Many key events in the history of humankind show evidence of having been intended by human beings from the future, who took specific actions that would steer the world in a particular direction. Time travellers – some of them anonymous, some celebrated in history – have made alterations to our planetary and global environment (the creation of the Moon, the extinction of the dinosaurs) that were necessary to allow us to exist and to develop as an intelligent species. They have also left us markers that show what steps we need to take to progress further. All these interventions were placed retroactively within the ‘timeline’ for future generations, not for those immediately affected.

Key interventions include:

• The creation of the Moon  If the Moon did not exist, nor would we. The author demonstrates that the Moon was built to make it possible for the Earth to become an incubator of life.
• The megalithic yard  Neolithic peoples created a sophisticated, fully integrated system of measurements based on the actual size and mass of the Earth – a ‘marker’ for future scientific developments, surfacing again, apparently out of the blue, in 18th-century Washington, DC.

But the most spectacular revelation lies in our future. By looking at the mathematics underlying many of the inventions, we discover, with unexpected precision, when our first contact with our future selves will happen. This will occur within the lifetime of most readers of this extraordinary book.