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The Hydrogen Economy

A case is made for an energy regime in which all energy-sources would be used to produce hydrogen, which could then be distributed as a nonpolluting multipurpose fuel

By Derek P. Gregory

How the Immune Response to a Virus Can Cause Disease

The body's defense mechanism may not always be beneficial. In many cases the very process that should combat a virus is itself a cause of the damage associated with a viral disease

By Abner Louis Notkins and Hilary Koprowski

The Omnivorous Chimpanzee

Observation of chimpanzees in the wild indicates that they not only eat plant foods but also hunt, kill and eat other mammals. Moreover, they display a well-developed pattern of sharing meat...

By Geza Teleki

Mars from Mariner 9

The first spacecraft to go into orbit around another planet provides evidence that Mars is just beginning to heat up internally. Systems of channels and gullies suggest erosion by water or some other agent...

By Bruce C. Murray

The Control of Sensitivity in the Retina

Interactions among nerve cells keep the response range of the system in register with ambient illumination, enabling the retina to form a high-contrast neural image over a broad range of light conditions...

By Frank S. Werblin

Judaism at the Time of Christ

Traditionally Judaism is regarded as a unified set of beliefs. New evidence indicates that between 200 B.C. and A.D. 100 its expressions were remarkably diverse, and some were even pagan...

By Michael E. Stone

Conduction Electrons in Metals

Inside crystals electrons and atoms act collectively to create waves described as quasiparticles. They help to determine whether a crystal is an insulator, a semiconductor, a conductor or a superconductor...

By M. Ya. Azbel', M. I. Kaganov and I. M. Lifshitz

Snow Crystals

The classic finely branched hexagonal crystal is only one of an almost infinite variety of shapes. Each form depends on the history of the snow crystal as it grows in a cloud

By Charles and Nancy Knight


  • 50 and 100 years ago, January 1973

  • Science and the Citizen, January 1973

  • Letters

    Letters to the Editors, January 1973

  • Recommended

    Books, January 1973

  • Mathematical Recreation

    Mathematical Games, January 1973

  • Amateur Scientist

    The Amateur Scientist, January 1973

  • Departments

    The Authors, January 1973

  • Bibliography, January 1973

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