nsors. Bacterial Protein Memory Bacteriorhodopson (BR) was one of the first building blocks of life on our planet-a protein grown by salt marsh bacteria at least 2.3 billion years ago-and it is likely to become the wave of the future in computer data storage and manipulation. BR is a tiny, rugged protein that, through billions of years of evolution, has become extremely efficient at converting light into energy. As a biological substance, the protein also enables data to be stored in three dimensions, just as it is in the human brain. A BR memory stick, called a cuvette, is a transparent vehicle that is about 1 cm X 1 cm X 3 cm. Each BR stick has the capacity to store the entire Library of Congress, which is about 10TB of information. For the average consumer, BR memory would reduce the cost and increase the portability of offline data storage. Scientists esti- mate that a 10GB cuvette would cost about US$10. For maybe US$100, you could have all the storage you might ever need. And you could stick the cuvette in your pocket, take it home, and pop it into your computer. Scientists are also anticipating the protein's use in satellite imaging, where high above the earth, its natural imper- viousness to gamma ray emission would safeguard the data it holds from sun storms and other high-energy radiation. Holographic Storage Systems To achieve a full-scale optical computing environment with great computing power, it's necessary to have memories with rapid access time and large storage capacity. A volume holographic storage device, also referred to as a holostore, is a Measurements of the Digital World xxxiii page-oriented device that writes and reads data in an optical form. The holography technology achieves the necessary high storage densities as well as fast access times. Holography records the information from a three-dimensional object in such a way that a three-dimensional image can subsequently be constructed. Holo- graphic data storage enables discs the same size as today's DVDs to store more than 1TB of data. 