Expansion of the Universe

Edwin Hubble's 1929 observation that galaxies recede proportionally to their distance provided the first concrete proof of cosmic expansion, overturning the previously held static universe model. This discovery established the dynamic framework for all modern cosmology, demonstrating that the universe is not fixed but continuously growing. Hubble's law, a cornerstone of astrophysics, confirms a linear relationship for galactic recession out to over 10 billion light-years. Today, the measured Hubble constant is roughly 70 kilometers per second per megaparsec. This foundational understanding laid the groundwork for later discoveries, including the age and ultimate fate of the universe.