The question ‘is light a ray, a wave or a particle?’ has long fascinated philosophers and has intensified since the concept of the photon first emerged at the beginning of the twentieth century. The pragmatic answer to the question is ‘it depends what you are looking for’ and is really about how best to conceptualise light in particular circumstances. We have already mentioned such distinctions briefly in Chapter 1. This chapter will extend these basic concepts to introduce the material which follows in later chapters.
The question ‘is light a ray, a wave or a particle?’ has long fascinated philosophers and has intensified since the concept of the photon first emerged at the beginning of the twentieth century. The pragmatic answer to the question is ‘it depends what you are looking for’ and is really about how best to conceptualise light in particular circumstances. We have already mentioned such distinctions briefly in Chapter 1. This chapter will extend these basic concepts to introduce the material which follows in later chapters.
Newton thought that light was made up of particles, but then it was discovered, as we have seen here, that it behaves like a wave. Later, however (in the beginning of the twentieth century) it was found that light did indeed sometimes behave like a particle. Historically, the electron, for example, was thought to behave like a particle, and then it was found that in many respects it behaved like a wave. So it really behaves like neither. Now we have given up. We say: “it is like neither.” ere is one lucky break, however-electrons behave like light. e quantum behaviour of atomic objects (electrons, protons, neutron, photons, and so on) is the same for all, they are all ‘particle waves’ or whatever you want to call them.
Have you ever tried to define light? If so, your definition is probably related to vision, the ability to see things. The Merriam-Webster English dictionary defines light as “something that makes vision possible”. However, the definition of the “nature of light” is a complex term already discussed by philosophers of Ancient Greece. In the 17th century, the debate on the matter focused on whether light was a particle or a wave, based on the different properties of light that had been gradually discovered over time. Isaac Newton (1642−1727) was a defender of the corpuscular theory of light, which considered light to be formed by particles, i.e., small pieces of matter, like dust or grains of sand. He was the author of Opticks (1706), the front cover of which appears in Fig. 1.1. Christian Huygens (1629–1695), on the other hand, supported the theory that light is a wave. These are two completely different definitions of the same physical concept. A range of experiments were developed to attempt to clarify this dilemma, but it was only until 1900 when Max Planck (1858-1947) introduced the basis of a theory that would go on to revolutionize scientific thinking, marking the beginning of modern physics: quantum theory. Developed during the 20th century thanks to advances made by scientists such as Niels Bohr, Born, Heisenberg, Schrödinger, Pauli, Dirac, Einstein or de Broglie, quantum theory clarified that light is neither a particle nor a wave, but that it has a dual nature: it behaves like a wave as it spreads but like a particle in its interactions with matter. In this book, we will specify where necessary whether light behaves as a particle or as a wave, although in most cases we refer to rays of light, which always represent the direction of propagation of light.
What is 'the nature of reality’? This thought has occupied the minds of scientists and philosophers since time immemorial. This issue is examined scientifically, that, how the views of scientists and western philosophers have undergone a dramatic change over a period of time. This may then answer whether spacetime is a reality of nature or if it is just a figment of our imagination in which to view this cosmos! The article begins with the thoughts of Democritus, and the other Greek philosophers, continuing with the ideas of Copernicus, Galileo and Kepler. With the thoughts of Bacon, Descartes and Isaac Newton, the rise of the ‘mechanical world view’ later the decline of this view is discussed when the phenomenon in optics, electricity and magnetism could not be explained. Then the concept of ‘field’ was evolved, culminating in ‘Maxwell’s equations of electromagnetic fields’.The beginning of twentieth century saw the evolution of the concepts of ‘relativity’, by Einstein, and the birth of ‘quantum theory’, starting with the idea of ‘quanta’, originated by Planck in 1900. The first three decades of the 20th century saw great breakthroughs in the world of theoretical physics - totally new ideas on ‘the nature of reality’ were being conceived. Large numbers of fundamental particles were discovered in the ensuing years. However, not much progress indeed was made in answering some of the most fundamental questions about the existence of human life and the nature of reality. Some interesting ideas on ‘biocentrism’ have now evolved. Biocentrism, along with the ideas of quantum theory and the concept of consciousness, may answer some of the intricate questions about the nature of reality; these will be discussed at length. These concepts will then be viewed from the perspective of Indic thoughts. The ‘Vedic’ and ‘Upanishadic’ knowledge from Indian scriptures may probably answer even more clearly some of the most intriguing questions about the existence of life and the ‘nature of reality’ itself.Beginning of twentieth century saw the evolution of the concepts of ‘Relativity’, by Einstein, and the birth of ‘Quantum Theory’, starting with the idea of ‘Quanta’, originated by Planck in 1900. The first three decades of 20th century saw the great breakthroughs in the world of theoretical physics. Absolutely new ideas on ‘The Nature of Reality’ were being conceived. Large number of fundamental particles was discovered in the ensuing years. But not much progress indeed took place in answering some of the most fundamental questions on existence of human life and the nature of reality. Some interesting ideas on ‘Biocentrism’ have now evolved. Biocentrism along with the ideas of Quantum Theory and the concept of Consciousness may answer some of the intricate questions on nature of reality; these will be discussed at length. These concepts will then be viewed from perspective of Indic thoughts. The ‘Vedic’ and ‘Upanishadic’ knowledge from Indian scriptures may probably answer even more clearly some of the most intriguing questions on the existence of life and the ‘Nature of Reality’ itself.
Scientific inquiry took millennia to ascertain the true nature of light, and it is not possible here to attempt to recapitulate all of the philosophizing, hypotheses, arguments, and experimentation involved in that great debate. The main point of controversy was whether light should be considered as a particle or as a wave. Empedocles of Acragas (492–432 b.c.e .) was of the opinion that light is a “streaming substance” emitted by luminous bodies, and that light travels at a finite speed ( Sambursky, 1958 ). In the seventeenth century, Isaac Newton postulated that light is composed of particles and that color is connected with the size of those particles; however, his contemporary Christiaan Huygens argued that light is a wave that transfers energy but not substance ( Einstein & Infeld, 1966 , p. 105ff). It turns out that light is indeed a wave propagating via electric and magnetic fields, but in addition to exhibiting properties of waves (such as interference) it also exhibits properties of particles (such as momentum and localization). When treating light as particles, the individual quanta are called photons .