Recent content by Negatratoron

  1. Negatratoron

    Addition of moments of inertia

    Can you draw a picture of what you're asking? Generally the moment of inertia of a body about an axis is ##\int r^2 dm## where ##r## is the distance to the rotational axis and ##dm## measures the mass of the object. This is equal to ##\iiint_V r^2 \rho(x,y,z) dx dy dz## where ##V## is the...
  2. Negatratoron

    I Uncertainty between position and angular frequency - is this correct?

    Thank you for telling me so. I finally take quantum next semester, so I'll be able to crawl out of the quagmire of self-taught sorcery and onto the dry land of firm, practical foundations.
  3. Negatratoron

    I Uncertainty between position and angular frequency - is this correct?

    Motivation: In my thermodynamics + statistical physics class, we derived the equipartition theorem for ideal gasses using Boltzmann factors, dividing the phase space of a gas particle in position+momentum space into units of size x*p=h based on the quantum nature of the space of states that are...
  4. Negatratoron

    Can an object be halfway between focal point and diverging mirror?

    I think I figured it out. Table 33.2 in the text has a footnote in the "o < 0" case: "Encountered only with lens or mirror combinations". If any mirror is in combination with other mirrors and lenses, it may be the case that the object is behind the mirror.
  5. Negatratoron

    Can an object be halfway between focal point and diverging mirror?

    A physics question from Principles of Physics by Mazur in the chapter on Optics is asking me to "repeat Problem 92 for a diverging mirror", and one of the questions in Problem 92 (which is about a converging mirror) is to find the image distance of an object halfway between the focal point and...
  6. Negatratoron

    Discussion Thread on the "Massless Charge" Perpetual Motion Machine

    Imagine a massless (or very light-weight) charge that is glued to a rod undergoing sinusoidal motion along an axis. The acceleration of this charge produces electromagnetic waves, which can be harvested for energy, and this energy can be used to power the continued sinusoidal motion as well as...
  7. Negatratoron

    Comp Sci C++ Reading Data File: Calculating Distances and Finding Closest Point

    Oh, and instead of initializing minval to std::numeric_limits<double>::max(), you can initialize it to std::numeric_limits<decltype(minval)>::max() for more stable code. If you change the type of minval to float, or to a higher-precision fractional type, then you won't have to also change the...
  8. Negatratoron

    Comp Sci C++ Reading Data File: Calculating Distances and Finding Closest Point

    The latest code you posted has several problems. First, you declare the variable distances as double distances[1] but later you set distances[i] = ... for ##1 <= i < 1000##. I'm guessing you wanted to declare double distances[MAXI] instead, so that you do not overrun the array bounds...
  9. Negatratoron

    B What constitutes a measurement of which slit - double slit

    Thanks, that's a good PDF. Let's say you have a device, and you're not sure whether or not it detects photons. Can you test it by putting it in front of one slit, and checking whether there's interference? It sounds like you could...
  10. Negatratoron

    B What constitutes a measurement of which slit - double slit

    You know, it seems like the reason the film would not constitute a measurement, is because you actually can't use it to tell which slit any given photon passed through. The slit-detection apparatus makes a difference because it increases sensitivity.
  11. Negatratoron

    B What constitutes a measurement of which slit - double slit

    What materials were actually used to conduct the two-slit experiment? I feel like my misunderstanding comes from using these ideal abstractions like "film" etc.
  12. Negatratoron

    B What constitutes a measurement of which slit - double slit

    Consider just the film (or other sensing device). If each photon brightens a certain area, doesn't that alone constitute a measurement of which slit it went through?
  13. Negatratoron

    B What constitutes a measurement of which slit - double slit

    In the double slit experiment, when you measure which slit your photon passes through, it will land in the corresponding location on the photosensitive film at the end of the apparatus. If, however, you don't measure which slit it goes through, an interference pattern will appear on the film...
  14. Negatratoron

    Non-technical description of "superposition"

    Interesting; I'm going to need to read up on Bell's inequality. Point 3 is very interesting - I didn't know "superposition" and "observer" would be considered part of interpretations of QM, rather than QM itself. (I think I consider interpretations to be meta-physics. And you know what they...
  15. Negatratoron

    Non-technical description of "superposition"

    Context of this post (skim or skip, but read the last paragraph): I like to teach things to people, especially those who believe that they won't understand. For those hard cases you almost have to trick them into learning something. That is, just start building up concepts in simple terms...
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