This Part 1. To read Part 2 go to:
Navigating The Finite, Time is This Rubbery Thing Part 2
A recent issue of the New Yorker had an interesting article on David Eagleman and how we experience time. Fortunately the entire article is a freebie on the New Yorker’s web site.
Navigating The Finite, Time is This Rubbery Thing Part 2
A recent issue of the New Yorker had an interesting article on David Eagleman and how we experience time. Fortunately the entire article is a freebie on the New Yorker’s web site.
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| Eagleman In His Lab |
Eagleman is a rather fascinating fellow who got the inspiration for his life’s work from a near fatal fall when he was a teenager. He fell from the roof of a home under construction that he was snooping about. During the fall he experienced a dilation of time. The time duration of his fall seemed much longer than normal and he grew up with a fascination for how our brains experience time. He is now a neuroscientist who studies among other things how the brain experiences time. It turns out that according to Eagleman “Time is this rubbery thing.” He poses an interesting experiment. Stand before a mirror, look at your left eye, then at your right eye, back and forth…left, right, left, right. Eagleman claims that we experience seeing each eye as an instantaneous event. But this can’t be true because there is the transit time for your eyes to move and focus. I tried the experiment and I thought to myself, “Eagleman is full of shit, it happens instantaneously.” Then it occurred to me “Oh, that’s his point.” We experience it as an instantaneous event, but it is not. Where did the missing moments go? Eagleman claims that our brains filter out the time lapse. I question that though, does our brain filter out the moments of real time or can we move our eyes and focus faster than our visual system can process the image. Eagleman knows a lot more about the brain than I do, so I’ll venture that it is brain filtering.
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| Click for full size. This is sort of what I see with my eyes. |
I have my own experiment for you. Tonight after it is dark, go in your kitchen and turn off the lights. Look at the LED digital clock on your stove or microwave from a normal distance. If you look at it, it appears to be a solid number, you don’t experience any sense of flashing. Now (again with the lights off and from a normal distance from the clock, say 5 to 10 feet) move your eyes slowly to the left side of the room. Now rapidly swing your eyes to the far right as fast as you can. For an instant you should be able to see a track of numbers with dark spots in between. If you don’t, it is probably because your appliances are newer than mine and have better clocks. I don’t know what new appliances will do. What is happening when you rapidly swing your eyes is that the flashing display leaves a track of lit numerals on your moving retina when the LED is on and a dark gap when it is off. Your retina, being a squishy electro-chemical biological contraption, does not operate immediately, it retains what is called an afterimage. Think of your eyes reaction to a photo flash. So in this experiment, your retina becomes a moving piece of film responding to the ons and offs of the flashing display in slightly different locations on its surface. The afterimage allows you to discern the flashing for a brief moment before it fades. This is why the room has to be dark. You can also have some fun (if you are a weirdo like me) by setting a variable speed fan between you and the display. Try looking at the display through the moving fan blades. Try the different speeds and try turning the fan off and on while watching the display through the blades. As the speed of the moving blades gets in synch with the flash rate of the display, the display will appear to behave oddly, flashing at variable rates.
This is the same principle as a strobe tachometer. The tach works by flashing a strobe light at a rotating shaft with a line scribed on it. You shine the strobe at the shaft and adjust the rate of the strobe until you see the line on the shaft stops moving. CAUTION! DO NOT TOUCH THE SHAFT—IT IS STILL ROTATING. A little of my old technical writing coming back to life, it is amazing how strong the temptation is to touch the shaft. You can still hear the noise of the motor, feel the wind blowing in your face but it appears that the shaft has stopped moving. It looks dead still. You get this weird sense of fascinated disbelief and you WANT to touch the shaft. Our sense of vision is so strong, and our desire to touch is so innate, that touching the shaft is almost irresistible. The smart guy inside your head has to stop you: “Hey dumb ass don’t touch the shaft.” Looking at the end of the shaft like the face of the clock works the best. If you see only one stationary line then you are flashing the strobe at either the same speed that the shaft is rotating or some exact fraction of the speed. To make sure it is not a fraction of the speed, increase the rate of flashing and look for multiple lines. If you double the rate of the flashing so that your tach is twice the speed of the shaft, you will see two lines 180 degrees out.
Here is another interesting observation garnered from playing with strobe tachometers. The tach clicks every time it fires the strobe. It does not take a very high speed for the flashing strobe to appear constantly on, you can no longer discern the flashes somewhere around 30 flashes per second (it has been a long time since I have played with a strobe tachometer). Yet you can still discern the individual clicks. It is actually a bit disconcerting if you think about it. The strobe light appears to be constantly on, yet the rate of clicking is relatively low. The thing has to be really flying before the clicks turn into a continuous buzz, and even then the buzz has a on/off quality while the flashing just appears to be constantly on. So it turns out that our hearing is far quicker than our vision. It responds faster and it can discern events at a faster rate than vision. The article mentions that pistol shots are used to start foot races instead of a flashing light, because we respond faster to sound.
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| A fast vertical swing. |
So what is the point of my microwave oven clock and strobe tachometer discussion? Simply this, our brains present to us what we believe is a plausible story of the world about us that appears to be rock solid in continuity. Quite simply you can look at the clock in your microwave and know what time it is, the clock has a continuous display. But it and most of the rest of what we experience is a fairy tale that our brains put together for us so that we can make sense of the world. The display in your microwave (if it is ancient like mine) is not constantly on. A good bit of the time it is off, and that is what those dark gaps are that you see when you rapidly swing your eyes. My guess is that if the contraption that makes the display flash had an audible click, you would have no problems discerning the off period between each click. My prediction is that it would be a rapid clicking…click…click…click…click rather than buzzzzzzzzzzzz. So what do those dark gaps represent? It is, in a left handed sort of way, a visual representation of our brain’s image processing time, made available to us by the after image properties of our retina. Think about it. For a brief instant you are viewing your brain’s inability to see reality. And the irony of it is, you are using the very same properties, the processing time of nerve cells, to view it. If our retinas were instantaneous, you would not see a track of numerals with dark gaps. To weirdos like me, that is a totally cool concept.
Returning to the article, Eagleman has an interesting experimental problem. He wants to know does time dilate for those involved in a fatal fall? Naturally finding volunteers for this experiment is difficult. Oddly enough, they won’t even respond to huge payments of money. Even more difficult is to conduct a post experimental interview with the subject of the experiment. There is just something about a fatal fall that puts a real damper on casual chat. Apparently the amusement park industry has a solution. There is some ride down in Texas where a contraption takes you 110 feet in the air and suddenly drops your body into a free fall that thankfully ends face up in a net. It is about as close to a fatal fall as you can get without the fatality. Post experiment interviews are much more informative.
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| The Scad |
So here is Eagleman’s experiment. Somehow he convinces people to go on this ride. I don’t know how he does that, I can assure you that he would never convince me to do that, and I like experiments. Part of my resistance to this experiment would be the fear of soiling my pants, and a certain question irresistibly pops into my mind….What do they do to the net when somebody does soil their pants? Surely we don’t get own individual nets, and surely people must soil themselves quite frequently on this ride. They drop you so that you land on your back. Bear with me, I can’t help myself here. Imagine you have your new spiffy shorts on and it is a wonderful day at the park. You are strolling along past a ride called the Scad. A geek with a clipboard comes up and says. I’ll give you $100 to strap this chronometer on your wrist, take that ride, and tell me what you see. Sounds simple enough. You get on the ride, up you go and suddenly, your body is in a free fall....You dutifully look at your chronometer and at mid drop “OH NO…I am shitting my self.” You impact the net at 50 mph face up.
Squuuiiisssshhhiiittttt!!!!!!!!
This experiment is not for me. Anyhow they strap a LED display on the subjects wrist. The LED display is set so that it changes numbers, but the rate of change is slightly faster than what our brains can normally perceive. The subject is supposed to observe the display while they take the ride. If time truly dilates during the fall, the subject should be able to read the numbers on the display. The results, alas disappointing, no one can read the display. Time does not dilate! But what is interesting is that after the victim….ahhh…rider settles down, their time estimate of how long the ride lasted is always about 36% longer than actual. So while time did not actually dilate, the subject’s perception of time did. So what is more real, reality or your perception of it? Well we all know that time ticks at a standard rate. Perhaps, but try convincing yourself of that fact the next time you are getting a tooth drilled at the dentist. It is strange to think that we live in a world where the ticks of time are the same length regardless if we having a tooth drilled or having sex. Sure don’t seem that way.
So how do our brains perceive time? According to the article:
“studies suggested a hodgepodge of systems, each devoted to a different time scale—the cerebral equivalent of a sundial, an hourglass, and an atomic clock.
“Mother Nature’s a tinkerer instead of an engineer,” Eagleman says. “She doesn’t just invent something and check it off the list. Everything is layers on layers built on top of each other, and that provides tremendous robustness.” Parkinson’s disease can impair our ability to time intervals of a few seconds, for instance, but leave split-second timing intact.Just how many clocks we contain still isn’t clear. The most recent neuroscience papers make the brain sound like a Victorian attic, full of odd, vaguely labelled objects ticking away in every corner. The circadian clock, which tracks the cycle of day and night, lurks in the suprachiasmatic nucleus, in the hypothalamus. The cerebellum, which governs muscle movements, may control timing on the order of a few seconds or minutes. The basal ganglia and various parts of the cortex have all been nominated as timekeepers, though there’s some disagreement on the details. The standard model, proposed by the late Columbia psychologist John Gibbon in the nineteen-seventies, holds that the brain has “pacemaker” neurons that release steady pulses of neurotransmitters. More recently, at Duke, the neuroscientist Warren Meck has suggested that timing is governed by groups of neurons that oscillate at different frequencies. At U.C.L.A., Dean Buonomano believes that areas throughout the brain function as clocks, their tissue ticking with neural networks that change in predictable patterns. “Imagine a skyscraper at night,” he told me. “Some people on the top floor work till midnight, while some on the lower floors may go to bed early. If you studied the patterns long enough, you could tell the time just by looking at which lights are on.”
Time isn’t like the other senses, Eagleman says. Sight, smell, touch, taste, and hearing are relatively easy to isolate in the brain. They have discrete functions that rarely overlap: it’s hard to describe the taste of a sound, the color of a smell, or the scent of a feeling. (Unless, of course, you have synesthesia—another of Eagleman’s obsessions.) But a sense of time is threaded through everything we perceive. It’s there in the length of a song, the persistence of a scent, the flash of a light bulb. “There’s always an impulse toward phrenology in neuroscience—toward saying, ‘Here is the spot where it’s happening,’ ” Eagleman told me. “But the interesting thing about time is that there is no spot. It’s a distributed property. It’s metasensory; it rides on top of all the others.” “
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| Brain Structures, Amygdala |
I love the analogies, “Mother Nature’s a tinkerer instead of an engineer,” “brain sound like a Victorian attic” and “impulse toward phrenology in neuroscience”. So with all these layers of distributed time keepers ticking away in our brains, why do we experience a dilation in our perception of time during one of these falls? What is happening? According to the article when we are in mortal danger, a part of a brain called the amygdala is activated. The amygdala is responsible for emotions and memory. When in danger it records the events with exacting detail, and it is this packing of your memory with these exact details that seems to slow down your perception.
A month before I turned 13, I was down in the woods on a snowy day. My sister and a friend and I were going to make a camp fire along the cliffs at the creek. This is just below the rocky outcrop, I called Mount Olympus. I had to go back home for some forgotten supply. So I left my friend and sister and went back home. Additional kids had showed up in my absence, so I decided to surprise them all by appearing overhead on the cliff. So I circled back around and had to descend the very steep hill side below Mount Olympus but above the cliff.
It was snowing. It was a very steep hillside with various springs and seeps that turn to ice. Remember that smart guy inside your head that I said that keeps you from touching the shaft? He hadn’t quite developed a robust voice yet. So he is screaming “Hey dumb ass, stay off the hillside.” But another voice, let’s call him shithead, was telling me how cool it would be scare the kids from on top of the cliff. Yep I scared them! I scared the hell out them when I slipped on the ice and fell about 20 feet right into the middle of them. Fortunately I didn’t land on any them. All I can remember is someone saying “Here comes Sextant”. Then a sharp pain and blackness. I have no idea how long I was knocked out. My sister said it was maybe 5 to10 minutes. She was only 8 at the time. Most of the kids scattered while I was out. My friend and sister helped me walk home. I really wasn’t injured other than probably a mild concussion but I was really upset and frightened. Well when I got home my mother decided I was OK but wouldn’t let me sleep in case I had a concussion. Oddly the only thing in the world I wanted to do then was sleep. That is all I can remember of it now, is this terrible, terrible desire to sleep and not being allowed. Try as I may, I can’t remember any sense of time dilation. It happened really quick, but I can still hear that kid saying “Here comes Sextant.”
About five years ago, my wife and I were Geocaching on a steep rocky hillside in Venango County. My wife took a step and she did this long pirouette and then down she went and hit her head on a large rock. I can remember this as if it happened yesterday. She slipped and then seemed to spin for long minutes and while she is spinning my arms are flailing at her trying to grab her but I keep missing. In those slow motion moments of hyper-reality, I can see all these huge rocks and I can see her hitting them before she actually does and this just seemed to go on and on. Then she goes down in slow motion and I can see the rock that she is going to hit and the certainty slams into me that she is going to die and it just takes goddamn forever. She hits the rock with the back of her head and her eyes shut and I just know that I have lost her and I am babbling something stupid like “Oh no! Oh no!” It seems to take forever for me to reach her. She then opens her eyes, shakes her head, stands up and says something to the effect that “wow that hurt.” She is OK! Thank God.
I don’t know how many revolutions she made, probably no more than one, but it seemed like 35, and I kept flailing at her trying to grab her, and I can see these rocks and it is like I am considering each one--will that be the one that kills her as she goes rotating on to the next. The whole thing couldn’t have taken more than a couple of seconds, but in my memory I can just see her spinning and me flailing at her and these rocks which almost seemed to have motion in themselves and this just went on and on like a bad dream. So what is my dilation of this event? It sure as hell seems longer than 36%. How long is a small forever? I can’t even begin to say how long it took, but my intellect tells me of course that it was fast. My memory of it is oddly jumbled and yet exact. I can see the hemlocks and the rocks spinning around, but I wasn’t spinning, she was. This was a very painful thing to witness, and the memory of it has become magnified in my mind, she is spinning, I am flailing, and the world seems to be spinning around me. I can’t believe that she was not seriously injured. Actually she wasn’t completely OK, she hurt her neck and it has bothered ever since. But at the time, watching her fall I was sure she was going to die. So my perception of time indeed dilated, and the memory of this event has become so surreal over time that it is no longer accurate. I shudder and give thanks to God that I did not lose her that day.
End of Part 1.
To read Part 2 go to:
Navigating The Finite, Time is This Rubbery Thing Part 2
End of Part 1.
To read Part 2 go to:
Navigating The Finite, Time is This Rubbery Thing Part 2
Image Credits:
Eagleman in his Lab The New Yorker, April 25, 2011, The Possibilian by Burkhard Bilger
Digital Clocks, me.
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