One way of understanding the object of science is that it is to establish theories about the empirical world that are most explanatory. An explanatory theory will first of all accurately accomodate past observations and it will predict future observations; however, this alone will not be sufficient to establish a theory. After all, given a finite set of observations, several theories may be capable of providing equally successful explanations. In such circumstances, other considerations come into play. Commonly, "simplicity" is included among those considerations. A theory which posits fewer independent elements (forces, entities, etc.) is preferred by most scientists, and so, in the course of the Copernican Revolution, the Aristotelian idea that the universe is composed of two different entities, terrestrial and celestial, and that these entities obey different laws of motion was rejected for a theory according to which all physical bodies obey a single law of motion. In the 19th century another simplification of physical theories took place when electrical and magnetic forces were unified in a single theory of electromagnetic forces.
In A Tear at the Edge of Creation Marcelo Gleiser accepts the view that the desire to simplify physical theories into a single, unified "theory of everything" can be traced to the ancient Greek Ionian philosophers. Following Gerald Holton and Isaiah Berlin, Gleiser calls this impulse "the Ionian Enchantment" or "the Ionian Fallacy." Gleiser attempts to "unmask" this fallacy. He suggests that there is no reason to think that all phenomena in the universe can be explained by a single theory -- that the universe is "asymmetric" and "accidental."
His book is composed of five chapters. The first chapter is a relatively breezy introduction to the Ionian Fallacy, with a healthy dose of autobiographical passages thrown in. The second, third, and fourth chapters are general introductions to cosmology, particle physics, and the origin of life respectively. In each chapter, Gleiser seeks to underscore the oddity and irregularity of the universe. By this, he believes he is able to establish his claim that there is nothing common about our universe. Instead, its existence, particularly the existence of intelligent life is extremely rare and possibly unique in the universe. The final chapter emphasizes this conclusion and draws the moral from it: because we are so special, cosmically speaking, we should take greater care to protect the survival of life on our planet and especially our species.
In his introduction, Gleiser explicitly excuses his readers from reading the three chapters on science. Clearly, he recognizes that a lay reader, particularly one with only a slight background in science, is likely to be overwhelmed by the blizzard of detail he provides. He attempts to cover so much ground that he can not give sufficient explanation to many, if not most of the science in any of the three science chapters. Some might call it a "slog" to get through these chapters; however, anyone with a moderate background in science and an interest in building on that knowledge will probably appreciate Gleiser's attempts to highlight the difficulties that theoreticians have had in developing a unified theory in any of the three fields Gleiser examines.
Setting aside the intelligibility of the science chapters, the general claim is one that seems curious and possibly untestable. The main thrust of Gleiser's argument is that science has failed to uncover a single "theory of everything." Furthermore, the more we learn about the universe, the more we learn that we have more to learn. Gleiser concludes that this is evidence that the universe is not amenable to explanation by a theory of everything. That there is not a "oneness" in the foundation of the universe.
Perhaps there are scientists who have a romantic attachment to the oneness of the universe, but I suspect most merely seek simpler theories on the grounds that they are theoretically superior to needlessly complex theories. Scientist reasonably employ Ockham's razor when confronted with two theories that equally well describe and predict observations. Curiously, Gleiser dismisses the importance of Ockham's razor when deciding between theories by asserting that is should not be employed when one theory is observationally superior to another. Of course not, but that misses the point. Ockham's razor or the preference for simpler, but empirically equally good theories is an operational principle. Granted: going beyond this and asserting that the world will ultimately be amenable to a unified theory is a step too far, but so too is making the opposite assertion that the world will never be amenable to a unified theory. Early in his career, Gleiser was a "unifier." He seems to have swung to the opposite pole. He needs to find a resting place in the middle ground: science explains the world through theories which cannot reveal the absolute truth, but should always strive to explain the world according to simpler theories. To do otherwise would be to spin out any number of fanciful entities that are no more testable than the most crass religious dogma.
Gleiser's final conclusion, that the rarity (and possible uniqueness) of our existence can be a powerful force to motivate protecting our survival seems a rather weak contribution to the a argument. Humanity is certainly arrogant enough -- self-absorbed enough -- to want to continue the species regardless of the presence or absence of other intelligent life in the universe, but if it motives Gleiser (or anyone else), that's all for the good. I suspect the real challenge will be to impress upon people the mechanisms through which our collective behavior is undermining the conditions for our children's survival (or even just our own continued well-being.) Such an understanding will do much more to address our global political and environmental crises than the threat of the extinction of a unique intelligence in the universe.
All in all, Gleiser seems to have been an idealistic "unifier," who has lost his faith and instead of simply accepting the utility of simple theories, he has embraced a new religion based on an assumption of the "asymmetry" of the universe. Happily, from this, he has found a new reason to value humanity, but humanity is hardly in need of hightened valuation.