No-go theorem

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Not to be confused with No-ghost theorem.

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.[1][2]

Examples[edit]

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.

In quantum information theory, a no-communication theorem is a result which gives conditions under which instantaneous transfer of information between two observers is impossible.

Other examples:

See also[edit]

References[edit]

  1. ^ Bub, Jeffrey (1999). Interpreting the Quantum World (revised paperback ed.). Cambridge University Press. ISBN 978-0-521-65386-2. 
  2. ^ Holevo, Alexander (2011). Probabilistic and Statistical Aspects of Quantum Theory (2nd English ed.). Pisa: Edizioni della Normale. ISBN 978-8876423758.