Western monotheism is more concerned with the abrupt and final breakthrough of God into human life. Many Christians differ on the details surrounding the idea of Christ's Second Coming--no surprise, given how vast and varied the world's Christian population is. But if there is a shared belief, it is that from that event onward, we're to operate quite clearly on God's time, not ours.

Belief in the Earth's end and a divine reckoning with humanity don't necessarily cancel each other out. As others have pointed out, science and religion aren't always at war, despite what the most dogmatic atheists and fundamentalists claim.

Beyond astrophysics and theology, it's not possible to leave the subject without giving a nod to human nature itself as a possible agent of annihilation. To have grown up since 1945 means living in the shadow of potential horror. But literature tells us that the idea of people managing to destroy their species and their home has long troubled the imagination.

More than a century ago, H.G. Wells wrote about an unnamed Time Traveler who ventures so far into the future that he encounters a still-extant world populated by only the crudest forms of life. Seated on his machine on a beach roamed by enormous crabs, he reflects on "the sense of abominable desolation that hung over the world."

Wells wrote his novel before World War I, which rendered the possibilities for human self-destruction more acutely. Shortly after that event, Robert Frost described the stakes in "Fire and Ice." He sided with those who wanted human time to end in love. "But if it had to perish twice," he wrote about Earth, he had come to "know enough of hate/ to know that for destruction ice/ is also great/ and will suffice."