Talk:World line

message: Would you please comment on the new "light cone" image we have prepared. The intention was to imply the correct scale of space-time relative to the observer. Interstellar light-years vs years scales seemed appropriate. Thoughts? Dhatfield (talk) 11:55, 27 June 2008 (UTC)
thread_title:  New image 

message: Considering that World lines are essentially a physics concept, the importance placed on the literature section feels out of place for the article. Reading the introduction, I do a double take at the sentence "in general usage, a world line is the sequential path of personal human events" wait... what? That's not general usage, but just an interpretation of how it applies to people. The section headings "Usage in Physics" along with "World line in Literature" suggest that world line is a general concept that takes specific and different meanings in the context of literature vs. physics. This isn't really the case.  — Preceding unsigned comment added by 142.244.176.240 (talk) 00:49, 20 November 2013 (UTC)
thread_title:  Literary importance out of place 

message: When time is treated as a fourth spatial dimension, there is no chronological time. Thus world lines are the static, eternal path traced by an object, but it is incoherent to describe the object as "travelling" through Minkowski space. With no chronological time there is no change, no motion. If we speak of motion through the fourth dimension, then we must also answer absurd questions like  "at what speed is the object moving through the fourth dimension?" ie "What is its change in time with respect to time?"  — Preceding unsigned comment added by 1.72.2.98 (talk) 06:27, 12 March 2015 (UTC)
replies: text: I've reworded the first sentence to fix this. —Quondum 18:19, 12 March 2015 (UTC)
thread_title:  Use of the word "travel" 

message: can we get a mod or someone in here to settle this? i don't think this company is worthy of piggybacking off minkowski's background.
i don't think when people google worldline they're looking for the company. they're looking for the mathematical construct.
paging user:mindmatrix, help pls? ty  — Preceding unsigned comment added by 174.3.213.121 (talk) 01:29, 27 May 2015 (UTC)
replies: text: I'm in agreement here: remove the hatnote.  There must be many instances of a word being used as a company name, and to provide a hatnote like this for the very occasional person who might seek it would clutter WP with adverts for companies.  —Quondum 02:40, 27 May 2015 (UTC)
thread_title:  disambiguation for 'wordline' company at top of page 

message: The image under the aforementioned section is somewhat misleading.
https://upload.wikimedia.org/wikipedia/commons/d/d8/Worldlines1.jpg
The "faster object" and "very fast object" lines don't reflect reality. As far as I'm aware, the overwhelming convention in spacetime diagrams is that the line y=x represents a light-speed trajectory. Thus, it appears that "faster object" is travelling about the speed of light, and "very fast object" appears to be traveling much faster than the speed of light.
A more conventional image would have two or three example lines whose slope is greater than one, and an additional one or two lines showing a light-speed trajectory (the light cone from the origin). An illustrative example could even have a fifth line whose slope is less than one, and point out that such a world line involves faster than light travel, and is thus impossible under conventional understanding.  24.107.185.147 (talk) 03:43, 9 July 2015 (UTC)
replies: text: Agreed, in this context it would be more conventional and less confusing to have all the lines above 45°.  —Quondum 05:20, 9 July 2015 (UTC)
replies: text: The same criticism applies to Richard Haskell's essay in Ext Lks:  in depth text on world lines and special relativity. Though a thoughtful essay, it does not appear to be a reliable source for this article.Rgdboer (talk) 23:35, 10 July 2015 (UTC)
thread_title:  Misleading image under "Trivial examples of spacetime curves" 

message: In the Usage In Physics section of the World line page, there is a statement saying that "The mathematical term for spacetime is a four-dimensional manifold." This needs to be corrected slightly as it makes it sound like spacetime and manifolds have the equivalent definition. Perhaps it should say instead that "In mathematics, spacetime is an example of a four-dimensional manifold." Sammysimplex (talk) 02:05, 6 November 2015 (UTC)
thread_title:  Oddly worded statement about manifolds