# Talk:Special relativity

## Rewrote

I have rewritten this page to cover the bare bones of relativity. I am considering how to "simplify" it some more. I see some big words in my explaination of the relativity of simultaneity that perhaps I can get away from. This is only a beginning, but at least it gets away from the previous presentation which did not separate the cause and the effect. -- en:user:ems57fcva 208.235.252.254 17:34, 1 November 2005 (UTC)

### More changes

I have added some math to what I did. I have also done my best to keep this prety much simple while adding enough math to give people a sense of what this is all about. Be advised that I may be up against the limits of what can be covered with simple english! However, I do hope that I have done a good job of encapsulating what relativity is about. --Ems57fcva 02:39, 2 November 2005 (UTC)

## Merger

Transwiki:Special relativity for beginners is now available for merger into this article. Uncle G 10:33, 18 November 2005 (UTC)

## "moving clock, moving rod?"

I'm not too sure about it, but I remember my physics teacher saying it has to be "ACCELERATING".

(or relative moving..?) --203.214.59.174 11:24, 20 November 2005 (UTC)

naw, that's not true...accelerating would be under general relativity. The whole premise of special relativity is that if one cannot tell the difference between moving at a constant velocity and not moving at all. 68.79.203.191 16:11, 29 May 2006 (UTC)

## Simple Template

I just went ahead and added the Simple template to the top of the article, because I think some real work could go into simplifying the language here. It's a great article, and I'm well aware that the subject matter requires some complexity and depth, but right from the first sentence of the summary, I think we're using bigger words than we need. I'll be back, of course, but I thought I'd start the process by adding the template. MBlume 12:41, 16 May 2006 (UTC)

I agree - and I didn't even see your template header before I read the article.

This article reads as a summary, rather than a simplification. A poor summary, at that...

## Forget the equations

To me it looks like it could be alot simpler if we just got rid of the equations and just right E=mc^2 to the same effect. Geeksluvpi 23:34, 8 October 2006 (UTC)

E=mc^2 isn't the most important part of special relativity. That's just an add-on. However, I agree that the Lorentz equations are either not explained well or are too complex. Maybe explain the terms more simply and then say "This equation describes how much slower time goes and how much shorter lengths become."--204.10.221.32 (talk) 16:34, 9 March 2009 (UTC)

Hi. I recently had to give a presentation to a classful of 15 yr olds on this topic, and I found a (very famous) thought experiment (described at http://plus.maths.org/issue36/features/aiden/) to be very useful in explaining the concept of time dilation without resorting to maths. The Lorentz transformations *are* important, however, so I feel they should at least be mentioned, if not explained. Drivas (talk) 14:42, 31 July 2009 (UTC)

## Lorentz Transformations

I would like to rewrite this section, with less of an emphasis on explaining coordinate systems, and more of an approach based on simple concepts backed up by extensive, but step by step math. If we assume the reader knows some basic algebra, it's entirely possible to have a completely comprehensive, yet simply written, article. 71.17.86.54 (talk) 05:26, 10 June 2010 (UTC)

## Misinformation

The text currently says:

Also, Einstein said that as the Earth moves through space, our measuring devices change length (ever so slightly). So, any measuring device used to measure the speed of light is off by exactly the right amount to make the starlight seem to be moving at its regular speed.

This explanation implies that there has been a kinetic change in the size of moving objects. http://en.wikipedia.org/wiki/History_of_special_relativity says:

Also Lorentz (1892b) proposed length contraction independently from Fitzgerald in order to explain the Michelson-Morley experiment. For plausibility reasons, Lorentz referred to the analogy of the contraction of electrostatic fields. However, even Lorentz admitted that that was not a necessary reason and length-contraction consequently remained an Ad hoc hypothesis....Lorentz also recognized that his theory violated the principle of action and reaction, since the aether acts on matter, but matter cannot act on the immobile aether....Einstein refused to invent auxiliary hypotheses, and draw the direct conclusions from the facts stated above: That the relativity principle is correct and the speed of light is constant in all inertial reference frames. Because of his axiomatic method, Einstein was able to derive all results of his predecessors – and in addition the formulas for the Relativistic Doppler effect and Relativistic aberration – on a few pages....

The "light clock" derivation works perfectly without making any assumptions about the shrinking of a moving clock. Patrick0Moran (talk) 23:29, 30 December 2010 (UTC)

There is a discussion in Mermin's Space and Time in Special Relativity, chapter 19, about why a moving measuring rod shrinks. However, if the light emitter and the light detector in a light clock were in line with the direction of motion, and if the idea of a "real" length (that can be shrunk) has any meaning, then the distance traveled by light in making one "tick" of the light clock ought to be shrunk as well. That's what intuition says, at least at first glance. However,
```the observers traveling with the clock do not see the shrinkage because their measuring sticks are shrunk as well, which would mean that the clock's tick would not shrink -- but, again, from their perspective. There is another wrinkle involved because the original contribution to the length the beam of light travels in a light clock from emitter to detector could be made essentially equal to half of the sum of the physical dimensions of the emitter and detector,and that distance could be measure as little as a mm or two. The total time traveled by light in a light clock is mostly dependent on the length from emitter to reflector and back to the detector in the vicinity of the emitter -- and that dimension, using a modern skyscraper, could currently be made to measure in the km. range. What contributes the most to the slowing of a light clock from an "unmoving" observer's perspective is the "moving" of the base of the clock from one place to another, and that dimension is hardly influenced by the "shrinkage" of the light clock that is "moving." The clock does not shrink enough in a helpful way to explain its slowing down.
```
If you take the logical/mathematical implications of the "moving" of a light clock and work from there, then I think that the Lorentz-Fitzgerald contraction and everything else is consistent. There are no exceptions to be explained away. Starting with a classical viewpoint and "explaining" the shrinkage of clocks by the effects of an aether on a classical physical clock resulted in anomalies or contradictions. So the shrinkage of clocks ought to be understood as a relic of a subtly flawed way of thinking about things that violated Galilean relativity, not as the underpinning for Einstein's theory. Patrick0Moran (talk) 15:22, 31 December 2010 (UTC)

## Remove the box of general theory. It is only confusing here.

I do not see why there is a box on the general theory of relativity in this article. It will only confuse people here. People with no knowledge of special relativity will deduce that they need to understand that box to understand special relativity. People may give up reading the article, not understanding what the box is doing there. The only general theory of relativity has in this context, is somewhere where it is explained why this was the next step. I vote for its removal. 80.216.136.251 User: DanielDemaret (talk) 11:52, 13 January 2014 (UTC)

• Agree. It is like putting the "South America" box into the "North America" article.Ufim (talk) 10:43, 11 September 2018 (UTC)