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P W. Anderson's bodice-ripping review (THES, November 4) of the Science Masters series cosmology books requires correction. Anderson says that inflation is "simply a phase transition of the vacuum". While inflation can arise from such a phase transition, it can also arise in many other ways which involve no phase transition. By focusing on the sign of the pressure all possibilities are included. The term "antigravity" is not merely graphic: inflation occurs when the universal pressure is negative enough for the gravitating mass to become negative.

He also omitted my remarks about the uniformity of the universe. Cosmological models "begin by treating the universe as if it were a completely uniform sea of material. The clumping of material into stars and galaxies is ignored. Only if one is investigating more specific issues, like the origins of stars and galaxies, are the deviations from perfect uniformity considered . . . One of the most striking features of our universe is the way in which the visible portion of it is so well described by this simple idealisation of it as a uniform distribution of material".

And finally, scientific communication was worse in 1948 than it is in this age of information technology.

JOHN D. BARROW Astronomy Centre University of Sussex.