At the Edge of Time

October 1, 2019
A fine history of the universe from the Big Bang to the present. Hooper (Astronomy and Astrophysics/Univ. of Chicago Nature's Blueprint: Supersymmetry and the Search for a Unified Theory of Matter and Force, 2009, etc.), a senior scientist in the Theoretical Astrophysics Group at Fermilab, explains that the Big Bang is simply the consequence of rewinding time in today's universe, which is expanding and cooling. As time moves backward, the cosmos shrinks and becomes hotter until, 13.8 billion years ago, according to calculations, it becomes infinitely small and infinitely hot. During that early period, "matter likely interacted in ways that it no longer does, and space and time themselves may have behaved differently than they do in the world that we know." Nothing existed except a uniform soup. Since Einstein--whose theory of relativity provides the science behind the Big Bang--proved that matter and energy are equivalent, the particles that make up matter did not yet exist. After a few millionths of a second, the universe cooled enough for familiar subatomic particles (protons, neutrons, electrons) to form, but it remained too hot for these to combine. The universe was dark because charged particles (i.e., protons and electrons) soak up light. At 380,000 years ago, the temperature had dropped enough for these to combine into atoms. The universe became electrically neutral, and light spread everywhere; it is still present in the cosmic microwave background. Stars, galaxies, and planets followed. Progress in cosmology has increased our ignorance as well as our knowledge. A good sport, Hooper seems positively excited as he describes the discoveries of dark matter and dark energy, which reveal that everything we observe represents less than 5% of the universe. Beginning with Carl Sagan's Cosmos in 1980, Big Bang books have become a genre that curious readers should check out every few years to keep up with breakthroughs (gravity waves being the latest). They can't go wrong with Hooper's. A lucid account that is neither dumbed down nor overly difficult.

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