Time, as perceived in everyday life, is a consistent pulse marking every second of existence. But delve deeper into the realm of physics, and time reveals itself as an unfathomably complex entity.

Albert Einstein’s Special Theory of Relativity shattered the simplicity of the universal ticktock, revealing time as a relative phenomenon. In the fabric of space-time, a second on Earth is not equivalent to a second on a speeding spaceship or in the proximity of a massive object like a black hole.

The closer one gets to the speed of light, the slower time passes—a prediction confirmed by experiments comparing synchronized atomic clocks on airplanes with those on the ground.

The peculiarity of time has been observed: clocks do run slower at high velocities. Physicists, using an analogy of a light clock, have demonstrated that as a clock moves, the time between ticks lengthens.

This time dilation, while negligible in daily life, becomes profound as one approaches light speed. Even our own biological clocks are not immune to these relativistic effects, although we don’t perceive the differences as our frame of reference changes in unison.

Delving into the philosophical implications, theoretical physicist Carlo Rovelli paints time as an illusion—a complex network of events without a true sequence of past, present, and future.

Drawing from the tenets of loop quantum gravity theory and quantum mechanics, Rovelli sees the universe operating without time at its fundamental level, a concept further supported by equations like the Wheeler-DeWitt equation, which describe the universe without temporal coordinates.

In this view, ‘forward in time’ is merely the direction in which entropy increases, a subjective feature of our universe rather than an objective reality.

Despite these revelations, the practicality of time remains concrete within the framework of relativity. Events within the light cone of any point in space-time are causally connected, and their temporal order is invariant.

The distinction between past, present, and future still holds within this domain.

The confusion surrounding Einstein’s stance on time as an illusion stems from non-scientific interpretations of his comforting words to a friend’s widow, not from his rigorous scientific work.

The notion of time as a dimension that one can traverse has tantalized scientists and inspired science fiction. Einstein’s theories allow for the possibility of time travel—albeit only towards the future.

Time travel equations, stemming from the famous E=mc², suggest that as we approach the speed of light, we can effectively leap forward in time.

However, this form of time travel remains a distant reality, hindered by our current technological limitations and the immense energy required to achieve such speeds.