Quantum gravity is a very important research topic in theoretical physics because it is believed to bridge quantum mechanics and Einstein's theory of general relativity. This may be true, but quantum gravity is important to basic science primarily because it would show how gravity works on an extremely small scale of spacetime, the quantum level. This work presents many new discoveries that reveal the nature of gravity at the quantum level. Albert Einstein described how gravity works on the macro- and mega-level (i.e. the level of planets and galaxies), but not on the quantum level. In order to understand gravity at the quantum level, it is first necessary to know Einstein's theory of general relativity, with which this work begins. In this paper, Albert Einstein's theory of general relativity has been presented and derived as simply as possible, which means that all irrelevant aspects of general relativity have been omitted. Modern theoretical physics tries to simplify existing theories as much as possible, eliminating all irrelevant information. General relativity can be mathematically extremely complex and a very bulky physical theory, but in this work it is presented and also derived in the most direct and simple way that has not been done anywhere and ever before. This is necessary in particular for understanding quantum gravity.Another comprehensive topic is the physics of wormholes. The physical and mathematical interpretation of wormholes has actually been known for about a hundred years, but their technical creation has not been possible until now. However, in this work, apart from the nature of the wormhole, its technical feasibility is also shown, which has not been presented before. In particular, one specific part of the technology for creating wormholes (the outer part of the machine) is described, which is currently being processed by the United States Patent and Trademark Office ( in 2023 – 2024 ). Thus, the inventor of such technology is licensed by the USPTO. One of the biggest obstacles to the technical creation of wormholes was the production of the necessary energy, but the new discoveries presented in this work show that this is not necessary. The key to the creation of wormholes lies in the changes or creation of energy fields that occur exactly at the speed of light. Physical states that change or arise at the speed of light are also accompanied by the emergence of abstract geometric surfaces with time and space curved to infinity. The actual creation of wormholes is crucial to humanity's plans for the future. They would be practically indispensable for, for example, space travel to great distances, and wormholes would also allow people to travel in time to the past and the future. Time travel could be used in the study of human history and would be a very good tool for accurate weather forecasting, for example. For a long time, wormholes were considered the realm of science fiction and fantasy literature, and in some cases even pseudoscience. However, new discoveries concerning the possibility of their creation, which are thoroughly presented in this work, make the existence of wormholes a tangible reality.This work is primarily aimed at an academic audience, such as students, graduate students, lecturers, researchers, but also interested parties, industrialists and even managers of technology companies and organizations. This work requires the readers to have university-level knowledge of theoretical physics and to a lesser extent of engineering. This work is a part of a larger research work, the content of which is the development of the physical theory of time travel and its technology. References concerning it are also presented in this work.