Relativistic twins or sextuplets?

Abstract

A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back.

The relativistic rocket

“…According to the clock hypothesis [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] (see also Marder [39, pp 89-98]), the rate dτ of local time, as measured by a stationary clock in the momentarily commoving inertial frame K(τ ), is equal to the rate dτ * of the local time as measured by a stationary clock in the accelerating frame K * (dτ * = dτ ). That is, the time rate depends only on velocity and not on acceleration (see also Adler et al [40, p 115]).…”

A relativistic rotating frame with physics majors, photons and mirrors: causality lost

“…Condition (B) implies that 'coordinate clocks' and 'standard clocks' will be identical [9]. In most cases involving accelerated motion, even uniform acceleration, these clocks do not agree, but the case of constant angular velocity is a special case [10]. Condition (C) means that photons taking 'short cuts' along chords of the cylinder are not to be used in the clocks.…”