Time has been understood in very different ways throughout the history of science. In classical physics, time was seen as absolute and universal. Isaac Newton imagined it as a constant, unchanging flow that ticks the same for everyone, everywhere in the universe. This view was simple, intuitive, and sufficient for understanding motion, gravity, and everyday phenomena.

Modern physics, however, has challenged this classical idea. Albert Einstein’s theory of relativity showed that time is relative—it can slow down or speed up depending on speed and gravity. Unlike the rigid clocks of Newton, time in Einstein’s universe is flexible, linked to space itself in a four-dimensional fabric called space-time. Furthermore, quantum physics hints that at the smallest scales, time may not even flow smoothly, but could behave in discrete steps or emerge from more fundamental processes.

The shift from classical to modern views of time reveals how our understanding evolves with science. What seemed fixed and universal is now seen as dynamic and context-dependent. Studying both perspectives helps us appreciate how the nature of time is both simple in everyday life and profoundly complex at the extremes of the universe.