Leading physicist and Italian author Carlo Rovelli, has authored a fascinating book, The Order of Time. It is about the history of our understanding of time. He brings the reader on a historical journey, from Aristotle to Einstein, and beyond into the 21st century where today quantum mechanics is heavily involved. Rovelli also has an interest in philosophy, and in the book he hints at what the emerging ideas about time might mean for human existence.
In an exclusive interview to science journalist Conor Purcell, he dwelt on the main message of the book: the concept that time can no longer be understood as a single notion. Part of the reason for this is that we human beings — because of our size — can only observe macroscopic variables, and not the microphysics of things. So, the observations we make are clearly time oriented, but only because there is heat involved; time orientation is related to heat and statistical mechanics.
Putting it all together, our perception of time is related to this macroscopic perspective, the idea that we can only see a statistical view, rather than the world as it really is. But time itself would disappear at the molecular level, where the past and future become equally determinable — meaning there would be no apparent difference between past and future.
He writes that “rebellion is perhaps among the deepest roots of science: the refusal to accept the present order of things”. He comes from that generation which in the late 1960s and early 1970s was very much rebellious. It was a time of big dreams, with intentions of building a more just world. He elaborates: “I was immersed in that culture. To some extent it was a failed revolution — the world did not go in that direction at all. So, at one time there was a moment in my life when I became disappointed by that, and in that moment I fell in love with science. What attracted me was that in science you can make real change – you can make revolution, in ways that can be even easier than in the “real” world of politics. In fact in science you must make revolution in order to see further than before.”
Later during his university years, while studying general relativity and eventually quantum mechanics, he realised that this stuff is better than drugs — better than LSD.
He found the problem of quantum gravity so fascinating, and “right there and then I knew that I wanted to study it for the rest of my life. I have since done so, and I feel that it is a privilege to be involved in science, doing what I love to do.”
He acknowledges that one of the reasons people buy his books is because he talks of science and of god. He is an atheist, because he knows he does not know, unlike many theists. “Not because I think I know the answers, and that people who believe in god don’t know them. It’s because I know that I don’t know the answers, and I am aware of this ignorance. I don’t think there should be an arrogance in pretending to know everything, and I struggle to understand how people can be so sure they know about God. For some people it comes natural to think there must be something behind it all.”
He adds: “What is very typical of science is that the more we learn the more we don’t know. I don’t think it’s disconcerting. I don’t think anyone knows where the universe came from, and I think we just have to accept that. We must accept to live at least partly in ignorance, but nevertheless remain absolutely curious.”
(The writer is professor of science and religion and author of Death: Live it!)