L.S.C. 4 Proes. of the Asiatic Soc. of Bengal. [N.S., XVIII, 
seem to be the inadequate if not exactly inappropriate illus- 
trations of the theory given instein himself. 
The Principle of Relativity, and the Special and General 
theories as elaborated by Einstein, must be familiar to most 
of my audience. I do not propose to attempt any further 
as wholes. But here and there in those explanations we meet 
with definite concrete statements of supposed facts, which 
if closely examined or followed out seem unacceptable to an 
ordinary intelligence. I feel that these should be stated, as 
I cannot believe that I alone am unfortunate in havin 
encountered these stumbling-blocks in the way of accepting 
the theories as credible, 
I shall proceed at once to focus on one or two points 
only, to exemplify the above. Let me refer first to Einstein’s 
illustration of what he speaks of as the ‘ relativity of simul- 
taneity ’: Lightning has struck the railway line at two distant 
points, and, in answer to Einstein’s demand for a method of 
proving or disproving the simultaneity of the two flashes, 
he supposes a reply that involves placing two mirrors at the 
middle point, so arranged that the two flashes could be seen 
together. Then, simultaneity he more or less grudgingly 
agrees would be established if the two flashes were seen at 
not simultaneous. Hence, he states, simultaneity of two 
events is different for two observers, one stationary and one in 
movement—that in fact simultaneity is a relative matter. 
This fictitious experiment (as little to the point, as it seems 
to me, as it the flash and report of a gun had been taken in 
illustration) colours all the arguments for the Special theory 
of Relativity; and hence we get figuring in the equations the 
ever-appearing ratio —- where v is the velocity of the body 
2 
and ¢ that of light. 
Now, in spite of my wish not to be dogmatic, I think it 
may well be a question for any person here, or indeed for any 
matriculation student or intelligent schoolboy, to ask whether 
Einstein has not woefully (if not wilfully) confused an event 
with the transmission of the effects of that event to a distant 
point by the medium of light. The lack of simultaneity of the 
two flashes perceived in the two mirrors by the person in the 
moving train seems to have nothing to do with the two events 
themselves, which were either simultaneous or they were not 
so. I think that without further words one may decide that 
to get or prove simultaneity in any such happenings as two 



