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Cosmological Redshift Formula:
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Cosmological redshift is a measure of how much the light from an object in the universe has been stretched (redshifted) due to the expansion of the universe. It's a key concept in observational cosmology and helps determine distances to faraway galaxies.
The calculator uses the relativistic redshift formula:
Where:
Explanation: This formula accounts for relativistic effects when objects are moving at significant fractions of the speed of light.
Details: Redshift measurements are crucial for determining distances to astronomical objects, studying the expansion rate of the universe, and understanding the large-scale structure of the cosmos.
Tips: Enter the velocity of the object in meters per second. The speed of light is fixed at 3 × 10⁸ m/s. Velocity must be less than the speed of light.
Q1: What's the difference between cosmological and Doppler redshift?
A: Cosmological redshift is due to the expansion of space itself, while Doppler redshift is due to motion through space. This calculator uses the relativistic Doppler formula which is appropriate for high velocities.
Q2: What are typical redshift values?
A: Nearby galaxies might have z < 0.1, while distant quasars can have z > 7. The CMB has z ≈ 1100.
Q3: Can redshift be negative?
A: Yes, negative redshift (blueshift) occurs when objects are moving toward us, but cosmological redshift is always positive due to universal expansion.
Q4: What's the maximum possible redshift?
A: In theory, as v approaches c, z approaches infinity. In practice, the highest observed redshift is about z = 11.
Q5: How is redshift related to distance?
A: The relationship depends on cosmological parameters. For small z, distance ≈ z × c/H₀ (Hubble's law), but for large z the relationship becomes more complex.