One of my favorite physics experiments was conducted by Thomas Young (1773-1829) when he demonstrated that light consists of waves by showing that the distribution of brightness by interfering beams could be explained by the additive and subtractive interference of the wavefronts. Young's experiment, performed in the early 1800s, played a vital role in the acceptance of the wave theory of light, defeating Isaac Newton's corpuscular theory which had been the accepted model of light propagation at that time. Although, a later observation by Heinrich Hertz (1857-1894) demonstrated that under different circumstances, the photoelectric effect can cause light to behave as if it is composed of discrete particles. These seemingly contradictory discoveries made it necessary to go beyond classical physics and eventually consider the quantum nature of light.
One of my favorite physics experiments was conducted by Thomas Young (1773-1829) when he demonstrated that light consists of waves by showing that the distribution of brightness by interfering beams could be explained by the additive and subtractive interference of the wavefronts. Young's experiment, performed in the early 1800s, played a vital role in the acceptance of the wave theory of light, defeating Isaac Newton's corpuscular theory which had been the accepted model of light propagation at that time. Although, a later observation by Heinrich Hertz (1857-1894) demonstrated that under different circumstances, the photoelectric effect can cause light to behave as if it is composed of discrete particles. These seemingly contradictory discoveries made it necessary to go beyond classical physics and eventually consider the quantum nature of light.
The double-slit experiment in quantum mechanics is an experiment devised by physicist Thomas Young. It shows that light has both a wave nature or characteristic and a particle nature or characteristic, and that these natures are inseparable. So light is said to have wave–particle duality rather than be only a wave or only a particle. The same is true of electrons and other quantum particles. Although Christiaan Huygens thought that light was a wave, Isaac Newton did not. Newton felt that there were other explanations for color, and for the interference and diffraction effects that were observable at the time. Owing to Newton’s tremendous stature, his view generally prevailed. The fact that Huygens’s principle worked was not considered evidence that was direct enough to prove that light is a wave. The acceptance of the wave character of light came many years later when, in 1801, the English physicist and physician Thomas Young (1773–1829) did his now-classic double slit experiment
The evolution of light theories began with Isaac Newton's corpuscular model, which explained reflection and refraction but could not account for diffraction and interference. In contrast, Christiaan Huygens proposed a wave theory, explaining light's behavior through an ether-based medium, supported by his principle that each point in a wavefront acts as a secondary source. This idea was experimentally supported in the early nineteenth century when Thomas Young's double-slit experiment revealed an interference pattern, affirming light's wave nature. Later, James Clerk Maxwell unified electricity and magnetism, establishing light as an electromagnetic wave and extending the electromagnetic spectrum beyond visible light. In the twentieth century, Einstein's photoelectric effect introduced the concept of wave-particle duality, demonstrating that light behaves as discrete photons. Soon after, Louis de Broglie extended the idea of wave-particle duality to matter, a prediction confirmed in 1927 when Clinton Davisson and Lester Germer observed electron diffraction from a crystal and, independently, G.P. Thomson demonstrated electron diffraction through thin films, both proving that electrons also exhibit wave-like properties. This concept was dramatically visualized by Claus Jonsson's 1961 electron double-slit experiment. Recently, the ALICE collaboration observed quantum interference patterns at the femtometer scale in ultra-relativistic nuclear collisions, pushing quantum interference studies to new frontiers.
In the process of exploring the essence of light, Newton initially agreed with the particle interpretation of light while Huygens argued for the wave theory. Hence, these two theories had been disputed in Newton's time. In the beginning people accepted the particle theory, but after Thomas Young's experiment and Augustin Jean Fresnel's experiment, people began to accept the wave theory. Until Einstein proposed the quanta concept, which was later called photon, and, even later, De Broglie proposed the wave nature of matter, subsequently, people began using particle-wave duality to explicate all phenomena in micro world. Thus here appears a paradox: how can one particle exist in two forms? To solve this enigma, I have done some experiments; discover that moving photons create force; this effect reveal the phenomenon of light wave property - the inference fringes is caused by force which moving photons produced. The essence of light is particle but not particle-wave duality.
In the process of exploring the essence of light, Newton initially agreed with the particle interpretation of light while Huygens argued for the wave theory. Hence, these two theories had been disputed in Newton’s time. In the beginning people accepted the particle theory, but after Thomas Young’s experiment and Augustin Jean Fresnel’s experiment, people began to accept the wave theory. Until Einstein proposed the quanta concept, which was later called photon, and, even later, De Broglie proposed the wave nature of matter, subsequently, people began using particle-wave duality to explicate all phenomena in micro world. Thus here appears a paradox: how can one particle exist in two forms? To solve this enigma, I have done some experiments; discover that moving photons create force; this effect reveal the phenomenon of light wave property - the inference fringes is caused by force which moving photons produced. The essence of light is particle but not particle-wave duality.
Quantum theory is a mathematical formalism that allows physicists to predict the probability of observing different outcomes in experiments on sub-atomic systems. It has been tested more rigorously than any theory in science, and has never been wrong. However, strictly speaking it does not “explain” the behavior of sub-atomic systems, since it does not propose a mechanism to account for it. It tells us that they will behave in certain ways, but not why . Thus, quantum mechanics is not a theory in the sense familiar to social scientists, namely a body of laws that explains some part of reality. The explanatory question is the subject of the interpretive debates that surround the theory, not of the theory per se. That said, the literature routinely refers to quantum mechanics as a theory, and I shall use the terms interchangeably below. A common way to introduce quantum theory is through some of the key experiments that have confirmed its predictions. In this chapter I describe three of the most well-known: the Two-Slit Experiment, the Bell Experiments, and the Delayed-Choice Experiment. While painting the same overall picture, each reveals distinct features of the quantum realm. While their interpretation is contested, here I will do my best to present just the theory's findings, saving interpretive questions for later. The Two-Slit Experiment This experiment actually had its origins long before the quantum revolution. One of the most controversial questions in classical physics was whether light was made of particles or waves. In keeping with his atomistic worldview, Newton favored the particle or “corpuscular” theory of light, which was the majority view among physicists through the eighteenth century. However, in 1801 Thomas Young performed an experiment that seemed to prove conclusively that the wave theory was correct. In his experiment, Young set up a light source behind an opaque screen with one small opening or slit, through which the light passed in a concentrated beam.
Science, as it is generally described at school, starts with experimental data. Scientists then have to find some hypothesis which explains these results. Using this hypothesis, a prediction is made about what might happen in a slightly different experiment. The double-slit experiment is a modified version of the setup first used by Thomas Young in 1801. Young’s version is a classic experiment that, at the time, seemed to have settled the dispute between wave and particle views of light decisively in favour of waves. The idea that particles might display some wavelike properties dates to the mid-1920s when a young PhD student called Louis De Broglie was thinking about the dual wave/particle nature of light. A quantum mechanical description of the double-slit experiment must involve a set of amplitudes governing the passage of an electron through the slits to the far detector.