This book takes us on a scientific journey to explore the physical universe, made up of stars and galaxies scattered throughout the vast cosmos and constantly expanding. This boundless universe is expanding endlessly, raising significant questions about its mysteries and how we can understand the nature of this expansion. The author focuses in this work on the concept of the "cosmological constant," which is the cornerstone of this profound research, as it is considered the hidden force driving the expansion of the universe. This constant is the most mysterious element in this context, and despite the difficulties we may face in understanding it, the author strives to reach new conclusions that shed light on this mystery. This topic is of particular importance because it meets at the intersection of a group of important sciences: astronomy, the theory of relativity, and wave mechanics. Any progress in understanding this cosmological constant will have direct implications for all three fields, making research on this topic of great scientific value. Although the book addresses some difficult concepts, the writing style aims to simplify the complex without compromising the depth of the subject.