Coordinate time and proper time in the GPS

T. Matolcsi, M. Matolcsi

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The global positioning system (GPS) provides an excellent educational example of how the theory of general relativity is put into practice and becomes part of our everyday life. This paper gives a short and instructive derivation of an important formula used in the GPS, and is aimed at graduate students and general physicists. The theoretical background of the GPS (see [1]) uses the Schwarzschild spacetime to deduce the approximate formula, , for the relation between the proper time rate s of a satellite clock and the coordinate time rate t. Here V is the gravitational potential at the position of the satellite and is its velocity (with light-speed being normalized as c = 1). In this paper we give a different derivation of this formula, without using approximations, to arrive at , where is the normal vector pointing outwards from the centre of Earth to the satellite. In particular, if the satellite moves along a circular orbit then the formula simplifies to . We emphasize that this derivation is useful mainly for educational purposes, as the approximation above is already satisfactory in practice.

Original languageEnglish
Pages (from-to)1147-1151
Number of pages5
JournalEuropean Journal of Physics
Volume29
Issue number6
DOIs
Publication statusPublished - 2008

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Global Positioning System
derivation
light speed
circular orbits
approximation
students
gravitational fields
clocks
relativity

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Coordinate time and proper time in the GPS. / Matolcsi, T.; Matolcsi, M.

In: European Journal of Physics, Vol. 29, No. 6, 2008, p. 1147-1151.

Research output: Contribution to journalArticle

Matolcsi, T. ; Matolcsi, M. / Coordinate time and proper time in the GPS. In: European Journal of Physics. 2008 ; Vol. 29, No. 6. pp. 1147-1151.
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