Qmechanic's user avatar
Qmechanic's user avatar
Qmechanic's user avatar
Qmechanic
Moderator
  • Member for 11 years, 7 months
  • Last seen this week
130 votes

Why can't $ i\hbar\frac{\partial}{\partial t}$ be considered the Hamiltonian operator?

114 votes
Accepted

Is spacetime flat inside a spherical shell?

74 votes
Accepted

Why treat complex scalar field and its complex conjugate as two different fields?

70 votes
Accepted

How do I construct the $SU(2)$ representation of the Lorentz Group using $SU(2)\times SU(2)\sim SO(3,1)$ ?

65 votes

Don't understand the integral over the square of the Dirac delta function

52 votes
Accepted

Why are Only Real Things Measurable?

48 votes
Accepted

Does Heisenberg's uncertainty under time evolution always grow?

46 votes

Is the converse of Noether's first theorem true: Every conservation law has a symmetry?

43 votes
Accepted

Gauge covariant derivative in different books

41 votes

Is there something similar to Noether's theorem for discrete symmetries?

40 votes
Accepted

Do an action and its Euler-Lagrange equations have the same symmetries?

38 votes
Accepted

Deriving the Lagrangian for a free particle

38 votes
Accepted

Lagrangian and Hamiltonian EOM with dissipative force

37 votes
Accepted

Why do we use Hermitian operators in QM?

35 votes
Accepted

Why is the contribution of a path in Feynmans path integral formalism $\sim e^{(i/\hbar)S[x(t)]}$?

33 votes

What does the Canonical Commutation Relation (CCR) tell me about the overlap between Position and Momentum bases?

32 votes
Accepted

Reason for the discreteness arising in quantum mechanics?

32 votes
Accepted

What symmetry causes the Runge-Lenz vector to be conserved?

32 votes
Accepted

The formal solution of the time-dependent Schrödinger equation

32 votes
Accepted

Which transformations are canonical?

31 votes
Accepted

Why can't d'Alembert's Principle be derived from Newton's laws alone?

31 votes
Accepted

How to derive Maxwell's equations from the electromagnetic Lagrangian?

31 votes

Is there a proof from the first principle that the Lagrangian L = T - V?

31 votes

Why do all fields in a QFT transform like *irreducible* representations of some group?

30 votes

Hilbert space of harmonic oscillator: Countable vs uncountable?

30 votes

Quantization of a particle on a spherical surface

30 votes
Accepted

Why the statement "there exist at least one bound state for negative/attractive potential" doesn't hold for 3D case?

30 votes

What is the connection between Poisson brackets and commutators?

29 votes

Is there a kind of Noether's theorem for the Hamiltonian formalism?

29 votes

$\lambda=\frac{2h}{p}$ instead of $\lambda=\frac{h}{p}$?

1
2 3 4 5
123