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**im really bored****Member**- Registered: 2005-05-12
- Posts: 76

Im looking for any ideas on how to explain the fourth dimesion to someone in a non mathmatical way

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

I thought a dimension bigger than three was impossible..........

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**justlookingforthemoment****Moderator**- Registered: 2005-05-26
- Posts: 2,161

Width, depth, height and ... * time *

Isn't that a dimension? Like as in time travel?

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

Aha, I see.

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,555

Width x Length x Breadth x Frumth. (Sorry, I just made that up!)

This is actually a very deep and interesting question.

Yes, time is another dimension, but it is not a length dimension.

Likewise the density of something represents another dimension. Pour milk into coffee, and you will see patterns. This pattern is not just in 3D, because the whiteness varies at every point in 3D space, making a 4th dimension: "whiteness".

But if you are talking about a 4th "length" dimension, it requires some imagination.

Perhaps start thinking about 2D vs 3D and then imagine 3D then becoming 4D.

Let's start with a square piece of paper 200mm on a side, then extend it upwards by having lots of other square pieces of paper stacked on top till the stack was also 200mm high. That would be a cube, right?

NOW, if you took that cube and could place lots of other cubes just a "slice" away from each other extending into some other dimension we can't see, then that would be a 4D cube.

(I should point out that the "piece of paper" stack is just to aid the imagination, you can't really "stack" 2D shapes to make them 3D)

Another way to think about it is to take a 3D object and cut it and then look at the resulting 2D shape. Cut across a pyramid and you will see a square or rectangular shape. So someone living in 2D would see the world composed of rectangles, circles, ellipses etc, and have no idea about cubes, spheres, etc. And we who live in the 3D world see spheres and cubes etc, but not the 4D shapes that they are "sliced" from.

What Fun !

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**mathsyperson****Guest**

The fourth dimension is the reason that theoretically an astronaut could launch from the north pole into the depths of the universe and eventually land on the south pole without ever changing direction.

Think of it form a 2D person's point of view. To become a 2D person, get down on the floor as low as you can, cut a slit in a piece of cardboard and put it over your eyes, and somehow restrain your head so you can only lokk from side to side. Also, your not allowed to jump.

Anyway, 2D people can only see in one dimension. For this reason, it is impossible for them to imagine the existence of a third dimension. They live on a giant balloon, which we know is a sphere, but it is so big that they think it is flat. One day, an explorer decides to find the edge of his world and so drives off on a very powerful motorbike in a straight line until he finds it. He is surprised to discover that instead of reaching the edge, he arrives back at his start point (he knows this because he wrote an X with a piece of chalk). He is very confused and doesn't know how this happened, but we know that he just went round in a circle through the dimension that he didn't know existed.

This is exactly the same for us, except that we think that there are only three 'length' dimensions and we can't understand how the astronaut got to the south pole because we can't see the fourth one. There are probably 4D people laughing at our stupidity because of this, but they don't know that there is also a fifth dimension and so on.

Sorry if I have confused anyone with this theory and I would be interested to know if anyone agrees with me or if you all think that I am completely mad.

P.S. I think that this topic would be happier in the 'Dark Discusions' Forum.

P.P.S. I have included some spelling and grammar mistakes to try to tempt Zach back.

**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

Mathsyperson, can I ask something?

Would you not want to consider signing up as a member?

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**im really bored****Member**- Registered: 2005-05-12
- Posts: 76

These are all good ideas and yes I do agree with you mathsyperson. The reason im interested in this topic is just for my own knowledge and curiosity. Right now I am reading something called flatland to try to help me understand more about other dimensions, When im done I will tell about anything interesting I learned. Oh and sorry if I started this in the wrong forum my mistake.

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,555

Theoretical physicists have been trying for a long time to have a "Grand Unified" theory of the universe. Trying to understand how all the aspects of the universe such as gravity, electricity and atomic forces work together.

The latest theories require 11 dimensions to make them work! (I have heard of a theory needing 13 dimensions) And there are no experiments to prove or disprove them, so it is all just theory at the moment.

It used to be called "String Theory", but that has now been overtaken by "M Theory". If you want to read more, you might want to read about M-Theory

But who knows, someone may look at the equations they have worked on and think "hmmm ... if that is true, then maybe if I built this little gadget it should disappear here and pop out there".

There are still great mysteries to be uncovered and great discoveries to be made!

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