What causes the Hubble tension? · revision history
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Superseded · first revision · record
- Title
- What causes the Hubble tension?
- Plain
- Two careful ways of measuring how fast the universe expands today give different answers. The cause could be a measurement error or new physics.
- Precise
- Write $H0 = h x 3.24e-18\ \mathrm{s}^{-1}$. The SH0ES Cepheid plus type Ia supernova ladder gives $h = 0.730 \pm 0.010$, while Planck CMB in LCDM gives $h = 0.674 \pm 0.005$. Identify whether the discrepancy comes from distance-ladder systematics, from physics before recombination that shrinks the sound horizon, or from late-time physics, with a model that fits all data at least as well as LCDM.
- Settled by
- Independent one-percent $H0$ measurements that agree with one side, plus a model or systematic that removes the discrepancy without spoiling other fits.
- Kind
- phenomenon
- Answer type
- identification
- References
- (empty)
- Literature status
- contested
- Status note
- 2025 to 2026 JWST cross-checks by SH0ES find Cepheid, TRGB and JAGB distances agree within about 0.03 mag, while CCHP finds $h$ near 0.70.
- Posed since
- (empty)