When Freeman Dyson recently addressed Flight School (a part of the PC Forum technology conference held in Scottsdale AZ in March), he cited one key driver for getting people into space in a big way: propulsion. "What you need," Dyson said, "is a launch system that stays on the ground." A case in point that Dyson favors is laser propulsion, as exemplified in the 'lightcraft' concept of Rensselaer Polytechnic Institute's Leik Myrabo. Back in October of 2000, a small test model of Myrabo's design rose to a height of 233 feet, powered by a 10-KW pulsed carbon dioxide laser. Beamed energy means that future, full-scale versions of such technology will need only a small amount of on-board propellant, sharply reducing the mass of the vehicle. The lightcraft models created so far reflect the laser beam from a parabolic mirror on the underside of the vehicle to superheat air to a temperature roughly ten times that of the surface of the Sun. The air explodes and propels the craft into motion,...

It makes sense to this former Midwesterner that Alan Kostelecky can compare light to waves propagating across a field of grain. After all, Kostelecky works at Indiana University, in a state where fields of grain are not so far from view. The theoretical physicist argues in research published online today in Physical Review D that we could consider light as the result of small violations of relativity, which compare not only to waving wheat but to "...a shimmering of ever-present vectors in empty space." Having seen my share of winds rippling across wheat fields, I know one thing: a propagating wave in a nearby crop comes with a sense of directionality. You know which way the wind is coming from, and how it's affecting the local environment. Thinking of light in such terms is a far cry from a view with a much longer pedigree, that light depends upon an an underlying symmetry that is built into nature itself. Think of symmetry this way: Spacetime in the Einstein model has no preferred...

A report from two European scientists commissioned by the European Space Agency to investigate antigravity is now available in pre-print form at the ArXiv Web site. "Hypothecial Gravity Control and Possible Influence on Space Propulsion will eventually appear in the AIAA Journal of Propulsion and Power. The authors are Martin Tajmar of the Austrian aerospace firm ARC Seibersdorf and Orfeu Bertolami, of the Instituto Superior Técnico in Lisbon. (Note: The word 'hypothecial' in the paper title is surely a mistake; I'm sure the authors mean 'hypothetical.' In any case, the word 'hypothecial' doesn't show up even in dictionaries as huge as Webster's 3rd Unabridged). ESA's original charter to the scientists had been to study the concept of gravity control, and secondly to examine the credibility of previous claims of anomalous gravitational phenomena. From the study: "...current experimental knowledge and bounds on the fundamental underlying principles of General Relativity and of...

The SETI Institute's Seth Shostak has some things to say about the future of the universe in a recent posting on Space.com, referring to current observations suggesting that the rate of expansion of the cosmos is speeding up. That could make for a long, long night: After all, most stars are older than the Sun, and the stellar population boom is definitely over. The Galaxy is graying (although the actual color change is to the red). The stars are going out. In about 100 billion years, the once-brightly spangled arms of the Galaxy will be riddled with Sun-sized carbon clinkers, black holes, and quiescent neutron stars - a hundred billion mute, stellar hulks. The fun will be over, but the decay will go on. Chaotic encounters will eventually strip planets from the corpses of their erstwhile suns, and galaxies will slowly evaporate - spewing their dark and lifeless contents into the ever-expanding void. Even massive black holes will someday melt away, adding their mass to the inert and...

Why keep a close eye on nanotechnology? The Foresight Institute's Conference on Advanced Nanotechnology, closing tomorrow at the Crystal City Marriott in Washington DC, is loaded with reasons, but for interstellar theorists, the answer is mass. Ponder this: the Project Daedalus multi-stage starship, designed by the British Interplanetary Society and the first complete theoretical study of an interstellar probe, carried 50,000 tons of fuel to push a 500 ton payload. And Daedalus used nuclear-pulse propulsion; the fuel to payload ratio gets far worse with utterly inadequate chemical rockets. Nanotechnology offers the bright promise of interstellar probes so small as to dwarf the imagination, with corresponding savings in propulsion systems, yet capable of assembling full-scale observation platforms at their target star. One of the major speakers at the Foresignt Institute conference is Robert Freitas, a giant in the field of nanotechnology and a senior research fellow at the Institute...