The term relativism belongs to philosophical views and is of many forms like Alethic relativism is the doctrine that tells us the truth is always relative to some particular frame of reference. Overall, relativity is all about the change in perception of different people at a different time in different frames of reference. A frame of reference is not a complicated concept. It is just something you decide is a fixed point or group of connected points. It is completely up to you. For example, when you look up at celestial objects in the sky, you fix the Earth as your frame of reference, and the Sun, Moon, etc seem to move across the sky. Everything is relative to something. People often drive their car real fast on highways, but it is not only the car that is moving. Earth itself is spinning on its axis at more than a thousand miles per hour. The universe itself is expanding. The universe is not only expanding but also the expansion rate is accelerating. Nothing is in absolute rest or absolute motion. Relativity is not just a science or Einstein or Newton or some kind of frustrating equation. Forget science. It’s midnight. You take your clock or darkness as the frame of reference.
You are reading this in the year 2020, probably the cursed year of the 21st century. Somebody will be reading this in 2021 or 2031 or whatsoever else. The time was even there when humans had no idea about numbers. You are eighteen years old that just meant the Earth has revolved around the Sun 18 times or so since the time you were born. The question that arises here is how to define time. Are the laws of physics constant in time? Does time exist? Does classical physics apply to the object moving at more than a thousand miles per second? Would length vary with speed? Is space homogeneous or isotropic? Your clocks run on batteries which make time slow for you as your batteries approach expiry date but not for me and somebody else with a brand new clock. You can reckon time independent of your psychological state.