Search results

  1. S

    I Assigning a value for integrating a divergent oscillatory function to infinity

    Is there any sort of equivalence between the Laplace transfrom method and the Cesaro method? Or can they sometimes give different answers?
  2. S

    I Assigning a value for integrating a divergent oscillatory function to infinity

    Yes!! The last section (Cesaro summability of an integral) is exactly the kind of idea I was trying to articulate. Thank you.
  3. S

    A Real image of a sawtooth standing wave in a musical string?

    In the video link I posted in post #26 if you watch the video from 04:14, the sine wave is flipping sign about twice a second, i.e. ##\pm sin(x)## This can't be a camera (sampling) artefact, I think? If not... well, normally one would expect the envelope of the string to be a surface of...
  4. S

    A Real image of a sawtooth standing wave in a musical string?

    If you want to really geek out on this subject: www.youtube.com/watch?v=nP1elMR5qjc BTW, how do you show the video link with a thumbnail and the "Click to expand..." ?
  5. S

    Wood/Glass/Metal Using a hand saw with ratchet-like teeth

    Fleam... rake... kerf... swarf... You have to love words like that, harking back to the days of the artisans' guilds. Will there be a time when people will say, "you have to love those old words like 'hopefully', 'ongoing' and 'actionable' " ?
  6. S

    Mathematical Model finds Acoustic Signal that May Predict Earthquakes

    Re. the singing sand dunes (previous post)... Some key inputs from the article: Can we apply dimensional analysis to connect the ~ 300 micron sand size to the ~100 Hz frequency, and thus get some clue about the kinds of things that may be going on? How can we get the latter order of magnitude...
  7. S

    Mathematical Model finds Acoustic Signal that May Predict Earthquakes

    A related phenomenon? https://www.nationalgeographic.com/news/2012/10/121031-singing-sand-dunes-physics-science-whistling/
  8. S

    A Real image of a sawtooth standing wave in a musical string?

    This may be a bit tangential from the OP. And yet...
  9. S

    A How can we derive the results that we know about QM from QED?

    Since I haven't learned anything about QED, I can't follow much of the above. But here's a naive question: there is a physical quantity (I don't recall which) that has famously been measured to some 20 decimal places, and it agrees with QED predictions to nearly the same precision. And this...
  10. S

    B A proper comprehensive rule for arithmetic operation precendence

    And as we all know, mankind will run out of electrons by 2073, even if we halve our current :cool: rate of consumption.
  11. S

    Mathematical Model finds Acoustic Signal that May Predict Earthquakes

    The high-tech version of an ominous creak in the timberwork. It might be interesting to listen to an audio version of the signal, with the playback speed suitably adjusted for human hearing. They may have provided the raw data under "supplemental material"...
  12. S

    I Assigning a value for integrating a divergent oscillatory function to infinity

    I needed to look up the residue theorem, which I have done and got some very basic understanding. I'm also trying to understand the properties of ##f(z)=z^{(a+ib)}##. For example, with a+ib = 1 + 5i there is a discontinuity along the negative real axis. Is this the reason that we say ##f(z)##...
  13. Making STRONG shelves with Topology Optimization

    Making STRONG shelves with Topology Optimization

    A project, that's fun, educational, cool-looking and actually useful! What more could you want? We're making topology-optimized floating shelf brackets today...
  14. S

    Mathematica Wolfram Cloud Notebook : Indenting Code

    I tried adding spaces manually to indent a multiline code block in a notebook on Wolfram Cloud (www.wolframcloud.com). It throws the "Set: Tag Times" error. How can I indent code lines (preferably manually, but auto will also be fine).
  15. S

    I Assigning a value for integrating a divergent oscillatory function to infinity

    Perhaps "meaningful" is not the best term here. In the case of divergent sums, Hardy uses words like "reasonable" and "natural". So speaking very loosely, a procedure for which one can claim that it is the summation of a divergent series in some justifiable sense*, and which yields the correct...
  16. S

    I Why randomness means incomplete understanding

    That reminds me of this implementation of an external random source: www.youtube.com/watch?v=1cUUfMeOijg where they claim to be using a video camera watching a lot of lava lamps to generate random keys. Any thoughts about this -- is it serious technology, or is it just their PR people doing a...
  17. S

    JavaScript How does pasting an image work, e.g. when composing a PF post?

    I have pasted the image below after copying it from my desktop. The image becomes visible in the Post Composer as soon as you paste it. It also works if you copy from another web page. I assume that JavaScript is able to grab the data from the clipboard and create an IMG element on the fly, and...
  18. S

    I Assigning a value for integrating a divergent oscillatory function to infinity

    There are meaningful ways to assign values to things like 1 - 1 + 1 + ... or 1 - 2 + 3 - 4 + ... In a similar spirit, is it possible to assign a value to the integral of a function like this: ##f(x)=x*sin(x)## or this one: ##g(x)=Re(x^{1+5i})## (Integrals from some value, say zero...
  19. S

    Appliances Faulty DeWalt Battery charger for power tools

    Well, you could make one of those "my crazy neighbor" videos for YouTube and quite possibly go viral.
  20. S

    Collection of Lame Jokes

    But why clay? I can't believe the fraudsters chose clay just to make this joke possible. If I want to put something into a box to simulate the heft of a phone, what's my most logical choice?
  21. S

    Wood/Glass/Metal Using a hand saw with ratchet-like teeth

    Hi all, I just got home and decided to have a go with a bit of scrap wood, keeping these suggestions in mind. I'm doing a lot better than before! Not pressing down too much seems to be a key point, plus getting the right angle between blade and surface (ideally, close to 0 degrees). In fact, I...
  22. S

    Wood/Glass/Metal Using a hand saw with ratchet-like teeth

    Yes, mine is pretty much like this one, but probably with the teeth more closely spaced (unless this one is really small). Thanks for all the replies, everyone... I'll try to apply the suggestions.
  23. S

    Wood/Glass/Metal Using a hand saw with ratchet-like teeth

    I tried to saw a piece of wood with a hand saw. Its teeth have an unsymmetric, ratchet-like bias that allows you to pull the saw, but they dig into the wood and refuse to move when you push. (This is not about the blade sticking in the gap after cutting halfway -- I can't even cut a couple of...
  24. Bernoulli! Bernoulli!

    Bernoulli! Bernoulli!

    Everyone likes to shout "Bernoulli!"
  25. S

    Collection of Lame Jokes

    English: "Publish or perish". German: "Papiere, bitte".
  26. S

    I What is the Meaning of the Schrödinger Equation?

    What did EPR add to the pot that wasn't there before?
  27. S

    I What is the Meaning of the Schrödinger Equation?

    I think it's both. But I'm not very sure. Edit: Of course, an experiment probably wouldn't be on a light year scale, but just big enough to prove faster-than-causal correlations. (In a sense, it is a correlation -- an anti-correlation, actually)
  28. S

    I What is the Meaning of the Schrödinger Equation?

    Sometimes this idea is introduced with a simple thought experiment: If a source emits a single photon with equal amplitudes in all directions, and if a detector catches it, say one second later, then the rest of the universe knows instantly that the photon is gone, and that no detector has any...
  29. S

    I Where to publicise some notes on quantum mechanics

    It's been a few months since your original post... I'm wondering what your final decision was. If haven't settled on a solution yet, here's a suggestion: You could submit it as a tutorial on PF's Insights blog, maybe working with a mentor to ensure that it is accurate. Based on the article...
Top