490 Prof. Q. Majorana : Theoretical and 



would be gradually absorbed, as in the case of light in its 

 propagation through a not perfectly transparent medium : 

 Newton's Law would only be exact in the first approxi- 

 mation. 



Consequences of the Hypothesis of Absorption. — The first 

 consequence would be the knowledge of the true mass, and 

 of the apparent mass. The true mass would be that property 

 of the mass to which the attractive force is proportional, if 

 it is reduced in very small particles. The apparent mass is, 

 on the other hand, the apparent value that the true mass 

 assumes in consequence of the gradual absorption. 



In order to respect the principle of the conservation of 

 energy, it would be required, furthermore, to admit that 

 any kind of matter is gradually transforming itself. This 

 would be analogous, so to speak, to what happens with 

 radium, with the difference that for this substance the 

 transformation lasts some thousands of years, whilst for 

 every one of the other known substances, the transformation 

 would last enormously longer. 



Another consequence might be deduced : since the force 

 of gravitation is produced by an energical flux that has been 

 absorbed, and as the energy cannot be destroyed, it ought to 

 transform itself, into heat, for instance. Therefore matter 

 subjected to gravitation is heated ; this fact would give a 

 new explanation of all the solar heat or of a part of it at 

 least. Furthermore, the hypothesis might be kept in mind 

 when considering the fact, which is nearly certain, that 

 there are no non-luminous stars of great dimensions in the 

 sky ; ponderable matter ought to heat itself if condensed 

 into little space. 



It is, however, with the utmost reserve that I state the 

 hypothesis of the energetic character of the force of gravi- 

 tation ; and if considerations that I do not detect at present 

 should arise in the future and make me judge it erroneous, I 

 should withdraw it. 



I rather consider as probable, and in fact, after some 

 experiments that I shall describe as certain, the hypothesis 

 of gravitational absorption. 



Analytical Researches. — In order to be able to establish a 

 plan of experiments with the purpose of verifying the 

 hypothesis of absorption, it is necessary to consider this 

 hypothesis analytically. A physical quantity, sui generis, 

 can now be defined and called flux of gravitational action ; it is 

 not yet necessary to connect the notion of this quantity with 

 the notion of energy. Let us suppose a material particle dm 

 so small that its inner gravitational absorption might be 



