From an everyday perspective, time is easy to understand; however, defining or describing it becomes tricky. It becomes a paradox, considering that it is the most used concept in life. But the good news is that we can explain the concept of time. The most often asked questions related to time are: does time exist? What do we understand with time? Is it one-directional? Is it homogeneous? Humans created time as a physical quantity. Time is crucial both for science and for everyday life. But time does not stand as an essential category for the existence of the universe. In other words, only matter exists which has several fundamental properties.
One of its primary properties is its motion or its development (rate change) for which we use the word event. Time only quantifies the development aspect of the matter. Similarly to the inertia, which is another fundamental property of matter and the mass is its quantitative measure, so is the purpose of time for quantifying the development (rate of change) of matter. Time is our reflection on the development scale of a material system.
Why it flows only in one direction and is time homogeneous?
The development of matter is absolute, whereas time tells us how far it got. The way we measure the time allows us to find the answer on the last two questions: why it flows only in one direction and whether the time is homogeneous? As we use comparison to measure other physical quantities, so do we when we measure time. But what do we compare to measure time? Because time reflects the development (rate of change) of matter, it tells when and how long a particular event lasts; then we compare events with each other. More precisely, we compare the event which we want to determine its time-length relatively to a periodical event as a reference. The most usual activities as reference events are the apparent rotation of the Sun around the Earth or the rotation of the clock’s hands.
Time does not go back because the development is progressive.
Time does not go back because the development is progressive. In other words, even if the clock’s hand would move one step forward and one backward, there would still be two events. The minus sign is only a conventional operator. To have a representative measure of time, we need to have an event which its development is ideally periodic, i.e., its periods are preferable of the same length. This fact, plus the fact that the motion of a system with constant rectilinear motion has no effects on the events within the system makes time-homogeneous. In other words, in all the systems time passes the same. In the end, there is a famous quote saying: time is money! Right, because you earn money through work and development. So, yes, time is money because it measures your work, i. e. your development or your activity.
