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Workable Fusion Starship Proposed
Adam Korbitz writes "A former colleague of Edward Teller — father of the hydrogen bomb — has published a new paper proposing a design for what could be the first practical fusion-powered spacecraft (PDF). As described at Centauri Dreams, the design has certain similarities to MagOrion, a 1990s-era proposal for a nuclear-powered spaceship with a magnetic sail and propelled by small-yield fission devices. The proposal's author also has links to the British Interplanetary Society's Project Daedalus, a 1970s proposal for an unmanned fusion-powered interstellar probe designed to reach 12% of the speed of light on its way to Barnard's Star."
Something I've always wondered about with regards to Project Daedalus and the like is the effects of time dilation as the velocity increases. I suppose at 0.12 * C the time dilation on the probe relative to, say, observers on Earth and Barnard's star is probably minimal. But it seems to me that going faster and faster you reach a point where although it might only take the probe x number of years to reach the star, on Earth it takes significantly more time. Therefore in the case of an unmanned probe, since it's time passage on earth that matters, at a certain point it's not desired to have the probe go any faster.
This line of thought leads to some interesting, paradoxical situations. First, as an object approaches C the time dilation effect becomes such that from a frame of reference of the origin, the object never in fact can reach its destination. Would it not become in essence stuck in time? Secondly there must be some point at which if an object is travelling at x*C, there must be a speed y*C such that another object could reach its destination before the first object, even though the second object is travelling at a lower velocity relative to C. Or maybe not since both objects do experience time dilation.