Enforcing the Clean Air Act of 1970
The act calls for the substantial reduction of pollutants by 1975. Its provisions are now the subject of many adversary proceedings. In the long run a new kind of cost-benefit analysis may be needed
Features
The Anchovy Crisis
Over the past decade the world's largest fishery has been in the Peru Current. A periodic ecological disturbance, combined with the heavy fishing, now threatens to destroy the industry
The Dynamics of the Andromeda Nebula
The stars, dust and gas of this spiral galaxy are all in motion. Spectrographic observations show that they do not simply wheel around the galactic center but move in a quite complex pattern
Ultrafast Phenomena in Liquids and Solids
Intense laser pulses a trillionth of a second in duration are harnessed to probe the extremely rapid energy-transfer times characteristic of events in the submicroscopic world
Electronic Numbers
Numeric displays are now seen not only on laboratory and industrial devices but also on pocket calculators and wristwatches. Deciding what kind of display to use involves both technology and economics
Life in Tall Trees
The high forest canopy consists of more than branches and leaves. Entire communities of other plants and animals dwell within this unique ecosystem, helping to provide the trees with nitrogen
The Human Lymphocyte as an Experimental Animal
Maintained through many generations in laboratory cultures, the cells that make antibody lend themselves to studies of cell differentiation and diseases incolving the immune system, which may include cancer
An Advice-Taking Chess Computer
It has now been 24 years since Claude Shannon outlined how a computer could play chess. Here is a description of the first machine able to take lessons from a master
Departments
50 and 100 Years Ago, June 1973
Science and the Citizen, June 1973
- Letters
Letters to the Editors, June 1973
- Recommended
Books, June 1973
- Mathematical Recreation
Mathematical Games, June 1973
- Amateur Scientist
The Amateur Scientist, June 1973
- Departments
The Authors, June 1973
Bibliography, June 1973