What Is the Hubble's Law Cosmic Expansion Calculator?
Hubble’s Law describes the linear relationship between the distance to a galaxy and its recessional velocity as measured from Earth.
How Does the Hubble's Law Cosmic Expansion Calculator Work?
As photons travel across expanding spacetime, their wavelengths are stretched proportionally, producing cosmological redshift.
Hubble's Law Cosmic Expansion Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
v = H_0 \cdot d, \quad z \approx \frac{v}{c}, \quad t_{lookback} \approx \frac{d}{c}
Recession velocity v equals Hubble constant H0 times distance d. Redshift z is v over c.
How to Use the Hubble's Law Cosmic Expansion Calculator
- Enter the galaxy distance in Megaparsecs (Mpc).
- Optionally customize the Hubble parameter H₀ (default: 70 km/s/Mpc).
Step-by-Step Example Calculation
Coma Galaxy Cluster (100 Mpc)
Input Values:
distanceMpc:100
hubbleConstantH0:70
Worked Steps: At 100 Mpc distance (~326 million light years), galaxies recede at 7,000 km/s with redshift z = 0.0233.
Understanding Your Result
Recessional Velocity (km/s): Rate at which distance to the galaxy increases.
Redshift (z): Fractional increase in observed wavelength.
Lookback Time: Elapsed cosmic time since light departed the galaxy.
Factors That Affect the Result
- Value of Hubble constant H₀ and cosmological dark energy / matter density at high z.
When Should You Use This Calculator?
- Astronomy education, extragalactic spectroscopy, and cosmological distance ladder analysis.
Assumptions & Limitations
- Linear Hubble law is accurate for modest redshifts (z < 0.1). High redshifts require relativistic FLRW cosmology integration.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Linear velocity model with exact relativistic Doppler transformation.