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13 of 14 people found the following review helpful:
1.0 out of 5 stars
Poor, April 29, 2000
This review is from: Probability 1 (Paperback)
The quality and range of popular science books has substantially improved over the last 20 years. This book barely deserves to be read. The book's thesis is demonstrably unproven. It claims that it is almost certain that there is life on other planets. Simplifying slightly, let p be the probability of life on any given planet and N the number of planets. We assume that N is comparable to the number of stars. N is a huge number (typical estimates are around 10^22). So the only way that they can all be bereft of life is if p is exceedingly small. Aczel assumes arbitarily that it is small but not that small, so that the product Np is large. His result then follows. But the whole question is just how small p is. Both Freeman Dyson and Fred Hoyle have given fairly detailed arguments showing that it might indeed be exceedingly small. Others disagree. Aczel appears to know nothing of this debate.
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10 of 11 people found the following review helpful:
2.0 out of 5 stars
An unremarkable introduction to the SETI field, January 4, 1999
By A Customer
Probability 1 : Why There Must Be Intelligent Life in the Universe by Amir D. Aczel Amir D. Aczel,a professor of statistics at a small college in Massachusetts, provides a rudimentary review of various topics relevant to the search for extraterrestrial life (SETI) such as the probabilities of extrasolar planets, evolution of DNA, and lifespan of stars. He is extremely topical, if anything, as he discusses findings and reports from the early 90s up to 1998. However I cannot recommend this book to anyone who knows the Drake equation or anything about SETI going in, as this is at best an unremarkable introductory work to SETI. I'd recommend "Are We Alone?" by Paul Davies or "Is Anyone Out There?" by Frank Drake & Dava Sobel above the current work. Aczel writes best when he describes historical anecdotes: how Pascal's contribution to probability emerged from a gambling friend's request, how Gaussian receives credit for a curve that was described 100 years earlier by an impoverished math tutor. The history of science and mathematics is always interesting as it provides a context within which our now-everyday concepts developed, revealing the incremental nature of the innumerable aspects of scientific discoveries we take for granted. The title of the work -- Probability 1 - refers to his conclusion that mathematically the probability of life existing elsewhere in the universe is 100% likely, or nearly so. He supports this claim with a dubious calculation. Essentially he says that the probability of life out there = 1 - ((a-1)/(a)) ^ b where ((a-1)/(a)) is the probability of life existing anywhere and where the power b is the number of anywheres (stars) in the universe. The term heads toward zero as a and b approach infinity. b can at least be calculated with some degree of accuracy. He uses the value 30 x 10^24 as the number of stars in the universe. A reasonable assumption, I suppose. However the entire equation hangs on the value of (a-1)/a which he sets as 0.00000000000005, give or take a few zeros. This value is not yet known to any degree of accuracy and thus giving it a value and using that value concretely does not clear up the matter -- though it does provide a catchy title for a book. And even if the probability of life elsewhere in the universe is 1, do we really care if bacteria developed in a galaxy so remote from us (essentially meaning any galaxy outside of our own) as we will never be able to examine it under the microscope or communicate with its distant descendants. What we'd like to know is the probability of life (intelligent life in particular) within 50 or so light-years of Earth. That cannot be determine on a slide rule. The only way we will know during our lifetime whether life exists in the universe is through observation -- spying on planets with telescopes and listening for intersolar radio traffic... -David Kaiser Recommended books on search for extraterrestrial life/intelligence Are We Alone? : Philosophical Implications of the Discovery of Extraterrestrial Life by Paul Davies Is Anyone Out There?: The Scientific Search for Extraterrestrial Intelligence by Frank Drake & Dava Sobel
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5 of 5 people found the following review helpful:
1.0 out of 5 stars
Very disappointing, February 20, 2001
I began this book with eager anticipation that a probability theorist would offer an interesting, or at least amusing, argument, using Drake's Equation, that extraterrestrial intelligence must exist. Alas, I was very disappointed. The author writes well. His prose is easy to read. Nevertheless, his argument utterly fails. You don't need to know probability theory to see the holes in Aczel's argument. I won't repeat what other reviewers have said. For the sake of argument, let's just grant him the assumptions that half of all stars have planets, and that 1/9 of the planets in those systems occupy the habitable zone. Let's even grant him the gratuitous assumption that life will evolve from inorganic chemicals on 1 out of every trillion planets. (Actually, he speaks of "DNA evolving," which doesn't really make sense, so I'll just assume he means to calculate the probability of some sort of simple, reproducing life form). Nevertheless, even granting these assumptions, Aczel mysteriously jumps from the origin of life to the existence of intelligent, interstellar-communicating civilizations, without explanation. Drake's Equation requires that we calculate the probability of intelligent life evolving from simple life (which no one knows how to do), and maintaining itself as a civilization long enough to develop radio communications technology. Aczel, after mentioning these variables in earlier chapters, forgets them when he runs the calculation in his conclusion. I'm surprised that an editor didn't notice this slight omission. The result? His conclusion is good for little more than a marketable book title.
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