Broca's Brain: The Romance of Science
Page 13
Velikovsky’s account of the history of the Earth’s rotation is difficult to follow. On page 236 we have an account of the motion of the Sun in the sky which by accident conforms to the appearance and apparent motion of the Sun as seen from the surface of Mercury, but not from the surface of the Earth; and on page 385 we seem to have an aperture to a wholesale retreat by Velikovsky-for here he suggests that what happened was not any change in the angular velocity of rotation of the Earth, but rather a motion in the course of few hours of the angular momentum vector of the Earth from pointing approximately at right angles to the ecliptic plane as it does today to pointing in the direction of the Sun, like the planet Uranus. Quite apart from extremely grave problems in the physics of this suggestion, it is inconsistent with Velikovsky’s own argument, because earlier he has laid great weight on the fact that Eurasian and Near Eastern cultures reported prolonged day, while North American cultures reported prolonged night. In this variant there would be no explanation of the reports from Mexico. I think I see in this instance Velikovsky hedging on or forgetting his own strongest arguments from ancient writings. On page 386 we have a qualitative argument, not reproduced, claiming that the Earth could have been braked to a halt by a strong magnetic field. The field strength required is not mentioned but would clearly (cf. calculations in Appendix 4) have to be enormous. There is no sign in rock magnetization of terrestrial rocks ever having been subjected to such strong field strengths and, what is equally important, we have quite firm evidence from both Soviet and American spacecraft that the magnetic-field strength of Venus is negligibly small-far less than the Earth’s own surface field of 0.5 gauss, which would itself have been inadequate for Velikovsky’s purpose.
PROBLEM IV. TERRESTRIAL GEOLOGY AND LUNAR CRATERS
REASONABLY enough, Velikovsky believes that a near-collision of another planet with the Earth might have had dramatic consequences here-by gravitational tidal, electrical or magnetic influences (Velikovsky is not very clear on this). He believes (pages 96 and 97) “that in the days of the Exodus, when the world was shaken and rocked… all volcanoes vomited lava and all continents quaked.” (My emphasis.)
There seems little doubt that earthquakes would have accompanied such a near-collision. Apollo lunar seismometers have found that moonquakes are most common during lunar perigee, when the Earth is closest to the Moon, and there are at least some hints of earthquakes at the same time. But the claim that there were extensive lava flows and volcanism involving “all volcanoes” is quite another story. Volcanic lavas are easily dated, and what Velikovsky should produce is a histogram of the number of lava flows on Earth as a function of time. Such a histogram will, I believe, show that not all volcanoes were active between 1500 and 600 B.C., and that there is nothing particularly remarkable about the volcanism of that epoch.
Velikovsky believes (page 115) that reversals of the geomagnetic field are produced by cometary close approaches. Yet the record from rock magnetization is clear-such reversals occur about every million years, and not in the last few thousand, and they recur more or less like clockwork. Is there a clock in Jupiter that aims comets at the Earth every million years? The conventional view is that the Earth experiences a polarity reversal of the self-sustaining dynamo that produces the Earth’s magnetic field; it seems a much more likely explanation.
Velikovsky’s contention that mountain building occurred a few thousand years ago is belied by all the geological evidence, which puts those times at tens of millions of years ago and earlier. The idea that mammoths were deep-frozen by a rapid movement of the Earth’s geographical pole a few thousands of years ago can be tested-for example, by carbon-14 or aminoacid racemization dating. I should be very surprised if a very recent age results from such tests.
Velikovsky believes that the Moon, not immune to the catastrophes which befell the Earth, had similar tectonic events occur on its surface a few thousand years ago, and that many of its craters were formed then (see Part 2, Chapter 9). There are some problems with this idea as well: samples returned from the Moon in the Apollo missions show no rocks melted more recently than a few hundred million years ago.
Furthermore, if lunar craters were to have formed abundantly 2,700 or 3,500 years ago, there must have been a similar production at the same time of terrestrial craters larger than a kilometer across. Erosion on the Earth’s surface is inadequate to remove any crater of this size in 2,700 years. There are not large numbers of terrestrial craters of this size and age; indeed, there is not a single one. On these questions Velikovsky seems to have ignored the critical evidence. When the evidence is examined, it strongly counterindicates his hypothesis.
Velikovsky believes that the close passage of Venus or Mars to the Earth would have produced tides at least miles high (pages 70 and 71); in fact, if these planets were ever tens of thousands of kilometers away, as he seems to think, the tides, both of water and of the solid body of our planet, would be hundreds of miles high. This is easily calculated from the height of the present water and body lunar tide, since the tide height is proportional to the mass of the tide-producing object and inversely proportional to the cube of the distance. To the best of my knowledge, there is no geological evidence for a global inundation of all parts of the world at any time between the sixth and fifteenth centuries B.C. If such floods had occurred, even if they were brief, they should have left some clear trace in the geological record. And what of the archaeological and paleontological evidence? Where are the extensive faunal extinctions of the correct date as a result of such floods? And where is the evidence of extensive melting in these centuries, near where the tidal distortion is greatest?
PROBLEM V. CHEMISTRY AND BIOLOGY OF THE TERRESTRIAL PLANETS
VELIKOVSKY’S thesis has some peculiar biological and chemical consequences, which are compounded by some straightforward confusions on simple matters. He seems not to know (page 16) that oxygen is produced by green-plant photosynthesis on Earth. He makes no note of the fact that Jupiter is composed primarily of hydrogen and helium, while the atmosphere of Venus, which he supposes to have arisen inside of Jupiter, is composed almost entirely of carbon dioxide. These matters are central to his ideas and pose them very grave difficulties. Velikovsky holds that the manna that fell from the skies in the Sinai peninsula was of cometary origin and therefore that there are carbohydrates on both Jupiter and Venus. On the other hand, he quotes copious sources for fire and naphtha falling from the skies, which he interprets as celestial petroleum ignited in the Earth’s oxidizing atmosphere (pages 53 through 58). Because Velikovsky believes in the reality and identity of both sets of events, his book displays a sustained confusion of carbohydrates and hydrocarbons; and at some points he seems to imagine that the Israelites were eating motor oil rather than divine nutriment during their forty years’ wandering in the desert.
Reading the text is made still more difficult by the apparent conclusion (page 366) of Martian polar caps made of manna, which are described ambiguously as “probably in the nature of carbon.” Carbohydrates have a strong 3.5 micron infrared absorption feature, due to the stretching vibration of the carbon-hydrogen bond. No trace of this feature was observed in infrared spectra of the Martian polar caps taken by the Mariner 6 and 7 spacecraft in 1969. On the other hand, Mariner 6, 7 and 9 and Viking 1 and 2 have acquired abundant and persuasive evidence for frozen water and frozen carbon dioxide as the constituents of the polar caps.
Velikovsky’s insistence on a celestial origin of petroleum is difficult to understand. Some of his references, for example in Herodotus, provide perfectly natural descriptions of the combustion of petroleum upon seepage to the surface in Mesopotamia and Iran. As Velikovsky himself points out (pages 55-56), the fire-rain and naphtha stories derive from precisely those regions of the Earth that have natural petroleum deposits. There is, therefore, a straightforward terrestrial explanation of the stories in question. The amount of downward seepage of petroleum in 2,700 years would not be very great. The difficulty in ext
racting petroleum from the Earth, which is the cause of certain practical problems today, would be greatly ameliorated if Velikovsky’s hypothesis were true. It is also very difficult to understand on his hypothesis how it is, if oil fell from the skies in 1500 B.C., that petroleum deposits are intimately mixed with chemical and biological fossils of tens to hundreds of millions of years ago. But this circumstance is readily explicable if, as most geologists have concluded, petroleum arises from decaying vegetation, of the Carboniferous and other early geological epochs, and not from comets.
Even stranger are Velikovsky’s views on extraterrestrial life. He believes that much of the “Vermin,” and particularly the flies referred to in Exodus, really fell from his comet-although he hedges on the extraterrestrial origin of frogs while approvingly quoting from the Iranian text, the Bundahis (page 183), which seems to admit a rain of cosmic frogs. Let us consider flies only. Shall we expect houseflies or Drosophila melanogaster in forthcoming explorations of the clouds of Venus and Jupiter? He is quite explicit: “Venus-and therefore also Jupiter-is populated by vermin” (page 369). Will Velikovsky’s hypothesis fall if no flies are found?
The idea that, of all the organisms on Earth, flies alone are of extraterrestrial origin is curiously reminiscent of Martin Luther’s exasperated conclusion that, while the rest of life was created by God, the fly must have been created by the Devil because there is no conceivable practical use for it. But flies are perfectly respectable insects, closely related in anatomy, physiology and biochemistry to the other insecta. The possibility that 4.6 billion years of independent evolution on Jupiter-even if it were physically identical to the Earth-would produce a creature indistinguishable from other terrestrial organisms is to misread seriously the evolutionary process. Flies have the same enzymes, the same nucleic acids and even the same genetic code (which translates nucleic acid information into protein information) as do all the other organisms on Earth. There are too many intimate associations and identities between flies and other terrestrial organisms for them to have separate origins, as any serious investigation clearly shows.
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 nitriles-in particular, hydrogen cyanide and methyl cyanide. These are poisons, and it is not immediately obvious that comets are good to eat.
But let us put this objection aside, grant Velikovsky his hypothesis, and calculate the consequences. How much manna is required to feed the hundreds of thousands of Children of Israel for forty years (see Exodus, Chapter 16, Verse 35)?
In Exodus, Chapter 16, Verse 20, we find that the manna left overnight was infested by worms in the morning-an event possible with carbohydrates but extremely unlikely with hydrocarbons. Moses may have been a better chemist than Velikovsky. This event also shows that manna was not storable. It fell every day for forty years according to the Biblical account. We will assume that the quantity that fell every day was just sufficient to feed the Children of Israel, although Velikovsky assures us (page 138) from Midrashic sources that the quantity that fell was adequate for two thousand years rather than a mere forty. Let us assume that each Israelite ate on the order of a third of a kilogram of manna per day, somewhat less than a subsistence diet. Then each will eat 100 kilograms per year and 4,000 kilograms in forty years. Hundreds of thousands of Israelites, the number explicitly mentioned in Exodus, will then consume something over a million kilograms of manna during the forty years’ wandering in the desert. But we cannot imagine the debris from the cometary tail falling each day, [7] preferentially on the portion of the Wilderness of Sin in which the Israelites happened to have wandered. This would be no less miraculous than the Biblical account taken at face value. The area occupied by a few hundred thousand itinerant tribesmen, wandering under a common leadership, is, very roughly, several times 10−7 the area of the Earth. Therefore, during the forty years of wandering, all of the Earth must have accumulated several times 1018 grams of manna, or enough to cover the entire surface of the planet with manna to a depth of about an inch. If this indeed happened, it would certainly be a memorable event, and may even account for the gingerbread house in “Hansel and Gretel.”
Now, there is no reason for the manna to have fallen only on Earth. In forty years the tail of the comet, if restricted to the inner solar system, would have traversed some 1010 km. Making only a modest allowance for the ratio of the volume of the Earth to the volume of the tail, we find that the mass of manna distributed to the inner solar system by this event is larger than 1028 grams. This is not only more massive by many orders of magnitude than the most massive
comet known; it is already more massive than the planet Venus. But comets cannot be composed only of manna. (Indeed, no manna at all has been detected so far in comets.) Comets are known to be composed primarily of ices, and a conservative estimate of the ratio of the mass of the comet to the mass of the manna is much larger than 103. Therefore, the mass of the comet must be much larger than 1031 grams. This is the mass of Jupiter. If we were to accept Velikovsky’s Midrashic source above, we would deduce that the comet had a mass comparable to that of the Sun. Interplanetary space in the inner solar system should even today be filled with manna. I leave it to the reader to make his own judgment on the validity of Velikovsky’s hypothesis in the light of such calculations.
PROBLEM VII. THE CLOUDS OF VENUS
VELIKOVSKY’S prognostication that the clouds of Venus were made of hydrocarbons or carbohydrates has many times been hailed as an example of a successful scientific prediction. From Velikovsky’s general thesis and the calculations just described above, it is clear that Venus should be saturated with manna, a carbohydrate. Velikovsky says (page x) that “the presence of hydrocarbon gases and dust in the cloud envelope of Venus would constitute a crucial test” for his ideas. It is also not clear whether “dust” in the foregoing quotation refers to hydrocarbon dust or just ordinary silicate dust. On the same page Velikovsky quotes himself as saying, “On the basis of this research, I assume that Venus must be rich in petroleum gases,” which seems to be an unambiguous reference to the components of natural gas, such as methane, ethane, ethylene and acetylene.