How do Black Hole event horizons grow?
How can black hole increase its mass?
Gradle compiling slows down my computer The responsiveness is really bad on a newly installed Ubuntu 14.04 LTS.  Here's the specs of my laptop:  Quadcore Intel i7-4600U CPU @ 2.10GHz 12GB Ram 1TB Samsung EVO SSD   And when gradle is compiling, my entire system slows to a crawl, videos begin stuttering, browser scrolling lags... etc.  The same goes when a page refresh occurs in another window in Chrome, and while it refreshes, the HTML5 video in another tab begins stuttering.  How can I fix this?  Here are some logs:  $ vmstat -a 1 5 -   $ iostat -x 1 5 -   $ top -b - How to make an alias permanent? I have created an alias:  alias shh='sqlplus hfdora/hfdora@hfd1"     After creating this alias I was able to enter my database only by typing shh.  But after closing my shell, I wasn't able to find the alias next time. Even after typing only alias, shh was not showing in the list.  Is there any file to make an alias permanent so that it will not be erased? Why am I getting black photos when I use the Manual feature on my DSLR? I was taking photos a few days ago, and I had it set to Manual. After about four photos, the rest started coming out black. I could see through my eyepiece clearly, and it took the photo normally, but when I reviewed it they were all black. Cannot login to chat.meta.stackexchange.com; server error when trying to access chat homepage I just recreated my MSE account after having deleted it a few years ago. Now, I'm trying to log in to Meta Stack Exchange Chat, and whenever I try to do so, it just fails silently and I'm still logged out.  Additionally, in the same browser session that I'm supposedly logged out, I get a server error when accessing the chat homepage or the chat profile page of any user. I don't get any errors when trying to access any of these pages in a private session. I also was able to sign in to Stack Exchange Chat and Stack Overflow Chat without problems, since my accounts on SO and my parent site for SE chat haven't been deleted.  I think it might be because it's trying to sign me in to my old chat profile, which was not deleted, but that is associated to my old, deleted site account, which clash and thus cause it to fail. Can a dual national visit USA under VWP after visa refusal for other nationality? Recently I was refused an E-2 visa under Section 214b. To be honest I don't really know why because I have strong ties with my home country (house, bank account, family) so my lawyer sent an appeal to the legalnet and I'm  waiting for an answer.  I have a second nationality that I used to travel in USA within the last 15 months under ESTA. A few days after my E-2 refusal I checked my ESTA status  and it is still authorized.  Can I travel to the States right now or not?  I have a purchased business over there and have to take care of my assets. Are there any more Asgardians? I have hundreds of figures with filenames containing "#" to include using \includegraphics, I've tried packages like grffile or currfile, but none of them work. Can anyone suggest a real solution so that I don't need to change hundreds of file names? Thanks.  Update: 1. I'm using Windows. 2. When I compile it, it shows "Illegal parameter number in definition" How to make a disk image and restore from it later? How do you set, clear, and toggle a single bit? How do you set, clear, and toggle a bit? Ubuntu doesn't boot! What is difference between a ring and a field? Is it possible to switch from one area of graduate study to another in US universities? For example, suppose someone has enrolled in a computer science phd program. Can he switch over to math(or physics) phd program in the same school later?(or say from applied mathematics to pure mathematics?)  What are the steps for doing for doing that? mv : not found when executed from script that modifies PATH variable I have this in my script. But is returning an error. If I execute the command in the console works fine  ./script.sh[16]: mv: not found [No such file or directory]   I want move some files what starts in T353 from one folder to another. REMOTE_PATH is /tmp/ and PATH is my working directory  cd $REMOTE_PATH mv T353* $PATH #this is the line 16   If I make mv /tmp/T353* . works fine. As the output of df -h shows here, something is eating up 5GB of free space. So, it's not available to use.   I'm also noticing sometimes that the hard disk gets filled up to 100% sometimes. So, I had to restart the machine or delete some unncessary files. Only noticed these in /home partition. Don't know whether these two are related, but appreciate if anyone can put some insight into this.  $ df -h Filesystem            Size  Used Avail Use% Mounted on /dev/sda8             100G   92G  2.7G  98% /home How did Luke know where to land on Dagobah? Prove $\int_{a}^{b}{f(x)dx}>0$. Let $f\ge0$ be integrable on $[a,b]$. Let $f$ be continuous on $x_0\in (a,b)$ and let $f(x_0)&gt;0$.   Prove $$\int_{a}^{b}{f(x)dx}&gt;0$$  It is easy to see it, graphically, because $$f\ge 0 \Rightarrow\int_{a}^{b}{f(x)dx}\ge0$$  and if $f&gt;0$ somewhere between $a$ and $b$, then the zone of $F$ between those point is "real" (positive) and $\ne 0$.  My problem is, how do I show it formally?  I would appreciate your help. Does removing an application from Software Center do a remove or a purge When I remove an application already installed through the Software Center. Does it remove the app the same way as doing a purge to it (aptitude purge) or does it remove it like a "remove" (aptitude remove). How can I produce an encrypted Swap Partition for 14.04 ? All the advices I saw here are for versions &lt;14.04 and do not work for me.  I tried a lot but nothing lasted longer than a reboot.  On installation I decided to encrypt my home and 9 GiB partition for swap but this swap was never used by Kubuntu. Gparted finds an "unknown filesystem".  I many times formated it as swap, edited fstab and crypttab and used all the tricks mentioned in different answers here. The often mentioned PunyGeek letter does not work for me probably because /etc/initramfs-tools/conf.d/resume does not even exist on my system. I am planning a trip to Italy this coming January. My plan is to land by plane in Roma and then go to France by train/bus stopping in some Northern Italian cities on the way, enjoying the architecture, the atmosphere, the art and and the food.   I want to do it at my own pace, without heavy scheduling. Ideally, I would just decide which cities to visit, and take a train whenever I feel it. I often do this here in South Korea where I am living, taking advantage of the "standing seats" as it is called here, that is travelling (for a cheap price and no reservation) standing on the romm between two cars. From my experience, it is also doable in Taiwan (at least in some trains).  In France, regional trains usually does not need any reservation, so you can buy a ticket and take the train whenever you want.  Can I expect a similar system in Italy, that is a way to make short travels between close cities without reservation?   Example of "short travel": Pisa - Firenze. Find all primes $p$ such that  $ p^3-4p+9 $ is a perfect square.   I tried a few different values for $p$, namely $2,3,5,7,$ and $11$. The prime $p =2,7,11$ all worked but $p =13$ didn't so it makes me wonder. How can I find all primes such that it is a perfect square?  EDIT: it turns out this is problem P25 in post number #63 at