Broca's Brain - Carl Sagan [70]
On page 307 we find Isaiah making an accurate prediction of the time of the return of Mars for another collision with Earth “based on experience during previous perturbations.” If so, Isaiah must have been able to solve the full three-body problem with electrical and magnetic forces thrown in, and it is a pity that this knowledge was not also passed down to us in the Old Testament.
On pages 366 and 367 we find an argument that Venus, Mars and Earth, in their interactions, must have exchanged atmospheres. If massive quantities of terrestrial molecular oxygen (20 percent of our atmosphere) were transferred to Mars and Venus 3,500 years ago, they should be there still in massive amounts. The time scale for turnover of O2 in the Earth’s atmosphere is 2,000 years, and that is by a biological process. In the absence of abundant biological respiration, any O2 on Mars and Venus 3,500 years ago should still be there. Yet we know quite definitely from spectroscopy that O2 is at best a tiny constituent of the already extremely thin Martian atmosphere (and is likewise scarce on Venus). Mariner 10 found evidence of oxygen in the atmosphere of Venus—but tiny quantities of atomic oxygen in the upper atmosphere, not massive quantities of molecular oxygen in the lower atmosphere.
The dearth of O2 on Venus also renders untenable Velikovsky’s belief in petroleum fires in the lower Venus atmosphere—neither the fuel nor the oxidant is present in appreciable amounts. These fires, Velikovsky believed, would produce water, which would be photodissociated, yielding O. Thus Velikovsky requires significant deep atmospheric O2 to account for upper atmospheric O. In fact, the O found is understood very well in terms of the photochemical breakdown of the principal atmospheric constituent, CO2, into CO and O. These distinctions seem to have been lost on some of Velikovsky’s supporters, who seized on the Mariner 10 findings as a vindication of Worlds in Collision.
Since there is negligible oxygen and water vapor in the Martian atmosphere, Velikovsky argues, some other constituent of the Martian atmosphere must be derived from the Earth. The argument, unfortunately, is a non sequitur. Velikovsky opts for argon and neon, despite the fact that these are quite rare constituents of the Earth’s atmosphere. The first published argument for argon and neon as major constituents of the Martian atmosphere was made by Harrison Brown in the 1940s. More than trace quantities of neon are now excluded; about one percent argon was found by Viking. But even if large quantities of argon had been found on Mars, it would have provided no evidence for a Velikovskian atmospheric exchange—because the most abundant form of argon, 40Ar, is produced by the radioactive decay of potassium 40, which is expected in the crust of Mars.
A much more serious problem for Velikovsky is the relative absence of N2 (molecular nitrogen) from the Martian atmosphere. The gas is relatively unreactive, does not freeze out at Martian temperatures and cannot rapidly escape from the Martian exosphere. It is the major constituent of the Earth’s atmosphere but comprises only one percent of the Martian atmosphere. If such an exchange of gases occurred, where is all the N2 on Mars? These tests of the assumed gas exchange between Mars and the Earth, which Velikovsky advocates, are poorly thought out in his writings; and the tests contradict his thesis.
Worlds in Collision is an attempt to validate Biblical and other folklore as history, if not theology. I have tried to approach the book with no prejudgments. I find the mythological concordances fascinating, and worth further investigation, but they are probably explicable on diffusionist or other grounds. The scientific part of the text, despite all the claims of “proofs,” runs into at least ten very grave difficulties.
Of the ten tests of Velikovsky