ABSOLUTE UNITS AND THE RELATIVITY PRINCIPLE 
By Granvile A. Perkins 1 
Of the Bureau of Science, Manila 
The Relativity Principle, announced by Einstein in 1905, 2 to 
the effect that if we have any absolute uniform velocity through 
space we cannot possibly determine it or even detect its exist- 
ence by the measurement of any known physical quantities, is 
inconsistent with the nineteenth century ideas of a stationary 
ether. It is even considered to be incompatible with our in- 
tuitions regarding time and space. In spite of these facts, it 
is generally conceded that the Relativity Principle is a logical 
conclusion from a mass of experimental evidence. It is further 
unquestionable that Minkowski, 3 4 and others following him, have 
been able to give a more complete mathematical form to the 
known physical laws by the use of four-dimensional coordinates 
instead of the usual three-dimensional space which corresponds 
to our intuitive ideas. 
The Relativity Principle has firm foundations, but certain 
applications which the “relativists” have made of it have not 
been universally accepted. They claim that “the phrase ‘ simul- 
taneous events at different points’ has no meaning until the 
velocity of those points is stated.”* This would not be so serious 
in itself, but they proceed to deduce from this alleged fact that 
we cannot possibly have any absolute units of length, time, or 
mass, and devise complicated “clock” and “light-signal” systems 
for defining various units of “times.” Crehore 5 and others have 
pointed out the absurdity of such ideas, and the present paper 
1 Prom an address before the Freer Club, Manila. Received for publica- 
tion April 15, 1921. 
2 Einstein, A., Ann. d. Physik. 322 (1905) 891. 
“Minkowski, H., Raum und Zeit, Phys. Zeit. 10 (1909) 104; cf. Cunning- 
ham, E., Relativity and the Electron Theory, London, Longmans, Green 
& Co. (1915) ; cf. also Einstein A., Ann. d. Physik. 354 (1917) 769. 
4 Cunningham, E., op. cit., 29 ; cf. alsoi Eddington, A. .S-, in the relativity 
symposium in Nature 106 (1921) 781-813. This interesting collection 
of articles came to the writer’s attention after the present paper went 
to press. 
5 Crehore, A. C., The Mystery of Matter and Energy. New York, Van 
Nostrand Co. (1917) 51. 
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