Scientist, philosophers, and mathematicians throughout the ages have tasked themselves with answering questions such as: what is the meaning of life? what happens after we die? I would like to propose a question like these. What is time? Is time an absolute value? Or does time change depending on how we look at it? In other words, is a second the same for everyone, regardless of their perspective? Well, as it turns out, the answer to this question is no. Rather, time is relative; time slows down for objects approaching the speed of light. Einstein introduced his Theory of Relativity in 1905.
What is special relativity? Special relativity can be explained as this: The laws of physics are the same in all inertial frames, and the speed of light is the same for all observers. Time slows down for objects in motion. While this effect is not noticeable in everyday experience, it becomes apparent at speeds approaching the speed of light. The theory of relativity is used to account for observations from different perspectives. For example, objects appear to be smaller when they are viewed from a distance.
Additionally, motion is relative to the perspective of the observer, as objects in a car appear to be still from the perspective of within the car. In the 1970s, scientists did an experiment on the effect of speed on time. They put clocks on fast-moving planes and had them fly around the earth. When compared with the same clocks sitting on earth, the clocks on the planes slowed down. In other words, not as much time had passed on the planes. Once again, time slows down when you’re going really fast. How can time slow down at really fast speeds? To answer this question, we need to consider how we measure time. Time is measured by the observation of repeating events.
All clocks record time with some repeating event, such as a pendulum moving back and forth in a grandfather clock. As long as your clock is not moving, the light will move the same distance between the mirrors with each pass. However, if the clock moves, the beam of light will travel a greater distance with each pass between the mirrors. If we accept that each pass of light between the mirrors is the same unit of time say, a second, for example then the same unit of time now takes longer to pass when the clock is in motion. This slowing of time at high speeds is referred to as time dilation.
It is important to note that time dilation is relative to the perspective of the observer. In other words, if you were to travel in the spaceship with the clock, you would notice no time dilation. Everything would seem normal to you. From your perspective, the beams of light would be traveling back and forth between the mirrors just as if you were sitting still. However, from a stationary perspective, time slows down.
In other words, only the stationary observer observes time dilation in the moving ship. In conclusion,