In my opinion antimatter will be the eventual solution to interstellar space travel due to its efficiency in using small amounts of it to produce large distances in space travel. At CERN they are able to produce several trillionths of a gram of antimatter at a cost of $20 million. Total worldwide production to date has been a few nanograms. Although that may seem like minuscule amounts produced it is 10-12 kilograms compared to what physicist Michio Kaku quotes Gerald Smith of Pennsylvania State University estimating that 4 milligrams of antimatter would take us to Mars (a milligram of antimatter is 10-6 kilograms). In terms of a size comparison we would need to move from production of antimatter from the size of a human cell to the size of a Mosquito. Kaku says that it is conceivable that if an atom smasher was built specifically just to produce lots of antimatter (current atom smashers have various purposes that are in demand) combined with mass producing these machines we could get antimatter production up significantly.
