If we ever develop a true ‘warp drive’ that can take us to the stars well within a human lifetime, we’ll probably look back at Miguel Alcubierre as the theorist who took a science fictional idea fully into the realm of scientific calculation. The physicist’s 1994 paper (reference below) suggests that manipulating the spacetime continuum itself could allow a spacecraft to move within a ‘bubble’ enclosed by the warp. It would never break the light barrier but would ride on the spacetime distortion to arrive at its destination as if it had. “A propulsion mechanism based on such a local distortion of spacetime,” wrote Alcubierre, “just begs to be given the familiar name of the ‘warp drive’ of science fiction.”
It’s quite a notion, isn’t it? In essence, you want to create more spacetime behind your bubble while contracting what’s in front of it. The British Interplanetary Society notes that Alcubierre’s original paper has inspired about fifty publications probing the intricacies of the concept. One of the most troubling is a paper by Michael Pfenning and Larry Ford which raises the question of energy. In their view, the Alcubierre drive would demand more energy than is available in the entire universe. Chris Van den Broeck later produced a variation demanding no more than the energy output of a single star, so I guess we’re making progress of sorts.
Clearly, we have a long way to go before any spacecraft powered by a warp drive becomes feasible, if it ever does (and we haven’t even started talking about negative energy yet). It’s heartening, though, to see that the BIS is putting out a call for papers for a symposium on the matter to be held later this year. From the announcement:
In an effort to generate interest in solving some of the technical problems a symposium is being organised with the intention of focussing on four main themes: The Current Status of the Warp Drive Proposal; Quantum Field Constraints; Photon Propagation through the Warp Field; Alternative Faster than Light Drives. Where the latter may be based upon alternative versions of Einstein’s gravity such as Brans-Dicke theory or Yilmaz theory, or based upon alternative suggestions for interstellar travel such as the Krasnikov tube and wormholes.
The address for submissions: 27/29 South Lambeth Road, London SW8 1SZ, or via email to email@example.com; full details are in the link above. Needless to say, this is the kind of effort that the Breakthrough Propulsion Physics program would have mounted if NASA had continued its funding, and it is a reminder of how far the space program in the US has wandered away from theoretical subjects like these in its quest to keep Space Shuttles and the ISS flying. But that, I suppose, is an argument for another day.
The papers mentioned above are Alcubierre, “The Warp Drive: Hyper-Fast Travel Within General Relativity,” Classical and Quantum Gravity 11 (May 1994): L73–L77; Pfenning and Ford, “The Unphysical Nature of ‘Warp Drive,’” Classical and Quantum Gravity 14 (1997): 1743–51; and van Den Broeck, “A ‘Warp Drive’ with More Reasonable Total Energy Requirements,” Classical and Quantum Gravity 16 (1999), 3973–79.
Related: New Scientist looks at another way to travel vast distances quickly (in this case, perhaps between individual universes): the wormhole. Are black holes now under study actually wormholes? Physicists Thibault Damour (Institut des Hautes Etudes Scientifiques, France) and Sergey Solodukhin (International University Bremen, Germany) make the case for this interpretation. Click here for more.