Transcript
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The speaker introduces dimensions by comparing one-, two-, and three-dimensional worlds using simple visual examples. This leads into the question of what a fourth dimension could be.
Imagine that this folder is a dimensional plane.Now, assuming that it has no height and no depth, what would this mean?It would mean that it's a one-dimensional world.So, if hypothetically an organism was living inside of it, it would only be able to move in a linear path forward and backwards in a straight line.Now, if we go to the second dimension, we have two dimensions.We have width and we have length.So hypothetically, if an organism lived inside of here, then it would be able to move up, down, left, right, and anywhere else in between.And a two-dimensional world is comprised of an infinite series of one-dimensional worlds stacked upon each other.Just as our three-dimensional world, which has depth and length and height, is comprised of an infinite series of two-dimensional worlds.So this now that I have stacked many folders upon each other.
We have three dimensions.We have depth, we have length and we have width.Now what happens if you keep going on from here on out?We would have a four-dimensional world.But what exactly is a fourth dimension?In order to understand this, we need to understand how dimensions are perceived.
Explains that we perceive the world in a limited way, using examples like spheres and moving objects to show how dimensional perception works. The section builds toward the idea that a four-dimensional being could see through our 3D world.
We live in the three-dimensional world.But despite that, we actually view things to be two-dimensionally.Take a perfect sphere for example.If you're looking at a sphere, it looks just like a regular two-dimensional circle.The only way that you can tell it's a actual sphere instead of a circle is because of the hues of light on it.So, just like in a two-dimensional world, if a um organism in the two-dimensional world was looking upon a circle, it would the light would make it appear to be lighter at one end and darker in the middle.Also, if you if an object is moving farther closer and farther away from you, you don't actually perceive that it's getting closer and farther away, you see that it's getting smaller or larger, and then you assume that it'sgetting either farther away or closer.But let's say an object was to grow in perfectly equilibrium so that it was growing at the same speed that it was shrinking as you move it farther away.
then you would not be able to tell without any lights or uh if there were details on the object that it's moving or growing at all.You may have assumed that since we perceive things to be in two dimensions that a two-dimensional uh organism would see in one dimension.So, as we're watching this uh rubber band expand, as it moves farther away from this little uh organism in the two-dimensional world, it's does not actually perceive anything is happening to it because it's growing at the same speedthat it's moving farther away.But since we can actually see it from the three-dimensional world and perceive things to be in two dimensions, we can see things to for how they actually are.The reason that the two-dimensional organism doesn't see things the way they really are is because the two-dimensional organism sees things in one dimension just how we threedimensional creatures see things in two dimensions.
So, in a way, we don't really see our world the way it truly is.A four-dimensional creature, however, seeing our three-dimensional world in three dimensions would be able to see through things.You'll be able to see absolutely everything just as we could see if there was uh several organisms spread along a 2D um environment on your floor.You would be able to see inside houses.You would be able to see inside of people.So if a two-dimensional world, a flat surface is just made of an infinite amount of uh lines, then the 3D world is just made out of an infinite amount of planes.So the 4D world logically is made out of an infinite amount of 3D objects though they're not just put together like um you would like building blocks.It's that's not how the 4D world is.That would just be 3D again.
So in order to understand this we need to understand the logical progression of mathematics in our world.
Uses mathematical progression from line to square to cube to explain how a four-dimensional basic shape, the tesseract, is formed. It also notes that higher dimensions beyond four are theoretically possible.
Imagine that this connects piece represents the first dimension.It's simply a straight line, which is basically what the first dimension looks like.And if you add three more of these straight lines and connect them to so that adjacent sides are perpendicular and opposite sides are parallel, then you have the basic shape of the second dimension.You have a square.Now if you keep going from here and you add four add it so that there's a total of four squares and all adjacent sides are perpendicular and all opposite sides are parallel then you end up with obviously acube.So if you tried to keep going from here and you would have a fourdimensional basic shape you would have a what's called a tesseract.Now I cannot show you a test raact but you need to understand that it's basically four cubes that are within each other that um have all adjacent sides perpendicular and all par and all opposite sides parallel yet there
are three lines connect four lines connecting to each vertex.So a tesact would look somewhat like this picture.Now that that's not exactly what it looks like because this is a twodimensional depiction and obviously not all the lines are straight.So I cannot show you what a cessoract actually looks like because we cannot perceive things in the third dimension.You cannot even imagine what a tesseract looks like.You cannot physically you cannot in your mind picture the fourth dimension or a fourthdimensional shape.And you can keep going on from the fourth dimension even.You can go to the fifth dimension, the sixth dimension, the 71st dimension.It doesn't matter.Theoretically, there are an infinite amount of spatial dimensions.
Addresses the common misconception that time is the fourth dimension and argues against it. The speaker uses relativity and time dilation to show that motion can affect time without making time a spatial dimension.
A common misconception of the fourth dimension is that the fourth dimension is time.Now, while some argue that by going forward and backwards in time, if you move forward the same distance and backwards the same, then you would end up in the same place you started, just like in the fourth dimension.And while that may seem logical, if you think about it, it really doesn't make sense.If you imply that the fourth dimension is actually time, well, first of all, time is not spatial.There's a difference between space and time quite obviously.And assuming that all dimensions are according to a pattern, then that doesn't really make sense either because saying the fourth dimension is time, every dimension has time in it.So that would mean that the fourth dimension is special in some way, which doesn't really make any sense.Another reason this doesn't make sense is that we very very very slightly travel through time whenever we move due to the distance um that light takes to get to our body.
If a group of astronauts were to get in a spaceship and they were to go very very very close to the speed of light, then they would and they they went around in this um impossible nearly the speedof light spaceship for a few months and then afterwards they returned to Earth.They would find that Earth had actually progressed a few years.So they had moved forward in time by moving that quickly.
Discusses the idea that dimensions may be slightly curved and nested within one another, leading to speculation about an infinite hierarchy of dimensions. The video ends with the speaker reflecting on the limits of this theory and thanking viewers.
Another interesting concept involving the fourth dimension is that many physicists and even mathematicians uh may say that the dimensions are very very slightly curved because if you really think about it nothing can be truly absolutely infinite.So imagine that a the first dimension the line is just very very slightly curved so that after a very long time it will um end up creating a circle.So um as suggested by many physicists if you keep going in the same direction then you will end up where you are where you started after a very very long amount of time obviously and the same thing wouldhappen to the second dimension.If it's just a square and then you extend it very very slightly in a curve then it will eventually make a sphere.And the same thing happens in our dimension except it will form a very very slightly curved um third dimension which will form a four-dimensional universe basically.
So what this kind of means is that our three-dimensional world is within a four-dimensional world and a four-dimensional world is within a fifth dimensional world and so on.Now, I did say that nothing can be truly infinite.But if this is true and a dimension is really within another dimension within another dimension within another dimension, then I'm implying that there's an infinite amount of dimensions, which is the only problem I really have with the theory.I'm not sure if it ever stops or if infinite infinity is really even possible.We don't know that.Thanks for watching my video and I hope this gave you a better idea of what the fourth dimension is.