Word: redshift
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Dates: during 1930-1939
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...miles per second. The light from these nebulae is shifted toward the red end of the spectrum and ordinarily, such a shift indicates receding velocity. But the speeds are so big that many astronomers consider the Expanding Universe may be an illusion, have sought some other cause for the redshift in the spectrum. A decrease in Planck's constant h (energy of light multiplied by its vibration period) might be such a cause. Last year Britain's potent Theorist Paul Adrien Maurice Dirac suggested that the gravitational constant and certain others were dependent...
...Astronomer Edwin Powell Hubble. Beginning in 1928, Hubble and his coworker, Milton LaSalle Humason, showed that the light from the most distant nebulae (clouds of stars) which he could photograph in Mount Wilson's giant telescope was shifted far toward the red end of the spectrum. Such a redshift is observed in the light of a star known to be retreating from Earth, so it was assumed that the distant nebulae were retreating in all directions. On these observations, and on the theoretical expanding universes formulated by de Sitter and Lemaitre before any observations were made, the case...
...Arthur has never lost his enthusiasm for this cosmic soap bubble. But the speeds indicated by the amount of redshift, some of which now equal 25,000 miles per second, have made many astronomers doubt. Other causes for the redshift were suggested, such as cosmic dust or a change in the nature of light over great stretches of space. Two years ago Dr. Hubble admitted that the expanding universe might be an illusion, but implied that this was a cautious and colorless view. Last week it was apparent that he had shifted his position even further away from a literal...
...true position. The other statement was that light moving against a gravitational field should be "stretched" by the strain-i. e. suffer an increase of wavelength, which should displace spectrum lines toward the red (long wavelength) end. Thus, light winging away from a heavy star should show a definite redshift. Obstacle to confirmation was that another and unrelated spectrum shift existed (the Doppler effect), due to the motion of the star away from or toward the observer. Last week the same Dr. Trumpler announced that he had solved the difficulty by measuring the redshift of nine "O" stars (hottest, brightest...
This is a reductio ad absurdum not only for common sense but for the theory of Relativity. Timidly at first but more boldly of late, some astronomers have suggested other possible causes for the redshift, viz. cosmic dust scattered through space or a slowing of light's velocity after millions of years of travel. Once as fervid a believer in the expanding universe as Sir Arthur Eddington, Dr. Hubble was ready last week to admit that it might be an illusion. "The cautious observer," said he wryly, "refrains from committing himself to the present interpretation and employs the colorless...