Is the Standard Model a particle theory or a field theory?


by jnorman
Tags: field, model, particle, standard, theory
jnorman
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#1
Feb28-12, 11:11 AM
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just looking at the standard model, which describes a host of fundamental particles and bosons, one could assume that the SM is a particle model. however, most of what i read appears to indicate that particles are merely "excitations" or manifestations of a field, and it has been stated on this forum that SM is a field theory. this field explanation seems to make sense, since what we consider fundamental "particles" like quarks and leptons, are all point particles with zero volume - ie, there is "no-thing" there, only properties.

at the same time, science has no idea of how a field operates, and apparently is built on "spooky action at a distance", since no particles ever actually come into direct contact to impart changes in momentum or energy - they conduct these exchanges via "virtual" particle exchange (magic?).

what is your particular view of this? is SM a particle theory or a field theory? thanks.
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Demystifier
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Feb29-12, 03:47 AM
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I would say that SM is a quantum theory of particles described by the aid of quantum fields. In other words, the physical objects are particles, while the fields are a mathematical tool.

By the way, the "spooky action at a distance" in quantum theory has nothing to do with virtual particles.
MathematicalPhysicist
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Feb29-12, 04:18 AM
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Also the notion of "particle" is a mathematical notion, may it be a composite particle or a point-like particle.

martinbn
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Feb29-12, 07:04 AM
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Is the Standard Model a particle theory or a field theory?


I would say that it is a field theory.

Quote Quote by Demystifier View Post
I would say that SM is a quantum theory of particles described by the aid of quantum fields. In other words, the physical objects are particles, while the fields are a mathematical tool.
Why would you say that?
jnorman
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Feb29-12, 11:43 AM
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demyst - if virtual particles dont represent spooky action at a distance, i dont know what does. i know i am pulling a metaphor here, but the way particles interact, while very well modelled mathematically, is simply baffling from a "how does that happen?' perspective.
fzero
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Feb29-12, 12:26 PM
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Quote Quote by jnorman View Post
demyst - if virtual particles dont represent spooky action at a distance, i dont know what does. i know i am pulling a metaphor here, but the way particles interact, while very well modelled mathematically, is simply baffling from a "how does that happen?' perspective.
Virtual particle exchange is actually a great explanation of causality, since it explains why interactions cannot be transmitted faster than light. It's actually not at all like spooky action at a distance. It is inherently quantum mechanical though, since the effect of a virtual particle will not be known unless a measurement is made on the system.
jnorman
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#7
Feb29-12, 01:39 PM
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fz - how does one particle know that another particle is nearby and necessitates the exchange of virtual particles? how is the exchange of virtual particles initiated? what are virtual particles? maybe that is all clear to you, but i sure dont understand it.
Demystifier
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Mar1-12, 04:02 AM
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Quote Quote by jnorman View Post
demyst - if virtual particles dont represent spooky action at a distance, i dont know what does.
EPR correlations.
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Mar1-12, 04:05 AM
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Quote Quote by martinbn View Post
Why would you say that?
Because in SM the objects we MEASURE in practice are particles, not fields. Moreover, fermionic fields cannot be measured even in principle.
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Mar1-12, 06:45 AM
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Quote Quote by Demystifier View Post
Because in SM the objects we MEASURE in practice are particles, not fields. Moreover, fermionic fields cannot be measured even in principle.
That is irrelevant, the question is what the theory says, and QFT is a theory of fields.


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