Comments by "Lepi Doptera" (@lepidoptera9337) on "Stanford" channel.

  1. Yes, you are totally wrong. :-)
    3
  2. Because the universe is homogeneous. See Noether's Theorem.
    2
  3.  @waynelast1685  You can't look up Noether's Theorem on the internet or in the library? That's very intellectually lazy of you. :-)
    2
  4.  @waynelast1685  So you know or you don't recall? You sound like you are on drugs, right now. :-)
    2
  5. A photon is a little bit of energy. Asking for its size is like asking "How big is a kWh?". If the latter doesn't make sense to you (and I hope that it doesn't), then asking for the size of a photon does not make sense, either.
    2
  6.  @waynelast1685  A visible photon is a few eV in energy. So, if that energy has a size, then how big is a kWh? :-)
    2
  7.  @waynelast1685  I know exactly what you are thinking. :-)
    2
  8.  @waynelast1685  I wasn't wasting your time. I made it pretty clear that I think that you are nothing but a poorly performing troll, didn't I? :-)
    2
  9.  @waynelast1685 See my first post. :-)
    2
  10. The only physics courses worth going to in college\university are those for physicists. Forget about "Physics 101 for x", where x is in {engineers, mathematicians, chemists, egyptologists, dentists, podiatrists, pre-school teachers,...}. I had desperate students from other faculties come to me because they couldn't understand the material. They showed it to me... and I couldn't understand it THAT WAY, either. Physics can not be abbreviated. There is a reason why physicists take an entire semester just for something fairly straight forward like classical mechanics... and in reality it would have to be two to get to any substantial level. So, yeah, it's not "you". It's the way they are trying to teach it to you.
    2
  11. Why is Stanford inviting bullshitters????
    2
  12.  @waynelast1685  I don't like people on drugs. That's pretty much mainstream. :-)
    1
  13. They have to do with the Fourier transform of a rectangular aperture. If we chose gentle slopes, the fringes go away. That Fourier transform of a Gaussian is a Gaussian. The Fourier transform of a rectangle is a sin(x)/x (sinc) function. It's a mathematical rather than a physical effect.
    1
  14. Wow, that was a big pile of bullshit. ;-)
    1
  15.  @SpotterVideo  Dude, science doesn't work by listening to people who had lost their minds, already. It works by listening to nature. Absolutely nothing about quantum mechanics is even borderline "crazy". It is actually quite trivial once you know what you are looking at.
    1
  16.  @SpotterVideo  Planck's constant is 1 in every rationally chosen system of physical units. What's the source of angular momentum quantization? Relativity. You can find the derivation of relativistic quantum fields as representations of the Poincare group in suitable QFT textbooks.
    1
  17.  @SpotterVideo  We start with the Poincare group and then we derive all possible equations of motion that are compatible with it from symmetry principles. Those include classical laws like Maxwell and then it includes the quantum fields of the standard model. The classical laws don't produce universes with matter. There will be no chemistry, no nothing in those. Leaves the ones with h=1. That's universes based on quantum fields. They happen to reproduce all the visible effects. The actual number is based on our choice of the length of the meter and second and the size of the kg. If we chose different base units we can make h=c=1. The only physical constants that we can not reduce to one are the unitless ones like the fine structure constant, which is roughly 1/137 no matter how we chose the units. Why is it that value? Because not all combinations of quantum fields produce self-consistent converging theories. Which do and which don't depends on physics that is currently out of our reach experimentally. That's why people are searching for e.g. supersymmetric fields. They would complement the currently known ones in ways that should explain why it is this particular universe and not some other. And, no, you don't have a model until you can quantitatively reproduce all known phenomena. And that you can't. At this point all you have is bullshit. ;-)
    1
  18.  @SpotterVideo  Yes, I am familiar with bullshit. You don't have to create more than you already have. ;-)
    1
  19.  @SpotterVideo  I know that you are throwing random words at a wall to see what sticks using bullshit as a gluing agent. ;-)
    1
  20.  @SpotterVideo  And there is the lonely kid who feels sorry for himself because an adult isn't taking him seriously. ;-)
    1
  21. Yes, it is, and you should avoid it like hell. Why? Because depending on the implementation you may run into machine limitations that you would never suspect to exist. Moreover, it's extremely hard to debug a recursive function that is 124,000 calls deep. Why would you do that to yourself? A billion iterations of a loop is still the same loop operating on the same one copy of the data, but 124,000 recursive function calls are operating on 124,000 copies of the data. You really want to check all of them? Really? ;-)
    1
  22. He is a theoretical physicist. To him c=1, which is the rational choice. The speed of light is not a meaningful physical constant.
    1
  23. Says the valet parking runner? ;-)
    1
  24. What this says is that your life would have been exactly the same. Most of this material was fully accessible in libraries 40 years ago. Did you care to go in there and look?
    1
  25.  @pklausspk  Libraries can get books from other libraries, you know.
    1
  26. That's because he is not talking to a general audience. He is talking to highly intelligent students here. :-)
    1
  27. He has some good points, but at the end of the day everybody "programs in C" because what we want from a program are the side effects, i.e. the execution of the functions. It doesn't matter how we package these functions and how we call them. The goal of programming is always about an algorithm to solve a problem (and solving that problem is the actual goal, but never mind that). What makes this a quality class is that he is teaching you what the compiler does with your code, because that is important, no matter which paradigm you use and in what language you write. This looks like a much better class than some others I have seen (even from Stanford professors).
    1
  28. If they don't teach this now, then they are not teaching you well. ;-)
    1
  29. Well, that's for sure how my parents created highly intelligent life. Sorry that yours had to use in-vitro fertilization and ended up with less than optimal results. ;-)
    1
  30. Relative to what?
    1
  31. Many people struggle with subtle concepts. I remember some kids in my high school physics classes who were absolutely out of touch with the material. They weren't even the least performing kids. Some were quite artistic. Some, of course, become obsessed with "proving physics wrong".
    1
  32.  @davidhand9721  Yes, then there are the folks who want to prove Einstein wrong... Coming back to school, I remember one girl nearly started crying because she couldn't understand harmonic motion. It was one of the few times that I thought that we are teaching high school poorly. Or maybe there really are such large differences between individual people's brain structure that they can't be overcome even by refined teaching methods. There is, for sure, a real problem here as society becomes ever more dependent on ever more complex science.
    1
  33. You should publish that. ;-)
    1