The staggering difficulty posed by interstellar flight pushes us to imagine alternatives to today's technologies. Using conventional rocketry we're forced to amass so much propellant that the craft we want to send seem impossible to build, even if we could afford the vast fuel bill. A jacked up rocket engine is, of course, nothing but an old technology pushed to its extreme imaginative limits. And you could sense the constraints in that vision at the recent Joint Propulsion Conference in Hartford (CT), discussed not only in these pages but also here by Ray Villard. I mention Villard's comments because while I focused on Robert Frisbee's antimatter rocket concepts in my Centauri Dreams post, Ray tackles the much broader question of how we place technologies within the context of scientific progress. The news director for the Hubble Space Telescope, Villard is well versed in the rewards and challenges of spaceflight, but he's nonplussed with some of the reaction to the Hartford...

Hugh Everett's 'many worlds' interpretation of quantum mechanics spawned not just the idea of a multiverse, but apparently quite a few interpretations on what a multiverse implies. If you're intrigued by the notion that our cosmos is one of what may be an infinite number of universes, you'll want to read Dan Falk's report in Sky & Telescope on the recent multiverse conference held at the Perimeter Institute for Theoretical Physics (Waterloo, ONT). Particularly interesting is the growth of multiverse thinking as string theory has come to the fore, with all the controversy that implies. And then there's the notion of 'eternal inflation,' which conceives of endless big bangs, each creating a separate cosmos. Laura Mersini-Houghton (University of North Carolina) is concerned about how multiverses spawned by quantum theory, string theory and inflation can be reconciled, as Falk notes: ...it's not at all clear how these different kinds of multiverses - grounded in quite different physical...

What should be the goals of the next generation of X Prizes? Peter Diamandis is just the man to ask the question. It was Diamandis' foundation that led to the launch of a private manned spacecraft in 2004, and since then his team has gone on to sponsor an automotive X Prize offering $10 million to anyone who can produce a marketable car that can get 100 miles per gallon. Sixty teams are at work on that one, and prizes focusing on renewable energy are also in the works. The big fish in the pond is the Google Lunar X Prize, which offers $30 million for the first privately funded robotic mission to the Moon. Nor is Diamandis alone. In fact, the landscape is awash in prizes. The Virgin Earth Challenge, brainchild of British aviation mogul Richard Branson, offers $25 million to anyone who designs a viable way to remove greenhouse gases from the Earth's atmosphere. For that matter, what about the Saltire Prize, for which Scotland has found £10 million for renewable energy breakthroughs?...

With our eyes on a proposed interstellar future, we don't want to neglect the real challenges of preserving the steps taken along the way. I'm thinking about this because of a post on an astronomy list (thanks to Larry Klaes for the pointer) by Richard Sanderson, who is curator of physical science at the Springfield Science Museum (MA). Sanderson is worried about the media upon which we store our information, and for good reason. Here's the issue in a nutshell: The difficulties that future historians may encounter are related to the ephemeral nature of digital information and the media used to store it. I can visit an old monastery in Europe, find a giant leather-bound astronomy book from the 17th century, blow off the dust, open it, and read the pages (provided I can read Latin). The only tools required are my eyes and hands. But imagine someone living in the 23rd or 24th century who finds an old box of computer diskettes or CDs. Even if the diskettes haven't been corrupted and the...