The questions you are asking touch upon some of the deepest mysteries of the universe, and they are topics that have been explored by scientists, philosophers, and theologians for centuries. While our understanding of the universe has grown over time, there are still many unanswered questions.
Size of the Universe: The universe appears vast and expansive because of its immense scale. It contains billions of galaxies, each with billions of stars, and is constantly expanding. The exact reasons for its size and vastness are not fully known. The current scientific understanding suggests that the universe underwent a rapid expansion known as the Big Bang, which started from a highly compressed and hot state. This expansion is thought to have occurred about 13.8 billion years ago and has resulted in the large-scale structure of the universe we observe today.
Existence of the Universe: The question of why the universe exists is a profound philosophical and scientific inquiry. Scientists have proposed various hypotheses and theories to explain the origin of the universe, such as inflationary cosmology and the multiverse hypothesis. These theories attempt to provide explanations based on scientific principles and observations, but the ultimate cause or reason for the existence of the universe remains a subject of exploration and debate.
Absence of Nothingness: The concept of "nothingness" is complex and can have different interpretations. In the context of the universe, the absence of everything, including space, time, and matter, is a challenging concept to grasp. From a scientific standpoint, our current understanding suggests that the universe emerged from a singularity, a point of extremely high density and energy. The laws of physics as we know them may not apply in such extreme conditions, making it difficult to reason about absolute nothingness.
It's important to recognize that these questions probe the boundaries of human knowledge and understanding. Scientists continue to investigate and develop theories to explain the origin, structure, and nature of the universe, but definitive answers to these profound questions may remain elusive for now. Philosophical and metaphysical perspectives also offer alternative ways of contemplating these inquiries.