Talk:Spacetime/Archive 20

Testing mobile interface fix

It used to be that if, on a phone

1. you did not pre-expand the sections of this article,
2. then navigated via "Click here for a brief section summary" to an unexpanded section,
3. or navigated via "(click here to return to main)" to an unexpanded section,
4. and then used the back button "<" to attempt to return to where you were,
5. you would get hopelessly lost.

Please double-check on an Android that this misbehavior has been fixed. I have tested on an iPhone. If the misbehavior has not been fixed but persists, please revert my four 2 April 2018 edits between 03:47 to 03:52.

Prokaryotic Caspase Homolog (talk) 05:07, 2 April 2018 (UTC)

• I validated on an Android phone. I also tested using an online mobile phone simulator. The misbehavior described above has been fixed. Prokaryotic Caspase Homolog (talk) 11:11, 7 April 2018 (UTC)

Corresponding changes in the main body

I have repeatedly emphasized that (except for non-controversial definitions, etc.) unsourced statements in the lede must be expanded upon with sourced statements in the main body of the article. For that reason, I resisted introduction of any mention of flashes and moving trains in the lede. I do believe Purgy has a point, that without further explanation, the term "kinematics" is without much meaning to a naïve reader.

In 1905, Einstein introduced special relativity (even though without using the techniques of the spacetime formalism) in its modern understanding as a theory of space and time. While his results are mathematically equivalent to those of Lorentz and Poincaré, it was Einstein who showed that the Lorentz transformations are not the result of interactions between matter and aether, but rather concern the nature of space and time itself. He obtained all of his results by recognizing that the entire theory can be built upon two postulates: The principle of relativity and the principle of the constancy of light speed. 

Einstein performed his analyses in terms of kinematics (the study of moving bodies without reference to forces) rather than dynamics. His seminal work introducing the subject was filled with vivid imagery involving the exchange of light signals between clocks in motion, careful measurements of the lengths of moving rods, and other such examples.

In addition, Einstein in 1905 superseded previous attempts of an electromagnetic mass-energy relation ...

Prokaryotic Caspase Homolog (talk) 13:06, 7 April 2018 (UTC)

References

The section summary section represents a form of extended lead

The section summary section is a form of extended lead, and should conform to all guidelines established in MOS:LEADCITE. In this manual of style guideline, we read:

Because the lead will usually repeat information that is in the body, editors should balance the desire to avoid redundant citations in the lead with the desire to aid readers in locating sources for challengeable material.

As written, the section summary section has been careful not to introduce new material outside of what has been covered in the main text. If any of the material in the section summary were challengeable, then the guideline recommends inline citations even if it represented nothing more that a condensed rephrasing of main text statements. However, none of the material in the section summary section is of a controversial nature.

Therefore, my reading of MOS:LEADCITE is that it is perfectly acceptable for the section summary section to rely upon the main article for all of its sourcing.

Prokaryotic Caspase Homolog (talk) 22:21, 25 May 2018 (UTC)

Can't have a huge section sourced to the article it's self. This is basic stuff. Can't WP:BURDEN .--Moxy (talk) 04:02, 26 May 2018 (UTC)

As I see it, the two banners result from ignoring the intentions that these summaries pursue. Subsuming this pseudo-section under lead requires a certain stretch in meaning, unacceptable to those, who deny these variations. This text block is an effort to exploit more advanced possibilities for structure in electronic encyclopediae within stretched rules of WP. Denying these attempts, and literal application of the law in force result in nullifying the attempts. Certainly, some appreciate this, and the banners are a first step to delete this section, unwelcome to them. Purgy (talk) 08:21, 26 May 2018 (UTC)

• Content added needs to be sourced to references you have seen as per stick to the sources....not to Wikipedia text as it may be wrong and not reflect the given source..... as Wikipedia itself is not reliable as per WP:CIRCULAR "Content from a Wikipedia article is not considered reliable unless it is backed up by citing reliable sources. Confirm that these sources support the content, then use them directly." Plus you need to WP:PROVEIT "Any material lacking a reliable source directly supporting it may be removed and should not be restored without an inline citation to a reliable source"

• The Wikipedia:Manual of Style/Lead section applies to the opening of an article not sections....as we have a house style for articles see MOS:SECTIONORDER....this is to avoid sections consisting of synthesis of Wikipedia content not explicitly stated by the sources. We also source all sections after the lead so readers and researchers don't have to run around looking for sources that may or may not be present.

• Best use prose format as per WP:USEPROSE. "Prose is preferred in articles as prose allows the presentation of detail and clarification of context".

--Moxy (talk) 17:31, 26 May 2018 (UTC)

Recent changes in transverse Doppler effect

@Albert Gartinger: made some recent changes to the discussion of transverse Doppler effect. Since his native language does not appear to be English, as evident in this Quora contribution of his, I made a number of tweaks to correct awkwardness in his expression.

Overall, however, I do not believe that his contributions represent an improvement. In the original text, the distinction between scenarios (a) and (b) was clearly between (a) receiver at its geometrically closest approach to the source, versus (b) receiver seeing the source as being closest to it.

The current wording makes it seem as if the distinction is between (a) moving observer versus (b) moving source, which is of course absurd.

I would recommend that the text be reverted to what it was before his changes. The use of colors in his illustration to illustrate redshift and blueshift, however, is very nice, and should be adopted in a revision of the old figure. Prokaryotic Caspase Homolog (talk) 04:43, 26 September 2018 (UTC)

It seems that you wish to turn plain and simple things into confusing and quirky ones again. This has no perspective. Interpretations by "stationary" observer and "moving" observer are different, it is 100% evident. I have intentionally placed "moving inertial" and "rotating" observers into the same column.

You wish to hide under the carpet observer's own movement . You want to assert that the observer can only be at rest. You want to continue these stupid statements that one observer is always slower than the other. That is absurd. I will place links to this dialog on hundreds of other resources (including Quora) as an example of a blatant unwillingness to recognize the obvious facts. I will raise a scandal.

I will pay for a full - page ad in AJP, I can easily afford that, and will place everything there.

You can lead naive person astray, but anyone who has even a drop of brains, immediately understand what is what.

Just think what you have written: "the source .... observes the receiver as having a time-dilated clock". In order to deceive, you play with words, . Source simply shines, it observes nothing. It is the moving receiver, who "sees" that clock "at rest" relative to him ticks faster, than his own. Albert Gartinger (talk) 06:34, 26 September 2018 (UTC)

Please indent your talk page messages as outlined in wp:THREAD and wp:INDENT — See Help:Using talk pages. Hoping you don't mind, I have somewhat restructured your message and remove the section header.

@Prokaryotic Caspase Homolog: if you have a good textbook source for the original content—as you should have, and as I'm sure you do have—then feel free to restore it and put a pointer to the source in the text, so "discussions" like this are unneccessary and in fact impossible.

@Albert Gartinger: please note that Wikipedia is a place where people cooperate and where articles grow under wp:consensus. Please wp:assume good faith, as threats like the above tend to bring us nowhere. Your comments are very close to wp:personal attacks, which, by Wikipedia policy, are not tolerated here. If you have a reliable textbook source for your version, please bring it here, so a discussion can take place, based on sources. Thanks. - DVdm (talk) 07:08, 26 September 2018 (UTC)

@Prokaryotic Caspase Homolog: took it from the "reliable" book by Morin. It is shameful to mention or to copy - paste these misleading claims. I have already promised what I will do. I will post it at all physics forums, everywhere, I will send hundreds of emails. You will be laughed at. Albert Gartinger (talk) 07:27, 26 September 2018 (UTC)

Well, reverse changes. This will be perfect demonstration how Einstein's "relativity" keeps afloat. The case is EVIDENT. Do that, go ahead. I will devote all my free time to the fact that I will blow it all over the world. On the other hand, if you will not reverse the changes, I will post everywhere that the article contradicts itself. Albert Gartinger (talk) 07:45, 26 September 2018 (UTC)

Please indent your talk page messages as outlined in wp:THREAD and wp:INDENT — See Help:Using talk pages.

@Albert Gartinger: if you continue this, you will get blocked for wp:personal attacks. - DVdm (talk) 07:52, 26 September 2018 (UTC)

@Prokaryotic Caspase Homolog: Here it is: https://www.mathpages.com/home/kmath587/kmath587.htm, this is RELIABLE source. In that frame, where receiver and source move at the same but opposite velocities, there is no transverse Doppler effect at all, since their clock dilate at the same magnitude. It is written black on white. Why not to mention that? Albert Gartinger (talk) 08:02, 26 September 2018 (UTC)

FWIW, I personally think that Brown's mathpages (and his book) are indeed reliable, even if (both) self-published. For Wikipedia standards self-published work is usually not reliable—see wp:Identifying reliable sources#Questionable and self-published sources. Of course if we agree here that it is reliable, it can be used to support article content. The mathpages are indeed used elsewhere as a source, but adding a standard textbook source would do no harm. - DVdm (talk) 09:41, 26 September 2018 (UTC)

Scenarios (a) and (b) of the original text can—and should—be rewritten so that no misleading distinction is made between "moving" versus "stationary" source or receiver. The two are merely passing each other in uniform relative motion. The important distinction is between the two being geometrically at their closest approach to each other, versus the receiver "seeing" the source as closest. The current wording and illustration, which distinguish between moving observer versus moving source, is not good. Prokaryotic Caspase Homolog (talk) 12:04, 26 September 2018 (UTC)

There must be plenty of sources. Clearly the scenario should be rewritten along an agreed upon reliable source. Otherwise this discussion will not end. If there is no such source, we can safely —and must— delete the scenario per wp:nor. - DVdm (talk) 12:19, 26 September 2018 (UTC)

This section is somewhat oddball in that it makes no use of spacetime diagrams, whereas the rest of the special relativity section attempts, as much as possible, to adhere to a spacetime development of the topic as opposed to the kinematic development found in most textbooks. So the case could be made that this section should be deleted on that basis. Prokaryotic Caspase Homolog (talk) 12:32, 26 September 2018 (UTC)

No problem with me, but I'd delete it solely on the basis of wp:unsourced and, as a consequence, inappropriately discussed on talk page . - DVdm (talk) 12:42, 26 September 2018 (UTC)

Although self-published, I consider David Morin's book to be reliable, since it represents a revised and expanded version of the last four chapters of his conventionally published Introduction to Classical Mechanics, with Problems and Solutions (Cambridge University Press, 2008). David Morin is a Lecturer on Physics at Harvard University. "I chose to self-publish this book so that I could keep the cost low. The resulting eBook price of around $10...is less than a movie and a bag of popcorn, with the added bonus that the book lasts for more than two hours and has zero calories..." Give me a few days to get to the university library. There, I can look up his conventionally published textbook to see if that may be substituted as a reference. Prokaryotic Caspase Homolog (talk) 12:50, 26 September 2018 (UTC)

Agreed. I have the ebook versions of both the 2004 and the 2008 editions, the latter being the Cambridge University Press one, ISBN 978-0-511-37723-5. We can use that one for inline references. If we just follow this one and mention the pages in the book, there should be no problem with the wp:verifiability. - DVdm (talk) 17:42, 26 September 2018 (UTC)

Please note, that in &7 Theory of Doppler principle and aberration of Einstein's 1905 paper Einstein gives Doppler shift formula for moving observer.

https://www.fourmilab.ch/etexts/einstein/specrel/www/

So, my analysis and the diagram for moving observer is solely based on Einstein's 1905 paper. Self - published Morin has nothing to do with it. Einstein works in the frame of the source and for the special case cos\theta = 0 his formula reduces to nu'= \nu \gamma. Please also note that I have saved current version of the article in PDF and this talk page too. I am not sure that any reverts that can confuse the issue will benefit Wikipedia and your reputation as editors. Albert Gartinger (talk) 18:26, 26 September 2018 (UTC) Also: Feynman lectures, Relativistic effect in radiation, there are two different cases for moving observer and moving source.Albert Gartinger (talk) 18:46, 26 September 2018 (UTC)

Note that Morin's book (Morin, David (2008). Introduction to Classical Mechanics: With Problems and Solutions. Cambridge University Press. p. 541. ISBN 978-1-139-46837-4. Extract of page 541, transverse Doppler effect) is obviously not self-published. I think we can safely use and keep using it as a reliable source. - DVdm (talk) 18:55, 26 September 2018 (UTC)

Apparently, since I am accessing Google Books from the U.S., I am not allowed to view the same selection of pages that you are allowed to view. My wife has given me permission to visit the library after work. As Darth Vader might have said in Return of the Jedi, "I want to view the book with my own eyes." Prokaryotic Caspase Homolog (talk) 19:02, 26 September 2018 (UTC)

What about Einstein or Feynman? Are they reliable sources?Albert Gartinger (talk) 19:11, 26 September 2018 (UTC)

Einstein is a primary source, and Wikipedia strongly discourages editors from using their own interpretations of primary sources. Whenever possible, reliable secondary sources are recommended.

Your critiques have been helpful, since they have highlighted some issues with the original text. Also, the manner in which you used color and distinguished between apparent and actual positions in your illustration are also enlightening. We are not ignoring your concerns. Prokaryotic Caspase Homolog (talk) 19:30, 26 September 2018 (UTC)

I am afraid to say, but it is not I who gives "my own interpretation" of the celebrated Einstein's 1905 paper. It is someone else writes confusing explanations of very simple things. Einstein CLEARLY speaks about moving observer in his paper and gives exact formula, which is simple enough even for elementary school children. It a bit interferes with some other claims, but it is not my problem. Einstein synchronization in every frame is a problem, equality of one - way speed of light c in all frames is a problem or half truth at least.Albert Gartinger (talk) 19:39, 26 September 2018 (UTC)

Please note, that the article speaks about purely transverse Doppler effect. An observer can give double explanation towards the nature of the effect.

1. I move in the frame of the source and the source appears displaced due to aberration and blueshifted due to dilation of my own clock. This is transverse effect.

2. The source moves in my frame and displaced due to light - time correction and blueshifted due to presence of longitudinal component.

Morin confuses everything. I believe he plays a fool. Does he really not understand, that moving observer sees that clock at rest runs faster. I think that he intentionally writes confusing explanation so as to lead readers astray.

Please note that rotating observer also sees that the source in the center displaced and blueshifted. However, rotating observer can think about himself only in terms of his own motion and cannot ascribe state of relative motion to the source. If purely inertial observer momentarily coincides with rotating one, he will see blueshift of frequency at the same magnitude.

The same way double explanation can be given towards redshift as seen by inertial observer. We cannot say that the observer cannot move and aberration does not exists from the point of view of moving observer. We know that since Bradley. Aberration can be only explained by our own motion Albert Gartinger (talk) 20:07, 26 September 2018 (UTC)

Except for trivial changes in equation numbering and figure numbering, I see no difference between the discussion of transverse Doppler effect in Special Relativity: For the Enthusiastic Beginner versus the treatment in Introduction to Classical Mechanics. There is therefore no issue with replacing the references in the article with those in Morin's conventionally published textbook, which obviously has no issues with wp:verifiability. Prokaryotic Caspase Homolog (talk) 02:59, 27 September 2018 (UTC)

I reverted and changed the references to Introduction to Classical Mechanics. I also revised the language so as to reduce any inadvertent implication that in scenarios (a) and (b), one object should be considered as moving while the other is stationary, instead stressing the frame in which the scenario is best analyzed. I downloaded the figure, and I will see how successful I can be in incorporating the nice features that you had in your version of the figure to illustrate redshift vs blueshift, and observed vs actual positions. Prokaryotic Caspase Homolog (talk) 05:22, 27 September 2018 (UTC)

Transverse Doppler effect: As discussed in Talk, revising language that would appear to imply that one or another of the source/receiver is moving while the other is stationary It is so much stupid motivation, so there is nothing to talk with you about. But, I will arrange some negative publicity, particularly among youth. The case is very clear, so it sounds very silly at least to make claims that the source can move but the receiver can’t. It is necessary to rid science of people like you. Albert Gartinger (talk) 06:00, 27 September 2018 (UTC)

One chooses the frame in which the analysis is most convenient. In scenario (a), analysis from a frame in which the receiver is stationary is inconvenient, not wrong. Rather, the only reason to choose to do the analysis from the frame of the source is that it leads to easier math. In scenario (b), one could certainly do the analysis from the frame of the source, but it is significantly harder to do it that way than doing it from the frame of the receiver. I do not understand the point that you are trying to make. It may be a language barrier. You appear to be claiming that I insist that the source can move but the receiver can't. If that is what you are claiming, then you are misunderstanding my language. Prokaryotic Caspase Homolog (talk) 07:50, 27 September 2018 (UTC)