Chapter 4 The Origin of Life

The water, as the almighty solvent, is essential to all living creatures on earth. The property of water that can dissolve anything spreads the nutrition through out the body and also to gathers waste products.

Plants absorb nutrition from its roots. But again, such could not be possible without the water's property as a solvent. Water, although abundant on earth and also essential to life, becomes a rare substance once we look beyond earth.

Recently, it was confirmed that Mars was also once abundant with water. The satellites of Venus, Europa and Ganymede are presumed to have water, but in solid state of ice. Liquid water remains very precious in the universe.

Why does water exist abundantly only on earth? According to scientists, earth maintained moderate distance from the sun, enabling the earth environment to maintain certain temperature so that liquid water could exist. They say if the temperature were lower, the water would be locked up inside the bedrocks. If higher, every water would evaporate into space. Could such be true?

Or could it be that the earth was able to maintain moderate temperature owing to the abundant water?

I stand on the latter case because water does have a function to level the temperature. In liquid water, molecules move freely. When a part of it experiences some change in temperature, then the weight changes, causing a current. Such current would soon level out the temperature. On the other hand, since solid bodies can't cause a current, change in temperature occurring in some parts of it can only be dispersed through heat conduction. Therefore, only the surface would be heated excessively while its depth will be heated only after a while.

Applying the above account to Earth, thanks to the wide ocean, earth will be able to cope with the change in the incoming heat without experiencing major change because the wide ocean area will absorb such change leaving only minor change in the temperature of the water.

On the contrary, if there were no oceans but all lands, the temperature of its surface will change accordingly to the incoming heat from the sun that it may be heated or cooled excessively. If such happens, the environment would be far from adaptable for any living creature to exist. This is what exactly is happening on the moon, which is in the same distance from the sun as the earth. Some parts of the earth are experiencing something similar, but not as extreme. For example, the difference in temperature of day and night are only about 10-15 degrees in Japan. This is because the oceans surrounding it functions as the regulators. But places like Mongol located deep in the continent, can't benefit from such regulator, thus experience extreme temperature difference between daytime which may exceed 50 degrees and nighttime which reaches below zero.

Such a notion may lead us to think that without water, our earth would not be able to maintain its temperature at a constant level. But the existence of water depends on a stable temperature. Which comes first, the chicken or the egg?

Translated by Rie Ishida