Physics
Wave Particle Duality of Light
The wave-particle duality of light is a fundamental concept in physics that describes the dual nature of light as both a wave and a particle. This duality is demonstrated through phenomena such as diffraction and interference, which are characteristic of waves, as well as the photoelectric effect, which is characteristic of particles. This concept revolutionized our understanding of the behavior of light at the quantum level.
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10 Key excerpts on "Wave Particle Duality of Light"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 4 Wave–Particle Duality Wave–particle duality postulates that all matter exhibits both wave and particle properties. A central concept of quantum mechanics, this duality addresses the inability of classical concepts like particle and wave to fully describe the behavior of quantum-scale objects. Standard interpretations of quantum mechanics explain this paradox as a fundamental property of the Universe, while alternative interpretations explain the duality as an emergent, second-order consequence of various limitations of the observer. This treatment focuses on explaining the behavior from the perspective of the widely used Copenhagen interpretation, in which wave–particle duality is one aspect of the concept of complementarity, that a phenomenon can be viewed in one way or in another, but not both simultaneously. The idea of duality originated in a debate over the nature of light and matter that dates back to the 17th century, when competing theories of light were proposed by Christiaan Huygens and Isaac Newton: light was thought either to consist of waves (Huygens) or of corpuscles particles (Newton). Through the work of Max Planck, Albert Einstein, Louis de Broglie, Arthur Compton, Niels Bohr, and many others, current scientific theory holds that all particles also have a wave nature (and vice versa). This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules. In fact, according to traditional formulations of non-relativistic quantum mechanics, wave–particle duality applies to all objects, even macroscopic ones; but because of their small wavelengths, the wave properties of macroscopic objects cannot be detected. Brief history of wave and particle viewpoints Aristotle was one of the first to publicly hypothesize about the nature of light, proposing that light is a disturbance in the element air.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 13 Wave–Particle Duality Wave–particle duality postulates that all matter exhibits both wave and particle properties. A central concept of quantum mechanics, this duality addresses the inability of classical concepts like particle and wave to fully describe the behavior of quantum-scale objects. Standard interpretations of quantum mechanics explain this paradox as a fundamental property of the Universe, while alternative interpretations explain the duality as an emergent, second-order consequence of various limitations of the observer. This treatment focuses on explaining the behavior from the perspective of the widely used Copenhagen interpretation, in which wave–particle duality is one aspect of the concept of complementarity, that a phenomenon can be viewed in one way or in another, but not both simultaneously. The idea of duality originated in a debate over the nature of light and matter that dates back to the 17th century, when competing theories of light were proposed by Christiaan Huygens and Isaac Newton: light was thought either to consist of waves (Huygens) or of corpuscles particles (Newton). Through the work of Max Planck, Albert Einstein, Louis de Broglie, Arthur Compton, Niels Bohr, and many others, current scientific theory holds that all particles also have a wave nature (and vice versa). This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules. In fact, according to traditional formulations of non-relativistic quantum mechanics, wave–particle duality applies to all objects, even macroscopic ones; but because of their small wavelengths, the wave properties of macroscopic objects cannot be detected. Brief history of wave and particle viewpoints Aristotle was one of the first to publicly hypothesize about the nature of light, proposing that light is a disturbance in the element air.
eBook - ePubQuantum Mechanics, Volume 1
Basic Concepts, Tools, and Applications
- Claude Cohen-Tannoudji, Bernard Diu, Franck Laloë(Authors)
- 2020(Publication Date)
- Wiley-VCH(Publisher)
hv. Einstein showed how the introduction of photons made it possible to understand, in a very simple way, certain as yet unexplained characteristics of the photoelectric effect. Twenty years had to elapse before the photon was actually shown to exist, as a distinct entity, by the Compton effect (1924).These results lead to the following conclusion: the interaction of an electromagnetic wave with matter occurs by means of elementary indivisible processes, in which the radiation appears to be composed of particles, the photons. Particle parameters (the energy E and the momentum p of a photon) and wave parameters (the angular frequency ω = 2πυ and the wave vector k, where |k| = 2π/λ, with v the frequency and λ the wavelength) are linked by the fundamental relations:(A-1)where is defined in terms of the Planck constant h:(A-2)During each elementary process, energy and total momentum must be conserved.A-2. Wave-particle duality
Thus we have returned to a particle conception of light. Does this mean that we must abandon the wave theory? Certainly not. We shall see that typical wave phenomena such as interference and diffraction could not be explained in a purely particle framework. Analyzing Young’s well-known double-slit experiment will lead us to the following conclusion: a complete interpretation of the phenomena can be obtained only by conserving both the wave aspect and the particle aspect of light (although they seem a priori irreconcilable). We shall then show how this paradox can be resolved by the introduction of the fundamental quantum concepts.A-2-a. Analysis of Young’s double-slit experiment
The device used in this experiment is shown schematically in Figure 1 . The monochromatic light emitted by the source ℐ falls on an opaque screen 𝓅 pierced by two narrow slits F1 and F2 , which illuminate the observation screen ℰ (a photographic plate, for example). If we block F2 , we obtain on ℰ a light intensity distribution I1 (x) which is the diffraction pattern of F1 . In the same way, when F1 is obstructed, the diffraction pattern of F2 is described by I2 (x). When the two slits F1 and F2 are open at the same time, we observe a system of interference fringes on the screen. In particular, we note that the corresponding intensity I(x) is not the sum of the intensities produced by F1 and F2
eBook - PDF- John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
920 CHAPTER 29 Particles and Waves 29.1 The Wave–Particle Duality The ability to exhibit interference effects is an essential characteristic of waves. For instance, Section 27.2 discusses Young’s famous experiment in which light passes through two closely spaced slits and produces a pat- tern of bright and dark fringes on a screen (see Figure 27.3). The fringe pattern is a direct indication that interference is occurring between the light waves coming from each slit. One of the most incredible discoveries of twentieth-century phys- ics is that particles can also behave like waves and exhibit interference effects. For instance, Interactive Figure 29.1 shows a version of Young’s experiment performed by directing a beam of electrons onto a double slit. In this experiment, the screen is like a television screen and This photograph shows a highly magnified view of a coronavirus that was made with a scanning electron microscope (SEM). The diameter of the roughly spherical virus is approximately 120 nm. In the twentieth century, physicists were astonished when it was discovered that particles could behave like waves. In fact, we will see in this chapter that there is a wavelength associated with a moving particle such as an electron. The microscope used for the photograph takes advantage of the electron wavelength, which can be made much smaller than that of visible light. It is this small electron wavelength that is responsible for the exceptional resolution of the fine details in the photograph. The spike-like structures on the outer surface of the virus are composed of proteins that attach to the cell membrane of the host. A novel coronavirus (SARS-CoV-2) was responsible for an outbreak of coronavirus disease in 2019 (COVID-19) that infected millions of people worldwide. LEARNING OBJECTIVES After reading this module, you should be able to... 29.1 Define wave–particle duality. 29.2 Explain the origin of Planck’s constant from blackbody radiation.
eBook - ePub- Elizabeth Allen, Sophie Triantaphillidou(Authors)
- 2012(Publication Date)
- Routledge(Publisher)
It is now accepted that a complete understanding of the nature of light must recognize both wave and particle theories as valid. This is termed wave–particle duality and is extended in current scientific theory to all matter at a quantum level: the idea that any object existing in the form of particles must also exhibit wave-like behaviour. THE NATURE OF LIGHT Light is a form of electromagnetic radiation (or radiant flux), which is emitted from various sources, most obviously the sun. Electromagnetic radiation is a self-propagating wave of energy which travels through empty space at a particular speed and consists of oscillations in electric and magnetic fields. As established by Maxwell, all electromagnetic radiation travels at the same speed in vacuum, † that is approximately 2.998 × 10 8 ms −1. When electric charges move, they are accompanied by a magnetic field. If the charges accelerate or decelerate, then disturbances occur in both the electric and magnetic fields and radiation is emitted in a wave motion, carrying energy away from the disturbed charges. The fields oscillate at right angles to each other. They are also at right angles to the direction in which the wave is moving. Furthermore, electromagnetic waves exhibit rectilinear propagation – that is, a single point on a wave, if unimpeded, is propagated in a straight line. Electromagnetic radiation exists at a wide range of wavelengths or frequencies and these are collectively termed the electromagnetic spectrum (see page 35). In general, in photography and digital imaging we are more correctly referring to the visible spectrum – that is, the range of wavelengths of electromagnetic radiation that are detectable by the human visual system
eBook - PDFIntroduction to Optics I
Interaction of Light with Matter
- Ksenia Dolgaleva(Author)
- 2022(Publication Date)
- Springer(Publisher)
Max Planck’s observation will be discussed in the third book of this series, where we will cover active optical devices. 1.1.3 RECONCILIATION There exists an apparent contradiction: the two sets of experiments described above, indicate different facts about what light is. On the one hand, interference and diffraction can only be understood if the wave nature of light is accepted. On the other hand, the wave representation does not explain the photoelectric effect, and one has to accept the particle nature of light to understand it. The question that arises as the result of these speculations is: What is light? Is it comprised of waves or particles? And the answer to this question is both. Light exhibits both wave and particle natures simultaneously. Either wave or particle nature comes up explicitly 4 1. LIGHT Figure 1.3: Double-slit experiment with the weak beam of light comprised of photons traveling one-at-a-time through a screen with two slits to a single-photon CCD camera. The subplots rep- resent the image evolution as the data acquisition time becomes longer. The image is an experi- mental shot, courtesy of Prof. A. Weis (Université de Fribourg) and Prof. T. L. Dimitrova (Plov- div). Source: Swiss Physical Society https://www.sps.ch/en/articles/progresses/wave-particle- duality-of-light-for-the-classroom-13/, also published in [5]. under specific experimental conditions, but they both are intrinsic to light. This property of light is termed particle-wave duality. There is one experiment that can serve as reconciliation to this apparent contradiction [5]. Let us assume that a very weak beam of light interacts with a screen with two slits. The widths of the slits are identical and comparable to the wavelength of light. The beam of light is so weak that, if we accept for a moment that the light has corpuscular nature, it will correspond to photons traveling one-at-a-time and interacting with the double-slit screen individually.
eBook - PDFLet There Be Light: The Story Of Light From Atoms To Galaxies (2nd Edition)
The Story of Light from Atoms to Galaxies
- Alex Montwill, Ann Breslin(Authors)
- 2013(Publication Date)
- ICP(Publisher)
405 Chapter 14 Atoms of Light Behaving as Waves We have established that light has the properties of a wave and discussed the evidence in detail. Light spreads out like a wave, it can bend around corners like a wave, and exhibits the proper-ties of diffraction and interference. It must be a wave. Later we described particle properties of light. The light quantum behaves like a bullet. It can knock electrons out of the surface of a metal in the photoelectric effect, and bounce off elec-trons in the Compton effect; it has energy and momentum. It must be a particle. Now that we have got used to the fact that light sometimes looks like a wave and sometimes like a particle, we meet some-thing even more mysterious. We consider what happens when we use a very dim light source so that the photons may be sepa-rated from one another by as much as ten kilometres. We are definitely dealing with individual photons, and yet somehow they have not forgotten their pedigree as a wave! When we send them through an apparatus such as Young’s slits, we still see interference. No photons land where there would have been a dark fringe if a brighter source had been used, even though no two photons are ever close enough to interfere with one another. Somehow the solitary photon behaves as if it had gone through both slits at the same time. The photon is definitely an isolated particle, yet it behaves as a wave. As if this were not strange enough, we can arrange things in such a way that the alternative paths of the photon are not close 406 Let There Be Light 2nd Edition together, as they are in Young’s slits, but are separated by an unlimited distance. Now we discover something which defies logic. Suppose the photon has two possible paths. If we wait for the photon to set out on one path and then close the alternative path, it somehow has an effect on the photon, regardless of how far away the alternative path might be.
eBook - PDF- Mohammad Reza Pahlavani(Author)
- 2012(Publication Date)
- IntechOpen(Publisher)
2 The Physical Nature of Wave/Particle Duality Marcello Cini Università La Sapienza, Roma Italy 1. Introduction 1.1 Waves and particles in quantum mechanics In spite of the fact that the extraordinary progress of experimental techniques make us able to manipulate at will systems made of any small and well defined number of atoms, electrons and photons - making therefore possible the actual performance of the gedankenexperimente that Einstein and Bohr had imagined to support their opposite views on the physical properties of the wavelike/particlelike objects ( quantons ) of the quantum world - it does not seem that, after more than eighty years, a unanimous consensus has been reached in the physicist's community on how to understand their strange properties. Unfortunately, we cannot know whether Feynman would still insist in maintaining his famous sentence It is fair to say that nobody understands quantum mechanics. We can only discuss if, almost thirty years after his death, some progress towards this goal has been made. I believe that this is the case. I will show in fact that, by following the suggestions of Feynman himself, some clarification of the old puzzles can be achieved. This chapter therefore by no means is intended to provide an impartial review of the present status of the question but is focused on the exposure of the results of more than twenty years of research of my group in Rome, which in my opinion provide a possible way of connecting together at the same time the random nature of the events at the atomic level of reality and the completeness of their probabilistic representation by the principles of Quantum Mechanics.
eBook - PDF- Gary N. Felder, Kenny M. Felder(Authors)
- 2022(Publication Date)
- Cambridge University Press(Publisher)
• A wave passing through a very narrow slit spreads out from there in all directions (Huygens’ principle). The result is indistinguishable from particles spreading out. • So if you want to distinguish waves from particles you need to set up some kind of interference, because destructive interference is a property of waves that has no counterpart with particles. • One way to set up that interference is to use two (or more) very narrow slits, so the waves emanating from these slits interfere with each other. • A different way to set up that interference is to make one slit that is wide compared to the wavelength of the light, so the waves emanating from different parts of that one slit interfere with each other. • Either way you do this experiment, if your source was a wave, you will see the “interfer- ence pattern” of light and dark bands. Because we see such a pattern with light, we know that light exhibits wave behavior. 3.2.3 Questions and Problems: The Young Double-Slit Experiment Conceptual Questions and ConcepTests 1. If light were a stream of particles – not a wave at all – what would Young have seen on the back wall of his experiment? 2. You are doing slit experiments with very narrow slits (much narrower than the wavelength λ). Explain in your own words why such a single-slit experiment can’t tell you whether light is a particle or a wave, but a double-slit experiment can. Would a triple slit experiment show a difference between the two? 3. If you do a double-slit experiment with light you will see alternating bright and dark spots. Is the following true or false: if you cover up one of the slits, the dark spots will become brighter? Explain. 4. The interference pattern in the Young double-slit experiment is alternating bands of light and dark. But if you look more closely you will see that the 124 3 The Quantum Revolution I: From Light Waves to Photons middle bright band is the brightest; as you move away in either direction, the bright bands grow dimmer.
- Paul S Braterman(Author)
- 2012(Publication Date)
- World Scientific(Publisher)
You would be wrong. Each separate quantum of light has acted as a particle, at one specific point on the photographic plate. But the probability of it doing so at any point depends on the intensity of a wave. Did this or that particular quan-tum go through the left-hand slit or the right-hand slit? The answer to this question is indeterminate . There is one possible history in which it went through the one, an equally possible history in which it went through the other, and the way in which these possibilities combine follows the arith-metic of interfering wave patterns. The light quantum itself doesn’t know which slit it went through, or if it does, it’s not telling. In short, each individual photon , as the quantum of light is now called, travels as a wave, but acts as a particle, and it is the intensity of that wave that determines the probability of it acting at any one specific point. There is no saying where the photon really is , until it acts, and even then, there is no saying which slit it went through, so there is no saying where it really was before it acted. If you find this description of the world completely unsatisfactory, then you are, as we have seen, in excellent company. Particles are Waves, But No One Understands How This is Possible It gets worse. Physicists are always searching for symmetries in Nature. If light, while travelling as a wave, is emitted and absorbed in particle-like quanta, could it be that ordinary particles might show some of the proper-ties of waves? And does that include the property of being spread out in space? And if so, would that not introduce intrinsic uncertainty into the 184 From Stars to Stalagmites: How Everything Connects behaviour of all matter at very small scales? Yes, to all these questions, according to the “Copenhagen interpretation” of quantum mechanics developed by Niels Bohr and accepted by most (not all) physicists to this day.
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