Time is a dimension (like space), but it behaves a little differently than space. Time is one of the most difficult properties of our universe to understand. With clocks we measure numerical order of material change. This numerical order is the only time that exists in a physical world. With this approach all immediate information transfers of quantum physics are explained in a more appropriate way. Time is usually defined by its measurement, that being simply what a clock reads.
We can’t see objects in the past nor those in the future, we only see those in the present moment of time. We only exist in the present and can never experience the future or the past because they act at right angles to the present. Time is an illusion created by the changing universe, or changes of every consciousness. The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems.
Physics often requires extreme levels of precision in time measurement, which has led to the requirement that time be considered an infinitely divisible linear continuum, and not quantized (i.e. composed of discrete and indivisible units). The concept of time generally used is that of absolute time (also called Newtonian time), is independent of any perceiver, progresses at a consistent pace for everyone everywhere throughout the universe, and is essentially imperceptible and mathematical in nature. In the early 20th Century, relativistic time has become the norm within physics. This takes into account phenomena such as time dilation for fast-moving objects, gravitational time dilation for objects caught in extreme gravitational fields, and the important idea that time is really just one element of four-dimensional space-time. Multiple dimensions may exist and we might never be able to prove it.
The difficulty of visualizing the 4th dimension when you live in a 3D world, is that most people just can’t conceptualize any geometries beyond 3D. Sure there are a handful of mathematicians and theoretical physicists that work with 4D and 5D spaces, but none of them would claim to be able to visualize what it truly looks like. They tend to visualize in projections or by breaking down their dimension into slices, where they take their big object, and flatten out one of the dimensions so that it fits in 3D.
A point has no spatial extent it is a 0D space, but a point can be stretched out into a line, to become a 1D space. If you slide this 1D line sideways, you can build a 2D plane. This 2D plane can be swept up in order to build a 3D space. You can think of this like being a stack of an infinite number of really thin 2D slices, which can be bundled together to make this 3D space. However the 4th dimension doesn’t have any direction in it, it is sort of like how an ant on a sheet of paper can’t move up or down off of it, because it is confined to the 2D plane of the paper. If we take our 3D space, and just smear it out again, so that we now have an infinite number of 3D ‘slices’, and staple them all together, that is sort of what the time dimension looks like because the time coordinate is instantaneous ‘slices’ of 3D spaces. I like to think of a flip book, where each page has its spatial dimensions, and motion in the time coordinate amounts to flipping forward or backward in the book.
Philosophers have debated the nature of time long before modern physics. But in the 100+ years since Einstein, the prevailing view in physics has been that time serves as the fourth dimension of space, represented mathematically as 4D Minkowski spacetime. Einstein did not interpret time “t” as a fourth dimension of space. Space is not 3D + T, instead, it is 4D. Simply stated, the first three dimensions are used to specify an object’s location/movement in space (forward-backwards, left-right and up-down), while the fourth dimension locates its position in time. All four dimensions are used to specify completely the location or dynamism of an object in space. Collectively the four dimensions are inseparably interlinked and known as space-time.
We are living in a three dimensional world, one that contains length, width and height, so we are unable to see the fourth dimension, as our physical world is constructed within these three physical dimensions only. We might feel or imagine time’s presence, but we can never actually detect it with our three-dimensional senses, because it extends beyond our universe. We can only perceive time, this fourth dimension as memories lodged at different intervals, with the result we perceive time moving in one direction which is forward. A demonstration of four dimensional space-time’s inseparability is the fact that we cannot look into space without looking back in time, like when we see the Moon as it was approximately 1.2 seconds ago and the Sun as it was about 8 minutes ago and so on.
Speed = distance ÷ time; therefore, if the speed of light is to remain fixed then it will be necessary for the distance and time in the equation to change. What actually happens is that time and distance are ‘relative’ to one another, and as we travel close to the speed of light, distances become shortened while time is lengthened. This is explained in Einstein’s Theory Of Special Relativity. The reason why time is regarded as the 4th dimension is that in relativity, we have to include the time coordinate in describing events fully in space along with the time, called the space-time coordinate.
People say that time flies when you are having fun, but the frog said that time is fun when you are having flies.
Written for Sammi Cox Author Aspiring Weekend Writing Prompt #33 – Time.