Chapter 30 world's largest membrane

Standing on the moon and looking at the earth from a distance, the thing that makes people hold their breath is that it is alive.The dry, battered surface of the moon in the foreground looks as dead as bones, judging by the photo.Floating high in the sky, wrapped in that moist, luminous membrane of blue sky, was the rising earth.On this side of the vast universe, it is the only living creature overflowing with vitality.If you can look long enough, you will see large swirling clouds half-covering the land, and the land looming in the clouds.If you can see the evolution from very ancient geological time, you will see the continents themselves are also moving, you can see them drifting on the plates of the earth's crust driven by the ground fire.Earth appears to be an organized, self-contained organism, laden with information, that uses the sun with enviable skill.

In biology, it is membranes that bring order out of disorder.You have to be able to capture and hold energy, store up the exact amount needed, and then release it in a balanced manner.A cell does this, and so do the organelles within it.Every collection of life is swaying in the solar particle flow, grabbing energy from the sun's metabolites.In order to live, you must be able to fight balance, be able to maintain imbalance, build up energy to resist the increase of entropy.In a world like ours, only membranes can handle such affairs. After the earth came alive, it began to construct its own membrane, the basic purpose of which is to process solar energy.In the beginning, in the prebiotic period when peptides and nucleotides were synthesized from inorganic components in water, there was nothing to block ultraviolet radiation except water.The original thin atmosphere came directly from the exhaust process of the Earth as it slowly cooled, with only wisps and barely perceptible oxygen in it.Theoretically speaking, water vapor can also undergo photolysis under the action of ultraviolet rays to generate oxygen, but the amount will not be much.As Urey (Urey, HC, 1893-1981, US) pointed out, this process will have a self-limiting effect, because the wavelength required for photolysis is exactly the wavelength shielded by oxygen.Oxygen production is cut off almost immediately.

The production of oxygen awaits the emergence of photosynthetic cells.The environment in which they live must have sufficient visible light for photosynthesis, and at the same time must be sheltered from the deadly ultraviolet rays.Berkner (Berkner, LV, 1905～1967, the United States) and Marshall (Marshall) deduced that green cells must survive in water about ten meters deep, probably in ponds, where the water is relatively shallow and there is no Very strong convection (the ocean cannot be the origin of life). You could say that the release of oxygen into the atmosphere is a result of evolution.You can also go the other way and say that evolution is the result of the availability of oxygen.You can say anything.Once photosynthetic cells—likely the equivalent of today's blue-green algae—appeared, the future of Earth's breathing machinery took shape.In the past, when the level of oxygen in the atmosphere increased to one percent of today's oxygen concentration, the anaerobic organisms on the earth were threatened. In the next step, there will inevitably be mutants with oxidation systems and ATP (adenosine triphosphate) .With this, we have reached a stage of explosive development where thousands of species of breathing life, including multicellular life forms, can multiply.

Berkner proposes that there were two such nascent explosions, as large-scale embryological transformations; both leaps depended on oxygen levels breaking through a certain critical value.In the first leap, the concentration of oxygen reached one percent of the current level, which blocked considerable ultraviolet rays and enabled cells to migrate to the surface waters of rivers, lakes, and oceans.This change occurred during the Early Paleozoic Era, about 600 million years ago, as evidenced by a sharp increase in marine fossils from this period in the geological record.The second leap occurred when the concentration of oxygen reached 10 percent of today's level, about 400 million years ago. At this time, an ozone layer strong enough to reduce ultraviolet radiation has been formed, so that life can emerge from the water. Come out and settle on land.From then on, the development of living things is unimpeded, and nothing can limit the development of species except the limit of biological creativity.

One more thing shows how blessed we are.Oxygen absorbs the most lethal part of the ultraviolet spectrum band to nucleic acids and proteins, while at the same time it allows the visible light needed for photosynthesis to pass through sufficiently.We wouldn't have evolved this way if it weren't for this semipermeability of oxygen. In a sense, the earth also breathes.Berkner proposed that there may be a cycle of oxygen production and carbon dioxide consumption, which depends on the relative abundance of plants and animals on Earth, and that several ice ages represent a pause in breathing.Overgrowth of plants may have raised oxygen levels higher than today's concentrations, causing a corresponding depletion of carbon dioxide.The drop in carbon dioxide levels may have damaged the "greenhouse effect" of the atmosphere.The carbon dioxide greenhouse effect keeps the heat from the sun for the atmosphere, and when the greenhouse is damaged, the heat is radiated away from the surface.The drop in temperature, in turn, suppresses the growth of a large proportion of organisms.A long sigh, the oxygen level dropped by maybe ninety percent.This, Berkner speculates, spelled disaster for the large reptiles.Their size was not a problem in an oxygen-rich atmosphere, but at this time they suffered from oxygen depletion.

Right now, we have a thin layer of ozone thirty miles above the Earth's surface.It protects us from deadly UV rays.We are safe, well ventilated and safe and sound.If we can avoid technologies that could mess with the ozone layer, or that could change the concentration of carbon dioxide, oxygen isn't a big problem for us, unless we let go of enough atomic explosions to kill the green cells in the ocean.If we do this, of course, we are pulling the noose around our own necks. The atmosphere is so utterly impersonal that it would have been difficult to get emotionally attached to it.However, it is really a part of life and a product of life, like wine and bread.Overall, Sky is a miraculous achievement.It is functioning, and as far as its designed function is concerned, it is functioning as well as everything in nature.I don't believe that anyone can imagine any way to make it more perfect. All we can do is occasionally move a certain cloud from one place to another.It doesn't make sense to use "accidental" to explain such a magnificent building as the sky.The appearance of chloroplasts may be a bit of luck, however, once these things appear, the evolution of the sky is absolutely doomed. "Accidentally" implies that there is an alternative, that there are other possibilities, different ways out."Accident" may have played a role in details such as gills, swim bladder, and forebrain.But the creation of the sky will not be like this.There is simply no other way out for it.

We should praise the sky as it is now: in its size, in its perfection of function, it is the greatest and incomparable collaboration of all things in nature. It breathes for us.It also protects us for our joy.Every day, millions of meteorites fall into the outer layer of this membrane, and they are reduced to nothing by friction.Without this barrier, the surface of our earth would have been reduced to powder under the bombardment of meteors, just like the surface of the moon.Although our receptors are not yet sharp enough to hear the bombardment, we feel it, and we take comfort in the fact that the sound is right above our heads, like the night rain beating on the roof.