The Scientific Revolution began in the mid-1500s as scientists began questioning accepted beliefs and making new theories based on experimentation and observation, rather than relying solely on religious texts and ancient sources. This led to the development of the scientific method and major advances including Copernicus' heliocentric theory, Galileo's discoveries supporting it, Newton's laws of motion and universal law of gravitation, and discoveries in fields like chemistry, medicine, and microscopy that improved understanding of the natural world.