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Wednesday, October 19, 2016

Reading List: Time in Powers of Ten

't Hooft, Gerard and Stefan Vandoren. Time in Powers of Ten. Singapore: World Scientific, 2014. ISBN 978-981-4489-81-2.

Phenomena in the universe take place over scales ranging from the unimaginably small to the breathtakingly large. The classic film, Powers of Ten, produced by Charles and Ray Eames, and the companion book explore the universe at length scales in powers of ten: from subatomic particles to the most distant visible galaxies. If we take the smallest meaningful distance to be the Planck length, around 10−35 metres, and the diameter of the observable universe as around 1027 metres, then the ratio of the largest to smallest distances which make sense to speak of is around 1062. Another way to express this is to answer the question, “How big is the universe in Planck lengths?” as “Mega, mega, yotta, yotta big!”

But length isn't the only way to express the scale of the universe. In the present book, the authors examine the time intervals at which phenomena occur or recur. Starting with one second, they take steps of powers of ten (10, 100, 1000, 10000, etc.), arriving eventually at the distant future of the universe, after all the stars have burned out and even black holes begin to disappear. Then, in the second part of the volume, they begin at the Planck time, 5×10−44 seconds, the shortest unit of time about which we can speak with our present understanding of physics, and again progress by powers of ten until arriving back at an interval of one second.

Intervals of time can denote a variety of different phenomena, which are colour coded in the text. A period of time can mean an epoch in the history of the universe, measured from an event such as the Big Bang or the present; a distance defined by how far light travels in that interval; a recurring event, such as the orbital period of a planet or the frequency of light or sound; or the half-life of a randomly occurring event such as the decay of a subatomic particle or atomic nucleus.

Because the universe is still in its youth, the range of time intervals discussed here is much larger than those when considering length scales. From the Planck time of 5×10−44 seconds to the lifetime of the kind of black hole produced by a supernova explosion, 1074 seconds, the range of intervals discussed spans 118 orders of magnitude. If we include the evaporation through Hawking radiation of the massive black holes at the centres of galaxies, the range is expanded to 143 orders of magnitude. Obviously, discussions of the distant future of the universe are highly speculative, since in those vast depths of time physical processes which we have never observed due to their extreme rarity may dominate the evolution of the universe.

Among the fascinating facts you'll discover is that many straightforward physical processes take place over an enormous range of time intervals. Consider radioactive decay. It is possible, using a particle accelerator, to assemble a nucleus of hydrogen-7, an isotope of hydrogen with a single proton and six neutrons. But if you make one, don't grow too fond of it, because it will decay into tritium and four neutrons with a half-life of 23×10−24 seconds, an interval usually associated with events involving unstable subatomic particles. At the other extreme, a nucleus of tellurium-128 decays into xenon with a half-life of 7×1031 seconds (2.2×1024 years), more than 160 trillion times the present age of the universe.

While the very short and very long are the domain of physics, intermediate time scales are rich with events in geology, biology, and human history. These are explored, along with how we have come to know their chronology. You can open the book to almost any page and come across a fascinating story. Have you ever heard of the ocean quahog (Arctica islandica)? They're clams, and the oldest known has been determined to be 507 years old, born around 1499 and dredged up off the coast of Iceland in 2006. People eat them.

Or did you know that if you perform carbon-14 dating on grass growing next to a highway, the lab will report that it's tens of thousands of years old? Why? Because the grass has incorporated carbon from the CO2 produced by burning fossil fuels which are millions of years old and contain little or no carbon-14.

This is a fascinating read, and one which uses the framework of time intervals to acquaint you with a wide variety of sciences, each inviting further exploration. The writing is accessible to the general reader, young adult and older. The individual entries are short and stand alone—if you don't understand something or aren't interested in a topic, just skip to the next. There are abundant colour illustrations and diagrams.

Author Gerard 't Hooft won the 1999 Nobel Prize in Physics for his work on the quantum mechanics of the electroweak interaction. The book was originally published in Dutch in the Netherlands in 2011. The English translation was done by 't Hooft's daughter, Saskia Eisberg-'t Hooft. The translation is fine, but there are a few turns of phrase which will seem odd to an English mother tongue reader. For example, matter in the early universe is said to “clot” under the influence of gravity; the common English term for this is “clump”. This is a translation, not a re-write: there are a number of references to people, places, and historical events which will be familiar to Dutch readers but less so to those in the Anglosphere. In the Kindle edition notes, cross-references, the table of contents, and the index are all properly linked, and the illustrations are reproduced well.

Posted at October 19, 2016 13:08