Talk:Special Relativity/Introduction

Light velocity in aether
It is stated that the observed velocity of light is the sum of the velocity of the light relative to the aether and the observer's velocity relative to the aether.

Would basic consideration of these two vectors not indicate that it is in fact the difference?

This is better. RobinH 10:47, 17 July 2006 (UTC)

Correct Isimangaliso Mohapi (discuss • contribs) 15:06, 25 June 2020 (UTC)

Better?
Hi RobinH, Perhaps next time you might like to discuss before you totally delete and rewrite an article next time. I had some understanding when I read this current (reverted) version, but I was totally lost by your rewrite about who proposed and theorised the concept of special relativity. Please discuss this, maybe I am wrong, please tell me so. I'm sure we are supposed to discuss major edits first, aren't we?--Read-write-services 22:32, 7 November 2006 (UTC)


 * Please accept my apologies. The problem with the existing introduction is that it does not embrace the scope of Special Relativity. Newtonian physics begins with a discussion of velocity and acceleration but no one would say that Newtonian physics is about relative velocities - it extends to force, energy and thermodynamics. Similarly, relativity begins by reconsidering the basis of Newtonian physics but it is actually a theory that entirely replaces everything that Newton and pre-relativistic physics had derived. The idea that modern physics is just a tweak of nineteenth century physics misses the entire point, modern physics is a total replacement for what went before.  Modern physics is deeply shocking, it proposes that the universe is a four dimensional manifold containing probability waves. Newtonian physics proposes that the world is a three dimensional manifold of no duration containing lumps.


 * Special relativity has a different ontology from Newtonian physics. Length contraction is due to the differing slices of the worldtube of an object that are observed by observers in relative motion, quantum physics originates in de Broglie waves which are due to the relativity of simultaneity, time dilation is due to the time gaps that result from four dimensional space-time etc. etc.. RobinH 12:54, 13 November 2006 (UTC)


 * This intro needs to say that SR is not just a tweak to the physics that went before. It also needs to point out that SR is not solely Einstein's work. Einstein got his nobel prize for photoelectric emission, people knew that Minkowski, Poincare, Lorentz etc. had all been involved in SR. 86.14.2.37 13:08, 13 November 2006 (UTC)

Hi, I didn't mean to upset you, I'm having problems just trying to understand it all. I thought I knew something about physics-until I came upon this. I consider myself reasonably educated. I edit, proofread and write articles for the general public, the photographic community and I have taught Medical Imaging, Radar, Communications electronics as well as aviation navigational aids. perhaps it may be presumtuous of me, however, if I cant understand it, (I think you lost me at four dimensional manifold containing probability waves.) then I think that a layperson reading it would be "blown-away". I certainly take your point about getting the facts right-for sure! Maybe we need to consider the potential audience that this is aimed at? anyway, thank you for your reply. Cheers!--Read-write-services 21:53, 13 November 2006 (UTC)


 * I agree that the introductory version of this text should be accessible to the layperson. However, it is incredibly important that we do not compromise the integrity of the theory.  Relativity is not just a clever way of calculating velocities.


 * The key difference between relativity and Newtonian physics is that Newtonian physics assumes that euclidean geometry, including the fifth postulate, describes the world. This difference is expressed in the laws of physics. The laws of physics are statements about the symmetries and corresponding invariants that exist in nature.


 * In a three dimensional euclidean space the conservation laws are conservation of momentum, conservation of angular momentum and conservation of energy. In space-time the conservation law that is of prime importance is conservation of four momentum which contains energy and momentum conservation in a single concept.


 * In a thoroughly modern treatment (not for laypersons) we would introduce noether invariants and the generalised concept of a "physical law" then point out that the observed world corresponds to a 4 dimensional manifold of signature (---+). This is an entirely different entity from a 3 dimensional manifold of signature (+++). For instance, the 4 D manifold contains the possibility of quantum physics (See: de Broglie, L. (1925) On the theory of quanta. A translation of : RECHERCHES SUR LA THEORIE DES QUANTA (Ann. de Phys., 10e s´erie, t. III (Janvier-F ´evrier 1925).by: A. F. Kracklauer. http://www.ensmp.fr/aflb/LDB-oeuvres/De_Broglie_Kracklauer.pdf ). It is also not generally appreciated that the schrodinger equation was almost immediately replaced by the Dirac Equation which is Lorentz invariant, introducing the relativistic 4 momentum and hence predicting quantum spin (See [Dirac equation http://en.wikipedia.org/wiki/Dirac_equation]).


 * It is a diabolical tragedy that popular science articles often describe QM and relativity as if they are alternative theories. QM is a prediction of SR and a logical consequence of the signature of spacetime.


 * Somehow we have got to transmit to the lay reader that relativity is a huge idea, it is not just a tweak to Newtonian physics. RobinH 17:41, 17 November 2006 (UTC)


 * I have tried to merge some of my approach with yours. RobinH 12:34, 19 November 2006 (UTC)

SP Relativity
speaking of einstein's development of SR; i believe his wife or wife to-be at that time (not sure) had a great deal to do with the r&d of this and many of the genius's credited publications and awards. Her contributions went without barely a peep towards her co-development of einsteins lifetime of great works. i do not often hear much of her regarding the contributions she made and am not entirely sure exactly how much she actually did, but i suspect given the time and the man, her assistance would barely rate a mention by the egomaniacs on top of the physics world during this rapid theoretical development period.

any comments

"same speed as the bus" is incorrect
From the introduction, "Bob, seeing the dog on the street move by, determines that the dog is moving at the same speed as the bus. Jim on the other hand, determines that the dog is not"

This seems inconsistent. Since Bob is ON the bus, Bob doesn't see that the bus is moving at all. But he does see the dog as moving. Thus, to say that Bob determines that the dog is moving at the "same speed as the bus" is incorrect. In a book like this, the distinction is important, obviously. Inconsistencies cause confusion.

Can't handle accelerating frames?
The first paragraph in the section "What's so Special?" is thoroughly incorrect: special relativity and newtonian mechanics can both handle accelerating frames of reference (and even rotating ones) perfectly fine; what makes special relativity "special" is that the principle of special relativity is restricted to inertial frames. --Marzojr (talk) 21:20, 5 May 2008 (UTC)

The text has now been amended RobinH (talk) 19:49, 16 November 2010 (UTC)