Higher Tier: Hubble's Law and the Age of the Universe
Part of Red Shift & Big Bang — GCSE Physics
This higher tier covers Higher Tier: Hubble's Law and the Age of the Universe within Red Shift & Big Bang for GCSE Physics. Revise Red Shift & Big Bang in Space Physics for GCSE Physics with 13 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 11 of 14 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 11 of 14
Practice
13 questions
Recall
12 flashcards
🎓 Higher Tier: Hubble's Law and the Age of the Universe
Hubble's Law states that the recession velocity of a galaxy is proportional to its distance:
v = H₀ × d
recession velocity (km/s) = Hubble constant × distance (megaparsecs)
The Hubble constant H₀ is approximately 70 km/s per megaparsec (though its exact value is debated). By taking the reciprocal of H₀ (after converting units), you can estimate the age of the universe. The current best estimate gives about 13.8 billion years.
This is only an estimate because the expansion rate has not been constant throughout the universe's history — the universe was decelerating due to gravity in its early life, but is now accelerating due to a mysterious "dark energy."