July 23, 2004 4:56 PM PDT
Intelligent life up there? Wait 20 years
Seth Shostak, the senior astronomer at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, Calif., has calculated that the rate of improvement of radio telescopes will enable astronomers to detect radio signals from other civilizations in the galaxy, assuming that they are out there, by 2025.
"We're not very far from success or not," he said. "This is an experiment that may not be generations away."
The calculation largely comes from the interaction of known quantities about the galaxy, the rate of technological progress, and assumptions about alleged life on other planets.
The galaxy measures approximately 100,000 light years across, Shostak said. Radio telescopes, meanwhile, double in performance approximately every 18 months. This is a result of Moore's Law, which states that the number of transistors on a chip doubles about every 24 months.
As a result of the continuing performance improvement, scientists will be capable of scanning more of our neighborhood in the universe for radio signals--at an increasingly faster rate. Using the needle-in-a-haystack analogy, these two numbers enable scientists to determine the size of the haystack and the rate at which we can sift through the hay.
The unknown question is how many intelligent, radio-transmitting civilizations are out there. Noted Astronomer Frank Drake calculated that about 10,000 could exist in our galaxy. Carl Sagan and others have put that number in the millions.
Using the conservative Drake figures, Shostak estimated that we could come across an alien signal in 2025. Many have said Moore's Law could begin to slow down over the next two decades, but most believe that computing power will continue to progress.
Under Drake's figures, intelligent civilizations should be about 1,000 light years apart, assuming that such civilizations exist.
"It is a prediction based on assumptions," he said. "How many planets like Earth are out there?" But much of SETI's work is largely based on similar assumptions.
Closer to home, the effort will also require funding. The Allen Telescope Array, being partly funded by Microsoft co-founder Paul Allen, will begin to scan the galaxy this fall. It will have 32 antennas. There are plans to expand it to 350 antennas, but that will require about $10 million.
Astra Astronautica plans to publish a full paper on this theory Monday.
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