When my love swears that she is made of truth,
I do believe her, though I know she lies.
Shakespeare, Sonnet 138
My sister was in second grade — two years older and far wiser than me. We were watching the clouds scuttling past the chimney when she announced, “Look! You can see the Earth move.” We argued for awhile — she learned that in school, but what can you expect from a brother in kindergarten? No way the earth moves — if it did, I would know it.
As a matter of fact:
- Earth spins on its axis at 1,000 miles per hour (1,600 km/hr) .
- It orbits the sun at 67,000 mph (107,000 km/hr).
- Our Solar System rotates around the center of the Milky Way at 514,000 mph (828,000 km/hr).
- The Milky Way zips through space at 1.3 million mph (2.1 million km/hr).
- And the Universe? Well, that’s more complicated:
“The expansion rate of the universe is called the Hubble parameter. Because the fabric of the universe is being stretched out as it expands, galaxies farther away from us appear to be moving away faster. This is why the Hubble parameter is measured in units of kilometers per second per megaparsec (km/s/Mpc).
“We don’t know the rate exactly, but in the last 50 years, we’ve narrowed it down to either 67 or 73 km/s/Mpc. That’s not to say we believe the true expansion rate lies between those two values, but rather we think it’s reasonably close to either one or the other. So a galaxy 1 Mpc away — 3.26 million light-years — is moving away from us at 73 km/s (or 67 km/s, depending on which scientists you’re talking to). A galaxy 10 Mpc away would be moving at 730 (or 670) km/s.”
That’s an incomprehensible number of incomprehensibly big things moving at incomprehensible speeds across incomprehensible distances. And somewhere in the midst of them, there’s the Earth — moving, big time. But thanks to gravity, proprioception (awareness of where we are in space), and peripersonal neural networks (awareness of what’s around us), we’re firmly rooted right here, unaware of it all, keeping our bearings by things that don’t move.
Or so we think. As a matter of fact:
- A day isn’t 24 hours. Actually, it’s more complicated than that: “Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to the stars.” Plus it’s slowing down, and it also wobbles as it spins, so that its axis has shifted 34 feet in the past 120 years.
- Plus the North Magnetic Pole isn’t the same as the North Pole, and it’s moving, so the compass needle you’re relying on to guide you through the woods is always shooting at a moving target — something I experienced hiking in the Rockies, where the iron in the rocks keeps North always on the move.
- The same is true for the North Star — its position relative to Earth is moving in small increments, but over time they add up:
“In Homer’s time, that star, which today we call Polaris, stood a dozen degrees from the North Pole; in Columbus’s time, it stood three and a half degrees away; in Sputnik’s time, it stood right near the pole. But about AD 15,000, as Earth keeps wobbling like a top, Polaris will sit forty-five degrees away.”
In other words:
True North is not always True, and not always North.
Things we think are fixed and stable, often aren’t. Our perceptions go unchallenged because for purposes of managing our experience, good enough is good enough. My five-year-old self didn’t need to know about all that spinning, orbiting, expanding, and wobbling in order to run out and play. The same is true for my current self. sitting here typing this sentence: I may be deceived in my present conviction that the Earth under this building is not moving, but I can still sit here and type no matter what the truth is.
In fact, self-deception is sometimes useful for life and death issues:
“Evidence suggests that specific instances of self-deception can enhance wellbeing and even prolong life. For example, multiple studies have found that optimistic individuals have better survival rates when diagnosed with cancer and other chronic illnesses, whereas ‘realistic acceptance’ of one’s prognosis has been linked to decreased life expectancy.”
On the other hand, there are times when we’d like to not be deceived — like the one Shakespeare wrote about.
More to come re: self-deception and why belief doesn’t have to be true in order to work.
 “How fast is the universe expanding? How do astronomers calculate the expansion rate?” Astronomy Magazine (July 26, 2018). (After several tries, I couldn’t get a link to the article to work, but if you copy and past it into a Google search, the article will come up.)
 “Proprioception is the medical term that describes the ability to sense the orientation of your body in your environment. It allows you to move quickly and freely without having to consciously think about where you are in space or in your environment. Proprioception is a constant feedback loop within your nervous system, telling your brain what position you are in and what forces are acting upon your body at any given point in time.” Very Well Health.
 “Peripersonal neurons are cells in the brain that monitor the space around the body. Their activity rises like a Geiger counter to indicate the location of objects entering a margin of safety. The neurons can detect an intruding object through vision, hearing, touch, and even by the memory of where objects are positioned in the dark.” The Spaces Between Us: A Story of Neuroscience, Evolution, and Human Nature. by Princeton psychology and neuroscience professor Michael S. A. Graziano.
 Accessory to War: The Unspoken Alliance Between Astrophysics and the Military, by Neil deGrasse Tyson.