Reference: The Nature of the Physical World
This paper presents Chapter III (section 4) from the book THE NATURE OF THE PHYSICAL WORLD by A. S. EDDINGTON. The contents of this book are based on the lectures that Eddington delivered at the University of Edinburgh in January to March 1927.
The paragraphs of original material are accompanied by brief comments in color, based on the present understanding. Feedback on these comments is appreciated.
The heading below links to the original materials.
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The Absolute Distinction of Space and Time
By dividing the world into Absolute Past and Future on the one hand and Absolute Elsewhere on the other hand, our hour-glasses have restored a fundamental differentiation between time and space. It is not a distinction between time and space as they appear in a space-time frame, but a distinction between temporal and spatial relations. Events can stand to us in a temporal relation (absolutely past or future) or a spatial relation (absolutely elsewhere), but not in both. The temporal relations radiate into the past and future cones and the spatial relations into the neutral wedge; they are kept absolutely separated by the Seen-Now lines which we have identified with the grain of absolute structure in the world. We have recovered the distinction which the Astronomer Royal confused when he associated time with the merely artificial Now lines.
Past, future and distances in all directions, exist only for a localized subjective viewpoint. They do not exist for a universally objective viewpoint, for which it is a landscape that can be eyed all at once.
Space and time are aspects of a substance that reflect how substantial the substance is. A table has certain fixed spatial dimensions. That is the space of the table. The space of the table is not its background. The table endures for a certain time in a useful condition. That is the time of the table. The time of the table is not its background. The background provides a reference point to measure space and time of the objects made of that substance.
Knowing the appropriate universal laws all space and time may be surveyed at once.
I would direct your attention to an important difference in our apprehension of time-extension and space-extension. As already explained our course through the world is into the absolute future, i.e. along a sequence of time-relations. We can never have a similar experience of a sequence of space-relations because that would involve travelling with velocity greater than light. Thus we have immediate experience of the time-relation but not of the space-relation. Our knowledge of space-relations is indirect, like nearly all our knowledge of the external world—a matter of inference and interpretation of the impressions which reach us through our sense-organs. We have similar indirect knowledge of the time-relations existing between the events in the world outside us; but in addition we have direct experience of the time-relations that we ourselves are traversing— a knowledge of time not coming through external sense-organs, but taking a short cut into our consciousness. When I close my eyes and retreat into my inner mind, I feel myself enduring, I do not feel myself extensive. It is this feeling of time as affecting ourselves and not merely as existing in the relations of external events which is so peculiarly characteristic of it; space on the other hand is always appreciated as something external.
“Future” is made up of projections derived from present and past data. It is as absolute as the knowledge of data and the laws of projection. The data provides the space-relations. The laws of projection provide the time-relations. Our physical sense-organs are greatly enhanced by the mental sense-organ that can determine universal laws and project data based on them.
That is why time seems to us so much more mysterious than space. We know nothing about the intrinsic nature of space, and so it is quite easy to conceive it satisfactorily. We have intimate acquaintance with the nature of time and so it baffles our comprehension. It is the same paradox which makes us believe we understand the nature of an ordinary table whereas the nature of human personality is altogether mysterious. We never have that intimate contact with space and tables which would make us realise how mysterious they are; we have direct knowledge of time and of the human spirit which makes us reject as inadequate that merely symbolic conception of the world which is so often mistaken for an insight into its nature.
The structure of a table is very simple compared to the structure of human personality. The structure of table involves a few simple laws. The human personality involves a large number of laws that account for many more dynamic variables. Any mystery comes from complexity of the situation not yet resolved.
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