1. What is the Hubble Constant?

The Hubble Constant (H₀) is a fundamental parameter in cosmology that measures the rate of expansion of the universe. It relates the recession velocity of galaxies to their distance from us.

2. How Does the Calculator Work?

The calculator uses the Hubble's Law equation:

Where:

• \( v \) — Recession velocity of the galaxy (km/s)
• \( d \) — Distance to the galaxy (Mpc)
• \( H_0 \) — Hubble constant (km/s/Mpc)

Explanation: The equation demonstrates the linear relationship between the recessional velocity of galaxies and their distance from Earth.

3. Importance of Hubble Constant Calculation

Details: Accurate measurement of the Hubble constant is crucial for determining the age of the universe, understanding cosmic expansion, and testing cosmological models.

4. Using the Calculator

Tips: Enter recession velocity in km/s and distance in megaparsecs (Mpc). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the current accepted value of the Hubble constant?
A: The value is approximately 70 km/s/Mpc, though measurements range from 67-74 km/s/Mpc depending on the method used.

Q2: Why is there a Hubble tension?
A: Different measurement methods (Cepheid variables vs. cosmic microwave background) yield slightly different values, creating ongoing debate in cosmology.

Q3: How is recession velocity measured?
A: Through redshift measurements of spectral lines using the Doppler effect.

Q4: What are the units of the Hubble constant?
A: The standard units are kilometers per second per megaparsec (km/s/Mpc).

Q5: Can this calculator be used for educational purposes?
A: Yes, this calculator is designed for educational use to demonstrate the relationship between recessional velocity and distance in cosmology.