If our aircraft probe wants to fly into space, fly at a higher speed, and have stronger space bearing capacity, it needs knowledge of physics, progress of fuel technology and power system, and progress of various specific propulsion devices, but these propulsion devices are realistic, just like branches of a tree, which are really useful, but without the support of trunk, these branches cannot become reality, so he needs enough useful theoretical knowledge.
The development of mathematics is. Look at people's needs, because calculus can be invented. Newton wanted to study the motion state of objects, but he couldn't find a gradual change to express the change of this state, so he invented calculus, which laid the foundation for advanced mathematics, because another name of advanced mathematics is calculus, which is mainly based on calculus. Of course, some other mathematics-related theories, such as linear algebra and theory of viewing, are also applied in real life, but most of them are based on advanced mathematics and need to be used as the basis in various examinations and theoretical research.
To transform science and technology into productive forces, there must be strong theoretical support. Theory is inseparable from the basic things. If we want to go further and fly out of the solar system and the Milky Way, we must have strong enough equipment to support us. Humans can't reach that level on their own, so we must understand some theories, or put it another way, some laws that existing humans can't understand, so as to do what we can't do now.