Group 1 - The concept of parallel universes is not merely a creation of science fiction but is derived from scientific observations and theories [1] - There are various theories regarding parallel universes, some of which are simpler to understand while others are more complex, particularly those related to string theory [3][32] - The observable universe is limited to a sphere with a radius of approximately 41 billion light-years due to the finite speed of light and the expansion of the universe [5][12] Group 2 - The concept of the observable universe suggests that regions beyond our observable limits are completely independent and cannot be influenced by us [7][11] - The universe's expansion has been accelerating since about 7 billion years ago, which means that some galaxies currently within our observable universe may eventually move beyond our reach [12] - If the universe is infinite, there could be countless parallel universes with identical arrangements of particles, leading to the existence of duplicates of ourselves in different scenarios [14][16] Group 3 - The inflationary universe theory addresses the uniformity of cosmic microwave background radiation by proposing a rapid expansion of the universe shortly after the Big Bang [18][22] - This rapid inflation occurred approximately 10^-36 seconds after the Big Bang and expanded the universe by a factor of 10^26 [22] - The concept of eternal inflation suggests that while our local universe may have stopped inflating, the overall universe continues to expand indefinitely, creating numerous "pocket" universes [26][31] Group 4 - String theory introduces the idea of multiple dimensions and membranes, suggesting that our universe exists on a three-dimensional membrane among many others [32] - Quantum parallel universe theory posits that when a quantum event occurs, the universe splits into multiple branches, each representing different outcomes [57][61] - The double-slit experiment illustrates the wave-particle duality of electrons, leading to the conclusion that they can exist in multiple states simultaneously until observed [40][49]