Busted! Planet-Making Theories Dont Fit Extrasolar Planets
Famed planet-hunter Geoff Marcy is giving theorists headaches. The leading theories of planet formation won’t stand up to observations of hundreds of planets we know. In National Geographic News reporter Richard Lovett lamented, “The more new planets we find, the less we seem to know about how planetary systems are born, according to a leading planet hunter.” We cannot apply theories that fit our solar system to other systems: “In theory, other stars with planets should have gotten similar starts. But according to Marcy, theory has implications not born out in reality.”
Specifically, planetary orbits should be circular, but many extrasolar planets have elliptical orbits. Everything should orbit in the same plane and direction, but many have highly inclined or even retrograde orbits; “Orbital inclinations are all over the map,” Marcy said. And Neptune-sized planets should be rare, since models of our water giants require highly unusual starting conditions; there are too many out there, Marcy noted; “Theory has struck out,” he told the American Astronomical Society last month.
His critics complained that modeling is complicated and difficult. Hal Levison said that simplifying them leads to “crappy models.” Marcy thought that without taking into account planetary interactions, future discoveries, as they multiply, “will give the theoreticians yet more reasons to tear out their hair.” For more on Geoff Marcy, see 02/02/2011.
Maier’s Law says, “If the facts do not conform to the theory, they must be disposed of.” (see corollaries, right sidebar). A science that cannot fit observations to theory does not win the honor of being called a science. It may be a job, a profession, an avocation, a hobby; but to be a science, there should be some concordance between theory and observations. Has planetary cosmogony done any better than alchemy yet? Let them play but come back later when they have something. One theory they never consider is the top-down theory; that planets were created with stars, but have been fragmenting and interacting since then. This theory has the advantage of fitting the observations of providential fine-tuning for our own Privileged Planet.