Some Remarks on a New Exotic Spacetime for Time Travel by Free Fall

  • Davide FermiEmail author
Part of the Tutorials, Schools, and Workshops in the Mathematical Sciences book series (TSWMS)


This work is essentially a review of a new spacetime model with closed causal curves, recently presented in another paper. The spacetime at issue is topologically trivial, free of curvature singularities, and even time and space orientable. Besides summarizing previous results on causal geodesics, tidal accelerations, and violations of the energy conditions, here redshift/blueshift effects and the Hawking–Ellis classification of the stress–energy tensor are examined.


General relativity Closed causal curves Time machines Energy conditions Hawking–Ellis classification 

Mathematics Subject Classification (2000)

Primary 83C99; Secondary 83-06 



I wish to thank Livio Pizzocchero for valuable comments and suggestions. This work was supported by: INdAM, Gruppo Nazionale per la Fisica Matematica; “Progetto Giovani GNFM 2017 - Dinamica quasi classica per il modello di polarone” fostered by GNFM-INdAM; INFN, Istituto Nazionale di Fisica Nucleare.


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Dipartimento di MatematicaUniversità degli Studi di MilanoMilanoItaly
  2. 2.Istituto Nazionale di Fisica NucleareSezione di MilanoItaly

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