Physics Insight

Hyperspace: The Role of Higher Dimensions in Modern Physics

By: Lucy O'Shea - Researcher

What if the reality we experience is only really a fragment of the big picture? What if, just outside our perception, there’s dimensions that shape the fabric of our universe? Up until Einstein published his famous theories of relativity, we believed that the universe could be described entirely in the three dimensions that we experience - width, length and depth. However, physics has progressed so much since then, and we have now discovered whole branches of it that are built on the concept of multidimensional “hyperspace”. 

Hyperspace is the space that exists in higher dimensions - any dimension higher than the three we can experience. This may not just be a mathematical abstraction, but something concrete we must fathom to truly unify physics. Understanding higher dimensions might be the key to unlocking the secrets of the universe, but to even begin to comprehend them, we need to have a strong foundation of what it is to experience dimensions at our level and lower. 

Imagine a 2D world - every person is a flat shape, and all these flat shapes see is lines. These lines represent objects on the same plane as it. Picture yourself at a table with any number of objects on it. When you’re at eye level with the table, the slither of space just above the table is what a 2D creature would see. This slither of our world would be the entire universe of any 2D being. 

Now imagine telling these 2D people that there’s a third dimension - some of them might believe you, but they could never experience it for themselves. The only direction they can move their eyes is left and right. They couldn’t look up or down, no matter how hard they tried. You could try to prove the existence of this mystical third dimension by moving a sphere through the plane of their existence - they would see the line of a circle appear, get larger, get smaller and then disappear again. You could also try describing their world to them - from a bird’s eye view, you would be able to see everything inside their 2D rooms without physically going inside them, and take objects from their 2D square boxes without ever opening them. 

All of these concepts can be translated to 4D hyperspace. We all exist in the 3D equivalent of a plane, and we cannot see into the fourth dimension no matter how hard we try. If the 4D version of a sphere went through the “plane” of our universe, we would see a 3D sphere appear in the air, get larger, get smaller and then disappear. If a 4D creature existed, we would see them as extraordinary. They would be able to reach into a closed bag and take an item from it without ever going through any of its fabric “barriers” - us 3D humans would see nothing. More disturbingly, they would be able to see what we perceive as the inside and outside of all objects - including people - at the same time. 

Every time we go up a dimension, the objects in the higher dimension gain the ability to manipulate lower dimensions in these ways. A 2D land would be utterly under the control of a 3D creature, and 5D beings would seem omniscient in a 4D world. 

Apart from the multidimensional creatures and beings, all of this is being used in current physical models to explain what may be happening in the 3D universe we perceive. Just as people in two dimensions would find it impossible conceptualise the third dimension, we have trouble comprehending the fourth dimension. However, a strong understanding of the fourth and higher dimensions is vital to modern physics. 

Einstein’s theory of relativity revolutionised physics by describing time as another space dimension, and analysing how the resulting 4D universe called “spacetime” would behave if this were the case. Rejected by many acclaimed physicists at the time, his theories were eventually accepted in scientific communities because they described certain phenomena in the universe (such as the orbits of planets) to a much higher accuracy than classical models built on Newton’s laws. 

In a relativistic universe, the spacetime continuum contains not just the universe, but everything that ever has or will happen in it. A sphere expanding and contracting in space as we see it would be a 4D hypersphere in spacetime. In black holes, this flips around - instead of three space dimensions and 1 time dimension, we would experience one space dimension and three time dimensions. We can’t even begin to imagine what this would be like! 

Multidimensional concepts are also being applied to quantum physics as a framework for understanding the properties of fundamental particles - particles so tiny that some of them make up protons and neutrons. These particles have a fixed number of properties that can each be thought of as a dimension of their own. When you see each particle as a point, you create perfect multidimensional shapes that could explain our universe. With a whopping eight dimensions, we can see every particle we’ve already discovered, and also predict the existence of 20 new particles that we haven’t discovered. 

The most common application of hyperspace in physics is to the field of string theory. Instead of using the point-like particles of quantum physics, string theorists describe the universe in terms of 1 dimensional strings. String theory was originally created in 1969, when theoretical physicists realised that they could incorporate all four fundamental forces - the interactions between particles responsible for all motion and change in the world - into the vibration of 1D strings. However, the equations used to describe these strings led to a number of discrepancies that could only be solved by working with more than our three spatial dimensions. In the last 30 years, string theory has gone from 3 dimensions, to 9, 10 and to some variations with 21 and 26 dimensions. However, some believe that string theory is fundamentally flawed. Rather than creating a model and testing it against observations, string theorists made observations and continually updated their model so it fit against existing data. However, if we take it as a conceptual framework rather than physical reality, we can use it as a powerful tool with the potential to make highly accurate predictions of the universe. 

While we can scarcely imagine what hyperspace would be like - many of us have trouble visualising three dimensions, let alone four - we can describe it and the many models that rely on it through maths and computing. High level supercomputers are already at work modelling 4D spacetime and the multidimensional worlds of string theory. The application of higher dimensions to physics has only picked up in the last 100 years, and who knows what we might discover if we continue to apply the insights of geometry and pure maths to deepening our understanding of the universe.