Forget solid-state computing devices -- fluid-state is the way of the future if work begun by a Berlin-based chemist is taken to its logical conclusion. According to today's New Scientist magazine, James La Clair has constructed a substance whose molecules, called SENSI, become fluorescent in the presence of Nitrogen and non-fluorescent when surrounded by Carbon Dioxide. La Clair's paper on the molecule posits its uses as the bases for a simple digital circuit: just by changing the gas around the molecule, you have yourself a simple chemical analog of binary 1s and 0s, with the molecule's binary state read by firing a laser it. If the molecule is fluorescent, it emits a single photon that can be detected -- if not, it doesn't. "This technology may some day lead to computers that only need gases and light to think," wrote La Clair. Not that the idea of using molecules to represent 1s and 0s is new, but La Clair does seem to have reduced the multi-molecule systems created by previous researchers down to a single molecule. That makes the development of microprocessor-size gas-based computing devices more feasible. La Clair's paper is also well timed, thanks to the considerable interest of late raised by an Intel employee's paper detailing the rapid approach of the physical limitations of current semiconductor technology -- circuits are becoming so small they will soon run out of sufficient electrons to work, and chip producers are running out of smaller wavelengths of light with which to etch chip circuits on the semiconducting materials from which they're formed. ®