As potential physical reality expands, we enter a new age (the Digital Age) that offers a new form for our immortality. In The Age of Spiritual Machines (1999), inventor and entrepreneur Ray Kurzweil predicted that by 2029 that machines will claim to be conscious and that these claims will be largely accepted. In Robot: Mere Machine to Transcendent Mind (1999), computer scientist Hans Moravec forecast that robots will be as smart as humans by 2040. In a recent paper (2001), no less a computer legend than Gordon Bell asserted that two-way immortality [where one's experiences are digitally preserved, and which then take on a life of their own] will be possible within this century.

      In one sense, physical immortality already exists. Those alive today not only perpetuate the genes of their immediate ancestors, they also contain the genes of their most distant ancestors. This raises an obvious question for Digital Immortality. Is there something comparable to the gene in the digital world? In The Selfish Gene (1976), Richard Dawkins suggested there is. In answering another question (Are there any replicators on our planet besides genes?), he proposed the meme.

We need a name for the new replicator, a noun that conveys the idea of cultural transmission, or a unit of imitation. 'Mimeme' comes from a suitable Greek root, but I want a monosyllable that sounds a bit like 'gene'. I hope my classical friends will forgive me if I abbreviate mimeme to meme.

      However, the meme of a suitable theory of memes languished for over twenty years until Susan Blackmore's The Meme Machine (1999). In it, she not only elaborated the theory, she introduced two important new elements: the memeplex and the selfplex. Memeplexes are memes that come together for mutual advantage. She showed how religions, cults, and ideologies function as memeplexes, systems that protect and replicate themselves. The selfplex is the self viewed as a memeplex, a system of memes working for their propagation.

      When we compare digital storage and reproduction to the inefficiency of living systems housing and replicating memes, we see the distinct advantage of memes in digital form. What better path to immortality than the digital propagation of you as your memes? (And speaking of better paths, the hardware evolution inherent in the Internet transcends the limitations of current methods of personal digital storage and reproduction.)

      So is that all there is to the dream becoming reality, to creating Digital Immortality today? Perhaps, but it does raise some questions.

• Is Digital Immortality the inevitable realization of the dream, already evidenced by examples on the web?

• Will your immortal digital representation really be you? Are we no more than the digital selfplex, a construct of our memes? Will what survives in digital form be our consciousness?

• If the meme is the mechanism for the replication of mental life as the gene is for physical life, then shouldn't the meme produce evolution and not immortality?

• If inevitable, then we need to address the social, economic, and ethical implications while Digital Immortality is still in its infancy. If we don't, will the dream become a nightmare?

Blackmore, Susan. The Meme Machine, Oxford University Press, 1999.

Bova, Ben. Immortality: How Science Is Extending Your Life Span and Changing the World, Avon Books, 1998.

Dawkins, Richard. The Selfish Gene, Oxford University Press, 1976.

Ettinger, Robert. The Prospect of Immortality, Doubleday, 1964.

Kurzweil, Ray. The Age of Spiritual Machines, Viking Press, 1999.

Moravec, Hans. Robot: Mere Machine to Transcendent Mind, Oxford University Press, 1999.