The Last Syllable of Recorded Time

What time is it? Most of us ask this question unthinkingly, several times a day. Time to eat. Time to sleep. Time to work, to watch the news, and so on. But we are reminded recurrently—as on New Year’s Eve, for example—that clock time differs depending on where you live on the planet. Revelers in Australia are already celebrating the New Year while we in America still have hours to go before the Times Square ball drops (and if you’re in California, the ball has already dropped at nine o’clock, but our TV channels kindly re-run the tape for us at midnight Pacific Time.) So even the dullest of us knows that time is different—but regularlydifferent—in different time zones; and that the “now” I am experiencing at this moment is the same as everyone’s “now” no matter what the clock says in different parts of the globe. 

            Now comes Carlo Rovelli, a physicist whose specialty is ‘loop quantum gravity,’ to disabuse us of even this simple notion. Time is not at all simple, Rovelli tells us in his new book The Order of Time, (Penguin: 2018), and in fact may not even exist. And there is no “now” that prevails throughout the universe. At one point he even says it plainly: “The time of physics is, ultimately, the expression of our ignorance of the world. Time is ignorance” (140). 

            To summarize what Rovelli means is not easy, and I’m not sure I understand many of his arguments, beautifully phrased as they are. But here is what I can more or less comprehend. First, he gives us a brief lesson in the history of speculations about time. Aristotle was the first to ask himself ‘what is time?’ and he concluded that “time is the measurement of change.” Pretty good. We can all see the logic in that. But Newton disagreed, and reached the opposite conclusion. Regardless of objects and the changes in them and in our world, there is something called “true time,” said Newton. This is the time, perceived and measured by physicists with their instruments, that goes steadily on regardless of whether things are changing or not. All of Newton’s principles and theories (and our clocks) depend on this notion of time. But, of course, along came Einstein, and he upset Newton’s sensible notions once again when he introduced his notion of space and time as “fields.” As “fields,” space and time become space/time, “the fabric on which the rest of the world is drawn” (74) as Rovelli puts it. And what this means for time is that it is no longer independent, as Newton thought, but relativeand thus, together with space, interacting with the rest of the world. We all know of the example of a twin in space aging more slowly than his sibling on earth because of the differing speeds at which they travel. But very large objects also have a noticeable effect on this fabric of spacetime, which is why clocks run more slowly near large objects: their gravitational fields distort the very fabric of time. Rovelli points out, in this regard, that clocks (very accurate ones) even show time passing more rapidly high on mountaintops than at sea level, due to this effect.  

            Rovelli then takes us into the strange world he studies, quantum mechanics, and tells us how it has, in turn, essentially demolished even the relativity of time Einstein discovered. In quantum mechanics, things get very strange indeed, and, according to Rovelli, so does time. The scale, of course, is beyond our imagining: it is called the Planck scale. For grains of time, Rovelli gives us the figure of 10^-44 seconds, or “a hundred millionth of a trillionth of a trillionth of a trillionth of a second” (82). With such infinitesimal units, Rovelli speculates that “the notion of time is no longer valid” and “values of time t do not exist.” Thus, time at this level is not a continuous flow, and our notion of time loses its meaning. When added to the indeterminacy of everything at quantum levels (physicists call this “superposition”), spacetime gets so vague as to be cloudy, fluctuating. And here “even the distinction between present, past, and future becomes fluctuating, indeterminate,” just as with elementary particles. This means, according to Rovelli, that “an event may be both before and after another one” (88). If this doesn’t boggle your mind, you haven’t read that correctly. 

            What I like most about Rovelli is his writing ability and his sense of humor. Consider this little zinger, for example, where he is trying to emphasize his point that the ‘physical substratum’ that determines duration “is a quantum entity that does not have determined values until it interacts with something else” and then onlyfor that specific interaction; “they remain indeterminate for the rest of the universe” (90). It’s like many ‘things’ in the quantum universe: they do not take form as substances until they interact with an observer, until we look at them. In fact, they are better understood as “events” rather than “things.” And these “events” happen in what appears to be not the orderly, past-to-present fashion theorized by Newton or even Einstein, but in a kind of random order that is at best local. Hard to understand, but here is Rovelli’s metaphor to make this more humanly relevant: 

The events of the world do not form an orderly queue, like the English. They crowd around chaotically, like Italians (96). 

You gotta love a physicist, Italian himself, who writes like that. 

            One of Rovelli’s main ideas concerns what he calls “blurring:” this refers to the fact that we cannot see deep into matter, into what is going on at the quantum level, so our vision of the world is ‘blurred.’ Rovelli writes it this way: “the quantum indeterminacy of things produces a blurring,” even when we think we can measure everything. He goes on, 

Both the sources of blurring—quantum indeterminacy, and the fact that physical systems are composed of zillions of molecules—are at the heart of time. Temporality is profoundly linked to blurring. The blurring is due to the fact that we are ignorant of the microscopic details of the world (140).

So while we “see” a universe which “began” with the Big Bang and its low entropy state (which in turn produces our sense that greater order [low entropy] leads to greater disorder [higher entropy], to past preceding present preceding future—hence our sense of the ineluctable order of time), Rovelli maintains that all of this may be “more down to us than to the universe itself.” In other words, the universe in time appears as it does because of who we are, not how the world is. Here is how he concludes this line of thought:

The low initial entropy of the universe might be due to the particular way in which we—the physical system that we are part of—interact with it. We are attuned to a very particular subset of aspects of the universe, and it is thisthat is oriented to time (147). 

This is significant because everything that we know of proceeds from the growth of entropy; from, that is, sources of low entropy like our sun which is constantly breaking down due to its nuclear burning, but whose breaking down, or entropy, gives us the light on which we and all organisms depend. And of course, the low entropy of the sun comes from “an entropic configuration that was even lower: the primordial cloud from which the solar system was formed” (160), and that low entropy comes from other sources back to the low initial entropy of the universe at the Big Bang. This is the “great story of the cosmos” says Rovelli, the story of time powered by the growth of entropy. And it is the particular story which we, as humans, have become sensitive to, and aware of. A great story, no doubt about it, a story of causality, memory, the history of the happenings of the world, in short, the world in time, but a very limited story, only one story out of many. In short, Rovelli says, our sense of time is peculiar to us and necessarily ignores the vast, timeless goings-on at microscopic levels of which we are mostly unaware. Citing St. Augustine, Rovelli summarizes it thus: “this is what time is: it is entirely in the present, in our minds, as memory and as anticipation” (182). 

            There is more in this fascinating and often beautiful book, but to do it justice requires a leisurely reading, and reflection, and probably re-reading. Reading it like this will change your view of time, at least in part, and perhaps make you reflect on how little we truly know about time and its last syllables and what exactly it is that we are recording. 

Lawrence DiStasi