Is the speed of light decreasing? Is this one supposedly stable cosmic yardstick in a varying, relativistic universe itself undergoing shrinkage? M.E.J. Gheury de Bray, writing in L'Astronomie, the official journal of the Astronomical Society of France, ventures the daring speculation that the velocity of light is decreasing at such a rate that each year it darts through space about four kilometers a second slower than it did a twelve-month earlier. He cites in support of his claim the results of determinations of the velocity of light during a period of over three-quarters of a century, of which only one, made in 1855 with apparatus which may have been faulty, is really notably out of step.
The velocity of light is usually stated as 186,000 miles, or 300,000 kilometers, per second, which is fast enough to take it seven times around the earth while the clock ticks once. But for exact work in astronomy, physics, and other sciences, determinations to fill out the three blank ciphers usually ignored in ordinary statements are desired, and these have been made a number of times. The most recent research was that of Dr. A.A. Michelson of the University of Chicago, in 1926, which set the figure at 299,796 kilometers a second. This, according to M. de Bray, is the lowest velocity ever observed, but the new determination, on which Dr. Michelson is working now, should turn out even lower.
The planet Mercury, nearest to the sun of all the members of the solar system, turns once on its axis in 88 days, the same time that it takes to travel once in its orbit around the sun. The result is that it always keeps the same face to the sun, just as the moon always keeps the same part of its surface towards the earth. E.M. Antoniadi, famed planetary observer of the Meudon Observatory, at Meudon, France, has just completed a series of observations which indicate these facts and confirm the views of Schiaparelli, an Italian astronomer. M. Antoniadi has made his planetary observations with the great 33-inch refracting telescope of the Meudon Observatory.
| This gentleman from a circus midway is a very complete specimen of the modern tattooer's art. |
TimeLine Archives
