The book begins with the subject of
mirror reflection, and from there passes through symmetry in
geometry,
poetry,
art,
music,
galaxies,
stars,
planets and living
organisms. It then moves down into the
molecular scale and looks at how symmetry and asymmetry have evolved from the
beginning of life on Earth. There is a chapter on
carbon and its versatility and on
chirality in
biochemistry. The last several chapters deal with a conundrum called the Ozma Problem, which examines whether there is any fundamental asymmetry to the universe. This discussion concerns various aspects of
atomic and
subatomic physics and how they relate to mirror asymmetry and the related concepts of chirality,
antimatter,
magnetic and
electrical polarity,
parity,
charge and
spin.
Time invariance (and
reversal) is discussed. Implications for
particle physics,
theoretical physics and
cosmology are covered and brought up to date (in later editions of the book) with regard to
Grand Unified Theories,
theories of everything,
superstring theory and .
The Ozma Problem The 18th chapter, "The Ozma Problem", poses a problem that Gardner claims would arise if Earth should ever enter into communication with life on another planet through
Project Ozma. This is the problem of how to communicate the meaning of left and right, where the two communicants are conditionally not allowed to view any one object in common. The problem was first implied in
Immanuel Kant's discussion of a hand isolated in space, which would have no meaning as left or right by itself; Gardner posits that Kant would today explain his problem using the reversibility of objects through a higher
dimension. A three-dimensional hand can be reversed in a mirror or a hypothetical
fourth dimension. In more easily visualizable terms, an outline of a hand in
Flatland could be flipped over; the meaning of left or right would not apply until a being missing a corresponding hand came along.
Charles Howard Hinton expressed the essential problem in 1888, as did
William James in his
The Principles of Psychology (1890). Gardner follows the thread of several false leads on the road to the solution of the problem, such as the magnetic
poles of astronomical bodies and the chirality of life molecules, which could be arbitrary based on how life locally originated. The solution to the Ozma Problem was finally realized in the famous
Wu experiment, conducted in 1956 by Chinese-American physicist
Chien-Shiung Wu (1912–1997), involving the
beta decay of
cobalt-60. At a conference earlier that year,
Richard Feynman had asked (on behalf of
Martin M. Block) whether parity was sometimes violated, leading
Tsung-Dao Lee and
Chen-Ning Yang to propose Wu's experiment, for which Lee and Yang were awarded the 1957
Nobel Prize in Physics. It was the first experiment to disprove the conservation of parity, and according to Gardner, one could use it to convey the meaning of left and right to remote extraterrestrials. An earlier example of asymmetry had actually been detected as early as 1928 in the decay of a
radionuclide of
radium, but its significance was not then realized. ==Literary references==