Space and Time in the Light of Modern Physics

Book Reviews

H. Witte, Raum und Zeit im Lichte der neueren Physik (Sammlung Vieweg Tagesfragen aus den Gebieten der Naturwissenschaften u. d. Technik), third edition, 1920, p. 88.

H. Witte’s small book is written for a very broad circle of readers. Its content is an exposition of the “special” principle of rela-

of A. Einstein’s relativity. The author makes no use at all of mathematical symbolism, resorting at the most difficult points, for example, to Cohn’s model of a system at rest and in motion. It cannot but be noted that such a mode of exposition is extremely cumbersome; let us point out, for instance, that to describe the scheme of Michelson’s experiment—and that very approximately—the author requires more than 10 pages. In general, the absence of a mathematical formulation of Einstein’s principle deprives the exposition of cogency. If in many monographs on the same question the physical forest is very often not visible for the mathematical trees, then in Witte’s little book it is true that the trees are not visible, but the outlines of the forest are sufficiently vague and, in our opinion, will be entirely indistinguishable to a reader not already acquainted with the mathematical form of the principle.

Very interesting is the first part of the book, where the author, known for his profound critical analysis of the concept of ether, examines the principal features of the scientific concept of space and time, gathering them into two groups:

I {
    a) An arbitrary, but once-and-for-all definite, choice of origin and coordinate axes.
    b) An arbitrary, but once-and-for-all definite, choice of spatial scale.
II {
    a) An arbitrary, but once-and-for-all definite, choice of zero point of time.
    b) An arbitrary, but once-and-for-all definite, choice of unit for measuring time.
}

The very choice of a coordinate system is limited by the performability within it of the laws of nature. The development and generalization of the principle of relativity amounts, according to Witte, to the successive elimination of all the indicated marks of time and space.

Unfortunately, the outlines of the “residue,” i.e. of the modern conception of time and space remaining after the removal of the principal marks, are by no means clear in Witte’s exposition.

The book under review does not touch upon Einstein’s recent works, which have completed the theory of relativity and have given it a dizzying generality. Therefore the appearance of a new edition of the book in 1920 without any additions seems somewhat strange.

S. Vavilov.