| 释义 |
Planck Physics.|plæŋk|
The name of Max K. E. L. Planck (1858–1947), German physicist, used in the possessive and attrib. to designate various concepts that he invented or discovered, as Planck('s) constant, one of the fundamental physical constants (symbol h), relating the energy E of a quantum of electromagnetic radiation to its frequency ν according to the equation E = hν; approximately 6·626 × 10–34 joule-second; Planck('s) equation or formula, any of the related equations stating Planck's law; Planck('s) law, a law giving the density of radiant energy at a particular wavelength λ or frequency ν inside a perfect radiator, and the flux of radiant energy emitted by it, the former being written as ρ(λ) dλ = (8πhc/λ5) (exp(hc/kλT) {b1} 1)–1dλ or ρ(ν)dν = (8πhν3/c3) (exp(hν/kT){b1} 1)–1dν; Planck oscillator, a concept used by Planck in his work on radiation: an electrically charged particle that can execute simple harmonic motion with a frequency independent of the amplitude; Planck('s) radiation formula or law = Planck('s) law.
1910Phil. Mag. XX. 244 Corpuscles which are emitted by bodies when exposed to ultra-violet light. Ladenburg found that the maximum energy of these corpuscles..was proportional to n the frequency of the light, being of the order h′n/2π where h′ is *Planck's constant. 1935D. L. Sayers Gaudy Night ii. 37 ‘There happened to be an unknown factor.’ ‘Like that thing that keeps cropping up in the new kind of physics,’ said the Dean. ‘Planck's constant, or whatever they call it.’ 1940Glasstone Text-bk. Physical Chem. i. 73 Every particle is associated with a wave.., and the wave length (λ) is related to the mechanical momentum (mυ) by λ = h/mυ, where h is the Planck constant. 1960Chalmers & Quarrell Physical Examination of Metals (ed. 2) xvi. 749 This is known as the spin of the particle and is measured in terms of h/2π..where h is Planck's constant. 1968G. Ludwig Wave Mech. i. iv. 62 This uncertainty relation states that in any experimentally producible ensemble the product of the spread in position and momentum cannot go below a lower limit given by Planck's constant.
1911Bull. Bureau of Standards (U.S.) VII. 393 *Planck's equation for the intensity of radiation J, of wave length λ, from a black body at the absolute temperature θ,..appears to represent the results of all known observations. 1966M. Ferro-Luzzi tr. Fermi's Molecules, Crystals & Quantum Statistics vii. 223 From the Planck equation, we can easily deduce Stefan's law, which also can be obtained by thermodynamic arguments alone.
1905Ld. Rayleigh in Nature 13 July 244/1 In Nature, May 18, I gave a calculation of the coefficient of complete radiation at a given absolute temperature for waves of great length.., and it appeared that the result was eight times as great as that deduced from *Planck's formula. 1923Glazebrook Dict. Appl. Physics IV. 563/2 Throughout the spectrum from 0·5 µ to 50 µ Planck's formula fits the observed spectral energy distribution more closely than any other equation yet proposed. 1974G. Reece tr. Hund's Hist. Quantum Theory ii. 27 By comparing the measured energy densities..with Planck's formula it was possible to calculate h and h/k.
1905Nature 27 July 294/2 *Planck's law is in good agreement with experiment if h is given a value different from zero. 1930Ruark & Urey Atoms, Molecules & Quanta iii. 59 The physical basis for the asymptotic approach of Planck's law to the classical distribution is easily seen. 1955W. Heisenberg in W. Pauli Niels Bohr 14 Bohr explained to him [sc. Schrödinger] that not even Planck's Law could be understood without the quantum jumps. 1974Turner & Betts Introd. Statistical Mech. xii. 148 The Planck law describes the distributions of energy among the infinite range of possible frequencies.
1920*Planck oscillator [see N I. 4 b]. 1966tr. S.-I. Tomonaga's Quantum Mech. II. vi. 111 Each term in Eq. (47·9′) has the form of the Hamiltonian of a Planck oscillator.
1909Sci. Abstr. A. XII. 315 (heading) *Planck's radiation law.
1911Ibid. XIV. 404 It is concluded that the Einstein formula for specific heat is confirmed and also the Planck radiation formula. 1935Pauling & Wilson Introd. Quantum Mech. xi. 301 The density of radiant energy is known to be given by Planck's radiation law as [etc.]. 1974G. Reece tr. Hund's Hist. Quantum Theory xi. 145 The Bose statistics of light quanta was thus the same as that earlier applied by Planck for energy quanta..and thus led to the Planck radiation formula.
▸ attrib. In the names of physical units chosen so as to simplify certain mathematical expressions in cosmology and the theory of gravity. Also in extended use. a. Planck length n. the distance (ℏG/c3)½ (where G is the constant of gravitation), equal to 1.616 × 10-35 metre, which represents the length at which classical concepts of space–time cease to be valid.
[1955J. A. Wheeler in Physical Rev. 97 514/1 The characteristic length, L* = (ℏG/c3)½ = 1.63 × 10-33 cm.] 1964J. A. Wheeler in C. De Witt & B. De Witt Relativity, Groups & Topol. 509 For these fluctuations there is only a single physical constant that is relevant—the Planck length L* = (ℏG/c3)½. 1970Jrnl. Physics A 3 60 A vaguer but more physical motivation is to be found in the significance of the so-called ‘Planck length’,..which constitutes a sort of limit beyond which the concepts of measurement..have no meaning. 1991C. A. Ronan Nat. Hist. Universe 174/1 The size of open strings is roughly equal to the Planck length, a distance of only 10-32 millimetres, equivalent to a hundred-billion-billionth of the diameter of the atomic nucleus. 1993N.Y. Times 30 Mar. c10/4 Perhaps when a black hole evaporates, it leaves behind what is called a remnant... The remnant, it turned out, would take the form of a new kind of elementary particle that would be just the Planck length in size yet would weigh one ten-thousandth of a gram.
b. Planck mass n. the mass that a particle with a wavelength equal to the Planck length would have, equal to (ℏc/G)½ (where c is the speed of light), i.e. 2.177 × 10-5 gram.
1964J. A. Wheeler in C. De Witt & B. De Witt Relativity, Groups & Topol. 508 Only when the mass of an object exceeds the Planck mass (ℏc/G)½ = 2.18 × 10-5 g does its static field become large enough to show up against the background. 1971Progress Theoret. Physics 46 984 The limiting radius and mass of the collapsing extreme relativistic Fermi gas are roughly given by N2/5L* and N2/5m*, respectively, where N is the number of particles in the gas and m*..is the Planck mass. 1981D. Wilkinson in B. Dixon From Creation to Chaos (1993) 324 It is..clear that if we attempt to discuss concentrated masses of greater than a certain magnitude called the Planck mass of about 1019GeV we shall simply not know how to do it. 1989J. Silk Big Bang (rev. ed.) vi. 118 The Planck mass..represents the ultimate building block of nature.
c. Planck density n. a density derived from the Planck mass and the Planck length, of the order of 1093 gram cm-3.
1967E. R. Harrison in Nature 8 July 152/1 We obtain the Planck density ρ ∼ c5/G2ℏ ∼ 1095 g cm-3 when the age of the universe is t* ∼ λ/c or..∼ 10-44. 1971Progress Theoret. Physics 46 984 For any given number N of particles one can obtain a configuration with mass as close to zero as one pleases by prescribing a sufficiently high particle density (of the order of the Planck density ∼ 1094 g/cm3 for small N). 1992S. P. Maran Astron. & Astrophysics Encycl. 147/1 The scope of such theories is limited at present by quantum effects that are expected to become significant..at some density not exceeding the Planck density. 1994Sci. Amer. Nov. 32/2 The current laws of physics..took hold only after the density of the universe dropped below the so-called Planck density, which equals about 1094 grams per cubic centimeter.
d. Planck scale n. the scale of events happening over a distance of the order of the Planck length and in a time of the order of the Planck time.
1968Science 14 June 1200/3 The geometry of space at the Planck scale of distances. 1980Philos. Trans. (Royal Soc.) (A.) 296286, I have outlined how naïve quantum gravitational effects predict metric and density fluctuations of unit amplitude on the Planck scale ca. 10-5 g. 1989J. Silk Big Bang (rev. ed.) vi. 118 At the Planck scale, we need an entirely novel concept in order to describe the state of matter. 1997Sci. Amer. Apr. 42/3 Very little is known with absolute certainty about collisions at energies beyond the Planck scale, but there is a good educated guess.
e. Planck time n. (a) the time (ℏG/c5)½ (where G is the constant of gravitation), or 5.39 × 10-44 second, after the big bang; (b) a unit of time of this duration (equal to the time that light takes to travel the Planck length).
1976Nature 6 May 20/1 If the particle creation occurs near the Planck time, the entropy produced is consistent..with that required by the Einstein equations. 1978Proc. Royal Soc. (A.) 361523 [This] will become of the same order of magnitude as ρrad when t is about 1010 Planck times. 1980Philos. Trans. (Royal Soc.) (A.) 296276 Constant curvature fluctuations arising at the Planck time would be just right. 1988J. Trefil Dark Side of Universe xi. 153 In one version of the superstring theory, which is particularly appealing from an aesthetic point of view, the equations seem to suggest that at the Planck time the universe split into two separate parts. 1994Science 13 May 1000/1 Over the Planck time, a mere 10-43 second later, the wormhole closes. 2000New Scientist 3 June 24/1 There is a point known as the Planck time—within 10-43 seconds of the big bang—when gravity is comparable in strength to the other forces of nature.
f. Planck temperature n. a temperature associated with the Planck energy, of the order of 1032 K.
1979Physics Lett. (B.) 80 360 Grand unified models of elementary particle interactions suggest that there was an early epoch during the big bang while the temperature was slightly less than the Planck temperature, during which no known interactions were in thermal equilibrium. 1989A. Salam in P. Davies New Physics xviii. 489/2 The system of preonic fields should undergo a phase transition at Planck temperature. 2000L. Smolin Three Roads to Quantum Gravity iv. 63 There is a fundamental Planck temperature, which is likely to be the hottest anything can get.
g. Planck energy n. the energy associated with a particle having the Planck mass, of the order of 1029 eV.
1980Progress Theoret. Physics 64 1498 The conjecture that the homogeneity of the Universe might be explained by assuming G ∼ T-2 for T > Planck Energy is analyzed. 1988Nature 25 Feb. 674/3 Einstein's theory of gravity arises in its low-energy limit (with energies much less than the Planck energy 1019Gev). 1997Sci. Amer. Apr. 42/1 If the particles have a ‘Planck energy’ of about 1028 electron volts, so much energy—and therefore mass—becomes concentrated in a tiny volume that gravitational forces outweigh all others. |