The story you mentioned about Einstein figuring out the concept of time stopping at the speed of light at the age of 14 is a popular anecdote, but it is not entirely accurate. While Einstein did have early thought experiments and reflections on the nature of light and time, it is unlikely that he formulated the concept of time dilation and its relationship to the speed of light at such a young age.
The idea of time dilation and its connection to the speed of light emerged later in Einstein's life during his development of the special theory of relativity. It was through a series of scientific investigations, thought experiments, and mathematical formulations that he arrived at the theory's principles. These principles include time dilation, length contraction, and the constancy of the speed of light.
It is important to note that Einstein's work on the special theory of relativity was not solely based on personal thought experiments or individual insights. He built upon the foundation of previous scientific knowledge and engaged in extensive discussions and collaborations with other physicists of his time.
While the story of Einstein's youthful realization is often cited to highlight his genius and early curiosity, it is more of a simplified representation rather than an accurate account of how he developed the theory of relativity. Einstein's discoveries were the result of years of rigorous scientific investigation, theoretical work, and collaboration with other scientists.