hey guys.
this is space train.
your daily express till the edge of the space.
and today we will talk about, dimensions.
grab your tickets and lets go.
Ask someone to name every dimension they know of and they'll likely list the following:
length, width, and depth.
They might also add time if they're thinking outside the three-dimensional box.
But asking a string theorist, "How many dimensions are there?" would elicit a very
different response.
According to this branch of theoretical physics, there are at least 10 dimensions of space,
most of which are impossible for humans to perceive.
what is a dimension?
Dimensions are the metrics that physicists use to describe reality.
Sounds broad, right?
Let's start with the three dimensions most people learn in grade school.
The spatial dimensions—width, height, and depth—are the easiest to visualize.
A horizontal line exists in one dimension because it only has length; a square is two-dimensional
because it has length and width.
Add depth and we get a cube, or a three-dimensional shape.
These three coordinates are used to pinpoint an object's location in space.
But space isn't the only plane we exist on; we also exist in time, which is where
the fourth dimension comes in.
Once we know a dot's altitude, longitude, latitude, and position in time, we have the
tools needed to plot its existence in the universe as we know it.
But some physicists who subscribe to string theory argue there's more to reality than
the observable universe.
String theory, also known as "superstring theory," aims to unify two main theories describing
how the universe works: general relativity (which applies to very large objects) and
quantum mechanics (which applies to very small ones).
In a four-dimensional universe, this theory wouldn't be possible, but once scientists
tweaked the math to include 10 dimensions—11 including time—their equations worked.
After coming up with a theory that hinges on the existence of 10 space dimensions, string
theorists then had the job of explaining where those new dimensions were hiding.
Their answer: They are just as real as the "big" dimensions we can see, but the extra
dimensions are curled up so tightly that they're too small for us to notice directly.
we will try to visually show how all of this 10 dimensions look like.
The first dimension, as already noted, is that which gives it length (aka. the x-axis).
A good description of a one-dimensional object is a straight line, which exists only in terms
of length and has no other discernible qualities.
Add to it a second dimension, the y-axis (or height), and you get an object that becomes
a 2-dimensional shape (like a square).
The third dimension involves depth (the z-axis), and gives all objects a sense of area and
a cross-section.
The perfect example of this is a cube, which exists in three dimensions and has a length,
width, depth, and hence volume.
Beyond these three lie the seven dimensions which are not immediately apparent to us,
but which can be still be perceived as having a direct effect on the universe and reality
as we know it.
Scientists believe that the fourth dimension is time, which governs the properties of all
known matter at any given point.
Along with the three other dimensions, knowing an objects position in time is essential to
plotting its position in the universe.
The other dimensions are where the deeper possibilities come into play, and explaining
their interaction with the others is where things get particularly tricky for physicists.
According to Superstring Theory, the fifth and sixth dimensions are where the notion
of possible worlds arises.
If we could see on through to the fifth dimension, we would see a world slightly different from
our own that would give us a means of measuring the similarity and differences between our
world and other possible ones.
In the sixth, we would see a plane of possible worlds, where we could compare and position
all the possible universes that start with the same initial conditions as this one (i.e.
the Big Bang).
In theory, if you could master the fifth and sixth dimension, you could travel back in
time or go to different futures.
In the seventh dimension, you have access to the possible worlds that start with different
initial conditions.
Whereas in the fifth and sixth, the initial conditions were the same and subsequent actions
were different, here, everything is different from the very beginning of time.
The eighth dimension again gives us a plane of such possible universe histories, each
of which begins with different initial conditions and branches out infinitely (hence why they
are called infinities).
In the ninth dimension, we can compare all the possible universe histories, starting
with all the different possible laws of physics and initial conditions.
In the tenth and final dimension, we arrive at the point in which everything possible
and imaginable is covered.
Beyond this, nothing can be imagined by us lowly mortals, which makes it the natural
limitation of what we can conceive in terms of dimensions.
There are various versions of string-theory equations describing 10-dimensional space.
However, in the 1990s, a mathematician named Edward Witten at the Institute for Advanced
Study in Princeton proposed that String Theory could be simplified if we glanced it from
an 11-dimensional perspective.
This theory is called the M-Theory.
What's more, according to the Bosonic string theory, there are up to 26 dimensions.
if you want to learn more about string theory, watch our previous two episodes.
you can find links down below.
However.
all of these extra dimensions are beyond our vision.
we have no evidence that can prove they truly exist.
but that does not stop scientists have some fun, and make our already complex world, even
more complicated.
don't forget to comment, what do you think, how many extra dimensions are there, or do
they exist at all.
There are lots of questions left, so don't space out and live some space in your brainfor
answers.
I hope you enjoyed this video, if you want to see more,
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if you are still here, grab your knowledge and get out of my train.
For more infomation >> grown-ish Season 2 | Sneak Peek: Is Something Off Between Zoey and Luca? | Freeform - Duration: 0:52. 
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