Hubble's law states that the velocity at which a galaxy moves away from us is directly proportional to its distance from us. This relationship supports the concept of an expanding universe.
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Hubble's law was formulated by Edwin Hubble in 1929.
The law is often expressed with the equation v = H₀d, where v is the galaxy's recessional velocity, H₀ is the Hubble constant, and d is the distance to the galaxy.
Hubble's discovery provided strong evidence for the Big Bang theory.
The value of the Hubble constant (H₀) helps determine the rate of expansion of the universe.
Observations of redshift in light from distant galaxies were key to establishing Hubble’s law.
Review Questions
What does Hubble's law imply about the movement of galaxies?
How does Hubble’s law support the concept of an expanding universe?
What role does redshift play in confirming Hubble’s law?
The leading explanation for how the universe began, proposing it started from a singularity approximately 13.8 billion years ago and has been expanding ever since.
Hubble Constant (H₀): A measure of the rate at which the universe is expanding, expressed in kilometers per second per megaparsec (km/s/Mpc).