Physical science is traditionally defined as the natural science doing the systematic study of the inorganic world, as being completed with the life science of biology doing the systematic study of the organic world.
Its subject is treating of the general properties of matter as a whole, its composition and structure, properties and states, energy and force-relations to formulate the first laws of behavior of the universe and nature basing on natural ontology and mathematics, as divided among four interrelated branches:
Astronomy
Physics
Chemistry
the Earth science
Astronomy
Astronomy, including astrophysics and cosmology, studies the entire universe beyond the Earth, including the universe’s structure and evolution, its cosmic objects (as stars, galaxies, planets, moons, asteroids, comets and nebulae) and their physical processes (as supernovae explosions, gamma ray bursts, and cosmic microwave background radiation, etc.), and how the Earth relates to interactions with the solar system.
Chemistry
Chemistry treats of the structure, composition and properties of substances and all possible changes, transformations or reactions they undergo, being about the properties and reactions of molecules. It is about the interactions of substances through chemical reactions to form different substances, including analytical chemistry, inorganic chemistry, organic chemistry, biochemistry, polymer chemistry, physical chemistry, and industrial chemistry.
The Earth science
Earth science is dealing with planet Earth, how the natural environment (ecosphere of geosphere and biosphere or Earth ecosystem) works and evolves, including the study of the atmosphere, hydrosphere, lithosphere, and biosphere, involving atmospheric science and environmental science, geology and geography, geoinformatics, glaciology, oceanography and soil science.
Physics
The core of physical science, physics, deals with the structure of the matter and the interactions of the fundamental constituents of the universe, including all the hypothetical constructs like as “dark energy”, “dark matter”, or “dark force”. It is the science that treats of matter and energy, forces and interactions and their regularities and laws governing the reciprocal interplay while being tested and proved by analysis and observation, control and measurement.