Understanding Time - The Temporal Dimension of Time

## Introduction to Time

In one’s day-to-day experience, we are accustomed to working in three **spatial** dimensions: latitude (forward and backward), longitude (left and right) and altitude (up and down). These being spatial dimensions, we are able to traverse them easily: most of us can transverse left, right, forward and backward for the majority of our lives, and altitude, while more limited, can still be accessed through jumping, staircases, vehicles of flight and so on. However, a less obvious realisation is that there is a fourth dimension, a **temporal** one, that of time. It is this dimension that we shall here explore, and reveal some secrets about a desire which perhaps every human has longed after in their lives: the ability to time travel.

## Understanding Time

What is meant by time being the fourth dimension? What is a **dimension**, anyway? H.G. Wells puts it perhaps the most finely, in his famous story *The Time Machine*:

“You know of course that a mathematical line, a line of thickness *nil*, has no real existence… Neither has a mathematical plane. These things are mere abstractions.”

“That’s all right” said the Psychologist.

“Nor, having only length, breadth, and thickness, can a cube have real existence.”

“There I object,” said Filby. “Of course a solid body may have existence. All real things-”

“…But wait a moment. Can an *instantaneous* cube exist?”

“Don’t follow you” said Filby.

“Can a cube that does not last for any time at all, have a real existence?”

Filby became pensive. “Clearly,” the Time Traveller proceeded, “any real body must have extension in *four* directions: it must have Length, Breadth, Thickness and- Duration… There are really four dimensions, three… of space, and a fourth, Time"

Wells has accepted Time as a fourth dimension, and only a few years later, Albert Einstein was to use this in his theories about **spacetime**. These were not only revolutionary theories that rewrote scientists’ view of space and time, but they allowed the possibility of time travel, something impossible in **Newton’s Universe**.