Word: redshift
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...distant than astronomers had previously believed. That, in turn, meant the expansion had been going on longer than anyone thought, and that the age of the universe was at least 16 billion years, or roughly 4 billion to 6 billion years older than earlier estimates. Even more important, the redshift measurements of nearby galaxies gave no indication of any significant gravitational slowdown in the outward rush of the galaxies. "It's a terrible surprise," says Sandage, who for years had been leading proponent of the idea that the universe would eventually close in on itself...
...shock. Astronomer Greenstein promptly shelved his own unpublished quasar theory, admitting that "if it weren't for Maarten, I could have been caught with my scientific trousers down." Instead, he turned to a spectrogram that he had taken from quasar 3C 48 and - using Schmidt's redshift key - discovered that 3C 48 was re ceding even faster than 3C 273. By Hubble's law it appeared to be some 4 billion light-years away...
Speeding Clusters. Using the "redshift" (light from a galaxy speeding away from the earth shifts in proportion to its speed toward the red end of the color spectrum), Sandage studied the speeds of six clusters of galaxies about a billion light-years away. According to Hoyle. the clusters should be moving at a speed in direct proportion to their distance from the earth. But recent calculations show that the clusters are moving about 10,000 kilometers (6,200 miles) per second faster than Hoyle's prediction...
Your Science article [TIME, June 25] on the work of Humason and the redshift of the nebular spectra is excellent and is interestingly written. However, the story tends to give an inaccurate idea by saying that this effect was "first discovered by Hubble . . . and that on it he based his startling theory of the expanding universe." In reality, I believe you will find that the redshift was first observed by V. M. Slipher of Lowell Observatory. Hubble, however, was the one to notice the law connecting the amount of the shift and the distance of the nebulae...
Some skeptical cosmologists do not admit that the redshift necessarily means that the nebulae are moving. Perhaps, they say, their light "gets tired," losing some of its energy during its tremendous journey through space. Since loss of energy would lengthen the wave length of light, a sufficient amount of fatigue would account for the shift toward the red in the spectrum...