Gravitational Field

In a debate with Dr. William Lane Craig in March, 2014 theoretical physicist Sean Carroll has said the following in his opening speech:

If you have a universe that obeys the conventional rules of quantum mechanics, has a non-zero energy, and the individual laws of physics are themselves not changing with time, that universe is necessarily eternal. The time parameter in Schrödinger’s equation, telling you how the universe evolves, goes from minus infinity to infinity.1