1. What is Redshift?

Redshift (z) is a measure of how much the light from an object has been stretched to longer wavelengths due to the expansion of the universe. It's a key concept in cosmology for measuring distances to faraway galaxies.

2. How Does the Calculator Work?

The calculator uses the redshift equation:

Where:

• \( z \) — Redshift (dimensionless)
• \( c \) — Speed of light (3 × 10⁸ m/s)
• \( H_0 \) — Hubble constant (km/s/Mpc)
• \( 3.26 \times 10^6 \) — Conversion factor from parsecs to light years

Explanation: The equation converts redshift to a distance in light years using the Hubble constant and appropriate unit conversions.

3. Importance of Redshift Calculation

Details: Calculating distances from redshift is fundamental to cosmology, helping us map the large-scale structure of the universe and understand its expansion history.

4. Using the Calculator

Tips: Enter redshift (z) as a positive number (e.g., 0.05 for a modest redshift). The Hubble constant is typically between 67-74 km/s/Mpc (default is 70).

5. Frequently Asked Questions (FAQ)

Q1: What range of redshifts is this valid for?
A: This simple calculation works best for z < 0.1. For higher redshifts, relativistic effects become important.

Q2: Why does the Hubble constant matter?
A: Different measurements give slightly different H₀ values, which affects distance calculations. This is part of the "Hubble tension" in cosmology.

Q3: Is this the actual distance to the object?
A: This gives the "Hubble distance" which is an approximation. The true distance depends on the cosmological model.

Q4: What's the relationship between redshift and lookback time?
A: Higher redshift means we're seeing the object further back in time, but the exact relationship requires integration of the Friedmann equations.

Q5: Can this be used for very nearby objects?
A: For very small redshifts (z < 0.01), peculiar velocities may dominate over Hubble flow, making distance estimates less reliable.