From the March 2008 issue

Does the Hubble constant change over time?

David E. West, Kenmore, Washington
By | Published: March 1, 2008 | Last updated on May 18, 2023

Gemini Sparkle

Key Takeaways:

  • The term "Hubble constant" is debated, with some advocating for "parameter" due to its variability.
  • Measurements of the Hubble constant are continually refined, yielding greater precision.
  • Observations extend to increasingly earlier epochs in the universe's history.
  • The appellation "constant" becomes less suitable as measurements encompass more distant galaxies.
It does — which is why some prefer to call it a parameter. Measurements of the Hubble constant — the rate of the universe’s large-scale expansion — continue to improve and push to earlier and earlier times. As we look toward more and more distant galaxies, the name “constant” becomes increasingly inaccurate.