Teori medan kuantum: Perbezaan antara semakan
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==Asal-usul==
Teori medan kuantum berasal daripada masalah untuk mengira tenaga yang disinarkan oleh sebiji [[atom]] ketika atom itu jatuh daripada satu [[keadaan kuantum]] kepada satu keadaan yang mempunyai paras tenaga yang lebih rendah. Pada tahun [[1925]], [[Max Born]] dan [[Pascual Jordan]] mengkaji masalah ini, dan bersama-sama dengan [[Werner Heisenberg]] pada tahun [[1926]], mereka membentuk teori kuantum untuk [[medan elektromagnet]] yang tidak mengambil kira [[pengutuban]] dan [[sumber (kalkulus vektor)|sumber-sumber]]. Teori mereka kini digelarkan [[teori medan bebas]].
Quantum field theory originated in the problem of computing the energy radiated by an [[atom]] when it dropped from one [[quantum state]] to another of lower energy. This problem was first examined by [[Max Born]] and [[Pascual Jordan]] in [[1925]]. In [[1926]], [[Max Born]], [[Werner Heisenberg]] and [[Pascual Jordan]] wrote down the quantum theory of the [[electromagnetic field]] neglecting [[polarization]] and [[source (vector calculus)|sources]] to obtain what would today be called a [[free field theory]]. In order to quantize this theory, they used the [[canonical quantization]] procedure. In [[1927]], [[Paul Dirac]] gave the first consistent treatment of this problem. Quantum field theory followed unavoidably from a quantum treatment of the only known classical field, ie, [[electromagnetism|the electromagnetic field]]. The theory was required by the need to treat a situation where the ''number of particles changes''. Here, one atom in the initial state becomes an atom and a [[photon]] in the final state.▼
Untuk mempergunakan teori kuantum pada
kaedah [[kuantisasi berkanun]]
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It was obvious from the beginning that the quantum treatment of the electromagnetic field required a proper treatment of relativity. Jordan and [[Wolfgang Pauli]] showed in [[1928]] that [[commutator]]s of the field were actually [[Lorentz invariant]]. By [[1933]], [[Niels Bohr]] and [[Leon Rosenfeld]] had related these commutation relations to a limitation on the ability to measure fields at [[space-like]] separation. The development of the [[Dirac equation]] and the [[hole theory]] drove quantum field theory to explain these using the ideas of [[causality (physics)|causality]] in relativity, work that was completed by [[Wendell Furry]] and [[Robert Oppenheimer]] using methods developed for this purpose by [[Vladimir Fock]]. This need to ''put together relativity and quantum mechanics'' was a second motivation which drove the development of quantum field theory. This thread was crucial to the eventual development of [[particle physics]] and the modern (partially) unified theory of forces called the [[standard model]].
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