If two scientists at Los Alamos National Laboratory are correct, People will still be driving gasoline-powered cars 50 years from now, giving out heat-trapping carbon dioxide into the atmosphere--and yet that carbon dioxide will not contribute to global warming. The scientists, F. Jeffrey Martin and William L. Kubic Jr., are proposing a concept, which they have patriotically named Green Freedom for removing carbon dioxide from the air and turning it back into gasoline. The idea is simple. Air would be blown over a liquid solution which would absorb the carbon dioxide. The carbon dioxide would then be extracted and subjected to chemical reactions that would turn it into fuel. Although they have not yet built a fuel factory, or even a small prototype, the scientists say it is all based on existing technology. 'Everything in the concept has been built, is operating or has a close cousin that is operating,' Dr. Martin said. The proposal does not violate any laws of physics, and other scientists have independently suggested similar ideas. In the efforts to reduce humanity's emissions of carbon dioxide, three solutions have been offered hydrogen-powered cars, electric cars and biofuels. Biofuels are gasoline substitutes produced from plants like corn or sugar cane. Plants absorb carbon dioxide as they grow, but growing crops for fuel takes up wide strips of land. Hydrogen-powered cars emit no carbon dioxide, but producing hydrogen requires energy, and if that energy comes from coal-fired power plants, then the problem has not been solved. The problem with electric cars is that they have typically been limited to a range of tens of miles as opposed to the hundreds of miles that can be driven on a tank of gas. Gasoline, it turns out, is an almost ideal fuel (except that it produces carbon dioxide). If it can be made out of carbon dioxide in the air, the Los Alamos concept may mean there is little reason to switch, after all. 'It's definitely worth pursuing,' said Martin I. Hoffert, a professor of physics at New York University. 'It has a couple of pieces to it that are interesting.' Other scientists also said the proposal looked promising but could not evaluate it fully because the details had not been published. What is most remarkable about the proposal made by the two scientists?