30 Oct 2011


A Layman's Explanation of Time as the 4th Dimension

This is something I've been pondering for some time and I think I've finally worked out a simple way to explain how time can be seen as the fourth dimension. Don't worry, there's no maths involved in this explanation, just strategic examples.

General Stuff:
In the following examples, I will split the dimensions used into two categories, Base and Stack dimensions. This is NOT any kind of official naming, it's just what I use. The difference between them is basically that if you strip away only the stack dimensions of an object, you can still see what it is but if you take away a Base dimension, the object becomes partially or wholly unrecognisable. This will become much clearer in the examples, believe me.

Example 1: An animated GIF Image
This also applies to a film and basically any moving image. Anyway, an animated GIF is basically a series of pictures, so in this example the 1st (length) and 2nd (width) are the base dimensions (because if you take one of them away, you can't really tell what it is) and the 4th (time) is the stack dimension, as the 2-dimensional images are cycled through over time. The easiest way to visualise this is a flickbook, where the 2D images are literally stacked and then flicked through successively. Therefore you could argue that a GIF/Film is a 3-dimensional image utilizing the 1st, 2nd and 4th dimensions.

A specific example of this is a GIF I made when I was messing around with photoshop's animator tool. It was a large square with a red value which increased along the 1st dimension (x, across), a green value that increased across the 2nd dimension (y, down) but then I was stuck. How could I make it gradient through blue? The image was 2D not 3D, but then I thought of making it animated, effectively substituting the 3rd dimension (depth) for the 4th (time) to create a 3-dimensional gradient.

Example 2: A hologram
A still hologram would be 3-dimensional, utilizing the 1st, 2nd and 3rd dimensions, simple enough (1st and 2nd are Base, 3rd is Stack. Though you could say that any of the 3 could be Stack with the other two being Base, giving a cross-section in any of the 3 axes). But a moving hologram could be said to be 4-dimensional, utilising time as an extra Stack dimension containing a series of 3-dimensional holograms.

I've found this idea very useful when dealing with multidimensional arrays whilst coding, where an array can have up to 32 dimensions. I suppose I should point out that in computer terms, an animated GIF may be put into a 4-dimensional array, not a 3D one, with the extra dimension holding the data for each pixel (x position, y position, colour, etc.) though it is perfectly possible to use a 3-dimensional array and just hold the colour value for each pixel and instead use the dimension indices (i.e. the colour-value's position in the array) to hold the x, y, and t values.

I hope this may one day possibly help some person who is struggling to understand why time is the fourth dimension. Unless of course it isn't and/or this is a load of bull.

Maybe I'll design a program to demonstrate all this...

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