ISSN:0031-9228    

DOI:10.1063/1.3070880

出版商:AIP    

年代:1972

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3070881

出版商:AIP    

年代:1972

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3070882

出版商:AIP    

年代:1972

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3070884

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The University of Arizona and the Smithsonian Astrophysical Observatory are collaborating to build a large optical‐infrared multimirror telescope. The telescope will have a light‐collecting area equal to that of a conventional 176‐inch telescope, but will consist of six 72‐inch telescopes mounted on a common framework in a hexagonal array around a common axis with their images combined on this axis through two plane‐mirror reflections. The six‐barreled tube structure will be supported in an altitude–azimuth geometry and will be located at SAO's Mt. Hopkins station (elevation 8500 ft), 40 miles south of Tucson, Arizona.

ISSN:0031-9228    

DOI:10.1063/1.3070886

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Many nuclear physicists working with big tandem Van de Graaffs would like to raise the energy of their accelerators by buying new acceleration tubes from. High Voltage Engineering Corp. In tests with its own MP‐0 (Emperor) tandem Van de Graaff, High Voltage reported that voltages as high as 14.4 MV were achieved, which the company says is the highest dc voltage ever applied to an acceleration tube. In the past, tandems only ran at 10–11 MV on terminal; beyond this value the tubes would fail. With the new tubes, a conventional tandem would be able to run at 28–30 MeV.

ISSN:0031-9228    

DOI:10.1063/1.3070888

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A child's view of physics is not as “childish” as we might think. On the contrary, it raises a series of problems that might interest an historian of science or even a physicist who, comparing the present state of physics with earlier stages of development, asks why certain ideas have been better able than others to resist the upheavals that have occurred in physics since the turn of the century. In our studies of children we have observed them playing with simple toys, questioned them about their perceptions and posed problems for them to solve. From these studies, we have learned something of the way a child's mind develops mathematical and physical concepts—such as topology, speed, time and causality—as well as something of the nature of the ideas themselves.

ISSN:0031-9228    

DOI:10.1063/1.3070889

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

At a recent science convention, we had a display table showing some of the materials developed by the Elementary Science Study. One of the items on display was a small motor, made from one D cell, two fahnestock clips, a rubber band, 16 inches of enameled copper wire, two safety pins and one small flat magnet. The rotor for the motor is made by winding the wire around your finger, leaving the two ends protruding about an inch on opposite sides of the loop, and scraping the enamel off the ends. (See Batteries and Bulbs Teacher's Guide for more details.) There is no commutation for this loop. Why it works has yet to be clearly formulated, and some electrical engineers have told us it will not work.

ISSN:0031-9228    

DOI:10.1063/1.3070890

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Take a spring, stretch it an inch or two, and imagine the force exerted by it. You will have no difficulty with this problem, and a layman or child will have no difficulty either, especially if you use the term “pull” instead of “force” in your question. Now take a second similar spring, hook it to the first one, and stretch the combination until each spring is extended to the same distance as the single spring before. When you then ask about the pull, most nonphysicists will state that it is obviously twice what it was before, because there are two springs instead of one. Try to convince them that the force has the same magnitude as before, because each spring is stretched by the same amount! How would you proceed?

ISSN:0031-9228    

DOI:10.1063/1.3070891

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

One evening not long ago I stood in the Nepalese town of Panga talking with a group of its citizens. For two hours or more I had been inquiring about their views of nature and of man's relation to nature, and our discussion had ranged widely over the world of familiar phenomena from rice planting to cosmology, from rainbows to moon and planets. Now as I was about to leave, we had stepped out into an enchantingly beautiful night. The houses across the square and the temple at its center were silhouetted against a brilliantly jewelled velvet black sky. Here and there a little mustard‐oil lamp offered a flickering challenge to the darkness, but there was no glare of street light or neon sign. Now and then a child's voice or the murmur of a conversation somewhere accentuated the quiet of the night, but there was no sound of vehicles or sirens or other machines of civilization, and we stood silent ourselves while enjoying the night. Just as I turned to leave, a bright “Echo” satellite appeared from behind the pagoda and swept in a slow silent arc across the sky. We watched it for several moments before I took leave and departed for my lodgings in the city.

ISSN:0031-9228    

DOI:10.1063/1.3070892

出版商:AIP    

年代:1972

数据来源: AIP