The Digester

Preliminary DESI results suggest dark energy may be fading over time, a finding that would rule out a fixed cosmological constant and strengthen models such as cyclic cosmologies and string-theory scenarios with a changing extra dimension, while leaving room for non-string explanations and the need for more tests.

DESI measurements reported hints that the strength of dark energy may be decreasing over cosmic time, but the result is still preliminary.
If confirmed, dark energy would not be a fixed cosmological constant and lambda-CDM would need revision or replacement.
Cyclic universe models gain plausibility because they require decaying dark energy to stop expansion and trigger contraction and a bounce.
A string theory proposal by Cumrun Vafa and colleagues predicts weakening dark energy via a changing hidden extra dimension and has been shown to fit combined datasets as well as other evolving dark energy models.
Non-string alternatives also fit current data, and decisive tests will require sharper predictions and further observations, including probes of dark matter behavior and possible deviations from gravity at micrometre scales.

DESI hints of weakening dark energy revive cyclic and extra-dimension theories

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