Talk:World line

Early notes
--Sir48 9 July 2005 12:13 (UTC)What is this ?
 * It's user:Fwappler. See also Duration. Fwappler, please explain these things you are adding! Wikipedia is a general encyclopedia, not a scientific text. That doesn't mean anything must be dumbed down, but articles need an introduction that establishes CONTEXT and gives an overview -- Tarquin 10:54 Jan 5, 2003 (UTC)

I known I found this article trying to understand duration.

As for the above:


 * I'm sorry, the notion of Worldline which I've added doesn't readily admit any explanation besides those stated already, and as (at least partially) provided through their Links.
 * Set and Observational content are about as plain as I know to put it.


 * If this were not the principal notion of Worldline which We like to see, then my addition may constitute merely the aspect of Worldline:Scientific text. The article which links to this page might be similarly parcelt [parceled(?) - Patrick] . I surely don't wish to extend my reach beyond my grasp. Fortunately We seem to agree that Wikipedia is not a general encyclopedia to the exclusion of scientific text.

Best regards,  Frank W ~@) R,			Jan. 5, 20:57 PST.

Fwappler, something in the style of http://library.thinkquest.org/27930/worldlines.htm (which you've linked to) is required, at least for the introduction. -- Tarquin 09:32 Jan 6, 2003 (UTC)

I could not understand the content as it was and I have replaced the item with an entirely new text. Please add the old text again, but try to place it in a better context, starting e.g. with In philosophy a wordline is ... Jheise 18:00 Jan 6 2004

Why does this article in the text and the thumb-text of the illustration talk about the earth's orbit as (almost) a circle? The right expression "an ellipse" should be well known. --Sir48 9 July 2005 12:13 (UTC)

I changed the word 'singular' to unique in the first sentence. Worldlines are continuous and smooth most places. 'Singular' might be confused with a discontinuity or discontinuous derivative. -r

New image
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)

Time direction flow?
"Time flows from The Past to Now." That may not always be true, possibly not even in the classical macro realm. There are non-classical physical experiments which undeniably exhibit results where effect precedes cause, and experimental results in classical frames where the results may possibly be explained by virtue of positing "reversal" of time. The problem is human bias in that our brains interpret cause and effect classically when in relativistic terms there is no privileged frame of reference, even for time.

My physics classes are decades obsolete and far in the past :) however I also dimly recall a French physicist who mathematically demonstrated a theoretical basis for supposing that there is only one electron extant in the whole of space which is manifest as a superposition-like spread over the dimension we consider to be “time.” His work suggested a classical explanation of action-at-a-distance in the context that quantum entanglement was the result of there being only one electron in the whole of the Universe yet manifest spread out over time.

We're also seeing time reversal effects in nano circuitry which hold the potential to allow macro benefits in electronics and spintronics. Imagine memory storage densities in magnetic particles laid down on a gallinium substrate that take advantage of storing minute magnetic fields in the past, much, much longer than a Planck time or even longer than a chronon. :) One could even read data long before it was written. :) Damotclese (talk) 18:55, 8 December 2011 (UTC)


 * I think there is a fundamental problem with this page in that the heading says "This article is about a concept used in physics and literature." but, other than a few references to "World lines in literature", it is entirely about the usage in physics. In that context, the majority seems to have been well written by someone who understands the subject but there are significant parts that are badly flawed or complete rubbish. (For example "pendulum clock floating in space" wouldn't swing because a pendulum clock relies on gravity for its operation.) The statement "Time flows from The Past to Now." is not part of any scientific formualtion I know of and is incompatible with the "block universe" model which is probably the most prevalent philosophical interpretation of relativity. However, such interpretations aren't really relevant to an article explaining worldlines though a link to alternative philosophies of time could be helpful. I won't have time to fix this myself in the near future but it badly needs to be corrected.
 * George Dishman (talk) 19:56, 28 January 2012 (UTC)

Literary importance out of place
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)

Use of the word "travel"
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)


 * I've reworded the first sentence to fix this. —Quondum 18:19, 12 March 2015 (UTC)

disambiguation for 'wordline' company at top of page
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)


 * 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)

Misleading image under "Trivial examples of spacetime curves"
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)


 * 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)
 * 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)

Oddly worded statement about manifolds
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)