“MATTER” by Gary Zukav Article by C.D.Norman This is a brief summery of the evolution of the concept of “matter” as described by Gary Zukav, a Chinese scholar and scientist brought up in the west, in his book “The Dancing Wu Li Masters” Now and then he compares the thoughts of modern western scientists (physicists) with eastern philosophy and Buddhist teachings. In making up this summary I have omitted the ancient philosophy and stuck to western scientists. In the later part of the 17th century Newton studied „light‟ and „motion‟. By passing a beam of sunlight through a glass prism he observed that white light consists of seven different colours of the rainbow. He also stated the three laws of motion and enunciated the Law of Gravity. His Law of Gravity was applicable not only to bodies on the earth but to motions of all celestial bodies and remains a useful tool in the hands of astronomers. But after a lapse of three centuries Newton‟s laws were questioned by later scientists in the light of new knowledge about light , matter, energy etc. This book traces the development in the concept of matter and energy Newton‟s first great contribution to science was the laws of motion. His first law of motion defied Aristotle‟s notion that a moving body naturally is inclined to come to rest. Newton‟s second great contribution to science was his law of gravity which dismissed the earlier notion of gravity. Newton showed by the phenomenon of universal gravity that the universe was structured in a rational and comprehensive way. He saw his laws as manifestation of God‟s perfection. They enhanced His dignity and vindicated His importance in the universe. In 1911 Ernest Rutherford created his model of atom He said that atoms consisted of two parts, the central heavy part consisting of protons and neutrons surrounded by light particles, electrons in orbital motion around the nucleus, just like the solar system. In 1911 Ernest Rutherford created his model of atom He said that atoms consisted of two parts, the central heavy part consisting of protons and neutrons surrounded by light particles, electrons in orbital motion around the nucleus, just like the solar system. When sodium light is spectroanalysed two bright yellow lines characteristic of the metal is obtained. Similarly, other elements when heated or excited emit light which give bright line spectrum typical of each element. Why and how do these elements produce their spectrum when they are incandescent? Niels Bohr, a Danish Physicist, in 1913, came out with a different picture of the atom. He observed that the spectrum of Hydrogen, the simplest of all elements contained over one hundred lines! How was this possible when Hydrogen atom contained only one proton and one electron? Niels Bohr explained that the electrons around the nucleus of an atom are not at any distance from the nucleus but in orbit or shells at specific distance from it. Each of these shells contained up to a certain number of electrons and no more. In a normal atom of an element its electrons are at their lowest energy level and when heated (excited) they jump from their ground state to higher orbits carrying the energy absorbed by them. But soon they return to their original orbit either directly or by stages releasing the absorbed energy, in the form of light, at each stage of their fall to their original orbit. Bohr discovered that all the possible combination of jumps that a hydrogen electron can make on its journey back to the ground state equals the number of lines in the hydrogen spectrum. Each jump downward releases light of a specific colour depending upon the amount of energy released. From this physicists could calculate the frequencies of light given off by hydrogen atom. Quantum mechanics forced itself upon the scene at the beginning of the 20th century. A quantum is a quantity of something, a specific amount. Quantum theory views subatomic particles as “tendencies to exist” or “tendencies to happen”, not as a particle as dust particle. It is a quantum, a quantity of something which is left to speculation At the subatomic level, mass and energy change unceasingly into each other. The mass of a subatomic particle is expressed in energy unit – electron volt The old physics assumes that there is an external world which exists apart form us that we can observe, measure, and speculate about the external world without changing it. The new physics of quantum mechanics tells us clearly that it is not possible to observe reality without changing it. The old science was “objective” when studying nature. According to quantum mechanics there is not such thing as objectivity. We are part of nature, we cannot eliminate ourselves from the picture. The descent downward from the macroscopic to microscopic level is a two step process – first the atomic level and the second the subatomic level. If a baseball were the size of the earth, its atoms would be the size of a grape. If an atom is magnified to the size of a fourteen storey building, the nucleus would be the size of a grain of salt and the electron just a particle of dust. Newtonian physics has proven inadequate to explain particle behaviour Because there are millions and millions of particles in the smallest space, it is convenient to deal with them statistically, picture their crowded behaviour and not how an individual particle will behave. In quantum mechanics there is no way to predict individual event. Quantum mechanics can tell us how a group of particles will behave but of individual particles, it will say how it probably will behave. Probability is one of the major characteristics of quantum mechanics. For example quantum mechanics can predict statistically the disintegration of a radioactive substance but cannot say which individual atom will disintegrate next. Physicists of 1900 assumed that excited electrons in an atom radiated energy smoothly and continuously. But Max Planck said that the basic structure of nature is granular i.e. discontinuous. He discovered that an excited atom radiates energy in spurts, in specific amount, “quantum”. The radiated energy came in “energy packets” in discontinuous spurts. He also discovered Plank‟s constant a certain number which never changes. The energy in each light quantum of a particular colour is given by the product of the frequency of light and Planck‟s constant. All of the energy packets of a particular colour is the same and carry equal amount of energy, but different from the energy packet of other colours. Energy packet of violet is more than that of red light. In 1921 Einstein theorised that light was composed of tiny particles and that a beam of light is like a stream of bullets, each bullet called a „photon‟. He said that each photon carried its own quantum of energy. When light hits the surface of certain metals, electrons on the surface of the metal are dislodged and sent flying off the surface. The momentum and velocity of the displaced electrons were measured This is known as photoelectric effect of light. The velocity of the rebounding electrons depends upon the colour of light but not on the intensity of light. Violet light knocked off electrons with a greater velocity than red light. This shows that photons of violet light have higher energy than photons of red light Using this photoelectric effect of light Einstein concluded that light is made up of particles (photons). Earlier, in 1803, it was shown that light consisted of waves. Young‟s experiment in which he passed a beam of light through two parallel slits close together produced interference pattern, proving light is a form of waves and not particles. Einstein‟s experiment of photoelectric effect showed that light consisted of particles, not waves. Can light be both wave and particle? The wave-particle duality of light is one of the thorniest problems of quantum mechanics. Particle cannot be waves nor waves particles. Light has either to be particles or waves. Or does it depend upon how and what you look for in light? The wave-particle duality prompted the first real step in understanding the newly unfolding quantum theory (in 1924) of Bohr and two of his colleagues. It referred to a tendency to happen, a tendency that in an undefined way existed of itself, even if it never became an event Probability waves were mathematical catalogue of these tendencies. This was quite different from classical probability. “It introduced something standing in the middle between the idea of an event, a strange kind of physical reality just in the middle between possibility and reality. The wave-particle duality lead to probability waves Access to physical world is through experience. What we experience Is not external reality but our interaction with it This is a fundamental assumption of “complementarity” developed by Niels Bohr to explain the wave-particle duality of light. Wave-like characteristics and particle-like characteristics of light are mutually exclusive or complementary aspects of light. Although one of them excludes the other, both of them are necessary to understand light. Light cannot both be waves and particles at the same time: one of them excludes the other. Acceptance without proof is the fundamental characteristics of western religion. Rejection without proof is the fundamental characteristics of western science. In other words religion has become a matter of the heart and science has become a mater of the mind. This regrettable state of affairs does not reflect the fact that, physiologically, one cannot exist without the other. Everybody needs both. Mind and heart are only different aspects of us How can mutually exclusive wave-like and particle-like behaviours both be properties of one and the same light? They are not properties of light. They are properties of our interaction with light. Depending upon our choice of experiment, we can cause light to manifest either as particles or as waves We can cause light to manifest both wave-like properties and particle-like properties by performing Arthur Compton‟s famous experiment. In 1923 Compton fired x-rays which are waves on electrons. The x-rays bounced off the electrons as if x-rays were particles. They did not lose much energy during the collision. However, those x- rays which collided more nearly head-on with electrons were deflected sharply and lost a considerable amount of their kinetic energy in the collision. X-rays were impacting with electrons exactly as billiard balls impact with billiard balls. Compton thus showed that electromagnetic waves like x-rays also had particle like characteristics. He measured the frequencies of the x-rays before and after impact and hence their energy. But particles do not have frequency, only waves have frequencies. The phenomenon which Compton discovered is called “Compton Scattering”. Compton‟s experiment shows that x-rays have both particle and wave characteristic, not one exclusive of the other. While physicists were trying to explain how waves can be particles, De Broglie showed that particles also are waves! Using Planck‟s equation and Einstein‟s, de Broglie determined the wavelength of matter (matter waves). He said greater the momentum of the particle shorter the wavelength of its associated wave. That is the reason why matter waves are not evident in the macroscopic world. At subatomic level, say an electron, the length of its associated wave is longer than the electron itself Davisson – Germer experiment showed electrons reflect off a crystal surface as if electrons were waves. When a beam of electrons is sent through tiny openings like space between atoms in a metal foil, the beam defracts exactly like light waves. Particles do not have wavelength and yet they defract . Electron is hence both a particle and a wave. It is clear hence that light which is made of waves behaves like particles and electrons which are made of particles behave like waves. Every solid has a wavelength – a base ball, a tree, an automobile and people. Only they are so small that they cannot be noticed. Schrodinger hypothesized that electrons are not spherical objects but patterns of standing waves (stationary waves). Each time an electron completes a journey around the nucleus it produces a whole number of standing waves, never a fraction of one. Schrodinger proposed that each of these standing waves is an electron; in other words, electrons are segments of vibrations bounded by the nodes. Shortly before Schrodinger‟s discovery, another Austrian physicist, Wolfgang Pauli discovered that no two electrons in an atom are exactly alike. The presence of electron with one particular set of properties (quantum numbers) excludes the presence of another electron with exactly the same properties within the same atom.. This became known as Pauli‟s exclusion principle. In terms of Schrodinger‟s standing wave theory, Pauli‟s exclusion principal means that once a particular wave pattern forms in an atom it excludes all other of its kind Schodinger‟s equation modified by Pauli‟s discovery shows that there are only two possible wave patterns in the lowest of Bohr‟s energy levels, or shells…Therefore there can be only two electrons in it ,. There are eight different standing wave pattern possible in the next energy level, therefore there can be only eight electrons in it and so on. Although Schrodinger was sure that electrons were standing waves, he was not sure what was waving, and he called it „psi‟ a Greek letter pronounced “sigh” (a wave function and a „psi‟ function are the same thing) The Schodinger wave equation also provides a self consistent explanation of the size of Hydrogen atom. The wave pattern of a system with one electron and one proton (hydrogen atom) in its lowest energy state has the same size as the ground state of hydrogen atom. An atom consists of a nucleus and electrons. The nucleus at the centre of an atom occupies a small part of the volume of an atom. Electrons may be anywhere within the “electron cloud”. The “electron cloud” is made of various standing waves which surround the nucleus. These standing waves are not material; they are patterns of potential. The electron cloud is a mathematical concept, like wave function which physicists have constructed to correlate their experiences. Schrodinger pictured electrons as actually being spread out over their wave patterns in the form of a tenuous cloud. Electron cloud may or may not exist within an atom; no one really knows. However a concept of electron cloud yields the probabilities of finding the electron at various places around the nucleus of an atom and these probabilities have been determined experimentally to be accurate. Heisenberg‟s method of Scattering Matrix (S Matrix) into the new physics lead to the discovery that shook the very foundations of the “exact sciences”. Heisenberg proved that at the sub-atomic level there is no such thing as “exact science” Heisenberg‟s remarkable discovery was that there are limits beyond which we cannot measure accurately, at the same time , the process of nature. These limits are not imposed by the clumsy nature of our measuring devices or extremely small size of the entities that we attempt to measure, but rather by the very way that nature presents itself to us. There exists an ambiguity barrier beyond which we never can pass without venturing into a realm of uncertainty. His discovery became known as “uncertainty principle” The uncertainty principle reveals that as we penetrate deeper and deeper into the subatomic realm, we reach a certain point at which one part or another of our picture of nature becomes blurred, and there is no way to reclarify that part without blurring another part of the picture! This is the primary significance of the uncertainty principle. At the subatomic level, we cannot observe something without changing it. There is no such thing as the independent observer who can stand on the sidelines watching nature run its course without influencing it. Classical physics is based on the assumption that our reality, irrespective of us, runs its course in time and space according to strict causal laws. Not only can we observe it, we can also predict its future by applying causal laws. But we cannot apply Newton‟s laws of motion to individual particles that does not have an initial location and momentum. Newton‟s laws do not apply to subatomic particles. SUBATOMIC PARTICLES Let us start with an ordinary toothpick. It is made of wood; wood is made of fibres; wood fibres are made of cells; cells on magnification reveals pattern of molecules; molecules on high magnification shows pattern of atoms and finally atoms turn out to be patterns of subatomic particles. Matter is actually a series of patterns out of focus. The search for the ultimate stuff of the universe ends with the discovery that there isn’t any. If there is any ultimate stuff of the universe, it is pure energy, but subatomic particles are not “made of” energy; they are energy. What we have been calling matter (particles) constantly is being created, annihilated and created again. This happens as particles interact and it also happens, literally, out of nowhere. When a projectile of subatomic particles strikes a target (particle) both particles are destroyed at the point of impact. In their place are created new particles, all of which are as elementary as the original particles and often as massive as the original particles! - + p Ko + Negative pi meson (-) collides with a proton (p) Both the particles are destroyed and two new Ko - + particles a neutral K meson (Ko) and a lambda particle are created. Both these particles decay - + p spontaneously into two additional particles each. Of these four particles, two are the same particles that we started with. The new particles are created from the kinetic energy of the projectile particle in addition to the mass of the projectile particle and the target particle. Every subatomic interaction consists of the annihilation of the original particles and the creation of new subatomic particles. The subatomic world is a continual activity of creation and annihilation, of mass changing to energy and energy changing to mass. In the light of the quantum theory elementary particles are no longer real in the same sense as objects of daily life, trees or stones. Subatomic activities are studied from the tracks they leave in a bubble chamber which are photographed. But what made these tracks? The best answer that physicists have so far come with is that particles are actually interaction between fields. When two fields interact with each other they do it instantaneously and at one single point – instantaneously and locally. When a bubble chamber photograph of a track is observed under high magnification they look like discontinuous dots rather than a continuous line. These instantaneous and local interaction make what we call particles. In fact, according to the theory, these instantaneous and local interactions are “particles”. The continual creation and annihilation of particles at the subatomic level is the result of the continual interaction of different fields. This theory is called “Quantum Field Theory”, by Paul Dirac, an English physicist. The quantum field theory is premised on the assumption that physical reality is essentially nonsubstantial. Fields alone are real and they are the substance of the universe and not matter. What is available to physicists is usually a black photograph from the bubble chamber with white lines on it. They know that 1) subatomic particles have no independent existence of their own 2) subatomic particles have wave-like characteristics as well as particle-like characteristics 3)subatomic particles actually may be manifestations of interacting fields. They talk of subatomic particles as if they were real little objects that leave tracks in the bubble chamber and have an independent existence. This convention, though not substantiated, has been extremely productive. Over one hundred particles have been discovered so far. The first distinguishing characteristic of a subatomic particle is its mass. By mass of a particle, it is usually meant its rest mass. Its mass when in motion is relativistic mass. The relativistic mass of a particle depends upon its velocity. At 99% of the velocity of light the mass of a particle is seven times its rest mass and at 0.99986 of the velocity of light its mass increases to 60 times its rest mass. The mass of a particle, whether rest mass or relativistic mass are measured in electron volts. It is a unit of energy. The mass of a particle is measured in energy unit. If a particle is in motion it not only has energy of being (its rest mass) but it also has energy of motion (kinetic energy). Both types of energy can be used to create new particles in a particle collision. These particles are listed from the lightest to the heaviest: the group of lighter particles are called “leptons” ; the medium ones “mesons” and heavier ones “baryons”. Some of them do not fit into this framework. For example, photon which is a mass-less particle. A photon when created, instantly travels at the speed of light. It cannot be slowed down nor can it be speeded up beyond the speed of light. The second characteristic of a subatomic particle is its charge. Every subatomic particle has a positive or negative or neutral charge. Electric charge comes in one fixed amount. A particle can carry one or two of the positive or negative charge, but not in between – no fractional charge. Like energy, charge is quantized The third characteristics of a subatomic particle is its spin. The spin of a particle is maintained at the same rate. If the spin rate I altered the particle itself is destroyed. The spin of a subatomic particle is calculated in terms of angular momentum. Angular momentum depends upon the mass and the rate of spinning of an object. Every subatomic particle has a fixed, definite, and known angular momentum but nothing spins1 Physicists use this concept because subatomic particles do behave as if they have angular momentum. The angular momentum of a subatomic particle is based upon Planck‟s constant, which represents the quantized nature of energy emission and absorption. The entire family of leptons, the light-weight particles has a spin of ½ which means that they all have an angular momentum which is ½ of the angular momentum of a photon. The mesons also have particular spin; their angular momenta are either 0, 1, 2, 3, etc of the angular momentum of a photon and not anything in between. Every particle has a counterpart which is exactly like it but opposite in several major respects. This new set of particles are called anti-particles. Example: positive pi meson and negative pi meson. A few particles are their own antiparticles like the photon. The meeting of a particle and its anti-particle always results in instant annihilation of both particles in a puff of light (photons) Conversely, particles and antiparticles can be created out of energy and always in pairs. In 1949, Richard Feynman discovered that space-time maps like those below have exact correspondence with mathematical expressions which give the probabilities of the interactions that they depict. A particle, antiparticle annihilation is shown thus:- An electron (e-) and a positron (e+) collide at the point indicated by a dot, mutually annihilate each other and two photons are created which depart in the opposite directions at the speed of light. Events are indicated in Feynman diagrams by dots. Every subatomic event is marked by the annihilation of the initial particles and the creation of new ones. Here is a Feynman diagram of collision between negative pi meson and a proton particle:- A negative pi meson collides with a proton, annihilate themselves, creating two new particles, a neutral K meson and a Lambda particle. These new particles are unstable and live less than a billionth of a second before they decay : neutral K meson into - and + and Lambda particle into - and p, the original two particles! In the Feynman diagram a particle can be indicated by an arrow upward and an antiparticle by an arrow downward. This is an easy way of telling a particle from an antiparticle. Because the arrowheads distinguish the particles from antiparticles, we can turn the original Feynman diagram around into any position and still we will be able to distinguish one form the other. 1) electron (e-), positron (e+) collision resulting in two photons. 2) electron, photon collision resulting in a positron and a photon 3) Two photons colliding, resulting in an electron and a positron 4) A positron, photon collision resulting in an electron and a photon Subatomic particles do not just sit around being subatomic particles. They are a beehive of activity. An electron constantly emits and absorbs photons. These are not full-fledged photons. They are exactly like photons except that they do not fly off on their own. They are reabsorbed by the electron almost as soon as they are emitted. They are called “virtual” photons. The thing that keeps them from being full fledged photons is their abrupt re-absorption by the electrons that emit them. The virtual photon exists only for about one thousand trillionth (10-15) second. These photons are emitted by electrons in their ground state. They are reabsorbed almost instantaneously so as not to violate the conservation law of mass-energy. Electrons are always surrounded by a swarm of virtual photons. In the case of electrons in their excited state, the energy absorbed by them is imparted to the released photons which are jettisoned with enough energy to keep going, without violating the law of conservation of mass-energy. If two electrons come close enough to each other, so as their virtual photons overlap, the virtual photon emitted by one is absorbed by the other electron. The closer the electrons come together more virtual photons they exchange. The more virtual photons they exchange, the more sharply their paths are deflected the “repulsive force” between them is simply the cumulative effect of these exchanges of virtual photons, the number of which increases at closer range and decreases at longer distances. According to quantum field theory, the electromagnetic force between particles is the mutual exchange of virtual photons Every electrically charged particle continuously emits and reabsorbs virtual photons and/or exchanges them with other charged particles. When two particles with like charge exchange photons they repulsed each other. When particles carrying positive charge exchange virtual photons with particles carrying negative charge, there is attraction. Physicists call this “interaction” rather than attractive or repulsive force. Virtual photons are not visible in a bubble chamber because of their extremely short lives. Their existence is inferred mathematically. That particles exert force on each other by exchanging other particles is a “free creation” of human mind It is not necessarily how nature “really is”, a mental construction which correctly predicts what natures probably is. The most that one can say about this or any other theory in not whether it is “true” or not but only whether it works or not. The strong force keeps atomic nucleus together. It is one hundred times stronger than the electromagnetic force. It is the strongest force in nature known. But it also has the shortest range If a free proton is pushed to within about one ten-trillionth (10-13) of a centimetre of the nucleus, it is suddenly sucked into the nucleus with a force one hundred times more powerful than the repulsive electromagnetic force. This distance is about the size of the proton itself. According to Yukawa, a Japanese scientist, the strong force is the exchange of another type of virtual particle. A nucleon is a proton or a neutron. They are similar to each other except for their charge. He calculated the energy (mass) of this hypothetical particle. Twelve years later this particle was identified as meson. Some time later an entire family of mesons was discovered. A particular meson called “Pion” or pi meson was identified to come in three varieties: positive, negative and neutral A proton, like an electron, is a beehive of activity. It emits and reabsorbs virtual pions which makes it susceptible to the strong force. The simplest proton self-interaction is the emission and reabsorption of virtual pion. First there is a proton, then there is a proton and a neutral pion and then there is a proton again. The new proton and the neutral pion constitute a violation of the conservation law of mass-energy since their mass- energy together is greater than the mass of the original proton. This creation and reabsorption of the neutral pion is done within an extremely short duration of time. There is yet another way in which a proton can interact with itself. It can emit a positive pion and momentarily transform itself to a neutron. First there is a proton, then a neutron and a positive pion and a proton again. Every nucleus is surrounded by a cloud of virtual pions which are constantly emitted and reabsorbed. If a proton comes close enough to a neutron so that their virtual particles overlap it is absorbed into the nucleus. Neutrons and protons also interact between themselves by emitting virtual particles and reabsorbing them. Some of the possible interaction between a proton and a neutron inside a nucleus are shown by the following Feynman diagrams. The universe, according to the physicists, is held together by four fundamental forces: 1) the strong force 2) electromagnetic force 3) “weak” force and 4) gravitational force. Since the first two forces are explained by the existence of virtual particles, physicists assume that the same can be true of the other two forces. The particle associated with gravity is named “graviton” and those associated with weak force are called “W” particles but their existence have not been discovered . They are only theorised. The range of the strong force, relative to the electromagnetic force, is limited because mesons , relative to protons, have so much mass. The momentary creation of a meson out of nothing is a much more flagrant violation of the conservation law of mass-energy than the momentary creation of photons out of nothing. Therefore the creation and reabsorption of a meson must happen much more quickly to stay within the protection of the uncertainty relation between time and energy. Because the lifespan of a meson is limited, its range is also limited. The range of the strong force is only about on ten-trillionth (10-13) of a centimetre whereas the range of the electromagnetic force is much larger, it is infinite. This is because photons do not have rest mass. The only difference between a real photon and a virtual photon is that the creation of a real photon does not violate the law of conservation of mass-energy but the creation of a virtual photon avoids this law momentarily via the Heisenberg uncertainty principle. Particle interactions become quite intricate when virtual particles emit virtual particles which emit virtual particles in a diminishing sequence. Below is a Feynman diagram of a virtual particle (a negative pion) transforming itself momentarily into two more virtual particles, a neutron and an antiproton. This is the simplest of self-interaction. Kenneth Ford gives an example where eleven particles make their transient appearance between the time a proton transforms itself through various virtual particles back to the original proton A proton never remains a simple proton. All particles exist potentially as different combinations of other particles. Each combination has a certain probability of happening. It is ultimately, chance that determines which of these combinations actually occur. Now we come to the most psychedelic aspect of particle physics. Below are Fynman diagrams of three particle interactions. In these diagrams no world line leads up to the and no world line leads away from them. It just happens. It happens literally out of nowhere, for no apparent reason and without any apparent cause. Where there was no-thing suddenly, in a flash of spontaneous existence, there are three particles which vanish without any trace. This type of diagram is called a “vacuum diagram” because the interaction happens in a vacuum. From empty space comes something and that something disappears again into “empty space”. It is not possible according to our usual conceptions for “something” to come out of “empty space”, but at the subatomic level it does, which is what these vacuum diagrams illustrate. In other words there is no such thing as “empty space”. We have come a long way from Newton and his proverbial apple. Nonetheless, apples are a real part of the apparent world. When we eat an apple we are aware of who is eating and what is being eaten as distinct from the action of eating. This idea is clear to us because we have accepted it without question as the basis of our reality. The history of scientific thought, if it teaches us anything at all, it teaches us the folly of clutching ideas too closely. To this extent it is an echo of eastern wisdom which teaches us the folly of clutching anything!
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