Indeed, as the above calculation indicates, to take full advantage of the memory space available, the ultimate laptop must turn all its matter into energy.

We couldn't build quantum computers unless the universe were quantum and computing. We can build such machines because the universe is storing and processing information in the quantum realm. When we build quantum computers, we're hijacking that underlying computation in order to make it do things we want: little and/or/not calculations. We're hacking into the universe.

Science has an uncomfortable way of pushing human beings from center stage. In our prescientific stories, humans began as the focal point of Nature, living on an Earth that was the center of the universe. As the origins of the Earth and of mankind were investigated more carefully, it became clear that Nature had other interests beyond people, and the Earth was less central than previously hoped. Humankind was just one branch of the great family of life, and the Earth is a smallish planet orbiting an unexceptional sun quite far out on one arm of a run-of-the-mill spiral galaxy.

When you zap things with light to build quantum computers, you're hacking existing systems. You're hijacking the computation that's already happening in the universe, just like a hacker takes over someone else's computer.

Bits of ignorance are like viruses that are copied and spread by interaction.

According to the standard model billions of years ago some little quantum fluctuation, perhaps a slightly lower density of matter, maybe right where we're sitting right now, caused our galaxy to start collapsing around here.

For hundreds of millions of years, Sex was the most efficient method for propagating information of dubious provenance: the origins of all those snippets of junk DNA are lost in the sands of reproductive history. Move aside, Sex: the world-wide Web has usurped your role.