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Features

The Prospects for a Stationary World Population

The human population is now about 3.6 billion. An extrapolation of present world demographic trends that lies between two extreme projections shows it leveling off at some 8.4 billion by the year 2100

By Tomas Frejka

The Fine Structure of the Earth's Interior

The waves sent out by earthquakes and nuclear explosions have been studied in detail with new seismometer arrays. They show, among other things, that the core of the earth has a solid kernel

By Bruce A. Bolt

Interstellar Molecules

Twenty-six kinds of molecule have now been discovered In the gas between the stars of our galaxy. Among them are carbon monoxide, water, ammonia, hydrogen sulfide, formaldehyde and methyl alcohol

By Barry K. Turner

The Asymmetry of the Human Brain

In most people the left cerebral hemisphere plays a dominant role in speech. The specialized functions of the right hemisphere are now emerging. One of these functions is the perception of melody

By Doreen Kimura

Bicycle Technology

This humane and efficient machine played a central role in the evolution of the ball bearing, the pneumatic tire, tubular construction and the automobile and the airplane

By S. S. Wilson

The Migrations of the Shad

The largest member of the herring family, much prized as a food fish, moves between the sea and its river spawning grounds with remarkable precision. Its main guide appears to be temperature

By William C. Leggett

The Origins of Number Concepts

Experiments with children indicate that they first become aware of numbers in terms of ordered sequences and only later in terms of quantities. Such findings may give rise to a newer "new math"

By Charles J. Brainerd

Departments

  • 50 and 100 years ago, March 1973

  • The Visualization of Genes in Action

  • Science and the Citizen, March 1973

  • Letters

    Letters to the Editors, March 1973

  • Recommended

    Books, March 1973

  • Mathematical Recreation

    Mathematical Games, March 1973

  • Amateur Scientist

    The Amateur Scientist, March 1973

  • Departments

    The Authors, March 1973

  • Bibliography, March 1973

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