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0answers
47 views

Actions at a distance vs. contact interaction

The ancestors could not imagine an action at a distance (in German: "Fernwirkung"). Today physicists don't take serious its opposite anymore (in German: "Kontaktwechselwirkung"). So my first question ...
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1answer
58 views

Definition: Coupling [closed]

What does it mean to say that 2 fields are coupled? More generally, what does "coupling" mean?
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3answers
839 views

Long/short-range interaction

A potential of the form $r^{-n}$ is often considered long-range, while one that decays exponentially is considered short-range. Is this characterization simply relative/conventional, or is there a ...