Pendulum swings . . . a nerdy post

 

I am fascinated by pendulums, particularly the Foucault pendulums that can be seen in the towering halls of museums and chambers throughout the world.  (I tried to make one for a science project last century). A cable is suspended from a fixed point several stories above with a heavy weighted metal bob attached to the end close to the floor.  If undisturbed the bob hangs perfectly still above its perfect point of equilibrium, that place where the natural force of gravity holds it in place.  But it seems impossible to let the pendulum rest in its perfect place. It is just hanging there, doing nothing. Who wants to watch that?  Inevitably the bob is displaced several yards or meters,  pulled back like a swing at the park to get going, and then released.  This is what folks like me, hanging over the second floor railing, want to see. The pendulum slowly swings, back and forth, back and forth, passing its point of equilibrium in the center at its greatest speed.  It continues to swing, back and forth, constantly pulled by the force of gravity toward its point of equilibrium.  But the momentum of the weighty bob defiantly carries it past that point. It swings to the opposite side until the pull of gravity matches its momentum, where it seems to pause for a moment, then swing back in the direction from which it came, flying past the point of equilibrium and back to where it started, pausing, and starting the whole thing over again.  This goes on for a long, long time, much longer than I have to stand and watch. It is all as a result of that original displacement from the natural point of equilibrium.

There is another twist to a Foucault pendulum.  If the cable is long enough (that's why they are located outside or in multi-story halls), it is possible to observe another movement of the bob. The path of its back and forth course changes slowly.  For example, at some point, if the pendulum continues to swing, its path will become perpendicular to its original path, and then slowly move back to its original path.  The change in the path is due to the rotation of the earth.  Cool, huh?

When watching a pendulum it is easy to believe that the natural state of the structure is the movement of the bob, back and forth, back and forth, and that if it ever stops swinging it must be displaced again, to resume its familiar movement. It is easy to believe that the bob will find equilibrium only if it swings back and forth, from one side to the other, until it finds its proper place.  But the truth is, the back and forth is a result  of a disruption of the natural state of the pendulum, of being at rest in its point of equilibrium. The back and forth is merely visual evidence of the power of gravity and the fixed point, constantly pulling the bob back to its proper place, never letting the bob fully escape its grip.

I like it when the pendulum is displaced and I can watch it swing..

But in this world of humanity the pendulum seems to be swinging from extreme to extreme wildly. As it is moved by this displacement it is then subject to other pulls of this world that change its path.  The point of equilibrium is only a blur as we go screaming by at break-neck speed.  We pull against the other, displacing our world from its perfect place, as if we can win the contest with brute force, as if the bob will come to rest not at the point of equilibrium, but at the unlikely point at the extreme to which we, in our own interest, have pulled it.

But we can't.

When we exert power over another in any way, it is only temporary. The pendulum will swing. And, unfortunately, it will not stop at the point of equilibrium. The power of the other will pull it to the other extreme.  And so on and so on.

And the truth is just a passing blur.

Until we stop pulling against each other.

You go first . . .


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