String theory, while a highly speculative and complex area of physics, is also a subject of ongoing research and debate within the scientific community. It is important to note that calling aspects of string theory "absurd" might be subjective and dependent on personal viewpoints. However, I can highlight a few aspects that some people might find challenging or unconventional:
Extra Dimensions: String theory suggests that the universe contains more than the three spatial dimensions (length, width, and height) that we are familiar with. In fact, it proposes the existence of additional compactified dimensions (usually six or seven in total), which are curled up and not directly observable in our everyday experience. This idea might seem strange or unintuitive because we don't perceive these extra dimensions in our macroscopic world.
Multiverse and Landscape: String theory allows for the possibility of a vast number of different universes, collectively known as the multiverse. According to some versions of string theory, the properties of our universe, such as the values of fundamental constants, arise from the specific configuration of extra dimensions. This leads to a landscape of possible universes with different physical laws and properties. Critics argue that this notion lacks empirical testability and veers into a realm of unverifiable speculation.
Lack of Experimental Confirmation: As of now, string theory has not made any testable predictions that can be experimentally verified. Due to the extremely high energy scales at which string theory becomes relevant, it is challenging to design experiments that can directly probe its predictions. This absence of empirical evidence has led some to question its status as a scientific theory, as traditionally, scientific theories are supported by experimental observations.
Complexity and Mathematical Difficulty: String theory involves highly sophisticated mathematics, including advanced concepts from quantum field theory, general relativity, and geometry. The mathematics used in string theory can be intricate and challenging even for experts in the field. Some critics argue that the complexity of the theory makes it difficult to assess its validity or physical implications.
Lack of a Unique Formulation: String theory encompasses a range of different versions and approaches, such as Type I, Type IIA, Type IIB, heterotic strings, and M-theory, among others. These different formulations can sometimes seem disconnected and lack a unified framework. Critics argue that this lack of a unique formulation hampers the progress of the theory and makes it difficult to reach definitive conclusions.
It is worth mentioning that despite these potential challenges or criticisms, string theory remains an active area of research and a subject of fascination for many physicists. Researchers continue to explore its mathematical intricacies and potential implications for our understanding of fundamental physics and the nature of the universe.