Heisenberg also appears to accept the view that the universe had a beginning. But at the same time, he is doubtful about the validity of such a view. He observes: “With respect to time, there seems to be something like a beginning. Many observations point to an origin of the universe about four billion years ago; at least they seem to show that at that time all matter of the universe was concentrated in a much smaller space than it is now and has expanded over since from this small space with different velocities. The same time of four billion years is found in many different observations. (e.g. from the age of meteorites, of minerals on the earth, etc.), and therefore it would be difficult to find an interpretation essentially different from this idea of an origin. If it is the correct one, it would mean that beyond this time the concept of time would undergo essential changes. In the present state of astronomical observations, the questions about the space-time geometry on a large scale cannot yet be answered with any degree of certainty, but it is extremely interesting to see that these questions may possibly be answered eventually on a solid empirical basis. For the time being even the theory of general relativity rests on a very narrow experimental foundation and must be considered as much less certain than the so-called theory of special relativity expressed by the Lorentz transformation.[1]
Footnotes