New early dark energy

The authors discuss in detail a popular scenario to alleviate the current Hubble tension (different measurements of the expansion rate of the Universe show a 4. 4 discrepancy), namely ``early dark energy''. Hereby a false vacuum early on acts as an additional repulsive force (dark energy) but decays quickly enough to remain consistent with numerous other observational data. Contrary to the usual approach, a first order phase transition is considered, allowing in a minimal model a reduction of the tension to 2. 5.