Throughout history, humanity has thought about the nature of such a phenomenon as light. From ancient times to the present day, ideas about him have changed and improved. The most popular hypotheses are that light is a particle or wave. A section of modern science that studies the nature and behavior of light is called optics.
The history of the development of ideas about the world
According to the ideas of ancient Greek philosophers, for example, Aristotle, light is the rays emanating from the human eye. Through ether, a transparent substance that fills space, these rays spread, allowing a person to see objects.
Another philosopher, Plato, suggested that the sun is the source of light on Earth.
The philosopher and mathematician Pythagoras believed that tiny particles fly out of objects. Once in the human eye, they give us an idea of the appearance of these objects.
Despite the apparent naivety, these hypotheses laid the foundation for the further development of thought.
So, in the XVII century, the German scientist Johannes Kepler expressed a theory close to the ideas of Plato and Pythagoras. In his opinion, light is a particle, or more precisely, a stream of particles propagating from some source.
Newton's corpuscular hypothesis
Scientist Isaac Newton put forward a theory that combined to some extent conflicting ideas about this phenomenon.
According to Newton's hypothesis, light is a particle whose velocity of movement is very high. The corpuscles spread in a homogeneous environment, moving uniformly and rectilinearly from the light source. If a stream of these particles enters the eye, then the person observes its source.
According to the scientist, the corpuscles were uneven in size, giving sensations of various colors. For example, large particles contribute to the fact that a person sees a red color. He argued the phenomena of reflection of a stream of light as a rebound of particles from a solid barrier.
The scientist explained the white color by the combination of all the colors of the spectrum. On this conclusion his theory of dispersion is built - a phenomenon discovered by him in 1666.
Newton's hypotheses are widely recognized among his contemporaries, explaining many optical phenomena.
Huygens Wave Theory
Another scholar of the same time, Christian Huygens, did not agree that light is a particle. He put forward the wave hypothesis of the nature of light.
Huygens believed that the entire space between objects and in the objects themselves is filled with ether, and light radiation is impulses, waves propagating in this ether. Each section of the ether to which the light wave reaches becomes a source of so-called secondary waves. Experiments on the interference and diffraction of light have confirmed the possibility of a wave explanation of the nature of light.
Huygens's theory did not receive much recognition in his time, since most scientists were inclined to consider light as a particle. However, it was subsequently adopted and finalized by many scientists, for example, Jung and Fresnel.
Further development of representations
The question of what light is in physics continued to occupy the minds of scientists. In the 19th century, James Clerk Maxwell developed a theory according to which light radiation is high-frequency electromagnetic waves. His ideas were based on the fact that the speed of light in vacuum is equal to the speed of electromagnetic waves.
In 1900, Max Planck introduced into science the term "quantum", which translates as "portion", "small amount". According to Planck, electromagnetic radiation does not occur continuously, but in batches, by quanta.
These representations were developed by Albert Einstein. He suggested that light is not only emitted, but also absorbed and spread by particles. To use them, he used the word "photons" (a term first coined by Gilbert Lewis).
Wave-particle duality
A modern explanation of the nature of light lies in the concept of wave-particle duality. The essence of this phenomenon is that matter can exhibit the properties of both waves and particles. Light is an example of such matter. The studies of scientists who came to seemingly opposite opinions confirm the dual nature of light. At the same time, light is a particle and a wave. The severity of each of these properties depends on the specific physical conditions. In certain cases, light exhibits the properties of an electromagnetic wave, confirming the wave theory of its origin, in other cases, light is a stream of corpuscles (photons). This suggests that light is a particle.
Light became the first matter in the history of physics, which recognized the presence of wave-particle duality. Later this property was discovered in a number of matters, for example, wave behavior is observed in molecules and nucleons.
Summing up, we can say that light is a unique phenomenon, the history of the development of ideas about which has more than two thousand years. According to the modern understanding of this phenomenon, light has a dual nature, manifesting the properties of both waves and particles.