Recent content by rainbowings

  1. R

    Magnet Properties: Stick to Steel at 150°C?

    A distribution ain't a function! A distribution is just a record of which values of the variable in question are how probable. Now, the (random - so to say) variable itself could depend on some other parameter - say time. Then the distribution itself becomes a function of time. So at each...
  2. R

    Textbooks on Condensed Matter Physics

    i think marder complements ashcroft and mermin in several ways - especially, in being more up to date and experiments-friendly. however, i do think it is much more loosely written - ashcroft and mermin takes the cake for rigor. in my experience, kittel is irritating if you are looking for...
  3. R

    The famous Institute of Theoretical Physics?

    two in the US come to my mind immediately: ITP - Princeton KITP - UCSB
  4. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    galileo ...i completely agree - the above statement was just FYI for wizzart. adi
  5. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    The alzebra is right, but pray how does it answer the question one way or the other? Does the spin flip? Or does it not?
  6. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    The operation of measurement is represented by the operation of a projection operator on the state.
  7. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    How is Sz represented by this ket? What is the V-th postulate (so called von Neumann projection postulate)? Why is it necessary here?
  8. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    It makes perfectly good sense to represent the basis states of the 2D Hilbert space of spin half particles by ANY two linearly independent 2-D vectors (or dual vectors). The representation of the vectors can be perfectly legitimately made in terms of EITHER kets (column vectors) or bras (row...
  9. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    Resolution: 1) Observables are indeed represented by Hermitian operators. 2) The operation of Sx on Iz up> (excuse the notation) can be studied in ANY basis of your choice. a)Let's do what you did first - use the Sz basis. Then Sx is the Pauli_x matrix multiplied by hbar/2 and Sz is...
  10. R

    Can the Spin of an Electron Flip in a Different Direction than Measured?

    Here are some basic facts (that don't need checking): On observable is always represented by a Hermition Operator. The Hermitian nature of the operator does NOT care for which basis you expand the operator in (for your own convenience). In terms of matrices Hermitian means - take an element...
  11. R

    Understanding Glass: Is it a Solid or Liquid?

    maybe i m missing the context ... but glass IS a liquid. a very viscous one and one that requires nonequilibrium statistical mechanical description.
  12. R

    True Explanation of a Lever please.

    comments: N's theorem proves that corresponding to every continuous symmetry of the hamiltonian , there exists a conserved (not invariant) "charge" - i.e. a quantity that satisfies a continuity equation. (4 divergence = 0). It also explicitly constructs this charge for a given symmetry...
  13. R

    0/0 Anything divided by zero is undefined

    talking of horses, here's one way of understanding what's going on in terms of apples and oranges - if you had 10 apples and wanted to give an equal no. of them to 5 people, then the number of apples each one gets is 10 /5 =2 oranges. Extending this, if you had 0 oranges and wanted to give an...
  14. R

    Bloch Functions: Explaining the Bloch-Floquet Theorem

    Here's an insight into Bloch's theorem that most texts do not mention: The idea is that in a period potential, the probablilty of finding an electron at some location should be equal to the probablity of finding the electron at all other places which are identical due to periodicity- and this...
  15. R

    Books on Relativity: No Math Needed

    anything that explains special and general relativity without math can at best be a pop science book. if you want something that gets you started with no more than high school alzebra, look at relativity by resnick. my favourite is the book by taylor and wheeler. both deal with special...
Back
Top