Wikipedia talk:WikiProject Physics/Archive September 2016
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There's a plasma aerodynamics which currently points to plasma actuator. Seems like it should point somewhere else? The aerodynamics of superheated hypersonic travel through the atmosphere doesn't seem to be covered at the target. -- 65.94.171.217 (talk) 07:09, 9 September 2016 (UTC)
Some changes to vital articles
Please comment here. 21:18, 17 September 2016 (UTC)
- In the off chance your browser doesn't forward to the proper section, it's 10.1.1 in the TOC. Primefac (talk) 21:30, 17 September 2016 (UTC)
Feedback on RF resonant cavity thruster
Could someone take a look at the article and help improve its description of relevant physics & the experiments done to date? It is a case study in experimental design, error margins, and knowing when there is enough data to say something useful about new but a priori extremely unlikely events/discoveries. It keeps coming into the public eye, so it would be good for the article about it to be decent. Maybe most relevant to comment after the publication of the first real paper on the topic, in December. – SJ + 03:47, 21 September 2016 (UTC)
Help, please: prediction or result?
(Please see Talk:Retrocausality § Out of date article.)
The slide on p.15 of John G. Cramer's 2009 publication "Quantum Optics and Retrocausality: Investigation of the Possibility of Nonlocal Quantum Communication with Momentum-Entangled Photon Pairs (1997-now)"[1] seems to be presenting an actual result:
- The H-polarized entangled photons have no optical delay, and the signal is received as soon as these photons are detected at D1,2, which is about 50ms before the signal is transmitted, when the twin entangled photons arrive at D3,4.
But the same slide is included, apparently as a predicted result, on p. 30 of his 2007 "The UW Nonlocal Quantum Communication Experiment".[2]
Can someone who understands the subject please assist?
Please {{Ping}} me to discuss. --Thnidu (talk) 16:31, 19 September 2016 (UTC)
- Recent papers. Note the negative results, both experimentally and theoretically, for nonlocal or retrocausal signaling. BrightRoundCircle (talk) 11:40, 21 September 2016 (UTC)
- ^ Cramer, John, (2009-09-11). Five Decades of Physics. "Quantum Optics and Retrocausality: Investigation of the Possibility of Nonlocal Quantum Communication with Momentum-Entangled Photon Pairs (1997-now)". Retrieved 2016-09-19.
- ^ Cramer, John G. (14 August 2007). "The UW Nonlocal Quantum Communication Experiment" (slide presentation). UW Faculty Web Server: John G. Cramer's Home Page. Seattle, Washington, USA: University of Washington. Retrieved 19 September 2016.
The experiment has been in testing phases since mid-January.... The experiment is presently being rebuilt, using avalanche photodiodes as the primary detectors. It will continue this Fall.
I've proposed to add Gravitational wave to the list of vital astronomy articles. Please comment. Headbomb {talk / contribs / physics / books} 16:46, 23 September 2016 (UTC)
- Although I personally have a great interest in that subject, I do not think that its practical implementation has yet reached the point where it is vital that one know about it in order to understand astronomy. A handful of observations below the level of noise is not enough to say that it is providing essential information about celestial bodies which would not otherwise be available. JRSpriggs (talk) 23:16, 23 September 2016 (UTC)
Introduction to Einstein field equations article needs correction
The first paragraph of the subject introduction states that the EFE "equate" the Einstein tensor with the stress-energy tensor. Based on my reading of the "Mathematical form" section, this is inaccurate. If my understanding of that section is correct, the statement should be to the effect that the EFE "relate" the Einstein tensor, the metric tensor, and the stress-energy tensor. Similar difficulties manifest themselves in the second paragraph of the introduction.
In addition to those corrections, some clarification may be in order. The first paragraph describes the Einstein tensor as an expression of "local spacetime curvature." The second paragraph seems to describe the metric tensor as "the spacetime geometry." Either one of those descriptions is inaccurate or there is a subtle difference between "local spacetime curvature" and "the spacetime geometry" that needs to be mentioned to alleviate the reader's sense of confusion.
--Xphileprof (talk) 18:42, 27 September 2016 (UTC)
- @Xphileprof: perhaps "the spacetime geometry" is just another way to implicitly refer to the totality of "local spacetime curvature", in which case there is no problem. Anyway, Wikipedia is yours, so by all means, be wp:bold and feel free to wp:fixit. - DVdm (talk) 20:06, 28 September 2016 (UTC)