1941: Despite Asimov's anti-religious assertions in "Nightfall," American culture is steeped in religion, mostly Christian, and atheists are looked upon with suspicion.

Today: Society is secularized with prayer removed from public events and schools.

1941: Despite the probable presence of cults since the beginning of religions, cults are generally rare and secret, so the idea of a cult is a strange one used by Asimov in "Nightfall" to represent the worst effects of religion.

Today: The creation and profusion of cults is a well-recognized facet of modern culture that has gained notoriety with the Jim Jones group suicide and the Branch Davidian catastrophe in Waco, Texas.

1941: Knowledge in the field of astronomy seemingly does not extend much beyond that of Asimov's imaginary world in "Nightfall." However, in the real world, it is known that there are other suns beyond the solar system, rocketry is in its...