174 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
This result is intellectually very satisfactory. In fact, it agrees 
with a fundamental principle of cosmological theory, a principle 
which has been postulated by theorists for no other reason than its 
appeal to our sense of order and the fitness of things. This principle 
states that the universe, on a grand scale, will appear much the same 
from whatever position in space it may be viewed or explored, This 
principle of cosmology is satisfied, therefore, if the nebulae are not 
assumed to be receding. 
We next investigate the consequences of assuming the red shift to 
be due to a real velocity of recession of the nebulae. The dimming 
factor must now be applied in estimating distances, with the result 
that the most distant cluster is actually about 13 percent fainter than 
it would be if it were stationary. The scale of distances is thus 
altered, so that when we make our space survey to find out how the 
nebulae are distributed it turns out that they are no longer scattered 
uniformly. The number per unit volume increases steadily with 
their distance away from us. Here is a result which is intellectually 
very disquieting. The cosmological principle of no favored position 
is violated. We might be willing to accept this violation if it went 
the other way, that is, if the density of nebulae decreased with dis- 
tance. Then we would conclude, very happily, that we had discovered 
another super-supergalaxy, another big matter bunch to put out on the 
right-hand end of our linear lay-out. No such interpretation can be 
given when the nebulae are found not to thin out at big distances, but 
actually to become more dense in numbers. 
It may seem obvious to the layman that we ought to discard the 
idea of an expanding universe. It makes us worry about the short 
time which has elapsed since the original cosmic explosion occurred ; 
it bothers us with an increasing density of matter as we proceed far- 
ther and farther into the depths of space; and the only evidence we 
have to go on is a series of pictures, rather hazy, smeary pictures, in 
fact, with a light patch shifted too far to one side. 
The physicist and the astronomer, unfortunately, cannot treat these 
fuzzy pictures in such a cavalier manner. There is no denying the 
existence of the shifted light patch in the pictures, hazy though it 
may be. There is no denying the fact that all such similar shifts of 
color have been explained satisfactorily by the Doppler effect and by 
the Doppler effect alone. One is reminded of the saying of the old 
colored man, whose years of experience had developed a certain ripe 
philosophy of life. “It ain’t so much what you don’t know that gets 
you into trouble, it’s what you do know and ain’t so!” 
There are several ways, more or less unsatisfactory, of escaping 
from the dilemma of the expanding universe. The first way is not 
