Scalar Field
Quintessence is a scalar field whose equation of state wq, defined as the ratio of its pressure pq and its density q, is given by the potential energy and a kinetic term:
- .
Hence, Quintessence is dynamic, and generally has a density and equation of state that varies with time. By contrast, a Cosmological Constant is static, with a fixed energy density and wq = −1.
Read more about this topic: Quintessence (physics)
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