The question of what precisely initiated the Big Bang is still a topic of scientific inquiry and debate. The Big Bang theory itself describes the expansion of the universe from a highly dense and hot state around 13.8 billion years ago. However, the specific cause or trigger of the Big Bang remains an active area of research.
Two hypotheses you mentioned have been proposed as possible explanations:
Quantum Fluctuations: According to some theoretical models, quantum fluctuations at a minuscule scale could have caused the rapid expansion of the universe. These fluctuations occur on extremely small length scales and can lead to the creation of particles and energy. It is suggested that such fluctuations might have initiated the cosmic expansion.
Colossal-sized Black Hole: Another speculative idea is that the Big Bang could have been triggered by the formation or collapse of a colossal-sized black hole in a previous universe. This hypothetical black hole could have compressed matter and energy to a point where it triggered a new universe's expansion.
It is important to note that both of these hypotheses are speculative and remain areas of active research. Scientists continue to investigate the origins of the universe using theoretical models, mathematical frameworks, and data from cosmological observations. However, at present, we do not have definitive evidence or a complete understanding of what precisely caused the Big Bang.