Eur. Phys. J. Plus (2014) 129: 240
https://doi.org/10.1140/epjp/i2014-14240-x

Regular Article

Newton’s third law in the framework of special relativity

¹ Atidron Ltd., San Martin 15, 52237, Ramat Gan, Israel
² Ariel University, Kiriat Hamata POB 3, 40700, Ariel, Israel
³ Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, CB3 0EH, Cambridge, UK

^* e-mail: asya@ariel.ac.il

Received: 5 May 2014
Revised: 28 September 2014
Accepted: 2 October 2014
Published online: 11 November 2014

Abstract

Newton’s third law states that any action is countered by a reaction of equal magnitude but opposite direction. The total force in a system not affected by external forces is thus zero. However, according to the principles of relativity a signal cannot propagate at speeds exceeding the speed of light. Hence the action cannot be generated at the same time with the reaction due to the relativity of simultaneity, thus the total force cannot be null at a given time. The following analysis provides for a better understanding of the ways natural laws would behave within the framework of Special Relativity, and on how this understanding may be used for practical purposes. It should be emphasized that although momentum can be created in the material part of the system as described in the following work momentum cannot be created in the physical system, hence for any momentum that is acquired by matter an opposite momentum is attributed to the electromagnetic field.