"People like us who believe in physics know that the distinction between past, present, and future is only a stubbornly persistent illusion." - Albert Einstein
There are a lot of things in this world that human beings can not comprehend. Time is one such thing. Humans began measuring time through the pattern of changes of day and night. Later, the ancient Egyptians invented the sundial.The time that they measured, back then, is different from the time that we measure now. Time plays an important role in various fields but defining it in such a way that it is common for all these fields is impossible. If time is a properly defined physical quantity then why can’t it be used commonly in all the fields? Time is used to define various quantities like velocity but it itself cannot be defined properly. Is Time really a physical quantity or is it something that our incapable mind make up to understand something that is beyond our reach?
You might have experienced time move very slowly when you are attending a lecture of the subject that you hate the most. But the same time moves at the speed of light when you are hanging out with your friends. Why do we feel this way? Even though you spend the same 45 minutes attending the lecture and hanging out with friends, the time that you spend with your friends moves much faster. Does this mean that time is not just a physical quantity but also has something to do with the emotions of a human being?
One of the main reasons we feel that way is that when we are thinking about time itself, it appears to move slowly. We constantly check the clock during lectures and ask our friends what time it is but when we hang out with friends we completely forget about it. So, it appears to move faster. This is called the Temporal Illusion which is nothing but the distortion of our sense of time.
This can further be explained with the help of the Holiday Paradox. A three hour delay when you travel to some place might feel like an eternity but once you arrive at the destination and enjoy the day, time flies by. This is called Prospective Timing. However, after a few days when you recollect the incidents, the three hour delay feels like a very short period of time and the day that you enjoyed feels much bigger. This is called Retrospective timing.
Time is like a river that flows from one event to another in a single direction which is towards the future. But this may not be true as various theories suggest that time does not flow at all, it just exists. Our reality can be divided into two types. In the first type, reality is a three dimensional place where every event occurs over time. In the second type, reality is a four dimensional place where nothing happens. The change in the four dimensional reality is just an illusion. Here, Past, Present and Future exist at the same time.
According to Einstein’s Theory of Relativity, time is combined along with the three dimensions forming a four dimensional Space-Time Continuum. He also states that everything that comes after the beginning of the Universe is defined already and nothing comes as a surprise. The Past, Present and the future exist together.
Theory of Relativity also deals with the concept of Time Dilation. It explains that your perception of time is dependent on how fast you are moving and how close you are to an object. The best way to explain this is with the help of the movie, Interstellar. When the astronauts leave earth, time starts flowing differently for them when compared to those who were on earth.
Again, when Cooper and Brand travel to the unknown planet near the black hole to search for Dr.Mann, time moves slowly for those who were on the planet because it was closer to a Black hole. The concept behind this is that, the stronger the gravitational field is, the slower the time passes relative to someone who is not affected by the strong gravitational field. These are some of the theories that try to explain time with the help of Physics.
When we were kids we didn't care much about time. We didn't have any regrets or expectations for the future, we enjoyed the present. But things have changed. Now all we do is think about the future and forget to live the present. How can a physical quantity like Time make such an impact on humans? No one has an answer to this question.
I’ll give an analogy to make you understand time in a simple way. Your life is a movie inside a DVD. The entire movie already exists in the DVD but you only observe the present as it plays out, the past becomes a memory and the future becomes an expectation. This means that we are all playing different characters of an extremely long movie that does not have a beginning or an end.
By:
S.R. Parvez Riswan Mohamed
ECE III Year