Origins and Natures of Inflation, Dark Matter and Dark Energy, 2nd Edition

One of the most significant investigated issues in modern physics and cosmology is the origins of the field that gives rise to inflation, dark matter, and dark energy. It is strongly expected that primordial gravitational waves will be detected in near-future observations, revealing the energy scale of inflation in the early universe. In addition, there are two representative origins of dark matter: new particles in high-energy physics beyond the standard model, and astrophysical objects. Moreover, there are two main approaches that have been proposed to explore the true nature of dark energy leading to the late-time accelerated expansion of the universe. First, one can introduce some unknown energy component, called dark energy with its negative pressure, in general relativity. Second, one may extend the theory of gravity from general relativity at a cosmological scale; namely, dark energy may have a geometrical origin. The main purpose of this Special Issue is to clarify the origins and true nature of inflation, dark matter, and dark energy. We take both phenomenological methods and more fundamental physics such as higher-dimensional theories of gravity, quantum gravity, quantum cosmology, physics in the early universe, quantum field theories and gauge field theories in curved spacetime, string theories, brane world models, and the holographic principle. This Special Issue on inflation, dark matter, dark energy, and the relevant foundations of modern physics is expected to be useful and helpful for future studies.