Talk:Geodesic (general relativity)

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[edit] Article layout requests

Hi User:AugPi, good job on the article. I have several requests, though:

• Can you please not use boxed equations? This is a kind of house-style used in the math articles; see Wikipedia:How to write a Wikipedia article on Mathematics. The discussion about boxes around equations comes up every now and then, and the boxes tend to loose. linas 00:53, 2 August 2005 (UTC)

I have removed them. Boxes which run right up to the right margin don't look too good, so I had cut down on the length of the boxes to center the equations inside them. I did this in Safari, then when I logged on with Netscape the boxes became shorter than the equations, so boxes can be problematic.

Thanks! linas 00:29, 4 August 2005 (UTC)

• Can you please consider moving much/most of the long derivation off to a subpage called Proofs for the article Geodesic (general relativity), as per the discussion in Wikipedia:WikiProject Mathematics/Proofs ? See, for example, Cardioid proofs and Laplace_operator/Proofs. The goal here was to provide the "rigor" that is desired, without actually cluttering up the article. linas 00:53, 2 August 2005 (UTC)

I moved the calculations to Geodesic (general relativity)/Proofs. Incidentally, I didn't know that I could create article titles with slashes: that could come in handy. —AugPi 05:23, 3 August 2005 (UTC).

They're called "sub-pages", and actually, according to WP policy, one is not supposed to use sub-pages for articles. (its OK to use them on personal pages, talk pages, etc.) Appearently, subpages tended to get misused, which is why there's a policy against them. I've asked for special dispensation, that an exception be made for the case of these types of proof pages. Not clear what the final ruling will be, if any. (the alternative is to have a strict naming convention "XXX article proofs" or something like that.) linas 00:29, 4 August 2005 (UTC)

[edit] Really maximum length?

There is a sentence: A geodesic between two events could also be described as the curve joining those two events which has the maximum possible length. From other sources I've heard, that the geodesic is actually a minimum possible length.

(The maximum-length curve goes arround the whole universe before getting to the target...)

Could you, please, verify that?

In GR, there is an "invarient interval" which for timelike paths is the proper time experienced as one travels along that path. This proper time acts as a length in relativity and is maximized for inertial motion (which is also geodesic motion in relativity). So it is correct that geodesics in realtivity maximize the length between events, while purely spatial geodesics minimize the length between positions. (For an example of how acceleration decreases the elapsed peoper time between events, see the twin paradox article.) --EMS | Talk 22:50, 24 October 2006 (UTC)

As noted in the leader, geodesics can be spacelike or timelike or null. Timelike geodesics are particularly interesting because they are the paths that free massive particles follow, but they are not the only geodesics. Also, I think it's good policy to try to incorporate the answers to legitimate questions (like this one) into the text of the article itself. I'm trying to do this, and brush up a few other points. --MOBle 03:44, 4 December 2006 (UTC)