How Long Does The Present Last?
We all are familiar with the three main facets of time, those being the past, present, and the future, and we know that, in reality, only one of these exists at any one time.
The past has gone, the future hasn’t happened yet, and as the idiom goes, we live in the present. But just how long does the present last? How long does it remain a part of reality before it recedes into history, along with every other slice of time that we once could have called the present?
What is time?
There are many facets of my conscious existence that keep me awake at night, but the ones which tend to exhaust the grey matter the most are often what others might seemingly consider being so banal, trite, and obvious to the point where they are surely not even worth giving the time of day to, let alone the time of night. Time itself, being a classic example of this.
The subject of time has alluded me for much of my life. Like many, I’m sure, time is such an innate, ingrained part of existence, it can be difficult to give it the meaning, attention, and, yes, time, it deserves.
Of course, we all innately know what time is. It’s the thing that passes which makes everything older until it either dies or becomes unrecognisable from its original state. It’s what both creates and destroys. If we want to get technical, we can say, as many much more educated than myself in these matters would say, that it’s simply what allows entropy to occur. The transformation from order into chaos. So, there we go then, job done. That’s time in a nutshell, isn’t it? Well, no. It’s a very brief explanation of some of the consequences of time, but it doesn’t even begin to touch on just what time actually is.
There are many different interpretations of time, but again, they tend to focus on the results, outcomes, and effects of time rather than what time is. For me, try as I might, I find it difficult to truly comprehend the concept of Einstein’s spacetime, and I can’t be alone in this. The way I think of time is of it being the scaffolding on which space and all events within space cling onto. The bare bones of reality. Without that support, nothing can nor could ever happen or even exist.
Past, Present and Future
So, let’s for argument’s sake, assume that time works in the way we intuitively assume that it does, that which can be divided into three distinct facets — a past, a present, and a future. We can’t witness the past happening, but intuition dictates that the past did exist at one time because we are not only surrounded by the evidence of it, but we can also trust that that’s exactly how our memories are created. We know that reality, and as such, ourselves has not just popped into existence. Reality itself consists of creations, including ourselves, that must have come into existence in the past. The past is, if you will, the remnants, the fossils of a once present that is a present no more.
The future, however, is a different beast. More of a cousin to the past rather than a sibling. Its only similarity to the past, in that it is an aspect of time which also does not exist, is where the similarity appears to end. The only certainty we can say about the future is that it will happen. But the form in which it takes, or even if we ourselves will play a part in it cannot be determined with as much certainty. We can’t even be sure if we can change the future. Does free will exist? is a philosophical question that has dogged mankind since the days of Plato. Is the future pre-determined? How could we ever know?
So, given that we are assuming time works in the way we intuitively assume it does, with a past, present, and future, we can safely agree that only one of those components exists within the realms of reality. The past once existed but no longer draws breath and the future is yet to be delivered, which leaves us with only the filling in this time sandwich that the universe is slowly devouring. It is the only feature of time that tangibly exists as part of our true reality. The present.
This brings us to the topic of this article. If the past and future are not occurring, and only the present has any real meaning within our conscious reality, how long does the present last before it moves along the cosmic conveyor belt into the past, forever existing only as words on paper, memories in minds or remnants of creations which have already started to decay?
We can agree that every time you read one word of this article and move on to the next word, the action of reading that previous word is already in the past. So, should we agree that the present lasts for as long as it takes to read a single word of an article? Or does the definition of how long the present lasts only exist within context? For example, if we were to tell someone not to worry about tomorrow because today is all that matters, are we defining how long the present lasts as one day?
I accept that the present can, and often is, defined in context, but the point of this article is to explore a scientific definition of how long the present lasts, if indeed there is one at all.
Is time quantised?
I think it’s here that we need to start talking about whether time is quantised or not. That is, whether time flows smoothly from one moment to the next, or, on some kind of quantum level, does time move in tiny packets, jumping from one moment to the next without passing through the space between?
For those uninitiated with the concept of quantisation, you can think of it a bit like a person playing two notes on the same guitar string. They can either pluck the string and, as the string is still vibrating, move their finger up the neck of the guitar so that the note gets higher and higher in pitch, covering every possible pitch in between. This would be classed as unquantised. Something that moves smoothly from one position to another while interacting with every possible stage in between. Or do they pluck one note, remove their finger off the string, place their finger higher up the neck and pluck again, so that only two distinct notes can be heard? This would be classed as a quantised action. When actions ‘jump’ from one state to the next with no smooth transformation between them.
So, is time quantised? This question has been studied by greater minds than I over the centuries, and the general census amongst most physicians is that no evidence has ever been found that indicates time is quantised. It appears that the finger of time does indeed slide up the neck of reality from one event to the next, without removing the contact from the string itself. That’s not to say that time has definitively been proven not to be quantised. It’s just that no evidence has ever been found to show that it is.
Of course, if time were quantised, this would make the question of how long the present lasts much easier to answer. We could define it as the time it takes to jump from one ‘event’ of time to the next, however short that ‘event’ may turn out to be. And it would, of course, be extremely short.
But in the absence of any definitive evidence of time being quantised, we are going to have to think more creatively if we want to answer the question of just how long the present lasts.
Calculating the speed of present
To o my mind, we only need two values to measure the length of the present. A value that represents space, or distance, and one which, naturally, represents time.
For time, we would have to turn to the fastest thing in the universe that we currently know of. That being the speed of light. But remember, the speed of light is not simply a speed at which light travels, although, of course, this is what it is, it represents so much more than that. It is the cosmic speed limit at which reality itself appears to flow. It is the rate at which the universal clock appears to tick. It is the link between matter and energy. The meaning behind perhaps one of the most famous equations in all of science, Einstein’s E=Mc², with c representing the speed of light.
So, we have a theoretical speed with which to work, which we could use to give us something to work with when trying to define the length of the present. I mean, we already use the speed of light to measure both time and distance in the form of light years.
Now, what about distance? In the same way that the universe has a universal speed by which nothing can go faster and as such, appears to govern our reality, do the physical laws of nature also provide a distance with a similar quirk that gives it a meaning that no other distances have?
For those that may not already be aware, it turns out that there is. The Planck length, discovered by the physicist Max Planck around the end of the 19th century. I won’t even begin to pretend to be an expert in this extremely complex field of physics and mathematics. I’m not an expert in either, my only qualification being one of sheer inquisitiveness and fascination for this conscious reality that I appear to be a part of, but in short, it is, according to my understanding, the smallest possible distance that could ever exist in our universe, according to the laws of physics as we currently understand them. When I say could ever possibly exist, what I mean is could ever possibly exist with any meaning. Any length smaller than the Planck length would be so small that it would be impossible to have any meaning in any possible way, and therefore would be inconsequential on every level of reality. It would contain such little information if any, that it would be indistinguishable from something that simply does not exist. Of course, I could Google it and give you the actual distance of a Planck length, but I know that unless you are literate in this field, it would mean as little to you as it does to me. The human brain is simply not wired to conceptualise certain mathematical truths, and this is one example of that.
So, just how long does the present last?
So, in short, we have the fastest speed in the universe, the speed of light, and we have the shortest possible distance, the Planck length. Now, to measure just how long the present lasts we need an event. We already know that time is probably not quantised, and that time moves in a smooth, linear fashion, so to find just how long the present lasts, we need to find the shortest event that could possibly occur in the universe.
There is only one answer to this. It would be the time it takes for the fastest known speed in the universe to travel the shortest distance possible. We are, in effect, talking about the time it takes for something moving at the speed of light to travel a Planck length. This would be a length of time that would be impossible to break down any further. The Planck length is already the shortest distance possible, and nothing can travel faster than the speed of light. It therefore stands to reason that the shortest event that can ever happen is the time it would take for a photon of light to travel a Planck length.
I’m not even going to try to work out just how fast an event that would be. There are greater minds than mine that can do that, but I’m sure we can all agree that it would be one of the smallest, or largest, depending on your point of view, numbers in all of mathematics. It would be a length of time so unimaginably small, it would far eclipse notions such as there being more stars in the sky than grains of sand on the earth. It would be a length of time so short that, if it were any shorter, it could not possibly exist.
The most fascinating facet of all of this isn’t quite so much that the present appears to last for such a brief, unimaginably short period, it’s that this tiny slither of reality is the only aspect of time, and as such, our reality, which exists. The present is the only aspect of time with reality. The present isn’t something that has already happened and can no longer be changed. It isn’t the unknown and uncertain future that is yet to happen. The present is all that we have. It is reality itself. Yet its passing is so inconceivably, unimaginably brief, that if it were to be any shorter, it could not possibly exist.
It is a common belief that the past has gone, the future is yet to happen, and that all we have is the here and now, the present. The concept being that the past and future are unimportant, or at least, less important than the present.
But, when we consider all three of the facets of time, the past, the present, and the future, we could say, that it is the present which, I may have demonstrated, is the most meaningless of them all.
