Kevin's Watch

The night sky is a time machine. Look out and you look back in time. But this "time travel by eyesight" is not just the province of astronomy. It's as close as the machine on which you are reading these words. Your present exists at the mercy of many overlapping pasts. So where, then, is "now"?

As almost everyone knows, when you stare into the depths of space you are also looking back in time. Catch a glimpse of a relatively nearby star and you see it as it existed when, perhaps, Lincoln was president (if it's 150 light-years away). Stars near the edge of our own galaxy are only seen as they appeared when the last ice age was in full bloom (30,000 light-years away). And those giant pinwheel assemblies of stars called galaxies are glimpsed, as they existed millions, hundreds of millions or even billions of years in the past.

We never see the sky as it is, but only as it was.

Stranger still, the sky we see at any moment defines not a single past but multiple overlapping pasts of different depths. The star's image from 100 years ago and the galaxy image from 100 million years ago reach us at the same time. All of those "thens" define the same "now" for us.


The multiple, foliated pasts comprising our present would be weird enough if it was just a matter of astronomy. But the simple truth is that every aspect of our personal "now" is a layered impression of a world already lost to the past.

To understand how this works, consider the simple fact, discussed in last week's post, that all we know about the world comes to us via signals: light waves, sound waves and electrical impulses running along our nerves. These signals move at a finite speed. It always takes some finite amount of time for the signal to travel from the world to your body's sensors (and on to your brain).

A distant galaxy, a distant mountain peak, the not very distant light fixture on the ceiling and even the intimacy of a loved one's face all live in the past. Those overlapping pasts are times that you — in your "now" — are no longer a part of.

Signal travel time constitutes a delay and all those overlapping delays constitute an essential separation. The inner world of your experience is, in a temporal sense, cut off from the outer world you inhabit.

Let's take a few examples. Light travels faster than any other entity in the physical universe, propagating with the tremendous velocity of c = 300,000,000 m/s. From high school physics you know that the time it takes a light signal moving at c to cross some distance D is simply t = D/c.

When you look at the mountain peak 30 kilometers away you see it not as it exists now but as it existed a 1/10,000 of a second ago. The light fixture three meters above your head is seen not as it exists now but as it was a hundred millionth of a second ago. Gazing into your partner's eyes, you see her (or him) not for who they are but for who they were 10-10 of a second in the past. Yes, these numbers are small. Their implication, however, is vast.

We live, each of us, trapped in our own now.

The simple conclusions described above derive, in their way, from relativity theory and they seem to spell the death knell for a philosophical stance called Presentism. According to Presentism only the present moment has ontological validity. In other words: only the present truly exists; only the present is real.

Presentism holds an intuitive sway for many people. It just feels right. For myself, when I try and explore the texture of my own experience, I can't help but feel a sense of the present's dominance. Buddhism, with its emphasis on contemplative introspection, has developed a sophisticated presentist stance concerning the nature of reality. "Anyone who has ever mediated for anytime" the abbot of a Zen monastery once told me "finds that the past and future are illusions."

Yes, but ...

The reality that even light travels at a finite speed forces us to confront the strange fact that, at best, the present exists at the fractured center of many overlapping pasts.

So where, then, are we in time? Where is our "now" and how does it live in the midst of a universe comprised of so many "thens"?

Fist and Faith wrote:An interesting idea, the overlapping pasts. But the present. the now, is the moment when I experience all of these overlapping pasts.

Vraith wrote:Left out of the article is another interesting tidbit: For the light itself with which I see my love's eyes and the most distant star, exactly the same amount of time passes; none at all.

There was once a man who looked at a tree through a window. His mind wandered into thought. He saw the tree outside but he knew that the experience of perceiving that tree was created in his mind. If the perception existed in the mind then where was what he was looking at... was it outside or in his head? Perhaps it was in the glass. So he was looking at a tree outside, but the experience of seeing was created in his mind... if the sight was a part of him, was the tree him? But what about the tree that existed outside... were there two trees now? This is gibberish, thought the man, snapping out of his semi trance.


The following day the man bumped into a mathematician entering a church and they began a conversation about evolution. The first life on this planet had been simple, following basic reactionary processes. Slowly, over many many generations the organisms had increased in complexity as they adapted or died. Eventually what we might call consciousness had emerged. But what, asked the mathematician, was the difference between reaction and consciousness? Well, the man replied, surely it is the capacity to experience. What is experience but a complex reaction? The man was not sure he fully understood the question... instead of replying he added more requirements: thought, he said, and self awareness... these are more than reaction. And what of atoms? asked the mathematician. What? At this point the man ended his conversation.


That night the man had a dream. He dreamed of the creation of the universe. Out of the initial chaos particles began to form, and soon the universe came to light as photons came into being. There were no atoms yet, indeed it was an age before hydrogen began to form... but the man's dream-time was accelerating and soon stars were bursting to life, clusters of stars, spirals with many billions of them... and in the heart of the stars different atoms were taking shape... slowly one of the galaxies began to expand to soak up all of his awareness... it began to shift and distort. And then it was no longer a galaxy but it had become a tree, and from the end of the branches of that tree grew a fruit, and the fruit was people. One of the fruit-people opened their mouth and out of it came a clockwork model of a solar system. But it did not last long as the dream consciousness was moving again, it flowed towards the fruit-person and into their eyes, through their eyes into a tunnel. The tunnel went on for what seemed like forever until finally and suddenly, as if passing a threshold, it shattered into the big bang of creation. And now there was a rhythm, a drumbeat... steady and grounding... but soon it was no longer a drumbeat, it took on a shrill edge and shifted towards the high pitched periodic buzz of a bedside alarm.


A few days later the man went to see a psychologist at the circus. He recounted his experiences. Perhaps you are picking up psychic signals, the psychologist jibed. The psychologist's words had an effect on the man's mind. As a result of this effect, a certain pattern of neuron interaction ensued, which in turn resulted in an electrical signal being sent to some of the man's muscles, which proceeded to contract in an intricate pattern, which caused waves of vibration in the air, which travelled into the psychologist's ears, where they transferred the vibration into particularly tiny bones which in turn stimulated an electrical signal to be sent to the psychologist's brain, where there was a pattern of neural activity, and it was interpreted and experienced as a sound, but more than a sound for other area's of his brain and knowledge further decoded the sound to discover that there was a complex code in the vibrations that formed words, concepts, meaning. There's no such thing as telepathy, heard the psychologist.


Next day, the man met a neuroscientist at Stonehenge. They talked for some time about various things, and afterwards the man decided to remain to think some more. The brain is physical. Conciousness arises from the brain. It is somehow in the brain. Likely the mind, experience, is a field... some kind of standing wave... so I'm a standing wave? Or am I my body? Is there more than one me? Who is asking this question, and to who? Just then an alien spaceship descended from the heavens and he was abducted.


In their spaceship the aliens began dissecting his body and strange visions ran through his mind. first there was a brain and beside it a mirror, slowly the two began to get closer and closer together... he noticed that as this happened the brain seemed to be increasing in size and it became apparent to him by some intuition that it was developing and becoming more complex.... after what seemed like an eternity the brain and the mirror came into contact. Suddenly white turned to black and black to white and the brain and the mirror were no longer a brain and a mirror but was instead a camera pointing at a television set, and on that television was the chaotic formation of intricate patterns characterised by a video feedback loop. And the patterns said: Am I the camera or the screen?


There was once a man who looked at a tree through a window. He had forgotten that consciousness was in the light all along.

Fist and Faith wrote:There is. It's just that, as he says, the present (my experience of events) doesn't match up with the moment of those events. But I experience it as though it did. As the saying goes, if you can't tell the difference, what difference does it make?

SerScot wrote:F&F,

Fist and Faith wrote:There is. It's just that, as he says, the present (my experience of events) doesn't match up with the moment of those events. But I experience it as though it did. As the saying goes, if you can't tell the difference, what difference does it make?

Just out of curiosity how long does this "present moment" last?

aliantha wrote:This is all very cool stuff. But one can take it too far.

I used to know a guy who argued that he couldn't be held accountable for stuff he did in the past because it was, y'know, past, and "I'm not that person any more". Not as in, "I've changed for the better," but as in, "That was that moment and this is this moment." Jerk.

(He had numerous strategies for dodging responsibility -- this was just one of them. )

Cambo wrote:

SerScot wrote:F&F,

Fist and Faith wrote:There is. It's just that, as he says, the present (my experience of events) doesn't match up with the moment of those events. But I experience it as though it did. As the saying goes, if you can't tell the difference, what difference does it make?

Just out of curiosity how long does this "present moment" last?

Eternity.

C.S. Lewis wrote:In a word, the Future is, of all things the least like eternity. It is the most completely temporal part of time-- for the Past is frozen and no longer flows, and the Present is all lit up with eternal rays.

Vraith wrote:

aliantha wrote:This is all very cool stuff. But one can take it too far.

I used to know a guy who argued that he couldn't be held accountable for stuff he did in the past because it was, y'know, past, and "I'm not that person any more". Not as in, "I've changed for the better," but as in, "That was that moment and this is this moment." Jerk.

(He had numerous strategies for dodging responsibility -- this was just one of them. )

Hmmm...But what if it was literally true? As those cases [usually caused by head trauma] where the person really is a "different person?"

Murrin wrote:By which part of our consciousness do we define "now"? How accurate is it possible to define it? All that we experience from external stimuli has taken time to reach our awareness - and even the electrochemical signals within and between the parts of our brain cannot be instantaneous. Each part of our mind can never be aware of what other parts are thinking at the exact same moment*.


*A "moment" in this usage being an instantaneous period of time - the limit tending to zero of delta-tau.

Fist and Faith wrote:

Murrin wrote:By which part of our consciousness do we define "now"? How accurate is it possible to define it? All that we experience from external stimuli has taken time to reach our awareness - and even the electrochemical signals within and between the parts of our brain cannot be instantaneous. Each part of our mind can never be aware of what other parts are thinking at the exact same moment*.


*A "moment" in this usage being an instantaneous period of time - the limit tending to zero of delta-tau.

All true. "Now" is when we think it is. When we perceive; when we experience. Not when the event actually took place.

And if we didn't understand Now, we wouldn't have ever come up with the concept of time. We wouldn't have ideas of the past, or even the word "past". And we wouldn't be able to differentiate our memories from the present, or even our memories from each other.