Dark matter is believed to interact with itself gravitationally, meaning that it can be influenced by the gravitational pull of other dark matter particles. This interaction is crucial for the formation of large-scale structures in the universe, such as galaxies and galaxy clusters.
The concept of a shadow universe made entirely of dark matter is an intriguing idea. It suggests the possibility that there could be a parallel universe or a separate sector of the universe primarily composed of dark matter, with its own dark matter structures and dynamics. This hypothetical shadow universe could exist alongside our observable universe, interacting with it only through gravitational effects.
However, it's important to note that the existence of a shadow universe made entirely of dark matter is purely speculative at this point. While dark matter is thought to interact gravitationally with itself, our current understanding of dark matter and its properties is limited. We have not yet observed or directly detected any other interactions or manifestations of dark matter beyond its gravitational effects.
Exploring the nature and properties of dark matter is an active area of research, and ongoing experiments and observations aim to shed light on its composition and behavior. Discovering any potential connections or interactions with a shadow universe or parallel sector of the universe would require significant advancements in our understanding of dark matter and the development of new observational techniques or experiments that can probe such phenomena.