MODEEN IDEAS ON THE END OP THE WORLD JAUMANN. 215 



attractions of the planets are taken into consideration. Taking 

 these deviations into consideration, it is possible at present to calcu- 

 late to within a few seconds the positions of the sun, the moon, and 

 the planets a hundred years in advance. But to determine at a dis- 

 tance of millions of years the end of the Newtonian world enormous 

 mathematical difficulties must be overcome; indeed, it is a matter 

 concerning the problem of the stability of the planetary system and 

 of calculating whether the disturbing influences, weak but incessant, 

 which the planets exercise upon each other will nearly counteract 

 each other in time or will end by entailing the destruction of the 

 planetary system. 



Eminent scholars have always taxed themselves with resolving this 

 fundamental problem relative to the stability of the world. Laplace 

 and Lagrange showed, by means of an approximate calculation, that 

 the planetary system of Newton appeared to be stable. Poisson 

 demonstrated that by further refining the calculation later epochs 

 could be surveyed, in which greater and greater fiuctuations in the 

 form of the planetary orbits were present. Finally Poincare proved 

 that by carrying the calculation to its limit, a future time was dis- 

 closed in which the planets would experience unlimited, progressive, 

 so-called secular disturbances and, finally, some of them would fall 

 into the sun, and others lose themselves in the cold of cosmic space. 

 Thus, the planetary system of Newton has no stability, no internal 

 constancy. But the foregoing calculations were made on much too 

 favorable a basis. Cosmic space can not be empty, as Newton held. 

 Since it can transmit light, it must be filled with a medium, ex- 

 tremely tenuous and cold, called cosmic ether. The extreme vacuum 

 obtained in the laboratory, cooled to —170° C, presents a con- 

 siderable viscosity, which is only ten times inferior to that of the 

 normal air.^ Consequently, the cosmic ether must oppose to the 

 movement of the planets a very appreciable frictional resistance. 

 They must continually lose energy of motion; in addition to which, 

 the attractive action of the sun becoming more and more considerable, 

 the planets should describe orbits more and more narrow and should 

 end, in some millions of years, by precipitating themselves into it. 

 Thus, again, we have the " igneous " death of the earth. But that 

 end would be preceded by the destruction of the terrestrial organisms, 

 all being menaced by death from the cold, which would set in much 

 earlier. 



1 Thii5 extreme vacuum at —170° C. has the modulus of viscosity 2X10"^ c. g. s. To 

 overcome the resistance that the ether offers to our earth would require more than 

 150,000,000 horsepower. Meteorites must glow in the ether if their diameter be less than 

 50 cm. As a matter of fact, a glowing meteorite has been observed at a height of some 

 7S0 kilometers (above Sinope on Sept. 5, 1868, reported by G. von Niessl in Vei-handl. 

 d. naturforsch. Vereines in Briinn, vol. 17, p. 316, 1879), and even in the spectrum of the 

 comets when approaching perihelium (when their velocity is greatest) clear indications of 

 the glowing of solid bodies have been observed. 



