Below I copied some text from previous messages. Perhaps DARPA should be interested in this now? With a source of antimatter readily available, we should now be "good to go" ! BTW, according to an astronomy video I watched recently, our galaxy will crash into Andromeda in perhaps 3.5+-1.0 billion years -- i.e., while our Sun is still shining pretty much like today, except a bit brighter. The Andromeda/Milky Way collision simulation video is pretty impressive; I don't know where to find it, tho. On Mon, Jun 6, 2011 at 4:04 PM, <rcs@xmission.com> wrote:

The physicist Robert Forward proposed anti-hydrogen as fuel for a starship engine. He needed 4g of anti-H2, to be annihilated and mixed with tons of regular matter (reaction mass), to travel to Alpha Centauri at a respectable fraction of c. The fuel is expensive, but has a wonderful specific impulse.

A timely observation, given DARPA's recent request for ideas on how to set up a self-sufficient agency to work on "interstellar flight in 100 years"! https://www.fbo.gov/index?s=opportunity&mode=form&id=ad1728884c2dc05a344e330... --Michael http://www.bbc.co.uk/news/science-environment-14405122 BBC News Science & Environment 7 August 2011 Last updated at 05:54 ET Antimatter belt around Earth discovered by Pamela craft At 03:38 PM 10/24/2011, Bill Gosper wrote:

A probably unfinished project engaging John a few months ago was to resurrect his unpublished "THE FEASIBILITY OF INTERSTELLAR TRAVEL" from the early 70s.

Abstract:

Optimists have proposed many schemes for interstellar travel, usually aimed at reaching nearer stars within a human lifetime, but these schemes usually involve extrapolations of present science. Pessimists, finding flaws in these schemes, conclude that interstellar travel is forever infeasible. We show that interstellar travel is entirely feasible with only small improvements in present technology provided travel times of several hundred to several thousand years are accepted. Naturally no-one will start thousand-year journeys within the next few hundred years unless fleeing a danger, because improved technology may allow earlier arrival with a later start. However, our solar system will support life for several billion years, so many-thousand- year journeys will be undertaken unless a unified society forbids it and can enforce the prohibition against even rather small groups. ----------------------- Whit Diffie and I worked rather hard to retrieve it from an unconventional character set and an extremely unconventional document compiler. (Even Julian helped, simplifying a Lagrange multiplier calculation.)

John's motivation for writing it in the first place was annoyance with what he claimed were faulty analyses published at the time. He resurrected it out of frustration that no one had corrected these analyses over the intervening decades.

In whose court now lieth this ball? --rwg