Cosmologists and physicists strive to find a grand unified theory that unites the quantum world with gravity for several reasons, even though the ultimate reality might not conform to our notions of theoretical beauty. Here are some key motivations:
Understanding the Fundamental Nature of the Universe: Humans have an innate curiosity to understand the fundamental laws that govern the universe. Uniting the quantum world with gravity is seen as a significant step towards unraveling the deepest mysteries of nature and gaining a comprehensive understanding of how the universe works at its most fundamental level.
Consistency and Internal Coherence: The pursuit of a grand unified theory is driven by the desire for theoretical consistency and coherence. The currently accepted theories, such as the Standard Model of particle physics (which describes the quantum world) and General Relativity (which describes gravity), are both highly successful within their respective domains. However, they have different theoretical frameworks and are incompatible with each other. Scientists seek a unified theory that resolves this incompatibility and provides a more elegant and internally consistent description of the fundamental forces.
Bridging Knowledge Gaps: A grand unified theory has the potential to bridge knowledge gaps and address unanswered questions. It could provide insights into phenomena that are currently not well understood, such as the nature of dark matter, dark energy, the origin of the universe, or the behavior of matter in extreme conditions like black holes. A unified theory might offer a more comprehensive framework within which these phenomena can be explained.
Predictive Power: Grand unified theories often have predictive power. By unifying fundamental forces, these theories can make testable predictions about phenomena that lie beyond the reach of current experiments. Experimental verification or falsification of these predictions would not only provide empirical support for the theory but also guide future scientific investigations.
While nature itself may or may not adhere to our aesthetic notions of theoretical beauty, the pursuit of grand unified theories is driven by the desire for intellectual completeness, elegance, and coherence. Even if a grand unified theory is never fully realized or nature turns out to be different from our expectations, the pursuit itself often leads to new insights, breakthroughs, and advancements in our understanding of the universe.