A New Scientist Must-Read Best Book of the Year

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Good Reviews: 16

Bad Reviews: 1

Read an Excerpt from THE UNIVERSE AT MIDNIGHT!

Mammoth new telescopes on Earth, such as the Keck Observatory in Hawaii, the Very Large Telescope in Chile, and Japan's Subaru Telescope, as well as the Hubble Space Telescope overhead, are probing the frontiers of the universe with stunning results. In 1996 astronomers pinpointed the center of the elusive "Great Attractor," a mass of galaxies 250 million light-years away that is trying to tug our Galaxy and thousands of others across the universe. In late 1997, two teams hunting supernovae in galaxies billions of light-years away shocked their colleagues by discovering that the universe's expansion is speeding up. Then in 2001, astronomers spotted a supernova near the perimeter of the known universe, its light emerging from the ancient epoch before the universe began accelerating. Meanwhile, studies closer to home--right in the Milky Way--lit up debate on the mysterious dark matter that pervades the cosmos: is it dying stars, primordial black holes, or some substance presently unknown to science? As a result of the discoveries flowing from these and other breakthroughs in astronomy, we are finally beginning to see the universe at midnight, not merely imagine it.

Dr. Croswell writes in his first chapter, "Every star the naked eye can see races around a gigantic black hole buried behind the dust clouds of the constellation Sagittarius." With insight, eloquence, and the authority of an astronomer, he proceeds to tell the riveting story of the discoveries that have revolutionized modern cosmology, while introducing the colorful and inspiring characters behind them. The Universe at Midnight puts discoveries old and new into fresh perspective, explaining what the big bang, the Hubble constant, quintessence, and the cosmological constant really mean--and offering a brand new forecast for the universe's ultimate fate: the cosmos will expand forever, forever faster, until nearly all other galaxies slip out of sight. Here is your passport for an exhilarating nighttime flight to the edge of the cosmos.

"A superb overview of cosmic exploration by one of the best astronomy writers of the early 21st century."
--Keay Davidson, author of Carl Sagan: A Life

"Ken Croswell turns our present understanding of the universe into the mystery page-turner it really is."
--David H. Levy, science editor of Parade magazine, discoverer of 21 comets

"Ken Croswell offers an in-depth yet highly readable review of the past, present, and future of cosmology. Along the way, he lays bare the life and times of the universe as imagined, predicted, measured, and occasionally stumbled upon by the world's leading cosmologists."
--Neil deGrasse Tyson, astrophysicist and Director, Hayden Planetarium, New York City

"Once again Ken Croswell demonstrates his remarkable talent for bringing the cosmos down to Earth. Literate and populated with fascinating real-life characters, The Universe at Midnight unravels the multifaceted history and science of cosmology."
--Alan W. Hirshfeld, University of Massachusetts, Dartmouth; Harvard College Observatory; author of Parallax: The Race to Measure the Cosmos

Good Reviews--THE UNIVERSE AT MIDNIGHT

New Scientist:

The book covers the whole field of modern cosmology. The first chapter sets the scene with some fascinating historical anecdotes. Then come sections on the big bang and its rival theories, dark matter, stellar evolution, the expansion of the universe, its "weight," background radiation, and much else. The text abounds in quotes from experts thus avoiding the danger of distortion or misinterpretation--most cosmologists, both past and present, have very definite views. Many of the quotes from key figures given here will not be found anywhere else.

Croswell makes no attempt to disguise the fact that our present knowledge is very limited, and that we are still uncertain about fundamentals such as the Hubble constant, which defines the rate at which the universe is expanding. There is a long and particularly interesting chapter about this. Neither can we be really confident about the age of the universe. The best current estimate is of the order of 15 billion years, but it is conceivable that this figure may be drastically modified in the foreseeable future.

The final chapter, which deals with the eventual fate of the Earth, is rather different in approach, and is highly speculative. Our planet cannot last forever, but when the situation becomes intolerable is there anything our descendants could do? As yet we cannot say, but breaking the Earth free from the dying Sun and transferring it to another star is likely to be a rather difficult matter. Fortunately, there is no need for immediate alarm.

The text is accurate, with only a few tiny and wholly unimportant slips (for example, the Large Magellanic Cloud is no longer classed as a completely irregular galaxy). The main disadvantage of Croswell's approach, however, is that the emphasis upon personalities sometimes masks the science. This is probably not the book for a reader who wants a no-nonsense, straightforward, and concise account of modern cosmology.

It is also a pity that Croswell has emphasised personal conflicts between researchers--accusations of plagiarism, attempts to claim credit for other peoples' work, and so on. Of course this does happen, but from this book the newcomer might well think that cosmologists are a jealous and arrogant breed. This was certainly not the author's intention. In places, too, the writing tends to be of what may be called the tabloid variety. "Perhaps the universe is expanding into nothing, or into God's living room, or into some physicist's laboratory. Take your pick."

But these are quibbles. The Universe at Midnight is vastly entertaining and enjoyable, as well as informative. It will be a welcome addition to any library, particularly if it is read in conjunction with a book that deals with the same subject in a more conventional way.
--Sir Patrick Moore

Contemporary Physics:

Astronomy, and perhaps cosmology in particular, is a rather strange science; I have heard that some of the more vociferous practitioners of other branches of physics claim that it is not really a science at all. In nearly every other science, study proceeds through controlled experiments, the system is set up in idealized conditions, a single variable is varied, and its consequences are recorded. Furthermore, to be certified as scientific fact, the experiment must be repeatable. In cosmology we have no ability to control the experiment, all we can do is observe it and have little hope of repeating it unless someone were to invent a big bang machine. Even worse, the universe seems to have taken perverse pleasure in hiding most of itself from us, and, quite probably, in making most of itself from vacuum energy rather than matter.

These simple facts explain, I believe, two important points which should be kept in mind when reading this book. Firstly, it is only in very recent years that firm quantitative results have become available in cosmology. Secondly, confounded for years in their searches for observations free from systematic biases which would allow them to understand the universe, most cosmologists have become at least slightly, let us say, eccentric.

This latter point is evidenced in several of the chapters, perhaps none more so than that discussing the Hubble constant. Ever since Hubble first realized that the universe is expanding, scores of astronomers have attempted to measure the rate of this expansion, encapsulated in the constant bearing Hubble's name. The Hubble constant is crucial since it sets both the size and the age of our universe. Currently, all cosmological measures of distances involve an unknown factor of this Hubble constant, and this propagates into many other measurements, such as the luminosity of distant galaxies. Croswell does a fine job of describing the decades of back-and-forth arguments over the value of the Hubble constant, interspersed with vitriolic quotes from those astronomers involved. Perhaps my favourite quote in the whole book is from Allan Sandage responding to criticism of his observations which turn up a lower value of the Hubble constant than certain other astronomers obtain: "many other people have said, we will always get 55 regardless of what the data say. That's because [the Hubble constant] is 55!" More importantly, although this chapter more than any other really demonstrates why it is so hard to obtain robust results in cosmology, the whole debate about the value of the Hubble constant is due to the difficulty in measuring something seemingly so trivial as the distances to galaxies. Measurement of distances requires climbing the rungs of the infamous distance ladder, using a patchwork of different techniques to measure ever greater distances. Just one weak rung and the whole ladder collapses.

Although the measurement of the three basic cosmological parameters has been the "holy grail" of cosmology for several decades, it is clear to anyone who has ever looked through a telescope (and I did at least once) that three numbers are not quite enough to describe the universe completely. Even Martin Rees' Just Six Numbers are probably not sufficient. The cosmic microwave background which proved the long-held belief that the universe is isotropic and homogeneous on the largest scales (the so-called "cosmological principle") contains the blueprints of the very inhomogeneous universe that we see around us. Three chapters in the middle of the book describe the quest to measure these ripples in the microwave background and the vast structures of galaxies that we see around us: filaments, clusters, superclusters, and voids. The topic of inflation, now almost universally accepted as a component of the big bang model, is also discussed in some detail. The idea that galaxies, and so ultimately ourselves, grew from quantum fluctuations generated 10**-35 seconds after the universe began is almost as romantic as that old chestnut about us being made of stardust! While it would be naive to think that we have heard the last word on the basic cosmological parameters, most of cosmology is now shifting its focus towards understanding those ripples in the microwave background and their descendants.

In some sense this is resulting in a subtle and yet fundamental shift in the way that observers and theorists interact. In the past the theoretical predictions were all rather easy to make (e.g. the spectrum of cosmic microwave background ripples depends only on well-understood and, crucially, linear physical processes) while the observers were forced to struggle to measure the properties of the entire universe using only that small fraction of its mass which happens to emit light, and even that in a not particularly well understood way. Now, however, the observers get their revenge. New instrumentation is allowing beautifully detailed data to be acquired, spanning huge ranges of wavelengths and reaching back over most of the age of the universe. The theorists meanwhile are having to contend with messy astrophysical processes, highly nonlinear systems and subtle feedback loops to name but a few of the complexities.

Still, that is my third most favourite thing about cosmology; it really involves every bit of physics that you ever learned: gravity, hydrodynamics, radiative processes, atomic, molecular and nuclear physics, particle physics, thermodynamics, and so on. Currently, one of the most active areas is in trying to understand the so called "dark ages" of our universe. Strangely, we now know much about our universe 100,000 years after its birth, and have a good deal of knowledge about it from a few billion years after the big bang to the present day. Looking at it logarithmically, that leaves about four orders of magnitude in time that we really have no information about. We know, or we think we know, that some important events occurred in this span of time. The very first structures in the universe began to form, quite possibly forming bizarre objects such as supermassive stars that have never occurred again, although their remnants may be lurking in the present-day universe. We also know that at some time in this unexplored period the first few stars and quasars were able to dissociate all the hydrogen in the universe, returning it to the ionized state that it had occupied since just after the big bang until the universe cooled sufficiently for it to recombine, thereby permitting the cosmic microwave background photons to begin their long journey towards us. Amazingly, observations are beginning to probe this era (spectra of the most distant quasars known in the Sloan Digital Sky Survey are hinting that the epoch of ionization is almost within our sights) and future instrumentation promises to provide a wealth of data. For example, plans are being made in both the USA and Europe for the next generation of optical telescopes, with diameters of 30 - 100 m, while new radio telescopes, such as the proposed Square Kilometre Array, should allow us to probe the distribution of neutral gas in the era directly.

Croswell's book proceeds in roughly chronological order. After beginning by giving us a sense of scale, and of our place in the universe, Croswell continues by addressing perhaps the oldest cosmological question of them all: why is the sky dark at night? An explanation of this fact, known today as Olbers' paradox, outfoxed astronomers for centuries, who speculated incorrectly that distant stars would be just too faint for us to see or that dust obscured their light from us. As Croswell explains, the solution had to await that most famous of cosmologists Edgar Allan Poe, who, in his Eureka, put forward the possibility that the sky is dark because the universe has a finite age. (I am not aware that Poe's work has ever gone through the peer review process and so we should treat it with some caution.) It is anecdotes such as this, and other human interest stories, scattered throughout clear explanations of the science that make this book a pleasure to read.

With that particular problem solved by a writer and poet the "real" cosmologists take over. Croswell guides us through a century of advancement in cosmological understanding, beginning with the fight between big bang and steady state pictures, a fine example of how both the scientific method proceeds and cosmology invokes almost religious questions, proceeding through the gradual acceptance that the universe is made mostly of unseen matter, and covering in some detail the recent and much heralded birth of "quantitative cosmology." Quantitative cosmology means that we now know the values of the three key fundamental cosmological parameters with reasonable accuracy (only in cosmology would numbers known to at best 10% be called "accurate"!).

In fact, they are now known accurately enough for us to make an educated guess at what the future has in store for our universe, the focus of the final chapter. As it turns out, it is fairly bleak if we accept the reality of the somewhat unpalatable lambda, the cosmological constant, as observations of distant supernovae suggest. A universe dominated by this vacuum energy will expand in an exponentially fast manner, rapidly diluting the density of interesting cosmological objects such as galaxies. Eventually nearly all the galaxies nearby will vanish. Croswell seems to be an optimistic sort of person, however, speculating that humanity might be able to outlive the death of our Sun and even the death of all the stars in our Galaxy. Nevertheless, it seems that lambda killed the cosmologist, or at least it will eventually. When all the nearby galaxies pass beyond our horizon, and the cosmic microwave background becomes undetectably faint, there will be no more need for cosmologists. That certainly inspires me to work a little harder; time is short.

Croswell generally does a very good job of explaining the science, the techniques, and the caveats relevant to the topics discussed (I encountered only one statement that I thought was just plain wrong). As I bemoaned at the start of this essay, there are, of course, innumerable popular cosmology books out there; so why should one buy this book in particular? Perhaps its strongest point is that it is actually readable! Too many such books either trivialize the subject matter, getting the science wrong, or else are so dry as to be useful only as a mild sedative. Croswell gets the balance just about right, keeping the focus on explaining the science, while mixing in enough entertainment to keep you turning the pages. The book is nicely produced with clear error-free text, and an extensive bibliography and glossary. The book ends with a set of tables, allowing armchair cosmologists everywhere to pick their own favourite values of the cosmological parameters and see just how old and large the universe should be. The only thing that I thought was lacking were pictures. I imagine colour pictures increase greatly the production costs of a book, but it would certainly be worth it; my second most favourite thing about cosmology is how beautiful the pictures are. So, I can happily recommend investing in The Universe at Midnight as it clearly demonstrates that, although cosmology is one of the oldest sciences, it remains active and ever changing. It also makes it quite clear that we remain a long way from having a full understanding of our universe. That is my favourite thing about cosmology.
--Andrew J. Benson

Publishers Weekly:

Science and Spirit:

The Universe at Midnight offers an insightful account of astronomers' efforts to map the cosmos as a whole, both in space and time. As their predecessors used latitude and longitude, present-day cartographers characterize this universal terrain with yardsticks such as the Hubble and cosmological constants, the deceleration parameter, and the value of a term called omega. As Croswell aptly illustrates, new techniques have yielded growing (but not complete) consensus within the astronomical community on the likely ranges of these measures. Many scientists believe these and other newfound results will soon resolve deep questions about our universe, such as its age, fate, and content....By focusing on the process of observation, Croswell captures the spirit of an exciting era of discovery.
--Paul Halpern

The San Diego Union-Tribune:

Croswell addresses cosmology's great questions: Is the universe finite or infinite? Has it always existed? What will be its ultimate fate? He traces the history of discovery, the multitudes of theories and mistakes, the real-life human drama of scientists bent on making their mark.

It is all eloquently done, presented in readable fashion, with a useful glossary and twenty pages of tables for those who require hard numbers and data. There may be better or more complete books on cosmology, but Croswell's is a fine addition to any library and may be the only book to cite the weight contribution of each person to the Milky Way's total mass and gravitational muster.

HUGE NUMBER ALERT!!!!!! It is, more or less: 0.000000000000000000000000000000000000003 percent.

A minuscule amount, perhaps, but as Croswell notes, "If you left the Milky Way, its stars would revolve slightly more slowly, its satellite galaxies would swing around the Galaxy slightly more sluggishly, the Galaxy's grip on its farthest-flung outposts would be slightly less secure. Thank you for choosing to live in the Milky Way."

Thank you indeed.
--Scott LaFee

Research News and Opportunities in Science and Theology:

The Physics Teacher:

Croswell does a good job with the daunting task of surveying the huge edifice of modern astronomy, or at least those parts of it (most of them) required to understand our current view of the universe, and why we believe it. Knowing what must be included, and doing so as economically as possible, is a nontrivial skill and for the most part Croswell does it well. Effective analogies are an essential tool; while many of the best are in the public domain by now, Croswell comes up with quite a few apposite new ones (new to me, anyway; there is no real mechanism for awarding credit to the inventor of a particularly enlightening analogy): "Galaxies mark the universe's expansion, just as rocking nighttime buoys indicate waves of dark water." "The planets resemble lazy employees: the closer the boss is, the harder they work."

Croswell leads us in a coherent way from the darkness of the night sky to the accelerating universe, with a somewhat higher assessment of his readership's sophistication than some works in this vein. While there are no equations, there are plenty of quantitative examples (and occasional exponential notation), and more than 20 pages of numerical tables in appendices. Croswell has a habit of introducing a complex idea in a simplified way, then letting the trade jargon take over. We are told that for galaxies "the mass goes as the square of the velocity dispersion"; "metals" in the astronomers' sense (all elements except hydrogen and helium) are introduced without definition; and terms such as "exponential" and "phase transition" also appear without apology. Perhaps audiences unfamiliar with such terms can just "bleep" over them, picking up the flavor without sacrificing essential meaning.

What sets Croswell's book apart most distinctly is a focus on individual personalities. We hear how almost every astronomer entered the field (this obligatory paragraph for each new participant does begin to get old), and we get many quotations from various sources. In many cases, this information provides a fascinating behind-the-scenes picture of the evolution of important cosmological ideas. Croswell does not shirk controversy or personal conflict; on the contrary, he revels in examples of astronomers calling each other names and makes some strong assertions. Was Baade's work really "plagiarized" by Shapley? Most extreme is the assertion that "rival astronomers...attacked [Sandage's] work, claiming that he botched the job [of measuring the Hubble constant]--perhaps deliberately." Such a claim of scientific malfeasance, made in the name of anonymous other individuals, seems excessive. Personalizing the stories of the scientific advances is a good way to lure an audience through a lot of technical details, but Croswell runs a risk of making his characters sound like squabbling schoolchildren, and enthusiastically takes sides in controversies unlikely to be as simple as they are here portrayed. {Martin Ryle, who died too soon for Croswell to interview him, suffers greatly at the hands, or recollections, of Fred Hoyle, who did not.) Gleeful citations of some of Fritz Zwicky's more intemperate writings serve no narrative purpose but one of entertainment. Finally, Croswell even gets in some jabs at "sloppy science writers."

On the whole, though, one can get a good, scientifically accurate picture of today's cosmology from this book. Few punches are pulled in the conceptually dense areas, so the work is probably more demanding than average for this genre, but the payoff is a more complete picture of some complex issues. The breathless style can get a little wearing: "The most spectacular galaxies sport breathtaking spirals that look like glowing hurricanes." "Just as other suns spangle the sky beyond the Sun, so other galaxies throng the cosmos beyond the Milky Way." Verbs are good, but it is possible to over-color one's prose.

The extensive glossary is an excellent feature, and the bibliography and notes on each chapter provide the attributions and references so that Croswell can avoid interrupting the narrative. I would recommend this book to a university colleague in another department, to an eager science-inclined student, or to anyone (seriously) interested in seeing how our current ideas of the cosmos came about.
--Stephen P. Reynolds

The New York Times Book Review:

We are in the midst of the most exciting period of cosmic discovery yet. We now have to make sense of what we've found, an absurd combination of quarks, dark matter, dark energy, and cosmic speed-up. If physicists and astronomers succeed in that quest, this will be remembered as the golden age of cosmology.
--Michael S. Turner

Harvard University:

University of Washington:

The Universe at Midnight: Observations Illuminating the Cosmos builds to a crescendo with chapters devoted to the battle over the Hubble constant, omega, and lambda, or, as the astronomer puts it, "Einstein's Curse."

The back stabbing and rivalry in Croswell's account is nothing new. Other authors have covered that tawdry ground. And others, including Joseph Silk, have offered level-headed explanations of the hows and whys of cosmology. What makes Croswell's book the great attractor is the fun he has with writing. Consider this sentence: "It is just before midnight, and stars spangle the sky: newborn stars emerging from magenta gas clouds, middle-aged suns dutifully towing planets through space, elderly red giants about to puff their atmospheres into the void."
--Deidtra Henderson

Science News:

Newsday:

Astronomy:

At the heart of Croswell's book is one huge question: What is the fate of the universe? Will it eventually contract to its singular starting point, reach a steady state of balance, or continue expanding forever?

The answer, according to the latest agonized consensus, is the latter. The expansion first observed by Edwin Hubble will continue to accelerate until all the billions of observable galaxies outside the Local Supercluster held together by gravity will disappear from our point of view.

Croswell, a Harvard-trained astronomer, traces the often vicious battles among modern professional astronomers to determine the so-called Hubble constant, which, as it turns out, is anything but constant. Knowing the rate of expansion would solve the riddle of our final fate. As the book closes, we think we know the answer, but the author is wise enough to add this postscript from Edward Harrison: "The standard model of the universe at the end of the nineteenth century was unlike the standard model at the end of the twentieth century in almost every respect. This prompts the question: Is it possible that the standard model at the end of the twenty-first century will be totally unlike that at the end of the twentieth century? The Victorians were confident that they were close to the truth. What are we to make of the fact that today there is a similar attitude?"--Nick Nichols

Astronomy and Space:

The pervading theme throughout the book concerns the theories and observations to determine the three cosmological parameters governing the universe. The Hubble constant is undoubtedly the best known; it converts galaxy redshifts into distances and determines the expansion rate and age of the universe. Omega refers to the density of matter within the universe, which slows its expansion. Dark matter, invisible to telescopes, accounts for much of the universe's mass. Will the universe eventually slow down and collapse or will it expand forever? Recent evidence suggests the latter. Lambda is the enemy of omega, an anti-gravity force that pervades empty space and accelerates the rate of expansion. When we observe a distant galaxy, we are of course seeing it as it was billions of years ago. This is the lookback distance determined by its redshift, and few people will have difficulty with this. Questions relating to where the galaxy was when it emitted the light we see and where the galaxy is now are more perplexing. Some of the figures in the intriguing tables are simply mind-boggling. Take, for example, a galaxy at redshift 6.0, indicating a lookback distance of 13.5 billion light-years (assuming a Hubble constant of 65, an omega of 0.3, and a lambda of 0.7); the galaxy was only 4.1 billion light-years away when it emitted the light and it is now 29.0 billion light-years away! You could spend hours delving into the various tables provided for various values of the three cosmological parameters.

With numerous quotations from the various astronomers involved and incisive insights from the author, The Universe at Midnight is enthralling reading and you will find it difficult to put this book down. Excellent explanatory notes, glossary, and bibliography are also provided.
--Gordon Nason

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