want to count the total number of files in particular directory that ends with ".mp4" extension.  I am getting following command:  ls -F |grep -v / | wc -l   It count all the files in particular directory, but I want the count of files that end with .mp4 extension.  Is there any Ubuntu command for that? Why, microscopically, is the voltage drop across a resistor affected by the current through it? If voltage is a potential difference, describing how much energy will be lost per unit charge as charge carriers pass through the resistor, why would the rate at which charge flows (i.e. current, $=dq/dt$) affect the amount of energy lost per unit charge?  I suppose I am asking why a quasi-"extensive" property of the system (current) would affect a quasi-"intensive" property of the system (voltage drop across the resistor).  Apologies if the answer is obvious; I was having trouble understanding why the rate of charge flow would factor into voltage drop whilst trying to rationalize Ohm's law for myself. Possible Duplicate:          I have seen  in SQL. I wonder how would you approach the opposite problem: splitting coma delimited string into rows of data:  Lets say I have tables:  userTypedTags(userID,commaSeparatedTags) 'one entry per user tags(tagID,name)   And want to insert data into table  userTag(userID,tagID) 'multiple entries per user   Inspired by  question  EDIT  Thanks for the answers, actually more then one deserves to be accepted but I can only pick one, and the  with recursions seems pretty clean to me. It works on SQL Server 2005 and above.   For earlier version of SQL Server the solution  can be used.  For working with text data type  will be helpful. Thanks again. Are players allowed to pass a penalty kick? Provide an easily discoverable way to get the full URL to an answer