Someone asked the following question in a post to the moderated newsgroup sci.physics.research, which is mirrored here at PF: Anyone quoting a Wikipedia article in any forum (whether a UseNet post or a PF post) should always link to a specific article and version. Fortunately, I happen to know where the quote comes from, but first let me stress an critical point: since anyone can edit (almost) any Wikipedia article at any time, they tend to be unstable, especially if they concern a topic currently in the news, and this can adversely affect their utility for those seeking relevant and reliable information on some topic of interest. As it happens, many months ago, I inserted some material into the Wikipedia article on "gravitational radiation" specifically because I had noticed several (then) new instances of the same confusion which prompted dharrington's recent question in sci.physics.research. One version which includes most of the material I inserted at that time is http://en.wikipedia.org/w/index.php?title=Gravitational_wave&oldid=51809685. (Notice that this url links to a specific version of a particular Wikipedia article.) The list of examples of more or less idealized situations was specifically intended to address the confusion expressed by dharrington and many others before him. A more recent version (as I write this post) is http://en.wikipedia.org/w/index.php?title=Gravitational_wave&oldid=92428181 Comparing these two versions, you can see that someone removed much of the material I had inserted, and unfortunately the new version once again perpetuates the specific confusion which I had worked to prevent. (In fact, it makes some claims which are incorrect, but readers who care about such things will probably be able to spot these without my help.) This unfortunate episode is by no means unusual and I feel that it aptly illustrates why the slogan claiming that "wiki articles tend to improve monotonically toward a state of perfection" is fatuous nonsense, and indeed expresses a potentially dangerous misconception concerning the utility of Wikipedia as an information resource. It should also help to explain why anyone offering a link to a Wikipedia article should make sure to hit the "permanent link" button in the sidebar, so that they link to the specific version which they read. The answers so far offered in sci.physics.research also fail to point out what dharrington needs to know (unfortunately, now that s.p.r is populated mostly by non-physicists, who often want to discuss scientically dubious speculations but lack the background neccessary to discuss serious physics intelligently, it is much less valuable for serious students than it was even five years ago.) Fortunately, any good gtr textbook, for example Schutz, A First Course in General Relativity, will explain in detail the relevant points: 1. Production of gravitational radiation is best studied (at least in elementary courses) in the context of the "quadrupole radiation approximation", which belongs to the domain of "linearized gravity", aka the weak field approximation to the EFE (which is highly nonlinear). 2. According to the quadrupole radiation approximation, the strongest type of gravitational radiation from an isolated concentration of mass-energy occurs when the quadrupole moment tensor of the source of the field has a nonzero second derivative. The energy emitted per unit time, or power, is estimated by the "quadrupole radiation formula". 3. In the older version, I listed sufficiently many examples to illustrate what these remarks imply in practical terms; unfortunately, these do not appear in the more recent version. (I should perhaps explain that I am no longer participating in Wikipedia because of my concern over its lack of any concept of "information integrity", much less effective mechanisms to protect good articles from being easily degraded, but see http://en.wikipedia.org/wiki/User:Hillman for my former Wikipedia user page. I explained above why I no longer participate in sci.physics.research. The presence of dedicated and knowledgeable moderators at PF is an essential part of what makes this forum work! At least for now...) This survey article (an invited contribution to Living Reviews) might be a good place to start: http://www.arxiv.org/abs/gr-qc/0311082 See also the problem on the number of gravitons produced by a breaking light bulb in the problem book by Lightman et al. Enjoy!