Astronomy: Toward the Edge of the Universe

  • Share
  • Read Later

The announcement said that Astronomer Maarten Schmidt of Caltech had discovered a quasar (quasi-stellar radio source) racing away from earth at 80% of the speed of light. That brief observation last week surely marks a significant milestone in the expanding reach of modern astronomy. Since speed is related to distance, the speed of Schmidt's quasar makes it by far the most distant object ever identified. Even more important, discovering the quasar meant that Dr. Schmidt had refined a delicate technique that will almost certainly find still more distant objects and lead man close to the edge (if there is an edge) of the observable universe.

Fast & Far. Quasars were first recognized as astronomical curiosities when, unlike the ordinary stars they resemble, they showed up as the sources of enormous amounts of radio energy. Then Dr. Schmidt studied spectrograms of their light and demonstrated that it had shifted far toward the red wave lengths —proof positive that quasars are not only incredibly far off but are speeding away still farther, carried along by the rapid expansion of distant parts of the universe.

With every new observation, the mystery deepened. Quasars turned out to be by far the most brilliant objects in the universe, shining with the light of from 50 to 100 galaxies, each containing 100 billion stars as bright as the sun. Where did all the energy come from? Searching for answers, Dr. Schmidt and his colleagues pored over spectrograms which showed quasar light separated into its various wave lengths. They knew that the most distant fast-moving bodies should show spectrogram lines of far ultraviolet light whose waves had been lengthened so much in their shift toward the red that they would appear in that part of the spectrum where the much longer waves of visible light are normally found. So they catalogued all possible kinds of ultraviolet that might conceivably come from a quasar and looked for characteristic patterns in their faint spectrograms. At last they found a quasar, 3C-254, whose spectrum showed five clear lines. All except one of them had been identified in earlier-found quasar spectrograms; the fifth, which lay deeper in the ultraviolet, could now be identified by its relation to the other four.

Tripled Wave. Step by painful step Schmidt's search identified spectrogram lines and unlocked the spectral secrets of five new quasars. The most distant of them, 3C-9, showed signs of a kind of ultraviolet which comes from the sun in considerable quantities but is absorbed by the earth's atmosphere. It had never been photographed before by surface observatories. In the 3C-9's spectrum, its wave length had been more than tripled by shifting toward the red. It showed as an easily photographed blue and proved that the quasar's speed is 149,000 miles per second, 80% of the speed of light.

In last week's announcement five new quasars were listed, their speeds varying upward from 93,000 miles per second. What this means in actual distance Dr. Schmidt is not quite sure. He is certain, however, that they are the most distant objects so far identified, even though man's knowledge of the outer fringes of the universe is too uncertain for making hard and fast measurements. Out among the quasars, space itself may have unfamiliar properties.

  1. Previous Page
  2. 1
  3. 2