From time to time, what appear to be longstanding natural barriers, such as the four-minute mile and the sound barrier, break under the pressure of continued effort.
Researchers have found the oldest and most distant object in the universe, a quasar 13.8 billion light years away, in one of a sudden series of finds that have broken what looked like a natural limit to astronomical age and distance.
For decades, poorly understood but powerfully radiating objects called quasars, thought to be massive black holes, appeared to occur in a certain natural range of ages and distances.
The age and distance is determined by measuring the wavelength of the light from the quasar. According to astronomical dogma, the older and more distant an object, the faster it is moving from Earth. The faster it moves, the more its light waves appear stretched to an observer on Earth. This stretching is called red-shift.
The greatest stretching of light seen before this year was between three and four times the original wavelength. From 1972 to 1986, discoveries fell in the range from 3.5 to 3.8 times longer than their original wavelength. It seemed that a factor of four was a natural barrier for red-shift.
But, in a burst of discoveries this year, six quasars have been found with light stretched to a greater red-shift.
The greatest, 4.43, was announced in an article in the Dec. 3 issue of the British journal Nature by collaborating groups led by S.J. Warren, P.C. Hewett and M.J. Irwin of the Institute of Astronomy in Cambridge, England, and Patrick S. Osmer of the Kitt Peak National Observatory in Arizona.
A red-shift of that size means the object being observed is about 92 percent as old as the universe. Although the age of the universe has long been estimated at around 15 billion years, more recent estimates put it closer to 13 billion years. Whatever the universe's age, the quasar's age remains 92 percent of it. This means that the quasar seen today was actually in existence very early in the history of the universe. It may long since have died.
Astronomers have generally found that the farther away they look, the more quasars they see. This is taken to suggest that there were more quasars in the universe long ago than there are now.