Under the action of the forces of universal gravity, the cloud of interstellar gas, consisting mainly of hydrogen, contracts and heats up, because due to the law of conservation of energy, the potential energy of gas particles in the gravitational field decreases as they approach the center of the cloud, while converting into the internal energy of the gas. If the mass of the cloud is large enough, the temperature and pressure in the center of the cloud reach values at which thermonuclear fusion reactions begin, as a result of which hydrogen is converted into helium.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.