Of interest is how the forward and aft starfields appear to starship crews who visually monitor their flight progress using either electronic visual displays or windows during faster-than-light flight (FTL) or while traversing a wormhole. Ford and Roman [1] and Clark et al. [2] show that for a warp drive starship at FTL speed, the angular deflection and redshift of photons propagating through the distortion of the warp bubble is such that stars in the forward and reverse hemispheres will appear closer to the direction of motion than they would to an observer at rest. The stars in the forward direction will be strongly blueshifted and in the aft direction they will be strongly redshifted. The light from stars directly overhead, underneath or to the sides remains unaffected by the aberration (see Figure 1). This aberration is qualitatively similar to that caused by Special Relativity for the case of relativistic rockets [3-5]. This suggests that visual guide/reference stars and typical star maps will be useless for warp drive starship navigation. Real-time electronic visual displays will be required to display accurate virtual starfields and maps, and they must have computer algorithms that perform real-time adjustments to account for the effects of FTL aberration in order to display visually meaningful views and maps.
Figure 1. Forward and Aft Window Views Onboard Warp Drive Starship (from Reference 1).
The view through a traversable wormhole is even worse. The negative energy density threading a wormhole throat generates repulsive gravity, which will then deflect light rays going through and around it. The entrance to the (spherically symmetric) wormhole would look like a sphere that contained the mirror image of a whole other universe or remote region within our universe, incredibly shrunken and distorted (see Figure 2) [6]. This is a topological inversion of images manifested in spherically symmetric wormhole geometry. If one were to travel through the wormhole and look back at it from the other side, then they would see a sphere (the entry way back home) that seemed to contain their whole original universe or their home region of space near Earth (within your universe). This would look just like a glass Christmas tree ornament, which is just a spherical mirror that reflects, in principle, the entire universe around it. Beams of light traveling inside the traversable wormhole throat would appear to be grossly distorted (see Figure 3). A flat-face traversable wormhole would not distort the image of the remote space region or other universe seen through it because the negative energy density at the throat is zero as seen and felt by light and matter passing through it (see Figure 4) [6].
Figure 2. A distorted, inverted view of a distant region in the universe as seen through a spherically symmetric traversable wormhole orbiting a star.
Figure 3. Distorted beams of light traveling through a spherically symmetric traversable wormhole throat.
Figure 4. The undistorted view through a flat-face traversable wormhole.
References:
- Ford, L. H., and Roman, T. A., “Negative Energy, Wormholes and Warp Drive,” Scientific American, Vol. 13, 2003, pp. 84-91.
- Clark, C., Hiscock, W. A., and Larson, S. L., “Null geodesics in the Alcubierre warp drive spacetime: the view from the bridge,” Class. Quant. Grav., Vol. 16, 1999, pp. 3965-3972.
- McKinley, J. M., and Doherty, P., “In search of the ‘starbow’: The appearance of the starfield from a relativistic spaceship,” Am. J. Phys., Vol. 47, 1979, pp. 309-316.
- Stimets, R. W., and Sheldon, E., “The Celestial View From A Relativistic Starship,” JBIS, Vol. 34, 1981, pp. 83-99.
- Sheldon, E., and Giles, R. H., “Celestial Views From Nonrelativistic And Relativistic Interstellar Spacecraft,” JBIS, Vol. 36, 1983, pp. 99-114.
- Davis, E. W., “Faster-Than-Light Space Warps, Status and Next Steps,” JBIS, Vol. 66, 2013, pp. 68-84.