Can an observer really catch up with light?

Authors: Tian G.¹; Zheng Z.²

Source: Classical and Quantum Gravity, Volume 20, Number 18, 2003 , pp. 3927-3931(5)

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Abstract:

Given a null geodesic ₀() with a point r in (p, q) conjugate to p along ₀(), up to the second variation, there will be a variation of ₀() which will give a timelike curve from p to q. This is the well-known theory proved in the famous book (Hawking S W and Ellis G F R 1973 The Large Scale Structure of Space-Time (Cambridge: Cambridge University Press)). In this paper, we prove that the timelike curves coming from the above-mentioned second variation have a proper acceleration approaching infinity as the timelike curves approach the null geodesic. This means no observer infinitesimally near the light can begin at the same point with it and finally catch up with it. Only when separated from the light path finitely, can the observer begin at the same point with it and really catch up with it.

Language: English

Document Type: Miscellaneous

Affiliations: 1: School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, People's Republic of China 2: Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China

Publication date: 2003-01-01