Today’s post is a back-to-school special. It’s for the lifelong learners among us. It’s for the lifelong fretters among us. It’s for the metalheads and the ladies with silver hair and the fake blondes (me) – for anyone who ever thinks about the passage of time. Guest writer Matt Osborne takes us on a genial and informative guided tour of Carlo Rovelli’s new book, The Order of Time.
I like to blow my own mind.
To paraphrase Michael Pollan, I think it is healthy for me to “shake the snow globe.”
Left to its own devices, my mind often gets caught in loops of excessive, anxious rumination. So, it is good occasionally to set off what a co-worker of mine calls a “mind grenade.”
Carlo Rovelli’s The Order of Time is one such grenade.
Rovelli, an Italian physicist, lays out an argument that what we conventionally think of as “time” has no basis in the reality of the universe. In other words, there is no time as we commonly conceive of it.
Interested in pulling the pin on this grenade? Set out below is Rovelli’s argument, which (at the risk of draining it of its poetry) I have set out in an outline form in an attempt to get my head around it.
Read as much as you want – just the headings and subheadings, or dig in to the entire explication.
If you get bored, no sweat – you can blow your mind some other way. Listening to Frank Zappa’s “G-Spot Tornado” always works for me: https://www.youtube.com/watch?v=XvpdiIaZZLg
- There is a conventional notion of time that most everyone holds.
Rovelli begins by observing that we conventionally think of time as something that “flows uniformly and equally throughout the universe, in the course of which all things happen.” In this conventional view, there is “a present, a ‘now’ that constitutes reality,” and “the events of the universe succeed each other in an orderly way: pasts, presents, futures. The past is fixed, the future open.”
- This conventional notion of time is wrong.
These conventionally understood characteristics of time have, according to Rovelli, “proved to be approximations, mistakes determined by our perspective, just like the flatness of the Earth or the revolving of the sun.”
When we examine it more closely, our world is, in actuality, “a world without time.” Time does not pass uniformly, there is no differentiated past and future, there is no universal “now,” there is no continuous temporal flow, and the universe does not operate on an orderly timeline.
Here is how Rovelli explains each of these points:
- Time does not pass uniformly.
— Time passes differently depending on elevation. Through the use of high precision clocks, one is able to demonstrate that time passes at different rates at different altitudes. Specifically, the closer one is to the Earth, the slower time passes because “a mass slows down time around itself,” and the Earth is a significant mass. Time passes more slowly in New Orleans than on Driskill Mountain, even though they are geographic points in the same state and same time zone. So, what can we way the true time is? We cannot – we can say only what the times in New Orleans and Driskill Mountain are “relative to each other.”
— Time passes differently depending on speed. Speed slows down time. If two people are together, and then one remains on the ground while another flies in an airplane, time will pass more slowly for the person in the airplane. When measured using precision watches, a watch on board the airplane will display a time that lags behind the time displayed by a watch that remains stationary on the ground.
- There is no difference between past and future.
With one exception (that heat passes from hot bodies to cold), the basic laws of physics do not distinguish past and future. So, “in the elementary laws that describe the mechanisms of the world,” there is no difference between past and future.
- There is no “now.”
There is no “now” that everyone shares.
Let’s say that your sister and you are speaking with each other across the room, and you smile at one another. Even though you are in the same room, there is a delay before the light from her reaches you, and before the light from you reaches her. So, when you see her smile in your “now,” you are seeing something that she previously did in her past. And when she sees your smile in her “now,” it will be something you did in your past.
With someone who is in the same room, this light travel delay may be only a few nanoseconds, but at greater distances (say, between the Earth and a distant star) the delay is more pronounced. So, when we look at a distant star in our “now” on Earth, we are seeing the star’s far past (and if some being on that star were able to view us in that being’s “now,” it would be our far past that the alien would be seeing). So, there are no simultaneously experienced moments in the universe, there is no shared “now.”
- Time is not continuous.
“A minimum scale exists for all phenomena,” including what we conventionally think of as time.
At the quantum level of the universe, there are separate minute (as in the adjective meaning “very small”) events. This means that time consists not of an unbroken line, but rather of separate events, each having a minimum duration. Time, like the rest of the universe, is “sketched in dots,” in a manner that Rovelli likens to the paintings of Georges Seurat.
So, while we may perceive a continuous flow of time at our macroscopic level of perception, the reality is instead a granularity that involves “elementary temporal leaps” from point to point.
- The world does not operate on an orderly timeline.
— “[T]he world is a network of events” (Rovelli’s emphasis) that “undergoes continual transformation.” Even what we perceive as a static “thing” is, in reality, just a lengthy event. Take, for example, a stone. It is not a static thing; rather, it is “a complex vibration of quantum fields, a momentary interaction of forces, a process that for a brief moment manages to keep its shape, to hold itself in equilibrium before disintegrating again into dust, a brief chapter in the history of interactions between the elements of the planet.” So, each “thing” we see, be it a stone, a storm, or a human being, is a temporary “collection of occurrences” subject to change. (Buddhist readers will recognize here the notions of impermanence and interbeing.) The world is “not ordered along a time line [sic], is not measured by a gigantic ticktocking.” Rather, the world is “a boundless and disorderly network of quantum events.”
— As noted earlier, “now” is relative. There is no “objective global present.” Accordingly, the universe is not arranged pursuant to “a single orderly sequence of times.”
- If our conventional notion of time is wrong, then why do we sense it so strongly?
Having dispensed with the features of time that we thought reflected the reality of the universe, Rovelli wrestles with why it is that we perceive and cling to these conventional notions of time with such force: “In a world without time, there must still be something that gives rise to the time that we are accustomed to, with its order, with its past that is different from the future, with its smooth flowing.”
Rovelli’s conclusion is that the time that we perceive arises from our approximations of the universe, which are based on our limited perspective. So, for Rovelli, “time is ultimately… more about ourselves than about the cosmos.”
He explains this as follows:
- Time arises from our macroscopic perspective, which results in a “blurring” of reality.
“[W]e are ignorant of the microscopic details of the world,” Rovelli observes. As humans, “[w]e cut the world into large slices… that are meaningful for us.”
For example, when we view a glass of warm water, we do not see the agitated molecules within it. We “blur” these minute details. As a result, “[w]e see the water in a glass like the astronauts saw the Earth from the moon: calm, gleaming, blue.”
Recalling his discussion of the effect of altitude, mass, and speed, Rovelli explains that “[i]n our everyday life we move at low speeds in relation to the speed of light and so we do not perceive the discrepancies between the different proper times of different clocks, and the differences in speed at which time passes at different distances from a mass are too small for us to distinguish.” So, we go with what we perceive – the macroscopic, blurred view.
- The sense of the flow of time occurs from our mistaken perception of entropy.
Rovelli believes that we perceive of a flowing from past to future because of the way in which we perceive entropy.
Entropy is a measure of disorder. Low entropy is low disorder. High entropy is high disorder. We perceive the past as fixed (ordered, low entropy), and the future as uncertain (disordered, high entropy). But, again, we have this perception because of our macroscopic vantage point, which blurs our view so that we do not see the disorder that actually was present at the particular point in the past.
Consider, for example, a deck of cards (which is Rovelli’s choice for illustrating the point). We separate the black cards from the red cards, and take that ordering as our starting point. If we then shuffle the cards, red has mixed with black, and so we see a change from the past, ordered point (red separate from black), to the new, disordered point (red mixed with black). But this perception is because of the blurred order that we originally imposed — i.e., the particular macroscopic view (red vs. black) that we chose. If we had looked more closely with a different perspective, we would have seen that even when the cards were separated red from black, the numbers and suits were jumbled. Had we looked from that perspective (numbers and suits) rather than the perspective we chose (color), we would have seen disorder. So, when we “observe the microscopic [my emphasis] state of things, then the difference between past and future vanishes.”
For Rovelli, then, the difference between past and future is another function of our “blurred vision.” We perceive a change from low entropy (past) to high entropy (future) because of “the number of microscopic states that our blurred vision of the world fails to distinguish.” We interact only with a “subset of the world’s variables” and “are attuned to a very particular subset of aspects of the universe.”
At bottom, then, “the flow of time is not a characteristic of the universe.” Rather, “it is due to the particular perspective that we have from our corner of it.”
- Time also is a product of the way our brains work.
“[T]he brain is a mechanism for collecting memories of the past in order to use them continually to predict the future.” For example, “[i]f someone throws something at us to catch, our hand moves skillfully to the place where the object will be in a few instants: the brain, using past impressions, has very rapidly calculated the future position of the object that is flying toward us.”
This ability to anticipate future events based on past experiences “obviously improves our chances of survival and, consequently, evolution has selected the neural structures that allow it.” Accordingly, human consciousness “is based on memory and on anticipation.”
This structure of consciousness — traces of the past stored in memory combined with the “continuous process of anticipation” — is “the source of our sensing time as time.”
What then, is Rovelli’s final word on time? If ours is a world without time, if time has no reality in the universe, what is time?
“Time,” concludes Rovelli, is “the form in which we beings… interact with the world.” Time is not the time of the universe; rather, “time is the time of mankind.” Time is “the time of our experience.”
So, what to make of Rovelli’s slim, at times poetic, and often daring volume?
I don’t doubt his argument in the least. Time does seem to pass more slowly in New Orleans. Those of us in the southern United States have long known that, for both good and ill, there often is little or no difference between past, present, and future. And those of us who have had teenaged children certainly know that there is no universally shared “now” (“I need a new sports bra.” “When?” “Now.” “Well, it’s 10:15 PM, nothing is open.” “But I have a game tomorrow.”).
I also understand Rovelli’s conclusion that the dimension of time is a personal dimension. Since the death of my father nearly one year ago, time has become for me a measure of existence and value. I am even more acutely aware that my time in this form (my body being one of Rovelli’s temporary “collection of occurrences”) is limited. Unless I have Olivia de Havilland’s genes, my life on this planet is at least half over. Already when I get out of the car, I look like the three stages of man as I struggle to get upright. I don’t want the remaining time wasted with nonsense and half measures – as the Clutch song says, “If you’re gonna do it, do it live on stage, or don’t do it at all!”
I want my time to be a time filled with Kurosawa films, Philip Marlowe stories, Derek Trucks guitar solos, Motorhead riffs, Drew Brees completions, cajun food, lying brain to brain on the floor with my dog (you can inhabit the same dream with your dog that way, you know), texting with my college daughters at midnight, and holding my wife’s hand when I wake up at 3:30 AM and can’t go back to sleep.
That, to paraphrase Raymond Chandler, is the kind of time they don’t make in watches.
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