Does getting hit by a gravitational wave hurt?
How close would you have to be to the merger of two black holes, for the effects of gravitational waves to be detected without instruments?
Why Changing Permissions For Some Systems Files is Not Allowed? Story about human space explorers who run into alien telepath space crew I read a short story in an anthology around 1998 (the book could have been older than that) which went like this - A human space exploration scientific crew is exploring an alient planet (peaceful planet, as I recall) when they run into an alien spaceship (from a different planet which also happened to be there) - the aliens were telepaths.   The alien commander and first officer discuss the earthlings after a meeting and realize that the human crew are the descendants of a species (Banthu/Klanthu/Zantha, something like that) which had tried to violently take over the galaxy some 20/30/50,000 years ago and which had been beaten back by the combined might of the rest of the galaxy. They had supposedly been eliminated but they somehow managed to survive and are back in space only a few thousand years after they were completely beaten (which is something the aliens are amazed by).   The alien commander kills the human explorers via telepathy but realizes that there is no information available to locate their home planet and speculate that they will be meeting again soon given the past history of the humans.  I vaguely think there was also a fantasy short by L Sprague de Camp in the same anthology, but can't be 100% sure. Any thoughts/ideas? Thanks! Where was Alastor Moody during Harry Potter and the Half Blood Prince? Test Class Apex Page Parameters How do I install Java? How do I install Java, including in my browser, so websites with Java work? Well, I already searched meta as well as cleared my browser cache.  I realize this may be a SO cache problem, but it still seems kind of strange to me.    The deleted question is (assuming it still exists).  Shouldn't deleted questions only be visible to 10k users?  I'm only at 2k. How can I write the name show in axis of 3D array using TiKz I am drawing a 3D array like the attached picture, which actually describes a multidimensional array. However, I can not put the name of the axis and take the value from the matrix like the attached picture.  This is the code that I have:  \documentclass[margin=5mm]{standalone} \usepackage{tikz} \usetikzlibrary{matrix,calc}  \begin{document} \begin{tikzpicture}[every node/.style={anchor=north east,fill=white,minimum width=1.4cm,minimum height=7mm}] \matrix (mA) [draw,matrix of math nodes] { (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ };  \matrix (mB) [draw,matrix of math nodes] at ($(mA.south west)+(1.5,0.7)$) { (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ };  \matrix (mC) [draw,matrix of math nodes] at ($(mB.south west)+(1.5,0.7)$) { (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ (1,1,3) &amp; (1,1,3) &amp; (1,1,3) &amp; (1,1,3) \\ };  \draw[dashed](mA.north east)--(mC.north east); \draw[dashed](mA.north west)--(mC.north west); \draw[dashed](mA.south east)--(mC.south east); \end{tikzpicture}   \end{document} Change edit approval threshold to (# approve − # reject ≥ N) Currently, the threshold for approving or rejecting a suggested edit is , whichever is reached first.  This means that, when  or just  edits get approved, it's often with a vote count of something like 1 reject / 2 approve (or 2 reject / 3 approve on SO).  Typically, these edits manage to get one or two very quick approve votes from, um, , after which it's very hard for the slower and more careful reviewers to accumulate enough votes to catch up before the edit is approved.  Conversely, when a valid edit gets wrongly rejected, this very rarely happens unanimously either.  More often, you'll see something like 3 votes to reject / 2 to approve, but that single last vote, no matter how well or poorly considered, is enough to tip the scales.  So I'd like to propose a simple change to the approval / rejection threshold:        Suggested edits should be approved when S = (# of approve votes &minus; # or reject votes) &ge; N, where N = 3 on SO and N = 2 on other sites.   Similarly, suggested edits should be rejected when S &le; &minus;N.      No, this change is not going to magically fix all the problems with suggested edit review.  But I believe that it would be a simple and conservative improvement over the current behavior:   For obviously good or bad edits that get approved / rejected unanimously, this suggestion would not change the current behavior in any way. For edits that get one mistaken or careless reject / approve vote (as happens pretty often), an extra approve / reject vote would be required to balance it.  This would slightly slow the review process for such edits, but not excessively so.  Further, I would argue that these are precisely the kind of edits that deserve that little bit of extra attention to make sure the eventual decision will be correct. Edits that are truly controversial, and for which the reviewer community is nearly exactly 50&ndash;50 split between voting to approve and reject, might stay in the review queue significantly longer (maybe twice as long on average) than under the current system.  However, this is a trade-off for the increased likelihood that the eventual decision will actually reflect the majority opinion among reviewers, rather than mere random chance.  In any case, even if reviewers are exactly 50&ndash;50 split, the  under the proposed scheme is only N&sup2;, i.e. 4 votes for other sites and 9 votes for SO.  Even a slight bias in the voting will further reduce this.  Besides, the longer the suggestion remains in the queue, the more likely it gets that someone will short-circuit the process by casting a binding vote (mod / post owner) or by choosing to improve the edit.     Ps. If it is felt that there's an issue with , a simple further chance to address that could be to make each reject vote count as, say, &minus;2 rather than just &minus;1 approval votes (and change the rejection threshold to S &le; &minus;2 &times; N to compensate).  This still wouldn't help with bad edits getting unanimously approved (which isn't really something that can be fixed, except maybe by slugster's cattle prod), but it would mean that each reject vote would now effectively cancel out two approve votes, titlting the balance for disputed edit suggestions in favor of rejection and making it easier for more careful reviewers to counter the "robo-approvers". After writing the FreeNAS IMG to a 16 GB USB flash drive, I can now only use 938 MB. I used the Win32 Disk Imager tool to write the IMG to the device. Then later, when I inserted the the USB drive into my Windows 7 computer it said that it had to be formatted, because it couldn't read it. I believe this is normal. So I formatted it inside Windows using the format option when prompted. So in Windows Explorer now, 938 MB is reported as capacity of this device.    Also, when i check the properties dialog box I can see the same numbers.    And when I check with diskmgmt.msc I can see there are several volumes I don't recognize and unallocated space of 12.79 GB.    Now, I have another 2 GB USB flash drive with the same problem. It too was used for FreeNAS, and it too has a reported capacity of only 938 MB. I thought it was broken there for a while, until I saw the same problem with this 16 GB model.  I tried using diskpart on the 2 GB model, and I saw that there were several partitions there (list partitions) just like on this one. So I used the clean option to try to wipe it, but that wiped off everything so it's totally useless now. I'm not sure how to rebuild it.  Is this a standard routine, like part of the whole "user experience", that whenever you make a bootable USB falsh drive with FreeNAS, it messes up your device? I am new to FreeNAS, so i wouldn't know. But it sure looks like it. Maybe it is in fact the format operation in Windows that messes things up... I don't know. It's not very nice.  How do I restore the capacity back to 16 GB-ish (14.9 GiB)? Non-abelian group $G$ satisfying $(a \cdot b)^i=a^i \cdot b^i,$ for two consecutive integers. Given an example of a non-abelian group $G$ satisfying $(a \cdot b)^i=a^i \cdot b^i, \forall a, b \in G$ for two consecutive integers.   This is question 5 from Herstein Page 35. I have proved that conclusion holds for three positive integers.Thanks. Does the universe have an edge/boundary/barrier? If yes, what is at the edge? My question related kind of to asking what the shape of the universe is. Say a hypothetical alien civilization built an faster-than-light spaceship. If they keep flying would they end up where they began? ie space itself is curved...or would they hit some invisible barrier? Make voting activity on your posts available on site metas (what you would get from rep if metas had rep) Child metas don't have rep, so there's no point in tracking a rep stat or reporting changes.  But one of the things rep updates do on main sites is to alert me when there's activity on older posts.  On metas, unless I revisit a question I'll never notice that there's been a bunch of voting (which might be accompanied by new comments that didn't ping me).  I'd like to know about that activity, not because of any ego reasons but because meta is where site policies get discussed and set and it's useful to know about changes in the community will.  A couple days ago I visited a meta post where, a few weeks ago, my answer had been voted down, and this time it was at the top.  Could we have something like the reputation-changes tab on meta?  I suspect that the data already exists, because I once  (and I see I'm not the only one).  If something akin to reputation is already being tracked internally on per-site metas, can we get it exposed? The Definitive C++ Book Guide and List This question attempts to collect the few pearls among the dozens of bad C++ books that are published every year. Unlike many other programming languages, which are often picked up on the go from tutorials found on the Internet, few are able to quickly pick up C++ without studying a well-written C++ book. It is way too big and complex for doing this. In fact, it is so big and complex, that there are very many very bad C++ books out there. And we are not talking about bad style, but things like sporting glaringly obvious factual errors and promoting abysmally bad programming styles. Please edit the accepted answer to provide quality books and an approximate skill level — preferably after discussing your addition in . (The regulars might mercilessly undo your work if they disagree with a recommendation.) Add a short blurb/description about each book that you have personally read/benefited from. Feel free to debate quality, headings, etc. Books that meet the criteria will be added to the list.  Books that have reviews by the Association of C and C++ Users (ACCU) have links to the review. *Note: FAQs and other resources can be found in the  and under . How to clear the BIOS security password on this notebook? I recently got an Acer Aspire E11 (E3-112m) and in order to install another OS I had to set a Supervisor password, so I used a well known password to me, the problem is that such password contains a special character ! which the password prompt won't let me input, though it let me when I had to set the password (buggy prompt I believe). Now everytime I need to change something in the BIOS I have to fail 3 times and go to  to generate a master key.  I have already tried several different methods to clear it:   Removing the CMOS battery Looking for the reset jumper (which doesn't even exist).   I also noticed there were 2 weird buttons on the front and back sides of the motherboard, I don't know what they are for but I also pressed them (while both the CMOS and the regular battery were disconnected). All of this without luck, the password just won't reset (though the RTC did).  Are there other ways to reset the Supervisor/Admin password on this model? Can I partition a HDD for playing Xbox 360 games? I am planning to buy an xbox 360 console. my budget permits me acess to only the 4 GB one which needs extra space for many games' install. I have an external HDD of size 40GB. My question is can I divide it into partitions such thet I can use one for gaming on xbox and the other for data storage. How to open a PDF file from terminal? I used to work on the Mac terminal before and I used:   open file2open.pdf   and the PDF file would be opened on preview or whatever my default viewer was. When I use it in the terminal in Ubuntu I get this error message:   Couldn't get a file descriptor referring to the console Unable to mount ISO in write mode The  tag doesn't appear to be very useful.  It's used in a variety of ways (for reading, writing, showing, transforming, compiling, translating, obfuscating, obtaining, ... source code) on 1747 questions right now, and doesn't appear to be adding any classification value to the site.  Can we get rid of it? Simplify $\prod_{k=1}^5\tan\frac{k\pi}{11}$ and $\sum_{k=1}^5\tan^2\frac{k\pi}{11}$ My question is:  If $\tan\frac{\pi}{11}\cdot \tan\frac{2\pi}{11}\cdot \tan\frac{3\pi}{11}\cdot \tan\frac{4\pi}{11}\cdot \tan\frac{5\pi}{11} = X$ and $\tan^2\frac{\pi}{11}+\tan^2\frac{2\pi}{11}+\tan^2\frac{3\pi}{11}+\tan^2\frac{4\pi}{11}+\tan^2\frac{5\pi}{11}=Y$ then find $5X^2-Y$.  I couldn't find any way to simplify it. Please help. Thanks. I have this struct:  struct Map {     public int Size;      public Map ( int size )     {         this.Size = size;     }      public override string ToString ( )     {         return String.Format ( "Size: {0}", this.Size );     } }   When using array, it works:  Map [ ] arr = new Map [ 4 ] {     new Map(10),     new Map(20),     new Map(30),     new Map(40)};  arr [ 2 ].Size = 0;   But when using List, it doesn't compile:  List&lt;Map&gt; list = new List&lt;Map&gt; ( ) {     new Map(10),     new Map(20),     new Map(30),     new Map(40)};  list [ 2 ].Size = 0;   Why?