What is the Time? | Definition, Scientific Explanation, facts and Examples

 

Everyone is aware of time, but its explanation and understanding are difficult. Science, philosophy, religion, and art explain it separately but its measurement system is the same in all. Clocks are based on seconds, minutes, and hours, while the bases of these units have changed throughout history. Their footprints date back to the ancient Sumerian civilization. The current universal unit of time is the second, which is measured by changes in the energy states of the cesium atom. But What is the time?

Scientific explanation

Physicists define time as follows: It is a sequence of events that happened in the past, from the present to the future. If a system does not change, then it is timeless or eternal. Time can be considered as the fourth dimension of reality that describes the events occurring in the three-dimensional space. It is not something we can see, touch, or feel but we can measure its passage.

The Arrow of Time

The equations of physics work equally Whether time is moving forward in the future (positive time) or going back in the past (negative time), there is a direction of time in the physical world, which is called the arrow of time.

Why time is irreversible is one of the most unsolved questions in science. One explanation is that the physical world follows the laws of thermodynamics.

The second law of thermodynamics states that the entropy of the system remains constant or increases within a closed system. If the universe is considered a closed system, then its entropy can never decrease. In other words, the universe cannot return to the state it was in before or at the first point. Time does not move backward.

Time Dilation

In classical mechanics, time is the same everywhere. Clocks that are calibrated to each other will always measure the same time. However, from the special and general theory of relativity given by Einstein, we know that Time is relative. It depends on the frame of reference of an observer. This can result in time dilation in which the time between two events traveling at speeds close to the speed of light will increase, meaning time dilation.

          As a moving clock moves more slowly than a stationary clock, its effects become more apparent as the moving clock approaches the speed of light. Clocks in a jet plane or clocks in orbit move more slowly than on Earth. Particles called muon are destroyed more slowly when they fall. The Michaelson Morley experiment confirmed length contraction and time dilation.

Time Travel

Time travel means that we move between different points in space in the same way that we move forward or backward at different points in time. Naturally, one can go forward in time. Astronauts in the International Space Station (ISS) move forward in time when they return to Earth because Earth moves more slowly than the station. However, traveling backward in time creates different problems. A problem is causality or cause and effect. Moving backward in time can cause a temporal paradox.

          The grandfather paradox is a classic example. According to this paradox, if you travel back in time and kill your grandfather before your mother or father were born, then you can prevent your birth. Many physicists believe that time travel in the past is impossible, but there are solutions to the time paradox Such as traveling between universes

Time Perception

The human brain has the ability to measure the passage of time. The magical center of the brain is the area responsible for daily or routine actions. But the chemicals flowing through the nervous system (neurotransmitters) and drugs have an effect over time. Chemicals that stimulate nerve cells so that they work faster than the normal clock speed while slowing down the nerve cells can reduce the ability to stimulate time. When time seems to speed up, the brain perceives the difference in more events in a given interval. In this situation, when a person is having fun, he feels that time passes fast. In some dangerous situations, it seems to slow down from time to time.

          Scientists believe that the brain does not become faster, but the amygdala becomes more active. The amygdala is the part of the brain that creates memories. As more memories are formed, time lengthens. The same relationship explains why older people feel time passes more quickly than when they were younger. Psychologists believe that the brain makes more memories from new experiences than from old experiences. As fewer new memories are formed later in life, time seems to pass faster.

The Beginning and End of Time

As far as the universe is concerned, time had a beginning. The starting point is 13.799 billion years ago when the Big Bang happened. We can measure the microwaves emitted by the Big Bang as cosmic background radiation. But before this, there was no radiation of any kind. One argument for the beginning of time is that if it stretched infinitely backward, then the night sky would be filled with the light of old stars.

Will the end of time?

          There is no answer to this question. If the universe expands forever, time will continue. If a new big bang occurs, our timeline will end and a new timeline will begin. In particle physics experiments, random particles are created from a vacuum Therefore, it does not seem that the universe is timeless or timeless, only time will tell.

 

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