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Cosmological concept · Cosmology

The Hubble Tension

Cosmology & UniverseScientific Debate

Definition

The unresolved disagreement between measurements of the Hubble constant from the early and the local Universe.

Scientific overview

Measurements of the expansion rate anchored in the early Universe (the CMB) give about 67 km/s/Mpc, while direct measurements in the nearby Universe give about 73 km/s/Mpc. The gap is now statistically significant and has resisted explanation as a simple error.

Open questions

  • Is the tension due to measurement systematics or new physics?
  • Does it require modifying ΛCDM (e.g. early dark energy)?

Measured by

Knowledge connections

Sources & references

The primary and reference sources this topic draws on.

  • NASANational Aeronautics and Space Administration

    Mission data, planetary science, space telescopes, and public-domain imagery.

    Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.

  • Planck CollaborationESA Planck mission / Planck Collaboration

    Cosmic microwave background maps and the cosmological parameters of the ΛCDM model.