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Facts of the Matter Richard Brill |
Does anybody really
know what time it is?
"If no one asks me, I know what it is. If I wish to explain it to him who asks me, I do not know. Yet I say with confidence that I know that if nothing passed away, there would be no past time; and if nothing were still coming, there would be no future time; and if there were nothing at all, there would be no present time."-- St. Augustine in "Confessions" around A.D. 400
We know what time it is, but do we know what time is? It's about time we learn about time.
For something that is such a factor in our lives, and controls them to a large degree, it is curious that we know so little about what time really is. There are many more questions than answers, and the answers are largely speculation, although we know much more about time now than at any previous time in history.
The nature of time has baffled all who have considered it, from the beginning of time.
Philosophers have speculated about the nature of time for at least 2,500 years, without satisfactory resolution of the issue. They have discussed whether time had a beginning, whether it might end, whether it is an objective feature of the real physical universe, or a subjective product of experience. There has been debate about whether time flows like water in a river, whether the future and past are real or whether only the present is real, or if it is all subjective and only exists in the mind that is capable of symbolic thought and planning.
Does time exist when nothing is changing, or is it only awareness of change that defines it? Is it the fundamental forces, such as gravity or electric charge, that give time its one-way arrow?
One would think that after two-and-a-half millennia of speculation, and three-and-a-half centuries of science, that someone would have figured it out!
Today there are many theories about the nature of time, and it would be impossible to recount them all. There are entire university courses on the nature of space and time. Philosophers continue to speculate and physicists write equations that define space-time, trying to dissect this thing that can be measured and counted but not explained.
Aristotle, if not the greatest then surely the most prolific philosopher of ancient Greece, considered the nature of time in his writings on physics around 330 B.C. He characterizes the difficulties that have befuddled, bewildered, mystified and perplexed the greatest minds of humanity ever since.
Aristotle's discussion focuses on three key problems:
>> Does time exist?>> What is the nature of the present, the "now" as he called it?
>> What is the nature of time itself?
It is natural to think of time as consisting of the past, present, and future, but Aristotle noted that the past is gone and no longer exists, and the future has not yet happened. The present is just a point that separates past from future, so it does not exist if the past and future do not. Aristotle found this to be quite a conundrum.
The past is gone, the future never arrives, and the present is just a separation between the two. How can time exist if none of its parts do?
This is the basis of the frustration that Augustine expressed 700 years later.
Part of the problem in comprehending time is that we use the word in many different ways. It seems that time is not a single concept, but rather a group of related concepts. It is the intuitive "if no one asks me" part of Augustine's conundrum.
The time of the physicist is not the time of the poet. The calendar won't tell us how long to cook the rice, but it can tell us when to plant it.
Having a good time is not the same as "good times," and is not the same as "what time is the concert." A "time out" in a basketball game is not the same as the four-four time of the music the band plays while the game clock is stopped.
We seamlessly move from one concept of time to another, discarding one concept in favor of another as needed, all the while maintaining the illusion that time is a single concept that needs no explanation because we know what it is.
We accept that the present becomes the past even as it is becoming the future. We are so culturally attuned to our own concept of time that we don't realize that our conceptualizations of time are culturally dependent. For example, the language of the Hopi Indians contains no words that refer to time in a linear fashion; their verbs have no tenses. In the Hopi world, time is a continual present that contains everything that has ever happened.
Historically, the observation of the cyclic nature of time led to the calendar, which could predict with varying degrees of success when events in the sky or seasonal changes would take place.
The earliest clocks were sundials that functioned in tune with natural events, reflecting and reinforcing the notion that time was cyclic and intrinsic to nature. Calendar time, refined through the ages did, and still does likewise.
Eventually people learned to use other means, crude and inaccurate as they were, to measure time in cycles of man-made periodicity, fashioned from the cycles of nature, such as the time required for a candle to burn, or for sand to drain through the waist of an hourglass.
It was not until the middle of the 17th century that Christiaan Huygens in Holland invented the pendulum clock that for the first time could be made to "keep" time accurately and to tick away as long as desired. This single invention greatly influenced the changeover from the cyclic view of the ancients to our modern linear view of time.
Later in the 17th century, Isaac Newton published his famous book, "Principia," in which he stated his laws of motion and gravitation, initiated the science of physics and began the modern scientific era. He also defined the modern concept of linear time: "... absolute, true and mathematical time, of itself and from its own nature, flows equably without relation to anything external."
Newton's physics describes duration as an absolute property, implying it is not relative to the reference frame of the clock. That concept defined the scientific paradigm of the "flow" of time until Einstein displaced it two-and-a-half centuries later with his theory of relativity, which revolutionized once again way we conceptualize time.
Einstein discovered that time is not uniform and steady. The clocks of two observers tick at different rates if they are in motion relative to one another, or in the presence of a strong gravitational field. Fortunately this doesn't affect us in our daily lives, since the effects are negligible until speeds get up into the thousands-of-miles-per-second range -- far beyond the speed limit of anything other than subatomic particles.
It may seem that these scientific and esoteric concepts of time are not relevant to us in our daily lives, but the same might have been said of sundials in ancient times when anybody could look at the sky to see where the sun was. People in ancient Egypt could have had no hint of the role that global positioning (GPS) satellites, which rely on nanosecond precision, would have in our world.
It appears that human awareness of time may be an effect of consciousness: The ability to distinguish the sequence of events, and the ability to imagine events that have not happened yet.
There is a flow and sequencing of events in nature, but does this ordering of events by itself constitute time in the absence of intelligent awareness of it?
Rocks undergo physical and chemical changes as they weather. Certain kinds of events don't happen in reverse: Rust does not spontaneously turn into shiny iron; a deck of cards scattered in the air will not spontaneously gather itself into a neat pile.
Time may be a biological phenomenon whether or not consciousness is involved. Built into each and every cell, whether it be human or cyanobacteria, is a clock that tells the cell when it is time to reproduce, and in multi-cellular organism when it is time to differentiate into specific types of cells. These kinds of changes will not happen spontaneously in the same way that a landslide will.
All life on Earth has been influenced by the 24-hour rotation and the day-night cycle, and biological clocks have evolved to coordinate biological processes, which are chemical in nature at the most fundamental level.
"Circadian" rhythms (from "circa" -- about, and "dies" -- a day) are one macroscale result of the these biological clocks. Circadian rhythms persist with a period close to 24 hours even in the absence of environmental information.
It is not just sleep and eat cycles. The circadian clock regulates many aspects of metabolism, physiology and behavior in humans and other organisms.
A system of linked feedback loops regulates the 24-hour period by controlling the transcription of a small number of "clock" genes. Circadian rhythms are outwardly very similar in all species but the genes that make up the clock mechanisms in animals, plants, fungi and cyanobacteria are quite different.
Time, like gravity, is one of those things that we don't know the nature of, but will continue to influence us in ways that we take for granted or are unaware of. We know how to keep very accurate time, but we don't know much about time.
By the way, what is the time?
Richard Brill picks up where your high school science teacher left off. He is a professor of science at Honolulu Community College, where he teaches earth and physical science and investigates life and the universe. He can be contacted by e-mail at rickb@hcc.hawaii.edu