The fourth dimension is not timeEinstein himself said so. You’re welcome to disagree though, once you’ve made a more important discovery than the theory of relativity.

So… what’s the big deal about it? We already have length (the first dimension), area (two dimensional shapes), and volume (3D objects). It’s served as pretty well so far. Plus, we can’t really see the fourth dimension, can we?

We can’t see the fourth dimension, but we can certainly visualise it. Think of it like this:

  • 1D: a line
  • 2D: a square
  • 3D: a cube
  • 4D: a tesseract 
A tesseract. Credit: Wikipedia

A tesseract. Credit: Wikipedia

That’s what the fourth dimension looks like – to people who can only see the third dimension (ie, us). The reason why the cube looks distorted as it rotates is because there’s a fourth dimension at play, one that we cannot really see.

Think of how you’d draw a cube for a person who can only see in two dimensions – you can only represent a 3D object in terms of a flat area. You’d need to show that the third dimension exists by contorting or warping the shape in two dimensions (like how the visualisation above contorts the shape of a cube to demonstrate the existence of a fourth dimension).

Mind blown?

Different types of geometry. Credit: The Story of Mathematics

Different types of geometry. Credit: The Story of Mathematics

Time as the fourth dimension

Remember how we said that time is not the fourth dimension?

Well, some hyper-intelligent folk have postulated that time is the fourth dimension, from as long ago as 1908. But to consider time as the fourth dimension, you have to proceed from the assumption that the first three dimensions are non-Euclidean in nature.

Euclidean geometry is what we all learnt in school – that lines between two points remain constant. Non-Euclidean geometry will ignore or relax such rules, meaning that the lines between two points could be curved, or arched. Basically, if you want to consider time as the fourth dimension, then you’ll need to learn a whole different alternate system of mathematics to explain the first three dimensions.

There are multiple geometrical systems that exist, besides the traditional Euclidean one that we all learnt. In different geometrical systems, lines may not behave in the same way that we’ve taught or believed it to.

TL;DR – if you want to think of time as the fourth dimension, then you’ll need to forget all you know about maths and learn a different syllabus instead.

The Tesseract. Credit: Marvel Movies Wiki

The Tesseract. Credit: Marvel Movies Wiki

Tesseracts in movies

You’d probably remember the Tesseract from films in the Marvel Cinematic Universe. In that universe, the Tesseract is a powerful source of energy – in fact, it’s one of the six Infinity Stones, the most powerful objects in the universe.

And when the six Infinity Stones are combined, they will form the Infinity Gauntlet – a magic glove that bestows godhood upon its wielder.

A Wrinkle In Time. Credit: Golden Village Cinemas

A Wrinkle In Time. Credit: Golden Village Cinemas

In A Wrinkle In Time, a tesseract is a fifth-dimensional phenomenon similar to folding the fabric of space and time, allowing people to move from point to point. Conventional wisdom holds that the shortest distance between two points is a straight line – but a tesseract is a gamechanger because it’s an even shorter distance between two points (since you’re effectively “folding” the straight line), allowing for near instantaneous transport between two places.

Phew! Who’d have known that there was so much backstory behind the tesseract?

A Wrinkle In Time. Credit: Golden Village Cinemas

A Wrinkle In Time. Credit: Golden Village Cinemas

If you’re not sure what the fourth dimension is – look no further than A Wrinkle In Time! The second movie adaptation of the beloved children’s book (don’t ask about the first movie adaptation, you’ll regret it), the film sees a bright young girl embarking on a quest to find her long-lost scientist father. Along the way, she discovers that tesseracts are real, giant evil brains are real, and that love conquers all.

Giant evil brains? Fans of the book will know exactly that IT means, and the rest of you will just have to watch A Wrinkle In Time to find out!


Credit: Giphy, The Story of Mathematics, Wikipedia, Marvel Movies Wiki, Golden Village Cinemas