Parallel Space, or Multiverse, can be viewed as individual “spaces” which are located throughout the universe in an infinite number. We usually recognize spaces as a “space” of infinite volume, a room with no walls. This may or may not be true in this theory. Currently, many scientists state that our universe is currently expanding, backing up their claim with the concept known as the "red shift". However, if our universe is expanding, there should be a barrier for it to expand. We usually give an analogy of an expanding balloon to introduce the concept of the increasing universe. We we put two dots on a balloon and blow into it, the distance between the two dots increase as you blow more and more into the balloon. This analogy, however, also may give a misconception that there is an end, a barrier to the universe. This may depend on how you define “our space”. One definition of our universe, a way to define the region of our space, is by light years. Light is extremely fast, with a speed of 299,792,458 meters per second. Despite this great speed, it still takes time for light to move a certain distance. Thus, with this quality, we can define the end of our universe. Think of our Earth as a center point, the (0,0,0) point of a 3-dimensional plane. From there, every light from every star, any luminaries will start their journey to reach Earth. When a “stream” of light reaches Earth, it will be able to be seen by us humans, either by eye or a telescope. At this instant, the second when that stream of light from a luminary reaches Earth, the distance of that star from Earth made into a radius of a sphere with Earth in the centre will be the boundary of our Universe. Then, when another stream of light further from the previous luminary reaches Earth, the distance from that star to Earth will be the new radius of the Sphere. This phenomenon is continuous; even now, streams of light from new luminaries will be reaching Earth. Thus, this can be explained as that our universe is actually increasing. The other way of defining our universe is just by our thoughts, or in other words, our imagination. We can just say that every single inch of the universe is subject to our space and that there is no barrier to it. Whatever the definition of the extent of our universe is, the parallel space theory can be applied to the universe with no barrier. Going back to the first definition of the universe, even though our universe may be growing every second close to the speed of light, the change will be minimal when observed from a far distance. In this circumstances, the multiple spaces can be viewed as individual balls. These individual balls are connected by wormholes. Another concept can be incorporated into this: mother spaces and daughter spaces. Although I do not know why they named it daughter-universe instead of son-universe, mother universes are basically the original spaces that existed, and the daughter-universe are the ones that were separated from the mother-universes. Thus, the daughter universe can be the mother universe of other daughter universes, and so on. These two kinds of universe(s) are connected to each other by wormholes.
