Our awareness that time stretches back long before we were born, and will continue to stretch into the future long after we're gone, lies at the heart of our humanity. Without this sense we couldn't learn from the past, and wouldn't plan for the future. But where did we come from, and where are we going in time? Every culture mythologises time and attempts to answer the ultimate questions: was there a beginning? And will there be an end?

• Michio Kaku