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36 votes

4 answers

4k views

Why do we need complex representations in Grand Unified Theories?

asked Apr 27, 2015 at 12:31

30 votes

6 answers

8k views

Noether Theorem and Energy conservation in classical mechanics

asked Jan 19, 2014 at 17:46

28 votes

2 answers

11k views

Dirac spinors under Parity transformation or what do the Weyl spinors in a Dirac spinor really stand for?

asked Nov 16, 2014 at 13:29

26 votes

2 answers

10k views

Connection between conserved charge and the generator of a symmetry

asked Sep 27, 2014 at 10:07

23 votes

5 answers

3k views

Is there a topological difference between an electric monopole and an magnetic monopole?

asked Mar 17, 2017 at 9:51

21 votes

2 answers

5k views

Interpretation of Dirac Spinor components in Chiral Representation?

asked Nov 18, 2014 at 10:38

20 votes

3 answers

2k views

What's the intuitive reason that phase space flow is incompressible in Classical Mechanics but compressible in Quantum Mechanics?

asked Jul 4, 2018 at 11:07

19 votes

2 answers

1k views

Why is a superposition of vacuum states possible in QCD, but not in electroweak theory?

asked Mar 28, 2017 at 6:35

19 votes

4 answers

2k views

What exactly do we mean by symmetry in physics?

asked Jan 21, 2015 at 8:25

18 votes

2 answers

4k views

What defines a large gauge transformation, really?

asked Feb 24, 2017 at 6:07

16 votes

3 answers

3k views

Is the Cosmological Constant locally zero?

asked Jun 6, 2017 at 8:03

16 votes

2 answers

3k views

Why do we need to renormalize in QFT, really?

asked Jun 14, 2017 at 6:48

16 votes

3 answers

2k views

Are there really left-chiral particles?

asked Nov 28, 2014 at 10:43

15 votes

2 answers

891 views

What's the role of the Dirac vacuum sea in quantum field theory?

asked Nov 21, 2019 at 16:15

13 votes

1 answer

3k views

Do gauge bosons really transform according to the adjoint representation of the gauge group?

asked Jun 30, 2015 at 11:24

13 votes

3 answers

634 views

Why intuitively, do we define symmetries as transformations that map solutions of the equations of motion into other solutions?

asked Feb 20, 2019 at 19:32

12 votes

1 answer

929 views

Why can consistent QFTs only arise from CFTs?

asked Jun 14, 2017 at 11:20

12 votes

3 answers

953 views

Why are topological properties described by surface terms?

asked Nov 20, 2017 at 10:30

12 votes

1 answer

4k views

Clarifications needed on Gauge Fixing and Ghosts [closed]

asked Oct 9, 2014 at 7:03

12 votes

3 answers

919 views

How does the interacting vacuum $|\Omega \rangle$ enter the theory?

asked Nov 22, 2019 at 10:00

11 votes

1 answer

4k views

Is General Relativity based on a Symmetry?

asked Oct 29, 2014 at 16:32

11 votes

1 answer

995 views

Why is only the third component of weak isospin used as a conserved quantity?

asked Nov 28, 2014 at 14:59

11 votes

5 answers

2k views

Is Parity really violated? (Even though neutrinos are massive)

asked Dec 9, 2014 at 9:59

11 votes

1 answer

378 views

How do fundamental symmetries vanish at the macroscopic level?

asked Jun 23, 2017 at 8:11

11 votes

0 answers

445 views

Is the QCD Lagrangian without a $\theta$-term invariant under large gauge transformations?

asked Feb 24, 2017 at 6:20

10 votes

1 answer

564 views

Heuristic Motivation for Lagrangian Formalism

asked Jun 3, 2014 at 7:24

10 votes

1 answer

3k views

Why do we use the complexification of the Lorentz group?

asked Jan 13, 2014 at 18:42

9 votes

4 answers

2k views

Do photons make the universe expand?

asked Mar 18, 2014 at 12:23

9 votes

3 answers

404 views

Are terms with spinors analogous to $ ( \partial_\mu \Phi )(\partial^\mu \Phi)$ forbidden in the Lagrangian?

asked Nov 12, 2014 at 15:20

9 votes

3 answers

2k views

Is there any Classical Mechanics system which needs to be described by a spinor?

asked Feb 9, 2019 at 9:04

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201 Questions

Why do we need complex representations in Grand Unified Theories?

Noether Theorem and Energy conservation in classical mechanics

Dirac spinors under Parity transformation or what do the Weyl spinors in a Dirac spinor really stand for?

Connection between conserved charge and the generator of a symmetry

Is there a topological difference between an electric monopole and an magnetic monopole?

Interpretation of Dirac Spinor components in Chiral Representation?

What's the intuitive reason that phase space flow is incompressible in Classical Mechanics but compressible in Quantum Mechanics?

Why is a superposition of vacuum states possible in QCD, but not in electroweak theory?

What exactly do we mean by symmetry in physics?

What defines a large gauge transformation, really?

Is the Cosmological Constant locally zero?

Why do we need to renormalize in QFT, really?

Are there really left-chiral particles?

What's the role of the Dirac vacuum sea in quantum field theory?

Do gauge bosons really transform according to the adjoint representation of the gauge group?

Why intuitively, do we define symmetries as transformations that map solutions of the equations of motion into other solutions?

Why can consistent QFTs only arise from CFTs?

Why are topological properties described by surface terms?

Clarifications needed on Gauge Fixing and Ghosts [closed]

How does the interacting vacuum $|\Omega \rangle$ enter the theory?

Is General Relativity based on a Symmetry?

Why is only the third component of weak isospin used as a conserved quantity?

Is Parity really violated? (Even though neutrinos are massive)

How do fundamental symmetries vanish at the macroscopic level?

Is the QCD Lagrangian without a $\theta$-term invariant under large gauge transformations?

Heuristic Motivation for Lagrangian Formalism

Why do we use the complexification of the Lorentz group?

Do photons make the universe expand?

Are terms with spinors analogous to $ ( \partial_\mu \Phi )(\partial^\mu \Phi)$ forbidden in the Lagrangian?

Is there any Classical Mechanics system which needs to be described by a spinor?