build an interstellar spacecraft. The bad news -- It runs on unobtainium. Tyler I really wish you would stop referring to the fuel material as unobtainium. Unobtainium is a fictive term for materials that don't exist, and anti-matter has already been artificially produced in laboratory settings. jqpabc123 From a NASA report in 1999: "Right now, antimatter is the most expensive substance on Earth, about $62.5 trillion a gram ($1.75 quadrillion an ounce)." In addition to being the most expensive substance imaginable, is also the most explosive. In the quantities suggested in the article, one tiny mistake would wipe humanity from the earth. For all practical purposes, it is unobtainium. ttp://www.facebook.com/patrice.guay.9 Patrice Guay It's 25 billion a gram... but hey its still not cheap at all !!! Nasa is boosting prices to put some in their pockets :) jqpabc123 The truth is, no one really knows what it would cost to produce a gram because it's never been done on a scale any larger than a few hundred atoms. But needless to say it would be very, very expensive and very, very dangerous -- too dangerous to even contemplate production on earth even if we could afford it (which we can't). Doing so would put all of humanity at risk of annihilation toog well, we have 2 option: 1) work out a way to create (mostly) stable antimatter in large enough quantities to be a useful fuel or 2) work out a way to make it work using self sustaining fusion-breeder