The concept you're referring to is often associated with the Big Bang theory, which is the prevailing cosmological model describing the origin and evolution of the universe. According to the Big Bang theory, the universe began as an extremely hot and dense state, often referred to as a singularity, which expanded and cooled over time.
However, it's important to note that the idea of all matter being condensed into a single point smaller than the tip of a pin is an oversimplified and misleading depiction. The singularity is a mathematical concept that represents a state of infinite density and temperature. It is not well understood and is thought to be beyond the realm of our current understanding of physics. The Big Bang theory describes the universe's subsequent expansion and evolution from that initial state.
The support for the Big Bang theory comes from a variety of observational and theoretical evidence, including:
Cosmic Microwave Background (CMB): The discovery of the CMB in 1965 provided strong evidence for the Big Bang. The CMB is a faint radiation that permeates the entire universe and is considered the remnant heat from the early stages of the universe. Its uniformity and the specific pattern of temperature fluctuations observed in the CMB match the predictions made by the Big Bang theory.
Redshift and Hubble's Law: The observation of redshift in the light from distant galaxies indicates that the universe is expanding. The redshift of light from distant objects is consistent with the idea that the universe has been expanding since its early stages. This observation supports the notion of an initial, hot, and dense state.
Abundance of Light Elements: The Big Bang theory successfully predicts the abundance of light elements in the universe, such as hydrogen and helium. The observed ratios of these elements match the predictions made by the theory.
Large-Scale Structure: Observations of the distribution of galaxies and the formation of large-scale structures, such as galaxy clusters and cosmic filaments, are consistent with the predictions of the Big Bang theory.
Nucleosynthesis: The Big Bang theory accurately predicts the production of heavier elements through a process called nucleosynthesis. It explains the origin of elements like lithium, deuterium, and beryllium in the early universe.
It's important to note that while the Big Bang theory provides a robust framework for understanding the evolution of the universe, the specifics of the initial singularity are still an active area of research. The singularity itself is thought to be inaccessible to direct observation or experimental confirmation due to the extreme conditions involved.