The concept of time dilation was discovered and developed as part of Albert Einstein's theory of special relativity, which he introduced in 1905. Einstein's insights and the formulation of special relativity were based on a combination of theoretical reasoning, logical deduction, and experimental evidence.
Einstein's work was influenced by various earlier scientific developments and thought experiments. One of the notable influences was the Michelson-Morley experiment conducted in 1887, which aimed to detect the existence of an "ether," a hypothetical medium through which light was believed to propagate. The experiment yielded null results, suggesting that the speed of light is constant in all directions, regardless of the motion of the observer or the source of light.
Einstein's key postulate in developing special relativity was that the laws of physics, including the speed of light, are the same for all observers in uniform motion. This meant that the constancy of the speed of light was a fundamental principle that had to be reconciled with the existing understanding of space and time.
Einstein then employed a combination of thought experiments, mathematical reasoning, and logical deductions to derive the consequences of this postulate. Through these thought experiments, such as the famous "twin paradox," he deduced that time must appear to pass differently for observers in relative motion, leading to the concept of time dilation.
Experimental evidence confirming the existence of time dilation came later. One of the early experimental verifications was the measurement of the decay rates of subatomic particles known as muons. Muons are created in the upper atmosphere by cosmic ray collisions and are short-lived particles. However, due to their high velocity, time dilation causes them to survive longer during their journey to the Earth's surface than would be expected based on their normal decay rate. This phenomenon was confirmed through experiments and provided empirical evidence for time dilation.
Since then, numerous experiments have been conducted to validate the predictions of time dilation and special relativity, and the results have consistently supported the theory.
Overall, time dilation was discovered through a combination of theoretical reasoning, logical deduction, and experimental verification, with Albert Einstein's formulation of special relativity playing a pivotal role in shaping our understanding of this phenomenon.