Ten years after his death in 1996, science writer Walter Sullivan’s byline occasionally still appears in the New York Times on obituaries of important physicists, as though he were beckoning them to some quantum-mechanical heaven. This is not a case of necromancy—the background material for Times obits is often written in advance and stored. If the dead really did communicate with the living, that would be a scientific event as monumental as the discovery of electromagnetic induction, radioactive decay or the expansion of the universe. Laboratories and observatories all over the world would be fiercely competing to understand a new phenomenon. One can imagine Mr. Sullivan, the ultimate foreign correspondent, eagerly reporting the story from the other side.

One October day in 1947, the director of the local bank in Marksville, La., woke to find that hundreds of fish had fallen from the sky, landing in his backyard. People walking to work that day were struck by falling fish, and an account of the incident by a researcher for the state’s wildlife and fisheries department later found its way into the annals of scientific anomalies — phenomena waiting to be understood.

The daddy longlegs clinging vertically to my bathroom wall is a marvel of airy symmetry, its tiny head perched delicately at the center of eight arching limbs. A moment later, struck by the back of my hand, it lies crumpled on the floor. I’m sorry, but I don’t like spiders in the house.

If nowhere else, the dead live on in our brain cells, not just as memories but as programs--computerlike models compiled over the years capturing how the dearly departed behaved when they were alive. These simulations can be remarkably faithful. In even the craziest dreams the people we know may remain eerily in character, acting as we would expect them to in the real world. Even after the simulation outlasts the simulated, we continue to sense the strong presence of a living being. Sitting beside a gravestone, we might speak and think for a moment that we hear a reply.

Maybe it's because I already knew the story - about the tragic genius who revolutionized mathematics, helped the British crack secret Nazi codes and died after biting into a poisoned apple. Or maybe I was just in the mood for fiction. For some reason, about halfway through David Leavitt's short, readable life of Alan Turing, I put the book aside for a few days and turned instead to his most recent novel, "The Body of Jonah Boyd." It is actually a novel within a novel, ending with a self-referential twist that made me wonder whether Leavitt had been inspired by Turing's dizzying proof about undecidability in mathematics, in which a computer tries to swallow its own tail.

Except for the robes and the fact that each is addressed as "His Holiness," it would be hard to find much in common between Pope Benedict XVI and Tenzin Gyatso, the 14th Dalai Lama. Yet both have recently expressed an unhappiness with evolutionary science that would be a comfort to the Pennsylvania school board now in a court fight over its requirement that the hypothesis of a creator be part of the science curriculum.

It was on the second day at Cambridge that enlightenment dawned in the form of a testy exchange between a zoologist and a paleontologist, Richard Dawkins and Simon Conway Morris. Their bone of contention was one that scholars have been gnawing on since the days of Aquinas: whether an understanding of the universe and its glories requires the hypothesis of a God.