And yet it happened, iterating all the way up to HAL-9000

Here's his paper: http://arxiv.org/PS_cache/arxiv/pdf/0712/0712.1649v6.pdf Besides discussing a mechanism, he also does some quick calculations about how much energy would be required to use this method to fly at light-speed. "Let us consider a spacecraft of dimensions 10 m x 10 m x 10 m ... The total amount of energy 'injected' locally would equal 10^45 J ... roughly the mass-energy of the planet Jupiter."