These Backyard Naturalist columns, if you follow them, all seem to be about juncos, beetles, beech trees, how cold it is, other planets, how cold it is on other planets, etc., etc. But the truth is, like with the people who are always making long speeches in department meetings, what I’m talking about isn’t really what I’m talking about.

What I’m really trying to figure out is:

• Who are we?

• Where are we? (I stole the phrasing for these two questions from Thoreau.)

• How big is the universe?

• Why is time passing so fast? (Or really, why is it passing at all? Or even, is it actually passing?)

• Is there intelligent life on other planets? And if so, why haven’t I met any aliens?

• What are spiders thinking about?

• Will my son ever be the one who pays for lunch?

I have no scientific answers to any of these questions, mainly because I’m not a scientist. I do, however, have certain credentials as a philosopher, so I know how to rummage through a lot of different facts, figures and ideas and get them to come out on the leeward side of interesting, even if they’re far-fetched.

One idea that keeps floating in my direction looks (when viewed in a certain slant of light) like a clue to answers to the above questions, or at least some of them. I’m talking, obviously, about the weird ways in which we experience — and do not experience — dimensions.

We live in four dimensions. The three dimensions in space — length, width and height — most of us have a pretty good grip on. The fourth dimension we also experience intimately, but our grip on it is tenuous and even varies from person to person in ways that length, width and height do not. The fourth dimension, I mean, is time.

What is time, anyway? In the 17th century, Isaac Newton laid down the law about what time is in a very common sensical way. He said time is a flow. This seems to make sense because the word “flow” accurately describes our experience of it.

It turned out he was wrong, though. About 200 years later, Einstein showed that time is not a flow at all. It is a dimension integrated with length, width and height. The whole four-dimensional universe is called spacetime.

To understand how time is a dimension and not a flow, think of a location. If you and I want to meet somewhere, we name a point on a street (a length), which we travel to from another street to the left or right of it (a width), and then the floor of a building there (ground floor, second floor, third floor — a height). If I’m on the second floor and you’re on the ground floor, or we’re at different intersections, we miss each other. And there’s one more factor: time. If we don’t reach the same location in space at the same time, we miss each other.

This means — and a lot of physicists more or less agree on this, though they talk about it in different ways — that time is not made up of one flowing moment, but it is more or less a block, the way the length, width and height of space seem like a block. The past and future exist simultaneously with the present (the way Augusta and Bangor still exist along I-95 even when you’re in Waterville). Explaining how that could be is quite a problem for science, since the past and future are apparently not here to experiment on.

Length, width and height are spatial dimensions. Time is the temporal dimension because for some completely unknown reason, we experience it as a motion forward.

Now, here’s where it gets somewhat weird. It is widely thought among physicists that a fifth dimension actually exists. This is hard to visualize for us because we don’t experience it. But one reason the physicists are pretty sure it’s there is that many of their mathematical equations describing what happens in the world work out much better when they count in a fifth dimension. In fact, some physicists are pretty sure that 10 or 11 dimensions actually exist because most of the glitches in their math are solved when they calculate assuming those dimensions are real. Some physicists think there may be 26 dimensions.

If dimensions beyond length, width, height and time actually exist, why don’t we experience them? The commonest answer is: because they are extremely small and they are curled up, sort of like cylinders.

What this means, I don’t know.

And why do we experience time as a flow and not another iteration of space?

I have no idea. (I stole the phrasing for this from Annie Dillard.)

But it seems clear that while my son (who to me is still the little boy he used to be, and also the man he will be) and I share many wavelengths of thought, we do not always seem to be talking about what I think we are talking about. It’s like our thoughts are traveling back and forth from different dimensions and some are getting lost in translation. If I could unroll one more dimension, maybe we could locate each other every time we talk. Maybe. And who knows what you could learn about spiders.

Dana Wilde lives in Troy. His writings on the Maine woods are collected in “The Other End of the Driveway,” available from Backyard Naturalist appears the second and fourth Thursdays each month. You can contact him at [email protected].

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