To obtain a greater degree of permanence the time symbols of oral speech had to be converted into the space symbols of written speech. ...The crucial… - Gerald James Whitrow

Space-time is curved in the neighborhood of material masses, but it is not clear whether the presence of matter causes the curvature of space-time or whether this curvature is itself responsible for the existence of matter.

Our idea of the universe as a whole remains a product of the imagination.

From a careful determination of the amount of solar heat that which would fall per minute on an area of one square centimetre placed perpendicular to the radiation as it falls on Earth's surface and from a knowledge of the Earth's distance, we deduce that each square centimetre of the solar surface radiates on the average of about the rate of a nine horse-power engine.