I wrote my 750 words again! (Answers to even-numbered exercises are in the back of the book.)
The blinking light on the side of your laptop computer actually represents the average heartbeat of every human on Earth who is within one mile of a monitoring node.
Which is approximately 45% of the population of the planet.
Most of the time it is rock-steady, as any excitement in one heart, or in one group of hearts, is exactly balanced through the vast mushy laws of large numbers, by the ebbing of excitement in the same number of hearts elsewhere.
But on some days, if you are watching the blinking light as I often do, you will notice it slowly subtly down, or speeding suddenly up, as somewhere there is a large anomaly, a sudden gasping, a thrill, an excitement, in the entire population of a small city in Rawanda, or every Girl Scout in the USA; or somewhere else an entire continent goes to bed, and on the other side of the world, due to an international holiday, their usual counterbalancers are sleeping in.
Because, vast and sprawling and numerous though we are, humanity is still finite. There are only so many left-handed people, only so many people about to open a soda can, only so many Lutherans. The number of religious sects is large, but smaller than the number of grains of sand on the beach, which is smaller than the number of atoms in one grain of sand, which is smaller than the number of possible Sudoku grids, which is itself still finite, and so smaller than nearly all of the positive integers.
Looking down Platform 29, across all those people waiting patiently, or impatiently, for the 6:45 to arrive, and thinking that each of them has a history, and a set of beliefs, a complicated web of preferences and fears, we are already far beyond the vastness that any one of us can comprehend (one, two, three, seven, many), but if all of those people were to vanish suddenly, spirited off by aliens or vaporized by more mundane means, the size of the world as a whole would be reduced by only an imperceptible fraction.
So your laptop’s light blinks, almost always, at the same steady pace, as all of our hearts (or the hearts of all of us within one mile of a monitoring node), average out into a signal with just one bit of content (“still the same, still the same, still the same”); all the complexity nicely smoothing out, a hill here balanced by a valley there, a hundred orgasms in one set of college dorms nicely making up for a hundred hearts drifting off to sleep in another set one time zone away.
Take a breath. Feel yourself breathing, and what it feels like to breathe. Feel yourself thinking, and what it feels like to think. If you are worried, feel what it feels like to worry. Feel your own heartbeat slowing. Look at the reflection of the blinking light on the Ethernet connector, or the shiny tabletop, or your fingernail. As your heart slows down, imagine that you can see the light slowing down, by the smallest imaginable amount.
Imagine that you can feel, somewhere deep in your gut or your inner ear, the Earth turning under you, and the stars whirling around.
It the Earth turning, or the stars? We know, these days, that motion in a straight line is relative; that jogger is the one who is moving, and I on the park bench here with my peanuts am the one sitting still, only because the math is simpler that way; but either one might be true. It’s not so simple for rotation, though, for things spinning around. Ernst Mach thought, at least if we listen to Einstein (and we might as well, since we listened to him on that whole “motion in a straight line” thing), that the universe has a large-scale structure (large as large, larger than anything), that determines what counts as spinning and what doesn’t; but I hear down at the corner pub that this is not true in all solutions to the field equations.
Feel your breath, and what it is like to breathe. Feel your heart beating, and what it is like to have a heart, beating. Watch the blinking light, and feel your heart beating with all of the other hearts (the ones within a mile of a monitoring node). Feel the Earth turning under you, and the stars whirling around you (with or without closed timelike curves). Be still.