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No-go theorem for k-essence dark energy
Camille Bonvin1, Chiara Caprini, Ruth Durrer
1Département de Physique Théorique, Université de Genève, 24 quai Ernest Ansermet, CH-1211 Genève 4, Switzerland. camille.bonvin@physics.unige.ch
Physical Review Letters
|October 10, 2006
Summary
K-essence theories, proposed to explain dark energy and the coincidence problem, require superluminal propagation for field fluctuations. This finding suggests that k-essence models violate causality, posing challenges for their theoretical consistency.
Area of Science:
- Cosmology
- Theoretical Physics
- Quantum Field Theory
Background:
- The coincidence problem in cosmology refers to why dark energy and matter densities are comparable today.
- K-essence theories are proposed as a potential explanation for dark energy, a mysterious component driving the accelerated expansion of the universe.
Purpose of the Study:
- To investigate the implications of k-essence theories for causality and consistency within the framework of fundamental physics.
- To determine if k-essence can simultaneously address the coincidence problem and function as dark energy without violating established physical principles.
Main Methods:
- Analysis of k-essence field equations and their implications for the propagation speed of fluctuations.
- Examination of causality conditions within the context of Lorentz invariance for k-essence models.
Main Results:
- K-essence models that solve the coincidence problem and act as dark energy necessitate superluminal propagation of field fluctuations at certain stages.
- Such superluminal propagation inherently violates causality, preventing a consistent, time-ordered succession of events in a Lorentz-invariant manner.
Conclusions:
- Successful k-essence models, as currently formulated, are incompatible with causality.
- K-essence cannot be derived as a low-energy effective field theory from a consistent, causal high-energy theory due to inherent causality violations.
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