Layzer Proposes Theory Explaining Why the Night Sky Is Not Bright
David R. Layzer '45, professor of Astronomy, has proposed a new theory to describe the state of the universe "long before stars or galaxies existed."
In addition, the theory may shed some light on the age-old question of why the sky is black at night, rather than gray or as bright as the sun itself.
Layzer argues that matter first existed as unorganized dust. In this early state the universe was only moderately warm. As it lost energy into space, however, it began to make up its losses by gravity. Pressure built up, and its temperature rose.
After approximately 10,000 years, his theory continues, temperatures reached approximately one million degrees and the mass began to glow with intense radiation. Later, as the dust again cooled and stars began to form, the energy was dissipated throughout the universe.
Scientists at Bell Telephone Laboratories last year detected a band of microwave radiation from a specific celestial source. It is this radiation, Layzer argues, that in the degraded remnant of that energy which this pressure produced billions of years ago.
Layzer's theory also helps resolve what is known as Olber's Paradox on the night- time sky.
According to Olber, Layzer said yesterday, the light produced by faraway stars should make the night sky intensely bright and hot. Obler reached this conclusion after observing a "shell" of stars at a given distance from the earth. While the brightness of the stars will diminish with the square of their distance, Layzer said. The area of the shell--and thus the number of stars on it--will go up it the same rate.
As a result, the total amount of light reaching the earth will be fantastically large. But, as any observer can tell, the sky is dark, and some part of Olber's argument must therefore be incorrect.
Previous attempts to resolve the paradox, Layzer said, focused on present conditions in the universe. Some concluded that stars were rapidly receding from the earth and that light was shifted into an invisible part of the spectrum. Others argued that stars have only a limited life-time and that, at a given moment, only a small number will emit visible light.
Layzer, however, argues that any light from stars less than a billion years old would make an "insignificant" contribution to the brightness or darkness of the sky. The microwave energy from the early universe, he said, is a far more important factor, and only because this is so dispersed and weak is the sky dark.
Astronomers have begun to question his theory, Layzer said. One alternative explanation states that temperatures in he early universe were even higher, approaching a billion degrees.
If the alternate theory were true, Layzer said, the intensity of microwave radiation at 300 billon cycles per second should be relatively high. His own concept predicts a much smaller amount. A number of scientists at M.I.T. are presently designing a rocket to measure this energy in the vacuum of space and settle the controversy