Sunday, February 22, 2015

When Reason Outruns Imagination

Think about the word "imagination." How does it make you feel? What images does it call to mind? If you're like me, it's full of positive associations. I think of artists and inventors, bright colors, and imagined adventures. When I do an image search for "imagination," I see that it evokes the same images for others. The word "imagination" seems to capture the imagination.

Now think of the word "reason" or "reasoning." That one isn't dressed in such glowing colors, is it? It's a colder, more serious concept. It evokes images of numbers, logic, machines with gears, and maybe Rodin's The Thinker. When I do the image search for "reasoning", I see once again that others think of the same kind of things. It's not nearly the feel-good word that "imagination" is. The difference corresponds to the pop psychology notion of the logical left brain and creative right brain, as exemplified in this Mercedes Benz ad:

Click for credits. From
People tend to think of imagination and reason as somehow opposed, and many of them fall firmly on the side of imagination. I think that's the wrong way to look at it. First, imagination and reason are partners, not opponents. The two are inextricably linked, and the best breakthroughs in reasoning require leaps of the imagination. Second, reason sometimes outruns imagination. Oddly enough, reason tells us the world is more fantastic than we can clearly imagine.

I realized this the other day after reading a famous quote by John Playfair, a Scottish mathematician and scientist. Playfair was a frequent companion of the pioneering geologist James Hutton on Hutton's geologic excursions, and he wrote a book that popularized Hutton's ideas. One day in 1788, Playfair and Hutton took a boat trip to a place on the Scottish coast known as Siccar Point. At this spot, as the picture shows, near-horizontal layers of rock sit on top of other layers that are nearly vertical. It's a geologic feature known as an angular unconformity. Honestly, it doesn't look like much. It's certainly not going to become an internet meme, like the Mercedes ad did. But they truly do represent something incredible. To see it, you have to understand the story they tell. And that requires imagination as well as reason.

Photo by Dave Souza. Click for credits. 
Hutton did the reasoning long ago, so try to imagine--really imagine--what Hutton told Playfair. He explained that vertical rock layers you see on the right were originally horizontal, because they formed from sediments at the bottom of an ancient sea. Since then, they have been turned to stone, and then lifted and tilted sideways as part of the formation of an ancient mountain range. It was just as solid and long-lasting as the mountain ranges we see today, but now it's long gone. The mountains began to erode as soon as the rose, just as mountains are doing today. After ages and ages, they were eroded down to a flat surface--the top surface of the vertical rocks. Then they were covered by a new sea, which deposited a layer of horizontal sediments on the older surface of the vertical ones. Then those sediments turned to stone, and were lifted up above the water and began to erode, finally exposing some of the rocks they were built upon.

The more you think about how much time all this would have required, the more you realize awe-inspiring it is. As Playfair would later recall: "The mind seemed to grow giddy by looking so far into the abyss of time." That's the famous part of his quote, and it gets repeated all the time in discussions of deep geologic time. What he said next is less poetic, but perhaps just as profound: "and while we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much farther reason may sometimes go than imagination can venture to follow."

Hutton's explanation of Siccar Point was perfectly reasonable, but hard to imagine. It's hard to even believe. In fact, many people to this day--over 40% in the United States--refuse to believe the Earth could be that old. But Hutton's ideas have stood the test of time. Reason has shown us a world more vast than our imaginations can capture.

That's not the only time it's happened, either. Look up some winter night at Betelgeuse, the red star that defines one of Orion's shoulders. Science, evidence, and reason tell us that Betelgeuse is unbelievably huge--billions of sun-sized stars could fit inside it. It's even more unbelievably far away--roughly 635 light years, which means the light we now see from it has been traveling toward us since the late Middle Ages. Of course, light is no slowpoke--it can cross the United States many times in the blink of an eye. Light goes that fast, and takes it hundreds of years to make the journey from Betelgeuse to Earth. Once again, reason has gone further than my imagination can venture to follow. And that's just the beginning. That same beam of light would take over 100,000 years to cross our galaxy, which is just one of billions of galaxies in the universe.

Of course, it's not just the scale of the universe that surpasses our imagination. Its sheer weirdness is also enough to short circuit our brains. Einstein used cold, hard, mathematical reason to show that space and time are bound up together into a unified, four-dimensional spacetime, and that gravity is a curvature in spacetime. Can you visualize something curving in four dimensions? I can't, and I bet you can't either, but spacetime goes ahead and curves anyway. We know it does, because we can look through a telescope and see it. A few days ago, NASA released a Hubble image of what looked like a smiley face in deep space. Its eyes are two galaxies (each containing more stars than you could count in a lifetime), while the apparent rings that define the face are the distorted images of even more distant galaxies. The gravitational field of the galaxies in the middle is curving spacetime and thus bending the light from the more distant galaxies, the same way a fisheye lens distorts what we see through it. We're looking through a fisheye lens hundreds of thousands of light years across, made of spacetime itself.

Why do we know this is true? And how were we able to put a telescope in space that can spot these things? Because of reason. AND because of imagination. Both are necessary. Einstein had to do some intense formal reasoning to come up with his theory of relativity, but he also had to have a vivid imagination. He often imagined riding on a beam of light, trying to visualize how the universe would look from such a vantage point. Similarly, Hutton needed reasoning to figure out the history and implications of Siccar Point, but he also needed to imagine ancient mountains and oceans. He needed to contemplate expanses of time that most people would dismiss as preposterous. For the Hubble telescope to become a reality, somebody first had to imagine launching a telescope into space. And then a whole lot of people had do a lot of very precise mathematical reasoning to actually put that telescope there. Now it captures images that capture imaginations around the world. Reason and imagination are partners, and they can do far more together than apart.

So, while imagination is a wonderful thing, we should also give reason its due. Imagination alone can take us to fantastic worlds that exist only in the mind. That's great, as long was we don't confuse them with the real world. But reason combined with imagination can tell us how fantastic the real world can be. It's told us again and again that the universe is far more vast and strange than we ever could guessed based on imagination alone. It's even told us things about the universe that we haven't found ways to imagine. So, perhaps we should celebrate reason as much as imagination, and stop thinking of it as boring and colorless. Reason is imagination's partner in showing us what a big, fabulous world we really live in.

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