Corpuscular theory of light

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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.

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.[1]
It would fall out of favor in the early nineteenth century, as the wave theory of light amassed new experimental evidence.

Mechanical philosophy

Main article:
Mechanical philosophy

In the early 17th century, natural philosophers began to develop new ways to understand nature gradually replacing

motion.[2] 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.

Pierre Gassendi's atomist matter theory

The core of Pierre Gassendi's philosophy is his atomist matter theory. In his great work, Syntagma Philosophicum, ("Philosophical Treatise"), published posthumously in 1658, Gassendi tried to explain aspects of matter and natural phenomena of the world in terms of atoms and the void. He took Epicurean atomism and modified it to be compatible with Christian theology, by suggesting several key changes to it:[2]

  1. God exists
  2. God created a finite number of indivisible and moving atoms
  3. God has a continuing divine relationship to creation (of matter)
  4. Humans have free will
  5. The human soul exists
  6. God was not born and will never die (God was always here and will always be)

Gassendi thought that atoms move in an empty space, classically known as the void, which contradicts the Aristotelian view that the universe is fully made of matter. Gassendi also suggests that information gathered by the human senses has a material form, especially in the case of vision.[3]

Corpuscular theories

Corpuscular theories, or

plenum, by which he aimed to further support his mechanical philosophy and overall atomist theory.[3] About a half-century after Gassendi, Isaac Newton used existing corpuscular theories to develop his particle theory of the physics of light.[4]

Isaac Newton

Main article: Isaac Newton

Isaac Newton worked on optics throughout his research career, conducting various experiments and developing hypotheses to explain his results.[5] He dismissed Descartes' theory of light because he rejected Descartes’ understanding of space, which derived from it.[6] With the publication of Opticks in 1704, Newton for the first time took a clear position supporting a corpuscular interpretation, though it would fall on his followers to systemise the theory.[7] In the book, Newton argued that the geometric nature of reflection and refraction of light could only be explained if light were made of particles because waves do not tend to travel in straight lines.

Newton's corpuscular theory was an elaboration of his view of reality as interactions of material points through forces. Note Albert Einstein's description of Newton's conception of physical reality:

[Newton's] physical reality is characterised by concepts of

translation, and the additional concept of force.[8][9]

  1. Every source of light emits large numbers of tiny particles known as corpuscles in a medium surrounding the source.
  2. These corpuscles are perfectly elastic, rigid, and weightless.[10]

Polarization

The fact that light could be

Longitudinal waves
may not be polarised.

End of corpuscular theory

The dominance of Newtonian natural philosophy in the eighteenth century was one of the decisive factors ensuring the prevalence of the corpuscular theory of light.[11] Newtonians maintained that the corpuscles of light were projectiles that travelled from the source to the receiver with a finite speed. In this description, the propagation of light is transportation of matter.

However by the turn of the century, beginning with

interference, and polarization showcased issues with the theory. A wave theory based on Young, Augustin-Jean Fresnel and François Arago's work would materialise in a novel wave theory of light.[12]
To some extent, Newton's corpuscular (particle) theory of light re-emerged in the 20th century, as a light phenomenon is currently explained as particle and wave.

See also

References

  1. ^ Paolo Mancoso, “Accoustics and Optics,” in The Cambridge History of Science Volume 3: Early Modern Science ed. Katharine Park and Lorraine Daston (Cambridge: Cambridge University Press, 2006), 623-626.
  2. ^
    ISBN 978-0801896552
    .
  3. ^ a b plato.stanford.edu Stanford Encyclopedia of Philosophy: Pierre Gassendi. Fisher, Saul. 2009.
  4. ^ virginia.edu – Newton's Particle Theory of Light Lecture notes. Lindgren, Richard A. Research Professor of Physics. The University of Virginia, Department of Physics.
  5. ^ Alan E. Shapiro, “Newton’s Optics,” in The Oxford Handbook of the History of Physics ed. Jed Z. Buchwald and Robert Fox (Oxford: Oxford University Press, 2013).
  6. ^ Olivier Darrigol, A History of Optics: From Greek Antiquity to the Nineteenth Century, (Oxford: Oxford University Press, 2012), 80.
  7. ^ Geoffrey Cantor, Optics after Newton: Theories of Light in Britain and Ireland, 1704-1840 (Manchester: Manchester University Press, 1983), 11-12, 24-26.
  8. ^ Maxwell's Influence on the Development of the Conception of Physical reality (Sonja Bargmann's 1954 Eng. Translation), an appreciation by Albert Einstein, pp. 29–32, The Dynamical Theory of the Electromagnetic Field (1865), James Clerk Maxwell, edited by Thomas F. Torrance (1982); Eugene, Oregon: Wipf and Stock Publishers, 1996
  9. ^ Maxwell's influence on the development of the conception of physical reality , Albert Einstein, in James Clerk Maxwell: A Commemorative Volume 1831-1931 (Cambridge, 1931), pp. 66–73
  10. ^ gutenberg.org Opticks, or, a Treatise of the Reflections, Refractions, Inflections, and Colours of Light. Sir Isaac Newton. 1704. Project Gutenberg ebook released 23 August 2010.
  11. ^ Darrigol, A History of Optics, 164-165.
  12. doi:10.1016/j.crhy.2017.11.005
    .

External links
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