The expansion of the universe, as described by the Hubble's law, refers to the expansion of space itself. This expansion is observed in the three spatial dimensions (length, width, and height), rather than in the time dimension.
According to the theory of general relativity, the fabric of spacetime can be influenced by the distribution of matter and energy. On large scales, such as the scale of the universe, the expansion of space itself can occur. This means that the distances between galaxies are increasing over time, leading to the observed phenomenon of the expanding universe.
The expansion of the universe is often visualized using the analogy of an expanding balloon. As the balloon inflates, the dots on its surface (representing galaxies) move away from each other. However, it's important to note that this analogy is limited and doesn't fully capture the complexities of the universe's expansion.
While the expansion of the universe is described in terms of space,is there implication on observed properties of light and thus the passage of time?