My partial opinion, for what it's worth: I believe that the universe that God created was originally perfect. However, when the fall of man came, so too came a decline in the world's perfection (as explained in the second law of thermodynamics). Things are deteriorating at an exponential (rather than a linear) rate, and consequently, I think time itself may be slowing down. In essence, I think God very well may have created the universe in seven literal days and that the earth may only be a little over 6000 years old.

With that said, there are volumes of information written on this topic, of which it would take my feeble mind several lifetimes to read and still not fully comprehend. For anyone with a true interest in the topic, read/study/pray, etc. and arrive at your own conclusions. Just my opinion.