April 20, 2018
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Trapped in the fourth dimension

Contributed | BDN
Contributed | BDN
By Dana Wilde, BDN Staff

We’re all trapped in the fourth dimension.
As far as we can tell, we are carried in it with no detours from one moment to the next, today into tomorrow, this year into next, summer to winter, birth to death. It devours birds, beasts and flowers, gnaws iron, buried ancient Troy, grinds down stones and mountains. And apparently we’re stuck at one spot in it: the present. Time has us pinned to now, like canoeists with no paddles — we can’t go back downstream and can’t drive ahead. Neither the past nor the future exists; there is only the now and here.
Except that this experience of time as a flow on one point appears to be an illusion of some kind. The theory of relativity indicates — and experiments with atomic clocks support — that time is not a flow at all, but a dimension with plottable points, like in space. In fact, space and time are not two things interacting with each other, but one, which the physicists call space-time. It is pretty widely accepted in modern science that, despite our experience of it, the past and future are as real as the present.
Here’s one of the ways this riddle gets worked out. Since time, like space, is a dimension, it has locations. For example, 4 p.m. is a location in time the way Troy, Maine, is a location in space. Now, when I’m in 4 p.m. Tuesday, I’m not in 2 p.m. Tuesday — or any other day, for that matter. So to me, 2 p.m. Tuesday does not exist; nor does 6 p.m., because I’m not there yet. This is how we experience it and think about it, anyway.
But here’s the catch: 4 p.m. is a location in time the way Troy is a location in space. When I’m in Troy, I’m not in Bangor, the same way when I’m in 4 p.m. I’m not in 2 p.m. But Bangor is still there, it’s just out of sight. If Bangor still exists when I’m in Troy, why can’t 2 p.m. still exist when I’m in 4 p.m.?
The scientific answer is: It does.
Past, present and future, according to the physicists, exist all together simultaneously as the dimension of time. Physicists call this “block time,” a phrase parallel to the philosophical term “eternity.” It refers to the idea that all time and space exist at once — space-time. In other words, it’s likely that 2 p.m. Tuesday does still exist, you just can’t get there from here, as you can get from Troy to Bangor.
Why we are stuck in the present, no one knows. Einstein, who was quite bothered by this part of the riddle, suggested that we separate past, present and future in our minds to keep life orderly. If everything was happening to us at once, we couldn’t handle it. Humankind cannot bear very much reality. That doesn’t explain anything, though. It just observes a psychological benefit of our experience of time.
The physics of time got a lot weirder after Einstein. Quantum physicists’ mathematical calculations of the behavior of subatomic particles indicated that not only do distinctions between past, present and future not correspond to the way the physical world works, but distinctions between what did and didn’t happen, or what will and won’t happen, are also questionable. The “many worlds” interpretation of quantum physics indicates that it’s entirely possible that everything that can happen, happens, happened and will happen. We, for some unknown reason see only one happening at a time, out of an infinite number of happenings.
This is not science fiction. It is, however, so far outside our earthly experience that it’s hard to see how block time would ever become an everyday frame of mind. I don’t say it’s impossible. It’s just very difficult to imagine. And that will be the next part of the discussion: imaginary time.



Read more on the nature of time:

“Time, it’s even stranger than you think”

“Imaginary time”

“Time travel: What’s holding us back?”

Amateur Naturalist archive


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