The general chemical reaction on the earth is much more frequent than this nuclear reaction, and it is much more difficult to start, stop and continue this nuclear reaction. Therefore, before the end of the19th century, people did not pay enough attention to it. In addition, there is a real reason that the radioactive reaction is very slow, so the energy released in a specific time is also very small, and the occurrence of nuclear reaction in nature is closely related to radioactive activities.
In nuclear reaction, the total energy released by a certain mass of substances is much greater than that released by the same mass of substances in chemical reaction. Therefore, although the kinetic energy generated by the chemical reaction caused by gradual contraction is not enough to support the life time of the sun, nuclear energy can, but scientists need to find out the corresponding types of nuclear reactions.
The spontaneous nuclear reaction on the earth contains a large number of uranium atoms and thorium atoms. In the process of radiation reaction, some uranium atoms and thorium atoms are broken into pieces, thus generating energy. If the mass of uranium and thorium atoms is reduced by about half during fission, more energy will be generated. But even so, the energy generated in the above reaction process is not enough to maintain the life course of the sun, and the sun itself contains only a small amount of atoms.
For atoms of medium size, they contain less energy. In the ordinary radioactive reaction or fission process, atoms are like landslides. When atoms with larger atomic weights split into smaller atoms, energy is released. The same phenomenon also occurs in the process of small mass atoms polymerizing into heavy atoms. It is assumed that hydrogen atoms (the lightest atoms) can be polymerized into helium atoms (the second lightest atoms). In this process, the heat generated by hydrogen atoms with a given weight is much greater than that generated by uranium atoms with the same weight.
It is known that 75% of the sun's weight comes from hydrogen and the remaining 25% comes from helium. Hydrogen in the sun provides a lot of energy for the sun during polymerization, and the rich hydrogen content in the sun will make this process last 1 100 million years.
In addition, there is a thorny issue in the field of nuclear reaction. That is to say, for atoms with large atomic weight, their state is more unstable, that is to say, such atoms are in the critical state of reaction, and under the impetus of minimal force, they will decay, and sometimes they may occur completely spontaneously. Therefore, the fission of atoms should be extremely easy to occur under appropriate conditions. The nuclei of hydrogen atoms are arranged so closely that they have the possibility of fusion. On the other hand, because the external electron activity in hydrogen atoms is similar to the shell in the macro world, this fusion reaction is difficult to occur under general conditions. When two hydrogen atoms collide, their external electrons will repel each other during the collision, and it is absolutely impossible to get close to each other.
However, this phenomenon only applies to the conditions on earth. The ultra-high temperature on the sun is enough to break the chemical bonds between hydrogen atoms and promote the constant movement of the nuclei inside the atoms. The strong atmospheric pressure of the sun will make hydrogen atoms collide closely, and its ultra-high temperature will make hydrogen atoms move much faster than oxygen atoms on earth. All these phenomena will be accompanied by great force, which makes the polymerization of hydrogen atoms possible.
German-American physicist Hans Albright Bess devoted himself to the study of hydrogen fusion and conducted nuclear reaction experiments under laboratory conditions. At the same time, according to this experiment, he made an approximate judgment on the temperature and pressure that the sun center should have for the same reaction. 1938, Beth made a plan to study the nuclear reaction that provides the necessary energy for the existence of the sun. So far, his related theories are still authoritative. At this point, Helmholtz's question finally got the correct answer after a century.