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Show no LIGHT VERSUS GRAVITATION (By Garrett P. Scrviss.) A most fascinating glimpse into the mysteries of the universe in furnished by the recent studies of Director Campbell of the Lick observatory, of the motions of the stars In the line of sight. It has long been known that some stars are approaching the sun, while others -are receding from it, Tho motions are not directly toward or away from lis:, but aro directed at various angles to our lino of sight. But the astonishing thine; now beginning begin-ning to be revealed is that the speed of these motions appears vto depend upon the age of thp stars The oldor stars travel faster than the younger. The relative age is determined by tho spectroscope. Tho sun appears to bo iii-iiJin.fl niifl an ii i"ii.n iq T; a middle aged star Tho velocity of J Its motion Is such as to carr- it through space in a northerly direction direc-tion about a million miles per day The discovery, for there appears 1 to be little doubt of its substantial J; correctness, that the speed of the ) stars is proportional to their age, I touches, In a manner which may not at first glance be obvious, upon tho question of the constitution of the universe uni-verse In which we live. Lot us see how thus is, . If the motion of the stars varies not only with their mass and the-.r ! nearness to some attracting center, but also with their age the only ex- j planatlon that offers Itself Is that there must be something in the condition con-dition of the younger stars which renders ren-ders them less subject to gravitational gravitation-al effects than the older ones are. : They must be In such a state that J the'pull of gravitation upon them is i less effective. This can be accounted for by the supposition that they have been subject to this pull for a shorter 4 time, depending upon the period 1 which has elapsed since they began i1 to condense. Before condensation, j while they are still In a purely neb- J ulous state, it would seem that gravitation gravi-tation was unable to set them in motion. mo-tion. Now this is explicable ly the hy- - pothesls that nebulous matter is so "'. finely divided that the radiation pressure upon it Is equal, as It must j1 be opposite, to the gravitational pull. I Many readers will recall that it has f recently been shown that the radla- tion from the sun Is capable of driv- ! Ing off, or pushing away, minute particles par-ticles of matter in space, say the hun- ' dredth thousandtn of an inch in di- t ametcr, In spite of th fact that its ) (the sun's) gravitation is all the time i drawing upon such particles This I phenomenon is called the ''pressure of j light," and It has been invoked to ex- ,, plain the fact that comets tails always al-ways point away from the sun f If, then, we suppose that a nebula j- In a scattered state Is prevented from ll moving under tho gravitational pull ft of the stars around it because their I radiation pressure counteracts their f atti action, we have the explanation of i the fact that the great amorphous i , nebula in Orion appears to be stand- I, ing still in space, although the stars j about It are in swift motion And we can likewise explain tho fact that the i younger stars move less rapidlv than Ju the elder ones because they have, rcl- '91 atlvoly speaking, only recently been ;'H condensed to such an extent that the ,B gravitational pull upon them exceeds S tho effects of ihe pressure of radia- ' tlon. As time goes on their speed M should increase, just as the stone m falls' faster the greater the holght I from which it has been dropped, and a the longer It has been in motion. 1 The moral of this is that we must now hegiu to take into account some- i thing else besides Newton's law of v gravitation. In studying the origin, if ; condition, and tho future history of $ the universe. Light pressure looms 4 up as one of tho master forces at work In the cosmos. ii |