3 billion
The first viruses originate (at the latest)
2.9 billion
The Pongola glaciation strikes Earth
2.8 billion
The Vaalbara super-continent forms
2.7 billion
The Kenorland super-continent forms
2.5 billion
The Proterozoic era begins
A modern atomic clock loses just one second in 300 million years. If it had begun to tick at the beginning of time 13.8 billion years ago, it would be less than one minute out today. That remarkable accuracy is more than enough to coordinate our daily calendars. But physicists are always searching for something more.
Their problem is that the clocks have hit the limits set by the inaccuracies of atoms themselves. Atoms are controlled by the odd laws of quantum mechanics, which dictate that atomic oscillation can never be known entirely accurately. But now scientists have found a way to make atomic clocks still more accurate by employing another odd quantum mechanics phenomenon – the
