Matter

Matter is a substantial substance that makes up the visible cosmos and, along with energy, is the foundation for all objective occurrences.

Matter is made up of elementary particles known as quarks and leptons, which is the class of elementary particles that contains electrons, at the most fundamental level. Quarks combine to generate protons and neutrons, which interact with electrons to form atoms of periodic table elements like hydrogen, oxygen, and iron. Atoms can be combined to form molecules, such as H2O, the water molecule. The bulk matter of everyday life is made up of large clusters of atoms or molecules.

Solid, liquid, and gas are the three most common forms, or states, of matter. A substance can be changed from one condition to another by heating and cooling it. The tiniest units of a substance, called molecules, behave differently when it changes state. The material's molecules, on the other hand, do not break apart and generate a new material. They haven't changed. A state change is a change that can be reversed.

Matter can exist in a variety of states depending on temperature and other factors. Gold, for example, is a solid, water is a liquid, and nitrogen is a gas at ordinary temperatures, as characterized by certain characteristics: solids retain their shape, liquids take on the shape of the container in which they are held, and gases fill a complete container. These states can be divided into subcategories. Solids, for example, can be classified as crystalline or amorphous, or as metallic, ionic, covalent, or molecular solids, depending on the types of bonds that hold the constituent atoms together.

Plasmas, which are ionized gases at very high temperatures; foams, which mix aspects of liquids and solids; and clusters, which are groupings of small numbers of atoms or molecules that exhibit both atomic-level and bulklike properties, are examples of less-clearly defined forms of matter.

However, all matter of any kind shares the fundamental attribute of inertia, which prohibits a material body from responding instantly to attempts to change its state of rest or motion, as defined in Isaac Newton's three laws of motion. The mass of a body is a measure of its resistance to change; propelling a big ocean liner is far more difficult than pedaling a bicycle. Another universal attribute is gravitational mass, which states that every physical entity in the universe attracts every other physical entity, as established by Newton and later refined into a new conceptual form by Albert Einstein.

Although Newton's core concepts about matter may be traced back to Aristotle's natural philosophy, it wasn't until the early twentieth century that more understanding of matter, as well as new puzzles, emerged. Einstein's special relativity theory, published in 1905, demonstrates that matter and energy may be changed into one another using the famous equation E = mc2, where E represents energy, m represents mass, and c represents the speed of light. For example, during nuclear fission, the nucleus of a heavy element such as uranium breaks into two fragments of smaller total mass, with the mass difference released as energy.

In 1916, Einstein published his general theory of relativity, which takes as its core assumption the empirically established equivalence of inertial and gravitational mass and explains how gravity arises from the distortions that matter imposes into the surrounding space-time continuum.

Quantum mechanics, which has its roots in Max Planck's description of the qualities of electromagnetic radiation generated by a heated body in 1900, further complicates the concept of matter. Elementary particles, according to the quantum interpretation, act both like tiny balls and like waves that expand out in space, posing an apparent paradox that has yet to be fully addressed. Astronomical measurements, which began in the 1930s and suggest that a huge portion of the cosmos is made up of "dark matter," add to the intricacy of the meaning of matter. This invisible substance has no effect on light and can only be discovered by its gravitational effects. Its level of specificity has yet to be determined.

On the other hand, physicists may be on the verge of explaining the origin of mass through the current search for a unified field theory, which would combine three of the four types of interactions between elementary particles (the strong force, the weak force, and the electromagnetic force, excluding only gravity) into a single conceptual framework.

Although a fully satisfactory grand unified theory has yet to be derived, one component, Sheldon Glashow, Abdus Salam, and Steven Weinberg's electroweak theory, predicted that an elementary subatomic particle known as the Higgs boson imparts mass to all known elementary particles, for which they shared the 1979 Nobel Prize in Physics. 

In 2012, scientists reported the discovery of the Higgs boson after years of research using the most powerful particle accelerators available.