Talk:Special relativity/Archive 3

Removed claim of experimental verification for 2nd postulate

In the statement of the second postulate, I have removed the sentence: "This postulate has been verified experimentally." For my reasons, I will quote what I wrote on Wikipedia:Featured article candidates/Special relativity:

"In general experiments don't and can't verify theories, they can only falsify them. Repeated attempts to falsify the predictions of a theory constitute not proof of, but evidence for a theory. In the case of special relativity there is a considerable body of experimental evidence consistent with the predictions of special relativity. There might be (and some claim there are) other theories which are also consistent with this body of experimental evidence. To say that the second "postulate has been verified experimentally" is sloppy and misleading at best. It should be removed, in favor of a section titled something like "experimental evidence for special relativity". Paul August 23:00, Dec 11, 2004 (UTC)"

As I said above, someone needs to write a section on the experimental evidence in support of this theory. Paul August 15:21, Dec 15, 2004 (UTC)

     A Wee Bit of Free Advice for Anyone Who
     Wishes to Contribute to the Proposed
     SR Experimental Evidence Section

All of the results of special relativity (SR) are explicitly given via its math, aka its Lorentz transformation equations.

Since these equations cannot be derived sans the use of at least two clocks in each frame, all of SR's math (and thus all of SR itself) is dependent upon Einstein's definition of clock synchronization and its inherent lack of absolute simultaneity.

Thus, all of the results of SR are given by man, not nature, so none are laws of nature, and all of SR's two-clock results are incorrect due to the absence of absolute simultaneity.

Therefore, all of the results of SR are either circular or incorrect.

For example, its one-way light speed invariance is fully circular because it is given at the start via a mere definition from man.

For another example, its "length contraction" is an incorrect result due to the SR observer's inability to pin down (or locate) the endpoints of a passing rod absolutely simultaneously.

For yet another example, "time dilation" is an incorrect result again due to SR's lack of absolute simultaneity. (A passing clock is always compared with two of Einstein's absolutely asynchronous clocks in a given frame, with the incorrect result that the passing clock has "slowed.")

Here is a simple proof that SR does not even pertain to intrinsic or actual clock rhythms: Although a single, passing, steady-velocity atomic clock cannot possibly have more than one internal atomic rhythm, SR's observers in various frames find that the clock "runs at many different rates." (And similar proofs apply to SR's "length contraction" and its "momentum variance.")

It is not possible to experimentally test the sole basis of SR (aka the second postulate) because this postulate gives its result at the start. In other words, if one manually forces one's clocks to obtain one's prechosen one-way light speed invariance/isotropy, then of course one's clocks will obtain it. (They will also obtain the relativistic results, such as SR's "time dilation" and "length contraction.")

To top it off, SR does not physically explain the Michelson-Morley experiment (whereas Lorentz's theory does).

Cadwgan Gedrych 19:41, 15 Dec 2004 (UTC)

On the "circularity" of the second postulate

Cadwgan, quite rightly (if I understand him correctly), points out that the postulates as they are often stated (including in Einstein's 1905 paper, as well as in many textbooks) contain a certain circularity: the speed of light is postulated to be constant in all frames, but velocity is measured by times at different points in a frame, and times at different points were synchronized by Einstein by assuming that the speed of light is constant. On the other, hand, modern papers (e.g. Wolf and Gerard, above) circumvent this difficulty by rephrasing the question as one of the equivalence between Einstein's light-pulse synchronization and classical slow clock transport.

Still, it is an interesting question — it would indeed be surprising if there were a new objection to relativity on purely philosophical grounds, and in fact Cadwygan's argument turns out to be quite old. So old (nearly a century), in fact, and disposed of so long ago, that I had to spend some time in the library and look through a couple of dozen books to find any reference to it at all.

Early writers, including Einstein himself, were apparently content to state that the theory was internally consistent and leave it at that, a treatment that was carried over into a number of textbooks (though most don't even broach the subject of circularity). However, the question was apparently debated in the first half of the 20th century, and the conclusion was the same as the one I came to above: there is an implicit postulate that Einstein's light-based definition of measures of length and time at different points must be consistent with the pre-relativistic definition via slow transport of "clocks" and "rulers". This postulate can be and has been tested against experiment (such as in the Wolf and Gerard paper, above).

This resolution is discussed, for example, in a textbook by Born and another by Pauli, although the clearest discussion I found was in a ~1950 textbook by a French experimental physicist (whose name escapes me). I have a long list of interesting quotes on the subject in my office, and perhaps tomorrow I will write up a short article for Wikipedia that the present page can link to.

—Steven G. Johnson 06:33, Dec 16, 2004 (UTC)

Steven noted:

"... modern papers (e.g. Wolf and Gerard, above) circumvent this difficulty by rephrasing the question as one of the equivalence between Einstein's light-pulse synchronization and classical slow clock transport."

As I have said, rephrasing the question does not circumvent the difficulty.

Here is the relevant equation:

the 2nd postulate ≠ slow clock transport

Steven further noted:

"Still, it is an interesting question — it would indeed be surprising if there were a new objection to relativity on purely philosophical grounds, and in fact Cadwygan's argument turns out to be quite old. So old (nearly a century), in fact, and disposed of so long ago, that I had to spend some time in the library and look through a couple of dozen books to find any reference to it at all."

I have made no mere philosophical objection, and my objection was not disposed of long ago (or even yesterday).

The only way to dispose of my objection is to explicitly admit that special relativity does not call for invariance/isotropy in the case of light's one-way speed between two same-frame clocks, and that this is not given via definition prior to the "measurement," making it purely circular, trivial, and not given by nature (so it is not a law of nature).

And while you are at it, please prove that Einstein's one-way, two-clock invariance is the correct result. (I have already proved experimentally that it is not, but this simplest of experiments was simply ignored, which usually means "it is correct.")

Also ignored was my citation of the 1992 paper which proved that invariance and isotropy are not necessarily the results of the two-clock, one-way light speed measurement. Cadwgan Gedrych 16:18, 16 Dec 2004 (UTC)

Where's the proof you're referring to here? Is it the one where you incorrectly analyzed a relativistic situation using classical mechanics? --Carnildo 20:29, 16 Dec 2004 (UTC)

My simple proof that light's one-way speed varies with frame velocity was given above under the heading "Second Postulate."

I did not use classical mechanics. (I used no clocks or rulers.)

I did not analyze a relativistic situation. (I used no clocks or rulers.)

I did present a straightforward experimental proof that light's one-way speed differs for differently-moving observers.

Why not simply cite a specific inaccuracy re my presentation?

Or do you really believe that light from an approaching car's headlamps will not reach two meeting-in-passing observers absolutely differently?

Pardon me for being pushy, but the following challenge needs to be given:

............Simple Math Derivation Needed............

Even after deliberately disregarding all preceding and subsequent words in his book, the fact remains that Einstein at one point definitely derived the very simple equation w = c - v.

Here are his own words: "w is the required velocity of light with respect to the carriage, and we have w = c - v. The velocity of propagation of a ray of light relative to the carriage thus comes out smaller than c."

http://www.bartleby.com/173/7.html

All I am looking for is one brave soul who will show this derivation. Cadwgan Gedrych 21:41, 16 Dec 2004 (UTC)

No, I will not. There is no point in it, as you have demonstrated that you will not listen. If you had read that very work you cite beyond the point at which Einstein provides that equation, you would have seen Einstein show that the equation is incorrect. Likewise, if you had read what I wrote under the heading of "Second Postulate", you would have seen me pointing out the inaccuracies. I will not debate this with you any further. --Carnildo 22:00, 16 Dec 2004 (UTC)

Fine with me, dude; I figured that you would fold 'em. That Einstein believed the equation to be incorrect is irrelevant. I must now label you an intellectual coward. Sorry, but I calls 'em as I sees 'em. (And take a quick peek if you dare at my recent reply to your "wonderful" way of "pointing out the inaccuracies.") Maybe some far braver soul will step forward and show the derivation. (Lordy, like there should be no shortage of good mathematicians running loose around these here parts, not that the math is overwhelmingly difficult! ;-) ) Cadwgan Gedrych 01:44, 17 Dec 2004 (UTC)

"our work"

I removed the following sentence from the special relativity section of the Theory of relativity article: 'While developing this theory, Einstein wrote to his wife Mileva about "our work on relative motion".'

While it doesn't seem to belong there (that page seems to be just some kind of pseudo-disambig), mayhaps it should belong in this article? Intangir 20:43, 6 Jan 2005 (UTC)

We'd need to know the context for the statement to make sense. Who does "our" refer to? --Carnildo 00:11, 7 Jan 2005 (UTC)

Good question. I'm not sure, I have a geometry/history book, "Euclid's Window" which mentions that correspondence blurb. The author seems to think 'our' refers to Albert and Mileva but more or less dismisses the notion that it was really a collaborative effort of the two of them. I have no clue as to it's significance, but someone who edited Theory of relativity felt it was at least worthy of mentioning. Intangir 01:28, 7 Jan 2005 (UTC)

Simultaneity and causality --- objection

I dispute the reasoning in this part of the article. It states: "Barring some way of traveling faster than light, it is not possible , it is not possible for any matter (or information) to travel from A to C or from C to A. Thus there is no causal connection between A and C."

I agree, that, given the first postulate, it is impossible to accellerate anything with a timelike (sublight) velocity to or beyond the speed of light.

I dispute that special relativity as derived from the postulates and experimentation prohibits the existance of particles moving faster than light.

Think of this: an electron positron pair annihilates and produces photons moving at the speed of light. This is not accelleration as we use to think of, but as a result, the system suddenly moves at the speed of light not violating relativity. (Don't mind that, by momentum conservation, the photons will be flying in different directions. Some mirrors can help there.) No law of nature or science can hinder those photons to create an new electron-positron pair by pair production.

As to my knowledge, nothing is known wether or not similar processes could create spacelike particles instead of timelike ones.

The statement that "Thus there is no causal connection ..." is not backed by the theory.

If, to the reverse, the additional assumption of the causality principle is assumed, the impossibility of things moving faster than light can be deduced.

217.81.158.237 18:07, 9 Jan 2005 (UTC)

Well, you're right that relativity doesn't prohibit FTL, but that sentence starts off, "Barring some way of traveling faster than light, ", so the conclusion follows. A fairly common way of putting it is, "Relativity, (unrestricted) FTL, Causality; choose two."

Anyway, that section is trying to contrast the timelike interval AB with the spacelike interval AC, so bringing in FTL would just get in the way.

—wwoods 19:15, 9 Jan 2005 (UTC)

As to my understanding, FTL is exactly the same as spacelike. Could you elucidate on that point?

217.81.157.237 19:39, 10 Jan 2005 (UTC)

Maybe I am mistaken, but don't physicists talk about particles that travel FTL? I know that I have heard of tachyons. If they do, though, they will have imaginary mass and length and time will flow to them in an imaginary direction. This means that they will be impossible to detect and according to some physicists, that means that they don't exist. Some physicists have said that space and time are at right angle to each other which implies that time is imaginary space and vice versa. I might even be so rash as to define a second as such:

$1sec=i*300,000,000m$

That's besides the point, though. You could say that a tachyon moves through three time dimensions and one space because of that. Sabejias

"Dynamic Universe"

• Dynamic Universe (DU) - a highly promising new model of the universe developed by Dr. Tuomo Suntola

I removed this link from the article. From what I can find on the web, it is a replacement for GR that is based around the concepts of absolute space and absolute time. As far as I can tell, very few people take it seriously, as it hasn't yet been verified that it explains everything GR does, much less make new, testable predictions (in particular, one back-of-the-envelope calculation shows it getting the orbit of Mercury wrong; another says that it doesn't handle the orbital decay of binary pulsars). --Carnildo 00:41, 4 Feb 2005 (UTC)

Special Relativity for Beginners

The Special Relativity page is excellent. However, would you be in favour of a page called Relativity for Beginners that treats the subject at a simpler level? The subject has (at least) three levels of treatment: beginners, undergraduate, graduate. The maths and reasoning in the current article is junior undergraduate level or senior school maths/physics specialist level. A beginners text might be linked as such from the current main text. Loxley 20:32, 7 Mar 2005 (UTC)

• Certainly something has to do about the sprawl of the current article. I was already thinking of moving the more technical sections "mathematical formulation of the postulates" and "compatibility with other theories", which I have worked primarily on, to a new page, linked from here of course... perhaps in a week or so if there are no objections. This doesn't directly address your issue but it may help focus the current article. Terry 22:22, 7 Mar 2005 (UTC)

Anti-gravity?

Does the effect of relativistic mass leave any room for the possibility of negating gravitational fields? That is, if one could get electrons or other particles (obviuosly a lot of these particles) orbiting at relativistic speeds around an object, would any of the surrounding matter experiance a less powerful gravitational force from the earth's field, making them lighter?

Absolute rest

Special relativity takes into account the fact that nothing can be accelerated to the speed of light in a vacuum. Does it also take into account the fact that nothing can be deccelerated to absolute rest in a vacuum?

GoldenBoar 21:36, 7 January 2006 (UTC)

There is nothing in special relativity that prevents an object from being at rest (in fact, in some reference frame, any given object will be at rest). It's the Heisenberg uncertainty principle that prevents you from simultaneously knowing both the position and momentum of an object (meaning that if you know an object is at rest, or any other specific velocity, relative to you, you have no idea where it is). That's an aspect of quantum mechanics, not special relativity.

What special relativity does is state that light always appears to travel at C no matter what the relative velocities of the emitter and the observer, and works through consequences of that axiom (which ends up giving time dilation, mass gain, and length contraction for relative velocities approaching C, and the C speed limit). --Christopher Thomas 22:55, 7 January 2006 (UTC)

According to the article, absolute zero, the laws of thermodynamics show that absolute zero can never be achieved. If this is true, wouldn't that invalidate the concept of rest energy?

GoldenBoar 23:29, 7 January 2006 (UTC)

Temperature is only defined for a collection of particles. A single particle can appear to have any velocity you please, depending on what frame you choose to look at it from. Furthermore, because the kinetic energy invested in temperature has a known, very simple, relation, you can easily calculate what the mass at zero temperature would be for a collection of particles from measurements of its mass at nonzero temperatures. In practice, there are sources of error for non-ideal solids and gases, but these aren't related to the argument you're referring to. --Christopher Thomas 00:52, 8 January 2006 (UTC)

nitpicking

at end of "Motivation for the theory..." "SR can correctly predict the behaviour of accelerating bodies in the presence of a constant or zero gravitational field" --- isn't saying "or zero" redundant? Luke Stodola 22:03, 14 Mar 2005 (UTC)

Is there anything physical moving in space-time?

This has more to do with general relativity but how can anything physical move in space-time? The conclusion is that the definitions of space and time and the equation of velocity $v=dx/dt$ forbids anything physical to move in spacetime[1]

Also there is no mathematical difference between the thing that we call 'spacetime' and the other thing that we call the gravitational field. -- Orionix 11:49, 17 Mar 2005 (UTC)

That site was done by someone who doesn't understand the basics of dimensional analysis. A time velocity component of 1 second per second is perfectly valid, and yes, it does look like a dimensionless constant on paper, as it is just as valid to specify it as one fortnight per fortnight. --Carnildo 18:52, 17 Mar 2005 (UTC)

True true. There is time in space-time. One way to look at it: in a time-relative minowski space (i.e. one with the the time origin (t=0) at the current time), as the current time changes at a constant rate, the points are consistently shifted "down" (or up, however the space is orientated) in the t direction, at a constant rate. In any case, that basic minkoski space, as I understand, represents the state of the system, from the pov of the local reference frame.

All bodies in space-time (minkowski space) have inertia. I.e. they "move", but they do not change energy levels; they conserve speed (velocity). Were a body to accelerate (it's energy level thus changing), a force would ipso facto be involved, and we would be discussing a bending of space. That's where things like general relativity would come into play. Kevin Baas^talk 19:02, 2005 Mar 17 (UTC)

HUH? Once again, in Eng, for the non-physicists? :) Trekphiler 13:55, 2 December 2005 (UTC)

NPOV problem

For the past 15 years the problems with both Special Relativity Theory (SRT) and General Relativity Theory (GRT) have been discussed in the Journal Galilean Electrodynamics ISSN 1047-4811 published by Space Time Analysis, Ltd. This contradicts the article sentence "However, at macroscopic scales and in the absence of strong gravitational fields, special relativity is now universally accepted by the physics community and experimental results which appear to contradict it are widely believed to be due to unreproducible experimental error.". In fact the the above journal was created to counteract the suppression of any questioning of Relativity.

There are much bigger concerns with NPOV, for example the corrections I made half a year ago to the biased POV about mass definitons have been vandalised and replaced by the same biased POV. Worse, misconceptions about the theory of Newton that I corrected and extended have been deleted and partly replaced by misinformation.

In the near future I'll reinsert the corrections, with some explanations and references on this page to the ignorant as well as to bystanders (isn't Wikipedia meant to REDUCE ignorance?!). Harald88 22:00, 10 October 2005 (UTC)

In the March/April 2005 issue of Galilean Electrodynamics page 23 is an article titled "First-Order Fiber-Interferometric Experiments for Crucial Test of Light-Speed Constancy". This article covers the experimental design requirements to test some of the features of relativity. The last sentence at the bottom of page 23 is "Therefore, the assertion that light speed is still c in a system moving translationally relative to Earth has not yet been verified.". Relativity is a theory that has not been adequately tested. The last three sentences in the above article are "Here, we challenge the relativistic physicists: please don't try to make the light-speed constancy un-definable. If you care to define that the speed of light is the same for any moving observer, we will design a GPS experiment to show it is not the truth. Give us a clear definition, and we will disprove it.".

Also "Special Relativity Theory (SRT)" not "special theory of relativity" is standard in the above article and journal. Twice when I changed it in the Wikipedia article, it has been put back. I guess it's whatever people want but it's not what people who are discussing the issues are using.

I have trouble consiering any journal to be "mainstream" or even "serious challenge to orthodoxy" when the journal website's address is "mywebpages.comcast.net". It shows they're not putting a lot of effort into being taken seriously. --Carnildo 05:00, 18 Mar 2005 (UTC)

Therefore, the assertion that light speed is still c in a system moving translationally relative to Earth has not yet been verified. Indeed?

I misread the claim somewhat. I guess the authors want a time measurement to be conducted on board a spaceship somewhere. Probably they believe in some variation of the old "Ether drag" hypothesis. I concede that such a measurement would be nice to have and I'm not aware that this has been performed yet, but I hasten to add that the results of the "cosmological source" experiments would be very hard to explain if the speed of light wasn't constant (in Earth's reference frame) over the entire journey. Aragorn2 19:34, 27 February 2006 (UTC)

The articles on Galilean Electrodynamics and Petr Beckmann are quite interesting, too. Seems like Beckmann et al had trouble getting their theses through peer review and into well-known scientific publications, that's why they started their own fringe journal. This inability is, of course, owed to the Vast Relativistic Conspiracy, and not due to the disinformation they seem eager to spread (see above). The mention of GPS is just hilarious. The entire functioning of GPS is based on relativity, and I seriously doubt that a theory that doesn't provide a model that closely approximates reality would have been sufficient in this undertaking. It's also safe to say that the evidence for SRT is a lot more solid that that for Newtonian (Galilean) physics.

Notwithstanding the above rant, I grant them the possibility of having a point somewhere, and don't want to discount their works as "unscientific" all too easily, so the word "almost" could be inserted between "now" and "universally". Aragorn2 18:59, 27 February 2006 (UTC)

I was curious as I didn't know Galilean Electrodynamics had a web site. In the 15 years that I've read it, I have never seen a web site mentioned. I carefully looked through the last two issues but no mention of a web site. So I did what you apparently did, I put Galilean Electrodynamics into Google and got the site you refer to. I looked through it and the best I could determine is that it is a personal web site of one of the editors as it contained an email address for authors to use for submissions. Anyway, thank you for the web site address. I used it as an external link in a Wikipedia article I created on Galilean Electrodynamics as the Wikipedia article on the founder Petr Beckmann mentioned it. While I was on Google, I scanned down the hits and noticed Symmetry or Simultaneity by Ronald R. Hatch a contributer to Galilean Electrodynamics. If you are interested his credentials are at credentials.

While on the topic of google, "Special theory of relativity" gets 84,000 google hits [2], whereas "Special relativity theory" gets 9,650 [3]. I'd say it's no contest, at least as far as contemporary usage is concerned. Terry 06:57, 20 Mar 2005 (UTC)

Archive created

I took the liberty of moving all talk from before this month to an archive, see Talk:Special_relativity/Archive1. It seemed things were getting a little bloated around here. Terry 06:57, 20 Mar 2005 (UTC)

• Also, I realized that there are a lot of SR pages floating around WP which are not really linked well to here (or to the Special relativity category). I am doing a bit of clean-up and linking, please excuse the flurry of minor edits. :-) Terry 05:14, 21 Mar 2005 (UTC)

• • OK, done with all that. Terry 07:10, 21 Mar 2005 (UTC)

Alternatives to SR

In the interests of NPOV and all, and given all the previous discussion on this talk page, I have opened up a section on alternatives to special relativity at Status_of_special_relativity#Alternatives_to_special_relativity. As you see it is extremely rudimentary at present, but perhaps some people here would have an interest in expanding it. I might also suggest that discussion of these theories (or anything else relating to the theoretical, experimental, or cultural status of special relativity) be sent to Talk:Status_of_special_relativity. Terry 07:10, 21 Mar 2005 (UTC)

Motivation section

I almost reverted the unexplained section blanking myself until I reread that section and decided that it wasn't currently adding anything to the article. I think that jumping to the postulates is a more appropriate way to organize it now, as the Motivation section, which is trying to put everything into historical perspective, is rather confusing the issue.

I think that in this instance, walking the reader through the many wrong turns physics has taken is not the best way to introduce a layperson to an already confusing and misunderstood field. I would vote for that section to be removed or moved to a later History section.--Laura Scudder | Talk 22:53, 20 Apr 2005 (UTC)

• I can see your point. Perhaps we can give a very short version of the history and motivation in this page, and spin off the longer discussion into a separate page, e.g. History of special relativity? That would be consistent with the way the rest of this page is organized, and help cut down the perennial problem of page bloat that we seem to have here. Terry 20:57, 21 Apr 2005 (UTC).

I think that's a very good idea. There's plenty of material that could go into a History of special relativity page that would just be bloat if put here. -- Fropuff 22:27, 2005 Apr 21 (UTC)

Well, I've spun things off, and left an abridged version on the main page. It's not the most ideal solution, but the best I can do on short notice. Presumably some further polishing is needed. Terry 17:18, 24 Apr 2005 (UTC)

I now read this, and I (blush) simply had not noticed that there was such a page - and obviously this is true for many! Somehow the reader is not really made attentive to the fact that there is an other article, despite the (too subtle) link at the start. OK next time maybe I or someone else can merge everything that has appeared here with the history page (plus a more visible pointer), and then the main article will go straight to the postulates. Harald88 19:28, 23 October 2005 (UTC)

• For trivia wanks (c'est moi?), the paper in which SRT was first publ was "On the Electrodynamics of Moving Bodies" (1905). Trekphiler 14:01, 2 December 2005 (UTC)

Quantum Physicists are just catching up with Relativity!

I understand quantum mechanics just enough, not to make any great discoveries in the field, but enough to understand the basics. Special Relativity is the same way. I found something interesting though, relativity implies both wave-particle duality and supersymmetry! A wave is a carrier of eneergy from place to place. A paritcle can be viewed as a carrier of mass from place to place. Relativity says energy is the fourth-dimensional extendsion of momentum (which is mass times velosity). This implies that waves are fourth-dimensional extendsion of particles! This also implies that the carriers of energy (Bosons) are extendsions of the carriers of mass (Fermions)! Wave-particle duality and supersymmetry. It seems so simple I'm surprized that this was overlooked for so many years.--SurrealWarrior 18:36, 20 Jun 2005 (UTC)

Quantum physics and special relativity were merged with a solid theoretical basis in 1928, by the Dirac equation. So I wouldn't say it was overlooked. One doesn't imply the other though. -- Tim Starling 02:14, Jun 21, 2005 (UTC)

Given mass-energy equivalence, doesn't that imply bosons are fermions? (Just call me Montgomery Scotch...) Trekphiler 14:07, 2 December 2005 (UTC)

No. Bosons and fermions differ because of the difference in spin; this results in different parity wavefunctions which results in different behaviour when positions are exchanged. Masud 21:23, 18 December 2005 (UTC)

Och, aye. Excuse me while I go change Planck's constant. =] Trekphiler 22:23, 18 December 2005 (UTC)

missing word(s)?

Seems to be something missing here:

The laws of physics are independent of location space or time.

Should it be, "...independent of location in space or time."? Or is punctuation needed? Otherwise, it sounds like we're discussing "location space," a phrase I don't understand. DavidH 1 July 2005 01:35 (UTC)

I think you're right, it's missing an in. --Laura Scudder | Talk 1 July 2005 02:01 (UTC)

Thanks Laura. I'm reluctant to make a change in a topic so out of my field. Anybody else want to weigh in before I make the change?

DavidH 1 July 2005 02:15 (UTC)

Ladder Paradox

Will anyone who understands special relativity please help us in our discussion of the Ladder paradox. We are going around and around in circles and maybe another viewpoint would help. Please don't muddy things - If you don't understand Minkowski diagrams its probably not a good idea, but if you do, we need your help. Thanks PAR 1 July 2005 03:44 (UTC)