Part 4/9:
To understand the complications surrounding string theory, we must delve into its origins, tracing back to Theodor Kaluza's groundbreaking discovery in 1919. By exploring general relativity in five dimensions, Kaluza found a remarkable correlation between gravity and electromagnetism. This concept evolved further when Oskar Klein compactified the extra dimension, positing that it could be shrunk to scales invisible to larger particles, leading to a new theory known as Kaluza-Klein theory.
However, Kaluza-Klein theory faced its challenges. Predictions of unseen elementary particles and fields indicated flaws. Despite these missteps, they laid the groundwork for string theory, which integrated more dimensions and complex geometries to address the deficiencies.