An event is represented by a set of coordinates x, y, z and t. Spacetime is thus four dimensional.
But we can break this down. Our Universe as we know it has four dimensions: the three dimensions of space (up and down, left and right, back and forth), and one dimension of time that keeps us all ticking along.
The fourth dimension (4D) is currently defined as a hypothetical construct since we live in the third dimension and must predict what the extra-spatial fourth dimension actually consists of. But generally, the 4D space is seen as an extension of the 3D space, providing further ways that objects can move.
Space in our Universe is three dimensional, and when you combine it with time, you get a four dimensional quantity. When it comes to the notion of spacetime curvature, this is what General Relativity refers to.
Four-dimensional space (4D) is the mathematical extension of the concept of three-dimensional space (3D). Three-dimensional space is the simplest possible abstraction of the observation that one needs only three numbers, called dimensions, to describe the sizes or locations of objects in the everyday world.
In fact we can even draw those 3-dimensional models in 2 dimensions like we did before, and let our minds perform two dimensional leaps. It takes some getting used to, but it's not impossible and many people develop a rather good intuition for four dimensions.
“The fourth dimension is kind of conceivable as right angles to the three dimensions we have,” Australian mathematician (and stand-up comedian) Matt Parker tells us in his book Things to Make and Do in the Fourth Dimension. “But we cannot imagine what the fourth dimension is.”
A black hole is actually a four-dimensional object. A black hole extends across all four physical dimensions of the universe. The four dimensions that form the background framework of the universe consist of three spatial dimensions and one time dimension.
The scientists propose that space is 3D because of a thermodynamic quantity called the Helmholtz free energy density.
(While a black hole is a three-dimensional object, its surface has just two spatial dimensions.)
He told Gizmodo, “Physically, we don't have a 4D spatial system, but we can access 4D quantum Hall physics using this lower-dimensional system because the higher-dimensional system is coded in the complexity of the structure.” We ourselves as 3D objects cast a 2D shadow. A 4D object should then cast a 3D shadow.
Our brains cannot visualise how this dimension would actually be situated on a 4-D object orthogonally. Instead, we can represent how humans would comprehend a 4-D shape to look like from our 3-D perspective. We would perceive a 4-dimensional space as a 3-D projection.
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.
Multiverses are also 4 dimensional, meaning that even though Universes are quite far away from each other, despite not moving much, and there being copious amounts in each Multiverse, they still very rarely collide with one another and have a lot of space, whilst moving through 4 axis.
A hypersphere is the four-dimensional analog of a sphere. Although a sphere exists in 3-space, its surface is two-dimensional. Similarly, a hypersphere has a three-dimensional surface which curves into 4-space. Our universe could be the hypersurface of a hypersphere.
Answer: We live in a physical world with its four known space-time dimensions of length, width, height (or depth) and time. However, God dwells in a different dimension—the spirit realm—beyond the perception of our physical senses.
Humans are three dimensional beings.
Objects in 3D space have different lengths, different heights and different widths. Certain theories in physics suggest that our universe may have additional higher dimensions. Humans, being three dimensional organisms, cannot sense or perceive these dimensions.
Because space isn't curved they will never meet or drift away from each other. A flat universe could be infinite: imagine a 2D piece of paper that stretches out forever. But it could also be finite: imagine taking a piece of paper, making a cylinder and joining the ends to make a torus (doughnut) shape.
Some theorists have even argued for more, up to an indefinite number of possible dimensions. Other physicists suggest that experimental results have thrown cold water on the case for higher dimensions, leaving us only with the familiar three dimensions of length, width and height, plus the dimension of time.
From the viewpoint of an observer outside the black hole, time stops. For example, an object falling into the hole would appear frozen in time at the edge of the hole. Inside a black hole is where the real mystery lies. According to Einstein's theory, time and space, in a way, trade places inside the hole.
Well, even though black holes are extreme in many ways, they don't have infinite mass—and it's mass that determines the force of their gravity. Some black holes—known as stellar black holes. —have about the amount of mass that very massive stars do.
A 4-D being would be a god to us. It would see everything in our world. It could even look inside your stomach and remove your breakfast without cutting through your skin, just like you could remove a dot inside a circle by moving it up into the third dimension, perpendicular to the circle, without breaking the circle.
According to Einstein , you need to describe where you are not only in three-dimensional space — length, width and height — but also in time. Time is the fourth dimension. So to know where you are, you have to know what time it is.