Time Scale

In the fastest markets a computer can see a price move, decide and send an order of its own in less than a millionth of a second. In 2010 a company reportedly spent three hundred million dollars laying a straighter cable between Chicago and New York, to cut three thousandths of a second from the trip. At this speed there is no human in the loop at all.

A tenth of a second of looking at a stranger's face is enough for people to judge whether they seem trustworthy. Given longer, they rarely change the verdict - they only grow more sure of it. A great deal of what happens at every larger scale starts with judgements this fast.

In conversation, in every language studied, people take turns with a gap of about a fifth of a second. Finding and saying even a single word takes longer than that, so everyone plans a reply while the other person is still talking. Nobody notices the timing until it breaks.

In March 2023 depositors pulled forty-two billion dollars out of Silicon Valley Bank in a single day, much of it coordinated on phones and in group chats. Regulators closed the bank the next morning. A run that once took weeks of queues outside a branch now takes an afternoon.

The week is the one big rhythm of modern life that follows nothing in the sky. It is pure agreement, kept going without a break for at least two thousand years, and it still decides when billions of people work, rest and shop.

In a study that followed people taking up a new daily habit, it took a median of sixty-six days for the behaviour to become automatic - and anywhere from eighteen days to more than eight months. A change meant to last has to survive at least this long before it runs by itself.

Public companies report every three months, and markets react to every report. In a survey of about four hundred financial executives, most said they would give up value in the long run rather than miss a quarter's earnings target. A clock this short quietly steers decisions meant to last for decades.

Most democracies ask their voters every four or five years. It is the clock governments plan to, and it is shorter than nearly every problem they are asked to solve.

A human generation runs about twenty-seven years. Some of the slowest shifts in what a society believes move at this pace, as people who grew up with one set of assumptions give way to people who grew up with another.

Someone who starts work at twenty-five pays into a pension they may still be drawing at ninety. That is a promise that has to hold for sixty-five years - through a dozen or more governments and several recessions.

Across forty-one empires of the ancient world, the typical one lasted a little over two centuries. A young empire was about as likely to fall in any given year as an old one: their endings look less like old age than like radioactive decay.

Of the carbon dioxide released today, between a sixth and two fifths will still be in the air a thousand years from now. That is longer than almost any government or company has ever lasted. Here the clock of the problem runs longer than the clock of anyone deciding about it.

Writing began about five thousand two hundred years ago in the cities of Mesopotamia, and most of the oldest tablets are not stories or laws but accounts: grain, beer, livestock, and who owed what to whom. Writing let a system remember more than any of its people could.

Farming began about twelve thousand years ago. Every large system on this site - cities, states, writing, money - is younger than that. For almost all of human existence before it, people lived in bands small enough for everyone to know everyone.

Our species is about three hundred thousand years old. Farming covers the last four per cent of that time, writing less than two. The systems that now run eight billion lives are, on this scale, very new - and still being tried out.