why time flies

12rovelli-cover-master180Carlo Rovelli at The New York Times:

Alan Burdick’s “Why Time Flies” certainly does not answer our every question. And precisely for this reason it captures us. Because it opens up a well of fascinating queries and gives us a glimpse of what has become an ever more deepening mystery for humans: the nature of time.

Time may appear unproblematic at first. What is there to say about it? It flies, things happen in the fullness of it, clocks measure it, and we are well aware of its passage. This review shall take you perhaps three minutes to read. Nothing particularly curious about that. But the closer we look, the less clear our temporal sense becomes: First, our brain, body and cells all keep track of time in a variety of ways that are not all that well understood. Psychologists are puzzled by a wealth of experiments showing that we process time in more subtle and complex ways than we expected. Some neuroscientists interpret the brain as a “time machine,” whose core mechanism is to collect past memories in order to predict the future. Philosophers debate the very existence of time. And perhaps most disconcertingly of all, physics teaches us that physical time happens to be astonishingly different from how we intuit it: runs at different speeds, at different altitudes; is distorted by matter; is not organized in a straightforward past, present and future. Advanced tentative theories of the universe even discard temporality altogether from the basic ingredients of the world. From whatever side we address it, the nature of time is a source of perplexity and wonder.

more here.