In optics, the corpuscular theory of light states that light is made up of small discrete particles called "corpuscles" (little particles) which travel in a straight line with a finite velocity and possess impetus. This was based on an alternate description of atomism of the time period.
Isaac Newton laid the foundations for this theory through his work in optics. This early conception of the particle theory of light was an early forerunner to the modern understanding of the photon. This theory came to dominate the conceptions of light in the eighteenth century, displacing the previously prominent vibration theories, where light was viewed as 'pressure' of the medium between the source and the receiver, first championed by René Descartes, and later in a more refined form by Christiaan Huygens. It would fall out of the spotlight in the early nineteenth century, as the wave theory of light amassed new experimental evidence.
Mechanical philosophical
In the early 17th century, natural philosophers began to develop new ways to understand nature gradually replacing Aristotelianism, which had been for centuries the dominant scientific theory, during the process known as the Scientific Revolution.
Various European philosophers adopted what came to be known as mechanical philosophy sometime between around 1610 to 1650, which described the universe and its contents as a kind of large-scale mechanism, a philosophy that explained the universe is made with matter and motion.
This mechanical philosophy was based on Epicureanism, and the work of Leucippus and his pupil Democritus and their atomism, in which everything in the universe, including a person's body, mind, soul and even thoughts, was made of atoms; very small particles of moving matter. During the early part of the 17th century, the atomistic portion of mechanical philosophy was largely developed by Gassendi, René Descartes and other atomists.
Corpuscular theories
Corpuscular theories, or corpuscularianism, are similar to the theories of atomism, except that in atomism the atoms were supposed to be indivisible, whereas corpuscles could in principle be divided.
Corpuscles are single, infinitesimally small, particles that have shape, size, color, and other physical properties that alter their functions and effects in phenomena in the mechanical and biological sciences. This later led to the modern idea that compounds have secondary properties different from the elements of those compounds.
Gassendi asserts that corpuscles are particles that carry other substances or substances and are of different types. These corpuscles are also emissions from various sources such as solar entities, animals, or plants. Robert Boyle was a strong proponent of corpuscularianism and used the theory to exemplify the differences between a vacuum and a plenum, by which he aimed to further support his mechanical philosophy and overall atomist theory.
About a half-century after Gassendi, Isaac Newton used existing corpuscular theories to develop his particle theory of the physics of light.
