June 28, 2012


Extreme Cosmos: A Guided Tour of the Fastest, Brightest, Hottest, Heaviest, Oldest, and Most Amazing Aspects of Our Universe. By Bryan Gaensler, Ph.D. Perigee. $16.

      We live in a weirdly improbable universe.  A science-fiction story once imagined an object whose shape was defined by pi being equal to 3 – an utter impossibility whose consequences would be quite unimaginable, since there is no way we can conceive of any such object or figure out how it could appear in our universe, where pi is an irrational number just a bit larger than 3.14.  That teeny-tiny difference, between 3 and 3.14-plus, is literally enough to define a universe.  So what are some things that can occur in ours – and, in fact, do, no matter how strange and unlikely they seem?  University of Sydney astronomer Bryan Gaensler discusses quite a few of them in Extreme Cosmos – including, for instance, a neutron star that is the roundest object known and another that rotates 716 times per second.

      Gaensler’s 10 chapters deal with extremes of temperature, light, time, size, speed, mass, sound, electricity and magnetism, gravity, and density.  Such concepts as speed, size, gravity, mass, time and light may quickly come to readers’ minds when thinking about the universe – but sound?  Yes: “The deepest note yet identified belongs to a galaxy cluster, a conglomeration of several hundred galaxies and hot gas…often nicknamed the ‘Perseus Cluster’ because of its location in that constellation.”  But what does it mean to produce the deepest note known, and how do we know that is what this galaxy cluster does?  Understanding that requires knowing a bit about what sound is and how it is produced, and Gaensler explains the basics clearly and entertainingly, using the mundane examples of an underground subway train approaching a station and an airplane breaking the sound barrier to jump off into matters that are similar in space (the process of sound production is the same) and ones that are different (the speed of sound is space is “22,000 miles per hour, about 30 times faster than the speed of sound in Earth’s atmosphere”).

      The chapter on extremes of time starts by explaining why children ask “are we there yet?” and moves into a discussion of the metallicity of a star, “the cosmic clock that allows us to search for the oldest stars.”  This chapter includes an explanation of why SDSS J1029 is considered the oldest known star and just why “the sky is a time machine.”  Elsewhere, the discussion of size not only includes the gigantism of the universe itself and of certain objects in it but also explains about “a variety of particles that have no size at all” and the fact that the size of an electron “must be less than 0.0000000000000000004% of an inch.”  The chapter on electricity and magnetism moves from the surprising statement that “planets, stars, and even entire galaxies are all magnetic” to a consideration of the “marvelous detective story” that led to the discovery of “an extremely rare species of neutron star known as ‘magnetars’” – the strongest magnets in the universe.

      And so it goes, from chapter to fascinating chapter, from an explanation of “autosomal dominant compelling helio-ophthalmic outburst” (the tendency to sneeze when one’s eyes experience bright sunlight) to a discussion of why it is not weakened gravity that causes astronauts to float when aboard the International Space Station.  What Gaensler does particularly well is relate everyday concepts and experiences to extremely-difficult-to-imagine ones, and present his comparisons and analyses in easy-to-follow language with a minimum of jargon and math and as much levity as possible (for example, one heading in the chapter on density is “Great balls of pasta”; another in the same chapter is “Bubbles of nothing”).  Extreme Cosmos does not attempt to provide any sort of strong scientific grounding in what makes the universe tick, nor does it ask readers to know large amounts of math, physics or astronomy to understand the phenomena it describes.  What it does, and does exceptionally well, is to use an investigation of extreme phenomena to shed light on the far-less-extreme ones within which we live, producing a greater appreciation of the work that astronomers do in exploring complex phenomena while helping readers understand one reason these scientists do what they do: from a sense of awe and wonder, which Gaensler generously shares with everyone who tours the cosmos with him.

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