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self.grassmanian
  • Member for 6 years, 5 months
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372 votes
7 answers
56k views

Did the Big Bang happen at a point?

179 votes
2 answers
27k views

Why do we not have spin greater than 2?

  • 2,723
65 votes
4 answers
6k views

From where (in space-time) does Hawking radiation originate?

  • 32.6k
56 votes
5 answers
19k views

What does it mean for a Hamiltonian or system to be gapped or gapless?

  • 1,443
45 votes
10 answers
5k views

Are vacuum fluctuations really happening all the time?

  • 2,950
42 votes
4 answers
4k views

How does Fermat's principle make light choose a straight path over a short path?

35 votes
8 answers
4k views

Interval preserving transformations are linear in special relativity

  • 3,482
30 votes
2 answers
10k views

Basic questions in Majorana fermions

  • 2,339
29 votes
4 answers
4k views

Is there a way to split a black hole?

  • 14k
24 votes
2 answers
13k views

Differences between symmetric, Hermitian, self-adjoint, and essentially self-adjoint operators

  • 5,976
23 votes
2 answers
717 views

What is the analog of the Aharonov-Bohm effect for general gauge fields and for gravity?

22 votes
1 answer
4k views

When one discusses the "boundary" of Anti-de Sitter space, what do they mean precisely?

  • 3,252
22 votes
2 answers
3k views

Virtual particles and physical laws

  • 1,766
22 votes
1 answer
1k views

How did we know that the Dirac equation describes the electron but not the proton?

  • 95.5k
21 votes
4 answers
5k views

Gelfand-Yaglom theorem for functional determinants

21 votes
5 answers
5k views

How does QFT help with entanglement?

  • 381
20 votes
2 answers
4k views

What is "Dynamical phase transition"?

  • 1,018
19 votes
6 answers
2k views

Is the harmonic oscillator potential unique in having equally spaced discrete energy levels?

  • 6,020
18 votes
1 answer
4k views

What is so topological about topological phase transitions?

  • 1,681
15 votes
3 answers
2k views

Why does the Coarse-grained Entropy increase?

  • 483
14 votes
3 answers
2k views

Is ground state and vacuum state the same thing?

  • 329
14 votes
1 answer
3k views

Counting degrees of freedom for gravitational waves as a gauge field

14 votes
4 answers
6k views

Counting Degrees of Freedom in Field Theories

  • 902
12 votes
3 answers
1k views

What do physicists mean by an "integrable system"?

  • 95.5k
11 votes
1 answer
587 views

Why should there be one-particle states in an interacting quantum field theory?

11 votes
4 answers
3k views

Homogeneity of space implies linearity of Lorentz transformations

11 votes
2 answers
2k views

How do I define time-ordering for Wightman functions?

  • 5,943
10 votes
1 answer
2k views

What is the general procedure for constructing the Penrose diagram for an arbitrary $(1+1)d$ spacetime?

  • 41.8k
10 votes
1 answer
1k views

't Hooft vs ABJ anomalies [closed]

9 votes
1 answer
2k views

How can a find the symmetry group of a Lagrangian?