Fourth Dimension — Spacetime
Story of 4D-beings and Spacetime
Our understanding of the universe did become a reality when we got an idea of length, width, and height. When we were done with these dimensions, we wanted more. We didn’t want to be stuck in the walls of the three-dimensional world. We spread the wings of our imagination, we searched for the thing that was responsible for changing the position of these dimensions. We looked for it in every direction, dimension to be precise. But didn’t find anything. We tried with calculations. Those calculations gave evidence of the presence of another dimension.
Our search ended when our sight fell on our wrist. Ahh…that’s it! A watch! Time! we told ourselves. That hint was enough for us to imagine the fourth dimension as space-time. That is to say, both space and time are interwoven in a 4D fabric that we call “space-time”.
Newton defined time to be universal — it doesn’t matter where you are in the universe, time flows the same for everything. Albert Einstein thought time to be non-universal or non-absolute.
From that day onwards, there has been continuous research in this field. One theory led to another and to another and so on. Albert Einstein himself worked on the dimension of time and came forward with the Theory Of Relativity, that changed the future of Physics. Further, Einstein predicted spacetime and matter affect each other.
What exactly is this fourth dimension and how can it change our perspectives? I know, you’re eager to dive into the world of magic — the world of the fourth dimension. For better understanding, we’ll divide the fourth dimension into two parts: first, dealing with how things or beings would experience the fourth dimension(under the heading — Objects In Fourth Dimension); the second part would explore the nature of the fourth dimension and the intermingling of other concepts related to it(under the heading — What Is Fourth Dimension?).
Let’s take a deep plunge together. Here we go…….
Objects In Fourth Dimension
Now, both of us have landed in the fourth dimension. You know what to do now — “In Rome do what the Romans do”. Now, here in the fourth dimension do what the fourth-dimensional beings would do. Look around. What do you see? What type of structures are there?
Okay…. Don’t worry! I know you’re confused. You don’t know how to perceive this dimension, right?
Let me help you. Start with things that make you feel awestruck. Start from small ones, the shapes. Just move your eyes slowly as if you’re looking at the Pyramids. Now, concentrate on the repetitive patterns. You’ll come to know a lot just by watching things change. Just by looking at shapes, you’ll develop your basics.
Flatlanders
The higher dimensions can be easily understood with the help of a sci-fi novel written in the year 1884. This novel changed the perspective of humans — as in, how they perceive dimensions. The novel got famous by the name of “Flatland” written by Edwin Abott Abott. I didn’t write Abott twice by mistake.
Everyone thriving in Flatland is flat. Like its name, the novel is unique in a way that you’d see squares, circles, triangles, living and behaving like real living beings. They have their houses. They are married — a straight line is married to a square and the square’s brother is another square. Every one of them lives in a flatworld with just two dimensions: length and width. They don’t even know about the existence of another dimension. But they’re quite happy in their world, doing everything that a living being would do, but in a “two-dimensional world”. With the lack of a third dimension, there isn’t much. The beings represented by the shapes can only move forward, backward. Our presence in this dimension would be perceived by the Flatlanders as a sort of paranormal activity. They would think us as ghosts or spirits.
What can a fourth dimensional being know about lower dimensions?
Humans can’t understand the fourth dimension. Although they’re always confined within the boundaries of this dimension, they don’t know how to recognise or explain this dimension. A being in this unknown fourth dimension can use this dimension to its advantage. The fourth-dimensional being can understand the psyche, life, environment, and everything related to a three-dimensional being quite easily. — like we can know everything about a two-dimensional world — we can know their secrets like what happens in their lives, and even more(in case we find a living two-dimensional being). The fourth-dimensional being could look inside the deepest ocean, say Mariana Trench, at all the fishes what they’re doing, what they’ve done, or what they’re going to do without even diving in it.
Before jumping to the world of dimensions let’s understand the meaning of a dimension. A dimension is the minimum number of coordinates that are necessary to specify any point in the space.(I know I picked the definition quite late, but believe me, I didn’t want to ruin your momentum. That’s the reason for choosing it late).
Suppose you’re a dot and you can’t move anywhere — you can’t move forward and similarly, you can’t drift backward, not even to left and right. You’re a frozen material. That’s the zero-dimensional version of you.
Now you’ve been transformed into a line, with two points. It’d be the one-dimensional version of you. Suppose a point you drew on the piece of paper, say a dot and it started to come out of the paper and started crawling near you. Unidimensional being thrives but now it has taken the form of a three-dimensional being( apart from length and width it has one added dimension of height as well) object. It has started to haunt you.
What do we mean when we say four dimensions?
The first three dimensions are the dimensions of length, width, and height — called the dimensions of space. The fourth dimension is a unique one, in the way that we can’t perceive it with our senses. It’s the dimension of time or precisely spacetime.
Manipulating the fourth dimension
The first three dimensions can be easily manipulated by a three-dimensional living organism — like moving forward, backward, left, right, up, and down. But the fourth dimension isn’t in our control — it’s beyond our manipulative power. An individual living in the 4th dimension would always have an equally same past, present, and future.
The reason for this phenomenon to take place in the fourth dimension is because time transforms a physical entity in the 4th-dimensional world. In case you move in the future by 2 years in the dimension of time and again move in the past by 2 years, you would have experienced the future and still be in the present.
Once the doors of the fourth dimension are opened for us, we’d be able to sneak into the past and future.
Showing the 4th-dimensional object practically
A tesseract is the four dimensional cube(hypercube). It is a four-dimensional mathematical object with lines of equal length that meet each other at right angles.
A Tesseract is an example, a hypothetical one of a four-dimensional object. So far as we know, in reality, this cube doesn’t exist, it’s just the mathematical version of it projected onto a screen.
What Is Fourth Dimension?
Einstein’s concept of spacetime
Albert Einstein’s concept of a four-dimensional spacetime becomes complex and is only possible when using Minkowski structure instead of Euclidean conception of four-dimensional space.
Minkowski space is more closely associated with Einstein’s theories of special relativity and general relativity.
Einstein believed spacetime isn’t static; it can move away from other parts of itself, that is to say, it can stretch, or it can bend.
Why can’t we perceive higher dimensions?
Certain studies suggest that these higher dimensions are not perceivable because these dimensions are very small and are curled up at extremely small scales. The experiments can’t be performed on such a small scale.
Theories that point at the presence of a fourth dimension
Apart from Einstein’s theories of relativity, there are other theories too that take spacetime into consideration.
Causal Dynamic Triangulation —This theory is a recent approach to quantum gravity. It derives the features or properties of spacetime in a new manner. This theory points out the ever-changing nature of spacetime. It shows that it does not assume any pre-existing arena (dimensional space), but rather tries to show how the spacetime fabric itself evolves. Causal Dynamic Triangulation theory states that near Planck’s scale, spacetime and its structure is changing due to quantum fluctuations.(Planck scale is an energy scale at around approximately 1.22×1019 GeV at which quantum effects of gravity become strong.) Using a structure termed as a simplex, Causal Dynamic Triangulation divides spacetime into small triangular sections.
String Theory —It is the best ever version of the spacetime conundrum. It tries to give spacetime a meaning but at the same time establishes its relation with other entities too. The beauty of string theory is that it unifies everything and gives us a broader picture of universe. It tries to relate both spacetime and matter. It tries to equate the quantum of gravity — the gravitons, with the quantum of matter — electrons. It predicts these are one and the same thing, and can be described as a single entity or a string. The same thing manifests in two different ways. A string oscillating in different ways could be a quantum of spacetime or a quantum of matter.
But there is a problem with string theory as well. In the words of Stephen Hawking, “the problem with string theories is that they are consistent only if spacetime has ten or twenty-six dimensions instead of the usual four!”
How did spacetime emerge?
To understand the concept of spacetime, we’ll start with the pet words of any science lover, “In the beginning, there was nothing, and with a boom(Big Bang)there came everything”. In no moment, an extremely small region in an extremely short duration of time suddenly and instantaneously expands manifold times. The instant that the event of Big Bang took place, both space and time were created instantaneously. The regions of high density in spacetime formed matter, and this matter, in turn, bent the space.
It means “Spacetime itself emerged out of Big Bang”.
In addition to this, the universe expanded much faster than the speed of light. We know it is a violation of every concept of Physics. But believe me, it isn’t. Scientists say that nothing can move faster than the speed of light within the universe, but it isn’t true for universe itself — so the universe grew much faster than the speed of light. Even it is still expanding.
Nature of spacetime
Physicists believe, ‘Spacetime is not fundamental; it’s an emergent description from something else that underlies it’. It means spacetime is a dynamic entity.
It changes shapes, forms and is the most flexible thing ever possible in the entire cosmos.
Recent Discovery in this field
Although, Einstein had predicted the fourth dimension, but he said that it couldn’t be proved. Einstein predicted that massive objects, like blackholes, have effects on the spacetime fabric. He further predicted that these massive bodies when accelerating would be changing the spacetime in such a manner that these would be producing ripples similar to waves. The discovery of gravitational waves has confirmed his predictions. Our experiments especially at Laser Interferometer Gravitational Wave Observatory(LIGO) detected these gravitation waves.
LIGO sensed the undulations in spacetime due to the effects of gravitational waves generated by two colliding black holes 1.3 billion light-years away.
He had theorised that when two massive objects like black holes collide they give rise to gravitational waves. These waves can travel through objects without causing any change.
Another perspective of looking at dimensions
Some scientists believe the four dimensional objects might be the four-dimensional projection of two dimensional information. Not just four dimensions, but some of the scientists believe our three-dimensional reality might also be a projection of information that is stored far away in a two-dimensional surface.
Spacetime is the evidence that everything arises from nothing. Every possible theory of universe would start from spacetime. Beginning of universe is related to spacetime, gravity is an extension of concept of spacetime, and movement of light is also associated with spacetime. This fabric of spacetime is stronger and mysterious than any other fabric, as it contains the entire universe. Understanding about the fourth dimension can help humans to understand everything. In fact, we are entrapped in the spacetime and our understanding of it can set our fetters free. Maybe the roots of Theory Of Everything lies hidden in the fabric of spacetime….
