Our tree-lined street borders a deep woods. In the autumn the supply of dead leaves seems inexhaustible. When yesterday’s litter has been carted off, tomorrow’s wind will inevitably scatter a new swatch of leaves over our lawn. When it rains, some of them will inevitably manage to smear themselves tightly onto our concrete driveway.
Rain fell most of last night, but this morning it tapered off to showers. During a sunny break this afternoon I hauled out the hose to flush the soggy leaves off our driveway. With the nozzle set to concentrate the full force of the water into its most powerful jet, I routed the unwelcome messies strip by strip.
As I worked ever closer to the street, Michael Coventree approached on the sidewalk. He stopped at a safe distance, waved amicably and greeted me with, “G’day, Mr. Clean.”
Grinning wickedly, I marched the forceful splash from the hose closer and closer to Michael’s feet.
I chortled “Ya-a-h!” menacingly. “Now I can pay you back for bopping me with that volleyball!”
Michael raised his eyes imploringly to the sky. “Is there no forgiveness?” Then he held out both arms authoritatively, palms toward me, as if he were King Canute forbidding the water to come an inch farther. Immediately my threatening jet of water drooped to a pitiful dribble.
Before I could ask, “How did you do that?” Michael pointed up the street. At the boulevard corner a public service crew had opened a fire hydrant to flush out the water main. That’s what had reduced the pressure in my hose. We both laughed at the remarkable coincidence of events.
“Where are you heading?” I asked.
“Home,” he said. “I’ve been walking along the shore.”
A very determined, swift current of water had begun to flow down past our driveway. We both moved to the curb and watched the stream carry my debris away down the curbside gutter. Michael quietly recited those famous lines from Isaac Watts’ hymn: “Time, like an ever-rolling stream, bears all its sons away.”
A little snidely, I remarked, “Streams don’t have sons – or daughters! Lots of streams flow without rolling. Anyway time isn’t a fluid substance that can take on the form of a stream.”
“Whoa, boy!” Michael recoiled in mock horror. “Obviously astronomers should not be wandering the streets reciting poetry to literary critics.”
Touching his arm apologetically, I said, “Sorry. I spent a couple of hours this morning critiquing what people say about the passing of time. The theme that time flows like a stream is common enough, but I think it blurs an understanding of the real nature of time.”
Suddenly I had an idea. “Look, are you in a hurry to get home? Have you time for coffee? We could talk.”
“After walking for over an hour,” Michael replied, “I’d be glad to sit down and … influence your literary future.”
Kay heard us come in and welcomed Michael. She knows I respect him highly. As we headed toward the study, she quietly suggested, “Coffee?” I nodded.
Michael settled back in my recliner chair and raised the footrest. “Now,” he said, “tell me what you have against saying that time is like ‘an ever-rolling stream.’”
His head-on approach to a big question put me a little off balance, but I began. “I can certainly understand why the ‘flowing stream’ analogy has always made a certain amount of sense. When water flows past, anybody can see that different water keeps coming along to replace what has just moved on downstream. Random patterns of foam, twigs and leaves come along and pass by. Similarly people find that when present situations go away, new ones immediately take their place. The relations between things keep changing, coming and going with time. This transience gives some credibility to the notion that time flows like a stream.
“Nevertheless,” I continued, “as a model for time the analogy of a flowing stream is not only superficial – it’s downright misleading and not nearly comprehensive enough.”
“How so?” Michael asked.
“It’s hard to find words suitable for describing flowing fluids,” I said. “‘Flowing’ means that from moment to moment different ‘fluid particles’ are passing a given stationary position. Each ‘droplet’ of the fluid is constantly moving with respect to fixed places along the watercourse. But nothing in the universe can be called a ‘fixed place.’ Everything is on the move. There are no stationary bridges or banks for the ‘stream of time’ to flow under or past. Neither are there any observers who are not themselves affected by time-changing.”
Michael objected, “But you don’t have to be absolutely motionless to watch something move past you.”
“Certainly not,” I agreed. “Things do move in the same direction at different rates. A jogger can pass a snail which is crawling at full speed ahead. But cosmic time, I believe, proceeds at the same rate with respect to both the jogger and the snail.
“Motion and cosmic time are simply not the same thing. A motion happens in a definite portion of space, but time happens everywhere at once. Motion implies going from one place to another, but time keeps happening in the same place. Motions can be started and stopped, reversed, accelerated or slowed, but the rate of cosmic time cannot be controlled. A flowing stream speeds up where its banks narrow in and slows down where its banks spread farther apart – and it stops altogether for a while when it comes to a dam. But cosmic time stops for nothing. Out on the driveway I controlled the shape and power of the stream from my hose by opening and closing valves, but no plumbing devices have any effect on time. Streams may dry up, but the supply of time never ceases.”
Just then Kay arrived with a plate of muffins and a carafe of coffee.
When we had thanked her, and were enjoying what she had brought in, Michael returned to the “flowing time” theme. “Okay. Okay. Motion and time are different. Streams and time have different characteristics. But I’m sure you will agree that time does ‘proceed.’ That’s mostly what people are trying to express when they say that time flows, flies, passes or marches on.
“Any child has seen water start to trickle into one end of a dry ditch. As the water advances, the flooded part of the trench gets longer and longer. When children hear adults talk about living longer until ‘time’s ever-rolling stream’ carries them away, they naturally understand that time moves on just like water flows. That notion is reinforced when their teacher is drawing a ‘time-line’ on the board. The line lengthens the way one’s lifetime lengthens. Do you think that a time-line is a better model for time than a flowing stream?”
“History teachers and people who deal with lengthy industrial processes do find it handy to represent the order of certain events or successive periods of time by drawing a length of line and marking it off in sublengths,” I replied. “But if taken strictly, that too can give a false impression. I think a time-line is really poor as a model for time.”
“Tell me,” said Michael.
Picking up a penciled sheet of notes, I grinned. “Okay, better brace yourself!
“First of all, time doesn’t actually happen in a one-dimensional linear form. It keeps changing the configuration of everything on every level throughout the bulk of this whole three-dimensional universe.
“One part of a line looks just the same as any other part. But time is not like that. No two momentary states of the universe are ever exactly the same.
“To give a special, single significance to a certain stretch of an unvarying time-line, it must be specially marked off, labeled and dated. All periods of cosmic time, even the briefest, are quite different from each other, whether or not special names or dates are assigned to them.
“Once an actual event settles into the past, its quality automatically becomes radically different from what it was when it was a vividly present moment. Anybody can tell the difference between what is present and what is no longer present. We can participate in a situation that is actually present, but we’re powerless to change the past. Except perhaps for its length, one segment of a time-line, however, looks just the same as another. The richness of an experienced life-time or period of history bears hardly any resemblance to stripped down, abstract time-models, whether time-line drawings or a series of numerical dates.”
Michael prodded me further. “Yes, but we do sometimes want to know how long it took to complete a certain activity. Or how long it will be until something will happen or stop happening. What do you have to say about measuring the rate at which time … uh … proceeds?”
He paused, then continued. “You will agree that we try to use clocks as time-measuring devices, presuming that time has some kind of movement. If it is legitimate to speak of the speed of a moving object, can we then not speak meaningfully of time’s movement, and perhaps then determine the rate at which time itself goes, flows or ‘flies’?”
I was ready for that question. “To measure the rate at which time itself is going we can’t use the method we use for measuring the speeds of moving objects. Using clock-time to measure the rate at which clock-time passes doesn’t make sense. We know only that a clock’s hour hand is supposed to move twice as fast as the radial rotation of Earth. But we don’t know in any absolute sense how fast Earth actually turns. To measure that we would have to find some ultimate motion other than Earth’s whose standard units for rating motion could be compared with the rate of Earth’s rotation, or any other movement. Then to determine the rate of any such transcendent standard time, we would need to be able to compare it with yet another, even higher level of standard time. Up, up and away the echelons of standard times would mount, with no limit which could be considered ultimate.
“But even the adoption of some ultimate standard motion would not help us to discover the speed of time. We have already agreed that motion and time, though mutually related, are not the same. Time goes on even if nothing is obviously moving. Things keep on existing and aging whether they are moving or not. There’s simply no way to specify the rate at which universal cosmic time ‘goes, flows or flies’.”
Michael was being playfully difficult. He smiled slyly. “Nevertheless you do sometimes talk about a moment’s coming or going. Just how long would you say a ‘moment’ is?”
I smiled right back. “That question simply rephrases the question you just asked me. If I could measure duration in terms of some ultimate standard duration I could offer an answer.
“You’re a physicist. You know the problems involved in measuring a smidgen of time. A ‘long time’ can be specified in standard clock-time units, but I don’t think there is any practical way to isolate and measure an absolutely minimum interval of time. It takes time to register the beginning and the end of a time interval. No instrument can react absolutely instantaneously, so the start and finish of any minimal measured interval would inevitably be slightly smeared. When the time interval of interest gets to be about the same length as the time which elapses during the smear, the shortest possible duration obviously cannot be accurately measured. So no one will ever be able to say exactly how long a moment is.”
Michael agreed. “Measuring time is a lot harder than measuring the rate of flow of a stream of water.”
“Anyway,” I said, “time isn’t a fluid that can be measured easily like water. Nobody ever thinks of dipping up a cupful of time, or filling a jar with it.
“Nevertheless,” I confessed, “I feel that time is actually being measured out, but not by us humans. Time never comes upon us like a sudden and overwhelming tidal wave which sweeps everything along with it. Everything that might happen doesn’t happen all at once. Rather time is being doled out at some steady rate, even though we have no way of measuring that rate.
“In science any process which keeps happening at an invariably regular pace is assumed to be under some kind of control. But I notice that the physical sciences avoid asking what controls the admittedly regular ongoing of time. Time’s regularity is accepted without comment as a ‘given’ rather than as a perfectly controlled regularity.”
“Well,” Michael admitted candidly, “a long time ago scientists gave up speculating about the source of time. We’d rather investigate processes which we think we can measure, understand and perhaps control. We know that we can’t understand or control time, so we take account of it but leave speculating about its nature and origin mostly to philosophers.”
“Streams of water have known sources,” I said. “They come from the precipitation that falls in areas between watersheds. But time arises everywhere at once. There’s no particular source place in the universe from which time arises.”
“Good point,” agreed Michael. “And I suppose we shouldn’t overlook the fact that streams have definite boundaries. The volume of flow, its type and direction, are decided by the levels and alignment of a stream’s bed and banks. Out on your driveway you set the hose nozzle to get the kind of stream that would do your job. Every time you pointed the nozzle in a different direction you changed the direction of the stream. I must admit that if time really does flow, its one-way flow does not appear to be directed by any beds, banks or nozzles.”
I raised another point. “The flow of water in streams varies with the season. Sometimes the water is high, sometimes low. Sometimes streams dry right up. But time has always kept right on coming. Through countless ages, how can it keep on coming this way? Its source must be inexhaustible. Yet only a few people who believe that time flows ever ask, ‘What or where is time’s source?’”
Michael canted his head and nodded thoughtfully.
“Furthermore,” I continued, “if time is a stream that flows, shouldn’t we be asking what keeps it flowing? You scientists consider that all movement results from energy flowing ‘downhill.’ Electrical current flows from high voltage to lower voltage and you think you know why. Heat moves from hotter places to cooler places, and you’re also pretty sure you know why. Water flows down from the hills to lakes and the sea, and you claim ‘That’s gravity.’ Even if water rises up when it evaporates, rain and snow fall downward. If time flows like a stream, for the stream of time, which direction is ‘down’? And why does it flow in that direction?”
For a few seconds neither of us said a word. I was trying to recall what I had ever heard or read about the direction of time. Then a striking contrast came to mind.
“You physicists tend to account for any present situation by events which happened in the past. You can demonstrate that when you interfere with any situation you can expect or even predict consequences. You know that what you do now can influence the way things will be in the future. For you, time flows from the past through the present toward a future.
“People who plan and create, however – architects, designers, artists, poets and writers – feel that time flows from the future into the present, the very opposite direction. For creative mentalities the future is an ever-filling reservoir of possible relationships. It holds fresh ideas which they can tap into, adopt and incorporate into the present realities which they are constructing. For them time seems to emerge from those hazy future possibilities into definite actual events before sinking into the unchanging past. As you know, particle physicists can somewhat understand this in terms of the ‘collapse’ of the Schrodinger wave function during an act of measurement which is intended to locate a subatomic particle. The significance of the wave equation which estimates the probability of finding an electron in a certain orbital may suddenly be abandoned or replaced by a definite actual locating of the elusive electron.
“So,” I concluded, “if time flows at all, there doesn’t seem to be any high-level consensus about which direction it flows.”
Michael chimed in. “As an astrophysicist I must think of time as moving from the past toward the future.” “The light that arrives here from a distant galaxy started on its journey aeons ago. Also, as you know, scientists carefully try to shield their experiments from all extraneous forces and factors that might interfere with the process under way. Only then can they be sure in the end that what happened to the setup was caused by what they themselves did, or allowed to be done, rather than by some other factor.”
I leaned forward a little. “Yet you have to admit that if interference with the experiment were not possible in the future, the experimenter wouldn’t be making sure that nothing untoward will actually happen. If something isn’t possible, it can’t happen, right? If it couldn’t possibly happen, taking proper precautions would be unnecessary.
“The future does seem to hold a lot of different possible states of affairs, any one of which could eventually become a present reality. However, past developments do have a lot to say about what can actually happen. I certainly couldn’t put a new roof on this house without first getting hold of a ladder and some roofing materials. Yet as I undertake the job, I have to take into account factors that could possibly upset my plans: the weather forecast, how I may be feeling after four hours in the hot sun, footwear safe for a sloping roof, how to handle unexpected visitors or telephone calls, and so on.”
I stopped to refill Michael’s coffee mug.
“You’re right,” he observed. “There are two contrary ways of understanding the direction of time. See! You are concentrating on the coffee which you’re pouring, but it’s only because my mug was empty that it’s able to receive what you’re pouring into it. Two ways of understanding the pouring of coffee – two ways of understanding time. Each view seems to be partly right. Each view by itself must therefore be somehow incomplete.”
After a pause, Michael suggested, “Maybe somehow time moves in both directions at once, like a rolling wheel does. When the top portion of the wheel is moving forward, the part in contact with the road is moving backward. When a figure skater whirls on the ice, one arm will be moving toward one side of the rink while the other arm is moving toward the opposite side.”
As I poured him some cream, he chuckled. “If you could believe that time flows like a stream, you could imagine eddies in the stream. Like a rolling wheel, part of an eddy moves in the downstream direction while the other part is moving upstream. I wonder if that’s what Isaac Watts meant by his ‘ever-rolling stream’.”
I decided not to rise to that bait and only shrugged. “We’ve been talking about time flowing between past and future. But what about the present? Although our breath, our blood and all of our other bodily fluids keep flowing as long as we live, the only mode of time we ever immediately and consciously experience is the present.
“While the world keeps changing with time, in our consciousness we ourselves seem to be stuck in an ever-present Now. Do we have within us some subtle, core constituent whose time simply persists? Can there be within us a kind of time-frame which remains steadfast while the events which we perceive come and go?
“Do we have here an intimation that, in association with us humans, there may be a different kind of time which is somehow beyond and independent of the transient events which we experience? Maybe a hint of something ‘eternal’? Despite talk about ‘the stream of consciousness,’ the permanent ‘nowness’ aspect of our consciousness is more like a standstill observation bridge than a flowing stream.”
Michael looked quizzical.
I continued tentatively, “Maybe there’s something about our Now-consciousness that is not really in the ordinary time-process at all. Are we humans linked in some special way to a steadier background against which the whole cosmic change process is taking place? If so, whatever it is that so constantly supports all personal consciousnesses must be universal, for everywhere that a conscious observer exists, it is always Now.”
Michael showed intense interest. But before he could say anything, Kay called from the kitchen, “Hey, you two! Come and see this.”
We jumped to our feet and followed her out onto the back porch. There spread across the whole sky in the late afternoon sun was an awesomely beautiful double rainbow.
For a while the three of us just stood there uttering incoherent exclamations of wonder and appreciation. Michael said quietly, “That rainbow looks so permanent, but its very existence depends on falling raindrops. While passing through, they reflect and diffract the sunlight. As long as the sun keeps shining at that angle and fresh raindrops keep falling, that rainbow will be visible.”
Since Michael left I have been wondering about the source of the steady light which perpetually illuminates our Now-consciousness. I think he may have had something quite profound in mind when he accounted for the lastingness of the rainbow by saying, “As long as the sun keeps shining…”