No-go theorem
Template:Short description Template:Distinguish In theoretical physics, a no-go theorem is a theorem that states that a particular situation is not physically possible. This type of theorem imposes boundaries on certain mathematical or physical possibilities via a proof by contradiction.<ref name=Oldofredi2018>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Instances of no-go theoremsEdit
Full descriptions of the no-go theorems named below are given in other articles linked to their names. A few of them are broad, general categories under which several theorems fall. Other names are broad and general-sounding but only refer to a single theorem.
Classical electrodynamicsEdit
- Antidynamo theorems are a general category of theorems that restrict the type of magnetic fields that can be produced by dynamo action.
- 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.
Non-relativistic quantum mechanics and quantum informationEdit
- Bell's theorem<ref name=Oldofredi2018/>
- Kochen–Specker theorem<ref name=Oldofredi2018/>
- PBR theorem
- No-hiding theorem
- No-cloning theorem
- Quantum no-deleting theorem
- No-teleportation theorem
- No-broadcast theorem
- The no-communication theorem in quantum information theory gives conditions under which instantaneous transfer of information between two observers is impossible.
- No-programming theorem<ref name=Nielsen-Chuang-1997>Template:Cite journal</ref>
- Von Neumann's no hidden variables proof
Quantum field theory and string theoryEdit
- Weinberg–Witten theorem states that massless particles (either composite or elementary) with spin <math>\; J > \tfrac{1}{2} \;</math> cannot carry a Lorentz-covariant current, while massless particles with spin <math>\; J > 1 \;</math> cannot carry a Lorentz-covariant stress-energy. It is usually interpreted to mean that the graviton Template:Nowrap in a relativistic quantum field theory cannot be a composite particle.
- Nielsen–Ninomiya theorem limits when it is possible to formulate a chiral lattice theory for fermions.
- Haag's theorem states that the interaction picture does not exist in an interacting, relativistic, quantum field theory (QFT).<ref>Template:Cite journal</ref><ref name=Oldofredi2018/>
- Hegerfeldt's theorem implies that localizable free particles are incompatible with causality in relativistic quantum theory.<ref name=Oldofredi2018/>
- Coleman–Mandula theorem states that "space-time and internal symmetries cannot be combined in any but a trivial way".
- Haag–Łopuszański–Sohnius theorem is a generalisation of the Coleman–Mandula theorem.
- Goddard–Thorn theorem
- Maldacena–Nunez no-go theorem: any compactification of type IIB string theory on an internal compact space with no brane sources will necessarily have a trivial warp factor and trivial fluxes.<ref>Template:Cite book</ref>
- Reeh–Schlieder theorem<ref name=Oldofredi2018/>
General relativityEdit
- No-hair theorem, black holes are characterized only by mass, charge, and spin
Proof of impossibilityEdit
{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} In mathematics there is the concept of proof of impossibility referring to problems impossible to solve. The difference between this impossibility and that of the no-go theorems is that a proof of impossibility states a category of logical proposition that may never be true; a no-go theorem instead presents a sequence of events that may never occur.