Changes

===The Modern Era===

===The Modern Era===

By the close of the 19th century, the study of physics was widely thought to be essentially complete, with the exception of only a few "loose ends"--minor unsolved problems to be dealt with.  As a solution to the so-called [[ultraviolet catastrophe]] problem, which involved light emission from [[blackbody|hot, dark objects]], Max Planck proposed in 1900 that the sources of light could be represented by small individual oscillators.  Planck referred to the individual oscillators as ''quanta''.  At the time, Planck did not regard his finding as revolutionary; he thought that he was merely "fudging" the mathematics to arrive at a better solution.  However, in 1905, [[Albert Einstein]] published a solution to the [[photoelectric effect]] problem:  light could be thought of as being composed of very small, discrete packets (quanta), as opposed to the classical representation of light as a collection of waves.  The discoveries of Planck and Einstein ushered in an entirely new era in physics.  By the end of the 1930s, quantum mechanics--the name given to the new theory that applied to matter and energy on atomic scales--was well-established.  Other physicists began applying the theory to more specific aspects of physics, resulting in quantum mechanical descriptions of electricity and magnetism, the [[weak force|weak]] and [[strong force|strong]] atomic forces, [[condensed matter]] physics, and many other areas.  

By the close of the 19th century, the study of physics was widely thought to be essentially complete, with the exception of only a few "loose ends"--minor unsolved problems to be dealt with.  As a solution to the so-called [[ultraviolet catastrophe]] problem, which involved light emission from [[black body|hot, dark objects]], Max Planck proposed in 1900 that the sources of light could be represented by small individual oscillators.  Planck referred to the individual oscillators as ''quanta''.  At the time, Planck did not regard his finding as revolutionary; he thought that he was merely "fudging" the mathematics to arrive at a better solution.  However, in 1905, [[Albert Einstein]] published a solution to the [[photoelectric effect]] problem:  light could be thought of as being composed of very small, discrete packets (quanta), as opposed to the classical representation of light as a collection of waves.  The discoveries of Planck and Einstein ushered in an entirely new era in physics.  By the end of the 1930s, quantum mechanics--the name given to the new theory that applied to matter and energy on atomic scales--was well-established.  Other physicists began applying the theory to more specific aspects of physics, resulting in quantum mechanical descriptions of electricity and magnetism, the [[weak force|weak]] and [[strong force|strong]] atomic forces, [[condensed matter]] physics, and many other areas.  

In another 1905 publication, Einstein announced his discovery of what became known as the [[special relativity|special theory of relativity]], which revolutionized the way physicists thought about [[space]] and [[time]].  Einstein later extended the concept to non-inertial [[reference frames]], which resulted in the [[general relativity|general theory of relativity]], an improved description of [[gravity|gravitational]] interactions, which was published in 1915.

In another 1905 publication, Einstein announced his discovery of what became known as the [[special relativity|special theory of relativity]], which revolutionized the way physicists thought about [[space]] and [[time]].  Einstein later extended the concept to non-inertial [[reference frames]], which resulted in the [[general relativity|general theory of relativity]], an improved description of [[gravity|gravitational]] interactions, which was published in 1915.