Talk:Superluminal motion

Diagram
Can someone post a diagram. This is one of those things that is very easily explained on a blackboard, but hard to explain with words. Roadrunner 20:24, 25 Feb 2004 (UTC)

First the blob is moviong towards me and then the blob in on a path perpendicular to me. This doesn't seem to match another explanation I found but I don't fee comfortable changing it.

More explanation needed
This result is not that intuitive (if the object is moving mostly towards you, the tangential velocity cannot be very high, and it is not obvious that the time interval decreases faster), so I think a quantitive treatment is necessary, something like the explanation here. I'll add that as a "See also" link before someone gets around to do a good explanation here. R6144 09:54, 23 August 2005 (UTC)

How to achieve real superluminal velocity of mass particles see:

http://www.petar-bosnic-petrus.com/science-articles/ conical-and-paraboloidal-superluminal-particle-accelerators/


 * I agree. From current explanation it is not clear that there would be any apparent superluminal velocity involved. In fact, as usual with physics wikipedia pages, the explanation is dim and dense.Crusty007 (talk) 20:37, 8 March 2009 (UTC)

See http://www.iop.org/EJ/article/0031-9120/32/1/016/pe7103.pdf?request-id=536d1dcd-4580-4a47-b434-93dd3b9a89bd for another explanation, i find it clearer, and it includes quantitative analysis —Preceding unsigned comment added by 131.111.1.66 (talk) 13:59, 8 April 2009 (UTC)

The explanation relating to signal velocity is far more logical, at last. Nothing moves faster than C, but the information; 'change of position' can of course give the impression of something in a different inertial frame moving faster or slower. Interesting implications too.Nimsdixon (talk) —Preceding undated comment added 23:46, 10 February 2010 (UTC).

Dubious sections?
If the ideas proposed in the section "Laser ranging" are based on a mistaken calculation on the part of Gezari, as explained in Franklin's paper, rather than an actual observation, it seems a needlessly distracting detour.


 * Agree. I just read his paper at http://arxiv.org/ftp/arxiv/papers/0912/0912.3934.pdf and I'm thinking, what is this guy doing at NASA for so many years? It'd be good if some of his peers can review this crap so that Wikipedia can get rid of this section.-Dhatsavan (talk) 12:05, 17 December 2010 (UTC)

The paper of Gezari was recently updated. (Bgeelhoed (talk) 15:38, 31 August 2010 (UTC))


 * But it remains mistaken, and it does not address the criticisms in the Franklin paper. The Gezari paper and the Franklin rebuttal should both be removed as wastes of space, or regrouped under a new section heading, "Mistaken claims of Superluminal Motion", which could include other examples, too.  — Preceding unsigned comment added by 128.112.25.51 (talk) 07:19, 3 August 2011 (UTC)

The section "Messier 87 etc. Gas Jets" appears to be based on a non-standard theory (the Wikipedia article on this theory is disputed as original research), but that isn't made clear in this article. Dependent Variable (talk) 00:49, 5 April 2010 (UTC)

Error in diagram
The diagram shows OB=OC=D_L. If so, then the angle OCB cannot be a right angle. There must consequently also be an error in the derivation. — Preceding unsigned comment added by 80.152.247.201 (talk) 07:24, 19 October 2011 (UTC)

Technically, you're right. In practical terms, however, the distance DL is so large that angle ø is approximately zero, so the derivation is correct to a good approximation. For ø = 1 arc-minute, the two distances marked DL in the diagram differ by a factor of about 4E-08.

132.3.33.68 (talk) 13:59, 10 February 2012 (UTC) I think it is worth mentioning this in the derivation. It's good practice to always state your assumptions (especially when they're accompanied by a diagram that appears to contradict them). — Preceding unsigned comment added by 111.69.239.65 (talk) 10:15, 10 September 2013 (UTC)

Superluminal or not?
The article equivovates on whether superluminal motion is observed or not. Are some jets truly superluminal? J Mark Morris (talk) 22:40, 6 February 2019 (UTC)


 * I'm not sure how you say that it equivocates: "is the apparently faster-than-light motion" in the lede, and "jets traveling very near the speed of light" in the first main paragraph. None of them are truly superluminal, they're all due to projection effects. - Parejkoj (talk) 17:33, 7 February 2019 (UTC)


 * In the contrary evidence section and the history section there are several mentions of superluminal events that are not explained away.J Mark Morris (talk) 23:18, 9 February 2019 (UTC)

Original research?
I've added the "Original research" tag because the section entitled "Derivation of the apparent velocity" is entirely unsourced. It looks like an impressive piece of work, but given the lack of any cites, I wonder if it is original research. Some citations are necessary to support it, in my opinion. WP:ORIGINAL Mr Serjeant Buzfuz (talk) 23:04, 4 August 2023 (UTC)