This article is based on answering an invitation from a netizen. The original title is: Everywhere on the sun is undergoing nuclear fusion and all the time. So what is the initial equivalent of each nuclear fusion explosion on the sun?
I have published many articles explaining the issue of nuclear fusion inside the sun, but seeing that some friends still don’t understand it, and invited to answer such questions, I feel obliged to say it again. Don't think it's just repeating the same old tune. In fact, each answer is a process of learning together with netizens. We try to use new perspectives and knowledge to share this old question with you . Welcome new and old friends to read it patiently. Put forward more valuable opinions.
First of all, I told this friend that solar nuclear fusion does not happen everywhere.
Nuclear fusion does not happen randomly, but requires extreme conditions, such as extremely high pressure or extremely high temperature. Man-made controllable nuclear fusion on the earth requires a high temperature of hundreds of millions of degrees to continue. Compared with our earth, the sun has a special condition, which is high pressure, so the temperature of continuous nuclear fusion does not need to be so high, but the location of nuclear fusion must be in the core to occur.
The sun is a huge plasma ball mainly composed of hydrogen and helium elements, with a radius of about 700,000 kilometers. The universal gravitational force makes this plasma sphere continuously shrink toward the core, so that about 300 billion atmospheres of pressure and a temperature of 15 million K are formed at the core. The high temperature peels off, exposing the bare nucleus, under the pressure and high temperature, the nucleus and the nucleus continue to collide violently, and nuclear fusion , that is, nuclear fusion, is ignited. The nuclear fusion zone of
is at the core of about 1/4 of the sun's radius.
The process of solar nuclear fusion is relatively complicated, so I won’t expand on it today. Simply put, four hydrogen nuclei are fused into one helium nucleus, and during this aggregation process, there will be a part of mass loss. How big is this loss? We can figure it out simply. The main thing involved in nuclear fusion is the isotope protium of hydrogen, the atomic weight of protium is 1.008, and the atomic weight of four protium nuclei adds up to 4.032; the atomic weight of helium-4 after nuclear fusion fusion is 4.003, which reduces the mass of 0.029, which is about 0.72% of the mass of hydrogen nuclei involved in nuclear fusion. Where did these masses
go? It turned out to be radiated out in the form of photon and neutrino . The radiated mass is energy, how big is this energy? This has to use the mass-energy equation of Einstein .
The mass-energy equation can be used to calculate the energy of solar nuclear fusion
The mass-energy equation is one of Einstein's greatest discoveries. This equation unifies the isolation state of mass and energy in classical mechanics and reveals the equality of mass and energy in matter. price exchange relationship. The simple expression of
mass-energy equation is: E=MC^2. Here E stands for energy, unit J (joule); M stands for the static mass of the object, unit kg (kilogram), C stands for the speed of light in vacuum, unit m/s (meter/second).
This is a formula that has the beauty of simplicity, but contains the most profound laws of nature. According to this formula, we can see that there is a huge amount of energy in the mass of matter. As long as 1kg of matter is completely converted into energy, you can get 9* 10^16J, which is equivalent to the power of 25 billion kWh or 21.51 million tons of TNT explosives.
and the core of the sun produces about 600 million tons of hydrogen that participates in nuclear fusion every second, and loses 0.72% of its mass, which is 4.32 million tons. All of these masses are converted into energy of about 3.9*10^26J, which is equivalent to 1080 billion degrees Electricity, or 930 gigatons of explosives, that is, the energy of more than 7 trillion Hiroshima atomic bombs exploded at the same time.
The sun is bursting out such huge energy every moment and every second. Some people worry that such a huge consumption will soon burn out the sun? whyNow the sun is 4.6 billion years old, that is, it has been burned for 4.6 billion years, and it has not been burned up. It is said that it can burn for more than 5 billion years? In fact, if we just do some calculations, we will know that the sun will not burn out when it dies, but only burnt some skins.
Why can the sun burn for 10 billion years? The total mass of
the sun is about 2*10^30 kg, hydrogen element accounts for about 75% of the total mass, helium element accounts for about 24%, and other heavy elements account for about 1%. The sun has about 600 million tons of hydrogen to participate in nuclear fusion every second, and there are 31557600 seconds in a year, and the hydrogen involved in nuclear fusion needs about 1.9*10^16 (190 billion) tons, and it takes about 1.9*10^10 billion years 26 tons, which is 1.9*10^29 kg.
From the above calculation results, we can see that if the nuclear fusion of the sun continues from the beginning to death, the hydrogen consumed by the 10 billion-year lifespan is equivalent to less than 10% of the total mass of the sun, which is equivalent to the total hydrogen in the sun. The mass is about 12.67%. But these hydrogens are not lost, but converted into helium nuclei and stored in the core of the sun. What is really consumed is only about 4.32 million tons of material mass per second, which is about 1.36*10^27 kg in 10 billion years. These mass losses account for 0.068% of the total mass of the sun, which is less than 7/10,000.
That is to say, the sun loses 4.32 million tons of mass converted into energy every second. When 10 billion years come to an end, the mass loss is only less than 7/10,000. Now you have witnessed the power of mass-energy conversion, you know Why do humans spend so much money and money to develop nuclear fusion power generation?
The sun's need to consume 600 million tons of hydrogen per second is not an arbitrary estimate. Scientists have many ways to understand it. For example, through a star with such a large mass as the sun, the core pressure and temperature lead to accurate calculation of the intensity of nuclear fusion; for example, the sun’s heat is collected per square meter of the earth’s equator, so as to calculate the total electromagnetic radiation of the sun, and calculate these energies according to the mass-energy equation How much mass conversion is required, and then calculate the total amount of hydrogen that needs to be consumed based on the mass loss of hydrogen nuclear fusion.
is a long story, and it is another topic, so I won’t expand on it today. Why is
solar nuclear fusion always controllable and not exploded?
Many people have this question, that is, the solar nuclear fusion is not covered by a hard shell, why is it not like the hydrogen bomb and exploded all at once? In fact, this is a misunderstanding. Not only does the sun have a shell, but this shell is also very powerful, that is, the huge mass and volume of the sun form a huge shell that restricts the nuclear fusion at the core of the sun.
Gravity causes the huge mass of the sun to shrink toward the core continuously, and this objectively forms a thick outer shell. Therefore, the restriction method of the nuclear fusion of the sun is the gravity restriction. Nuclear fusion is ignited by high temperature and high pressure due to the huge mass of the sun constantly pressing on the center. After nuclear fusion is ignited, a huge radiation pressure will be generated. If there is no huge gravitational pressure of the sun to restrain this radiation pressure, the sun will burst like a hydrogen bomb.
The huge radiation pressure produced by nuclear fusion will expand to the periphery and generate huge tension. When this tension just resists the gravitational pressure of the mass, the gravitational pressure and radiation pressure will achieve a balance, and the huge volume of the sun can no longer shrink toward the center. The radiation is also suppressed and cannot escape. This balance is the main sequence star stage of the sun. For stars with the mass of the sun, this main sequence star stage can last for 10 billion years.
Flashback before the end of the sun
When the hydrogen in the core burns out in 10 billion years, nuclear fusion will go out. Without the support of huge radiation pressure, the gravitational centripetal pressure, which has been tense for 10 billion years, has an opportunity to shrink to the core at a high speed in an instant. The special term is collapse, which means it collapses to the core at an extremely fast speed. In this way, the core pressure and temperature increase suddenly, reaching more than 100 million degrees, and a higher level of helium fusion is ignited.
At this time, the sun will become a red giant star, its radius will expand by 200 to 300 times, and it will enter the old retroreflection stage. At this stage, the nuclearFusion stops and ignites will be repeated, the star is extremely unstable, and each level of fusion that ignites heavier nuclei requires a higher temperature. Eventually the sun is too exhausted to ignite the fusion of carbon nuclei and later heavy nuclei, and nuclear fusion finally stops.
But at this time, the gravitational force of the sun can no longer pull the overexpanded peripheral gas matter, and these peripheral matter will gradually dissipate and become a new nebula in space, leaving only a dense carbon core at the core, which is the white dwarf star . This white dwarf is only the size of the earth, but its mass is about 0.6 times that of the sun, so its density is as high as more than 1 ton per cubic centimeter.
How does nuclear fusion radiant energy in the core of the sun come to the surface and radiate into space?
Now we need to talk about the structure of the sun. The structure of the sun is a bit like a peach. The core of the peach is the nuclear fusion area of the sun. The huge energy released by nuclear fusion spreads outward in the form of electromagnetic radiation, first passing through the radiation layer. The radiation layer is a bit like the flesh of a peach, occupying the largest space, starting from 1/4 of the sun's radius and reaching 86% of the radius.
The radius of the sun is about 700,000 km, and 1/4 of the nuclear radiation area is a spherical area from the core particle to a radius of 175,000 km, and the nuclear fusion that goes on every moment is going on in this area; The energy of fusion reaches 60.2 kilometers away from the center of mass through the radiation zone, such a large circle is the radiation zone; with this as the boundary, it is the troposphere , that is, it enters the subcutaneous tissue of the peach.
The so-called troposphere is the area where the hot area rushes upwards, the cold area descends, and the area continuously churns up and down. This layer accounts for nearly 100,000 kilometers in the radius of the sun. Further up is the photosphere layer, which is already the cortex of the sun, of course it is not the epidermis, but the thin layer below the epidermis, which is called the dermis if it is compared with the animal skin.
The photosphere is only about 500km long, just like a cover of the sun covering the turbulent troposphere, all the visible light of the sun is emitted from this photosphere, so the boundary of the sun is bounded by the photosphere. The surface temperature of the sun is about 5777K, which refers to the temperature here.
There is a layer of chromosphere on the outside of the photosphere, which is about 2000km thick, which is the epidermis of the sun. The strange thing is that the temperature of the sun decreases gradually from the inside to the outside, all the way to the photosphere. But when it reaches the chromosphere, it gradually rises, and when it reaches the top of the chromosphere, the temperature can be as high as 20000K.
The outer layer of the chromosphere is the atmosphere of the sun, also called the corona. The corona is composed of high-temperature and low-density plasma, a bit like the flame of a furnace, flickering, the closer to the sun, the denser and hotter, the temperature can reach millions of degrees; to the edge of the solar system.
The photons of the sun walk randomly
The solar energy is transferred out layer by layer in this way, and these energies are transferred out through the photons. Photons are born from the mass-energy conversion of core nuclear fusion, and rush out as soon as they are born. They can reach 300,000 kilometers per second in a vacuum, but it is different in the medium.
is 700,000 kilometers from the center of the sun to the surface. Originally, photons only need to travel for 2 seconds to go out, but the sun is full of protons, and photons are "hospitable". Perform an identity exchange, so that you will get dizzy after a turn, the direction will change, and you may go back. This way of walking is stumbling, taking three steps forward and two steps back. People call this walking method "photon random walk".
The average distance between each proton inside the sun is only 1 angstrom. If a photon encounters each proton and has to "chatter" for a while, someone calculates that it will take 3.9*10^37 steps, which will take 400 billion years. The lifespan of the universe is only 13.8 billion years, and the lifespan of the sun is only 4.6 billion years. Could it be that a photon hasn’t come out yet?
is actually not like this, the density distribution of protons in the sun is not uniform, some places are sparse, and some places are dense. Since it is a random walk, some are fast and some are slow, and each photon does not need to be "close" to all protons. In this way, the fast tens of thousands of years and the slow hundreds of thousands of years will come out.
But there are also photons who get carried away and fall into the proton trap,Just like Hou Baolin's cross talk, two drunks compete to climb the flashlight beam, so that they can never get out, and they are still playing there when the sun is destroyed.
Most of the photons that are not obsessed with "playing" finally reach the surface of the sun and are finally released. They run like wild horses and radiate energy in all directions of space at a speed of about 300,000 km per second. Our earth has received 1/2.2 billion of the entire sun’s energy without hesitation, and the energy obtained per second is about 1.77*10^17J, which is equivalent to about 50 billion kilowatt-hours of electricity, which is the total power generation of 10 million Three Gorges Dams It is also equivalent to the energy of exploding more than 3,000 Hiroshima atomic bombs per second.
And the sunlight we bask in every day, although it only takes more than 8 minutes from the surface of the sun to us, but the age of these photons is tens of thousands or even hundreds of thousands to millions of years old, so cherish it.
This is the process of solar nuclear fusion and the way of energy transfer, as well as the reason why it can remain unchanged for 10 billion years. I wonder if you are satisfied with this answer? Comments and discussions are welcome, thanks for reading. The original copyright of
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