It's important to clarify that atheism, as a stance, doesn't necessarily offer a single explanation for the creation of the universe. Atheism is simply the absence of belief in gods or deities; it does not constitute a unified belief system or set of explanations for cosmological origins.
Atheists, like people of any other belief system, have diverse views on the origins of the universe. While some atheists might be proponents of certain scientific theories, others may simply acknowledge that we don't have a definitive answer and are comfortable with uncertainty.
Regarding the idea of something coming from nothing, the current understanding in cosmology is that the universe likely underwent a rapid expansion event known as the Big Bang, approximately 13.8 billion years ago. However, the concept of "something from nothing" is a complex topic, and it is essential to differentiate between philosophical and scientific perspectives.
From a scientific standpoint, theories such as quantum mechanics and inflationary cosmology suggest that the universe's initial singularity was not "nothing" in the philosophical sense but rather a state where the laws of physics, as we understand them, break down. Quantum fluctuations, for example, can create particles seemingly out of nothing in certain conditions, which adds complexity to our understanding of "nothingness."
Philosophically, the question of why there is something rather than nothing is a topic of ongoing philosophical debate. Some philosophers argue that the question itself may be flawed or ill-posed, as "nothing" may be a concept beyond human comprehension. Others propose various metaphysical ideas or hypotheses to grapple with the nature of existence.
It is important to note that scientific understanding evolves with ongoing research and observations, and what we know today may be refined or expanded upon in the future. the question of the universe's ultimate origin remains an open and active area of scientific and philosophical investigation.