Time in Genesis 1

From Vern Poythress:

How we measure time affects our assessment of the six days of creation in Gen 1. Within the order that God has providentially established, ordinary people usually do not worry about how to measure time, because many rhythms in time, such as the swings of a pendulum or the beat of the human heart or the movement of the sun in the sky are more or less "in time with" each other. But the six days of creation described in Gen 1 are unusual, because some of the rhythms did not exist until a later point in the sequence of days. The cycle of the greater light (the sun) did not exist until the fourth day. The human heart did not exist until the sixth day. The unusual character of the six days poses problems for how we describe the length of the days, and whether we are sure that the rhythms we now experience operated in exactly the same ways before the completion of the created order. This problem of describing length leads to cautions with respect to assessing more than one of the major theories, such as the 24-hour day theory, the mature creation theory, and the analogical theory. It also introduces caution with respect to the presumption in much of mainstream science that the same rhythms investigated today extend indefinitely into the far past. A simple affirmation of six days of creation is simpler and less definite than any of the theories.