THE PRESIDENTIAL ADDRESS. 5 
conception of the basic structure of the world. The transformation of 
the concept of space, owing to the injection into it of time, has destroyed 
the old passive homogeneous notion of space and has substituted a 
flexible, variable continuum, the curvatures and unevennesses of which 
constitute to our senses what we call a material world. The new concept 
has made it possible to construe matter, mass and energy as but definite 
measurable conditions of curvature in the structure of space-time. 
Assuming that electro-magnetism will eventually follow the fate of 
gravitation, we may say that space-time will then appear as the scientific 
concept for the only physical reality in the universe, and that matter and 
energy in all their forms will have disappeared as independent entities, 
and will have become mere configurations of this space-time. This will 
probably involve an amplified concept of space-time. THinstein has 
recently indicated that for further advance a modification in our space- 
time concept will become necessary, and that the additional element of 
direction will have to be incorporated into it. Whatever change may 
become necessary in our space-time concept, there can be no doubt about 
the immense possibilities it has opened up. 
I pass on to an even more revolutionary recent advance of physics. The 
space-time world, however novel, however shattering to commonsense, is 
not in conflict with reason. Indeed, the space-time world is largely a 
discovery of the mathematical reason and is an entirely rational world. 
It is a world where reason, as it were, dissolves the refractoriness of the 
old material substance and smoothes it out into forms of space-time. 
- Science, which began with empirical brute facts, seems to be heading for 
the reign of pure reason. But wait a bit; another fundamental discovery 
of our age has apparently taken us beyond the bounds of rationality, 
and is thus even more revolutionary than that of space-time. I refer to 
the Quantum theory, Max Planck’s discovery at the end of the nineteenth 
century, according to which energy is granular, consisting of discrete 
grains or quanta. The world in space-time is a continuum ; the quantum 
action is a negation of continuity. Thus arises the contradiction, not 
only of commonsense, but apparently also of reason itself. The quantum 
appears to behave like a particle, but a particle out of space or time. 
As Sir Arthur Eddington graphically puts it: a quantum of light is large 
enough to fill the lens of a hundred-inch telescope, but it is also small 
enough to enter an atom. It may spread like a circular wave through the 
universe, but when it hits its mark, this cosmic wave instantaneously 
contracts to a point where it strikes with its full and undivided force. 
