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N.S.
  • Member for 7 years, 2 months
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199 votes
9 answers
255k views

If photons have no mass, how can they have momentum?

  • 2,656
164 votes
11 answers
16k views

What makes a theory "Quantum"?

151 votes
8 answers
18k views

Is $\pi^2 \approx g$ a coincidence?

  • 1,295
116 votes
8 answers
35k views

What is $\Delta t$ in the time-energy uncertainty principle?

  • 1,185
114 votes
14 answers
28k views

QM without complex numbers

  • 3,146
101 votes
4 answers
9k views

Why does nature favour the Laplacian?

  • 1,157
99 votes
14 answers
43k views

About the complex nature of the wave function?

  • 4,572
84 votes
3 answers
9k views

Can photons be detected without being absorbed?

  • 841
78 votes
3 answers
8k views

What does general relativity say about the relative velocities of objects that are far away from one another?

78 votes
1 answer
9k views

Does Feynman's derivation of Maxwell's equations have a physical interpretation?

76 votes
4 answers
14k views

If a mass moves close to the speed of light, does it turn into a black hole?

  • 871
64 votes
8 answers
147k views

Why doesn't the frequency of light change during refraction?

59 votes
3 answers
24k views

What is the difference between implicit, explicit, and total time dependence, e.g. $\frac{\partial \rho}{\partial t}$ and $\frac{d \rho} {dt}$?

54 votes
2 answers
5k views

Does entropy depend on the observer?

  • 3,546
50 votes
4 answers
22k views

The meaning of action

  • 1,187
48 votes
5 answers
127k views

In electrostatics, why the electric field inside a conductor is zero?

  • 16k
46 votes
6 answers
29k views

Difference between spin and polarization of a photon

  • 4,275
45 votes
4 answers
3k views

Does quantum mechanics violate the equivalence principle?

  • 6,026
44 votes
7 answers
8k views

If the ground's normal force cancels gravity, how does a person keep rotating with the Earth?

  • 1,227
41 votes
4 answers
21k views

Book covering differential geometry and topology for physics

38 votes
3 answers
2k views

Not all self-adjoint operators are observables?

37 votes
7 answers
4k views

Can one do the maths of physics without using $\sqrt{-1}$?

  • 457
33 votes
5 answers
5k views

If two sound waves that are different frequencies create beats that occur several hundred times per second, can you hear this effect as its own tone?

  • 445
31 votes
5 answers
28k views

What is the physical meaning of the affine parameter for null geodesic?

  • 4,754
31 votes
4 answers
7k views

Why aren't the energy levels of the Earth quantized?

  • 1,403
29 votes
4 answers
3k views

Why doesn't the phase operator exist?

  • 645
29 votes
10 answers
5k views

Why is the fundamental postulate of statistical mechanics true?

28 votes
1 answer
3k views

What situations in classical physics are non-deterministic?

  • 3,122
28 votes
3 answers
3k views

Would every particle in the universe not have some form of measurement occurring at any given time? [duplicate]

  • 507
28 votes
4 answers
9k views

Speed of light in a gravitational field?

  • 896