The Accelerating Universe: Infinite Expansion, the Cosmological Constant, and the Beauty of the Cosmos

"The Accelerating Universe is not only an informative book about modern cosmology. It is rich storytelling and, above all, a celebration of the human mind in its quest for beauty in all things."
—Alan Lightman, author of Einstein's Dreams

"This is a wonderfully lucid account of the extraordinary discoveries that have made the last years a golden period for observational cosmology. But Mario Livio has not only given the reader one clear explanation after another of what astronomers are up to, he has used them to construct a provocative argument for the importance of aesthetics in the development of science and for the inseparability of science, art, and culture."
—Lee Smolin, author of The Life of the Cosmos

"What a pleasure to read! An exciting, simple account of the universe revealed by modern astronomy. Beautifully written, clearly presented, informed by scientific and philosophical insights."
—John Bahcall, Institute for Advanced Study

"A book with charm, beauty, elegance, and importance. As authoritative a journey as can be taken through modern cosmology."
—Allan Sandage, Observatories of the Carnegie Institution of Washington

Livio unfortunately dallies with something that he calls the cosmological aesthetic principle-- his term-- as a new framework in which to provide and organise cosmological theories. One of the central criteria is the theory's aesthetic appeal, something related to it's symmetry, copernican nature (i.e. not singling out any particular epoch or place as being special), and its overall simplicity. Livio does present some reasonable arguments. But overall his suggestion here is of dubious merit in large part because, as is apparent throughout the book, there is too much emphasising what is desired to be seen, rather than what actually is seen. There is inherently a prior presumption about how the universe should be and should behave-- a product of a particular theoretical tradition-- when the recent findings in this and other respects suggest many surprises up ahead, even at the fundamentals. The author also seems a bit too sure of himself in regard to the recent theoretical models and ideas as well as the observations themselves. The recent findings and the constantly changing nature of science itself would argue for more care in such interpretations. So the book is worth a read as a general summary, but has problems in its basic ideas.
February 13, 2002

Livio's book fails, unfortunately, for several reasons.

(1) One problem is technical: For all the emphasis that Livio puts on beauty and the relation of excellent scientific theories to great art, his book has oddly omitted the occasional figure with an example of such great art-- paintings, sculptures, illustrations, something that a reader can relate his ideas to.

(2) Livio is clearly enthusiastic about his field and his work with the Hubble Space Telescope, and this is a good thing overall. But he becomes too enamored with the recent discoveries and does not properly think through what they are implying. Rather than humbly admitting what astrophysicists and cosmologists constantly repeat in the journals-- the fact that we simply don't know what the current observations truly mean, and what is impelling them-- Livio overreaches here. We don't know the source of the "cosmological constant" that seems to be doing the accelerating, nor exactly how it manifests (or how it did so in the past). Yet Livio claims that it basically maps out the trend of cosmological progression, then proceeds in all kinds of unfounded detail about what it means. This comes out when Livio suggests that the future is now better known than the cosmic past-- an obviously ludicrous conclusion, since not just cosmological theories but fundamental ways of regarding the cosmos and basic assumptions change, and (especially recently) with rapidity. Moreover, no matter what process is discerned, it is simply not possible to say more than the vaguest thing about what it means overall since, in general, our understanding of the universe and spacetime is developing yet still nascent in so many ways. Most puzzlingly, Livio proceeds from this shaky basis to map out a picture of the cosmos which he claims to be beautiful, but is simplistic and downright dull. Which leads to the third problem:

(3) In choosing his criteria for evaluating theory, Livio introduces a regrettable bias. Desires for symmetry and simplicity have been present since Galileo's time. But Livio seems almost obsessed with the Copernican principle. I myself share his predilection for the principle, and would hope that theorists would tend to formulate cosmological models without having to invoke anything special about earth or what has happened here. But we cannot assume up front that this is going to be the case; the evidence has to decide that, not a personal preference. When Livio cites the Copernican principle it seems to be in response to the so-called anthropic principles, the "strong anthropic principle" suggesting some kind of life-promoting design in the cosmos and the "weak anthropic principle" stating the obvious-- life is here on earth, and there must be something about the physical constants and forces that is conducive to it. Livio is justifiably hesitant with regard to the strong version, but is in danger of neglecting the obvious fact of the weak version. Earth, in some sense, might seem "messy" and "incongruent" with regard to the criteria that Livio sets up, but the planet may indeed turn out to be special, especially when the enigma of earth's biology is considered. We should not assume that up front, but nor should we rule it out; cosmological theories have to be open to different possibilities. As one reviewer below pointed out, Aristotle's musical spheres picture was very beautiful, but it turned out to be flat wrong. Accurate theories in cosmology may turn out not to have simplicity to be comprehensive, and the Copernican principle may not be appropriate, at least in certain respects; we have to be open to that possibility, which suggests that Livio's Cosmological Aesthetic Principle might be a questionable set of criteria.
December 23, 2001