The idea that string theory might imply the existence of multiple universes with different laws of physics is related to the concept of a "multiverse." It's important to note that the multiverse hypothesis is speculative and not yet confirmed by empirical evidence. However, within the framework of string theory, there are certain proposals that suggest the possibility of a multiverse, such as the landscape of string theory vacua.
The landscape of string theory vacua refers to the vast number of possible configurations or solutions of string theory that can give rise to different universes with distinct laws of physics. These solutions arise from the different ways in which the extra dimensions of string theory can be compactified or curled up. The specific compactification scheme determines the properties of the resulting universe, such as the number of dimensions, particle content, forces, and fundamental constants.
In this scenario, the laws of physics and the characteristics of each universe are not fundamental or fixed but rather emerge from the specific configuration of the extra dimensions. The variations in the laws of physics arise from different choices of the compactification scheme, resulting in different patterns of matter, forces, and particles.
As for what led to the formation of these universes and the varying laws, it's an area of ongoing research and speculation. Some proposals involve cosmic inflation and quantum fluctuations during the early universe. According to these ideas, during a phase of rapid expansion in the early universe, quantum fluctuations could give rise to the formation of different regions with distinct properties, leading to the birth of separate universes within a multiverse.
However, it's important to highlight that the precise mechanism behind the emergence of the multiverse and the selection of specific laws of physics among its universes remains an open question. Understanding the origin and characteristics of the multiverse, if it indeed exists, is an active area of research in both string theory and cosmology.