Is the speed of gravitational waves constant in all inertial frames? If so, why isn't this included as one of the postulates of special relativity?
A thought experiment: Imagine the Sun is suddenly removed. We wouldn't notice a difference for 8 minutes, because that's how long light takes to get from the Sun's surface to Earth.   However, what about the Sun's gravitational effect? If gravity propagates at the speed of light, for 8 minutes the Earth will continue to follow an orbit around nothing. If however, gravity is due to a distortion of spacetime, this distortion will cease to exist as soon as the mass is removed, thus the Earth will leave through the orbit tangent, so we could observe the Sun's disappearance more quickly.  What is the state of the research around such a thought experiment? Can this be inferred from observation?
jQuery selector regular expressions First let me explain what I mean by "transitive" Suppose that the price of product A and the price of product B has a correlation of .5 Suppose also that the price of product B and product C has a correlation of .5  One might thing that if correlation(A,B) = .5 and correlation(B,C) = .5 then correlation(A,C) > 0, but with an intuitive example we can see why this is not the case:  Suppose that A is a fruit salad made of papaya and banana, suppose also that B is a fruit salad made of banana and strawberry and, finally, suppose that C is strawberries and cream. Clearly, when the price of banana goes up, both the price of A and B will go up; when the price of strawberry goes up the price of B and C will go up; but since A and C have no ingredients in common, their price isn't correlated.  My question is which statistical concept captures this intuitive idea. Is it the concept of dimensions?  What do I mean by transitive? Let me define the binary operator X corr? Y as 1 if correlation(X,Y) != 0 and 0 otherwise, so:   A corr? B = 1, B corr? C = 1, but  A corr? C could be = 0   If corr? was transitive, then A corr? C = 1 I tried to write , but I couldn't find any simple explanation page to link to. I ended up garbling a home-spun description of my own with a not-terribly-helpful image from 2012.  This  puts it better than I can:     As a new user in 2015 can there please be more information about what is WinterBash. The link took me to a bunch of stick figures running around making (I think) numbers (I think its a countdown clock). It doesn't explain the event or even what a hat is. – Ian Miller Dec 4 at 2:58   All I found on Meta was dead links. For example,  was downvoted to -2 and answered with a link to an FAQ page that no longer exists. If $a, b, c$ be distinct reals such that $$a + \frac1b = b + \frac1c = c + \frac1a$$ how do I find the value of $abc$?  The answer says $1$, but I am not sure how to derive it. It's possible to offer and award bounties of reputation on questions.   What is a bounty? How can I find questions that have a bounty attached? How do I start a bounty? When can I start a bounty? Why is the system requiring me to choose a bounty amount that's higher than the minimum? Can I use Markdown formatting in the bounty remarks? Can I edit the remark? How long is the bounty period? How do I award a bounty? Can I award a bounty to my own answer? Can I award a bounty to an old answer? If I offer a bounty on someone else's question, can I award the bounty to their answer? After awarding the bounty, can I remove it or move it to another answer at a later time? What happens if there's no answer after the bounty period? What happens if I feel my question is still unanswered? What is automatic awarding? Are bounty awards exempt from the 200 points/day reputation limit? How does Community Wiki mode affect bounties? How does user deletion or post dissociation affect bounties? Can I award a bounty to an answer from a deleted user or one where the author was dissociated? Can I offer a second bounty after the first one has expired? Can I raise my bounty? What happens if a bounty question is closed or deleted? Why can't I vote to close or migrate a bounty question? What happens if I delete my account while I have an active bounty? Do I keep an awarded bounty when I delete my answer? What happens if a question where I awarded a bounty later gets deleted or migrated? Can I cancel my bounty? Can I affect / divide / share part of my bounty to two (or more) users? How many outstanding bounties can a single user have?      See also:  in the Help Center Compton scattering vs. photoelectric effect Say a photon hits some atom.  What determines whether there will be a photoelectric effect (photon is absorbed, electron is released) or whether there will be a Compton scattering (the photon is  scattered at some angle, and the electron is released with another direction)? In the movie, there's one scene that seems very strange to me.  First, the point:  When the team gets in the first level, they find out that Fischer has a militarized subconscious. After they freak out, and argue about it, they also find out that they can't die, otherwise they'd get stuck in limbo.  So, when Eames says that he won't go further, Cobb states that, since the first level sedative will last a week they would be killed. They needed to go on to the next levels as fast as possible, so the combined multi-level kick would make them wake up.  Here's the point: The plan was the multi-level kick would wake them up before the sedative was off     Ariadne: ...is ten years! Who would wanna be stuck in a dream for ten years?   Yusuf: Depends on the dream.    Arthur: So, once we've made the plant, how do we go out? Hope you have something more elegant in mind than shooting me in the head?    Cobb: A kick.    ...   Arthur: Are we going to feel a kick with this kind of sedation?   Yusuf: Well, that's the clever part. I customize the sedative to leave inner ear function unimpaired. That way, however deep the sleep, the sleeper still feels falling, or tipping.     Now, the question:  When they finish the job, they perform the kicks   The van hits the water Arthur detonates the elevator Eames explodes the fortress   But they don't wake up. They are back in the drowned van. So, as far as I could understand, they still had to sit and wait for the first level's week to end.  (We see Fischer talking to his godfather)  Why didn't they wake up with the kicks, as it was planned? And how did they managed not to get killed by Fischer's projections after they got out of the Van? Is it possible to install Ubuntu on my Windows 8 computer without any CD or USB drive? Please read entire post CAREFULLY before answering.  This question will make you confused if you don't.  Information (May skip :P)   OS : Windows NT 6.2 (Windows 8 K) Equipped hard disk   Total 1TB, 1 disk C: (Simple Layout, NTFS, Boot, Pagefile, Crash dump, Main): total 488,039,776,256 bytes, used 93,473,599,488 bytes D: (Simple Layout, NTFS, Main): total 486,859,075,584 bytes, used 8,426,016,768 bytes hidden: Ask if needed  Brand(manufacturer): Samsung Electronics Processor(CPU): Intel(R) Core(TM) i5-3230M CPU @ 2.60GHz RAM: 8GB , 64-bit , OS 64-bit   Question (READ THEM ALL VERY CAREFULLY)   Is there any way to install Ubuntu on this computer without any external disk (CD, USB drive, etc) Note : This computer is 64-bit, so  did not help me. WUBI does not support UEFI, and This computer uses it. No Virtual PC programs like VirtualBox or VMWare, because it takes memory.   EDIT : I already found a USB drive in my home, so now it is installed on my computer xD What are the Windows A: and B: drives used for? In Windows you have a C-drive. Everything labeled beyond that is with the following letter.   So your second drive is D, your DVD is E and if you put in a USB stick it becomes F and the following drive G. And so on and so forth.  But then, what and where are A and B-drives? Convert and redirect URL in uppercase to lowercase using .htaccess I would like to redirect a URL with uppercase characters http://localhost/A/B to a lowercase version http://localhost/a/b using the .htaccess file. Using regex I can capture A and B but is it possible to convert them to lowercase? Changing precision on a column in the attribute table without losing data? I have data in an Excel file that I want to join with a shapefile in my project. The Excel file contains values like volumes. The Excel file and the shapefile I want to join it with both contain the same property names.  The problem is, when I join the two, I get too many decimals in the attribute table. I get six, but I only want it to be one.  I tested to change the format of the cells to one decimal, and then I saved the file as *csv. But, somehow I seem to loose data in the process? It should be 42 rows that contains data in the column i am working with, but I end up with only like 10?  Another thing is that my property names contains the letters Å. Ä and Ö, perhaps this complicates things?  I read the question , but it doesn't mention the problem with the data loss.  My question was tagged with , but I didn't write what version I'm using. I use QGIS 2.2.0. Would it help to upgrade to the latest version? Factorizing polynomials over fields other than $\mathbb{C}$ I currently only have remote access to this CentOS box, I need to move /var form the primary RAID to a new set of disks that was installed with more space, My current thoughts on how to accomplish this is to temporarily mount the new RAID to /tmp/var. rsync everything from /var to /temp/var then modify the fstab to point /var at the new disks.  Here is my question. how do I delete the existing /var on the primary disks once I have the new disks mounted to that location (assuming this is even possible remotely)? In this MWE, I want to obtain bold letter for the letter "H" (compare the two "H") :  \documentclass[10 pt]{beamer} \usetheme{default} \usepackage{lmodern} % load a font with all the characters \usepackage{fontspec} \usepackage{cmbright} \SetSymbolFont{largesymbols}{normal}{OMX}{iwona}{m}{n} \usepackage{amsmath}%loads amsmath that should go before unicode-math \usefonttheme{professionalfonts} \defaultfontfeatures{Mapping=tex-text}  % This seems to be important for mapping glyphs properly  \begin{document} \begin{frame} \[ \mbox{First bold H : }\|x\|_{\mathbf{H}},\; \mbox{Second bold H : }\mathbf{H}  \] \end{frame} \end{document}   but I don't know how doing it. THe "H" produced by this MWE is tiny but no bold effect. If I use      \SetSymbolFont{largesymbols}{normal}{OMX}{iwona}{m}{n}   I obtain bold tiny "H" but the font used still not the same. Speak Slower or Speak Slowlier? AFAIK the correct grammar for "speak slow" is "speak slowly" (slowly being an adverb). Please correct me if I am mistaken.  But in daily life I have not heard anyone saying "Speak slowlier".  I think I heard folks saying "Speak slower" but I also think it is incorrect.  Which is the best or correct form to convey the message?  Could that be the longish "Speak more slowly?" How to import Apple Mail archive files in Outlook 2013? I need to import Apple Mail archived files in Outlook 2013 on Windows, but every time I open the import wizard and reach the file selection step, I cannot select the archived file. It doesn't even show in the dialog box.  I don't know what the issue is. Is it the file size issue as the archive file is large (about 7 GB) or there is any other fault? Notify question OP (and those who marked it a favourite) if an answer has been modified Seriously, I had not noticed e.g. Jeff's edit  had he not also retagged my question. Norms Induced by Inner Products and the Parallelogram Law startsWith() and endsWith() functions in PHP So I can start from len(collection) and end in collection[0].  I also want to be able to access the loop index.