Final answer:
The Friedmann equation describes the evolution of the cosmic scale factor, based on Einstein's general relativity and is key to our understanding of the universe's expansion.
Step-by-step explanation:
The Friedmann equation is a fundamental formula in physical cosmology that describes the evolution of the cosmic scale factor over time. Derived from Albert Einstein's theory of general relativity, the Friedmann equation shows how the scale factor evolves based on the curvature of space, the density of matter, and the pressure within the universe. Assuming a flat universe where curvature k is zero, the Friedmann equation simplifies, and it is the density p of the universe that primarily dictates the change in the scale factor a. This equation is crucial for understanding how the universe expands and provides a framework for the Big Bang cosmology.
The gravitational influence of mass, including dark matter and dark energy, plays a vital role in the geometry of space-time. This relationship is reflective of how mass and energy can lead to curvature and expansion in the universe. Additionally, the Hubble constant is a central concept in cosmology that is closely related to the Friedmann equation, as it helps measure the rate of expansion of the universe.