- In physics, the 5th dimension is a microdimension of space too small to see that has mathematical value in theoretical models of the universe, like string theory.
- Experiments at the Large Hadron Collider may find indirect evidence of the 5th dimension if scientists can prove graviton particles are real and disappearing into it.
- In information theory, information is considered the 5th dimension since it shapes our thoughts, behavior, and reality like the other dimensions of space and time.
The 5th Dimension at a Glance
The 5th dimension is a conceptual, unobservable microdimension of space. It’s considered a spatial dimension, like the 3D length, height, and depth we’re familiar with. In theory, it’s a plane of spacetime that’s curved in on itself so tightly, the entire dimension is a loop smaller than an atom. It’s too small to be noticed by humans, and its existence can only be indirectly observed through its theoretical effects on the fundamental forces of the universe (mainly gravity). The 5th dimension is mostly used as a mathematical tool to make sense of various physics models of the universe, like string theory.
The 5th Dimension in Physics & Theory
The 5th dimension was conceived to mathematically unify gravity and electromagnetism into a single force. When Einstein published his theories of general relativity and gravity in 1915, he showed that the force of gravity is actually the result of the spatial dimensions (length, height, and depth) being “curved” by massive objects, like Earth or the sun. In the 1920s, physicists Theodor Kaluza and Oskar Klein speculated that the electromagnetic force was also the result of a curved dimension of space, but one that humans couldn’t see—the 5th dimension. This is called the Kaluza-Klein Theory. In this theory, the 5th dimension is curved so tightly that it’s smaller than an atom. It’s too small to be seen or to interact with massive objects, but can influence subatomic particles and generate electromagnetic fields. Kaluza and Klein believed both forces were generated by the warping of dimensions of space, making electromagnetism a component of gravity. This was important because unifying the fundamental forces could lead to a “theory of everything” (a physics model that combines quantum mechanics with Einstein’s relativity).
Today, the 5th dimension is an accepted part of string theory. The Kaluza-Klein Theory was proven partially incorrect when the strong and weak nuclear forces were discovered (these are also fundamental forces, but they aren’t the result of curved spacetime like gravity is). However, their ideas led to other “theories of everything,” like string theory. In string theory, unbelievably small “strings” of energy vibrate in 10 dimensions of spacetime and influence the fundamental forces. String theory suggests that our 4D reality is an island (or “brane”) in a 10D universe, with the extra 6 dimensions rolled up into sizes too small to observe. Some physicists think that gravity (and its theoretical particle, the graviton) can leak into the additional 6 dimensions, diluting its strength in our reality. This would explain why gravity is weaker than the other fundamental forces. Others believe that unobservable particles from the 5th dimension make up the universe’s dark matter (invisible matter that exerts gravitational force but can’t be seen).
What does the 5th dimension look like?
In theory, the 5th dimension is rolled into a loop smaller than an atom. Estimates say it’s only 10^-33 centimeters wide (that’s 0.0000000000000000000000000000000001 centimeters!). This is completely invisible to the human eye, and smaller than subatomic particles like electrons and quarks. The dimension is also thought to be closed in on itself, meaning there’s no direct, visible “opening” to it.
The 5th dimension can’t be observed, but its influence might be visible. Since the 5th dimension is so small, it’s unobservable on any scale less energetic than the state of the universe at the Big Bang (particle accelerators can get close to this energy level, but can’t match it). However, some theories suggest that ripples or fluctuations in the 5th dimension appear as light or even particles in our reality. For example: Say you’re swimming underwater in a pool on a sunny day. When the surface of the water ripples, you see shadows moving across the bottom of the pool, but not the ripples in the water above you. This is similar to how we might experience diluted or distorted events from the 5th dimension when they “cast shadows” into our 4D reality.
Evidence for the 5th Dimension
Experiments at the Large Hadron Collider may indirectly prove a 5D world. The Large Hadron Collider (LHC) is a massive particle accelerator in Europe, 100 meters (328 ft) below ground. It smashes subatomic particles into each other at staggering speeds and studies the particles that emerge from the collision. In theory, the LHC can create gravitons—the yet-to-be-discovered particle that mediates the force of gravity—and measure if they disappear into extra dimensions as theorized. Collisions in particle accelerators always create balanced events, with particles flying out in all directions. An “empty zone” (detected as an imbalance in momentum and energy) could mean that gravitons existed and quickly escaped to the 5th dimension. It’s possible the “empty zone” could be caused by something other than a dimension-hopping graviton, and careful research is needed to confirm this hypothesis. Gravitons escaping to other dimensions would explain why gravity is weak in our universe compared to electromagnetism and the strong and weak nuclear forces.
The 5th Dimension as Information
In information theory, information itself is considered the 5th dimension. Like space and time, the flow of information influences complex systems—our decision-making, our behavior, our technology, and more. Information doesn’t just describe our reality, but shapes it as well. In physics, fundamental particles like electrons also store and “communicate” information in the forms of thermal radiation, electromagnetic fields, and more when they interact with other particles. By some calculations, stored information even has mass. One stored data byte has a mass of about 1 attogram (one quintillionth of a gram).
What are the first 4 dimensions?
As humans, we perceive 3 dimensions of space and 1 dimension of time. The 1st dimension is length (imagine a straight line, or the x-axis on a graph). When we add the 2nd dimension of height or width perpendicular to the 1st dimension (the y-axis on a graph), we’re able to create 2D shapes. Add a 3rd dimension of depth perpendicular to both the x- and y-axes (the z-axis) and we get the 3D space we live in. Time is widely considered to be the 4th dimension. When something occurs or exists is as important to plotting its existence in the universe as the 3 coordinates of space.
In physics, there's debate over time being the 4th dimension. Some physicists argue that time is intrinsically part of the spatial dimensions—it’s just a numerical order of events happening in a given space. They say time can’t be measured as an absolute physical quantity the way length, height or width, and depth can be. For example, say you’re measuring a car’s speed as it drives down the road. Experimentally, you’re comparing the car’s motion to the arbitrary ticking of a clock to calculate speed. In this scenario, time is just a mathematical value and doesn’t exist independently when you’re not comparing events. Many physicists accept that we live in 4 dimensions of spacetime (rather than 3 dimensions of space plus 1 dimension of time), with time being inextricably woven into what we perceive as space.
What is a dimension?
A dimension is one facet of our perceived reality and our place in it. In our daily life, we’re intuitively aware of our place in the universe through the 3 dimensions of space and the 4th dimension of time. You can “pin” yourself to a point in our reality by describing exactly where and when you are. More exactly, the dimension of a mathematical space or object is the minimum coordinates needed to specify any point within it. Since we live in a 4D reality, we specify where we are with the 4 coordinates of length, width or height, depth, and time. For another example, consider a 1D object like a straight line. There’s only one possible coordinate that could describe a point on the line (a coordinate of length). There is no measurable height, depth, or time to consider. Humans aren’t able to perceive a fifth coordinate that would further specify our point in reality, which is why we can’t “see” 5th dimensional events.
How many dimensions are there?
Some physicists believe there are up to 10 or 11 dimensions in total. Proponents of string theory—the idea that reality is made up of infinitesimal vibrating strings smaller than atoms—need 10 (sometimes 11) theoretical dimensions to make their equations work consistently. Each additional dimension reveals more information about our universe, as well as all possible universes and realities. For example, seeing through to the 5th and 6th dimensions would give us access to a plane of all possible universes that started with the same initial conditions as ours (the Big Bang). Additional dimensions beyond the 6th would allow us to see all possible universes, including those with different initial conditions than ours. The 10th and final dimension would bring us to a point where everything possible or imaginable is covered. There is no higher view of reality from this dimension (that humans can conceive of, at least).
Key Takeaways
The 5th dimension is accepted as a way to tie gravity to electromagnetism. We can’t observe it directly because it interacts on a higher plane of space than we exist, but mathematically, it provides a common “root” for gravity and electromagnetism (which seem unrelated in our existence). There’s little evidence for a 5th dimension, but the Large Hadron Collider may prove its existence through the study of graviton particles. Despite the lack of proof, the 5th dimension is an invaluable tool for physicists working to understand the true nature of the universe.
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