Time, what time is it? Is it time for class already? No, we still have some time. It is time that we have totally forgotten about, and have taken it for granted for so long. But does time really exist? Does the 24 Hours of the day mean anything? Or does 12 months? Time means different things to different people. According to COLLINS COBUILD Learners Dictionary (HarperCollins Publishers Ltd. 1996) time is defined as the measurement we measure in minutes, hours, days, and years. Seems rediculously simple, but does it have more to it?
Time actually have a more scientific meaning, which will later be explained. The basic definition of time comes down to 1. What we measure in minutes, hours, days and years. 2. Time is what we use to specify a certain point in the day or refer to the period which something has been happenining. (Stephen Bullon TIME Collins Cobuild Learners Dictionary 1999 Pg 1155) From that definition, how long is a day? It is the amount of time taken for the earth to rotate its axis once, containing two 12hour periods.
Telling the difference between the two periods, the notations AM and PM are used (Ante and Post Meridiem). We cannot literally see or tuch time, but time seems to be all around us, from waking up with an alarm clock to watching your dinner eaten away. However, reversing this process can be another concept that raises many questions. As we all are living, we are also time travellers, since time goes by as we live our lives day by day. But since this topic seems to capture our vivid imaginations, it has also become the origin of many science fiction books, movies and even cartoons.
The idea of time has been thought of for so long yet, but he first evidence of the existence of time appeared in Homers Iliad. In this historical Greek epic, Homer stated Now Dawn the saffron-robed was spreading over the face of all the earth. Homer mentioned the start of a new day allowing us to know that the idea of time has been around even before 700BC. In early years, people used to record the beginnings and ends of seasons and noticing that they do come in cycles. With the advancement of astronomy, Ancient Greek started to utilize heavens and stars for designing calendars.
Eventually, Plato, an Italian scientist, stated The Sun, Moon, and planets were made for defining and preserving the numbers of time. Time has always been thought of as a property that could never be changed, but as the human intelligence grew, time also becomes a property possible for manipulation. If any of you are a fan of science fiction, then you should have noticed that the word ‘relativity’ plays a great part in the genre. For example, pepople on Star Trek are always talking about travelling at the speed of light and time dilations.
Both of these are principles based on the theory of relativity. In his theory, Einstein stated that: “Any object (such as the center of the solar system) is a suitable frame of reference, and the motion of any object can be referred to that frame. ” This means that each object can have different motion depending on the point of reference we pick to observe the object from. From this we can conclude that if we see the sun moving around us, we can either see it as, the sun is moving around the earth or the earth is moving around the sun.
Further more, if a person A is running at 1m/sec towards another person B who is standing still, person B standing still will see person A with a speed of 1m/sec. In the same way, person A will see person B approaching him at a speed of 1m/sec. On the other hand, if both were travelling at 1m/sec towards each other, each will see the other person travelling at a speed of 2m/sec. relative to themselves. However, Einstein also stated that anyone should be able to measure the speed of light to be the same value no matter where they take their point of reference to be.
This is the key to his theory of relativity where he utilizes light as an arguement to explain the manipulation of time. To give another example of relativity, which was also stated in Einstien’s theory of relativity, imagin a person dropping a ball on earth. The ball would accelerate at a rate of 9. 8 meters per sec. to the ground. Now imagin the same situation in a spacecraft floating in space with no velocity nor acceleration. The ball would not be falling. Accelerating the carft by 9. 8 meters per second, the ball would drop from the person’s hand with an acceleration of 9. meters per second as well, these two situatoins are just so identical. The person’s feet will feel the exact same thing both on earth and on the carft, an acceleration pressed between the feet and the floor of 9. 8meters per second. Now, for time manipulation. Imagine a spacecraft, travelling at the speed of light passing an astronaut in space. In this craft, there is a lamp that keeps the time. This lamp shines a beam of light onto a mirror reflecting it back to the source, time taken is then recorded. The seperation between the source and the mirror is 0. 3 meters. Meaning the total distance travelled by the light is 0. meters. With respect to the pilot, the light travels forth and back in 2 nanosec. (Time = distance / speed of light). Having another observer outside the craft, the astronaut will see the light as moving in a vertical as well as horizontal path, making the path longer. This way, the total amount of distance travelled by the light increases to 1 meter. This results the time taken for light to return to the source to be 3. 3 nanosec. Instead of 2 nanosec. From this principle, Einstein showed that once travelling at the speed of light, time tends to go slower than other objects taking reference of that time.
