Is There an Immortal Memory?

Today's technologies for storing data have vexing limitations: Dynamic random access memory chips only retain data for short times, hard disk drives are slow relative to processor speed, and "flash" memory (like that in digital cameras) is expensive. Researchers are thus searching for a fast, inexpensive memory technology that retains data even when the power is off. As [Scott][1] discusses in his Perspective, the search has identified several interesting avenues that are being actively pursued. But the real-world challenges are severe, and proponents of nonvolatile memory need to take a hard look at the practical realities before declaring success. [1]: http://www.sciencemag.org/cgi/content/full/304/5667/62