Water Mains to Be Used in Einstein Test

Water Mains to Be Used in Einstein Test

Two Chicago scientists, Prof. Albert A. Michelson and Henry G. Gales, physicists of the University of Chicago, intend to utilize a rectangle of air tight water mains to test the theory of Professor Einstein on relativity. The rectangle is under construction near Clearing and West 65th Streets, in Chicago. It will be 1,800 feet long and 1,200 feet wide.

Extent of the preparations may be inferred from the fact that the 7,200 feet of water mains weighing 300 tons are being laid, and seven tons of lead are being used to make the joints air tight. Cost of the work will include $7,500 for labor, and $1,600 for a 40-horse power pump to create a 28 1/2-inch vacuum.

In a portable garage, within which one corner of the rectangle will lie, there will be set up an arc-light, which is to throw through the pipes within a closed circuit two beams of light, traveling in opposite directions and caught and passed on by mirrors at each corner. A double length of pipe forms one side, making possible a check on the results.

The object of the experiment is to determine whether the two beams of light require exactly the same time to complete the circuit. The system of mirrors at the four corners of the rectangle constitutes an interferometer, which is one of the noted inventions of Professor Michelson—and makes it possible to compare the time required for the two beams of light to make the circuit.

If no difference in time of the rival beam is perceived it will be evident that light is not affected by the earth’s rotation. According to the Einstein thory, one beam should travel around the circuit in slightly less time than the other.

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