Moving Through Curved Spacetime
DOI: 10.1063/1.1634516
A Search and Discovery piece by Steven K. Blau (Physics Today, June 2003, page 21 ) discusses Jack Wisdom’s work showing that the position of an object can be changed when that object modifies its shape by extending and retracting across a Schwarzschild metric. Although this result may be new to theorists, it is already known to rocket scientists.
In a paper presented in 1990, I showed that by changing the length of a tether in a gravitational gradient—that is, in curved spacetime—one can modify the orbit, even to the extent of making the object climb away from the planet without expenditure of reaction mass. 1 In 1987, Manuel Martinez-Sanchez and Sarah Gavit had calculated similar results. 2 One can’t push on flat spacetime, but in a region of curved space—or, if you prefer, tidal forces—one can use the difference in force to push against gravity.
References
1. G. A. Landis, Acta Astronautica 26, 307 (1992) https://doi.org/10.1016/0094-5765(92)90076-U .
2. M. Martinez-Sanchez, S. A. Gavit, J. Guid. Control Dyn. 10, 233 (1987) https://doi.org/10.2514/3.20208 .
More about the Authors
Geoffrey A. Landis. (geoffrey.a.landis@nasa.gov) NASA Glenn Research Center, Cleveland, Ohio, US .
