The correct general form of relativistic transformation equations for the three-vector force is derived without using four-vectors, via the relativistic Newton's second law. The four-vector approach to the problem is also presented. The derivations extend or rectify previous derivations.

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Derivations of Relativistic Force Transformation Equations

An attempt is made to remedy confusing treatments of some basic relativistic concepts and results in recent papers by Franklin (2010 {\it Eur. J. Phys.} {\bf 31} 291-8) and by McGlynn and van Kampen (2008 {\it Eur. J. Phys.} {\bf 29} N63-N67). The authors' misconceptions are recurrent points in the literature.

Relativistic length agony continued

The twin paradox and the hafele and keating experiment

We point out a logical possibility, based on special relativity, that the validity of Einstein's 1905 generalization, Δm = ΔErest/c2, might depend on how the energy of a body is defined in special relativity. The analysis is another illustration of the importance of Ockham's razor in special relativity.

Does Δm = ΔErest/c2?

We made an attempt to remedy recent confusing treatments of some basic
 relativistic concepts and results. Following the argument presented in an
 earlier paper (Redžic 2008b), we discussed the misconceptions that are
 recurrent points in the literature devoted to teaching relativity such as:
 there is no change in the object in Special Relativity, illusory character of
 relativistic length contraction, stresses and strains induced by Lorentz
 contraction, and related issues. We gave several examples of the traps of
 everyday language that lurk in Special Relativity. To remove a possible
 conceptual and terminological muddle, we made a distinction between the
 relativistic length reduction and relativistic FitzGerald-Lorentz
 contraction, corresponding to a passive and an active aspect of length
 contraction, respectively; we pointed out that both aspects have fundamental
 dynamical contents. As an illustration of our considerations, we discussed
 briefly the Dewan-Beran-Bell spaceship paradox and the ‘pole in a barn’
 paradox.

/pdf/relativistic-length-agony-continued-3qz431lvze.pdf

Relativistic Length Agony Continued

The ether just fades away

The author presents a framework for specifying and comparing different versions of the calculation of the ex-post “contribution to a return” financial performance measure for each of three levels of application. Employing this framework, the author analyzes a conceptually complete set of versions within each level in order to determine which version best coherently captures the intuitive intent in applying the measure at that level. Specifically, the three levels that the author will explicate are the ex-post contribution of 1) the return of a component of a portfolio on a day to the portfolio’s total return for that day, 2) the total return of a portfolio on a day to a portfolio’s total return for a multi-day period, and 3) the return of a component of a portfolio on a day to a portfolio’s total return for a multi-day period. 

Andre Mirabelli

Papers

The ether just fades away

Various Ex-Post Financial Contributions to a Return and the Different Questions They Address