The question you're asking is a topic of ongoing scientific inquiry and speculation. The concept of a complete void, devoid of any matter or energy, is often referred to as "nothingness" or "absolute nothingness." However, it is important to note that the notion of true nothingness is a challenging concept to define and understand.
According to our current understanding of physics, empty space is not truly empty but is filled with a background energy known as vacuum energy or zero-point energy. This energy arises due to the inherent uncertainty of quantum mechanics, even in the absence of matter or radiation. It is a fundamental part of the fabric of spacetime.
However, this vacuum energy does not spontaneously create observable energy in the way you described. While quantum fluctuations can temporarily create particle-antiparticle pairs, they quickly annihilate each other, resulting in no net gain of energy. The total energy of the universe, including matter and radiation, remains conserved over time.
As for the origin of the universe, our current scientific understanding reaches back to the Big Bang, which is considered the earliest known state of the universe. The exact nature of what preceded the Big Bang or how the universe came into existence is still an open question in cosmology. The origin of the universe is an area of active research and remains a subject of scientific investigation and theoretical speculation.
It is worth noting that when scientists refer to "nothing," they often mean an absence of particles and fields as we currently understand them. However, it does not necessarily imply an absence of fundamental physical laws or principles that govern the behavior of the universe.