قانون هابل والكون المتوسع

Hubble's Law and the Expanding Universe

• Hubble's Law states that the speed at which galaxies recede from Earth is directly proportional to the distance between Earth and the galaxies.
• Galaxies are moving away from Earth at high speeds in all directions.
• The farther the galaxy, the faster it moves away.
• The ratio of speed to distance is constant, a crucial factor in calculating the rate of expansion of the universe.
• This constant ratio is called Hubble's constant (Ho).

Hubble's Constant Calculation

• Hubble's constant (Ho) is calculated by the formula: Ho = v/d
• where:
• v is the speed of the galaxy's recession from Earth.
• d is the distance between Earth and the galaxy.
• This formula demonstrates the direct relationship between the distance and speed of receding galaxies.

The Expanding Universe and Hubble's Constant Implications

• Hubble's observation provided evidence for the expanding universe based on the Big Bang theory.
• All components of the universe are moving at constant speeds relative to one another as the universe expands.
• The rate of cosmic expansion is directly related to distance.
• The units of the expansion rate are kilometers per second.
• The unit of distance is million light-years (megaparsecs)

Doppler Effect and Hubble's Law

• Hubble used the Doppler effect (a change in observed wavelength caused by a moving source of waves, relative to an observer) to measure the expansion of the universe.