To answer this question, we must first answer the source of matter. Primitive particles (I don't know what they are called) are distributed in space. Because of the primitive existence, the spatial distance between two particles is close. Because particles are matter and have the properties of matter, there is a weak gravitational force around them. Under this weak gravitational force, the two original particles gradually approached each other and eventually formed a larger particle combination. Because of the combination of particles, the range and intensity of gravity around the combination are expanded and enhanced. In infinite time and space, this combination effect began to develop, forming the original planet, which exploded due to the infinite increase of internal pressure. This explosion (that is, the first push) led to the existence order of primitive particles in the previous space, resulting in the present universe. Let's talk about the source of energy first: the initial formation of the earth was also formed by the accumulation of meteorites. As long as we analyze the falling process of one of the meteorites, the source of energy will be solved. Meteorite roams freely in the infinite space of the earth. When it approaches any planet, gravity acts on it, making it move to this planet in a tangent way, and further gaining kinetic energy in the space. When the kinetic energy is greater than the binding force of that planet, the meteorite just changes direction and flies to another planet. When the kinetic energy is less than the binding force of the planet, the meteorite will land on that planet. When the meteorite is "infinitely far away" from the earth, the gravitational effect of the earth on the meteorite is zero. When the meteorite approaches the earth, the gravity of the earth on the meteorite is a process from scratch. At this time, the potential energy of the meteorite relative to the earth is also a process from "nothing" to existence, because the concept of potential energy is attached to the concept of force, and the force can be from scratch, so the potential energy can also be from scratch, but the potential energy at this time is stored potential energy or dark potential energy. When the stored potential energy value of meteorites is greater than the inertia value of meteorites, meteorites begin to fall to the earth. At this time, the meteorite has been captured by the earth. At this time, the potential energy of meteorites is continuously transformed into kinetic energy, and finally into work and heat, which becomes a part of the energy inside the earth. It can be seen from this process that the internal energy of the earth comes from the combination of countless meteorites and meteorite dust, which is the source of energy. When this combination process is over, energy will naturally be conserved forever, which is the source of energy conservation.