Schroeder's works frequently cite Talmudic, Midrashic and medieval commentaries on the biblical creation account, such as commentaries written by the Jewish philosopher Nachmanides. Among other things, Schroeder attempts to reconcile a six-day creation as described in Genesis with the scientific evidence that the world is billions of years old, using the idea that the perceived flow of time for a given event in an expanding universe varies with the observer's perspective of that event. He attempts to reconcile the two perspectives numerically, calculating the effect of the stretching of space-time, based on Albert Einstein 's general relativity.