6 THE PRESIDENTIAL ADDRESS 
relative size. Yet even these very reasonable requirements cannot 
usually be satisfied in a single map ; the only exception is when the 
map is to contain only a small part of the whole surface of the globe. 
In this case, and this only, all the qualities we want can be combined 
in a single map, so that we simply ask for a map of the county of 
Surrey without specifying whether it is to be a Mercator’s or ortho- 
graphic or conic projection, or what not. 
All this has its exact counterpart in the map-making task of the 
physicist. ‘The Newtonian mechanics was like the map of Surrey, 
because it dealt only with a small fraction of the universe. It was 
concerned with the motions and changes of medium-sized objects— 
objects comparable in size with the human body—and for these it was 
able to provide a perfect map which combined in one picture all the 
qualities we could reasonably demand. But the inconceivably great 
and the inconceivably small were equally beyond its ken. As soon 
as science pushed out—to the cosmos as a whole in one direction and 
to sub-atomic phenomena in the other—the deficiencies of the New- 
tonian mechanics became manifest. And no modification of the 
Newtonian map was able to provide the two qualities which this 
map had itself encouraged us to expect—a materialism which ex- 
hibited the universe as constructed of matter lying within the frame- 
work of space and time, and a determinism which provided an 
answer to the question “ What is going to happen next ?’ 
When geography cannot combine all the qualities we want in a 
single map, it provides us with more than one map. Theoretical 
physics has done the same, providing us with two maps which are 
commonly known as the particle-picture and the wave-picture. 
The particle-picture is a materialistic picture which caters for 
those who wish to see their universe mapped out as matter existing 
in space andtime. ‘The wave-picture is a determinist picture which 
caters for those who ask the question “‘ What is going to happen 
next?’ It is perhaps better to speak of these two pictures as the 
particle-parable and the wave-parable. For this is what they really 
are, and the nomenclature warns us in advance not to be surprised 
at inconsistencies and contradictions. 
Let me remind you, as briefly as possible, how this pair of pictures 
or parables have come to be in existence side by side. 
The particle-parable, which was first in the field, told us that the 
material universe consists of particles existing in space and time. 
It was created by the labours of chemists and experimental physi- 
cists, working on the basis provided by the classical physics. Its 
time of testing came in 1913, when Bohr tried to find out whether 
the two particles of the hydrogen atom could possibly produce the 
highly complicated spectrum of hydrogen by their motion. He found 
a type of motion which could produce this spectrum down to its 
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