Why do we remember the past and not the future? What does it mean for time to “flow”? Do we exist in time or does time exist in us? In lyric, accessible prose, Carlo Rovelli, bestselling author of Seven Brief Lessons on Physics, invites us to consider questions about the nature of time that continue to puzzle physicists and philosophers alike.
If you live on a mountain, you experience more time than people who live at sea level, but you also appear to grow older faster than they do. Would you rather live on a mountain, at sea level, or does it matter?
Likewise, people staying still experience more time than people traveling fast. How do you think this relates to astronauts traveling in fast rockets? What about an astronaut’s proximity to the Earth’s gravitational pull? How do these two things affect the way they experience time?
Aristotle said that if nothing changes or moves, time ceases to pass. Newton said there is a “true” time that passes no matter what. What are your thoughts on these competing theories and how Einstein synthesized them with the idea of curved spacetime?
Rovelli says that there is nothing that we can reasonable call the “present.” Why does he say this and do you agree? In what contexts might the present exist?
Rovelli does not believe in the theory of the Block Universe or “eternalism.” The idea has come up in recent popular media such as with Alan Moore or the film Arrival. What do you like and dislike about the theory? Do you think it is at all possible?
The difference between past and future may be that entropy was low in the past. In Rovelli’s chapter on perspective, could it be that we only think that entropy was low in the past because of our perspective? Are these two ideas mutually exclusive or can they work together? How does this relate to thermal time?
Bertrand Russell said that “the law of causality … is the relic of a bygone age.” If there’s no such thing as causality, why is it we perceive cause and effect?
What do you think about Rovelli’s opinion about death, that our fear of death is an error of evolution caused by an exaggerated ability to predict the future?
Book Club Goodies
Best drink to serve: The red wine Zenato ‘Alanera’ Rosso Veronese is from Rovelli’s hometown of Verona, Italy. Or espresso, the most Italian of all beverages!
Best snack to make: Parmesan Thyme Bread Crust Snacks
About the Author
Carlo Rovelli is an Italian theoretical physicist, the head of the Quantum Gravity group at the Centre de Physique Théorique of Aix-Marseille University and one of the founders of the loop quantum gravity theory. His previous books include Seven Brief Lessons on Physics—an international bestseller translated into more than forty languages—and Reality Is Not What It Seems.