Misplaced Pages

Talk:Special relativity

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.

This is an old revision of this page, as edited by JohnBlackburne (talk | contribs) at 09:44, 29 October 2018 (→I need help here: reply). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Revision as of 09:44, 29 October 2018 by JohnBlackburne (talk | contribs) (→I need help here: reply)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)

Template:Vital article

Former good articleSpecial relativity was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
Article milestones
DateProcessResult
December 16, 2004Featured article candidateNot promoted
January 1, 2005Good article nomineeListed
February 12, 2006Featured article candidateNot promoted
October 30, 2006Good article reassessmentKept
August 26, 2009Good article reassessmentDelisted
Current status: Delisted good article
This article has not yet been rated on Misplaced Pages's content assessment scale.
It is of interest to the following WikiProjects:
Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.
WikiProject iconAstronomy Top‑importance
WikiProject iconThis article is within the scope of WikiProject Astronomy, which collaborates on articles related to Astronomy on Misplaced Pages.AstronomyWikipedia:WikiProject AstronomyTemplate:WikiProject AstronomyAstronomy
TopThis article has been rated as Top-importance on the project's importance scale.
Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.
WikiProject iconTime Top‑importance
WikiProject iconThis article is within the scope of WikiProject Time, a collaborative effort to improve the coverage of Time on Misplaced Pages. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.TimeWikipedia:WikiProject TimeTemplate:WikiProject TimeTime
TopThis article has been rated as Top-importance on the project's importance scale.
Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.
WikiProject iconPhysics: Relativity Top‑importance
WikiProject iconThis article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Misplaced Pages. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.PhysicsWikipedia:WikiProject PhysicsTemplate:WikiProject Physicsphysics
TopThis article has been rated as Top-importance on the project's importance scale.
This article is supported by the relativity task force.
Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.
WikiProject iconMathematics Top‑priority
WikiProject iconThis article is within the scope of WikiProject Mathematics, a collaborative effort to improve the coverage of mathematics on Misplaced Pages. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.MathematicsWikipedia:WikiProject MathematicsTemplate:WikiProject Mathematicsmathematics
TopThis article has been rated as Top-priority on the project's priority scale.
Got a question? Don't ask here!

Template:WP1.0


Archives

1, 2, 3, 4, 5, 6, 7, 8, 9, 10
11, 12, 13, 14, 15, 16, 17, 18, 19, 20
21, 22, 23


This page has archives. Sections older than 90 days may be automatically archived by Lowercase sigmabot III when more than 5 sections are present.

This is the talk page for discussing improvements to the Special relativity article.
This is not a forum for general discussion of the article's subject.
Article policies
Find sources: Google (books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL
Archives: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23Auto-archiving period: 3 months 

Edit request: lede is factually wrong.

The lead contains the following false claim:"As of today, special relativity is the most accurate model of motion at any speed." It should be obvious that for macroscopic motion (that is, where.when quantum mechanics isn't needed) that GENERAL relativity is the "most accurate model of motion" (at all possible speeds).71.29.172.222 (talk) 15:39, 3 July 2016 (UTC)

 Not done. Special relativity can handle all possible speeds—see the article: "The theory is "special" in that it only applies in the special case where the curvature of spacetime due to gravity is negligible. In order to include gravity, Einstein formulated general relativity in 1915. Special relativity, contrary to some outdated descriptions, is capable of handling accelerated frames of reference."

References

  1. Koks, Don (2006). Explorations in Mathematical Physics: The Concepts Behind an Elegant Language (illustrated ed.). Springer Science & Business Media. p. 234. ISBN 978-0-387-32793-8. Extract of page 234
  2. Steane, Andrew M. (2012). Relativity Made Relatively Easy (illustrated ed.). OUP Oxford. p. 226. ISBN 978-0-19-966286-9. Extract of page 226
- DVdm (talk) 18:07, 3 July 2016 (UTC)
  • I agree that it is factually wrong. For example, the motion of a very heavy body in the neighbourhood of another very heavy body is not correctly predicted by special relativity, whereas it is correctly predicted by general relativity. An example would be two neutron stars. Hence special relativity is less accurate than general relativity in this case, meaning that special relativity is not the most accurate model of motion. The text could be changed to "special relativity is the most accurate model of motion at any speed when gravitational effects are negligible". I don't think the statement by DVdm addresses this issue. Ian Hinder (talk) 12:42, 20 May 2017 (UTC)
No problem with that: . My objection was to the wording of the request. - DVdm (talk) 13:15, 20 May 2017 (UTC)

Wrong answer in the section "How far can one travel from the Earth?"?

I got v ≈ 0.72 c {\displaystyle v\approx 0.72c} , not v = 0.77 c {\displaystyle v=0.77c} , given this equation and these variables v ( t ) = a t 1 + a 2 t 2 c 2 , a = 9.81 m / s 2 , t = 3.1536 10 7 s {\displaystyle v(t)={\frac {at}{\sqrt {1+{\frac {a^{2}t^{2}}{c^{2}}}}}},\quad a=9.81\,\mathrm {m} /\mathrm {s} ^{2},\quad t=3.1536\,10^{7}\,\mathrm {s} } . Am I missing something? Anyone else got the same result?

Ximalas (talk) 20:40, 21 February 2018 (UTC)

Yep. Feel free to change. This kind of thing should have a good source. - DVdm (talk) 21:11, 21 February 2018 (UTC)

Thought experiments

In his popular and semi-popular writings, Einstein was well-known for illustrating basic concepts of relativity with the aid of thought experiments.

Am I simply missing it, or does there not exist an article in Misplaced Pages devoted to "Special relativity thought experiments"?

Would creation of such an article be desirable? Or would such an article violate wp:NOTTEXTBOOK?

Prokaryotic Caspase Homolog (talk) 03:24, 5 April 2018 (UTC)

I think that it would be a good article to have, if it is framed as an article about the history of relativity and limited to sourced thought experiments devised by Einstein himself. JRSpriggs (talk) 04:24, 5 April 2018 (UTC)
Definitely it needs to be a sourced article. If we wish to make it an historical article strictly about Einstein's unique approach to conceptualizing complex scientific ideas, then the article name could be "Einstein's thought experiments", that would describe the ones that he devised not just for special relativity, but also ones that he devised for general relativity and for quantum mechanics. Prokaryotic Caspase Homolog (talk) 10:11, 5 April 2018 (UTC)
@JRSpriggs: I have created Einstein's thought experiments. I hope you find it decent. Prokaryotic Caspase Homolog (talk) 17:14, 28 April 2018 (UTC)
Yes, thank you. JRSpriggs (talk) 01:39, 29 April 2018 (UTC)

Measurement versus visual appearance

Triggered by recent edits ... While I have no (perceived) problem in the original, probably terse version of identifying the "measured shape" of an object as a collection of 3d-space-coordinates, obtained from a section of spacetime coordinates, and appropriately associated to corresponding object-inherent coordinates, revealing the length contraction in the direction of the velocity, I am unsure about the term "snapshot" in the current version. I think "snapshot" is "taking a picture", and induces inherently propagation of light, which is carefully excluded in "observing", i.e. taking spacetime coordinates.

I must admit that the notion of "visual appearance" is a bit bewildering to me in both versions. I think this is now about taking a "snapshot", which involves a central projection, including dependencies on distance between the object and the observer, the direction of the velocity, and what not.

I think that the presented material is excellent, but the presentation is not fully rigorous and sufficiently explicative, and I am unsure, whether the edits constitute an improvement. 12:29, 10 September 2018 (UTC)

Can you suggest a better wording? Now that you bring it up, I can see the problem that you might have with the word "snapshot" as a means of describing the "measured shape" of an object. Prokaryotic Caspase Homolog (talk) 02:14, 12 September 2018 (UTC)
I am sorry, but my reservations, and only sometimes direct suggestions for marginal improvements, are all I can provide. I am an intuition-less non-expert in STR, heavily suffering from the total collapse of the concept of rigid body in STR already in 1 dimension (rockets with string). Additionally, I disagree with certain adhered to concepts (necessity of talking about moving observers vs. light sources) claiming to be based on Einstein, and I do not feel adequately versed in the use of this non-native tongue, to express such delicate matters. Purgy (talk) 08:02, 12 September 2018 (UTC)
Hmmm... You bring up a variety of issues unrelated to your original concern. Born rigidity and Bell's spaceship paradox are not covered in the article as presently written, but one could argue that they need to be covered. One could also argue that coverage of those topics would represent unnecessary digressions, given the article's other deficiencies. The collective authorship paradigm that Misplaced Pages follows, while very good for developing articles in history, biography, etc. has not proven itself very well adapted to the development of technical articles like special relativity. In common with most other technical articles, the current article is a hodgepodge of parts with widely differing levels of difficulty. It needs a thorough overhaul by a person with a clear vision of how the article should be structured and what the target audience is supposed to be.
However, giving this article a thorough overhaul is beyond my competency. I can only focus on the little bits and pieces that I myself have added. The best that I can promise is that I'll continue to think about the points that you raised. Maybe somebody else will find a better wording. Prokaryotic Caspase Homolog (talk) 23:39, 12 September 2018 (UTC)
I really had no intention to bring up these topics as issues of this article (in need of covering), but only as prominent in causing me troubles in developing a good intuition about STR. I feel quite similar to the description of your last paragraph, just additionally handicapped by the necessity to use a non-native language.
Triggered by your remarks, I want to mention a thorough attempt -not too long ago- to deal with this article in the perspective you mentioned, which seems to have failed the target, but certainly has brought about significant improvements. BTW, I strongly object to the collective authorship paradigm being any good for questionable articles in history or biography. All the best, Purgy (talk) 07:13, 13 September 2018 (UTC)
This article? The last really major revamping that I recollect was the decision in mid-2015 to delete Introduction to special relativity as being an even worse hodgepodge than the main article. Prokaryotic Caspase Homolog (talk) 07:52, 14 September 2018 (UTC)
I am deeply concerned by me sloppily mixing up this article with Spacetime, which encountered heavy efforts of targeted improvement in 2017. My attention here was by far too focused on the "snapshooting" of "spacetime vectors", i.e., just on the local changes, being related to STR. Pardon! Purgy (talk) 09:36, 14 September 2018 (UTC)
The strength (and weakness!) of Spacetime as currently written was the principal editor's determination to adhere, as much as possible, to a purely geometric approach to presenting the material. There are neither trains nor lightning bolts in Spacetime. For the most part, the geometric demonstrations are logically presented, but by their very nature, the demonstrations are somewhat divorced from intuitive understanding. Most people, including myself, are rather more comfortable with a kinematic approach, i.e. with railway cars and spaceships. The problem is, how to add this introductory material? Most "Introduction to" articles get only a few percent of the readership of their associated main articles. Instead of trying to resurrect Introduction to special relativity (which needs to stay dead), I wonder if such material could be added as an extended introductory section to the current article? Against this idea would be the following objections:
1) Such material could very easily violate wp:NOTTEXTBOOK.
2) Such an introductory section could easily double the size of this article.
3) A featured wikibook exists on Special Relativity which has the merits of being principally authored by a single knowledgeable editor. It has a consistent presentation and relatively clear focus, and as a wikibook, it was allowed to take on textbook aspects. Despite this, I'm not very happy with it. Could somebody like myself do any better? Absolutely not.
Thoughts? Prokaryotic Caspase Homolog (talk) 15:17, 14 September 2018 (UTC)
... thinking ... Purgy (talk) 08:35, 15 September 2018 (UTC)

I take back part of what I said about the wikibook. I'm very unhappy with it. If you're going to write a textbook on special relativity, you need problems with solutions, or at least lots of example scenarios. Prokaryotic Caspase Homolog (talk) 11:10, 15 September 2018 (UTC)

To start with the result of my thinking: I have none. I agree on your verdict the wikibook not making me happy, I do not cling to the WP:NOTTEXTBOOK beyond not allowing for collections(!) of examples (paradigmata are a core necessity in WP! imho), yes, the danger of doubling the length is dangling, and finally, given my engagement and eruditeness on this matter, I am convinced I could not do half as good as you.
As an aside, I am very skeptical about the usual intuition on kinetics. All this rubbish about "moving observers" stems imho from "intuitively" "observing" TWO reference frames, thereby silently introducing a third frame, leaving the uninitiated confused.
Sorry, I think the best I can do, is commenting from the off sometimes. Please, do never assume any malevolence from my side. Purgy (talk) 07:36, 18 September 2018 (UTC)

Rearranging the sections, and now I'm stuck

I've been rearranging the sections of this article so as to put them into a more rational order, and now I'm stuck.

There are a variety of approaches to teaching relativity:

  • The dominant approach found in most college textbooks is begin with the "two postulates" (almost always starting with a stronger, less intuitive form of the second postulate than that adopted by Einstein in his 1905 paper) and to proceed through relativity of simultaneity, time dilation, length contraction etc. to the Lorentz transformations. While traditional, this principle-based approach has many issues. As Miller has noted, "Teaching STR that way is especially problematic because, unlike the case of classical thermodynamics which is also taught as a principle theory, the two postulates or principles in the case of STR are strongly counterintuitive when taken together."
  • Several textbooks begin with Minkowski spacetime as the central focus, often approaching Minkowski spacetime through constructive arguments. This, for instance, is the approach adopted by Taylor & Wheeler's Spacetime Physics. The article Spacetime attempts consistently to follow this approach, how successfully, I'm not sure.
  • Some authors advocate beginning with the Lorentz transformations as the first principle. I know of no introductory college textbook that teaches special relativity this way.

This article starts off as if it were following a two-postulates presentation, and then suddenly switches over to presenting the Lorentz transformations as the first principle, from which everything else derives.

How should I go from here? Any suggestions? Prokaryotic Caspase Homolog (talk) 08:53, 28 October 2018 (UTC)

I think that I've managed a kludgy fix by adding some transitional commentary about different approaches to presenting special relativity. Prokaryotic Caspase Homolog (talk) 10:00, 28 October 2018 (UTC)
I personally am not happy with basing special relativity on the single postulate of universal Lorentz covariance, but that's the way the article appears to have been written. Prokaryotic Caspase Homolog (talk) 15:36, 28 October 2018 (UTC)

I need help here

Does this section really provide a comprehensible explanation of why FTL is impossible? All it does is state that "one can show" that causal paradoxes can be constructed. Prokaryotic Caspase Homolog (talk) 03:24, 29 October 2018 (UTC)

It makes sense to me. It explains how FTL travel would violate causality. There’s no proof of causality but it’s intuitively very appealing as without causality paradoxes arise, so is widely accepted as being true. And if you accept causality then FTL travel must be impossible.--JohnBlackburnedeeds 03:47, 29 October 2018 (UTC)
I restored the section, but I still don't like it. At the very least, it needs a second Minkowski diagram showing how, through the exchange of FTL signals, one can generate a causality-violating scenario. As currently written, it demands an act of faith on the part of the reader. I suppose I could draw the necessary diagram and modify the text to work with the new figure. I don't see a ready-made figure on Commons that will do. Prokaryotic Caspase Homolog (talk) 04:57, 29 October 2018 (UTC)
It’s alright to me. It’s the sort of thing that’s hard to draw as it quickly gets cluttered, but if you’ve looked at enough such diagrams you can visualise it in your head. Or follow the logic of the text which does not really depend on the diagram except to initially establish the relationship between A, B and C.
I’m removing the text too now it’s back in the article; it’s still in the page history if there’s any need to refer to it.--JohnBlackburnedeeds 09:44, 29 October 2018 (UTC)
Categories: