13 | The Physics of Time

Welcome to the Cow Behind the Barn: A podcast exploring humanity, the world, and the divine, as experienced and interpreted by an artist. I’m Kevin Caldwell, a Co-Finder of the Table Collective.

I shouldn’t be surprised that physics is revealing to me that time is not what I thought it was for most of my life.

In the last Episode I focused on what I call the pragmatic and practical ways of seeing time. The way that daily life just requires us to use and measure and speak of time.

The next Episode will explore philosophical approaches to time, including ways of understanding time within some of the world’s religious heritages.

But physics and time, or the physics of time, is the focus of this Episode.

Before I start to portray what I have been gleaning from physicists about time, which will be done in prose, I want to turn to poetry, a portion of a piece I published in my Cow Behind the Barn book, called, “Three Ways of Seeing a Doorway Between Two Hallways.” 

I wrote it long before I began to dig into what physics might say. The poem began as a way of reflecting on an experience I had one morning, seeing my wife as she passed from one hallway, into another, through a doorway that connected both hallways to the room where I was sitting as she passed. As such it was like a moment caught in a frozen frame of time. And it caused me to reflect in three ways about the same event, which I referred to as three ways of seeing.

I am leaving out the first “way” from that piece, which I called “seeing in prose.” But I will share the other two, seeing in Haiku and seeing in blank verse.

 

Ways of Seeing a Doorway Between Two Hallways

Seeing in Haiku:

 

She passed the doorway

Eyes met, hands waved, and then gone

I am here, alone

 

Seeing in Blank Verse:

 

From behind a wall the sounds of a door

And bare feet in a hall.

Through the doorway, rounding a corner, 

She passes from one unseen to the next.

Our eyes meet, hands wave,

We are mouthing soundless words of greeting in the grey light.

The moment fleeting, gone.

I am still here, alone.

 

The poem is a way of describing the present (the doorway), and the past and the future (the two hallways). It is experiential. And If I had to summarize a view of time from it I would say things like:

• In the present moment, there are sounds from the past (a door, feet in the hall); the sounds, metaphorically, are the events of the past, and they are real, and present, but not fully.
• The future is much more mysterious, unseen, unknown.
• The present passes and is gone. As do the people in our present moments.

That is how I described in poetry the experience inspired by an actual event in my life. What will physics have to say about it?

In order to answer I will arrange the questions about time I had asked in the prior Episode so that they give me some sense of structure for my material. I have come up with two questions that are like big buckets into which the other questions seem to fit.

The two big questions are: Is time absolute? And what is the nature of the past/present/future?

 

Two Big Questions

Is time absolute? 

Includes questions such as whether time is the same everywhere, and the same in its relationship to everything, and to everyone? Is time the same, dare I say it, all the time? 

What is the nature of past, present, and future?

This includes questions such as, does time pass, or move, or is that just the way we experience it? Is it more accurate to say that we pass and move through time?

Does time only go in one direction? Or, do we only go in one direction?

Do times other than the present moment exist? Is “this present moment” the only real time? Does only now actually exist? Do the past and the future have any existence? 

And the present? How long or short does a point in time need to be to qualify as a present moment? One second? A nano-second? Does the present moment ever exist? Is there really a “now?”

Now, there is a third bucket as well, which I might call “the relationship of time and consciousness.”  But that is something to be looked at in, well, the future!

So, on to the physics of time. 

 

Physic and Time: Is Time Absolute?

If time is absolute, then time is the same everywhere, for everyone, that is the definition of “absolute.” And it is always the same. 

However, physics tells us that time moved twice as slow 14 billion years ago, and 12 times slower 32 billion years ago. Time is faster now than it was in the past, and it seems time will be faster in the future than it is now. 

Time is not the same at all times. 

Is time the same in all places? 

After Einstein there is a near consensus among physicists that time flows at different rates depending on various factors. One of those factors is gravity. Gravity is different depending upon where we are in the universe. So, time is not the same in every place.

Is time the same everywhere and always? No. We already have a simple answer to the question whether time is absolute.

Time is local (to a place and to a moment). In a very real sense then, time is “personal,” subjective. I don’t mean that it is subjective in the sense that we each make it up, but in the sense that each person will experience time differently depending upon where they are, and “when they are” or were, or will be.

What we call time is really the result of an entanglement between a constantly changing universe and we who, at different times and places, are experiencing it. Time and the subject experiencing it are entangled. In fact, I think the nature of time is that entangled experience.

One factor that gives us the illusion of time as a “real thing” is the fact that we have created and use rather arbitrary methods of measuring our experiences of change. We have named those measurements seconds, and hours, and months, and these definitions begin to take on a sense of essential reality for us, giving the impression of time as an absolute “thing.”

Past and present and future are part of that experience, but if time is not absolute then neither are they. Exploring what I mean by that begins to bleed into the next big question about the nature of past, present, and future. 

 

Physics and Time: What is Past, Present, and Future?

If there is no objective absolute “cosmic” time, then there is no cosmic “present.” If time is different in different places and at different times, then what we call “now” is going to be different in different places and times as well. It follows that the same will be true for the past and the future.

That is not, of course, how we normally speak of or experience time. For most of us, I think it is safe to say that our most common way of thinking about past, present and future might be something like this:

The past is full of things that used to be the present, and when they were the present, they were real. Now they have slipped out of reality and exist only in the cognitive function we call memory, which contains merely the shadowy traces that are left in our cognitive worlds.

The future only exists as a myriad of potentialities and possibilities, as ideas which we can form within the cognitive function we call imagination. These ideas are not real, no matter how accurate our statistical probabilities may be. Events are not real until they happen as part of a present moment. 

In other words, we remember the past, we imagine the future, we only know the present. Only the present is real.

What does physics say to this normal way of thinking?

 

The Illusion of Time

Albert Einstein once wrote to a friend, “The past, present and future are only illusions, even if stubborn ones.” Einstein's theory of relativity denies any absolute, universal significance even to the present moment.

As we have seen, the pace of time has been speeding up and our location relative to the cosmos affects the pace of time. There is no “present moment” shared by every single thing and being in the cosmos.  We do not simultaneously share the same now. According to special relativity, such simultaneity is relative (to where we are, and when). 

Physicists have used various word pictures and examples to describe past, present, and future. I will include three that I have come across.

For the first, let’s imagine someone on earth asking a question like, “what is happening on Mars right now?”

Considering that Earth and Mars are about 20 light-minutes apart from each other, and that information cannot travel faster than light, an Earth-based observer is unable to know the situation on Mars at the same instant, and vice versa. We would have to infer the answer after the events have happened, after information has had a chance to travel back and forth, perhaps several times. 

This example demonstrates the impossibility of a “now” that two subjects might be able to know simultaneously. But this does not necessarily mean that “now” itself does not exist. 

Does it? 

The second illustration is more to the point of whether the present moment in fact exists, and by extension then, what is the nature of past and future as well.

Imagine that we decide to film ourselves as we drop an egg to the floor. The film will show the egg leaving our hand, falling through the air, landing on the floor, and shattering.

We can run the film backward or forward or freeze it at various points. Let’s also say that for this example we used physical film, not a phone. We can cut the film up into frames which we can shuffle randomly. 

It would be easy to rearrange the frames into an ordered sequence. To recreate the flow of the event, we arrange the frames with the intact egg first, and the broken egg at the end of the sequence.

We can also reverse the order of the frames and have the broken egg at the beginning and the intact egg at the end. 

Here is the point:

What we call time is the way we experience the flow of different events, from the egg in the hand to, say, the egg 11.3 inches from the floor to the exact moment of impact. Exact moment of impact? That is where things get tricky. 

In theory there is an “exact moment of impact,” but it is so infinitesimally small as to be beyond the ability of any human faculty (or instrument) to measure or grasp. Meaning, we cannot know it.

I am not saying, then, that the present moment does not exist. But it exists at a speed, which we can never know. We cannot freeze the frame at exactly the moment of “now.” In that way we can never be in the present, we are constantly in the process of change, but never in the now in between.

This brings me to the third example. Some physicists use the word “time-scape.” Think of it the way we do a landscape, in which we can see things near and far, and, if we turn around, we see what is behind us as well. In a landscape everything is “there”, even if at a given moment or from a given angle, we don’t look at it or see it.

The idea of “time-scape” means that all past and future events are located there together. What determines whether an event is past or present or future is our experience of it, from our reference point as the one experiencing it. 

So, imagine a landscape with an oak tree. The oak tree is there, but I only say “there it is” when I have the line of sight to be able to see it. 

With time-scape think of the events of the past and present and future like the oak trees. They are there in the “scape” all the time. However, my experience of them changes. For some physicists, the past and present and future are “there” in the time-scape all the time.

This raises lots of questions about determinism and whether everything is already laid out and these are philosophical questions we will come back to in the future. 

But for now, simultaneity, or “now” is relative. Time is the experience of things changing. Past, present and future are all in the same “scape.” Let me try to offer some tentative conclusions from combining all this, these three ways of seeing.

I see the tree, it is there, seemingly right now. But I am seeing it slightly later than the moment that the tree “experiences” as now because it takes time for light signals to go back and forth between an observer and an object. Of course that happens very, very rapidly. Light travels thousands of miles within a fraction of a second. 

However, if we had the ability to capture such fractions of time into frames (like the falling egg) we could break down the present moment from the perspective of each subject in a frame. In this case, from the perspective of myself and of the oak tree. It would be something like this:

From my center of experience my present moment is already in the oak tree’s past.

From the frame of reference for the oak tree, the oak tree’s present moment is still in my future. But it is there.

The past, and the future are both “present,” in each case relative to the subject experiencing a present moment.

 

My Way of Summarizing the Physics of Time

There is no actual “now,” not in an absolute sense, not in a way we can actually pinpoint or measure. For any measurement requires the capture of what is moving, not literally, but moving in the sense of this exchange that is really the meeting point of the oak tree’s future and my past. Which is neither of our “present.” What is real is the experience of time passing away, which is in fact our experience of the process of change.

At a personal level, I have spent a lot of time trying to be “present in the moment”, to live in the present. This is something many of us have been encouraged to do, I think. And I thought it was good advice, and I have tried really hard in times of meditation to do this, to be present in the moment.

I tried to explore that attempt in a song I wrote, called “Spaces.” I am currently getting it ready for release, but here is a draft or demo version.

 

Spaces

I see a dead moon rising, red sun going down, 

Bones of the mountains lay around me, I hear voices but they do not make a sound

 

Trying to live between the spaces of my was and my will be

Hoping behind my empty faces is a fullness of life I cannot see

 

All my persons and my personas, forged and fading works of art

Gliding past me in a mirror, that’s outside yet deep inside my heart

 

Trying to live between the spaces of my was and my will be

Hoping behind my empty faces is a fullness of life I cannot see

 

I’m clinging to the wreckage of the sunken vessel of my life

I feel the grip of fingers slipping, a voice says “just let go and slide”

 

Into the space between the spaces, of my was and my will be

And the Face behind the faces, of a fullness of life that lives in me

In reality, all my attempts to experience the present have just evaporated. It is just never there in my experience. And now I think physics is helping me understand why.

If time is our way of experiencing change, if time is a by-product of the process of change, then time is something more akin to heat or cold, which are both byproducts of other processes, but which we experience in certain ways. Time is more like that than it is like a “thing” that actually exists. 

Therefore, my attempts to be in the present moment, as for example in the song, will remain a chase for an elusive impossibility. What I can be “present” with is the experience of change, however. And that is more my focus now in meditation, and a habit I seek to cultivate through my day.

My reflections on this begin to take me beyond physics into philosophy, but I want to conclude the Episode by offering my initial thoughts about the implications of the physics of time for the cognitive functions of memory and imagination.

Memory is a way that the process of change continues in our experience of it. The present experience of a moment or an event or a thing may not be able to be frozen and held in our awareness, however it continues within the cognitive faculty we call memory. It is in this sense just as real as the “original experience” of that thing, of that process of change between its present and our future and our present and its past. It can be experienced repeatedly, and it all still exists to the memory, to the one remembering, indeed, “in” the one remembering. It is as real as when it happened, and both are experiential, and dare I say it, subjective, in that they both exist in the experience of the subjects experiencing them.

As I put it in another song, “memory’s just another way of seeing all the things that we’re still being.”

And what about the future? Is imagination the mirror image of the memory? Is it indeed perhaps the same faculty but applied to a different portion of the “time-scape”, to bring back a concept from earlier? 

I can hear a question or objection here.

“But, Kevin, our imaginations are just pictures we make of imaginary events and conversations, they are fiction even if we load them with statistical probabilities. The fact that some things turn out exactly or nearly as we imagined does not mean our imaginations were experiencing anything ‘real’ before it happened.”

My emerging way of understanding this is honestly still, well, emerging. 

My way of understanding is rooted in ways I think about consciousness, and what it means to be a subject, and what my own understanding of whether there is a big “S” Subject means for all of this. If one of the subjects is a Subject outside of the world physics is describing, and if we are entangled with other subjects including that Subject, then memory and imagination and knowing might be much more complex and mysterious than the already quite complex and mysterious cognition that we experience, we who are small “s” subjects.

This Episode has brought up new questions for me about that experience, and in doing so, I think back to the poem I shared earlier and my experiences of that doorway and hallway, and the questions I asked then. I can summarize my new questions this way: 

“Were we actually in the same moment when I saw her pass? Was the moment truly gone when she had passed? And if not, was I in fact alone?”

But now I have really stepped through the door from the physics of time into the philosophy of time and consciousness as well, and of entanglement. I need to bring myself back! One step at a time.

In the next Episode I will begin to dig into the philosophy of time, including the ways that some religious heritages have seen it. Consciousness and entanglement will need to wait a bit longer.

Until next time…