The Original Water Cycle
Premise one: The planets all started out with about the same materials.
They all were more or less gas giants. The first question is of course why? One reason could be that since the Sun and the planets started as just one giant nebula and that since the source is the same for all the result (the formation of the planets) would be the same. Another argument in favor of similar patterns is that our universe is chaotic, this is to say that the closer you look at a fractal world the same pattern is repeated. So we look at the early solar system and see the Sun (a big ball of gas) surrounded by other balls of gas (the planets) which then are surrounded by their satellites, etc. Okay, this differs slightly with standard theories of our solar system in that it implies that Earth, Venus, Mars, even Mercury had many moons. Where did they go? And these massive atmospheres where are they now? I donít want to deal with the moons of the terrestrial planets a lot. After all there is not much evidence for their existence. But, here is one explanation; the moons like many man made satellites would become perturbed when the Sun became more active. The solar wind or the corona would eventually cause these planetoids, rocks and dust to crash into their respective planets. There is evidence of long term bombardments on the terrestrial planets and the Moon. I never liked the explanations as to why these catastrophes took place, but that is neither here nor there. Letís get back to the task at hand. The terrestrial planets had atmospheres like Jupiter?
Well, this is not really an original idea. __________ and ____________ at the Harvard Smithsonian Observatory have suggested that Earth resembled Jupiter early in its history. They said that isotopes hydrogen and helium found in the rocks support their theory.
So the Sun just blasted the antediluvian atmospheres off into space? Maybe, that is argueablely the case with Mars and Mercury. But if you look at the massive atmosphere of Venus and count the air and the oceans of Earth together perhaps those atmospheres were not simply launched into space.
Which brings us to premise two: The Earth had a massive atmosphere of carbon dioxide, methane, ammonia, water vapor and perhaps quite a bit of hydrogen and helium.* (I know that I am going to get in a lot of hot water with the Earth Science boys thanks to conversations I have had with James Walker at the University of Michigan) How much? There is no way to tell. But there is something that might give us an indication. It is called the faint young Sun warm Earth paradox. The Sun four billion years ago was not as energetic as it is today. If everything else stayed the same then Earth would had been basically frozen, yet there is evidence of liquid water and life on our planet at that time.
Now, if you had an atmosphere of carbon dioxide methane, etc. at, I donít know maybe 10 bars (ten times the pressure today) you would have a ę green house effect Ľ that could warm our planet to the aforementioned temperatures for water to run free. But that greenhouse warming would be somewhat offset by clouds of carbon dioxide in the upper reaches of the atmosphere and ordinary water clouds a little lower down which would reflect a lot of energy into space.(see The Evolution of the Martian Climate, American Scientist volume 84, page 445) I am not qualified to calculate where the balance of these two factors; greenhouse effect and solar reflection would lead. For the interest of continuing this speculative piece letís assume it is as thick as the atmosphere of Venus or around 90 bars. Why not ? Venus is often called the sister of Earth with a density 95% that of Earth. If you vaporized all of the water on Earth the resulting atmospheric pressure would be much higher than 90 bars.
Common sense says that for life to evolve starting conditions had to be the warm wet sea. Well, what if common sense is wrong? What if it is not a warm wet sea but sort of a very hot lake under enormous pressures. Crazy? Not really, quite a few people have suggested that the place for life to start is the undersea vents where of course pressure is intense and temperatures are as high as 110 degrees Celsius. (The water stays liquid because of the enormous pressure.) It is not that farfetched to replace the awful pressure of the oceans with that of the atmosphere. If this scenario is true than there is a good chance that Earth did not have all that much water in the beginning. That is why I said lake and not ocean. It has a sort of logic to it:
Lake bottoms are usually less salty that oceanís. Our cells are less salty than sea water. ( I know I am running once again in the face of so many people who have suggested that the early seas were less salty than now.)
Also, if I remember correct the fossils of the oldest forms of life were the mats of bacteria that live in the shallows.
Letís examine that atmosphere when life starts to produce oxygen. The methane becomes water and carbon dioxide. Ammonia would become water and Nitrogen gas. The carbon dioxide would be used by the plants along with water to become hydrocarbons (see Carl Saganís famous equation of life in his book ę The Search for Extraterrestrial Life Ľ) and it would also dissolve in the water and react with the ions in rocks and precipitate out.
In the standard theory of atmosphere formation at around the time life was forming 4 billion years ago the Earthís atmosphere was supposed to be carbon dioxide and nitrogen. Now if there was a water cycle like we have today with the same extent of water as we have today well, there are indications that there wouldnít be much carbon dioxide left by 4 billion years because it would have a precipitated out. Now if there really wasnít that much water in the beginning well then you can keep the CO2.
Another problem for the geologists who believe in a CO2 N2 atmosphere 4 billion years ago is all the life scientists who have done experiments creating amino acids and the other precursors of life. Well, none of them postulated an atmosphere of CO2 and N2. Without an atmosphere with ammonia and methane none of their experiments produce the requisite compounds. That doesnít prove that what I suggest happened did happen, but it does lend a little more weight to my side of the scale. Okay everybody, whatís wrong with this idea?