second), the needed energy would be attainable. However, the physicist J. Richard Gott argues that slowing down light by passing it through a medium cannot be treated as equivalent to lowering the constant c (the speed of light in vacuum) in the equations of General Relativity, saying:One has to distinguish between the speed of light in empty space, which is a constant, and through any other medium, which can vary enormously. Light travels more slowly through water than through empty space, for example, but this does not mean that you age more slowly while scuba diving or that it is easier to twist space-time underwater.The experiments done so far don't lower the speed of light in empty space; they just lower the speed of light in a medium and should not make it easier to twist space-time. Thus, it should not take any less mass-energy to form a black hole or a time machine of a given size in such a medium.Later, Mallett abandoned the idea of using slowed light to reduce the energy, writing that, "For a time, I considered the possibility that slowing down light might increase the gravitational frame dragging effect of the ring laser ... Slow light, however, turned out to be helpful for my research." Finally, Olum and Everett note a theorem proven by Stephen Hawking in a 1992 paper on the Chronology Protection Conjecture, which demonstrated that according to General Relativity it should be impossible to create closed timelike curves in any finite region that satisfies the weak energy condition, meaning that the region contains no exotic matter with negative energy. Mallett's original solution involved a spacetime containing a line source of infinite length, so it did not violate this theorem despite the absence of exotic matter, but Olum and Everett point out that the theorem "would, however, rule out the creation of CTC's in any finite-sized approximation to this spacetime." Personal life His brother is artist Keith Mallett. Books "Time Traveler: A Scientist's Personal Mission to Make Time Travel a Reality," Dr. Ronald L. Mallett with Bruce Henderson (2006). Thunder's Mouth Press. New York. See also List of contributors to general relativity References External links Mallett's UConn homepage R. L. Mallett, "Weak gravitational field of the electromagnetic radiation in a ring laser" R.L. Mallett "The gravitational field of a circulating light beam" Ron Mallett interviewed on Conversations from Penn State My Brilliant Plan