Understanding Shannon entropy: (1) variability within a distribution

Published 2020-07-27
In this series of videos we'll try to bring some clarity to the concept of entropy. We'll specifically take the Shannon entropy and:
* show that it represents the variability of the elements within a distribution, how different are they from each other (general characterization that works in all disciplines)
* show that this variability is measured in terms of the minimum number of questions needed to identify an element in the distribution (link to information theory)
* show that this is related to the logarithm of the number of permutations over large sequences (link to combinatorics)
* show that it is not in general coordinate independent (and that the KL divergence does not fix this)
* show that it is coordinate independent on physical state spaces - classical phase space and quantum Hilbert space (that is why those spaces are important in physics)
* show the link between the Shannon entropy to the Boltzmann, Gibbs and Von Neumann entropies (link to physics)


Most of these ideas are from our paper:
arxiv.org/abs/1912.02012
which is part of our bigger project Assumptions of Physics:
assumptionsofphysics.org/

All Comments (21)
  • @gcarcassi
    DISCLAIMER: If you see ads, these are put in by YouTube. I do not get any money from them, YouTube does. I'd like to turn them off, but it seems it's out of my control!
  • @koppanydodony8769
    Finally a great video on the topic. Thank you, I have been searching for this for long.
  • Great video. I am looking forward to watching the rest of the videos on information theory.
  • @AlbertFlor
    Incredibly clear and insightful explanation, thank you!
  • @hariprasadyalla
    Wonderful explanation. I struggled for a day to fully comprehend how the logarithmic part of entropy formula work when the probabilities are not exactly equal to some powers of a base b. The third property in this explanation made my day. Thank you so much.
  • @alijassim7015
    It's the first time I hear that there are different types/definitions of entropies... I always found entropy to be a challenging concept in itself; I think reading studying these different definitions might actually help me understand the concept better.. Thanks!
  • wow.. this was an incredible video! Entropy is something that I am always finding out new things about.. harder to understand than quantum mechanics if I am being honest..
  • ohhh i hear about shannon entropy being described as "information", "uncertainty", "surprise", and yeah they sound vague . the sources i got these from are mostly popular science content creators, meant to attract and introduce people to the field... so valuable to have deeper, meatier contents like this also
  • @vicvic553
    Thank you so much. It really brigthen my imagination a lot! But actually, how it is related in context of informational theory? Could you make a video or just simply explain using an example, please?
  • I'm trying to make examples: suppose we have a set O of three types of elements • × Δ , having 4 of those elements each. If we have other sets A,B,C with: A = { 8• , 2× , 2Δ } B = { 2• , 8× , 2Δ} C = { 2• , 2× , 8Δ } then all A, B, and C will have the same shannon entropy, and all of them will have shannon entropy larger than the original set O?
  • @nidhibhawna2176
    Please make a video on How to use Shannon entropy to detect land-use change.
  • @sukursukur3617
    5:12 zscore helps for grouping numbers as independent from their values in the set. But if the data is continuous, it doesnt work.
  • @EinSofQuester
    what I don't understand is how come we're using the full H(pi) when breaking down the shannon entropy into it subtypes. Why are we doing H(rk) = H(pi) + pa(H(qj)) instead of only using the portion of H(pi) which is not also included in H(qj)?
  • @jameschen2308
    Where can I read up on entropy in the style of how you presented it?