In Physics,
a dimension can be defined as
the magnitude of something in a particular direction.
All the things that surround us
are made up of three dimensions.
These are known as three dimensional or 3D objects.
To know what science says about fourth dimension,
we need to understand the first three dimensions.
For example, take a sheet of paper.
Then, place a dot on the paper.
A dot does not have a direction or a magnitude.
So, we can conclude that
this dot does not have any dimensions.
Let's call this a zero dimension (0D).
Next, from this dot
draw a straight line along the x-axis.
Now, we can measure the length of this line.
So, we can say that this line has only one dimension.
This is called a one-dimensional object or 1D.
Next, from this line,
draw lines on both ends along the y-axis
and convert this into a square.
Now, for this square,
we can measure both its length and width.
As we are able to measure both it's length and width,
now we can say that this square has two dimensions.
These are called two-dimensional or 2D objects.
Next, from this square,
draw lines along the z-axis and convert this into a cube.
Now, we can measure not only its length and width
but also its height.
As we can measure its length, width, and height,
now we can say that this cube has three dimensions.
These are called three-dimensional or 3D objects.
Similarly, objects that we see around us
have length, width, and height
making them three-dimensional.
In 1905,
Albert Einstein published his
Special theory of relativity,
which considers time as the fourth dimension.
Let's take a look at this cube again.
As long as this cube is stationery,
we can pinpoint its position along x,y and z-axis.
But, what if this cube starts moving?
How can you pinpoint its exact position?
In order to say the position of this moving object,
Einstein introduced a dimension called "Time"
into this 3D space.
You may wonder how can "Time" be a dimension?
For something to be a dimension,
it must have a direction and a magnitude.
Similarly, time can be measured (ex: seconds).
At the same time,
time always flows in the forward direction.
So, Einstein took time as the fourth dimension.
Now, with the help of time,
we can pinpoint the exact location of this moving cube.
For example,
we can say that at 8:00 am
this cube was at a particular downward position (x,y,z)
and at 9:00 am
it was at an upward location (x,y,z)
with the help of time.
While the first three dimensions
including line, square and cube
are all geometries,
how can the fourth dimension alone be just "time"?
According to Albert Einstein's space-time continuum,
time is the fourth dimension.
But in mathematical geometry,
the fourth dimension is a shape.
To understand the geometry of the fourth dimension,
we need to look at the first three dimensions
from a different perspective.
Let's come back to the dot.
We know that a dot has no dimensions.
The line that we drew from this dot has 2 dots.
A dot at the start of the line
and a dot at the end of the line.
The square that we drew from this line
has lines on all of its 4 sides.
The cube that we drew from this square
has squares on all of its 6 sides.
Let's say this in a more simple way.
The first dimension has 2 zero dimensions.
The second dimension has 4 one-dimensions.
The third dimension has 6 two dimensions.
If we follow the same order,
then the fourth dimension should have 8 cubes.
The fourth dimension should have 8 three dimensions.
If we draw according to this,
this is the shape of the 4th dimension.
This shape is known as Tesseract.
A Tesseract has 8 cubes in it.
In geometry, as we increase the number of dimensions,
their shapes will get more and more
complicated to understand using our eyes.
Share your thoughts about the fourth dimension
in the comment section below.
Thanks for watching.
