< See chapter 1 | Continue to chapter 3 > | See all chaptersAristotle and Isaac Newton put forward the key scientific concepts underlying the structure of space and time. They had dominated science before Albert Einstein created his Special Theory of Relativity (STR).
Aristotle considered time to be a measure of change. If nothing changes, there is no time. This idea was supported by Maimonides, Leibniz and Descartes. Hence the question: if time is a measure of change, then of what and for whom? Quite insightfully, Aristotle analyzed a hypothetical situation in which we are in total darkness and experience no impact of any kind on our body. That is, we detect no external changes. Nevertheless, he believed that some kind of movement would occur within our soul, and that it would appear to us that time flowed along with that movement. We feel the so-called 'internal' time. Isaac Newton suggested the existence of absolute time — the ‘true time’ that flows evenly and is not related to anything external. Newton laid out this idea in his fundamental work Mathematical Principles of Natural Philosophy.
Scientific concepts of space can also be divided into two domains:
1) Relationalism — based on Aristotle's idea that space cannot exist independently of its contents (matter, energy).
2) Substantivalism — based on the idea of Newton, who, as in the case with time, postulated the existence of absolute space that exists independently of its content.
Albert Einstein’s Special and General Theories of Relativity radically changed the way science treated space and time. The Special Theory of Relativity is based on Galileo's principle of relativity and on the fact that the speed of light is independent of the speed of an observer in an inertial frame. Einstein's revolutionary insight was to unite space and time in a single whole – absolute spacetime, which is described by the geometry of Minkowski. One of the direct consequences of the Special Theory of Relativity was the elimination of 'absolute simultaneity' as a concept. We will get back to this matter a later.
Einstein's General Theory of Relativity was based on the principles of equivalence between gravitational and inertial mass, and general covariance. Simply put, we can explain general covariance as the independence of the laws of physics from the smooth transformations of a system of coordinates.
From the above we can conclude that the Theory of Relativity reconciled the views of Aristotle and Newton through absolute spacetime.
However, not all the issues have been resolved.
1) Neither GTR nor STR aimed to explain the origin of spacetime. Nevertheless, it is noteworthy that Isaac Newton believed that absolute space and absolute time were created by G-d.
2) The STR presented spacetime as a continuum. At the same time, according to the theory of quantum gravity, spacetime is discrete. Einstein's Theory of Relativity considered time to be determined by the propagation of light signals and did not touch on the flow of ‘internal’ time. The next chapter will cover this issue in more detail.< See chapter 1 | Continue to chapter 3 > | See all chapters