Recent content by pines-demon

  1. P

    Praise 2025 PF Member Awards Ceremony

    Glad to see many of my votes made it to the list and happy to discover users I did not know. Happy new year to everybody.
  2. P

    Stirring Coffee Effectively

    There is a whole discussion in coffee media if one should swirl or stir (but is mostly related to getting an homogeneous espresso and is it not about sugar).
  3. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    Try Fetter&Walecka or Coleman.
  4. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    Look at this notes from Berkeley: https://bohr.physics.berkeley.edu/classes/221/1112/notes/timerev.pdf They do the usual time-reversal operator properties in first quantization and why it acts like a complex conjugation. Note they are careful to never write ##H^*## or for any operator. I think...
  5. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    But this ##H## still seems like an operator what does ##\nabla_r^*## mean?
  6. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    Please copy the Hamiltonian here to understand your question better.
  7. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    For that your Hamiltonian has to be diagonal in ##q##. Also you are assuming properties of ##\Theta## if not I don't get how are you getting the complex conjugate, maybe I am missing a step.
  8. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    Sorry this gets confusing because we mix various stuff in second quantization, your ##H## is in some basis, let me use hats for operators. When I write ##H(\mathbf k)## I mean that you can write the usual Hamiltonian as ##\hat H=\sum_k \hat{c}^\dagger_k H(k) \hat{c}_k## with some creation...
  9. P

    Graduate Two equivalent statements of time reversal symmetric Hamiltonian

    Be careful, what is the argument? If you write ##H(t)## or ##H(\mathbf r)## it is not the same as ##H(\mathbf k)## (##\mathbf k## being the momentum/wavenumber). In Fourier space ##H(-\mathbf k)=H^*(\mathbf k)## is an equivalent condition to time-reversal invariance.
  10. P

    Undergrad Before the Big Bang

    I do not know if this has been brought out. There is this theory of Janus universes (as in Janus the god with two heads). Where basically from point ##t=0##, going forward in time gives a universe and rewinding back gives another universe. Similar to putting many gas particles in the corner of a...
  11. P

    Undergrad Valid local explanation of Bell violations? (Pegg et al., 1999; 2008)

    To be clear, I agree with you.
  12. P

    Undergrad Valid local explanation of Bell violations? (Pegg et al., 1999; 2008)

    I still do not know what this is all about. All his proofs are.
  13. P

    Undergrad Valid local explanation of Bell violations? (Pegg et al., 1999; 2008)

    I do not know what this has to do with anything I said. Nevertheless, it is important to point out that Bell clarified this nonlocality in his later proofs of his theorem. His first paper has some assumptions that he ditched out later (but he always referred to that nonlocality).
  14. P

    Undergrad Valid local explanation of Bell violations? (Pegg et al., 1999; 2008)

    It is, it is retrocausality. You might say it is "local" if you wish but you are still breaking causality which seems as or more problematic than "nonlocality" (whatever that means).
  15. P

    Graduate Predictions for the Nobel Prize in Physics 2025 (results: John Clarke, Michel H. Devoret and John M. Martinis)

    See post before yours.