It has been demonstrated both mathematically and experimentally that time is not a constant, but is dependent on the gravitational pull at the location where time is being measured. This concept was first proposed by Albert Einstein and is called gravitational time dilation.
Numerous experiments seem to indicate that this strange concept is true. For instance, time moves 5 microseconds per year slower at the Royal Greenwich Observatory (which is located at sea level) than it does at the National Bureau of Standards in Boulder, Colorado (which is 1 mile above sea level). Atomic clocks flown around the world in different directions seem to vary by the amount predicted by Einstein’s equations. The direct result of this gravitational time dilation is that seemingly strange things happen to time near areas of space known as black holes.
A black hole is an area where matter is so concentrated that its gravity prevents even light from escaping. Indirect observations seem to indicate that several areas of our universe do indeed contain black holes. Black holes are so dense that they actually "bend" the fabric of space. In addition, time moves exceedingly slow at the boundary of the black hole. Thus, if you could move from the center of a black hole outward, while observing what was happening far away, it would appear that clocks and all natural processes were proceeding in rapid fast-forward. Although one has never been observed, Einstein’s equations also predict the existence of "white holes". Instead of collapsing inward, matter (and space itself) would expand outward from a "white hole". When matter inside the white hole moves past the boundary, the boundary begins to shrink inward. Eventually the radius shrinks to zero and the white hole disappears, leaving behind all of the matter which it originally contained. However, the first material out would have aged millions or billions of years while the last material out may only have aged a matter of days.
Dr. Russell Humphreys has proposed that this expansion of a "white hole" rather than the standard "big bang" theory is the method God used to create the universe we live in. Three effects should be apparent if this is how our universe formed. First, the expansion of space would have left a very uniform background radiation throughout the universe. Second, as space itself expanded, the light coming from stars (which formed as the matter moved out of the white hole) would be shifted toward the red end of the spectrum. Third, if the earth was close to the center of our universe, it would have been one of the last things to have emerged from the white hole. Billions of years would have elapsed for distant stars giving plenty of time for light from those stars to have reached the earth. These three observations are exactly what we find as we observe our universe!
From the moment that all the matter of the universe was created (day one of creation), until the earth emerged from near the center of the white hole (at which point stars would have appeared), it is quite mathematically feasible that only four 24-hour-days had passed on earth. Although this theory is quite controversial (and rejected out of hand by those who are committed to evolutionary development theories), this type of work demonstrates that there is not necessarily a contradiction between a six day creation and modern science.