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. K

    Confusion Related to Planck Mass

    Hi all, According to quantum mechanics, the graviton is the measure of the smallest amount of curvature possible in space-time. I read that the mass which would be required to create this curvature is Planck Mass which is close to the value 10^-5g. But the elementary particles, like electrons...
  2. R

    How did Max Planck derive his constant H?

    I listened to a lecture the other day that some anomalies in observations compared to theory caused Max Plank to derive his famous Constant.
  3. Buzz Bloom

    How/Why does GR break down in Planck Epoch?

    Wikipedia says: Traditional big bang cosmology predicts a gravitational singularity before this time, but this theory relies on general relativity and is expected to break down due to quantum effects. https://en.wikipedia.org/wiki/Chronology_of_the_universe Although I found other pages, I have...
  4. C

    Size of Universe: Planck Time to Inflation

    What do we know or speculate as to the size of the visible and entire universe between the Planck time and the beginning of explosive inflation?
  5. S

    Planck Stars & FRBs: Rovelli's Hypothesis

    Nor sure if this has already been discussed. But recently Rovelli has suggested the mysterious Fast Radio Bursts might be from Planck Stars : https://www.gravity.physik.fau.de/events/tux3/rovelli.pdf Any thoughts? What are the other explanation and how can resolve this?
  6. klotza

    Insights A Hand-Wavy Discussion of the Planck Length - Comments

    klotza submitted a new PF Insights post A Hand-Wavy Discussion of the Planck Length Continue reading the Original PF Insights Post.
  7. F

    Age of Universe in Planck normalized units

    Hello, I've a problem. I need to find the age of universe in normalized Planck units. In my case, I'm using Planck mass = 1 and: ##H = 1.18 × 10^{-61} \times t_P^{- 1}## With these values, how can I find the age of the universe? Thanks!
  8. Jimster41

    The Impact of Cosmological Expansion on the Planck Length: A Quantum Perspective

    I get that Planck length is derived from h, G and c. But as a theoretical measure of length how is it affected or not affected by cosmological expansion?
  9. B

    Understanding Heisenberg's Principle: x and p instead of delta x and p

    Homework Statement I don't get how you can use x and p instead of delta x and p in Heisenberg's principle. Also why is it just h bar? Isn't it supposed to be h bar/2? Problem 2-iv Homework Equations delta x* delta p >= h bar/2 The Attempt at a Solution I tried to deal with this problem but I...
  10. Garth

    Primordial gravitational wave constraints from Planck 2015

    In today's Physics ArXiv: New constraints on primordial gravitational waves from Planck 2015. Authors Luca Pagano, Laura Salvati, and Alessandro Melchiorri of the Physics Department and INFN, Universita di Roma. Primordial gravitational waves from the universe exiting Inflation get more and...
  11. N

    Dimensional Analysis of Planck Length

    Hello! So in looking at black hole thermodynamics, I came across the equation ## l_p = \sqrt{G\hbar} ## But in doing a dimensional analysis of ## \sqrt{G\hbar} ## I get ## [\sqrt{G \hbar}] = \sqrt{ \frac{Nm^2}{kg^2} \frac{m^3}{kgs} } ## This obviously doesn't amount to a length. What...
  12. Logan Johnston

    How Is This Quantum Analogy Incorrect?

    Homework Statement "Sometimes the idea of the quantum is compared to the units we use for money. A dollar can be divided into smaller units, where the cent is the smallest possible unit. How is this analogy incorrect? Homework Equations E=nhf The Attempt at a Solution My thought is that...
  13. D

    I Is the Planck length the smallest measurable length?

    I read somewhere that you cannot tell the difference in position between a photon (Or any other particle) at some point in time and the same photon (Or other particle) less than a Planck time later, because it would not have traveled further than a Planck length, which apparently is the smallest...
  14. fricke

    What if Planck Constant is Zero? Effects in Quantum Explored

    What is the effect in quantum if Planck constant is zero? Here are some points that I could think of: if Planck constant is zero, the Heisenberg Uncertainty Principles will become zero, therefore either momentum or position of a particle can be known exactly. if Planck constant is zero, both...
  15. G

    Planck Measurements: Meaning or Trite Observation?

    Does anyone here ascribe any particular broader meaning to them? Is that they represent indivisible units a consensus of sorts? Do they have real meaning or are they a kind of trite observation?
  16. newjerseyrunner

    Are Primordial Black Holes Still a Viable Candidate for Dark Matter?

    I've been reading about black holes and dark matter and came across this theory: http://www.nature.com/nature/journal/v329/n6137/abs/329308a0.html where black holes don't completely evaporate, but evaporate until it hits an equilibrium where it's both unable to evaporate anymore (making it...
  17. Isaac0427

    Understanding the Planck Scale

    Hi, So I am a little confused on the Planck scale. Correct me if I'm wrong (I hope this doesn't sound idiotic) but I believe that any field on a classical scale should be able to be quantized and work on a quantum scale/Planck scale, where the Planck length and the Planck time are the...
  18. K

    About role of Planck constant in classical physics

    Hi there, I am confusing on the statement that we have classical physics when Planck constant approaching zero. I search the similar topic in Physics Forums and I saw that most of the answers refer to the size effect. It argues that when we measure something in the scale of meter comparing to...
  19. Alex299792458

    How many cubic planck lengths are in the observable universe?

    If you take the size of the observable universe can you find out how many cubic plank lengths can fit in the observable universe and it doesn't have to be exact just approximation.Also the math and formulas would be helpful too.
  20. Rajkovic

    Does the Planck Unit of Time Support Julian Barbour's Theory on the End of Time?

    I'm reading Julian Barbour the end of time..I don't know if It's a good reading.. According to Planck unit of time (5.39121 × 10^−44 seconds), could the universe be said to have a "frame rate" and "snapshots" (as Julian Barbour mentions) could exist? (and, incidentally, Zeno's arrow paradox...
  21. W

    Planck's Law vs Rayleigh-Jeans Law (Blackbody radiation)

    First time here, and looking for help on this. The 2nd part of this problem, I have seen some posts on and am still reviewing, but haven't found much on the 1st part. Homework Statement 1) Use l'Hopital's Rule to show that $${\lim_{\lambda\rightarrow 0^{+}}=0}\text{ and...
  22. wabbit

    Planck Stars and GR black and white holes

    Rovelli & Vidotto's Planck Stars describes a possible quantum black hole - white hole transition through a quantum bounce somewhat analogous to the LQC bounce. In another thread, @marcus pointed out to me that this was not necessarilly considered the most likely scenario for a QG black hole. Is...
  23. T

    Covariance betw scalar amplitude & spectral index in Planck?

    I am reading some of "Planck 2013 results. XXII. Constraints on inflation." The paper is full of values for various inflationary parameters under various models, with their confidence intervals. For instance, in Table 5 on page 13, the authors report that — for a model including both running of...
  24. E

    Markopoulou geometrogenesis planck similar to LQG?

    Markus or others who are familiar with this.. I am aware Fotini Markopoulou Geometrogenesis occurs only during the Big Bang. But I'd like to know if it's Planck scale structure a present (after the Big Bang) is similar to the Planck scale structure of Loop Quantum Gravity? If they were not...
  25. P

    Dodecahedron universe after PLanck

    A number of years ago , it was conjectured that space was finite and shaped like a dodecahedron. The claim was "data from the first year of the WMAP satellite – unveiled in February - agreed with the predictions of the standard big bang plus inflation model of cosmology for regions of space...
  26. MASmith

    Determining Planck's Constant With Photoelectric Effect

    Homework Statement I'm trying to determine Planck's Constant through an experiment with the Photoelectric Effect, however, the equations I'm given and the data I've collected are not getting me to the 6.63e-34 that I need to be at. I'm graphing Stopping Potential (V) vs 1/λ and then using the...
  27. 3

    Analyzing Planck Data for No-Scale Supergravity Inflation

    I apologize in advance if this is not the correct place to post this. I am currently writing a paper in no-scale supergravity inflation, and now that the Planck 2015 results are here, it would be nice to use them to constrain the parameters of the model. I am in particular interested in the...
  28. M

    It is said that we can not go lower than the planck limit

    Hi. My nephew asked me a good question. I am trying to understand the Planck limit. It is said that we can not go lower than the Planck limit. But if we had a an imaginary powerful microscope to see at the plank level, and if we placed 2 Planck end to end with "half" a Planck sized length...
  29. P

    Max Planck Institute For Physics

    What do you guys think of Max Planck Institute for Physics as a place for one to pursue PhD in theoretical physics? ny previous experience you can share?
  30. websterling

    Planckoscope- Visualizing Planck Data

    http://astrog80.astro.cf.ac.uk/Planck/Chromoscope/']I[/PLAIN] saw this referenced in a blog last week and thought it worthy of sharing. http://astrog80.astro.cf.ac.uk/Planck/Chromoscope/ It's built off of Chromoscope, an app for visualizing the sky in a range of wavelengths, but it uses...
  31. websterling

    Is the Diffuse Microwave Energy from Galaxies Contributing to CMB Measurements?

    The Planck 2015 (formerly 2014) Data Release will finally be released to the public tomorrow February 5. Details at- http://www.cosmos.esa.int/web/planck
  32. B

    E=hf as energy of a particle (other than photon)

    In de Broglie's matter wave equation, a book(namely Concepts of Modern Physics) derived the matter wavelength by putting ##E=hf## and ##E=\gamma mc^2## as equals. However I thought that ##hf## was energy of a photon, not a particle. Aren't these two very different concepts?
  33. P

    Question with respect to a Max Planck article

    This is not a homework problem, this is a question borne out of self-interest. I picked up the book "The Dreams that Stuff is Made of" by Stephen Hawking: (https://www.amazon.com/dp/0762434341/?tag=pfamazon01-20 ) and read the first article by Max Planck: "On the Distribution of Energy in the...
  34. S

    Questions Concerning The Planck Epoch

    Questions Concerning The Planck Epoch I must begin this thread with an apology. I am NOT a physicist nor astronomer; in fact, my degree is in biology. However, for decades I have had a deep interest in what is commonly referred to as Big Bang Cosmology and have an “educated layman’s”...
  35. J

    Find Physicists' Published Papers: Max Planck, Ludwig Boltzmann

    Does anyone have any suggestions for finding lists of all papers published by individual physicists? Usually the Google machine turns up hits pretty quickly, but I've hit a brick wall looking for lists for Max Planck and Ludwig Boltzmann. netlib.org/bibnet/ is amazing, but it's pretty narrow.
  36. D

    Interpreting E=hf: Particle, Wave & Planck's Constant

    I know what the letters mean, E = Energy of the photon, h = Planck's constant, f = frequency of the photon. But what does it mean for a particle to have a frequency, something that I'd associate with a wave. And what can you think Planck's constant is representing? Any replies would be much...
  37. K

    WMAP or Planck Maps (cartesian projection)

    Does anyone know where I might find WMAP and/or Planck maps of the dipole/quadrupole/octupole images that were done using the cartesian cylindrical projection? I've been able to find them in the standard Mollweide projection via Google images but can't seem to find any that were made with the...
  38. P

    Video: from Planck to Universe

    Hi. I wasn't sure where to post this, but wanted to share this amazing video. From the smallest to the biggest thing in the universe:
  39. G

    How can it be deduced general relativity from planck length

    How can it be deduced general relativity from Planck length?
  40. marcus

    New Planck mission results, Ferrara December 1-5

    So far a lot of the stuff from the December Ferrara conference is in French. Nice movie! http://videotheque.cnrs.fr/visio=4401 Neutrino news: http://public.planck.fr/resultats/250-ce-que-planck-dit-des-neutrinos Latest on dark matter...
  41. marcus

    ΛEPRL quantiz'n of cosmological horizon area in Planck units

    The ΛEPRL spin foam model presented 25 November at ILQGS by Haggard and Riello achieves an interesting quantization of the cosmological constant. Basically this is done on slide #10 around minute 15 of the audio. http://relativity.phys.lsu.edu/ilqgs/haggardriello112514.pdf...
  42. G

    Light & Electron Energy: Comparing Quantized Energies

    I was reading a section of a chemistry textbook describing electron energy shells. It compares the electrons to light saying that electrons energies are quantized and so are light energies. Electrons can only jump from one specific energy level to another with no intermediary energy levels. I...
  43. V

    Understanding Planck Scale Derivation: Energy, Length, and Uncertainty

    I see that Planck scale of mass-energy is related to the corresponding length scale by application of the uncertainty principle. What is not clear for me is how we find either energy or length scale to compute the other one? What goes wrong if we assume a higher energy level than the Planck...
  44. F

    Derivation of Planck Radiation Formula

    I am having some issues with the derivation of the Planck Radiation Formula, as for instance given in http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html . My point is that the assumption of cavity modes implies the formation of standing waves inside the cavity walls. In most situations in...
  45. nomadreid

    Assigning a Size to Particles and Strings: From Planck Scale to the Universe

    Except for associating a statistical mean to a large number of measurements, how can one assign a single point to a particle ? Indeed, how can one assign a size of anything less than the Planck scale? A similar question about strings: how can one talk about one-dimensional objects? A similar...
  46. B

    Speed of light and planck length

    I was thinking about the special theory of relativity and how as one approaches the speed of light, ones length contracts. what I would like to know is: If I had an object and I accelerated it towards the speed of light and it contracts in the direction of travel, what happens when it reaches...
  47. J

    Deriving the rayleigh-jeans limit of planck law of radiation

    Hello there, Plack law of radiation $$ B(\nu) = \frac{2\,h\,\nu^3}{c^2(e^{h\nu/kT}-1)} $$ I want to show that for small frequencies, Reyleigh-Jeans law: $$ B(\nu) = \frac{2\nu^2kT}{c^2} $$ is correct. I take the limit of Planck law as ##\nu \to 0## using l'hopital rule: $$ \lim_{\nu \to 0}...
  48. Chronos

    Planck dust modeling and BICEP2

    Planck dust modeling has been released [re: http://arxiv.org/abs/1409.2495] . It appears to be consistent with the assumptions of BICEP2, but, that is an unsupported assumption. I expected an immediate reaction from the BICEP2 team, or other interested parties. Perhaps I am merely impatient, or...
  49. marcus

    How would you explain Planck units to layman?

    Suppose you meet a layman who has not even had Freshman-level college physics, but who has HEARD of or read something about Planck units and is curious about them. How would you go about explaining? Maybe it's obvious to some people how to do it, or maybe you have already had that experience...
  50. D

    What happens when matter pops into and out of existence at Planck length scales?

    All - my first post, and as a lay person interested in quantum physics, forgive me if my questions are naive or ill-informed. Is it possible that the Universe inflated then exploded into being from a singularity smaller than Planck length? If I understand the concepts properly, the Planck...
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