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Jan
26
awarded  Yearling
Jan
18
comment Entropic force in rubber bands
Yep,those forces also arise from entropy maximization at finite temperature.
Jan
16
answered Entropic force in rubber bands
Jun
9
comment What do up-left orthogonality has in common with up-down and what is their relationship?
Please reread my earlier comments.
Jun
9
comment What do up-left orthogonality has in common with up-down and what is their relationship?
Linear algebra is a common framework. A Hilbert space is an inner product space. The link is mathematical, not physical.
Jun
9
comment What do up-left orthogonality has in common with up-down and what is their relationship?
To further clarify, consider instead the quantum states of a simple massive spinless particle in a box. The physical space has no vectors to speak of, and so there is no orthogonality in their spatial configurations to worry about. But the Hilbert space of states (ground state, first excited state, etc.) still admits a notion of orthogonality. It is that sense of orthogonality that applies to the spin configurations you ask about too.
Jun
9
comment What do up-left orthogonality has in common with up-down and what is their relationship?
You misunderstand in which space these are orthogonal. Up and down spin configurations are orthogonal in the Hilbert space of states. Yes, this Hilbert space is describing the possible configurations of a vector (or spinor) in physical space, and there is also a notion of orthogonality in that space, but it is in the Hilbert space of states where up and down spin configurations are considered orthogonal. Does that help?
Jun
7
answered what is the combined partition function of two similar but independent systems?
Jun
7
comment Physics of donut magnets levitating vertically on a pencil?
Here's a related question: consider a chain (or any other rope whose linear mass density is non-negligible) suspended from the ceiling with lower end free. What is the tension on this chain as a function of the distance from the ceiling?
Mar
21
awarded  Enlightened
Mar
21
awarded  Nice Answer
Feb
6
accepted Low-energy gluodynamics as a string
Jan
26
awarded  Yearling
Oct
5
revised Scale invariance symmetry as a simple argument in an electrostatics problem
deleted 17 characters in body
Oct
5
answered Scale invariance symmetry as a simple argument in an electrostatics problem
Aug
28
answered What happens when you shake a can of soda?
Jul
1
awarded  Mortarboard
May
16
comment Massless charged particles
To be precise, you need to turn your partial derivatives into covariant derivatives to minimally couple the scalar the field to the photon field: $\mathcal{L} = D_\mu\phi^\ast D^\mu\phi$ for $D_\mu = \partial_\mu + ie\hat{Q}A_\mu$. From here, note that the photon-loop diagram would give a mass renormalization. Unless there is some symmetry which protects/prevents the renormalization of the $\phi$ field's mass, there is no reason to assume that this bare Lagrangian should give physically massless particles!
Mar
23
answered Is a charged particle at rest affected by magnetic field?
Mar
21
revised How exactly is the propagator a Green's function for the Schrodinger equation
added 1 characters in body