Gamow on Gravity

"Gravity rules the universe."

(page i)

Book review, Title Gravity, Author George Gamow, Rating 4.5, Galileo, Newton and Einstein on Gravity

Gravity George Gamow Book review

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This is an explication of the modern understanding of Gravity for an audience comfortable with algebra and geometry. The author reasons tightly, so the book cannot be read lightly. But those genuinely curious about the intellectual story of gravity will find in the physicist George Gamow a superb teacher, one adept at explaining physics to the uninitiated, children or adults, and to the newly initiated, high school and college students.

Gamow begins with Galileo’s invention of the modern scientific method, in which he moved away from medieval Aristotelean concepts and approaches. The author shows how, through experimentation with pendulums and with objects dropped from a tower or rolled down inclined planes, Galileo came to a more rigorous understanding of the motion of falling bodies. Not only did he determine that the bodies were under constant acceleration, but he showed that the acceleration was independent of the size of the body. Galileo also discovered the principle of superposition of motion, noting that there were two motions, the horizontal propulsion and the vertical fall. His precise measurement of time were central to his efforts to understand motion, and lead to the wide-spread use of pendulum-driven clocks.

Gamow follows on with Newton’s development of the Law of Universal Gravitation. Newton relied in part on Galileo’s insights here to combine the hitherto separate terrestrial and celestial explanations of falling bodies. In his treatment of celestial mechanics, the author provides a demonstration that Newton’s Laws of Motion and Universal Gravitation incorporated and proved Kepler’s Laws of Planetary Motion.

Gamow applies Newton’s principles to planetary orbits, the tides, and the concept of escape velocity, and explained how these principles were used to identify the as-yet-unobserved planets of Neptune and Pluto. To lay the groundwork for his explication of Einstein’s General Theory of Relativity, Gamow spends some time describing the wobble of planets that rotate on their axis.

What is particularly valuable in this book is the author’s use of geometrical arguments to explain the reasoning of Galileo, Newton and Einstein. For example, Galileo developed accurate mathematical models of falling bodies using in part proto-calculus methods. Gamow carefully walks the reader through the development of these models, and shows how Galileo imitated Archimedes’ method for determining geometrical volumes to determine the equation for the constant acceleration of a falling body with respect to time. The author also demonstrates how some of the rudiments of calculus were later developed by Newton from this approach.

This book would make an excellent addition to a high school AP Physics class.