The necessity of the second postulate in special relativity

Abstract

Constancy of the speed of light Second postulate Electromagnetism a b s t r a c t Many authors noted that the principle of relativity together with space-time homogeneity and isotropy restricts the form of the coordinate transformations from one inertial frame to another to being Lorentzlike. The equations contain a free parameter, k (equal to c À 2 in special relativity), whose value is claimed to be merely an empirical matter, so that special relativity does not need the postulate of constancy of the speed of light. I analyze this claim and argue that the distinction between the cases k ¼ 0 and k a 0 is on the level of a postulate and that until we assume one or the other, we have an incomplete structure that leaves many fundamental questions undecided, including basic prerequisites of experimentation. I examine an analogous case in which isotropy is the postulate dropped and use it to illustrate the problem. Finally I analyze two attempts by Sfarti, and Behera and Mukhopadhyay to derive the constancy of the speed of light from the principle of relativity. I show that these attempts make hidden assumptions that are equivalent to the second postulate.

Integrasi Materi Pendidikan Agama Islam Terhadap Ilmu-Ilmu Rasional Di Sekolah Menengah Pertama

“…selama ini mata pelajaran agama diajarkan secara terpisah dan hanya ilmu umum saja 38 . Nilai-nilai Islami diintegrasikan ke dalam pembelajaran IPA adalah nilai-nilai yang bersumber dari Al-Qur'an dan hadits.…”

The Function of the Second Postulate in Special Relativity

“…Conversely, the assumption that the speed of light possesses this systemic isotropy is not in itself enough to guarantee that the transformations themselves will exhibit nomological isotropy. Indeed, I previously obtained anisotropic transformations that nevertheless embody the isotropic propagation of light signals (Drory, 2015). These transformations are not nomologically isotropic, but light propagation remains systemically isotropic under them.…”

“…1 From postulates P1-P3 alone, one can then derive what I shall term "generalized Lorentz transformations", to distinguish them from the standard Lorentz transformations, which contain the speed of light. These are (for the derivation see, e.g., Lévy-Leblond, 1976;Drory, 2015):…”

“…In a previous work I have argued that as a physical theory, special relativity must be explicitly distinguished from Newtonian mechanics, since these two theories imply different ontologies, different procedures for reproducing experiments, etc... (Drory, 2015). This means that the cases k = 0 and k = 0 represent two different theories, each distinguished from the other by an additional postulate regarding the value of k. While that value must of course be determined empirically, the distinction between the vanishing and non-vanishing cases is so fundamental that it must be included among the postulates of the theory before we can speak of the resulting structure as a well defined physical theory at all.…”

Time isotropy, Lorentz transformation and inertial frames

“…Actually, these assumptions give two possible kinematics viz. the Galilean transformation (GT) and the Lorentz transformation (LT) [3]. From LT we know that a space coordinate and time mix symmetrically.…”