The theory of the Big Bang provides a comprehensive framework for understanding the early stages and subsequent evolution of the universe. However, there are still unresolved questions and phenomena that cannot be fully explained within the context of the Big Bang theory alone. Dark matter and dark energy are two such phenomena that play crucial roles in our current understanding of the universe, and their inclusion is necessary for a more complete explanation. Here's why:
Dark Matter: Observations of the motion of galaxies, galaxy clusters, and the large-scale structure of the universe indicate that there is more mass present than what is accounted for by visible matter (stars, gas, and dust). This discrepancy suggests the existence of a form of matter called dark matter, which does not interact with electromagnetic radiation and thus cannot be directly observed. Dark matter provides additional gravitational pull, enabling galaxies and galaxy clusters to form and maintain their observed structures. It also affects the distribution of matter in the early universe and the formation of cosmic structures. The precise nature of dark matter remains unknown, and its understanding is crucial to fully explain the dynamics and evolution of the universe.
Dark Energy: Observations of distant supernovae and the cosmic microwave background radiation have revealed that the expansion of the universe is accelerating rather than slowing down. This accelerated expansion is attributed to a repulsive force known as dark energy. Dark energy represents a large portion of the total energy density of the universe but has not been directly detected or explained by known fundamental forces. Its presence is required to explain the observed cosmic expansion and its accelerating rate. Understanding the nature of dark energy is essential to gain a complete understanding of the fundamental forces and energy content of the universe.
Including dark matter and dark energy in the framework of the Big Bang theory leads to the Lambda-CDM (Lambda-Cold Dark Matter) model, which provides a more comprehensive and consistent description of the universe's evolution and the observed large-scale structures. Ongoing research aims to shed light on the nature of dark matter and dark energy through various experiments, observations, and theoretical investigations to refine our understanding of the universe's history and composition.