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Name: Bob
Status: student
Grade: 9-12
Location: IL
Country: USA
Date: Spring 2013

How do we know that there are force carriers between particles?

Hi Bob,

I completely understand pressing the question as to the factual existence of force carriers. Evidence appears to mounting that points to several of these vector bosons that have been predicted, but hard evidence and study has been difficult to come by.

According to wave-particle theory, if there is a wave of an energy field, then there must be a particle associated with it. There are a number of these force carriers: Photons, W bosons, and Z bosons are excitations of the electroweak gauge fields; gluons are excitations of the strong gauge field, then there is the Higgs boson(s), an excitation of the Higgs field. Then there are fermions, mesons and a graviton.

Force carriers are a hypothetical mathematical means to help explain interactions between larger particles. The Hamiltonian (a mathematical) operator of the force is an integral product of a finite number of operators of particles. For the electromagnetic force between two electrons, those operators are of electrons and photons. That doesn't mean that any electron or photon is annihilated or created.

The photon being a carrier for the electromagnetic force only means that its operators appear in the Hamiltonian, not that they themselves actually appear in the interaction.

This study into the Standard Model is in transition, studies at CERN look promising to help our understanding of these interactions.

Thank you for your interesting question!

Peter E. Hughes, Ph.D., Milford, NH

Hi Bob,

Thanks for the question. For some of the elementary particles, the existence of force carriers (such as gluons) are postulated. The force carrier (of the electromagnetic force) between charged particles is the photon. There is much experimental evidence for the photon. This evidence has been accumulating since the 1910's.

I hope this helps. Please let me know if you have more questions. Thanks Jeff Grell

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