(6 of 10)
To meet the challenges, the resilient Hoyle has proposed a steady-state variation. In his steadily expanding universe, there could be "bubbles" in which expansion or contraction sometimes takes place. The earth just happens to be in one of the expanding bubbles, he suggests, which accounts for the disturbing quasar observations.
Mere Peanuts. Quasars have actually presented a greater challenge to physicists, who have been working overtime to deal with the implications of Schmidt's discoveries. How can such relatively small bodies generate enough light to be seen billions of light-years away? Where did the energy come from? Early observations suggested that the quasars were only a fifth or as little as a hundredth the size of an average galaxy, which is about 100,000 light-years in diameter. Yet the quasars' light is as much as 100 times more brilliant than light from an ordinary galaxy—despite all of its 100 billion glowing stars—that is the same distance away.
Particularly perplexing is the fact that the light output of many quasars has been observed to vary over cycles as short as three months. To some astron omers, this means that some of the quasars may be as small as 90 light-days in diameter—a distance of 1.5 trillion miles, which is mere peanuts by cosmological standards. If these quasars were much larger, the light and radio waves from various parts of them would arrive at the earth at different times, smearing out the variation and making it unobservable.
The necessity of explaining the prodigious outpouring of energy from such small bodies has generated some fantastic intellectual inventions, some of which may yet turn out to be accurate. Fred Hoyle and a California Institute of Technology colleague, William Fowler, have suggested that quasars might well be massive superstars whose nuclear fires have died down because of the depletion of their hydrogen fuel. Such stars, they say, would begin to collapse, contracting under their own gravity. And the tremendous energy released by matter falling toward the star centers might well be of a magnitude that could explain a quasar's fierce radiation.
Hoyle and Fowler are disputed by other scientists who maintain that gravitational collapse of such a very massive star would quickly result in a mind-boggling consequence: the Schwarzschild singularity. In 1916, German Astronomer Karl Schwarzschild used Einstein's equations to demonstrate that very massive bodies can literally gravitate themselves out of the observable universe. When such stars contract to a critical size during catastrophic collapse, Schwarzschild calculated, their gravity becomes so strong that it prevents any matter, or even radiation, from escaping into space. As a result, the stars simply disappear from view; they would be detectable only by their tremendous gravitational force.