How long does a "Now" last?

How Long does a Now Last?

They say to always start out with a joke, so here's a little fowl humor: Did you hear about the two chicken hatchlings, fresh out of their shells, already wheeling and dealing? "My peeps will call your peeps," the one male said to the other, "and we can do lunch or something." "Just make sure," the other cheeped, "that there'll be plenty of food and chicks around." This now concludes the entertainment portion of our presentation. Thank you.

No discussion of this particular topic would be complete without some question as to what lengths, periods, intervals, or increments does time describe, much as a draftsman’s compass scribes a circle on paper. What size is the circle of time? A query which is more aptly stated: how small is a single byte (or bit) of time itself? What part of a single second can no longer be sliced, diced, or divided further?

For those who already read or perused the essay about the Dichotomy Paradox, they will recall how Planck units are the logical extension of the basic Planck Length, which is the label assigned to what is thought to be the tiniest, still measurable but no longer divisible space in the known universe. The following consideration and subsequent evaluation of this smallest piece of time will therefore seem almost obvious and entirely appropriate.

For readers not familiar with a Planck Length, it is the theoretical limit on empty space, and how miniscule it can be and still exist as a gap of some sort. Any closer together and two or more things would occupy the same space; thus a Planck unit is where one thing is touching another, but not quite. Think of it as a span so tiny that it can no longer be cut into anything smaller. The "tock" without the "tick" if you will.

Because Planck units pertain to an aspect of space, then they must, by their very nature, involve the inseparable element of time -- as in space-time. It has also been determined that space-time generally refers to space-motion, meaning that in order for time to exist, space is measured in terms of some distance traveled, during a given period of time. Since everything is space is moving, time is always associated (normally) with motion.

Painful but necessary: The requisite "fine-print".

Before going further, allow me to paraphrase what Wikipedia has to say on the matter:

One Planck-time is the time it takes a photon traveling at the speed of light to cross a distance equal to one Planck length, or unit. Theoretically this is the smallest measurement of time that will ever be possible. Within the framework of the laws of physics (as we understand them today), for time intervals that are less than one Planck-time apart (an even smaller increment), we can neither measure nor detect any change. In other words, anything littler and we're lost.

The idea of Planck-time comes from a field of mathematical physics known as Dimensional Analysis, which studies units of measurement and physical constants. The Planck-time is the unique combination of the gravitational constant G, the relativity constant c, and the quantum constant h, to produce a constant that incorporates units of time. Oh, sure, that makes perfect sense.

For processes (or events) that occur in a time period less than one Planck time in length, such a dimensionless quantity is greater than one. Well, duhhh, everybody knows that. Dimensional Analysis suggests that the effects of both quantum mechanics and gravity would be important under these circumstances, requiring a theory of quantum gravity. All scientific experiments and human experiences happen over billions and billions of billions of Planck-times, making any events happening at the Planck scale hard to detect. Gee, you think?

Introducing Phreddy, the phriendly, inphinitesimal photon.

Okay, so I know all that sounds ridiculously complicated. We get that. But at it’s core lies some pretty basic stuff that gets a lot less complex, the more one digs around in it, like so much mud. Get dirty enough, and some of it is bound to stick.

Notice too, how Planck-time requires an object in-motion, in this case a photon, to cross a certain distance (one Planck unit) in order for time to exist as part of the equation. Obviously these photon things are pretty small themselves if they can traverse a gap that is theoretically gapless. That’s not a real word, but it seemed to fit.

So how long does a now last? Well, according to Wikipedia and professor Max Planck, a German physicist who lived at the turn of the century, the answer seems simple enough. It’s obviously the amount of time it takes for one of these photon thingies to cross from one side of a Planck Length to the other. Why did the chicken cross the road? In order to get there, it would seem.

Let’s see if we can break this all down a bit more and view things from a slightly different perspective. But not change them so radically that we violate the spirit and meaning of the basic definition itself.

Suppose that we look at a single Planck-time in such a way that it represents an actual span of empty space, with only emptiness in-between. Phreddy, the phriendly photon, is going to join in and help us figure things out. Everybody say hello to Phreddy.

Phred’s a hard guy to get ahold of. The reason is because he usually exists either in the past or in the future. As we prepare for our experiment, Phred is perched on the one edge (the right side, say) of a Planck unit where a bottomless crevasse separates him from the other side, the other edge, in a manner of speaking.

Since we want to observe the elapsing of an actual now, Phred is currently standing on the far side of the gap, in the future, goggles on, scarf, ready to go. And he’s off! Wow, that was fast. Still panting, Phred has joined us on the other side, in the past. As he catches his breath, the instant-replay cameras show us Phred’s spectacular jump in slow motion.

Even at this speed, Phred is nothing but a blur, and in real time, so to speak, the little fella isn’t even visible. But there you have it. The scientists in the crowd have all used their pocket calculators and determined, as a mathematical equation, the exact amount of time it took for Phred to cross over, from the future to the past – with the now in-between.

Some shouting and yelling can be heard, however, among the scientists themselves. They’re arguing over whether Phred did indeed jump from the future into the past, or do we have things backwards, as some are claiming; that Phred jumped from the past into the future, with a now in the middle. Is it all the same, or is there a difference?

If the future hasn’t happened yet, so goes the counter argument, then we are constantly moving from the past into an ever-elapsing (unfolding) future that never truly exists as anything at all. Other than a prediction of one kind or another.

A now really does happen, however, and in the span of a single Planck-time, is converted almost instanteously into a memory or past event. Past events have repercussions and ramifications that impact the present, whereas futures can only be anticipated and prepared-for based on probabilities and predictions.

The present, by the way, if defined, seems longer than a Planck-time. We have a fairly decent grasp at this point on how long a now lasts, and no matter what, a now connects past to future or future to past, depending on which side of the gap one comes down on.

But the term, present, seems to possess its own quality of being. No one ever defines the present except in the most simplistic of terms. I think it’s something special and deserving of its own special definition. One thing is for sure at this point: a second is a really long time.

I was curious as to where the increment of one "second" came from in the first place, and not surprisingly it all derives from mathematicians, astrologers, astronomers and the like. Men had to make sense of the seasons and the different times of the day, so all manner of timed intervals were put in place at one time or another, in one place or another.

Apparently it wasn’t until the pendulum clock was invented, where the swinging arc described by a pendulum, from one end of its full sweep to the other, represented a pretty reliable (and consistent) span of time, and gave us our modern second. Which is quite literally the time between "tick" at one end, and "tock" at the other. That still doesn’t explain what’s meant by a term like present, expecially when compared to (inserted between) other terms like past and future.

I think we’re all in agreement that of the three, future is the least tangible, certainly the least reliable, and for all intents and purposes, doesn’t exist except as a linguistic device or construct. That leaves us with only the past and present to work with. For the record, allow me to clarify or distinguish now, from present, and state emphatically that they are not the same. Not in my never-to-be-humble opinion.

One reason is because now, in terms of something happening -- a fleeting, single moment -- refers to a solitary event or process, which in the case of time, is the previously defined Planck-time-unit. And with respect to reducibility, represents a one-of-a-kind affair. By that I mean to refer to what I call a solitary elapsing of time, an elapsation, that cannot be reduced any further.

While a Planck time may be thought of as the smallest interval of time, perhaps "the present" exists as the largest unit of time that can still be considered as an individual, albeit divisible, increment of time. The reason such differentiations are important, stems from the premise that since language is the only tool we have for discussing abstract ideas, we should refrain from a certain sloppiness that would allow for the overlapping of some terms, as if they were interchangeable when they are not.

Since now possesses a very specific definition as outlined in this essay, the word present can have a number of different meanings and connotations. More typically it refers to a continuous stretch of time that is neither past nor future. Present-day might span years, even decades of time. Contemporary, a synonym for present-day, usually refers to a recent period that may still cover years or decades of time.

By comparison, a present moment might well describe an ongoing sequence of individual now events, all of which transpire over an indeterminate period. If we are to be precise (and concise) in our analysis of the world (and the universe) the language we use to talk about our observations must be as precise and concise as possible. This is especially crucial when a multitude of different languages are used to describe identical situations. A strong case is thus made for the adoption of a single language when the complexities of the cosmos are involved.

So how long does a now last? I bet the question doesn't seem quite so absurd now -- if you've read this essay. Not touched upon in my composition here are the interesting ways in which time is likely affected by one's physical location in a galaxy. Or how time slows down when velocity increases.

You know, that whole clock-in-orbit business where time runs a tad slower than its counterpart back on Earth? Then think in terms of how Planck time itself must be influenced in some way, as clocks slow down with increasing speed. Talk about heaping discombobulation on top of confusion.

The suggestion in such scenarios is that Phreddy, our phine little photon phellow (okay, no more, I promise) moves slower -- under certain conditions -- across a Planck unit of space. Thus might it not, under other conditions, move more rapidly across? That's exactly what happens when you live in different parts of a galaxy, where some sections move at vastly different rates of speed than do others.

If you don't get bogged down in the jargon or take all of this too seriously, there's a lot of fun to be had thinking about how time plays into and out of a lot of different situations. All of them based on varying degrees of motion and movement through space -- and especially as found inside galaxies. (okay, so my idea of fun might be a little strange)

There's just no end, however, to the frivolity of it all, if you happen to like this sort of thing. I think it's safe to assume most people don't, and if you read through all of this, it's because you were either really, really bored, or figured there's was some great punchline at the end.

Since this is likely my last essay for a while, that alone may satisfy those in need of comic relief. I've covered most of the big stuff and as illustrated here, a lot of the little stuff as well. Time for me to go back and revise, edit, and make sure all the other essays are as comprehensible as possible. That's asking a lot of myself. And especially of the poor souls who, at some point, will try to wade through some or most of what I've been bloviating about.

I doubt that from here on, though, you'll think of time in the same way as before. And if I've succeeded in messing you up, at least a little in that regard, then I'll consider my efforts as both worthwhile and timely.