The concept of the universe coming from "nothing" can be a bit counterintuitive, but I'll do my best to explain it in simple terms.
When scientists talk about the universe coming from "nothing," they are referring to the idea that the universe originated from a state devoid of matter, energy, space, and even time as we understand it. This "nothing" doesn't mean an absolute void, but rather a state where the laws of physics as we know them might not apply.
According to current scientific theories, such as the Big Bang theory, the universe began about 13.8 billion years ago. At that time, the entire universe was concentrated into an incredibly tiny and incredibly dense point called a singularity. This singularity contained all the matter, energy, and even space and time that would eventually make up our universe.
The precise conditions that led to the Big Bang are still not fully understood, and there are ongoing scientific investigations into this area. However, based on our current understanding, the universe underwent a rapid expansion known as inflation immediately following the Big Bang. During this expansion, space itself stretched and expanded, and matter and energy became more spread out.
So, when scientists say the universe came from "nothing," they mean that the entire universe emerged from this incredibly dense and tiny singularity, which itself might be considered a "nothing" because it lacked the familiar properties of our universe. The laws of physics, including space and time, as we know them today, began to take shape and unfold during the expansion that followed the Big Bang.
It's important to note that this explanation is based on our current scientific understanding, and our knowledge is always evolving as we continue to study and explore the mysteries of the universe.