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. T

    Singularities, Density, and the Planck Length

    It is generally accepted that a star of sufficient mass collapsing in on itself will form a black hole (singularity) where density is infinite. I see a few problems arising with this, and I would like to have them clarified. 1.) Density=mass/area If the mass of any star is finite, how can an...
  2. R

    World within Planck Scale & QM/GR Unification

    After reading more about Loop Quantum Gravity. I realized they tried to solve quantum gravity by literally sweeping Planck scale under the rug. That is. The smallest volume and area of the spin networks in LQG is Planck size. In String Theory, they make the string Planck size too. They are just...
  3. D

    Planck Mission and M-Theory Cosmology

    A ways back, I seem to remember reading on the Planck Mission page that it's observations of the CMB could help foster support for M-theory cosmology and weaken support for Inflation, or vice-versa. I thought it had something to do with detection of Non-Gaussianity in the CMB. I could not...
  4. R

    Particles are really planck size?

    It is said fundamental subatomic particles don't have size but just points. Yet particles can be modeled by strings that is Planck size. Does it mean particles like electrons and quarks are Planck size?? Or could they be bigger?? But in scattering, we can measure the particles. So it seems to...
  5. R

    Is Quantum Gravity only related to Planck Scale?

    Is the need for Quantum Gravity only related to understand what goes on in the Planck Scale between quantum fields and curvature of spacetime where they collide. Or is it a more general solution to how quantum object is connected to spacetime (or quantum spacetime)? Let's take the example of a...
  6. P

    Planck CMB map - what to expect?

    If I'm correct Planck will publish its all-sky CMB map (foreground deducted) this year. What's to be expected from this? Is another revolution coming?
  7. R

    Exploring the Connection between Planck Scale Mass and Gravity

    Lisa Randall's states in the book "Warped Passages" dealing with the Hierarchy Problem: "The Plank scale energy determines the strength of gravitational interactions...the strength is inversely proportional to the second power of that energy...A huge Plank scale mass is equivalent to...
  8. marcus

    New Limits on Planck Scale Lorentz Violation (Floyd Stecker)

    http://arxiv.org/abs/1102.2784 New Limits on Planck Scale Lorentz Violation from Gamma-ray Burst Polarization Floyd W. Stecker 3 pages, submitted to Phys. Rev. Letters (Submitted on 14 Feb 2011) "Constraints on possible Lorentz invariance violation to first order in E/M_{Planck} for photons...
  9. D

    How could spacetime become discretised at the Planck scale?

    In early 2010 I attended this inaugural lecture by string theorist- Prof. Mavromatos entitled 'MAGIC strings'. In it he proposes that some string theory models may violate Lorentz symmetry at the Planck scale resulting in a kind-of foamy spacetime that could be observed by differing arrival...
  10. R

    Numerical Boundary Conditions for Fokker Planck and Kramers equations

    Hi Everyone, Apologies if this is posted in the wrong place. I am trying to produce numerical solutions for the following initial value partial differential equations, namely the overdamped Schmoluchowski equation \frac{\partial p(x,t)}{\partial t}=-\frac{\partial}{\partial...
  11. zonde

    What would happen if Planck constant decreased slightly?

    I have speculative question. What we would expect to see if Planck constant would become marginally smaller? My guess is that vacuum would start to produce black body radiation. Does it seems right?
  12. M

    Why is planck temperature the highest possible temperature

    why is it the highest temperature? what happens if it is exceeded? is there an experimental proof that it is the highest temperature? why the temperature at the time of just after the big bang higher or lower than it?
  13. MTd2

    What is the Planck Scale for AS gravity?

    The coupling constant runs so the Planck scale changes. What is it at the AS point?
  14. wolram

    How much will the planck mission resolve about the universe.

    How much will the Planck mission resolve about the universe.
  15. I

    Is It Possible to Create a Perfect Square Using Planck Lengths?

    Hey guys I'm new here. I have a question about Planck lengths that has been bothering me lately. I'm not exactly well versed in the area of quantum physics, learning most of what I know from documentary shows and articles on the internet, so so this may seem like a stupid question, but...
  16. S

    The derivation of the backward fokker planck equation

    Homework Statement Starting with the F.P. equation, where the probability has been defined in terms of the stationary probability and another probability function, Q(x,t), i am trying to derive the backward F.P. equation in terms of Q(x,t). Homework Equations The F.P. equation provided...
  17. Q

    Planck's Inspiration to Solve Blackbody Radiation

    To solve the the blackbody radiation Planck had to solve the partition function or average energy for a harmonic oscillator. But where did he get the inspiration to change the energy of the harmonic oscillator from E = \frac{1}{2} m v^2 + \frac{1}{2} k x^2 to simply E = n h v This seems like...
  18. N

    Deck of Cards and Planck Time?

    Deck of Cards and Planck Time? This is truly unbelievable. I've checked my work multiple times, gotten it checked by others, and still the same answer remains. There are more ways to rearrange a single deck of cards than there have been Planck times since the Universe began. Number of...
  19. nomadreid

    Planck length - Greene versus classics

    Planck length -- Greene versus classics Brian Greene, in Chapter 10 of "The Elegant Universe", offers a sketch of string theory's version of why massive particles have a minimum size of the Planck length. I give my summary of the argument in the next paragraph, and the question in the following...
  20. P

    Planck Function: Subbing c=λν - Insight Needed

    Expressing Planck's Law as a function of frequency, we have: I(\nu)=\frac{2h\nu^3}{c^2}\frac{1}{e^{\frac{h\nu}{kT}}-1} Expressing this in terms of wavelength, one should get I(\lambda)=\frac{2hc^2}{\lambda^5}\frac{1}{e^{\frac{hc}{\lambda kT}}-1} but I don't see how this is obvious by...
  21. S

    Exploring Loop Quantum Cosmology with the Planck Satellite

    Will the results from the PLanck satellite shed any light on Loop Quantum Cosmology or any other form of matter bounce?
  22. Z

    Speed of light derived from Planck constant?

    I was wondering if the speed of light (c) can be derived from Planck's constant (h) or the opposite way. I know that they are both fundamental constants, but I'm sure they are connected somehow. Saying it on a different way: if Planck's constant would be different, would the speed of light...
  23. M

    General relativity breaks down at Planck scale

    Why? Some measurements confirm this statement? Or this is a theoretical conclusion?
  24. S

    Is the Planck Length real? How do we know?

    I've heard of Stephen Hawking talking about the Planck Length and how nothing could exist at a level smaller than that length. I'd like to know how we know this to be certain. It seems that history has always repeated itself in that when humans see as far as we possibly see we simply just...
  25. E

    Does string/M-theory make falsifiable predictions at planck scale?

    Stephen Hawking's recent book The Grand Design uses M-theory to predict a multiverse, which then does away God via the anthropic principle. A common criticism that string theory makes no experimentally falsifiable predictions which is countered that experiments do not have enough energy to...
  26. N

    Understanding Deviations in Wien's Law for Long Wavelengths

    In his nobel laureate speech. I thought "small values of energy" <=> "long wavelengths"? And for a body of a low temperature T, the maximum is for long wavelengths, so it can't be that either. What did he maen?
  27. A

    Planck relation, relativistic doppler effect, and relativistic mass

    I've been trying to graph an idea I had, but frankly I don't understand SR well enough to ensure my assumptions are correct, and that I'm using the correct formulas. I would appreciate any input/corrections you folks could give. Here's the idea, which I'll follow with my assumptions: Idea...
  28. N

    What does Max Planck mean in this quote?

    out of "The Origin and Development of the Quantum Theory" given somewhere in the 1920's. If you type the title in google, you can read a html copy As a fun historical sidenote, the following quote seems amusing in hindsight:
  29. Chronos

    Is the Planck Density a Hopelessly Outdated View?

    I have a long standing belief the Planck density is the ultimate limit on mass density in the universe - including black hole 'singularities'. Am I hopelessly out of touch with mainstream science? Any input would be appreciated.
  30. H

    Max Planck & Einstein: 1905 Paper on Energy Quantization

    In the PBS documentary on Einstein's E=MC^2, the story makes it seem as if Planck called on Einstein in response to Einstein's paper on E=MC^2 which was published in 1905. But Einstein wrote an earlier paper on the photoelectric effect and the quantization of energy, also in 1905. Was it for...
  31. R

    Exploring the Planck Wavelength: The Smallest Possible Measurement

    It there a smallest possible wavelength? And if there is, what is that wavelength?
  32. C

    How Planck explained black body radiation

    If I'm not mistaken he explained it with the theory that light energy can be released only in integer multiples of a constant times the frequency of the light. How did he come to this conclusion? Was it to do with the fact that the higher the temperature, the higher the frequencies of the light...
  33. T

    Can Extra Dimensions in String Theory Be Smaller Than a Planck Length?

    Can an extra dimension of empty space be smaller than a Planck length? Is that why string theory allows those extra dimensions to be smaller than a Planck length? Because they are empty? I remember reading posters on these forums say that space itself can expand faster than the speed...

  34. Planck and Einstein's theories.

    Hi all, I've just started reading upon quantum physics and came across Max Planck. I believe he was the one to state that the oscillating atoms or molecules that emit radiation could only occupy quantum states, whereby photons with energy according to E=hf are emitted when an atom changes...
  35. D

    Why is h-bar rather than h used in Planck units?

    Learning a bit more about Planck units, it looks like a number of arguably arbitrary, or at least pragmatic, choices had to be made, regarding using G versus 4piG, using 1/4piEpsiolon0 versus Epsilon0, and so on, but in the reading I don't see any question that h/2pi, rather than h, is the best...
  36. T

    Planck black body formula question

    Hi all -- I had a question about the Planck black body / Johnson-Nyquist resistor temperature formula: \[ E_{\nu}^{2}d\nu=\frac{4R_{\nu}hd\nu}{e^{h\nu/kT}-1}\] I'm just wondering why the formula has $ exp(h\nu/kT)-1$ in the denominator? I would have expected $ exp(h\nu/kT)+1$ as...
  37. O

    Derive Stefan-Boltzmann Law from Planck Distribution for blackbody radiation

    Homework Statement Starting with the Planck distribution R(\lambda,T) for blackbody radiation. (a) Derive the blackbody Stefan-Boltzmann law (ie total flux is proportional to T4) by integrating the above expression over all wavelengths. Thus show that R(T) =...
  38. K

    Max Planck Institute (Heidelberg) Reputation for PhDs in Physics

    I am considering PhD positions in Physics. Can you guys tell me how reputable Max Planck institute (Heidelberg) is compared to top universities? Thank you.
  39. Z

    Finding Planck time in terms of [G], [h], and [c]

    Homework Statement Find a set of 3 exponents a, b, g such that the quantity [G]^a [h]^b [c]^g has dimensions of time. In other words: [T] = [G]^a [h]^b [c]^g (hint: you should get 3 algebraic equations in the 3 unknowns a, b, g which are not that hard to solve. Now determine the socalled...
  40. M

    Traveling at c-(1 planck length/planck time), then accelerate. What happens?

    Amateur so go easy on me. Let's say you're traveling so close to c that you are only 1 Planck length/planck time slower. Seems like you have to increase speed in increments of Planck lengths/planck times (correct me if I'm wrong). Presumably to go any faster, you'd have to skip right to c...
  41. Orion1

    How Do Planck Scale Dimensions Define Universal Limits?

    Planck energy: E_P = m_P c^2 = \sqrt{\frac{\hbar c^5}{G}} Gravitational radius: r_G = \frac{r_s}{2} = \frac{G m_P}{c^2} Gravitational radius is equivalent to Compton wavelength: r_G = \overline{\lambda}_C \frac{G m_P}{c^2} = \frac{\hbar}{m_P c} Planck force is a constant in the Einstein...
  42. H

    Planck length and the speed of light

    How can the Planck length and the speed of light both be universal constants? Will the Planck length change depending on your frame of reference? :)
  43. 6

    Did Planck view light as a particle or a wave?

    Did Planck think that light was a particle or a wave?
  44. 1

    Help: Planck Scale and Fine Structure Constant

    Could someone explain the relationship between the FSC and the Planck Scale? What are they in relation to each other. I know what the Planck Scale is, and I even have a loose understanding of the FSC, but what of them in contrast and comparison? And how does the FSC affect QM, if at all...
  45. N

    Planck function expressed in Wavenumber?

    Homework Statement I am checking some equations for my simulation and are looking at the Planck function. My question involves the constant used for the Planck function expressed in Wavenumbers. I have found this expression for the function...
  46. ZapperZ

    Lorentz invariance verified almost to Planck scale?

    So whose quantum gravity theory will crash-and-burn if this is correct? http://physicsworld.com/cws/article/news/40834 Zz.
  47. A

    Who has done research on the Planck wall

    I am interested if you know somebody who did research, a theory beyond the Planck length, equal to 1.616252(81)×10−35 meters; between 0 meters and Planck length. Are some Big Bang theories...
  48. F

    Exploring the Planck Length & Quantum Effects

    "The Planck length is the scale at which classical ideas about gravity and space-time cease to be valid, and quantum effects dominate. This is the ‘quantum of length’, the smallest measurement of length with any meaning." What I am wondering about this description is the word "dominate"...
  49. LarryS

    Wavelength Less Than Planck Length?

    It seems like if you accelerated a massive particle to a high enough velocity (momentum), you could get it's wavelength to be less than the Planck Length. Does that make sense? As always, thanks in advance.
  50. snoopies622

    Also about the Planck hypothesis

    These questions are rather like the one mahela007 just asked, but are perhaps a little more specific. I have never clearly understood how the Planck hypothesis (E=nhf for the oscillators of a black body) fits into the later quantum theory of Schrodinger, Heisenberg, et al. Specifically...
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