Gravitation und Raumzeit: Die vierdimensionale Ereigniswelt der Relativitätstheorie

Scientific American Library Series #31

by John Archibald Wheeler, Claus Kiefer (Translator)

Gravity is not a force acting at a distance. It is mass gripping spacetime, telling it how to curve, and spacetime gripping mass, telling it how to move. According to preeminent physicist John Archibald Wheeler, gravity makes the closest connection between the world we see around us and the inner-most workings of the universe.

In this imaginative volume, Wheeler explores gravity and spacetime by applying Einstein's battle-tested theory to both familiar and exotic phomomena--everything from flying tennis balls, to hurling gravity waves from crashing stars, the motion of the planets, and the collapse of a star into a black hole. It's a provocative, revealing, fully engaging scientific journey led by a frontline participant in the most important work in physics in the last 50 years.

Genres: Science, Physics, Stem

257 pages, Hardcover

First published March 1, 1990

About the author

John Archibald Wheeler (born July 9, 1911) is an eminent American theoretical physicist. One of the later collaborators of Albert Einstein, he tried to achieve Einstein's vision of a unified field theory. He is also known as the coiner of the popular name of the well known space phenomenon, the black hole.

Reviews

[J.D. Steens · Rating 3 out of 5]

Wheeler writes that gravity "is not a foreign and physical force transmitted through space." Rather, and following Einstein, gravity is the product of "curved spacetime geometry" that "grasps mass, telling it how to move" so that mass follows the contours of space. Wheeler then adds the other half of this equation by saying that mass in turn "grasps spacetime, telling it how to curve." As the natural state of mass is free float through curved space (see below), the notion of space ("time" here seems to only muddle the explanation) grasping mass is understood (e.g., a ball floats downhill into a depression). Why does mass depress space so that it grasps - curves - space? Perhaps using old language, Wheeler refers to an "attracting object" but this seems to mean that (relative) mass creates the depressions. While we can understand mass as some sort of "weight" that depresses space, Wheeler doesn't say what spacetime itself is. If it is something that "grasps" or something that is "grasped," presumably it is more than a void.

The best part of Wheeler is in his opening chapters where he highlights that a body's natural state of motion is a free float. This he opposes to free fall, perhaps because there is no up or down from some fixed point of space. Yet, doesn't a body "fall" toward an attracting mass? It's also not clear why float is the preferred term as "float" suggests a resting on something else, in this case, space, that is moving. If that's the case, then a floating body is a "victim" or "slave" of something else. As it floats, it is not so free after all (Wheeler has an interesting discussion of the "master-slave relationship between mass and spacetime"). Also, as an attracting body pulls an attracted body through curved space toward itself, here too the attracted body is a "slave." Additionally, Wheeler states that "free float" only applies when an object is "totally free of drag...as in the space far above the Earth." If space is "free of drag," that suggests what? Is space "nothing" and not "something"? Finally, if a non-life object is a "slave," is this not its distinction with life, which self-propels through space and time and protects its freedom of movement based on self-regulatory adjustments to what the external world sends its way?

[Tracy Duvall · Rating 2 out of 5]

Unless, like me, you have sentimental reasons to read something by Wheeler, this book is not for you. This is because Wheeler assumes that the reader has an unusual combination of knowledge, ignorance, and interests; in addition, it's out of date on a few topics. Wheeler does try hard, though - I haven't seen so many exclamation points from a man of scientist since reading Dr. Seuss.

[Vu Nguyen · Rating 5 out of 5]

Great book by JAW on gravity, himself student of AEinstein. I have read it over 10 times. A 10 out of 10. Don’t expect to sit through one afternoon and able to grasp the details. If you don’t have enough patience, it may not be the science book for you.

[Jonathan Hockey · Rating 3 out of 5]

Mainly just reading the first few sections for now, to get an idea of how he uses his free float concept to explain gravity and spacetime. Many ambiguities remain in the mainstream perspective even from what I can see. The concepts are visually useful, but as far as providing a physical explanation. I think there is a kind of admission of defeat on this front by accepting the need to move to an informational approach.

[Francis · Rating 5 out of 5]

A lavishly illustrated gem of scientific exposition, straight from the originator of the black hole. Makes concepts such as Minkowski spacetime, geodesics, and conservation of momenergy remarkably clear with well-chosen graphics and vivid, evocative prose. While I confess that I found the poetic odes that begin the chapters a bit awkward, anyone who has the wherewithal to write a lyrical paean celebrating Cartan's differential form formulation of general relativity deserves commendation.

[Edward Cramp · Rating 3 out of 5]

A simple introduction to relativity.