Broca's Brain - Carl Sagan [61]
In Exodus, Chapter 9, it is said that the cattle of Egypt all died, but of the cattle of the Children of Israel there “died not one.” In the same chapter we find a plague that affects flax and barley but not wheat and rye. This fine-tuned host-parasite specificity is very strange for cometary vermin with no prior biological contact with Earth, but is readily explicable in terms of home-grown terrestrial vermin.
Then there is the curious fact that flies metabolize molecular oxygen. There is no molecular oxygen on Jupiter, nor can there be, because oxygen is thermodynamically unstable in an excess of hydrogen. Are we to imagine that the entire terminal electron transfer apparatus required for life to deal with molecular oxygen was adventitiously evolved on Jupiter by Jovian organisms hoping someday to be transported to Earth? This would be yet a bigger miracle than Velikovsky’s principal collisional thesis. Velikovsky makes (page 187) a lame aside on the “ability of many small insects … to live in an atmosphere devoid of oxygen,” which misses the point. The question is how an organism evolved on Jupiter could live in and metabolize an atmosphere rich in oxygen.
Next there is the problem of fly ablation. Small flies have just the same mass and dimensions as small meteors, which are burned up at an altitude of about 100 kilometers when they enter the Earth’s atmosphere on cometary trajectories. Ablation accounts for the visibility of such meteors. Not only would cometary vermin be transformed rapidly into fried flies on entrance into the Earth’s atmosphere; they would, as cometary meteors are today, be vaporized into atoms and never “swarm” over Egypt to the consternation of the Pharaoh. Likewise, the temperatures attendant to ejection of the comet from Jupiter, referred to above, would fry Velikovsky’s flies. Impossible to begin with, doubly fried and atomized, cometary flies do not well survive critical scrutiny.
Finally, there is a curious reference to intelligent extraterrestrial life in Worlds in Collision. On page 364 Velikovsky argues that the near-collisions of Mars with Earth and Venus “make it highly improbable that any higher forms of life, if they previously existed there, survived on Mars.” But when we examine the Mars as seen by Mariner 9 and Viking 1 and 2, we find that something over one-third of the planet has a modified cratered terrain somewhat reminiscent of the Moon and displays no sign of spectacular catastrophes other than ancient impacts. The other half to two-thirds of the planet shows almost no sign whatever of such impacts, but instead displays dramatic evidence of major tectonic activity, lava flows and vulcanism about a billion years ago. The small but detectable amount of impact cratering in this terrain shows that it was made much longer than several thousand years ago. There is no way to reconcile this picture with a view of a planet recently so devastated by impact catastrophism that all intelligent life would thereby have been eliminated. It is also by no means clear why, if all life on Mars were to be exterminated in such encounters, all life on Earth was not similarly exterminated.
PROBLEM VI
MANNA
MANNA, according to the etymology in Exodus, derives from the Hebrew words man-hu, which means “What is it?” Indeed, an excellent question! The idea of food falling from comets is not absolutely straightforward. Optical spectroscopy of comet tails, even before Worlds in Collision was published (1950), showed the presence of simple fragments of hydrocarbons, but no aldehydes—the building blocks of carbohydrates—were known then. They may nevertheless be present in comets. However, from the passage of Comet Kohoutek near the Earth, it is now known that comets contain large quantities of simple