Strangely enough, the linking of computers has taken place democratically, even anarchically. Its rules and habits are emerging in the open light, rather shall behind the closed doors of security agencies or corporate operations centers.

Despite the metadata attached to each tweet, and despite trails of retweets and 'favorite' tweets, the Twitter corpus lacks the latticework of hyperlinks that makes Google's algorithms so potent. Twitter's famous hashtags - #sandyhook or #fiscalcliff or #girls - are the crudest sort of signposts, not much help for smart searching.

The Fifties and Sixties were years of unreal optimism about weather forecasting. Newspapers and magazines were filled with hope for weather science, not just for prediction but for modification and control. Two technologies were maturing together: the digital computer and the space satellite.

For the modern physicist, reality is the whole thing, past and future joined in a single history. The sensation of now is just that, a sensation, and different for everyone. Instead of one master clock, we have clocks in multitudes.

Every time a new technology comes along, we feel we're about to break through to a place where we will not be able to recover. The advent of broadcast radio confused people. It delighted people, of course, but it also changed the world.

As a technology, the book is like a hammer. That is to say, it is perfect: a tool ideally suited to its task. Hammers can be tweaked and varied but will never go obsolete. Even when builders pound nails by the thousand with pneumatic nail guns, every household needs a hammer.

Information is not knowledge, and knowledge is not wisdom. Reading - even browsing - an old book can yield sustenance denied by a database search. Patience is a virtue, gluttony a sin.

Scientifically, information is a choice - a yes-or-no choice. In a broader sense, information is everything that informs our world - writing, painting, music, money.

We have a habit of turning to scientists when we want factual answers and artists when we want entertainment, but where are the facts about the nature of the self? Neurologists peering at PET scans and fMRIs know they aren't seeing the soul in there.