TED 2008: Stephen Hawking on Extraterrestrial Life

Physicist Stephen Hawking patched into TED from Cambridge. When asked whether life exists on other planets, he presented an interesting view, summarized as follows. There are two alternatives. No: because in the course of 15 billion years of evolution, if there was advanced life in other galaxies then we should have detected any life that was within 100 light years of our radio telescopes (at least no life within 100 light years).  Yes: but if advanced civilizations tend to kill themselves off when measured over long time periods, we might happen to be measuring during a time period when prior advanced civilizations have already gone extinct and those that still exist are not yet advanced enough to generate radio signals.

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[Stanley Gill Williamson]

EXTRATERRESTRIAL LIFE
Based on projections for the future development of computer science, highly intelligent civilizations will have the following characteristics:

(1) They will be very small robots, less than 0.1 mm in size
(2) They will operate at base clock speeds billions of times faster than humans.
(3) They will form societies that can essentially last forever, in human terms.
(4) They will need a grand purpose to drive their evolution to the point that they can meet the challenge of surviving for long periods (at least ten times the current age of the universe).
(5) An example of such a purpose would be the recording of history, natural and cultural, throughout the universe (or at least the local group of galaxies).
(6) In about ten times the current age of the universe the information (e.g., cosmic background radiation) that we are using to deduce the beginning of the universe will be unavailable to new civilizations. These robotic civilizations will then introduce themselves to all intelligent life forms and bring them knowledge that can't otherwise be obtained.
(7) Because of (6), the civilization whose technology created these robotic guardians of history will be forever honored in the time-distant universe.
(8) Item (7) means intelligent biologically evolved civilizations such as ours will all eventually try to create such robotic descendants (and bring honor to their culture).
(9) Our civilization will be able to create such robotic descendants in about 200 years (maybe less, maybe more).
(10) As natural historians, these robots would not want to interfere with the objects of their studies. It would be hard, but maybe not impossible, to get them to reveal themselves or to detect them if they wished to remain undetected.

I claim these ten items give a maximum-likelihood estimate of the nature of highly intelligent life. Recall from statistics that "maximum-likelihood" does not mean "likely." It is fun to use this example as a starting point for speculation about extraterrestrial life -- speculation that accounts for the future of computer and information science (not just physics and engineering).