Talk:Transwiki:Special relativity for beginners
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[edit] en:Special relativity for beginners authors and history
- 2005-11-17 16:43:17 User:Natalinasmpf (vfd)
- 2005-11-04 16:52:01 User:Loxley m (franz taurinus)
- 2005-10-12 22:59:46 User:Haon (→See also - fixed link)
- 2005-10-12 22:54:40 User:Haon m (edited for clarity)
- 2005-09-29 02:01:23 User:129.24.95.218
- 2005-08-27 11:50:50 User:130.237.212.204
- 2005-08-19 14:29:44 User:Elijah m (added units to conversion constant ''c'')
- 2005-08-09 13:50:34 User:Perspicacious (→External links)
- 2005-08-09 13:50:01 User:Perspicacious (→External links)
- 2005-08-07 19:30:09 User:216.51.101.61
- 2005-08-05 19:43:34 User:24.0.118.17
- 2005-08-05 09:33:31 User:Loxley
- 2005-08-04 18:41:19 User:201.11.150.77
- 2005-08-02 12:59:56 User:Garo m
- 2005-07-27 13:03:45 User:207.173.67.219 (→External links)
- 2005-07-27 08:56:46 User:Loxley (→Caveats and Warnings)
- 2005-07-23 14:10:26 User:AdamJacobMuller m (alink)
- 2005-07-23 13:35:08 User:207.173.67.208 (→External links)
- 2005-07-23 03:11:04 User:AdamJacobMuller m (alink)
- 2005-07-19 15:54:45 User:Loxley (remove error of fact)
- 2005-07-14 03:35:22 User:Lowellian
- 2005-07-03 22:05:57 User:216.119.158.175 (→External links)
- 2005-07-03 20:49:16 User:216.119.157.226 (→External links)
- 2005-07-02 23:52:26 User:200.90.104.53
- 2005-06-28 12:45:13 User:Heron (fixed punctuation; removed "female")
- 2005-06-26 10:22:11 User:Loxley (plugging gap in explanation - see discussion)
- 2005-06-07 02:48:46 User:Taw m (mistakenly -> imprecisely)
- 2005-06-04 05:52:51 User:Jshadias m
- 2005-06-04 05:52:12 User:Jshadias m
- 2005-05-30 22:55:14 User:Joe Jarvis m (Copyedit)
- 2005-05-28 17:08:19 User:Cmdrjameson m (sp)
- 2005-05-10 18:33:33 User:DÅ‚ugosz m (→External links - add link)
- 2005-05-10 09:33:35 User:DVdm m (formatting)
- 2005-05-10 09:31:11 User:DVdm m (caveats and warnings)
- 2005-05-09 18:57:08 User:Loxley (see Talk)
- 2005-05-09 17:56:18 User:213.224.83.4 (emphasis - line spacing -- coordinate length time and length)
- 2005-05-09 17:38:43 User:213.224.83.4
- 2005-05-09 13:24:37 User:15.203.169.124 (emphasis - line spacing)
- 2005-05-09 13:17:28 User:15.203.169.124 (new line formatting)
- 2005-05-09 13:16:13 User:15.203.169.124 (important warning (format))
- 2005-05-09 13:07:38 User:15.203.169.124 (Combining equations - removed mathematical appendix)
- 2005-05-09 10:36:13 User:Loxley (→Mathematical Appendix)
- 2005-05-09 09:08:05 User:Loxley
- 2005-05-09 08:59:57 User:Loxley (keeping uppercase and lowercase consistent between examples)
- 2005-05-09 08:44:27 User:Loxley
- 2005-05-07 12:59:39 User:213.224.83.20 (time dilation, length contraction, relativity of simultaneity)
- 2005-05-06 15:57:53 User:Loxley m (link imaginary unit)
- 2005-05-06 10:51:37 User:213.224.83.20 ("Square root of -1" ==> "imaginary unit")
- 2005-05-02 18:54:49 User:Loxley m
- 2005-05-01 13:07:38 User:80.3.32.7
- 2005-04-23 19:23:59 User:Loxley (→See also)
- 2005-04-23 19:20:18 User:Loxley (→External links)
- 2005-04-21 10:53:41 User:Loxley
- 2005-04-08 10:29:48 User:Loxley
- 2005-04-03 01:41:36 User:Gruu m (Formatting after first image)
- 2005-03-24 10:27:16 User:Loxley
- 2005-03-23 19:35:26 User:24.177.99.197 (describe what the constant c is)
- 2005-03-21 04:48:19 User:Teorth (→See also - category)
- 2005-03-18 15:28:00 User:134.58.253.113
- 2005-03-14 20:05:58 User:Loxley m (two dimensional)
- 2005-03-14 19:59:30 User:Wwoods (tweaks)
- 2005-03-14 09:20:34 User:Loxley m ('seem')
- 2005-03-13 20:34:36 User:Loxley (italic heading)
- 2005-03-13 20:33:15 User:Loxley
[edit] From en:Talk:Special relativity for beginners
[edit] Mixing Time Dilation and Length Contraction
An anonymous user very properly deleted this approach (Could this user get an ID?). This is supposed to be a simple introduction so it would be good to get a conceptually simple approach to length contraction. To my shame I went 'too simple' but there must be a simple approach somewhere.
I took out some of the emphatic text added by the anonymous user, I think it may have been directed at me. I also shifted the warnings into the Caveats section, renaming this Caveats and Warnings. Loxley 19:15, 9 May 2005 (UTC)
Sorry for the anonimity. I didn't know one could get a free ID. I have taken an ID now (DVdm)
Good idea to move the warning. I'd like to re-insert the comment about the combination of the two equations. I have seen it happen quite often on the Web, specially by enthusiastic beginners, either to define some sort of invariant "spacetime area" X*T = X'*T', or to derive some sort of "velocity transformation" by comparing X/T with X'/T'. In each case the dilation and contraction equations are combined without realizing that they can only be valid together in the trivial case where all the quantities are zero: x = X = t = T = 0. Okay with you? Yes, its probably a good idea. Loxley 07:58, 10 May 2005 (UTC)
==Doesn't this belong in Wikibooks?== Oberiko 15:32, 18 Mar 2005 (UTC)
- I had the same misgiving. (I notice you didn't say "this text belongs in Wikibooks!".) I agree with you, this article is on the edge. There are two questions here however firstly, how far should an encyclopedia explain its topics and secondly what is the minimum coverage required to provide any sort of explanation at all? I think this article is a minimal rendition of special relativity in such a way that the theory is explained. The difficulty here is that the theory is conceptually challenging for most people. Loxley 17:30, 18 Mar 2005 (UTC)
- I think this material is excellent for Wikipedia but I'm not keen on the equations. Surely a text-only version would suit beginners better. However, all-in-all, I think this is a good article - Adrian Pingstone 19:48, 18 Mar 2005 (UTC)
- This is a great article. Although I do agree that it would be a pretty weird article to find in a real (print) encyclopedia, I think it's great. -Haon 12:32, 13 October 2005 (UTC)
[edit] 'c' as a conversion constant
The beauty of Minkowski's four dimensionalism is that it explains why there is a constant velocity for all observers. If a thing travels at a velocity such that its space-time interval is zero then all observers, no matter how fast they are travelling, will observe the thing to be travelling at c metres per second. This is why Minkowski's and the modern approach, is more fundamental than Einstein's original 1905 approach which relied on an assumption (based on the Lorentz invariance of Maxwell's equations)that the speed of the propagation of light in a vacuum is constant. Although Einstein's postulate that the speed of light is constant is correct it confuses students utterly. They go off and ponder how such a thing could occur and, being no Einsteins, and being equipped with no more than school physics, reject the whole of relativity theory. The modern approach overcomes this problem because it predicts that there is a universal constant velocity. In advanced texts 'c' is often not used at all because lengths are specified in light seconds rather than metres. Loxley 10:46, 24 Mar 2005 (UTC)
[edit] Thanks
I'm generally very critical of the Wikipedia project. But really, Thanks for this article, it's really good.
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- I also think this is an excellent article. I'm fluent in mathematics but not physics. After reading this article I realize now that I never understood special relativity before, and think I do now. Wow, we don't live in Euclidean space-time, we live in Minkowski space-time - mind blowing stuff! There was however one point in the article that I found confusing.
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- So: − (cT)2 = (vt)2 − (ct)2
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- I couldn't work out why this is so. If I understand correctly it might be clearer to write
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- So because length is invariant in space time: − (cT)2 = (vt)2 − (ct)2
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- (e.g. length is invariant under a change of frame of reference, so the length of Bill's space-time interval should be equal from both Bill's and John's point of view). BTW I loved the math.
[edit] Why i ?
I think this article needs more information about why there is a i in s2 = x2 + y2 + z2 + (ict)2 There is at least one person (me) that doesn't get it.
- Minkowski included the 'i' because Euclidean geometry applies on the surface of a sphere of imaginary radius. He reasoned that given that Euclidean geometry seems to apply in our local space then this was due to events being projected so that the observer is at the centre of a sphere of radius ict. In the first year or two after Minkowski's proposal it was probably believed that the observer at the centre of the sphere was no distance from the surface ie: 0 = x2 + y2 + z2 + (ict)2 (if we put r2 = x2 + y2 + z2 it becomes obvious that 0 = r2 − (ct)2). However, mathematicians had long known about non-Euclidean geometry and realised that you can get an almost identical result using real rather than imaginary time and proposing that the universe is entirely non-Euclidean. See the reference about the non-Euclidean form of relativity at the end of the main article. loxley 16:11, 2 August 2005 (UTC)
[edit] Too technical?
"Special relativity for beginners" is an introduction to special relativity for those who are just embarking on the subject. The article as it stands assumes a knowledge of Pythagoras's Theorem and the language, apart from the technical terms, is probably about reading age 18. Someone with a less accomplished mathematical and conceptual background could indeed understand that Special Relativity is an important theory that is complicated but could they really understand Special Relativity at all? If you think they could then perhaps we need a "non-technical relativity" article loxley 09:50, 5 August 2005 (UTC)
I think this is a very good article. However it could use in my opinion an extreamly basic introduction or section giveing a general idea of the theory for younger people, not prepaired for the math end.
This is a good article. I think it's sufficient; I'm 15 and can understand this easily. However, I'm nominating this for articles for deletion in order to drive home the point that this should be merged - the special relativity article should contain this material - forks are bad for the project. Furthermore, all articles should be approachable by anyone, even if it's about a complex subject - we approach increasingly complex subjects by having daughter articles. -- Natalinasmpf 16:44, 17 November 2005 (UTC)
[edit] Are intervals in space-time imaginary quantities?
The example given in the beginning (i.e. a body travelling at velocity v) is applied in the very special case of v=c, from which it is shown that for a body travelling with velocity c any interval is zero. But if we look at the trivial case v < c, then S = sq.rt ( t**2 ( v**2 - c**2 )) = t sq.rt ( v**2 - c**2 ) which is an imaginary quantity! Does it mean that all simple movements in our world are imaginary? Demaag
- Even if time were imaginary the determination of a complex length is problematical - we must not forget that the length is a vector - See complex number. However, the current wisdom is that time in GR is real and that displacements are bilinear forms governed by a metric tensor. This gives very similar results to imaginary time but involves a curious arrangement of two coordinate systems. Unfortunately most articles on differential geometry miss out a detailed discussion of the derivation of the metric tensor (cf: the work of Carl Friedrich Gauss) and hence fail to explain things properly - probably because the tutors do not want students rushing off at tangents. loxley 08:53, 30 August 2005 (UTC)
[edit] This is for beginners???
This is for beginners??? Beginners what? Beginners 2nd year honours physics degree? I seem to have a different idea of "for beginners". I would mean to be for a layman and a general reader.
We need more non-technical, layman's guides in science here. I really feel we are writing for ourselves and our peers too much, not for the real audience.
And, FWIW, I am a physicist!
Paulc1001 08:08, 6 October 2005 (UTC)
- I largely agree with you; it may however be a useful introduction for beginners with a mathematics background. Thus, I'd rename it: "Special relativity for mathematicians".
- Harald88 18:40, 17 November 2005 (UTC)
The problem is that the intellectual spectrum between school physics and tensor math is huge. This article is half way along the spectrum. Why don't you mock up a "Special Relativity for Absolute Beginners" here? loxley 14:38, 6 October 2005 (UTC)
Loxley, you're right and that's a problem alright. But it can't be a harder problem than the Physics itself I guess! Even Hawking wrote a book with just a single equation in it. Actually, I was thinking of those without even high school physics, that's quite a lot of people! :-)
Writing such a simplified article is exactly what I intend to do, that's how I came here in the first place. I'm already doing this elsewhere and I plan to extend it to as many technical articles as possible (not just in Physics, I'm an ex-physicist now and have very broad interests) eventually when I can get the time.
Wanna help??:-) Paulc1001 17:45, 6 October 2005 (UTC)