advanced_notions:quantum_field_theory:virtual_particles
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advanced_notions:quantum_field_theory:virtual_particles [2018/04/14 09:24] aresmarrero [Intuitive] |
advanced_notions:quantum_field_theory:virtual_particles [2019/02/01 10:11] jakobadmin [Abstract] |
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| * http://physics.stackexchange.com/questions/4349/are-w-z-bosons-virtual-or-not/22064#22064 | * http://physics.stackexchange.com/questions/4349/are-w-z-bosons-virtual-or-not/22064#22064 | ||
| * http://www.mat.univie.ac.at/~neum/physfaq/topics/vacfluc | * http://www.mat.univie.ac.at/~neum/physfaq/topics/vacfluc | ||
| + | * https://profmattstrassler.com/articles-and-posts/particle-physics-basics/quantum-fluctuations-and-their-energy/ | ||
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| <tabbox Concrete> | <tabbox Concrete> | ||
| Line 58: | Line 59: | ||
| </blockquote> | </blockquote> | ||
| - | <tabbox Abstract> | ||
| - | <note tip> | + | <blockquote>The calculational tool represented by Feynman diagrams suggests an often abused picture |
| - | The motto in this section is: //the higher the level of abstraction, the better//. | + | according to which “real particles interact by exchanging virtual particles”. Many |
| - | </note> | + | physicists, especially nonexperts, take this picture literally, as something that really and |
| + | objectively happens in nature. In fact, I have never seen a popular text on particle physics | ||
| + | in which this picture was not presented as something that really happens. Therefore, this | ||
| + | picture of quantum interactions as processes in which virtual particles exchange is one of | ||
| + | the most abused myths, not only in quantum physics, but in physics in general. Indeed, | ||
| + | there is a consensus among experts for foundations of QFT that such a picture should | ||
| + | not be taken literally. The fundamental principles of quantum theory do not even contain | ||
| + | a notion of a “virtual” state. The notion of a “virtual particle” originates only from a | ||
| + | specific mathematical method of calculation, called perturbative expansion. In fact, perturbative | ||
| + | expansion represented by Feynman diagrams can be introduced even in classical | ||
| + | physics [52, 53], but nobody attempts to verbalize these classical Feynman diagrams in terms of classical “virtual” processes. So why such a verbalization is tolerated in quantum | ||
| + | physics? The main reason is the fact that the standard interpretation of quantum | ||
| + | theory does not offer a clear “canonical” ontological picture of the actual processes in | ||
| + | nature, but only provides the probabilities for the final results of measurement outcomes. | ||
| + | In the absence of such a “canonical” picture, physicists take the liberty to introduce various | ||
| + | auxiliary intuitive pictures that sometimes help them think about otherwise abstract | ||
| + | quantum formalism. Such auxiliary pictures, by themselves, are not a sin. However, a | ||
| + | potential problem occurs when one forgets why such a picture has been introduced in the | ||
| + | first place and starts to think on it too literally. | ||
| + | <cite>Quantum mechanics: Myths and facts by H. Nikolic</cite> | ||
| + | </blockquote> | ||
| + | <tabbox Abstract> | ||
| + | <blockquote>"[I]n a closed system all quanta can be considered as virtual." | ||
| + | <cite>[[https://journals.aps.org/pr/abstract/10.1103/PhysRev.76.769|Richard Feynman]]</cite></blockquote> | ||
| <tabbox Why is it interesting?> | <tabbox Why is it interesting?> | ||
| <blockquote>There are no real one-particle systems in nature, not even few-particle | <blockquote>There are no real one-particle systems in nature, not even few-particle | ||
advanced_notions/quantum_field_theory/virtual_particles.txt · Last modified: 2019/02/01 11:58 by jakobadmin
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