20,253 reputation
3975
bio website mat.univie.ac.at/~neum
location Vienna, Austria
age
visits member for 3 years, 6 months
seen 16 hours ago

I am currently primarily active on Physics Overflow. Here I mainly respond to comments on my old postings, sometimes upon request by email, and sometimes because I happen to see an interesting question for which I know a quick but useful answer. Occasionally I also post purely mathematical questions.

Some physics material I wrote:

  • A theoretical physics FAQ
  • Classical and Quantum Mechanics via Lie algebras
  • Renormalization without infinities - an elementary tutorial
  • Classical and quantum field aspects of light
  • Optical models for quantum mechanics
  • Molecular modeling of proteins and mathematical prediction of protein structure


  • Aug
    26
    comment Definition of stress at the microscale
    Integrals over the stress tensor are extensive quantities and have in a thermodynamic setting integrals over the metric tensor as conjugate intensive quantities. See the book By Oettinger, Beyond equilibrium thermodynamics. - So probably the answer to your surface tension question is yes, after some slight smoothing of the stress tensor in a thin shell around the surface.
    Aug
    25
    answered Can quarks be considered elementary?
    Aug
    25
    answered Pressure and Temperature in a few-body system
    Aug
    25
    comment Does the axiom of choice appear to be “true” in the context of physics?
    @AbdelmalekAbdesselam: Why does AC have an ugly face? The problems inherited by and avoided by AC are well understood, and that there are problems only shows that once beyond the countable realm one has multiple notions of infinity, so that one can choose the more tractable one. Since the constructible model within any model of ZF satisfies ZFC, there cannot be anything wrong with the axiom.
    Aug
    23
    awarded  Revival
    Aug
    23
    revised Definition of stress at the microscale
    fixed grammar
    Aug
    21
    answered Definition of stress at the microscale
    Aug
    12
    awarded  Necromancer
    Aug
    3
    awarded  Popular Question
    Jul
    28
    answered Rest Mass and Wigner's Classification
    Jul
    25
    comment Lie algebra and Lie group about quantum harmonic oscillator
    My short and concise answer is at physicsoverflow.org/14831
    Jul
    25
    answered What is the defintion of a current-current diagram?
    Jul
    25
    answered In QFT are fields considered a property/function of spacetime? How do they become “excited”?
    Jul
    22
    revised What is the entropy of a mixed state in classical physics?
    added 76 characters in body
    Jul
    21
    comment What is the entropy of a mixed state in classical physics?
    @Yrogirg: I added to my answer a caveat concerning my proposed formula.
    Jul
    21
    revised What is the entropy of a mixed state in classical physics?
    added qualification
    Jul
    21
    comment Statistical analysis of data in Physics
    @vzn: I augmented my answer. You can specialize it yourself to casting dice, with the unreasonable prior being a Dirichlet prior with 100% probability for getting 6, weighted corresponding to 1000 events.
    Jul
    21
    revised Statistical analysis of data in Physics
    added an argument
    Jul
    20
    awarded  Necromancer
    Jul
    20
    awarded  thermodynamics