The appearance of a four-dimensional world is due to Minkowski. Einstein showed the relativity of the familiar quantities of physics; Minkowski showe… - Arthur Eddington

Let us begin with the fine-structure constant. ... The fine-structure constant is really the ratio of two natural units or atoms of action. ... We obtain action when we multiply energy by time. ... We are challenged to find a unified theory of electric particles and radiation in which the electrostatic type of action and the quantum type of action are traced to their source.

Spherical space is not very easy to imagine. We have to think of the properties of the surface of a sphere — the two-dimensional case — and try to conceive something similar applied to three-dimensional space. Stationing ourselves at a point let us draw a series of spheres of successively greater radii. The surface of a sphere of radius r should be proportional to r²; but in spherical space the areas of the more distant spheres begin to fall below the proper proportion. There is not so much room out there as we expected to find. Ultimately we reach a sphere of biggest possible area, and beyond it the areas begin to decrease. The last sphere of all shrinks to a point — our antipodes. Is there nothing beyond this? Is there a kind of boundary there? There is nothing beyond and yet there is no boundary. On the earth's surface there is nothing beyond our own antipodes but there is no boundary there.

I believe that there are 15,747,724,136,275,02,577,605,653,961,181,555,468,044,717,914,527,116,709,366,231,425,076,185,631,031,296 protons in the universe and the same number of electrons.