Is it possible for a punch traveling at relativistic speeds to miss the target because of length contraction (from both reference frames)?
Hole-and-nail paradox in special relativity
Run a command without making me wait Hyphenation in compound adjectives Possible Duplicates:                In the sentence "Portland is known to be one of the most bike friendly cities in the US", is a hyphen necessary in "bike friendly"? As far as I know, the hyphen is only required when leaving it out would cause ambiguity. Wikipedia uses the example of "a small appliance factory" vs "a small-appliance factory".   As far as I can tell, the sentence above is pretty clear. A quick google search for "bike friendly city" brings up instances of both hyphenated and non-hyphenated usage. Thoughts?  Please excuse the poor formatting, sent from my iPhone. Connected to wifi successfully, but no internet connection Color gradient for bars in pgfplots I want that each bar in my diagram has a color gradient from black to white (from left to the right). However, for the following code, the gradient exists for the entire diagram such that the left bar is black, the middle one is gray, and the right one is white.   \documentclass{report}  \usepackage{pgfplots}   \begin{document}  \begin{tikzpicture}      \begin{axis}[ybar]          \addplot[left color=black,right color=white] coordinates {(1,2) (2,3) (3,4)};      \end{axis}  \end{tikzpicture}  \end{document} In Italian, when I write a sentence about an action (e.g. eating fish, playing), I would use the infinitive, such as  mangiare pesce fa bene alla salute (which literally is "to eat fish is healthy"), or giocare aiuta ad imparare (which literally is "to play helps to learn").   I would use the gerund in giocando si impara, but that would roughly mean "When playing, you learn." and in this case the infinitive would not be correct. (Giocare si impara is not what you would say in Italian.)  Should I use the infinitive, or the gerund, in sentences similar to the following ones?   To play with fire is dangerous. To win the lottery is just a matter of luck. To escape from Alcatraz is impossible. To practice makes you perfect.   Is the infinitive always wrong, when the verb is the subject of a sentence? Modelling with more variables than data points I'm fairly new to Machine Learning/Modelling and I'd like some background to this problem. I have a dataset where the number of observations is $n&lt;200$ however the number of variables is $p\sim 8000$. Firstly does it even make sense to consider building a model on a dataset like this or should one consider a variable selection technique to start with such as ridge regression or Lasso? I've read that this situation can lead to over-fitting. Is that the case for all ML techniques or do some techniques handle this better than others? Without too much maths a simple explanation on why the maths start to breakdown for $p&gt;n$ would be appreciated. Why was Sirius ever convicted? Computer wont boot to windows I recently installed a Linux operating  system (backtrack 5 r3) I couldn't connect to the internet with it so I removed the partition manually. After that, whenever I turn on my computer it goes to a command line that says "error no File-system found" "Grub Rescue/"  I have tried f12 and booted into all the options. I also put Ubuntu 12.04 on my flash drive and tried installing it on the computer, the installation failed saying "No Available Space"  My hard-drive is 500g with about 250 left. I put the hard drive in another computer (as a secondary just to see the files. It had 2 partitions a main and one with 1 gig. I formatted it with no difference.  My Problem: I can't boot into Windows Apparently this is a  and should hopefully be fixed in an upcoming update.    I have installed SQL Server Management Studio v17.9 on a clean Windows 10 installation.  This associated all .sql files with SSMS.  I want to associate .sql files with a plain text editor (eg: Sublime) but I am unable to change the default application.  I have tried:   Right click .sql file -> Open With -> Sublime + "Always use this program". Settings -> Default Applications by File Type -> Find .sql -> Change to Sublime Right click .sql file -> Properties -> "Change" button -> Sublime. Using ftype via elevated command prompt as seen    In all 3 cases, my selection is not reflected in any way, anywhere.  The icon remains SSMS, and the file opens with SSMS.  Is there some kind of "File Association retention" setting within SSMS I am unaware of?  Edit: I can change the default application for non-SSMS-associated extensions without issue.  Edit: after deleting registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.sql, .sql files show a VSCode icon:    If I then double-click New Users.sql, it opens with SSMS and a refresh of regedit shows the .sql entry recreated with ssms.exe associated (the icon remains VSCode):    If I then right-click -> open with -> Choose Another App -> Select Sublime and hit "Always use this to open .sql files", it opens with Sublime and a refresh of regedit shows a new "b" entry created for Sublime.  The icon remains VSCode, and double-clicking opens it in SSMS:    If I then delete the a entry for ssms.exe and rename b -> a such that only sublime exists, then double-click the .sql file, it opens with SSMS and generates a new b entry for itself: Possible Duplicate:          On Windows I am able to switch between keyboard layouts by pressing Alt+Shift. Is there a similar keyboard shortcut in Ubuntu? Fastest way to convert string to integer in PHP Unable to send mail to hotmail from rackspace cloud How can I convert JPG into PDF easily? Differences between pure/mixed/entangled/separable/superposed states How to discard unsaved changes to a view when editing it leads to a WSOD? Why can we apply the $E=hf$ equation for electrons? So in my textbook, it states that the $E=hf$ equation applies to electrons, and all particles, not just photons.   But in order to prove this, wouldn't these particles need to have zero mass, to satisfy $E=pc$ from Einstein's equation?  In Einstein's theory of relativity $E^2= p^2c^2 + m^2c^4$, we get $E=pc$ because we consider the mass to be zero.   For $E=hf$ to work for other particles, don't we need to assume electrons have zero rest mass? $X$ is a topological space with no special properties.  If a space $X$ has no isolated points, then show the same for any dense subset of   $X$.  Thanks a lot. Show $1/(1+ x^2)$ is uniformly continuous on $\Bbb R$. Whether and how to thank a girlfriend or boyfriend in the acknowledgements of thesis? How is it received by the academia if someone thanks to his/her girlfriend/boyfriend in the acknowledgements of the thesis?  I have seen writers including his/her fiancee in the acknowledgements, however I don't know if including an informal relationship in the thesis will be received well.  If it is acceptable, how should I refer to my girlfriend? iptables drop all incoming ICMP requests except from one IP Currently, I have something like:  iptables -A INPUT -p ICMP --icmp-type 8 -j DROP iptables -A INPUT -s x.x.x.x -p ICMP --icmp-type 8 -j ACCEPT   However, when I run the second command, it looks as if iptables just stops.  I have to break out of it to get back to terminal.  Perhaps I am doing it all wrong, but some insight would be helpful.