E6 Dark Energy

Topic

The central element of this model is dark energy, which accounts for more than two-thirds of the universe's energy content and is the direct cause of its accelerated expansion.

The simplest model treats this dark energy as a cosmological constant, with a fixed equation of state that does not change at all over time.

The discrepancy between the observed value of this dark energy and the value naively predicted by quantum physics is approximately one hundred and twenty orders of magnitude—the greatest unsolved problem in all of theoretical physics.

Quintessence models, by contrast, propose a dynamic field whose equation of state *can* vary over time; indeed, the latest data from major surveys already hint—albeit with modest statistical significance—that this equation of state might not be strictly constant. Thus, from the dark energy with which this document begins to the potential time-variation with which it concludes—taking in the cosmological constant and the "one hundred and twenty orders of magnitude" problem along the way—dark energy ensures that two-thirds of the entire universe hinges today on a single, as-yet-unanswered question: whether or not that energy is exactly constant.

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