The \"quantum realm\" is not really a \"space\" in the sense of a physical region or volume, like we usually understand the term. It refers to the scale at which quantum mechanical effects become apparent, which is extremely small -- much smaller than individual atoms. Quantum mechanics is a branch of physics that deals with phenomena on this very small scale, such as the behavior of electrons, photons, and other elementary particles.\n\nOn the other hand, the known universe is everything we can observe from Earth or from space-based telescopes and other instruments, extending for billions of light years in all directions. It contains a vast number of galaxies, each containing billions or trillions of stars, along with all the other matter and energy in the universe.\n\nSo in terms of physical size or volume, the known universe is incomparably larger than the scale of phenomena typically described by quantum mechanics.\n\nHowever, it's worth noting that quantum mechanics and the theory of relativity -- which describes the large-scale structure of the universe -- are both fundamental aspects of our current understanding of physics. Even though they operate on very different scales, they are both essential for a complete description of the universe. Efforts to reconcile these two theories into a single, unified theory of quantum gravity is one of the major ongoing challenges in theoretical physics.\n\nQuestion by: Bigboy
Question by:
Bigboy