The Derivation of the Planck Formula
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Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay. -
1 Lecture 26
PHYS 445 Lecture 26 - Black-body radiation I 26 - 1 Lecture 26 - Black-body radiation I What's Important: · number density · energy density Text: Reif In our previous discussion of photons, we established that the mean number of photons with energy i is 1 n = (26.1) i eß i - 1 Here, the questions that we want to address about photons are: · what is their number density · what is their energy density · what is their pressure? Number density n Eq. (26.1) is written in the language of discrete states. The first thing we need to do is replace the sum by an integral over photon momentum states: 3 S i ® ò d p Of course, it isn't quite this simple because the density-of-states issue that we introduced before: for every spin state there is one phase space state for every h 3, so the proper replacement more like 3 3 3 S i ® (1/h ) ò d p ò d r The units now work: the left hand side is a number, and so is the right hand side. But this expression ignores spin - it just deals with the states in phase space. For every photon momentum, there are two ways of arranging its polarization (i.e., the orientation of its electric or magnetic field vectors): where the photon momentum vector is perpendicular to the plane. Thus, we have 3 3 3 S i ® (2/h ) ò d p ò d r. (26.2) Assuming that our system is spatially uniform, the position integral can be replaced by the volume ò d 3r = V. -
An Atomic Physics Perspective on the New Kilogram Defined by Planck's Constant
An atomic physics perspective on the new kilogram defined by Planck’s constant (Wolfgang Ketterle and Alan O. Jamison, MIT) (Manuscript submitted to Physics Today) On May 20, the kilogram will no longer be defined by the artefact in Paris, but through the definition1 of Planck’s constant h=6.626 070 15*10-34 kg m2/s. This is the result of advances in metrology: The best two measurements of h, the Watt balance and the silicon spheres, have now reached an accuracy similar to the mass drift of the ur-kilogram in Paris over 130 years. At this point, the General Conference on Weights and Measures decided to use the precisely measured numerical value of h as the definition of h, which then defines the unit of the kilogram. But how can we now explain in simple terms what exactly one kilogram is? How do fixed numerical values of h, the speed of light c and the Cs hyperfine frequency νCs define the kilogram? In this article we give a simple conceptual picture of the new kilogram and relate it to the practical realizations of the kilogram. A similar change occurred in 1983 for the definition of the meter when the speed of light was defined to be 299 792 458 m/s. Since the second was the time required for 9 192 631 770 oscillations of hyperfine radiation from a cesium atom, defining the speed of light defined the meter as the distance travelled by light in 1/9192631770 of a second, or equivalently, as 9192631770/299792458 times the wavelength of the cesium hyperfine radiation. -
Non-Einsteinian Interpretations of the Photoelectric Effect
NON-EINSTEINIAN INTERPRETATIONS ------ROGER H. STUEWER------ serveq spectral distribution for black-body radiation, and it led inexorably ~o _the ~latantl~ f::se conclusion that the total radiant energy in a cavity is mfimte. (This ultra-violet catastrophe," as Ehrenfest later termed it, was point~d out independently and virtually simultaneously, though not Non-Einsteinian Interpretations of the as emphatically, by Lord Rayleigh.2) Photoelectric Effect Einstein developed his positive argument in two stages. First, he derived an expression for the entropy of black-body radiation in the Wien's law spectral region (the high-frequency, low-temperature region) and used this expression to evaluate the difference in entropy associated with a chan.ge in volume v - Vo of the radiation, at constant energy. Secondly, he Few, if any, ideas in the history of recent physics were greeted with ~o~s1dere? the case of n particles freely and independently moving around skepticism as universal and prolonged as was Einstein's light quantum ms1d: a given v~lume Vo _and determined the change in entropy of the sys hypothesis.1 The period of transition between rejection and acceptance tem if all n particles accidentally found themselves in a given subvolume spanned almost two decades and would undoubtedly have been longer if v ~ta r~ndomly chosen instant of time. To evaluate this change in entropy, Arthur Compton's experiments had been less striking. Why was Einstein's Emstem used the statistical version of the second law of thermodynamics hypothesis not accepted much earlier? Was there no experimental evi in _c?njunction with his own strongly physical interpretation of the prob dence that suggested, even demanded, Einstein's hypothesis? If so, why ~b1ht~. -
Blackbody Radiation: (Vibrational Energies of Atoms in Solid Produce BB Radiation)
Independent study in physics The Thermodynamic Interaction of Light with Matter Mirna Alhanash Project in Physics Uppsala University Contents Abstract ................................................................................................................................................................................ 3 Introduction ......................................................................................................................................................................... 3 Blackbody Radiation: (vibrational energies of atoms in solid produce BB radiation) .................................... 4 Stefan-Boltzmann .............................................................................................................................................................. 6 Wien displacement law..................................................................................................................................................... 7 Photoelectric effect ......................................................................................................................................................... 12 Frequency dependence/Atom model & electron excitation .................................................................................. 12 Why we see colours ....................................................................................................................................................... 14 Optical properties of materials: .................................................................................................................................. -
Ludwig Boltzmann Was Born in Vienna, Austria. He Received His Early Education from a Private Tutor at Home
Ludwig Boltzmann (1844-1906) Ludwig Boltzmann was born in Vienna, Austria. He received his early education from a private tutor at home. In 1863 he entered the University of Vienna, and was awarded his doctorate in 1866. His thesis was on the kinetic theory of gases under the supervision of Josef Stefan. Boltzmann moved to the University of Graz in 1869 where he was appointed chair of the department of theoretical physics. He would move six more times, occupying chairs in mathematics and experimental physics. Boltzmann was one of the most highly regarded scientists, and universities wishing to increase their prestige would lure him to their institutions with high salaries and prestigious posts. Boltzmann himself was subject to mood swings and he joked that this was due to his being born on the night between Shrove Tuesday and Ash Wednesday (or between Carnival and Lent). Traveling and relocating would temporarily provide relief from his depression. He married Henriette von Aigentler in 1876. They had three daughters and two sons. Boltzmann is best known for pioneering the field of statistical mechanics. This work was done independently of J. Willard Gibbs (who never moved from his home in Connecticut). Together their theories connected the seemingly wide gap between the macroscopic properties and behavior of substances with the microscopic properties and behavior of atoms and molecules. Interestingly, the history of statistical mechanics begins with a mathematical prize at Cambridge in 1855 on the subject of evaluating the motions of Saturn’s rings. (Laplace had developed a mechanical theory of the rings concluding that their stability was due to irregularities in mass distribution.) The prize was won by James Clerk Maxwell who then went on to develop the theory that, without knowing the individual motions of particles (or molecules), it was possible to use their statistical behavior to calculate properties of a gas such as viscosity, collision rate, diffusion rate and the ability to conduct heat. -
Lecture 17 : the Cosmic Microwave Background
Let’s think about the early Universe… Lecture 17 : The Cosmic ! From Hubble’s observations, we know the Universe is Microwave Background expanding ! This can be understood theoretically in terms of solutions of GR equations !Discovery of the Cosmic Microwave ! Earlier in time, all the matter must have been Background (ch 14) squeezed more tightly together ! If crushed together at high enough density, the galaxies, stars, etc could not exist as we see them now -- everything must have been different! !The Hot Big Bang This week: read Chapter 12/14 in textbook 4/15/14 1 4/15/14 3 Let’s think about the early Universe… Let’s think about the early Universe… ! From Hubble’s observations, we know the Universe is ! From Hubble’s observations, we know the Universe is expanding expanding ! This can be understood theoretically in terms of solutions of ! This can be understood theoretically in terms of solutions of GR equations GR equations ! Earlier in time, all the matter must have been squeezed more tightly together ! If crushed together at high enough density, the galaxies, stars, etc could not exist as we see them now -- everything must have been different! ! What was the Universe like long, long ago? ! What were the original contents? ! What were the early conditions like? ! What physical processes occurred under those conditions? ! How did changes over time result in the contents and structure we see today? 4/15/14 2 4/15/14 4 The Poetic Version ! In a brilliant flash about fourteen billion years ago, time and matter were born in a single instant of creation. -
Section 22-3: Energy, Momentum and Radiation Pressure
Answer to Essential Question 22.2: (a) To find the wavelength, we can combine the equation with the fact that the speed of light in air is 3.00 " 108 m/s. Thus, a frequency of 1 " 1018 Hz corresponds to a wavelength of 3 " 10-10 m, while a frequency of 90.9 MHz corresponds to a wavelength of 3.30 m. (b) Using Equation 22.2, with c = 3.00 " 108 m/s, gives an amplitude of . 22-3 Energy, Momentum and Radiation Pressure All waves carry energy, and electromagnetic waves are no exception. We often characterize the energy carried by a wave in terms of its intensity, which is the power per unit area. At a particular point in space that the wave is moving past, the intensity varies as the electric and magnetic fields at the point oscillate. It is generally most useful to focus on the average intensity, which is given by: . (Eq. 22.3: The average intensity in an EM wave) Note that Equations 22.2 and 22.3 can be combined, so the average intensity can be calculated using only the amplitude of the electric field or only the amplitude of the magnetic field. Momentum and radiation pressure As we will discuss later in the book, there is no mass associated with light, or with any EM wave. Despite this, an electromagnetic wave carries momentum. The momentum of an EM wave is the energy carried by the wave divided by the speed of light. If an EM wave is absorbed by an object, or it reflects from an object, the wave will transfer momentum to the object. -
151545957.Pdf
Universit´ede Montr´eal Towards a Philosophical Reconstruction of the Dialogue between Modern Physics and Advaita Ved¯anta: An Inquiry into the Concepts of ¯ak¯a´sa, Vacuum and Reality par Jonathan Duquette Facult´ede th´eologie et de sciences des religions Th`ese pr´esent´ee `ala Facult´edes ´etudes sup´erieures en vue de l’obtention du grade de Philosophiae Doctor (Ph.D.) en sciences des religions Septembre 2010 c Jonathan Duquette, 2010 Universit´ede Montr´eal Facult´edes ´etudes sup´erieures et postdoctorales Cette th`ese intitul´ee: Towards A Philosophical Reconstruction of the Dialogue between Modern Physics and Advaita Ved¯anta: An Inquiry into the Concepts of ¯ak¯a´sa, Vacuum and Reality pr´esent´ee par: Jonathan Duquette a ´et´e´evalu´ee par un jury compos´edes personnes suivantes: Patrice Brodeur, pr´esident-rapporteur Trichur S. Rukmani, directrice de recherche Normand Mousseau, codirecteur de recherche Solange Lefebvre, membre du jury Varadaraja Raman, examinateur externe Karine Bates, repr´esentante du doyen de la FESP ii Abstract Toward the end of the 19th century, the Hindu monk and reformer Swami Vivekananda claimed that modern science was inevitably converging towards Advaita Ved¯anta, an important philosophico-religious system in Hinduism. In the decades that followed, in the midst of the revolution occasioned by the emergence of Einstein’s relativity and quantum physics, a growing number of authors claimed to discover striking “par- allels” between Advaita Ved¯anta and modern physics. Such claims of convergence have continued to the present day, especially in relation to quantum physics. In this dissertation, an attempt is made to critically examine such claims by engaging a de- tailed comparative analysis of two concepts: ¯ak¯a´sa in Advaita Ved¯anta and vacuum in quantum physics. -
Kelvin's Clouds
Kelvin’s clouds Oliver Passon∗ July 1, 2021 Abstract In 1900 Lord Kelvin identified two problems for 19th century physics, two“clouds” as he puts it: the relative motion of the ether with respect to massive objects, and Maxwell-Boltzmann’s theorem on the equipartition of energy. These issues were eventually solved by the theory of special relativity and by quantum mechanics. In modern quotations, the content of Kelvin’s lecture is almost always distorted and misrepresented. For example, it is commonly claimed that Kelvin was concerned about the UV- catastrophe of the Rayleigh-Jeans law, while his lecture actually makes no reference at all to blackbody radiation. I rectify these mistakes and explore reasons for their occurrence. 1 Introduction In 1900, Lord Kelvin, born as William Thomson, delivered a lecture in which he identified two problems for physics at the turn of the 20th century: the question of the existence of ether and the equipartition theorem. The solution for these two clouds was eventually achieved by the theory of special relativity and by quantum mechanics [1]. Understandably, these prophetic remarks are often quoted in popular science books or in the introductory sections of textbooks on modern physics. A typical example is found in the textbook by Tipler and Llewellyn [2]: [...] as there were already vexing cracks in the foundation of what we now refer to as classical physics. Two of these were described by Lord Kelvin, in his famous Baltimore Lectures in 1900, as the “two clouds” on the horizon of twentieth-century physics: the failure of arXiv:2106.16033v1 [physics.hist-ph] 30 Jun 2021 theory to account for the radiation spectrum emitted by a blackbody and the inexplicable results of the Michelson-Morley experiment. -
Useful Constants
Appendix A Useful Constants A.1 Physical Constants Table A.1 Physical constants in SI units Symbol Constant Value c Speed of light 2.997925 × 108 m/s −19 e Elementary charge 1.602191 × 10 C −12 2 2 3 ε0 Permittivity 8.854 × 10 C s / kgm −7 2 μ0 Permeability 4π × 10 kgm/C −27 mH Atomic mass unit 1.660531 × 10 kg −31 me Electron mass 9.109558 × 10 kg −27 mp Proton mass 1.672614 × 10 kg −27 mn Neutron mass 1.674920 × 10 kg h Planck constant 6.626196 × 10−34 Js h¯ Planck constant 1.054591 × 10−34 Js R Gas constant 8.314510 × 103 J/(kgK) −23 k Boltzmann constant 1.380622 × 10 J/K −8 2 4 σ Stefan–Boltzmann constant 5.66961 × 10 W/ m K G Gravitational constant 6.6732 × 10−11 m3/ kgs2 M. Benacquista, An Introduction to the Evolution of Single and Binary Stars, 223 Undergraduate Lecture Notes in Physics, DOI 10.1007/978-1-4419-9991-7, © Springer Science+Business Media New York 2013 224 A Useful Constants Table A.2 Useful combinations and alternate units Symbol Constant Value 2 mHc Atomic mass unit 931.50MeV 2 mec Electron rest mass energy 511.00keV 2 mpc Proton rest mass energy 938.28MeV 2 mnc Neutron rest mass energy 939.57MeV h Planck constant 4.136 × 10−15 eVs h¯ Planck constant 6.582 × 10−16 eVs k Boltzmann constant 8.617 × 10−5 eV/K hc 1,240eVnm hc¯ 197.3eVnm 2 e /(4πε0) 1.440eVnm A.2 Astronomical Constants Table A.3 Astronomical units Symbol Constant Value AU Astronomical unit 1.4959787066 × 1011 m ly Light year 9.460730472 × 1015 m pc Parsec 2.0624806 × 105 AU 3.2615638ly 3.0856776 × 1016 m d Sidereal day 23h 56m 04.0905309s 8.61640905309 -
Measurement of the Cosmic Microwave Background Radiation at 19 Ghz
Measurement of the Cosmic Microwave Background Radiation at 19 GHz 1 Introduction Measurements of the Cosmic Microwave Background (CMB) radiation dominate modern experimental cosmology: there is no greater source of information about the early universe, and no other single discovery has had a greater impact on the theories of the formation of the cosmos. Observation of the CMB confirmed the Big Bang model of the origin of our universe and gave us a look into the distant past, long before the formation of the very first stars and galaxies. In this lab, we seek to recreate this founding pillar of modern physics. The experiment consists of a temperature measurement of the CMB, which is actually “light” left over from the Big Bang. A radiometer is used to measure the intensity of the sky signal at 19 GHz from the roof of the physics building. A specially designed horn antenna allows you to observe microwave noise from isolated patches of sky, without interference from the relatively hot (and high noise) ground. The radiometer amplifies the power from the horn by a factor of a billion. You will calibrate the radiometer to reduce systematic effects: a cryogenically cooled reference load is periodically measured to catch changes in the gain of the amplifier circuit over time. 2 Overview 2.1 History The first observation of the CMB occurred at the Crawford Hill NJ location of Bell Labs in 1965. Arno Penzias and Robert Wilson, intending to do research in radio astronomy at 21 cm wavelength using a special horn antenna designed for satellite communications, noticed a background noise signal in all of their radiometric measurements.