A Better Eye

Man's best window on the universe is the 200-inch Hale telescope on Palomar Mountain. It is a good window, but not good enough to satisfy the astronomers. It sees only a billion light-years into space, and the universe is a great deal bigger than that. The astronomers would like to see more.

There is not much point in building a big brother for the Hale telescope. Even if its mirror were made twice as wide (a monstrously difficult and costly undertaking), it would see only twice as far into space. It might not see even as far as that; one of the Hale's great difficulties is the faint "shine" of the night sky, which fogs its photographic plates before they can catch the images of extremely distant objects. A bigger Hale-type telescope would suffer even more from sky shine.

Last week the Carnegie Corporation granted $50,000 for a fresh approach to studying the universe. Urged on by Dr. Vannevar Bush of the Carnegie Institution, scientists will try to make telescopes work better without getting bigger.

The present system of focusing light from the heavens on a photographic plate is notoriously inefficient. Only about 2% of the photons (particles of light energy) leave an impression on the photosensitive emulsion. The other 98% are lost.

One way to reduce this waste has been tried with some success by Astronomer Andre Lallemande of Paris (TIME, Aug. 13) 1951). Instead of using a photographic plate direct, he focused the light on a "photoemissive surface" of antimony and cesium, which gives off electrons when struck by light. The electrons jump to a photographic plate and expose it more efficiently than direct light does.

The trouble with this system is that the plate and the photoemissive surface have to be kept close together in a vacuum (electrons do not pass through glass), and gases from the plate quickly spoil the sensitive, metallic surface.

Dr. Bush and his collaborators have various plans for getting around this difficulty. Perhaps, they think, the electrons from the sensitive metal could be "stored" on a surface that gives off no gases. Later they could be released, either to impress a strong image on a photographic plate, or to be scanned and displayed on a screen after the manner of television. The scanning system would not only yield a much stronger image with the same amount of light, it might even eliminate the fogging due to sky shine.

The more optimistic astronomers believe that some system of this sort would multiply the effectiveness of any telescope about 50 times. The Hale telescope, electronized, might see the edge of the universe, if the universe has an edge.

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