Science: Philosophy & Physics

Unlike political conventions, scientific conventions are assembled not to agree on a common program of action but to toss individual contributions into a hopper of common learning. The preoccupations of the American Philosophical Society, founded by Benjamin Franklin in 1743 for ‘”promoting useful knowledge,” concern almost every kind of science. Preoccupation of the American Physical Society, founded in 1899, is straightforward physics, let the philosophical chips fall where they may; but physics may include anything from the electrical conductivity of a safety pin to the fringes of the universe. Last week the American Philosophical Society assembled in Philadelphia and the American Physical Society convened in Chicago. Noteworthy topics discussed at the two meetings:

Deep Rays. Near Mohawk, Mich., the Seneca Copper Mining Co. has a mine shaft which slopes down at a 34° angle to a vertical depth of 1,600 feet. Volney C. Wilson, research assistant of the University of Chicago’s famed Arthur Holly Compton, worked for three months in the shaft with a cosmic ray recorder of his own design, containing four ionization tubes. These were arranged in line so as to exclude cosmic rays shooting down the open shaft, to catch only rays boring vertically through the rock. From the surface to 1,600 feet Mr. Wilson took measurements at 39 stations. The intensity diminished steadily as he descended, but at the bottom he was still getting a few rays of extraordinary penetrating power, at the rate of about eight per day.

These were said to be the deepest authentic cosmic ray recordings ever made. Mr. Wilson, believing that ordinary electrons or protons could not penetrate 1,600 feet of solid rock, came to the conclusion that the rays must be either neutrinos or X-particles, both relative unknowns. For although atomic physicists speak of neutrinos (small, uncharged particles with a mass less than that of an electron) as familiarly as a carpenter does of a tenpenny nail, they have never come to light experimentally. “X-particles,” although they have turned up experimentally (TIME, Nov. 29), have yet to be explained or understood.

Nuclear Capture. The atom consists of a tough, massive nucleus with one or more electrons spinning around it. For long years physicists assumed that an outside electron never fell into its own nucleus. At Ohio State University, Dr. Marion Llewellyn Pool bombarded silver with various projectiles, made it artificially radioactive. Thirty-five times more gamma rays than electrons spurted out of the radioactive silver. The only way Dr. Pool could explain this abnormally high ratio was by assuming that the nucleus had captured one of its own outside electrons.

Red-Shift Explained? Once enthusiastically propagated, the idea of a universe whose outer nebulae were rushing away from Earth in all directions has lately lost favor among astronomers. Evidence for the recession of the nebulae is that, when their light is broken up into a spectrum, certain lines are shifted far to the right, or red end of the chromatic scale. Smaller shifts of this sort have been observed in the spectra of comparatively nearby stars known to be moving away from the solar system.

If the universe is not actually expanding, there must be some other reason for the redshift of the nebular spectra. One suggestion is that photons of light “get tired” over the long journey of millions of light years and lose energy. This would increase the wave length, and shift the spectrum lines toward the red (longest visible wave lengths). Another suggestion is that Planck’s constant h (energy of light multiplied by its vibration period) is not really a constant although it involves the wave length of light and has been universally treated as a constant. A third suggestion was offered last spring by England’s brilliant Paul Adrien Maurice Dirac that the gravitational force of the universe is decreasing as a function of time. Perhaps stimulated by this idea, Dr. Ira M. Freeman of Chicago’s Central College last week offered calculations to show that a “decrease of the gravitational potential of all the matter in the universe” would act upon photons of light coming from distant nebulae in such a way as to account for the troublesome redshift.

Bottom Sampler. Sometimes in Earth’s history ocean bottoms have been thrust up to form dry land, but it appears that much of the present ocean floor has always been under water. For millions of years it has been covered with layers of sediment — mud from rivers, sand and gravel from glaciers, corpses of marine organisms dropped by changing currents and ocean climates. Dr. Charles Snowden Piggot of the Carnegie Institution invented a device for bringing up intact samples of this informative bottom several feet deep. Essential part is a “bit” ten feet long, some two inches in diameter. Above the bit is a sort of gun containing a charge of explosive. When this apparatus is lowered into the depths on the end of a cable, contact with the bottom trips a mechanism which fires the gun, driving the hollow bit straight down. When it is pulled up to the surface, it contains a slender core showing the sedimentation layers exactly as they lay before the gun was fired. Samples taken from the bottom off Newfoundland, Ireland, Cuba and Jamaica are being studied by the U. S. Geological Survey.

Parthenogenetic Merogony. Production of offspring from female cells unfertilized by males — parthenogenesis — is a commonplace in nature and in biological laboratories. Less common is merogony, which is fertilization by the male element of cell fragments not containing the hereditry-bearing female nucleus. Dr. Ethel Browne Harvey of Princeton combined the two by splitting egg cells of the sea urchin (a small, spiny creature) in a powerful centrifuge, then stimulating the fragments containing no nucleus with sea water having a higher diffusion pressure than the cell liquid. Cell fragments so treated, said Dr. Harvey, “throw off normal fertilization membranes, division takes place, cleavage follows cleavage in a fairly orderly fashion. More and more cells are formed, until there is a group of some 500 cells, forming a fairly normal blastula (early embryonic form). Some of these activated non-nucleate eggs have lived for four weeks. The normal unfertilized egg with a nucleus lives only a day or two.”