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In theoretical physics, a no-go theorem is a theorem that states that a particular situation is not physically possible. Specifically, the term describes results in quantum mechanics like Bell's theorem and the Kochen–Specker theorem that constrain the permissible types of hidden variable theories which try to explain the apparent randomness of quantum mechanics as a deterministic model featuring hidden states.
The Weinberg–Witten theorem states that massless particles (either composite or elementary) with spin j > 1/2 cannot carry a Lorentz-covariant current, while massless particles with spin j > 1 cannot carry a Lorentz-covariant stress-energy. The theorem is usually interpreted to mean that the graviton (j = 2) cannot be a composite particle in a relativistic quantum field theory.
- Coleman–Mandula theorem
- Haag–Lopuszanski–Sohnius theorem
- Antidynamo theorems (e.g. Cowling's theorem)
- No-teleportation theorem
- No-cloning theorem
- No-broadcast theorem
- Quantum no-deleting theorem
- Earnshaw's theorem states that a collection of point charges cannot be maintained in a stable stationary equilibrium configuration solely by the electrostatic interaction of the charges.
- Gleason's theorem
- Haag's theorem
- Hohenberg–Kohn theorems
- Nielsen–Ninomiya theorem
- Proof of impossibility, the corresponding mathematical notion. A quote therefrom: "To prove that something is impossible is usually much harder than the opposite task; it is necessary to develop a theory."
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