Imagine Another Wet, Rocky Planet
Apr 24, 2009

A recent ESO (European Southern Observatory) press release announced that the “lightest exoplanet” ever discovered is orbiting a nearby red dwarf star. The planet has less than twice the mass of the Earth, and its “year” is about three days long. It is, “very likely, a rocky planet.”

Another planet in the same system orbits within the star’s “habitable zone” and “could even be covered by a large and deep ocean.”

Or not.

Let’s back away from the philosophical chasm over which these speculations are suspended and check what’s anchoring the cantilevered assumptions that support them. What astronomers observed were variations in the spectrum of the light from the star. The rocks and oceans and habitable zones extend from assumptions about how gravity organizes matter. Gravity extends from assumptions about mass. Mass, it turns out, is simply not anchored.

Astronomy is founded on a sensory bias: we see motion. With a few comparison tools—a ruler and a clock—we can measure position and distance and can directly calculate velocity and acceleration. Sight is our only “astronomical” sense. All others are “local,” terrestrial: for example, we sense force with muscles and measure it with hands-on comparison tools such as springs and balances. Hence, the physics of early astronomy—of Ptolemy, Copernicus, and Kepler—was kinematics, motion without muscle.

Newton connected motion and force with a mathematical relationship and therewith introduced dynamics. But the muscle—and measurement of forces—was still confined to the Earth. So talk of forces in space was derived from theory and assumptions: quantities were calculated, not measured comparatively. This method was so successful at predicting the visual measurements of importance in past centuries that the difference between calculated values and directly compared measurements was forgotten. The difference is one of assumptions.

The big assumption that got away was the matter of mass: specifically, that matter and mass were equivalent and therefore interchangeable concepts. Matter, like force, is a thing that we sense “on location”—something that we bump into. Mass, on the other hand, is a term of proportionality in an equation that relates measurements of muscle sensations to measurements of eye sensations—of force to distance or motion.

In mathematical form, m = F/a. Matter is physical and sensible; mass is abstract and non-sensible. The confusion of the two fools us into thinking that Newton’s equations explain matter.

Since force is only measured on the Earth, the determinations of mass and of other quantities that involve mass, such as the gravitational constant, G, are necessarily geocentric. When astronomers calculate forces in space, they crunch geocentric numbers. On Earth, physicists can compare measurements of force with measurements of motion in the same setting to calculate the ratio—mass. In space, astronomers must calculate forces from measurements of motion and the assumption that mass works the same as on Earth.

Even on Earth, mass doesn’t work the same from one experiment to the next. “The two most accurate measurements [of G] have experimental errors of 1 part in 10,000, yet their values differ by 10 times that amount. So physicists are left with no idea of its absolute value.” [“Earth’s Magnetic Field ‘Boosts Gravity’,” New Scientist, 22 September 2002.]

If we transpose variables in the equation for gravitational force to collect measured quantities on one side and derived ones on the other, we have Fr^2 = GMm. That the measurements differ means that GMm varies while the (experimentally controlled) quantity of matter remains unchanged. When applied to astronomical bodies, it means that calculations of mass tell us nothing about the matter associated with the mass.

Within the solar system, what’s expected for the mass of planets based on other assumptions about qualities of matter (chemical composition, density, etc.) is surprised by observations: Saturn seems to be missing a lot—its calculated density is less than water; Mercury seems to have a surplus—the excess is disguised in a bloated iron core; comets are made out to be fluff—despite looking like rocks.

Outside the solar system, what’s expected isn’t even close to what’s observed. White dwarf stars and neutron stars appear to have so much more mass than matter can encompass that new forms of “collapsed matter” have been invented to save the theory. Galaxies, in turn, appear so anorexic in their outer parts and so obese at their cores that occult forms of “dark matter” and “black holes” have been conjured.

Modern astronomy has abandoned the physical and sensible world for an abstract universe of non-sense. It has become noted more for its sensational press releases than for its critical evaluations of results. Who can doubt that fame and fortune are directly attracted to hype? That’s politics and religion, not science.

What’s needed is a better understanding—any understanding—of the anchor for cantilevering assumptions. What’s the physical basis for the abstraction we call mass? Why does matter respond to force with different motions? What’s this thing we call gravity that lies unexplained and uninvestigated behind a merely descriptive equation?

One clue is our (again geocentric) predilection to think of matter as solids, liquids, and gases. Our space-age forays away from the Earth have given us ample evidence to realize that matter is plasma, which usually has far-reaching electrical effects. The Electric Universe is one pioneering investigation of how knowledge of plasma can modify Newtonian dynamics to provide a sensible, and therefore testable, theory of mass. It in turn leads to a more accurate and coherent—and “space-centric”—understanding of astronomical matters.

Mel Acheson