Chapter 6 Chapter 5 Solar Generator

Except for the earth, there is no object in the solar system that has the most important relationship with human life than the sun.By its incomparable gravitational force it exerts a stabilizing effect on the delicate dynamics of the planetary motions; and by its life-giving radiation it prevents the earth from becoming a desert of ice and snow. A few years ago, a whimsical science fiction writer hypothesized that the world would perish if the sun didn't emit its warming rays.He also assumed that another star was coming towards the solar system, passing nearby, disturbing the orbits of the planets.The star's gravity upsets the delicate balance of the entire solar system.The earth is pulled by it, out of the sun's grasp, drifting in the eternal cold of space.

Deprived of the warming energy from the sun, Earth's oceans began to freeze into ice.The earth was soon covered under a solid crust of ice, the empty spaces filled with pools of liquid oxygen and hydrogen, steaming, the poor remnants of an atmosphere.The pools also gradually froze solid.The once gigantic surface of the sun, shrunk to the size of a pinhead, shone faintly and dimly on the desolate surface of the earth.Another century and the sun will be nothing more than a cold light among the distant stars.At that time, human beings exhausted their meager resources, struggled less and less, and finally perished.

The science fiction writer's harrowing vision may never become true.The earth is firmly attached to its orbit around the sun that warms all things.The space between the stars is so large that the possibility of any two stars colliding or passing close to each other is almost non-existent. But the novelist has shown in sensational fashion just how dependent all life on Earth is on the constant supply of solar energy.According to the story, it was not the brutal onslaught of cold that wiped out life.It says that the peoples of all countries on the earth have known their future for a long time, astronomers have calculated what will happen, and the world's politicians have made large-scale preparations for the survival of mankind, using the heat of the earth's interior .The peoples of the world live in caves, hundreds of yards below the surface, protected from the cold by a thick layer of rock overhead.But they finally died of starvation.Without sunlight, plants on the earth cannot carry out the activities of making food.The eternal cycle of life is thus severed.

The radiant energy of the sun is the source of the power that drives all life processes.In fact, it is the most fundamental source of motivation for nearly everything on Earth. When we drive a car, we use fossilized solar energy to propel the vehicle.The gasoline in the tank is refined from crude oil, which was formed over a long period of millions of years beneath the earth's surface.For eons ago, living organisms enjoyed the warming rays of the sun, which shone on them and gave them a chance to live and grow.When they die, in some areas their rotting bodies accumulate in great numbers and are buried under sand and silt, which turns into rock, and the oil from the body gradually fills the spaces between the sand grains.

When we flip the switch of the TV, it is the solar energy that provides the power again.The electricity that powers our cities' power lines comes from power stations that turn coal into electricity.Coal is also fossilized solar energy.It is the remains of a vast number of plants that lived in ancient geological times, used solar energy to form their tissues, and then died, gradually accumulating more and more sand and mud on their bodies.The pressure slowly carbonizes them into the black, flammable coal we know. Power stations can also draw energy from water stored in dikes.These waters also represent solar energy.Every day of the year, the sun evaporates about one trillion tons of water from the sea, turns it into vapor, and enters the atmosphere. Most of this huge amount of water soon turns into rain and falls on the continents.Tens of thousands of tons of rainwater enter the reservoir formed by the embankment from the stream.The dam has aqueducts through which the water flows continuously down to the blades of the large turbines that turn the generators that generate electricity for us to use.

The farmer uses a windmill to pump groundwater into an elevated tank and pipes to his house and barn.The water pump is driven by a windmill.The blades of a windmill are moved by the wind.Wind is caused by the movement of air currents, which in turn are caused by the uneven heat that sunlight imparts to the ground and air: heated air expands and rises, and cooled air contracts and sinks.So in the end, it's solar power that powers the farmer's water pump. Sometimes huge amounts of stored solar energy are released in concentrated, destructive ways.In the end, the sun is responsible for cyclones, hurricanes, floods, and forest fires.We are often subjected to tragic attacks by natural forces.It is difficult for us to recognize the energies emanating from these terrible forces that lie hidden in the friendly rays of the sun.

A tiny fraction of the total amount of energy acting on the surface of the earth does not originate in the sun.The avalanche of rock rolling down the hillside was powered by the internal forces of the earth that had piled up the mountains in the first place.The energy of earthquakes also comes from the earth itself.The source of volcanoes, geysers and hot springs is the heat within the earth which is produced in part by radiation.In the end, the rising of the tide is mainly driven by the moon; the sun contributes only about a third of the force to the height of the tide.The sum of all the energies mentioned above, although each of them is a huge force, is only a small part of the huge energy that is on display before our eyes.The rays of the sun override all the rest.

The total amount of radioactive energy that falls on the earth every day is staggeringly large, but it is only a tiny, tiny fraction of the total energy that the sun dumps into space every second.Seen from the sun, the earth is a tiny point the size of a small silver coin seven hundred feet away.Therefore, of the vast amount of energy emitted from the sun in all directions, only a tiny fraction reaches our earth; almost all of the solar energy is lost somewhere in the infinite depths of space. The sun occupies a huge space, its rays are overwhelming, and its heat is scorching.To a great extent beyond it, it is above all the brightest star in the sky.Even from the unimaginably distant places in space, the sun is a visible star, although not very bright.But as far as human beings are concerned, almost all of this enormous amount of energy has been unjustly wasted, and has been wasted since the birth of the sun.

How small is the share of solar energy that the earth receives? Suppose the sun supplies us with radiant energy not continuously as a stream but in bursts, each burst lasting only one second.In this way, the sun only needs to emit one second of heat every seventy years to give back the energy it wants to distribute to the earth.Of course, fortunately we don't get the sun's heat all at once.If so, the earth would be vaporized in the blink of an eye, even though it is 93 million miles from the sun. Why does the sun emit such huge energy so often and continuously?The reason is that its surface is extremely hot.If any object is heated to a high temperature, it will emit a considerable amount of energy. The higher the temperature, the more energy it emits.Even the human body emits energy by radiation: our skin emits three ten-thousandths of a horsepower per square inch of surface area, and it is at this rate that the whole body loses energy.A pile of hot charcoal produces much more energy because it is much hotter: it produces a tenth of a horsepower per square inch.That's quite a release of energy, and it's no wonder so many picnickers burn their fingers trying to grill frankfurters.

And what about the sun?At its surface, the temperature exceeds 10,000 degrees Fahrenheit, and it can deliver power at a rate of fifty-four horsepower per square inch.The total amount of electricity produced in the United States in 1960 was about 800 billion kilowatt-hours.This annual production of energy is equivalent to the energy emitted by a small spot on the surface of the sun about the size of ten tennis courts. Why can the sun continuously emit so much astonishingly huge energy?Because its surface keeps extremely high temperature all the time.If we take a hot piece of iron out of the furnace, it will cool down a lot in a fraction of a second.Its color quickly changes to cherry red, and after a while it becomes dark red.After a minute or two, it didn't glow at all.So why doesn't the Sun cool down, even though it radiates heat at such an astonishing rate?The reason, of course, is that the heat lost on its surface is continuously replenished by the heat provided by its interior.

Then, the fire power that keeps the solar power plant running forever cannot be of the nature of coal fire.As early as a hundred years ago, someone had already seen this truth, and for the first time recorded the huge amount of energy emitted by the sun with specific scientific figures.It was calculated that if the sun were an ordinary fire, it could not last long, even if it was made of high-grade coal burning in pure oxygen, which was one of the best combustible combinations known at the time.If the sun were an ordinary fire, it would burn to a mass of ashes even during recorded history.This is not the case, we know that the age of the sun is by no means just a few thousand years.It has been emitting energy on this monstrous scale for billions of years, more than a million times longer than a star made entirely of coal or gasoline can burn.Inside the sun, buried beneath the deep layer of hot gas, must be an astonishing reservoir of energy. It seems impossible to study the interior of such a huge and extremely large object as the sun.How can we tell what lies beneath a layer of hot gas hundreds of thousands of miles thick?Besides, we are almost 100 million miles from the surface of the sun.It is remarkable that physicists and astronomers, in spite of all the above-mentioned difficulties, were able to do the math and work out what was going on in the sun's deep core. What guides us to what's going on at the heart of the Sun is the simple fact that the Sun is clearly a stable structure.It neither exploded nor collapsed under its own enormous weight.The sun is as heavy as 330,000 earths, and its vast mass, mostly hydrogen and helium, is held together by gravity into a huge spherical shape.But what keeps the sun from collapsing?In any case, gas is always compressible, and the innermost core of the sun must bear a terrible weight, because almost all the mass of the sun is supported by the core.We should think that the interior of the sun cannot bear such a heavy load and has to be compressed into a solid body.In fact it is not.A mass of gas under extreme pressure can itself exert extreme pressure outwards, and thus can bear extremely heavy loads. The car is actually supported by the compressed air in the tires: it's really on air.Furthermore, the load capacity of the compressed gas can be increased.We can increase the density of the air inside the tire by pushing more air into the limited space of the inner tube; in addition, we can increase the temperature of the air inside the tire.Both of these methods will increase the internal pressure, but it is the tire pressure in pounds per square inch that determines the load capacity of the vehicle. According to the logic of this car tire, physicists and astronomers can know something about the interior of the sun.Obviously, each layer of gas that makes up the sun's body must bear the entire weight of its outer layers.But this requires that the internal pressure of each layer of gas has an appropriate value, otherwise it will be overwhelmed by the weight of the layers above.However, the pressure from below should not be too high. If it is too high, this layer of gas will not be able to bear it, and it will lift up the upper layers, causing the sun to explode.So the sun's pressure all over the body, inside and outside, has to be just right.All that astronomers have to do is to imagine the proper density and the proper temperature for each layer of gas in the sun, and these values ​​will make a stable sun, one that neither collapses nor explodes. Designing and building the sun is a fascinating business with only one difficulty, and the example of car tires makes it clear.If the temperature of the air inside the tire is high, even though its density is low, it can produce sufficient load capacity; we can press more air into the tire to increase its density, so although its temperature is low, the load capacity is still the same.By the same token, astronomers don't understand how dense and hot each layer of gas inside the sun should be.If the density they assume is high, the temperature can be lower; conversely, if they want to make a layer of low density, they only need to make it have a higher temperature. However, the above is only one way to solve this problem, and the existence of the sun clearly shows this situation.We were able to find this solution because we know how much matter is in the sun.As astronomers design one layer and then the next, they must gradually assume their densities, so that when they finally reach the Sun's core, all of the Sun's matter is at work.If the density of the layers they designed increases too quickly, too much material will be consumed in the outer layers, and there will be no extra material to fill when it finally reaches the core.Conversely, if they designed the density to increase layer by layer too slowly, some material would be left with nowhere to use.So there can only be one solution, and the core temperature of the sun determined by this method is frightening: up to 38 million degrees Fahrenheit. The most interesting implication of this number is that when the temperature reaches such a high level, the hydrogen gas will burn with an enormous amount of radioactive energy.But it is a special kind of fire.It is not the fire we usually see, such as a stove, a burning wood pile, or a gasoline fire.Hydrogen, when subjected to millions of degrees of heat, ignites the destructive flames of an atomic fire. At this high temperature, the nuclei of the hydrogen atoms begin to melt, or stick together, and the simpler particles that make up the hydrogen nuclei form the heavier nuclei.Whenever two nuclei fuse, a radiation is emitted with a huge amount of energy.The main ashes of this terrible atomic fire are helium.The hydrogen hidden deep in the core of the sun transforms into helium, releasing a huge amount of radiant energy.It takes tens of millions of degrees of high temperature to release energy from matter. More than fifty years ago, the famous physicist Albert.Einstein showed that matter is really highly concentrated energy.There is an enormous amount of energy contained in just one ounce of matter.If all these energies are released, it will be equal to the heat produced by burning more than 500,000 tons of coal.To generate such a large amount of heat, an entire ounce of matter must be converted into radioactive energy.When hydrogen was transformed into helium in the terrible heat of the sun's core, some of the matter involved was indeed lost.When a thousand pounds of hydrogen is converted to helium, the resulting helium weighs only 992 pounds because the other eight pounds of matter have been converted to radioactive energy. The stream of energy rushed out from the hot atomic furnace at the core of the sun, and passed through the sun's huge body in all directions.Later, the stream of radioactive energy finally reached the surface to replace the energy lost to space by the outermost layers of the sun. The hydrogen consumed every second reaches 600 million tons; but almost all of it turns into helium and reappears.Almost five million tons of material are actually lost every second.These five million tons of matter are converted into radioactive energy and flow into space.But the mass of the sun is extremely huge. Since the birth of the earth, the mass consumed by the sun is only 1.5%.Although the sun wastes energy to an unimaginable degree, it still has abundantly stored a huge amount of matter, which can be continuously converted into energy in the next tens of billions of years.Human beings need not worry that the sun will stop shining. The fire that burns in the fiery core of the sun is the very kind of fire that makes hydrogen bombs so horribly destructive.When a normal uranium bomb or plutonium bomb explodes, an extremely high temperature is generated in the center of the explosion. Such a huge temperature can make a mass of hydrogen fuse into helium, and release terrible power during the change process.This is how the frightening hydrogen bomb explodes, which is a thousand times more violent than ordinary atomic bombs.The old atomic bombs only acted as triggers when the hydrogen got hot enough and exploded on its own.Atomic physicists call hydrogen bombs thermonuclear weapons because hydrogen nuclei can only be transformed into helium and release energy when exposed to extremely high temperatures.Fortunately, when the hydrogen bomb explodes, it only takes a very short time, that is, a fraction of a second, for the temperature to drop. As soon as the temperature drops, the terrible explosion of hydrogen stops immediately.Nothing can preserve the temperature of the hydrogen bomb, because the explosion was so violent that everything was blown away by it. At the core of the Sun is an ever-burning atomic fire, the equivalent of the center of an exploding hydrogen bomb.In the extremely high temperature of the sun's core, hydrogen burns endlessly, because the heat cannot escape in a violent explosion, it can only slowly leak out bit by bit.The great weight of the sun's body presses down on the core, keeping the atomic furnace alive forever.If a fist-sized mass of terribly hot gas at the core of the sun had suddenly escaped its cage, it would explode instantly with the furious force of a hydrogen bomb. Surrounded by heavy and thick walls of gas, the berserk core of the sun emitted enormous amounts of atomic energy.Energy rushes through the deep outer layer, leaking into space.The sun's rays gradually become thinner on the long way to the earth, and finally reach the earth.When we see the warm and lovely sunshine, we never think that the birthplace of solar energy has such terrible heat that can destroy everything.