Dark power: Grand designs for interstellar travel - space - 25 November 2009 - New ScientistNew Scientist presents two ideas for achieving interstellar travel within the human lifetime.
The first proposal is by physicist Jai Liu who sees a Bussard ramjet powered by dark matter. One theory of dark matter is that is composed of neutralinos, particles that have no antiparticles except itself. The limitation of the idea is that the ship would have to travel through areas rich in dark matter, but would only weigh 100 tonnes and need a collecting area of 100 square metres. Liu speculates that one reason we have never been visited by extraterrestrials is that our region is low, a problem that would hinder our ability to create a dark matter-powered spaceship.
The second proposal was by mathematicians Louis Crane and Shawn Wetmoreland involved using the Hawking radiation emitted by a million-tonne black hole the size of an atomic nucleus. Once constructed, the emissions by the black hole would be collimated by a parabolic mirror to form the exhaust of the ship for a journey of no more than 100 years (the lifetime of a black hole that size). Smaller black holes would generate more energy per unit mass but would have much shorter lifespans. As a side note, they suggest that one way to identify an advanced civilization would be to detect high-frequency gravitational waves generated by a black hole propulsion system. Current gravitational wave detectors, such as LIGO, only detect low-frequency waves.
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