What is Planck: Definition and 388 Discussions

Max Karl Ernst Ludwig Planck, (German: [maks ˈplaŋk] (listen); English: ; 23 April 1858 – 4 October 1947) was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918.Planck made many substantial contributions to theoretical physics, but his fame as a physicist rests primarily on his role as the originator of quantum theory, which revolutionized human understanding of atomic and subatomic processes. In 1948, the German scientific institution Kaiser Wilhelm Society (of which Planck was twice president) was renamed Max Planck Society (MPS). The MPS now includes 83 institutions representing a wide range of scientific directions.

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  1. J

    Why don't strings have a huge Planck mass?

    If a string has a Planck length then why doesn't it have a huge Planck mass? Perhaps it does but its negative gravitational self-energy counteracts this huge positive mass/energy. Maybe a closed string can be thought of as a Planck energy electromagnetic wave trapped by its own...
  2. C

    What are the preliminary results from the Planck First Light Survey?

    The Planck team have put out a press release their (very preliminary) results for the First Light Survey: http://www.esa.int/SPECIALS/Planck/SEM5CMFWNZF_0.html The basic gist: the instrument is working, and it's already producing higher-resolution and lower-noise maps than WMAP offers at the...
  3. J

    Programming to find Planck distribution

    hi everyone, one of my homework questions asks me to write a computer program to evaluate the Planck distribution at any temperature and wavelength and add it to a routine for evaluating integrals for the energy density of the radiation between two wavelengths. I have never used any programming...
  4. U

    The structure of quantum geometry of spacetime at the Planck scale

    http://img233.imageshack.us/img233/5816/espaotempoquntico1.th.jpg Two pictures of quantum spacetimes... The theory of quantum gravity (LQG) can perform calculations and predictions on the concrete structure of space and time at the Planck scale. Equations formulas that describe...
  5. N

    Is there a limit to the information contained within the Planck scale?

    In his book THE BLACK HOLE WAR, 2008, Leonard Susskind makes the following comments around page 135-137: In the following he happens to be referring to a Planck scale cube...let's ignore that specific geometric shape... (Later in the book of course he describes his holographic...
  6. A

    Unifying Relativity and Quantum Mechanics: The Challenge of Planck Units

    Are Planck units the same in all frames of reference ? If so, shouldn't the theory of relativity be modified to account for this ? (same as considering the speed of light the same in all reference frames) Because in it's current form, for a large enough velocity, through length contraction we...
  7. D

    Planck Units: Mass and Length

    I was always puzzled by the fact that while almost all Planck units are extreme (very high or very low), Mass and Energy are exception from that rule. Planck mass is in the ‘middle’ of the spectrum, and it divides the mass spectrum into 2 parts: For small masses/energies m << Mplanck we can...
  8. H

    Sampling at 1/n Planck Time: Synchronizing Samplers and Analyzing Data Values

    Can we synchronize n samplers so that the system is being sampled at 1/n Planck time? What could we tell about the data values between two adjacent samples?
  9. F

    The W boson mass is exp(-4pi^2) of a Planck mass

    Almost: the result is 85 GeV, the measured mass is 80.4 GeV. Is there anybody who has ever looked at this coincidence? François
  10. marcus

    Videos from Planck Scale conference now online

    http://www.ift.uni.wroc.pl/~planckscale/movie/ The first one I intend to watch is Steve Carlip's He is talking about similarities that have emerged among different approaches to QG. In particular evidence for reduction of dimensionality as you zoom in (inspect the spacetime geometry at smaller...
  11. N

    Cosmological Constant and Planck Length in relativity

    There seems to be a difference in the way relativity views Planck length as frame dependent and the cosmological constant, an energy density?, as invariant...Any insights appreciated! There is a well known contradiction between relativity and the Planck length: Wikipedia explains the...
  12. marcus

    A string theorist reports on the Planck Scale conference

    Jose Figueroa is in the Math Physics group at Edinburgh and his research centers on string and susy: http://www.maths.ed.ac.uk/~jmf/ There was a big conference in Poland just now (ending today 3 July) which was interesting partly because it was mixed. Stringers gave talks alongside nonstring...
  13. H

    What is the value of the fine structure constant at Planck energy?

    At low energy, the value is around 1/137.036. What is the value at the Planck energy? Is it listed somewhere? After all, the renormalization of the charge (as it is also called) is mentioned everywhere. But numbers are rare ... Hz
  14. A

    How far does an object traveling slower than light travel in the same distance?

    If this is in the wrong section, I apologise, and would appreciate it if a forum veteran would show me the wrongs of my ways. Homework Statement In one of Zeno's paradoxes, it is argued that travel over any finite distance is impossible, because the distance can be divided an infinite...
  15. N

    Planck Distribution Homework Solution

    Homework Statement I can't find the proof of "the ratio of the number of oscillators in their (n+1) )th quantum state of excitation to the number in nth quantum state is: k is boltzman costant N_(n+1)/N_(n)=exp(-hω/2π(kT)" Homework Equations The Attempt at a Solution:-( I don't have any idea
  16. T

    Planck invents a better yardstick

    The topic was taken from Chapter 5 in Prof. Susskind's book, The Black Hole War. Prof. Susskind pointed out that once Planck converted the unit such as length, time and mass from the Metric Standard to Planck Standard that allow the Universal constants which are light's speed (c), Gravitational...
  17. N

    Is Planck Charge Related to the Fine-Structure Constant and Plank's Constant?

    Has an entity in the universe ever existed with a charge magnitude of 1.87755e-18 C (planck charge)? When/where could it arise?
  18. D

    Exploring the Planck Length-to-Mass Ratio in Quantum Physics

    does anyone know something about the ratio of Planck length to Planck mass : signification, use in quantum relationships...
  19. M

    Derive Planck Length in terms of c, G, and h_bar

    Homework Statement a. The first part of this problem was to derive the escape speed (Vesc) for a star of mass M and radius R. b. The second part is where I am having trouble. It says to equate the Vesc calculated above and derive a formula for Planck length in terms of c, G, and h_bar...
  20. L

    Why planck scale? let me explain before kill me

    Why we are searching quantum gravity effect at the Planck scale? The question seems very stupid (and may be) but let me explain. I define a quantum object when his action is of the order of Planck constant \bar h. namely A~E \delta t~\bar h. So if i take a small amount of energy E i can take...
  21. T

    Planck scale in extra dimensions

    Hi everybody, it's my first post on here but as i seem to have hit a brick wall with my work I'm hoping somebody might be able to help me :) Homework Statement I'm looking at how the Planck scale is reduced in higher dimensions (ADD theories) and I've managed to reproduce an expression...
  22. marcus

    Source material on how Planck came up with h

    I found a facsimile of the original article where Planck gives a value for h (except that in May 1899 he was calling it b, instead of h.) http://bibliothek.bbaw.de/bibliothek-digital/digitalequellen/schriften/anzeige/index_html?band=10-sitz/1899-1&seite:int=454 Here is the exact page where...
  23. P

    How did Planck come up with 'h'?

    In my new found passion to understand the "inner meaning" of this thing called quantum theory, I've been trying to find Planck's derivation of -- or explanation for choosing -- the "constant of nature" that has become so popular. I expected to be able to find the empirical basis for it very...
  24. D

    Planck Scale and Unification of Forces- new research studies

    How do Planck's photon theories relate to the belief that all forces may be unified at high speeds? I understand that light waves can act as particles, and particles can act as light waves. Waves/particles emit energy. And Planck's scale is believed to be around the length of convergence of...
  25. F

    Did Planck's Original Blackbody Radiation Theory Overlook Zero Point Energy?

    Hi all, in a couple of books I read that Planck's original derivation of the blackbody radiation had some problem related to the zero point energy, which was solved after quite a few years (when Schroedinger formulated his equation). I sort of see this problem, but I'm not sure the...
  26. R

    Large Extra Dims and a derived Planck Mass

    Hey folks, I just had a thought I wanted to share with you guys. Just to review first the idea of Large extra dims before I make the comment: The higher dimensional Einstein-Hilbert action is given by S_{bulk}=-\frac{1}{2}\int d^{4+n}x\sqrt{g^{4+n}}\tilde{M}^{n+2}\tilde{R} where...
  27. K

    Textbook talks about Planck time

    A section in my textbook talks about Planck time, but I still don't quite get what does it mean after I finished reading it. I am also wondering whcih laws of physics can be applied to the Planck time. Some info that might be helpful for answering this question: tp=√(Gh/c^5) where G is the...
  28. R

    Does the Planck length grow with the scale factor?

    What happens to the Planck length due to the expansion? Does it grow with the scale factor?
  29. A

    How to get the prefactor for the Planck Distribution

    So I have a question on the Planckian (from one of my PhD qualifier practice problems). I'm trying to derive the Planck distribution from the Bose-Einstein distribution, which is, f(\epsilon) = \dfrac{1}{e^{\frac{\epsilon - \mu}{k_B T}} - 1} Now I know that I can set the chemical...
  30. Orion1

    Planck Boson: The Missing Piece in Unifying Gravity and Quantum Forces

    According to my research on the Standard Model, gravitation is mediated by a massless graviton with spin 2. Upon examining the unity of comparison between cosmic time and quantum unification listed in reference 1, the unification of two forces is scaled at the rest mass (energy) of their bosons...
  31. F

    Planck Spectrum and wavelength subsitution

    All the below is presented in latex format. In Schroeder's intro to thermal, problem 7.38, he asks you to substitute \lambda = \frac{hc}{\epsilon} into the following equation \frac{U}{V} = \int^{\infty}_{0} \frac{8 \pi \epsilon^{3}/(hc)^{3}}{e^{\epsilon / kT}-1} d \epsilon...
  32. J

    How can the Planck length be claimed to be the smallest length?

    Many arxiv papers state that the Planck length is the smallest measureable length. On the other hand, the gravitational length L=2Gm/c^2 associated with every electron or proton is 19 or 22 orders of magnitude smaller than the Planck length. Nobody seems to doubt either of the two statements...
  33. H

    Numerically integrating the Planck distribution

    I'm working on a project that requires me to numerically integrate the Planck spectral distribution. The object is to find the median wavelength, with exactly 50% of the radiance on either side. I'm using a standard composite Simpson rule method and I get good convergence with temps around...
  34. R

    Thick as a planck and making a spectra of myself

    for hv>>kT how does exp(hv/kT) compare to 1? I understand hv >>KT leads to an exponential fall in brightness but why did Planck introduce 1 in his equation. and only for values hv<<kT can this exponential be expanded! Thanks for any help!
  35. S

    Understanding Classical Physics: The Role of Planck Constant

    If the Planck constant tends to zero, it's obviously just getting smaller, so how would this describe classical physics? Is this a way of explaining it?: If energy spacing E = hv, and h --> 0, then E --> 0, which is essentially a continuous energy spectrum and quantization and discreteness...
  36. H

    Planck energy is a max, is there a mimimum too?

  37. D

    Is Space Discrete or Continuous in a Planck World?

    On a ruler, you could move from the 1cm marking on a ruler to the 2cm marking, or you could move from the 0.5cm marking to the 1.5cm marking - both are 1cm movements but you cannot go from 1.5cm to 1cm in a 1cm movement. If we had Planck co-ordinates, could you move from 1 => 2 and also 1.5 =>...
  38. B

    Planck radiation law problem

    Homework Statement Deduce an approximation for Planck's radiation law: To what what wavelength does hv/kT=1 Homework Equations Wien Distribution equation B(lambda)= 2hc^2/lambda^5*exp(-hc/kT(lambda)) Rayleigh-jeans approximation B(lambda)=2ckT/lambda^4 The Attempt at a Solution My...
  39. D

    What happens with causality at the Planck scale? Can effects precede causes?

    What happens with causality at the Planck scale? Can effects "precede" causes? I would like to know what happens with causality at the Planck scale, explained in "educated layman" terms, if that's possible... :) Might effects "precede" causes in time? Do we have to redefine causality at the...
  40. V

    Why are Planck quantities so extreme?

    Why are Planck quantities considered to be maximum and minimum quantities - Planck distance etc ? If they are,then,since in calculus a maximim/minimum is given by,for example,dy/dx = 0,then,for example,y = Planck quantity when x = some other quantity.But what is x?
  41. S

    Deriving the Planck Length, Time, and Mass

    How are the Planck length, Planck time, and Planck mass "derived"? I know their values, but I don't understand where we get them from.
  42. heusdens

    Planck size and Heisenberg and relativity

    Is the Planck time/length/mass affected by relativity, or are they constant (independent of relative velocity and/or gravitation field)? Same question for the Heisenberg Uncertainty Relation. Is it observer dependent?
  43. S

    Susskind on 'variation in Planck length'?

    In "Black Holes, Information and the String Theory Revolution" by Leonard Susskind and James Lindesay, the authors give, (Ch. 15: Entropy of Strings and Black Holes, pg. 170): "The string and Planck length scales are related by g^2* (l_s)^D-2 = (l_p)^D-2 (15.0.23) " They then find...
  44. M

    Is There a Fundamental Unit of Length? Exploring the Planck Circle Problem

    I was doing a thought experiment and came across something that I'm going to term the Planck Circle Problem for the sake of naming it something. The logic is as follows: 1.) All lengths contain an integer number of Planck Lengths. 2.) The radius and circumference of a circle are both...
  45. H

    Planck black-box radiation and the universe

    As a result of my thread about local coordinates, frames distances, calculators etc. , I proceed now with this one about Planck blackbox radiation. I do this because I did not want to disturb other threads where I eventually could fit this in. Because it still has something to do with...
  46. S

    Susskind on 'variation in Planck length'?

    In "Black Holes, Information and the String Theory Revolution" by Leonard Susskind and James Lindesay, the authors give, (Ch. 15: Entropy of Strings and Black Holes, pg. 170): "The string and Planck length scales are related by g^2* (l_s)^D-2 = (l_p)^D-2 (15.0.23) " They then find...
  47. K

    Newton's Third Law, Gravity, and the Planck Length

    If you have a object that is about 10^36 less massive than the Earth (about 10^-12 kg) and say it exerts a force on the Earth about 10^-11 Newtons, this would cause the Earth to accelerate about 10^-36 m/s^2. If this object was away from earth, and say if these objects were initial stationary...
  48. Loren Booda

    Planck - stelactic - cosmological black hole symmetry?

    Like nested dolls, these black holes appear coexisting concentrically where the central stelactic (stellar-galactic) black hole mediates a symmetry between the other two. For instance, consider how stelactic Hawking radiation manifests under inversion of its event horizon. The events within...
  49. W

    Planck average energy reduce to Boltzmann energy

    Hi I'm new here with new problem. I have to show how can the Planck average energy reduce to Boltzmann energy in the limit of no quantization, but I have some problems to understand how should I solve this. If you have any ideas or answers or maybe some materials please send me a MAIL or...
  50. wolram

    Exploring the Limits of Travel: Planck Lengths

    Take a circle that can be (traveled) by some thing, then keep reducing it in size until distinct Planck lengths are reached, does this mean that the traveler can not move any more, as there is no such thing as half a Planck length ?
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