Consider a glass containing club soda and ice cubes. At first, there is definite structure. Ice is separate from the liquid and so are the bubbles, and the ice and liquid have different temperatures. But return later and the ice has melted, the soda has gone flat, and the contents of the glass have merged into a structureless oneness. Barring evaporation, no further change will occur.
This evolution away from structure and activity toward sameness, randomness, and inertness is entropy. The process pervades the universe. According to nearly all physicists, it will prevail cosmologically in the long run. Today, we see individual hot spots like the Sun releasing heat and subatomic particles into their frigid environs. The organization that now exists is slowly dissolving and this entropy, this overall loss of structure, is on the largest scales a one-way process
.
In classical science, entropy does not make sense without a directionality of time because it is a non-reversible mechanism. In fact, entropy
defines
the arrow of time. Without entropy, time need not exist at all.
But many physicists question this “conventional wisdom” regarding entropy. Instead of the act of structure-loss and disorganization representing a concrete directionality to time, it can just as well be seen as a demonstration of random action. Things move. Molecules move. They do so in the here-and-now. Their motions are haphazard. Before long, an observer will notice the dissipation of the previous organization. Why should they then assign arrows to it? Shouldn’t we regard such random entropy as an example of the nonessentiality or reality of time, rather than the other way around?
Say we have a room full of oxygen, and an adjacent one filled with pure nitrogen. We open the door and come back a week later. Now we find two rooms, each with a well-mixed combination of both gases. How shall we conceptualize what happened? The “entropy” view says that “over time” there was a loss of the original neat-and-tidy organization and we now have a mere randomization. It is not reversible. It demonstrates the one-way quality of time. But the other view is that the molecules just moved. Movement is not time. The natural result is a mixing. Simple. Anything else is just human imposition of what we consider to be order.
Seen this way, the resultant entropy or loss of structure is only a loss in our own minds’ way of perceiving patterns and order. And boom, there goes science’s final need for time as an actual entity.
Time’s reality or lack thereof is certainly an ancient debate. The actual answer may be mind-bendingly more complex because there may be many planes of physical reality, which, like even our purely subjective sense of time, may
appear
to operate on some levels (for example, biological life) but be nonexistent or irrelevant on others (for example, the quantum realm of the tiny). But the bottom line is always
appear
.
As an interesting side note, physicists looking into the time issue in the past two or three decades have realized that just as all objects
must have shapes, if time existed it would need a
direction
of flow. This has given rise to the issue of an “arrow of time” that can alter its course. Even Stephen Hawking once believed that if and when the universe starts to contract, time would run backward. But he later changed his mind, as if to demonstrate the process. In any event, time running backward (though ultimately a non-starter) was not as screwy as it may have initially seemed.
We protest because we think that it means effect would precede cause, which never can make sense. A serious car accident would become a macabre affair where injured people instantly heal without a blemish while their wrecked vehicle leapt back while uncrinkling and repairing itself seamlessly. This is not only ridiculous, it doesn’t accomplish any purpose, such as, in this case, instruction in the evils of using a cell phone while driving.
The usual answer to this objection is that if time ran backward, everything including our own mental processes would operate in the same new direction as well, so we’d never notice anything amiss.
Such endless unanswerables and seeming absurdities come to a blissful end, however, when time’s nature is seen for what it is—a biocentric fabrication, a biologic creation that is solely a practical operating aid in the mental circuitry of some living organisms, to help with specific functioning activities.
To understand this, consider for a moment that you are watching a film of an archery tournament, with Zeno’s arrow paradox in mind. An archer shoots and the arrow flies. The camera follows the arrow’s trajectory from the archer’s bow toward the target. Suddenly, the projector stops on a single frame of a stilled arrow. You stare at the image of an arrow in mid-flight, something you obviously could not do at a real tournament. The pause in the film enables you to know the position of the arrow with great accuracy—it’s just beyond the grandstand, twenty feet above the ground. But you have lost all information about its momentum. It is going nowhere; its velocity is zero. Its path, its trajectory, is no longer known. It is uncertain.
To measure the position precisely, at any given instant, is to lock in on one static frame, to put the movie on “pause” so to speak.
Conversely, as soon as you observe momentum, you can’t isolate a frame—because momentum is the
summation
of many frames. You can’t know one
and
the other with complete accuracy. Sharpness in one parameter induces blurriness in the other. There is uncertainty as you home in, whether on motion or position.
At first it was assumed that such uncertainty in quantum theory practice was due to some technological insufficiency on the part of the experimenter or his instruments, some lack of sophistication in the methodology. But it soon became apparent that the uncertainty is actually built into the fabric of reality. We see only that for which we are looking.
Of course, all of this makes perfect sense from a biocentric perspective: time is the
inner
form of animal sense that animates events—the
still
frames—of the spatial world. The mind animates the world like the motor and gears of a projector. Each weaves a series of still pictures—a series of spatial states—into an order, into the “current” of life. Motion is created in our minds by running “film cells” together. Remember that everything you perceive—even this page—is actively, repeatedly, being reconstructed inside your head. It’s happening to you right now. Your eyes cannot see through the wall of the cranium; all experience including visual experience is an organized whirl of information in your brain. If your mind could stop its “motor” for a moment, you’d get a freeze frame, just as the movie projector isolated the arrow in one position with no momentum. In fact, time can be defined as the inner summation of spatial states; the same thing measured with our scientific instruments is called momentum. Space can be defined as position, as locked in a single frame. Thus,
movement through space
is an oxymoron.
Heisenberg’s uncertainty principle has its root here: position (location in space) belongs to the outer world and momentum (which involves the temporal component that adds together still “film cells”) belongs to the inner world. By penetrating to the bottom of matter, scientists have reduced the universe to its most basic logic, and time is simply not a feature of the external spatial world. “Contemporary science,” said Heisenberg, “today more than at any previous time,
has been forced by nature herself to pose again the old question of the possibility of comprehending reality by mental processes, and to answer it in a slightly different way.”
The metaphor of a strobe light might be helpful. Fast flashes of light isolate snapshots of rapidly moving things—like dancers in a disco. A dip, a split, a snap becomes a still pose. Motion is suspended. One
still
follows another
still
. In quantum mechanics, “position” is like a strobe snapshot. Momentum is the life-created
summation
of many frames.
Spatial units are stagnant and there is no “stuff ” between the units or frames. The weaving together of these frames occurs in the mind. San Francisco photographer Eadweard Muybridge may have been the first to have unconsciously imitated this process. Just before the advent of movies, Muybridge successfully captured motion on film. In the late 1870s, he placed twenty-four still cameras on a racetrack. As a horse galloped, it broke a series of strings, tripping the shutters of each successive camera. The horse’s gait was analyzed frame by frame as a series. The illusion of motion was the summation of the still frames.
Two and a half thousand years later, Zeno’s arrow paradox finally makes sense. The Eleatic School of philosophy, which Zeno brilliantly defended, was right. So was Werner Heisenberg when he said, “A path comes into existence only when you observe it.” There is neither time nor motion without life. Reality is not “there” with definite properties waiting to be discovered but actually comes into being depending upon the actions of the observer.
Those that assume time to be an actual state of existence logically muse that time travel should be valid as well—and some have misused quantum theory to make this case. Very few theoreticians take seriously the possibility of time travel or of other temporal dimensions existing in parallel with ours. Aside from the violations of known physical law, there’s this little detail: if time travel were
ever
possible, so that people could journey into the past, then—where are they? We’ve never been faced with tales of unexplained people arriving from the future.
Even time’s seeming rate of passage varies in perception and definitely alters in actuality. We point telescopes to places where we can
see
a more lethargic unfolding of time à la relativity, and also observe places as they existed billions of years ago. Time’s makeup seems as strange and elusive as that of sausages.
Let’s try to clarify one common alteration in the passage of time with a simple thought experiment. Pretend you’re blasting off from Earth, looking out your rocket’s rear-facing window, telescopically observing the people near the launch pad who are applauding the successful liftoff. Each moment you are farther from them, so each moment their images have a longer distance to travel to your eyes and are therefore delayed, arriving significantly later than the last “frame” of the movie. Result: everything appears in slow motion, their applause dishearteningly lukewarm. Nothing speeding away from us can fail to appear in slow motion. And because nearly everything in the universe
is
receding, we’re peering at the heavens in a dreamy kind of mandatory time-lapse photography; the unfolding of nearly all cosmic events takes place in a false time frame.
This was exactly how the speed of light was discovered, by a Norwegian named Ole Roemer, more than two centuries ago. He noticed that the moons of Jupiter slowed down for half the year, and, realizing that Earth was then moving away from them in our orbit around the Sun, was able to calculate lightspeed to within 25 percent of its true value. Conversely, those satellites would seem to speed up for the other six months, just as inhabitants of an alien world would go about their business at an accelerated fast-forward, Charlie Chaplin pace as viewed by approaching astronauts.
Superimposed on these illusory yet nonetheless inescapable distortions is the actual slowdown of time at high speeds or in stronger gravitational fields. This is not merely something we can shrug off with facile rationalizations, like an errant spouse’s late homecoming. This zooms to the far end of peculiar.
This
time dilation
effect is minor until one nears the speed of light, then it becomes awesome. At 98 percent of lightspeed, time travels at half its normal speed. At 99 percent, it goes just one-seventh as fast.
And we know this is true; it’s real, not hypothetical. For example, when air molecules high in our atmosphere get clobbered by cosmic rays, they smash apart like the breaking of a stack of billiard balls, their innards spewing earthward at nearly the speed of light. Some of these subatomic bullets pierce our bodies, where they can strike genetic material and even cause illness.
But they oughtn’t to be able to reach us and do such villainy; this atomic material is so short-lived that these muons normally decay harmlessly in a millionth of a second—too quickly to be able to travel all the way to Earth’s surface. They manage to reach us only because their time has been slowed by their fast speed; an extended fantasy world of false time allows them to enter our bodies. So relativistic effects are far from hypothetical; they have often brought poisoned offerings of death and disease.
Travel in a rocket at 99 percent the speed of light and you’ll enjoy the consequential sevenfold time dilation: from your perspective nothing has changed; you have aged a decade in ten years’ worth of travel. But upon returning to Earth you’d find that seventy years have passed and none of your old friends are still alive to greet you. (For the famous formula that lets you calculate the slowdown of time at any speed you care to consider, see the Lorentz transformation in Appendix 1.)
Then the truth rather than the theory will have hit home: ten years can really pass for you and the rest of the crew, while
at the same time
seven decades elapse back on Earth. Abstract arguments then fail. Here a human lifetime has elapsed while there it’s only been a decade.
You might try complaining that time is supposed to have no preferred state—how, then, can nature determine who should age faster or slower? In a universe without privileged positions, couldn’t you claim to have been stationary while the Earth moved away and then came back? Why shouldn’t Earth’s inhabitants be the ones who aged more slowly? Physics provides the answer.
You were the one who has lived longer, therefore the answer must lie with you. And it does: it was you who felt the acceleration
and deceleration forces of the trip. So you cannot deny that it was you and not Earth that made the voyage. Any paradox is nipped in the bud; the one who made the trip also knows who should experience the slowing of time.