10.D [ Nuclear Physics A128 (1969) 690--697; (~) North-HollandPublishing Co., Amsterdam

B O O K REVIEWS

A. KATZ, Principles of statistical mechanics (W. H. F r eeman and Co., London , 1967. 118 p., 64 s)

I regard this modes t t ex tbook as, by far, the best discussion in m a n y years o f the founda t ions o f statistical mechanics . Its impor tance goes, indeed, beyond tha t o f a didactic exper iment (in i tself mos t interest ing and, I th ink, mos t convincing) ; it is a ma jo r cont r ibut ion to the epistemological aspects o f the theory. The first chapters o f the book conta in a re formula t ion o f the so-called kinetic approach (with its cu lmina t ion in the H- theorem) f rom the deeper and more general po in t o f view of in forma- t ion theory; so far as I know, this is the first sys temat ic a t t empt in this direction, and the a m o u n t o f l ight it throws on the f r amework o f statistical physics is surpr is ing (at least, it has surpr ised me). The au tho r then proceeds to the considera t ions under ly ing the ergodic aspects, which he presents in su- perbly simple language and f rom the mos t heal thy epistemological s tandpoin t , never losing touch of concrete physical reality. T h e n follow the usua l developments , which (in compar i son with the usual dull exposi t ions in m a n y textbooks) seems as invigorated by a fresh breeze. The au tho r writes in a clear, incisive and delightfully common-sense style, which makes fascinat ing reading.

The only mino r poin t on which I would disagree with h im is his use o f the concept o f "dis t inguish- able part icles". This concept is foreign to a tomic t h e o r y - - f o r which it is essential tha t a toms should all have the same s t ructure and therefore, be indis t inguishable . This was unders tood bo th by Max- well and by Bol tzmann. The lat ter very clearly explained tha t what was dis t inguished in the fo rmal i sm were " labels" artificially a t tached to the a toms and carrying (so to speak) their coordinates , and tha t this feature has to be corrected by dividing with N! There is accordingly no difference in respect o f indis t inguishabi l i ty in the classical and quanta l t rea tment : the difference is in the definition o f pos- sible states o f the assembly.

I heart i ly r e c o m m e n d this book bo th to s tudents and to senior physicists. I would also recom- m e n d it to phi losophers , bu t this would be o f no avail anyway.

L.R.

H. ALFV~N, Worlds-antiworlds (W. H. F reeman and Co., San Francisco, 1967. 103 p., 25 s.)

This essay is science popular iza t ion o f the highest class. Beautiful ly written, it guides the intelligent l a y m a n t h rough the successive stages o f cons t ruc t ion o f a cosmological model , p roposed by O. Klein and the author , and based on the a s sumpt i on o f an initial " a m b i p l a s m a " or low densi ty mixture o f p ro tons and ant ipro tons . In so doing, it gives this reader a sample o f sober scientific a rgumenta t ion , such as is too se ldom found in cosmological speculat ions. A real jewel.

L .R.

L. S. RODBERG and R. M. THALER, Introduction to the quantum theory of scattering (Academic Press, Inc. , New York, 1967. 298 p., $11.50)

A. O. BARUT, The theory of the scattering matrix (Col l ier -MacMil lan Ltd., London , 1967. 350 p., 115/-)

These two textbooks cover different g rounds and operate at different levels. The first is more gener- al in scope and more e lementary than the second. The latter concentrates on high-energy physics and treats the intricate features o f this domain very thoroughly . The former is restricted to the sim- pler aspects, such as those me t in nuclear physics, and does not venture into the higher regions; it is also very thorough . A pleasing feature o f bo th is that they devote m u c h care to showing how the ra ther abstract results o f the theory can be applied to the analysis of experiments .

L.R.

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