Talk:Introduction to special relativity/Archive 3

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The approach of this article

Currently, this article takes the geometrical path into SR, the path proposed by Minkowski. Previous editors have believed, and I concur with them, that the geometric approach is easier to understand and appreciate for beginners rather than the popular science book approach, starting with Einsteine's postulates and working through various paradoxes and thought experiments. I say this from personal experience, because I didn't understand a word of relativity till I studied the geometric approach. Suddenly, everything seemed to fall into place. Of course there is no ground for saying that Minkowski was right and Einstein was wrong, and proper comprehensive coverage demands that we discuss both viewpoints. However, this is a task left to the main article. This article is an introduction because it sacrifices comprehensiveness to deal with selected facets clearly and analytically. As for importance, Minkowski is rarely mentioned by name, what is mentioned is the Minkowski space. Loom91 18:19, 29 September 2007 (UTC)

Modern SR, as promulgated by Einstein after 1910, is the physics of Minowki spacetime. There is no Einstein version and Minkowski version. Dypteran 16:40, 30 September 2007 (UTC)

At first sight, it looks like you essentially reverted to a version before user Geometer started working on it. I will wait a while until the avalanche of resulting admendments to this substantial edit will have settled down a bit :-)

DVdm 20:54, 29 September 2007 (UTC)

Since most of the edits essentially involved arbitrily removing large amounts of content resulting in a significantly less readable article without any prior discussion, essentially yes. However there are also a few differences. Let's hope we are not sitting in the leading edge of an edit war. Loom91 21:25, 29 September 2007 (UTC)

;-) DVdm 21:40, 29 September 2007 (UTC)

Merger

This article has changed from a short tutorial in how SR is the physics of Minkowski space see http://en.wikipedia.org/w/index.php?title=Introduction_to_special_relativity&oldid=144699477 to a full competitor with the main article. The main article is pretty good. Dypteran 16:35, 30 September 2007 (UTC)

These sort of suggestions have been tried countless times in the past and have always been stricken down without exception. Recently the seal of community approval was reinforced by the featuring of Introduction to general relativity. This merge proposal doesn't have a snowball's chance in hell to succeed. Loom91 17:55, 30 September 2007 (UTC)

The introduction to general relativity is different because the main article is far more complicated than special relativity. The people who have edited special relativity have made it fairly simple. What has happened in this case is that the introduction has been expanded recently by Loom91 to copy the main article. This is a pointless exercise and damages Wikipedia. Dypteran 14:35, 1 October 2007 (UTC)

Hmmm, I don't see much of a difference between the old and new versions. What we should do is write this article so that an interested lay person (e.g. a high school student) who knows nothing about special relativity can understand the basics so that he/she can more easily understand the main article. Count Iblis 17:53, 30 September 2007 (UTC)

I think the current article can be understood by the interested high-school student. Loom91 17:55, 30 September 2007 (UTC)

I agree, however, I do think that more results must be derived in this article. One can also write new wiki articles for this purpose and link those from this article to make room for that. E.g. a derivation of the Lorentz transformation using light signals, a derivation of the relativistic formulae for energy and momentum by considering collisions, etc. etc. All of this is high school level stuff... Count Iblis 18:06, 30 September 2007 (UTC)

Surely an intro is a preamble to the main text rather than an amplification of it. Also, using light rays distracts the reader from the idea that SR is the physics of spacetime. Dypteran 14:35, 1 October 2007 (UTC)

Since wikipedia is an encyclopedia and not a textbook, we do not include derivations or proofs unless they are particularly interesting, important or othewise of wide interest. As a general rule, we seek to describe rather than analyse. Loom91 18:18, 30 September 2007 (UTC)

Um, I *do* see two propositions complete with proof in the part that you restored earlier today. You might so some rewriting there ;-) - DVdm 20:32, 30 September 2007 (UTC)

Note the particularly interesting escape clause. Loom91 07:19, 1 October 2007 (UTC)

I have just restored the merge notice. There is a large amount of content in this article that should be merged with the Special relativity article. In fact the structure of the two articles is quite similar and, where it treats reference frames and the Lorentz transformation this introduction does not improve on the main article. These parts of this article should, in my opinion be merged with the main article. Where this intro is indeed different is that it explains the underlying basis of SR as the physics of Minkowski space in a simple way.

This issue of Wikipedia as an encyclopedia is interesting. What happens in an encyclopedia is that experts consider the current state of an item then summarise it for the lay reader. An encyclopedia is not simply a copy of previous encyclopedias. The explanation of SR as the physics of Minkowski space is probably new for an encylopedia but it is indeed correct and very useful for new readers.

I have had a problem following why Loom91 and DVdm feel that Minkowski space is so problematical (there was even a point of view notice put on this article at one time by one of these users). I still dont really know whether it is because they feel that SR as the physics of Minkowski space is an incorrect analysis that should be hidden in some way.

The big difference between the version suggested above ( http://en.wikipedia.org/w/index.php?title=Introduction_to_special_relativity&oldid=144699477 ) and this version is that the current version obscures a simple truth and then rehashes some of the content of the main article.

The main article is actually quite simple, it does not need Lorentz transforms and reference frames explained elsewhere but what it misses is the underlying rationale for SR. So, I would propose that this article goes back to an explanation of the underlying rationale for SR and the parts that are clearly duplicates of the main article are merged back with it. Robinhw 08:39, 1 October 2007 (UTC)

I have been thinking about this problem and it seems to me that there are two separate issues. The first is a slight editorial dispute where some people think that SR is the physics of Minkowski space and physical laws are constrained by this as a result of Noether's theorem whilst some other people are not entirely convinced that this is the case. The second issue is what an introduction should be like. Given that the main text is already a fairly simple introduction this second issue has three alternatives:

1. The intro should rehash the main text in different language (the current version).

2. The intro should provide an orientation to SR (ie: http://en.wikipedia.org/w/index.php?title=Introduction_to_special_relativity&oldid=144699477 ) to save people from the outset from believing that SR is a Euclidean theory with dynamical adjustments.

3. The intro should be combined with the main text to provide the orientation in (2).Robinhw 11:47, 1 October 2007 (UTC)

• I would vote for option (2). Dypteran 14:35, 1 October 2007 (UTC)

• Definitely vote for option (3). "An Introduction to" does not really belong in an encyclopedia. It can only cause redundancy and inconsistency, specially in a Wiki-environment with an unlimited number of authors and views. It is bound to confuse the casual and lay-reader. DVdm 17:10, 1 October 2007 (UTC)

• I find this list of choices to be very POV to me. For option (1), I do not see this version as being a rehash. Instead, the new section which is delving into reference frames and the relationship of SR and Newtonian mechanics is a very important way to introduce SR, and should be retained. For option (2), I never saw that earlier version as being at all an introductory text. Instead it was throwing relativiy novices to the wolves by immediately introducing a very advanced concept and rehashing the main points of the main article using that advanced mathematics. Option (3) is not POV, but I do feel that this would clutter up the main article.
  This article should be mostly in plain English and introducing the issues which distinguish SR from Newtonian physics. This is not the say that the concept of Minkowski space cannot be used here, but it must be part of a primarily English-based (instead of a primarily mathematically-based) article. --EMS | Talk 18:52, 1 October 2007 (UTC)

Yes, there are two problems. The first is that some editors see SR as the physics of Minkowski spacetime. I am one of these. I do not regard this as a POV but mainstream modern thought on the matter. The trouble is that by 1909 Einstein was under heavy attack for the ontological basis of his theory. The "speed of light" is a compound constant (length/time) and the assumption that physical laws should be the same between reference frames is just an edict, not a self evident truth (the action is not invariant during Galilean transformations). As Weyl pointed out, it was Minkowski who gave SR a respectable ontology. The original article uses the same level of maths as the article on the Pythagorean theorem. The main special relativity article is actually quite simple but doesnt explain Minkowski space. Robinhw 08:47, 2 October 2007 (UTC)

The idea that Minkowski space is "easy" or "introductory" is what is getting to me. It is not. It requires a sense of space and an ability to read mathematical expressions that I have found to be less than natural. As a result, Minkowski space makes for a lousy introduction to SR on its own. IMO, the issue to be dealt with here is one of how does SR differ from Newtonian physics? You need to first lay out the basics of what Newtonian physics is and how it was modified in SR. Then you can bring in Minkowski spacetime as the paradigm that underlies SR, but to be honest with you the Lorentz Transformations are also needed. --EMS | Talk 16:46, 2 October 2007 (UTC)

This sense of the role of space in physics is special relativity. If people don't understand it they don't understand SR. The LT's are just a combination of gamma*time and gamma*phase, explain time dilation and phase and you have the LTs. The LT is not fundamental nowadays, it is the metric that is fundamental. Robinhw 09:21, 3 October 2007 (UTC)

V good, thanks. Geometer 10:32, 3 October 2007 (UTC)

Robinw, I have seen quite some books on relativity, but never seen one where it is stated that "The LT's are just a combination of gamma*time and gamma*phase". Can you give a few relevant references for that? DVdm 11:09, 3 October 2007 (UTC)

• BTW I would vote for (2) but I am easy about (3). It is crucial to explain from the outset that SR is not an adjustment to Euclidean ideas or students will get the whole thing wrong. Robinhw 11:29, 2 October 2007 (UTC)

Firstly, The main article is considerably more detailed and difficult (it uses Einstein summation convention among other advanced things) than this introduction, which focuses on the basics. Secondly, this article very clearly sets out that the most economical and natural formalism for SR is the Minkowski space. Thirdly, the relevance of introductory articles to Wikipedia has been settled multiple times in the past. We don't need to drag up that debate once again. Loom91 19:50, 2 October 2007 (UTC)

The debate here is about what should go in an introductory article. The approval of this type of article in Wikipedia is not an approval for introductory articles that duplicate the main text, so, yes, there is a need for debate. Have your changes duplicated the main article? Does the main article explain the points that you duplicated (frames of reference, Lorentz transformations, Galilean vs Einstein relativity as clearly? That is the issue. I think the main text is clear and simple on these matters and does not need duplicating here. In the same way as EMS says that things in the intro would "clutter up" the main article I believe that these duplications clutter up the intro. Robinhw 09:21, 3 October 2007 (UTC)

OK, I have included Loom91's desire to include frames of reference etc. in a simple way. Geometer 10:28, 3 October 2007 (UTC)

Regarding Geometer's edit

I undid your edit. To me it looked like a blind revert to some old version with the addition of your personal (i.m.o. very poorly worded) section. Frankly, considering the recent efforts by others, your contribution looked a bit like vandalism. Perhaps you could first propose here what you intend to do with the article. DVdm 11:03, 3 October 2007 (UTC)

Look, read the article before aggressively reverting. It now has the reference frames and LT as EMS and Loom91 want and the Minkowski space that Robinhw and others want. It just has them in the right place. Geometer 11:09, 3 October 2007 (UTC)

A lot more happened than just putting "in the right place". Reverted again. I'll leave it to others to undo your next revert. DVdm 11:15, 3 October 2007 (UTC)

You are reverting without even discussing the fact that Loom91 and EMS's requirements have been met. Please explain "a lot more happened". Geometer 11:49, 3 October 2007 (UTC)

I'm not going to waste my time discussing this. If others don't find it obvious, then so be it. DVdm 12:24, 3 October 2007 (UTC)

I was just looking at the latest version and it changed. Geometer's new version was much better than the old one. It was straightforward and modern. What is going on here? I thought Geometer's version was the original and Loom91 had changed it, causing all the trouble. I cant be bothered with this anymore. Robinhw 16:43, 3 October 2007 (UTC)

Geometer's version is not as has never been a proper introduction to SR. Instead it immediately dives into a very advanced concept (Minkowski spacetime) which is highly technical and inappropriate for a reader who may have limited mathematical and/or physics training. So yes it is straighforward and yes it is modern, but it also utterly fails to serve the intended audience!

I also chaffe at the implication in Geometer's version that SR is the work of Hermann Minkowski and Emmy Noether. Albert Einstein is the one who initially created SR and for that he deserves the primary and immediate credit. This is not to dismiss the work of Miknowski and Noether, but please let's put it into the proper context. In fact Noether's work is so advanced that it does not belong here at all. Minkowski's work OTOH does belong here, but a scientifically novice reader needs to be introduced to a number of other concepts before the concept of Miknowski spacetime is thrown at them.

Please, let's continue to develop this article into a proper and relatively non-technical introduction to SR, and not go backwards. Please let's first explain how SR differs from the "common sense" view of Newtonian physics and then go on the show the reader how these changes arise from the our existance being in a Minkowski spacetime instead of a Newtonian spacetime. --EMS | Talk 17:39, 3 October 2007 (UTC)

It is the problem of explaining how SR differs from Newtonian physics that the article should indeed address. The difference is entirely due to the existence of Minkowski space. Teaching SR by first recounting the Galilean version of relativity and Newton's laws is known to cause immense problems. Most students believe that relativity theory is a dynamical adjustment of Euclidean space and get lost. The article favoured by Geometer explains Minkowski space in a simple way and then derives the results of relativity from this description, this is a thoroughly modern approach and avoids the confusion of the approach pursued in old popular physics books and encyclopaedias. What is odd here is that you must know that the modern approach is the only way to teach graduates relativity theory but are insisting on the confusing 1905-1909 approach for lay people. When there is a perfectly good explanation of Minkowski space for lay people available as a previous version of this article your insistence on the old approach seems odd. I am putting the article back to Geometer's version then leaving this debate. Perhaps you could just read that version and decide whether Minkowski space is really inexplicable to lay people. Robinhw 18:22, 3 October 2007 (UTC)

Reverted back. You can't possibly be serious about that dreadful section. - DVdm 18:33, 3 October 2007 (UTC)

I support DVdm on this. The geometric approach is already used in wikibooks, which is where it belongs. OTOH, this is not a textbook but instead is supposed to be an introductory level article. Once again: You are throwing the novice reader to the wolves when you immediately start into Miknowski spacetime. There are questions that need to be answered first: What is special relativity? How does it differ from Newtonian physics? Why is it claimed to be self-consistent? Why should a geometric treatment of this issue be done? You may scoff at the historical approach, but it represents the intellectual development of the theory and therefore when IMO is the path of least resistance for a novice.

To be a good article, this one needs to start out very much English-based and simple. Once the basics have been stated, then it can ratchet up the level of math and intellect needed to understand it as one goes on. --EMS | Talk 22:09, 3 October 2007 (UTC)

Let's take this edit war off the air and hammer out things here first. Geometer, why don't you give a comparison of your version and the current one, specifying what changes you think must be made and why. This debate is too much about points of general principle and not enough about the specifics of this article. A more focused and ordered discussion should help. In the meantime, please temporarily refrain from reverting back to your prefered version. Loom91 19:08, 3 October 2007 (UTC)

Loom - I for one think that the disagreement is about basic structure and article organization. Is this going to be solely a treatemt of Minkowski spacetime, or is it going to be more historically based? --EMS | Talk 22:12, 3 October 2007 (UTC)

A historical approach would go through Maxwell's equations, the Michelson-Morley experiment and Einstein's postulates to enter SR. Instead, this article gives up a brief description of the relevant portions of Newtonian mechanics and then takes the purely geometric approach to describe special relativity, completely bypassing Einstein's postulates (which are then derived). That doesn't seem very historical to me. As it stands now, the article postulates that transformations of reference frames can be represented by rotations in a Minkowski space and uses this basic fact to derive the important dynamic consequences of SR. A similar approach to a different part of physics can be found in Feynman's QED, where he repeatedly ridicules the historical approach to pedagogy as backward and unnecessary. I concur with Geometer and Robinhw that the approach here should be geometric for maximum clarity and accesiblity, but I believe the current version is geometric enough and Geometer's preffered version is merely unclear. Loom91 09:19, 4 October 2007 (UTC)

What are we trying to achieve? For me it is the avoidance of readers who understand relativity as a dynamical adjustment of Euclidean phenomena. I would guess that over half of undergrads believe that relativity is an adjustment within Euclidean space and 95% of lay readers believe it. This means 5% of people who have been interested in relativity know what it is about. The other thing I want to avoid is people believing that relativity involves things that can only be calculated by the point observer. This is a common error in which students believe that observers only know their local photons and cannot calculate events in a whole reference frame.

Both these errors can be avoided by concentrating on spacetime from the outset. Tell readers that relativity is the physics of spacetime from the start.

I came across this article about a year or two ago and was really surprised that Wikipedia had something that summarised modern thinking and avoided the dynamical approach that misleads students so badly. I tried to polish it up to get it good article status.

I agree with EMS, the disagreement is about structure. My idea of an ideal structure is broadly what I found here in the first place:

1. Introduce the idea that relativity has changed since 1905.

2. Describe Minkowski space in simple terms.

3. Use Minkowski space to derive time dilation and physics of simultaneity.

4. If necessary, bring in frames of reference as a comoving lattice of synchronized clocks. Explain that the relativity of simultaneity means that clocks outside the frame of reference will progressively differ which is why you must define such a lattice

5. If necessary the LT can be easily derived as the net effect of time dilation and phase.

5. Refer readers to the main article for anything else.

The problem with bringing in reference frames at the start is that without being introduced to the physics of simultaneity readers will have no idea that the frame is really there to avoid the clock problem. Comoving things have clocks that stay in sync for a comoving observer, all other clocks go out of sync.

The problem with stressing the "relativity" of relativity is it introduces a dynamical approach that readers can misunderstand as an adjustment within Euclidean space. I would leave the "relativity" of relativity to the main article.

The LT is just the net effect of time dilation and phase.

Well, thats my two bits. Any comments? Geometer 09:18, 4 October 2007 (UTC)

I think the main point here is whether to introduce reference frames in the beginning. Well, Wikipedia is not the place for original scientific research. A reference frame is a method of stitching up the spacetime in the time direction, an identification of space points at various points of time. Reference frames are essential to record and report measurements unambiguously even in classical physics, where there is no question of relativity of simultaneity. Your interpretation of reference frames is non-standard and therefore unsuitable for inclusion in an encyclopedia article unless you get them published in a peer-reviewed journal. In the Minkowski formalism, the basic postulate is that transformations of reference frame can be described by rotations in the Minkowski spacetime (the invariance of the metric under rotations is a feature of the mathematical definition of the Minkowski space, not a dynamical postulate). Loom91 09:27, 4 October 2007 (UTC)

Are you certain that you are not using the concept of a reference frame as a synonym for a coordinate system? In relativity reference frames are essential because of the clock problem due to the relativity of simultaneity. A reference frame is not only a coordinate system, it is an infinite lattice of synchronised clocks. The problem in teaching relativity is that students are not taught this properly:

"In stating the Measurement question, we did not explicitly ask students to consider a lattice of rulers and clocks by which to determine the position and time of events. We expected students to generate such a lattice spontaneously in order to make the measurements we requested. Very few students applied this formalism in determining the length or speed of an object." http://www.physics.umd.edu/perg/papers/scherr/dissertation/ScherrDisstn.pdf

The idea of a reference frame as a lattice of rods and synchronized clocks is standard physics and it is also an obvious corollary of the physics of simultaneity and Einstein's definition of a "body of reference" as comoving objects. Without the clock problem (the physics of simultaneity) you only need a coordinate system, not a reference frame. Geometer 10:53, 4 October 2007 (UTC)

Even without the relativity of simultaneity, you need a reference frame. A coordinate frame is optional and can be done away with (as is done in texts like VI Arnold's Mathematical Methods in Classical Mechanics). A coordinate frame only specifies an origin and a scale, allowing you to define vectors (essentially, imposing a vector space structure on an afine space). A reference frame is far more fundamental. It specifies which events are considered to be spatially identified at different instants of time. This is same in both classical physics and SR. What's different in SR is that the concept of instants of time itself becomes relative, complicating the formalism. But we don't need to enter into such highly technical details in an introductory article. Loom91 11:04, 4 October 2007 (UTC)

The idea of a reference frame as a lattice of clocks is not particularly technical (see my version of the article) but it is important. Teachers of undergrads have pointed out on many occasions that the failure to understand this aspect of relativity is pivotal to a mistaken understanding of the whole subject:

"One of the most important things about how we measure the properties of moving objects is the idea of the simultaneity of events (or lack thereof) and the synchronization of clocks. What do we mean by the synchronization of clocks? It is perhaps not what you think. We construct a reference frame with numerous clocks placed at say 1-meter increments (position is given in meters and time is given in meters). If we did this in three dimensions we would have a cubic lattice spanning all space." http://webphysics.davidson.edu/physlet_resources/special_relativity/illustration1.html

I agree about coordinate systems in general but in SR we are teaching the physics of flat Minkowski spacetime and this is indeed understood using a frame of reference with embedded coordinates. Thorne and Blandford explain this in their book (http://www.pma.caltech.edu/Courses/ph136/yr2004/0401.1.K.pdf ). Geometer 11:22, 4 October 2007 (UTC)

Since all these 'lattice clocks' as you call them are synchronised in an inertial reference frame (the only type we are dealing with), there is no conflict with the reader's intuition. An inertial observer can identify every event uniquely with 4 coordinates. Why is it necessary to spell out the details of synchronisation in an introductory article? We are not teaching an undergrad course on SR, we are presenting a very brief review of the subject, and we are definitely not trying to teach problem solving skills. Loom91 11:44, 4 October 2007 (UTC)

You lot have been busy. I dont think its necessary to bring in frames of reference at all in an introduction. Einstein is to Minkowski as Heisenberg is to Schroedinger. Sure, you can show that they are saying the same thing but one is much clearer than the other. Minkowski and Schroedinger are clearer than Einstein(1905 edition) and Heisenberg. Einstein is remembered by physicists for his photo-electric work and his GR based on Minkowski space. Einstein's 1905 SR is just the most amazing intuition in history. There was no reason in 1905 to suppose that all physical laws would be the same between moving observers! The speed of photons constant, crazy! It took Minkowski and many others to make sense of things.

If you bring in frames of reference at the start youve then got to show on the basis of dynamical arguments about the motion of photons that the Lorentz transformation demonstrates an underlying, non-dynamical Minkowski space. No wonder students get confused. Leave Einstein out except as a side mention and go straight for Minkowski. Leave frames of reference and the LT for the main article where they are already covered.

I think Loom91's point about lattices of clocks is reasonable. You can only understand the reason for frames of reference if you understand lattices of clocks and the physics of simultaneity so frames of reference should be left out of an intro, its just a step too far. Cut the intro back to an explanation of Minkowski space and tell the reader to go to the main article for anything else. But if you are going to include frames of reference youve got to explain why by using lattices of clocks and arguments about simultaneity.

The reference above http://www.physics.umd.edu/perg/papers/scherr/dissertation/ScherrDisstn.pdf is really cool. It agrees with my experience, physics undergrads and even graduates dont understand relativity if they are taught it using the old approach. Why are Loom91 and EMS so keen to just repeat an approach that is known to fail? And to fail catastrophically. I cant understand why they are so keen to do it. Dypteran 13:39, 4 October 2007 (UTC)

I agree, I guess that the comments by Warren Siegel apply to this article, see here  :) Count Iblis 15:26, 4 October 2007 (UTC)

Very amusing, but i.m.o. not applicable. DVdm 16:54, 4 October 2007 (UTC)

Siegel has made similar points before. His opinion is that you can usually explain the the theory (whatever that is) straight away and you don't need to go through the often very confusing historical way it was discovered. Introduction is one thing, history is something else. Count Iblis 17:40, 4 October 2007 (UTC)

Dypteran, I undid that version by Geometer. Did you actually have a look at that section? DVdm 16:48, 4 October 2007 (UTC)

It was technically accurate but already covered in the main article. As you object to it and I am against putting too much in the intro I cut it. Dypteran 17:47, 4 October 2007 (UTC)

I have reverted yet again, in order for me and others to avoid having to undo (again) some other technically "accurate" things like

• "The path taken by a thing in both space and time is known as the space-time interval",

Sheesh. This is getting silly and boring. DVdm 18:27, 4 October 2007 (UTC)

This is sick. All that I am seeing are the novice readers being sacrificed on the altar of Minkowski spacetime. I agree that the use of Minkowski spacetime to teach relativity is a wonderful idea, but this is an encylopedia article, not a college-level physics text. The first chance I get, I am going to rewrite the lead to state what relativity is, what Einstein's postulates are, and what predictions come from it. Just plain flat out. Is that going to teach the reader relativity theory? Not at all, but it will tell them in a nutshell what relativity is! After that we need to introduce some fundamental concepts. Maybe that thesis cited above can help us to properly describe relativity theory, but once again the idea of throwing Minkowski spacetime at an reader who is unprepared for it yields nothing but a reader who comes, gets bewildered, and leaves without having learned anything! --EMS | Talk 19:00, 4 October 2007 (UTC)

No, its going to display what you and the few others who sit on the relativity articles think relativity is. Modern relativity is the physics of flat Minkowski spacetime, not Einstein's postulates. This can and must be explained so that beginners understand it. Dypteran 09:12, 5 October 2007 (UTC)

Fully agree. Wikipedia is not a first year physics course for physics/math students. The interested student can and will find his way and lose his alleged confusion in the main article and its satellites like Minkowski spacetime. Writing an introductory article with that marginal part of the Wiki-reading population in mind, will only produce more Usenet (and Wiki!) crackpots and trolls. DVdm 19:16, 4 October 2007 (UTC)

I agree completely with EMS. Propositions and proofs?! As an introduction to SR, this article is a hopeless failure. Those who insist otherwise, please provide evidence. Do you have experience teaching SR? Have you read the physics education literature on students' difficulties in grasping SR? Please go and make a new article on the Minkowski approach to SR, if you wish, but leave this page to those with a genuine interest in making SR accessible to the general reader. Timb66 02:51, 5 October 2007 (UTC)

Yes I do have experience in the field. That is the point. This article is being changed into an old fashioned classical physical text on SR from a text that explained the underlying concepts. Now it overlaps the main article everywhere, muddles the point about Minkowski spacetime and takes no notice at all of papers on teaching SR like http://www.physics.umd.edu/perg/papers/scherr/dissertation/ScherrDisstn.pdf . This is scientific evidence that your approach does not work. The whole point that various people are making is that making this into a copy of 1960's articles on Einstein's 1905 paper is not explaining SR. Look, to be blunt, its obvious that some of those who are pressing for an old style intro have the problems described in http://www.physics.umd.edu/perg/papers/scherr/dissertation/ScherrDisstn.pdf, and yes, there are plenty of physics teachers who dont understand the relativity of simultaneity and dont understand the importance of Minkowski spacetime. Check yourself out on the examples in the paper to make sure you are not one of them. Dypteran 09:04, 5 October 2007 (UTC)

THIS IS AN ENCYCLOPEDIA ARTICLE. THIS IS AN ENCYCLOPEDIA ARTICLE. THIS IS AN ENCYCLOPEDIA ARTICLE! How may time do I have to tell you that THIS IS AN ENCYCLOPEDIA ARTICLE?!!! Do you have any idea what a novice reader (who may lack even high school level training in math and science) sees when they come to this article as you want it to be? "Minknowski! Noether! Pythagoream Theorem! Spacetime Interval! Minkowsi (again)!" all interspersed by a bunch of mathematical equations. I look back at how I would have felt about this article when I was about to enter college, and I would have been more confounded by it than by the 1960's books that you so deride! There is no early mention of the contancy of the speed of light, nor of time dilation, length contraction, E=mc², or anything else that defines relativity for the average man on the street. To make matters wrose, your version treats Einstein as some figure of historical interest who had little to do with relativity theory instead of being the person who first put all of the pieces together and made Minkowski's work possible.

I cannot impress on you enough that this is not the place to write an introduction to a semester-long college level course on SR. We have an allowance of 50K - 70K visible characters with which to make the needed points. It does Wikipedia no good to have its introduction to SR be so bewildering. Under your version a novice reader will comes away thinking that special relativity was created by Minkowski and Noether and has something to do with the Pythagoream Theorem if they take anything away from it at all!

As for that thesis that you are so in love with: I don't see it as a grand celebration of the wonders of Minknowski spacetime. To quote from the end of Chapter Two:

Special relativity offers instructors an opportunity to channel student interest in modern physics into a challenging intellectual experience. For most people, the implications of special relativity are in strong conflict with their intuition. For students to recognize the conflict and appreciate its resolution, they need to have a functional understanding of some very basic concepts.

Furthermore, the problems that Ms. Scherr identified includes misunderstandings of what a frame of reference is and how the times of events are inferred. In fact, when I look at Chapter 6 (Conclusions), Ms Scherr states that

The results of this investigation strongly suggest that a meaningful understanding of relativity requires a sound basis in nonrelativistic kinematics.

Nowhere in her conclusions is Minkowski spacetime mentioned at all! --EMS | Talk 14:54, 5 October 2007 (UTC)

Well, modern special relativity was created by Minkowski in 1908 on the basis of Einstein's analysis. Yes, SR IS an extension of Pythagoras' theorem being the physics of Minkowski space, a space with an extra dimension. I agree with Scherr that the nature of a frame of reference, as a lattice of synchronized clocks, does need to be taught but the need for this frame can only be understood when it is realised that in Minkowski spacetime moving clocks go out of sync. Without this insight a frame of reference reduces to a coordinate system. This is not too difficult to teach. I am surprised that you reject it. It seems to me that you have taken away the wrong lessons from Scherr. You were clearly taught the old fashioned way so will find the path from Pythagoras through Minkowski to Einstein bewildering but if students are taught this from the outset they will not be so puzzled. Dypteran 10:50, 6 October 2007 (UTC)

Something that bothers me is that it seems that some of the contributors dont really believe that special relativity is true. The logical consequence of flat Minkowski spacetime is the Rietdijk-Putnam argument. It is simply the consequence of the relativity of simultaneity but it has led some physicists and philosophers to reject SR. Reading DVdm and Loom91's statements on only being able to compare reference frames at the origin of coordinate systems and rejecting the Minkowskian interdependence of space and time (DVdm edited this out as POV(!) and Loom91 believes time is totally separate) they cannot support the Rietdijk-Putnam argument and it seems that they are not onboard the theory of special relativity at all.... This is a curious state of affairs where those controlling an article are opponents of its content. Dypteran 14:25, 5 October 2007 (UTC)

If there is such a misunderstanding present on the parts of others, I will be happy to help get it resolved. However, as important as that issue is, it pales in the face of dealing with your improperly advanced approach. --EMS | Talk 14:54, 5 October 2007 (UTC)

"Reading DVdm and Loom91's statements on only being able to compare reference frames at the origin of coordinate systems and rejecting the Minkowskian interdependence of space and time" ==> IIRC I threw that silly part away. The POV I edited out was this one by you, with edit summary "Minkowski is central to modern SR - its disturbing that some editors reject this." DVdm 16:05, 5 October 2007 (UTC)

Lead rewritten.

It is done as I outlined above. Once again, the goal is to briefly and succinctly describe what special relativity is! Note that this description is self-contained. If the reader gets no further than the lead, at least they will have seen a quick and dirty but correct description of special relativity. --EMS | Talk 04:34, 6 October 2007 (UTC)

Good job, thanks. But note that the 2nd postulate is that the speed of light is invariant (the same for all inertial observers), not that it is constant. Timb66 13:06, 6 October 2007 (UTC)

Confusing ontology with evidence

The current intro is a mistake. The ontology of modern SR is clear. The universe is a Minkowski space with the conservation laws of physics dependent upon the symmetries of this space. In other words SR is the physics of Minkowski space. The evidence for relativity depends on MMX, Einstein's work on electrodynamics etc.

Count Iblis, Robinhw, Geometer and myself understand this distinction.

==> I'm not sure about Geometer (thinking that physics is just a branch of mathematics: "It is sufficient to understand Pythagoras' theorem to understand SR"), and I'm not sure about you ("Minkowski did start with imaginary time and the new way of doing SR does really have less separation between time and space than the imaginary formulation" remember?), but apart from that, most us understand the distinction pretty well. Straw man - DVdm 17:06, 6 October 2007 (UTC)

The purpose of an encyclopedia is to summarise modern thought, not to rehash other encyclopedia articles. The current article is just a rehash of other second rate articles and a mistake. It is clear from the discussions above that Loom91 and DVdm have a problem with accepting the modern theory and I am not sure about EMS. It is tragic that these editors have got their way simply because they are always here. They should try reading some of the refs below and summarise these as an intro rather than rehashing previous mistakes.

==> I have no problem with accepting the modern theory. No one here has that problem. Another Straw man - DVdm 17:06, 6 October 2007 (UTC)

Special relativity is the physics of Minkowski spacetime

Nearly all twentieth century and twenty first century physics textbooks describe special relativity as the physics of flat, Minkowski spacetime.

Einstein(1916):"It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence."

Roger Penrose (1998): "The idea that the history of the universe should be viewed, physically, as a four-dimensional space-time, rather than as a three dimensional space evolving with time is indeed fundamental to modern physics."

Hermann Weyl(1918):"The adequate mathematical formulation of Einstein's discovery was first given by Minkowski: to him we are indebted for the idea of four dimensional world-geometry, on which we based our argument from the outset."

Kip Thorne and Roger Blandford in their Caltec physics notes say: "Special relativity is the limit of general relativity in the complete absence of gravity; its arena is flat, 4-dimensional Minkowski spacetime."

Sean Carroll says: "..it makes sense to think of SR as a theory of 4-dimensional spacetime, known as Minkowski space."

Dypteran 14:57, 6 October 2007 (UTC)

==> You are consistently over-making your point. You are also consistently over-forgetting that you are on the talk page of an introduction to a subject, targeted at a lay public. The quotes and references you give are excellent. Carrol's book is superb, but alas, it is on a different subject and targeted at an entirely different public. You can safely stop embarrassing yourself now. Try to concentrate on improving the Minkowski spacetime article - see you there. DVdm 16:16, 6 October 2007 (UTC)

I will second these comments. To be blunt about it, the main special relativity article is in need of a good rewrite: That article currently is a hodge-podge of all sorts of contributions that have never been put into a coherent, well through-out whole. Perhaps it could start out with a breif introduction to Minkowski spacetime. At the least, that would be a much better place for you to apply your insight, as that is the one that is intended to be the technically accurate article. Even so, I also remind you that the Minkowski spacetime material does appear in wikibooks:special relativity, where I have no quibble with its presense; and that Ms. Scherr's thesis did not conclude that the use of Miknowski spacetime is the best way to teach students the fundamentals of SR. --EMS | Talk 03:31, 7 October 2007 (UTC)

The second postulate

Timb66 wrote that the second postulate is:

... that the speed of light in vacuum [as] measured by an observer does not depend on the motion of the light source.

This is not a correct statement, and in fact when combined with Newtonian physics that statement is the basis of luminiferous aether theory. A look at Einstein's initial SR article shows that he first presented the second postulate as being

light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body.

So as stated by Einstein, both the fact that the speed of light is c and the fact that this speed is independent of the motion of the source are stated. IMO, the constancy/invariance of c is the real issue here. I have tried to create wording now that reflects this invariance (stating that the speed of light is the same for all inertial onbservers). Hopefully that will prove to be a good/consensus way of representing the second postulate. --EMS | Talk 03:57, 7 October 2007 (UTC)

I noticed that both you and Timb66 first had reinserted and then later removed the phrase "which is now defined as being 299,792,458 m/s". I think that this indeed should only be mentioned after a statement about the universally successfull testing of the theory, which is what I have done. DVdm 09:36, 7 October 2007 (UTC)

I concluded that the exact speed was superfluous in that context, and gather the Timb66 agrees. I like the purpose of your edit, but did amend it somewhat. --EMS | Talk 16:07, 7 October 2007 (UTC)

Suggestion for an extra sentence

Perhaps adding this sentence to the end of the first paragraph of the lead may help things a bit:

In special relativity, space and time are treated as being the interchageable aspects of a 4-dimensional continuum called Minkowski spacetime.

I worry that even this may be a bit too advanced for some readers. OTOH, it does drop some good hints as to the real nature of SR. Also, if a reader is enough "behind the 8-ball" when they come here they won't get much out of the rest of this intro anyway, in which case the extra text doesn't hurt things. Comments or suggestions, anyone? --EMS | Talk 04:12, 7 October 2007 (UTC)

I would rather keep that as an 8-ball opening line for the section The Minkowski formulation: introduction of spacetime. DVdm 09:44, 7 October 2007 (UTC)

Good enough. I ended up doing this edit which I think makes a similar but much more accessible point. At the least, the first paragraph needed to say something about the physical nature of SR, is essense turning it into the lead for the lead. --EMS | Talk 16:11, 7 October 2007 (UTC)

Applications of special relativity

That section needs a bit more than merely mentioning GPS, which is an application of general relavity. At best special relativity can be used as a mere approximation for the calculation of a merely partial effect Does anyone have references for the usage of relativistic equations in the design of cathode ray tubes? I'm sure I've seen it mentioned a few times but can't remember where. I've added this to the section with a {{Fact}} tag. - DVdm 12:07, 7 October 2007 (UTC)