an angle, we get
so that
all other
’s vanishing. It may be noted that this change in the value of the
’s is due solely to our change of co-ordinate system; it is in no wise attributable to any change in the structure of space-time. This remains flat, as before.
Now we know that in a gravitational field space-time is no longer flat; it becomes curved, and its law of curvature outside matter is given by