What’s up with gravity? Not much, it turns out

I haven’t always paid close attention to gravity. It’s kind of a mundane subject. Gravity just always seems to be hanging around, and I take it for granted.  How does it do that anyway? You’d think it would fall. What is kind of surprising to me is how long it took for scientists to discover gravity. I mean, Isaac Newton didn’t discover gravity until the late 1600s. Why did people think things fell down for the few thousand years before that? 

In fact, if you didn’t know about gravity, why would one even expect things to fall down? Why couldn’t an apple just fall up? Or sideways? Why did we decide to call the direction an apple falls “down” anyway? Is falling down worse than falling up? “Help, I’ve fallen up and I can’t get down.”

I admit that down is significant, if for no other reason than that is where we fall. The act of falling can actually be quite invigorating if one doesn’t think too much about the act of stopping the fall. I suppose even stopping falling is a scientifically fascinating concept in itself. The technical term, I believe, is “ouch.” 

Newton actually did get his ideas from an apple, although, apparently, the apple didn’t hit him on the head. He told many people that he was out wandering through a garden when he saw an apple fall. It apparently just struck him one day — the idea, not the apple — that something had to be pulling the apple towards the earth. 

It has always made me wonder a little about Newton. I mean, didn’t he have a job to do or something? Who has time to wander in gardens? Was he actually watching apples fall, or did he just sort of see it happen out of the corner of his eye? Anyway, there are two great lessons to be learned from his experience besides the fact that Newton was a strange fellow. 

First, this story demonstrates the value of wandering around outdoors in gardens instead of going to school. If he’d been in class he would never have discovered anything. It also shows how science is first and foremost a matter of asking strange questions.

It’s not as if people hadn’t already had rich experiences with gravity from just walking around, tripping, swinging from vines in the trees and falling out of bed. There were plenty of observations, I suppose. What was needed was for someone to ask, “Why do things all fall in the same direction?” His answer was to declare that there must be some sort of invisible force that acted over distance to attract things to it. At the time, some people accused him of dabbling in the occult. I mean, really? An invisible force? You have to admit it sounds suspicious. 

His real contribution, though, was to ask, “How high does gravity go?” Newton decided it had to go quite a ways into the air because the apple tree was pretty tall. This led him to speculate that perhaps this invisible force extended all the way to the moon! Even he was surprised to calculate that it apparently went all the way to “infinity and beyond,” to quote Buzz Lightyear. In fact, his theory and calculations more or less settled the question of how and why the moon circles the earth and the planets circle the sun. 

Anyway, Newton did not receive any compensation for his most famous slogan: “A body at rest tends to remain at rest unless an external force is applied to it.” That is only one of his three wise sayings. Knowing this makes you now one-third as smart as Isaac Newton. 

Unfortunately he never explained how to avoid those external forces. I am working on that problem by spending as much time as possible remaining at rest in the garden. You might say that gravity has kind of got me down.

Gary McCallister, .(JavaScript must be enabled to view this email address), is a professor of biology at Colorado Mesa University.


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