Physical Sciences

Physical Science is the study of non-living systems.

Astronomy
Astronomy is the science of celestial objects and phenomena that exist outside the Earth’s atmosphere.  It studies and formulates models of stars (plasma ball), planets (bodies that orbit stars), comets (small solar system body), galaxies (system of stars, gas) and the cosmos (the Universe).

Chemistry
Chemistry studies matter at the atomic and molecular state to learn it properties, structure, reactions and interactions.  It is known as the ‘central science’ since it connects physics with other natural sciences such as astronomy, geology and biology.

Earth Science
Earth Science (geoscience) includes many disciplines that are related to study of the planet Earth:  atmospheric science, geology, geophysics, hydrology, meteorology, physical geography, oceanography and soil science.

Physics
Physics is the study of matter, motion, energy and force.  It includes the study of mechanics, fluids, thermodynamics (heat), vibrations, light, electricity & magnetism, relativity and quanta.  Physics relies heavily on mathematics as framework for the formulation and quantification of principles.  Physics Timeline.

Materials Science
Materials science studies material structures at atomic or molecular scales to determine their properties.  It incorporates applied physics and chemistry.  Material science is so pervasive in human evolution, historians even have time periods name after important materials: Stone Age, Bronze Age and the Steel Age.  Up until the mid 20th century, materials science departments were named metallurgy departments.  The field has since broadened to include ceramics, polymers, semiconductors, magnetic materials and medical implant materials. The forefront of material science is nano science and nanotechnology, where the nanometer world is so small, quantum mechanical effects become important.  Nanotechnology is the ability to understand, control and manipulate matter at the level of individual atoms and molecules, as well as at the “supramolecular” level involving clusters of molecules. It is a revolutionary technology that has the potential to create a broad technology platform from industry, medicine and other fields. Nanotechnology is one those interesting natural sciences that has huge implications in the social sciences – irresponsible regulation of scientific studies can lead to very real issues such as health and environmental effects of nanosized particles (notwithstanding the ‘Hollywood’ nanohype of predator ‘nanobots’ as portrayed in Michael Crichton's science fiction novel Prey).

Significant Physical Science Theories

Astronomy:  Big Bang Theory
Assumes that the universe began from a singular state of infinite density and expanding from an explosive moment of creation.  Fred Hoyle coined the term Big Bang.  According to the Big Bang, the universe was created sometime between 10-20 billion years ago from a cosmic explosion that hurled matter in all directions.

Geology:  Plate Tectonic Theory
Earth is divided into a number of rigid plates floating on a viscous under-layer in the mantle.  Alfred Wegener was the first to propose (1912) that the continents were at one time connected and had drifted apart.  H.H. Hess (1960) has proposed that the new ocean floor was created at the mid-oceanic ridges and that the ocean evolved by seafloor spreading.
Physics: Modern Atomic Theory
The atom is composed of a central nucleus composed of two particles, the neutron and the proton, surrounded by a cloud of extremely small particles called electrons.  Neutrons and protons are composed of smaller particles called quarks.  Currently the atom is described by the mathematics of “state vectors residing in a complex separable Hilbert space”, known as the field of science called Quantum Mechanics.  It is challenging to describe an atom in simplistic terms on the macroscopic level because the physical laws that determine the actual “appearance” of an atom exist only in the ultramicroscopic level described in quantum mechanics.  The physical laws of the macroscopic level do not have meaning at the quantum level.  Any macroscopic description is extremely limited because the scientific laws and principles to not apply at the atomic level.

Physics:  Kinetic Molecular Theory (KMT)
Matter is composed of tiny particles in constant motion.  KMT explains the processes of osmosis, diffusion and the concept of temperature.   It also provides a means of understanding of energy transfer between particles of matter.

Physics:  Theory of Gravity
In general, Newton’s Theory of Gravity describes an attractive force that is 1) universal, 2) always attractive, 3) a long-ranging interaction (gravity can affect objects millions of miles distant from each other).  Modern gravitational theory as developed by Einstein (general relativity) ascribe spacetime curvature instead of a force.  The starting point for general relativity is the equivalence principle, which equates free fall with inertial motion, and describes free-falling inertial objects as being accelerated relative to non-inertial observers on the ground.  In Newtonian physics, no such acceleration can occur unless at least one of the objects is being operated on by a force.  Einstein proposed that spacetime is curved by matter, and that free-falling objects are moving along locally straight paths in curved spacetime.  Einstein discovered the field equations (non-linear, differential) of general relativity, which relate the presence of matter and the curvature of spacetime and are named after him

Physics: Special Relativity
Albert Einstein’s theory of special relativity (1905) showed that energy and matter are different manifestations of the same phenomenon.  There are related by the famous equation E=mc2.

Physics:  Quantum Mechanical Theory
Energy exists in tiny discrete units called quanta.   Classical Maxwell-Newton theory of light describes it as a wave motion, whereas quanta theory describes light as composed of discrete particles (photons). Quantum theory can also show how atomic particles such as electrons have wavelike properties.  Quantum theory is the basis of particle physics, modern theoretical chemistry, and the solid-state physics that describes the behavior of the silicon chips used in computers.  Quantum theory and the theory of relativity form the theoretical basis of modern physics.

Physics:  String Theory
All matter is composed of ‘strings’.  The strings themselves are the smallest possible particles, with a length of 10-33 cm, and no width or height.  String can be open or closed.  Closed strings have the shape of circle or oval, and open strings have ends.  A string occupies one single point in space-time at any one time.

Physics: Unified Field Theory

Currently, there are four fundamental forces in nature: 1) electromagnetism, 2)  strong nuclear force, 3) weak nuclear force and 4) gravity.  Einstein felt that there must be a simpler explanation in nature for the interactions between matter than the concept of the four fundamental forces.  He looked for a single, more elegant concept.  Einstein worked for the last twenty years of his life without discovering the elegant explanation he envisioned.   Since his death (1955), continued scientific investigation has unified three of the four forces.  Quantum Gravity (QG) physics is currently attempting to develop scientific models that unify quantum mechanics (describing three of the four known fundamental interactions) with general relativity (describing the fourth, gravity).   Such a ‘Unified Field Theory’ would unify all fundamental interactions and describe all known observable interactions in the universe, at both subatomic and astronomic scales, into a single consistent model.