Interstellar travel is just an antimatter of time.
Energy from particle annihilation could cut voyages by light years.
Keay Davidson, Chronicle Science Writer
Sunday, August 8, 2004
"Matter/antimatter annihilation represents the 'ultimate' source of stored energy for space propulsion," says a November 2002 report from NASA's Marshall Space Flight Center in Alabama.
"Today's rockets use chemical fuel, which is too weak and heavy to support an interstellar mission. The nearest stars are more than 20 trillion miles away; a trip by chemical rocket would take thousands of years.
"By contrast, antimatter engines would accelerate so fast that the mission would be much shorter. Howe and his colleagues have calculated that with 17 grams of antimatter -- barely enough to hold in your hand -- a robotic space probe could get to Alpha Centauri in 40 years. To get there in a decade, the rocket would need at least four times as much antimatter.
"Interstellar flight requires quantities of antiprotons that we can't even imagine producing at this point," acknowledges Howe, whose firm is largely funded by the NASA Institute of Advanced Concepts. But time might change everything; he notes that in the early 1940s, there were only "micrograms of enriched uranium (for nuclear bombs) available to the world.
"At that time, if you said you'd need a ton of it, it would have seemed impossible. But nowadays, we have so many tons of it, we've quit making it."
http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2004/08/08/MNG0984OM41.DTL

Considering the pace at which phyiscs is advancing I believe we will know how to produce and store antimatter in large amounts within just a few decades.
The other suggestion of exceeding light speed is much more controversial of course. But the history of high energy particle physics is such that new physics is observed when we increase the power in our accelerators markedly.
There is evidence from cosmic rays at energies over a millions times higher than what we can currently reach with our accelerators of new physics occurring. One of the suggestions being seriously discussed in physics journals is that at these ultra high energies light speed can be exceeded.
For more on this google "ultra high energy cosmic rays".

Bob Clark