The expansion of the universe and the principles of special relativity are not in conflict with each other. While special relativity describes the behavior of objects within spacetime, it does not account for the overall expansion of the universe on cosmological scales.
Special relativity is based on the concept of spacetime, where the geometry of space and time are interconnected. It explains how objects move and interact in a local region of spacetime. However, it does not provide a framework for describing the large-scale structure and dynamics of the entire universe.
The expansion of the universe is a concept that arises from general relativity, which is a more comprehensive theory of gravity developed by Albert Einstein. General relativity describes the curvature of spacetime caused by the distribution of matter and energy. It allows for the possibility of the universe to expand or contract on cosmological scales.
Observations, such as the redshift of distant galaxies, indicate that the universe is indeed expanding. Moreover, measurements of the expansion rate, known as the Hubble constant, suggest that the rate of expansion is increasing. This accelerated expansion is attributed to a mysterious form of energy called dark energy, which is thought to permeate the universe and drive its expansion.
It's important to note that special relativity remains a valid and essential framework for understanding the behavior of objects within spacetime. However, to comprehend the dynamics of the entire universe and its expansion, the more comprehensive theory of general relativity is required.