Tai Chi that Isn't Tai Chi but Is Tai Chi
by Christopher Dow
The first episode of the BBC documentary, Edge of the Universe, is about the search for extraterrestrial planets. Even the closest stars that contain planetary systems are so far from Earth that it is impossible to spot their planets directly. Not only are the planets of other solar systems too small to see, even for the most powerful telescopes, such objects are lost in the glare of their home suns.
But those suns hold the key to spotting their planets. Astronomers knew that if gas giants are orbiting a star, their gravitational pulls on their sun would cause the star to appear to wobble back and forth. Our gas giants—Jupiter and Saturn, primarily—do that to our sun, it’s just that it takes decades of observation to detect even the slightest relative movement due to the extreme lengths of these planets’ orbital periods. Eventually, though, astronomers began to spot such stars and, from the periodicity of their wobbles, could determine the approximate number, sizes, orbital distances, and orbital speeds of the gas giant or large terrestrial-type planets involved. The Kepler spacecraft, a space observatory launched in 2009, could detect much smaller planets, and to date, nearly 4,000 exoplanets have been found by Kepler and other means, with thousands of candidates waiting in the wings for confirmation. Nearly 700 of those already confirmed are Earth-size. Recently, astronomers announced the discovery of an astounding seven terrestrial-type planets in a single system: Trappist-1.
The Tai Chi point in all of this is the wobbling dance of a star and its planets. The wobbles of stars with multiple planets, such as our sun, can be quite complex, but not so with the first exoplanet ever confirmed, which is a huge gas giant orbiting alone and quite close to and quite rapidly around the star 51 Pegasi. The BBC program had a nice animation of the interaction between the two bodies, and it is almost exactly like the movement embodied in the Trammel of Archimedes, discussed above. In a very real sense, a single planet in such a situation doesn’t just orbit the star; the planet and the star each orbit around a fixed point located along the direct line of gravitational force between the two objects. This fixed point is located, of course, much closer to the star than to the planet, despite this particular planet’s considerable bulk and nearness to 51 Pegasi.
In essence, this is very similar to the interactive “dance” of a Tai Chi exponent dealing with incoming energy, even if that energy isn’t as neatly regular as forces acting on a planet constantly revolving in a nearly fixed orbit around a star. As an opponent launches the energy of an attack, which can come from a variety of angles and at different speeds, the exponent sinks, turns, and then performs one of the various actions that can follow to best deal with the incoming energy. In the case of a solar system like 51 Pegasi, both bodies might actually constantly rotate around one another, but the dynamics, from a Tai Chi perspective, are a little different.
From this perspective, the sun, having a stronger gravitational pull (chi) constantly rotates away from the mutual centerline gravitational pull (line of attack) between it and the planet (opponent), and the planet is flung to the side. But of course, the chi plus rotational ability of the Tai Chi exponent does not include the powerfully and mutually attractive force of gravity that exists between celestial bodies and which is constant and intractable, so the sun cannot actually fling away a planet that is in a stable orbit. But it flings it precisely enough to perfectly counteract the pull of gravity. This is what keeps the weaker-gravity planet in its orbit instead of falling inward. But the fact that the Tai Chi exponent isn’t bounded or limited by gravity in the same way allows the exponent to deal in diverse ways with energy that is not in a neat orbital pattern by applying other actions in addition to flinging, such as striking, pushing, pulling, bouncing away, and so forth.
The Trammel of Archimedes. Click on the image to see animation.
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