Customer Reviews

Probability 1

5 star:		(5)
4 star:		(8)
3 star:		(1)
2 star:		(3)
1 star:		(16)

 

 

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.

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

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.

What's the probability of life forming on a planet? To even think about making an intelligent guess, you should have an idea of what science knows/speculates about the origin of life - self-replication, a possible RNA-world, Eigen cycles and stuff like that. You will find none of this in Aczel's book. For a book that purports to tell you about the probability of life in the universe, that's pretty poor.

So how, you may ask, does the author arrive at the "probability 1" that the book takes its title from? Easy: At the very end of the book, Aczel makes what he calls a conservative guess - the probability of life is one in a trillion (or some such number)! Where does that number come from? Is it really conservative, or could the real probability be much, much lower, invalidating Aczel's claim that, all in all, the probability for other lifeforms - besides ourselves - is 1? Good questions. And not questions which this book adresses, let alone answers.

Add to this that the author gets a lot of what he tells you about astronomy, biology and physics plainly wrong, - no, pulsars do not release energy in pulses, in spite of their name; no, electrons are not baryons; no, DNA doesn't sit "inside genes" and so on - and you get an utterly misleading book.

In order to estimate the probability that there is life on other planets in our universe, you need to be aware of the Drake equation, which is stated in the first chapter, and to be able to make informed guesses of the sizes of the variables in this equation, which you can read about in the last three pages. The rest of the book, however, is merely entertainment - interesting science, astronomy and math, and it is fun to read. It's just that the title is a bit of a con. "After dinner topics for the scientifically literate" might be a better title, but it would sell fewer books. I think that the probability of reading about the chances of life on other planets in the universe, if you turn to a page at random in this book, is rather low. Buy the book only if you're not that concerned about the somewhat disingenuous title.

This is a pleasant, even charming book about the possibility of extraterrestrial life written by a mathematician who failed to read the popular literature on the subject. He thought that the general public was in doubt about the probability of extraterrestrial life, and he wanted to make one modest point, namely that because the universe is so incredibly vast, it is almost a cinch that life exists elsewhere. The problem with this is, just about anybody with an interest in extraterrestrial life knows that. Aczel thought he was bringing us a bulletin, carefully framed and double checked, and proven. What he should have known is that not only is his news is not news, but as Hamlet said to Rosencrantz and Guildenstern, "Your news is not true."

Aczel is the author of Fermat's Last Theorem, a book that enjoyed a popular success that perhaps gave him the encouragement he needed to think that he should write a book announcing to the world that he had proven, mathematically, that life does indeed exist on other worlds. Alas and alack, he really didn't prove anything. Most people are more convinced by common sense, given the billions of stars in our galaxy and the billions of other galaxies, that life must exist elsewhere, than they would ever be by such a mathematical "proof" as is contained herein. Fact is, one of the numbers Aczel plugs into his proof is not known, and is merely an assumption on his part. He declares without a shred of evidence "that the probability of life occurring on any single planet that is already within its star's habitable zone is extremely extremely remote: one in a trillion" (p. 212). Sorry, but that is not good enough. As someone else has pointed out on this site, the number could just as easily be one in a trillion, trillion, trillion. How about 1 in a googolplex of googolplexes? Size DOES matter.

Notice the full title of this book: "Why There Must Be Intelligent Life in the Universe." Aczel's entire argument includes the idea that life inevitably leads to intelligent life. In Chapter Seven, "The Evolution of Intelligence," he quotes studies showing that the brain size of animals in general is growing, that the dinosaurs had on average larger brains at the time of their demise than they did earlier, and that mammals have gradually developed larger brains.

This proves nothing of course, being (for one thing) a planetary sampling of one. Actually it proves that Aczel did not read the literature because he would have known that there is a very real controversy about whether intelligent life follows as a matter of course from life itself, or whether intelligent life is a very rare development. (See, for example, Dared Diamond's argument in Extraterrestrials: Where Are They? (1995), edited by Ben Zuckerman and Michael H. Hart.)

In the final analysis the failure of this book is not in the writing and nor in the presentation nor in the conclusion. It's in the arrogance. Just because one is an expert in statistics, it doesn't follow that one can apply one's knowledge to an entirely different field and get positive results. Furthermore, as stated above, if you are going to write a popular book, bringing the benefit of your knowledge to a popular audience, you really ought to read the literature. That way you may know as much about the subject as your prospective readership.

I was intrigued by the title of this book and bought it from a bookshop without reading any reviews, which I deeply regret now. This is one of the worst popular science books I have ever read. I bought the book in anticipation of finding some intricate argument for why extraterrestrials should exist, but instead I got this mumbo-jumbo and outright fallacies. I will not dwell on the details, but even the probability theory part, which apparently is the profession of the author (being a college teacher of statistics), is seriously misleading.

One example is the section when the normal distribution is described. First it is claimed that the normal distributions arises naturally in many cases because of the central limit theorem, which is absolutely correct. But then the author continues to exemplify the implications of the normal distribution by making use of examples where the normal distribution does _not_ apply, without saying so. Outrageous implications are drawn, like that there exists people with negative IQ just because the IQ distribution among people is well approximated by a normal distribution, and that there exists stars with negative luminosities (black holes!) for similar reasons.

The use of the "inspection paradox" to imply that we are the most advanced civilisation is simply ridiculous. As a teacher of statistics, Mr Aczel should know better than to draw conclusions from a sample of one.

But more seriously is the central theme of the book, the probability of existence of extraterrestrial life. I would say 90% of the book is largely irrelevant for this question, which is only seriously discussed in the first and last chapters. What a disappointment to find out that, after 200 pages, the argument boils down to this: We exist. Therefore there is a positive probability that ET will develop. Because there are so many worlds, even a very small probability is bound to happen. Therefore ET exists.

The problem is of course that the author, and no one else for that matter, has any slightest idea of what the probability for life to develop is, more than that it's positive less than 1. For all we know, it may well be infinitesimal. So his argument is strictly false.

It's a shame the book wasn't proof read by a scientist in the field prior to publication. It would have saved the author and editor some embarrassment. Save your time (and cents), don't read this book.

I thought the book was a tremendous let down. There is a lot of story telling and theorizing(kind of like a magician's small talk to distract from the sleight of hand that follows)...which finally leads to the conclusion:because there are a very large number of galaxies, each with a very large number of planets, no matter how small the probability that life would evolve on a planet, the probability that life has evolved somewhere else is 1. The writing is good in sections, however, the sections don't hang together. If you are going to read the book, I'd read the last couple of chapters which make all the arguments and leave you fairly dissatisfied. Even a middle school student with a rudimentary grasp of probability could make this argument. There are a couple of interesting side-trips in the book, for instance the discussion of the notion of compound probability...but the overall thrust of the book is not about what ought to be of prime interest: how did life come about?...and how did intelligence come about? The author seems to think both are inevitable...but does not make a convincing enough case

There is a good argument for the existence of extraterrestrial life, but this book does not make it.

For many years, there has been a lively debate regarding the existence of extraterrestrial life. Rather than advancing that debate, the book ignores it. The author seems to know very little about arguments others have made in support of his thesis, and he seems to know nothing about the arguments which oppose it.

This book is terrible! The relevant ideas could have been presented in just a few pages; everything else is fluff.

Other reviews have commented that the title is misleading. In my opinion it is an outright lie. Aczel's entire argument hinges on his assertion that there is no probability p for which (1-p) raised to a huge power is not effectively 0. This is simply not true and, as a mathemetician, Aczel certainly must know it (if he doesn't, he should have his degree revoked).

The author's goal was to convince people that there must be life in the universe, but I think he has hurt his case more than he helped it. Before I read this book, I assumed that there must be a good argument for life elsewhere in the universe, given the number of people who believe in it; now, however, I cannot help but wonder if everyone in the SETI community is as irrational in their reasoning as Mr. Aczel.

Reading this book was a bad experience. I feel duped, and I will think twice in the future before I buy anything from Harvest Books.