3D - 2

What is the difference between 3D and 4D?

I have tried finding out but its over my head. Does anyone know a simple analogy to explain it?

Public Comments

1. The letters are the difference.
2. 4D is time. Here's a good one from Carl Sagan: http://www.youtube.com/watch?v=Y9KT4M7kiSw
3. 1 D
4. 4d is when you can : hear, smell , see and feel. 3d is something thats not flat (e.g. shapes )
5. Its D or -D Depends on 4D - 3D or 3D - 4D
6. that big building in Pairs - The Grande Arche http://en.wikipedia.org/wiki/Grande_Arche its an attempt to show a 4D cube. its not 4D because it is impossible to show 4D in a 3D world 1D = a line 2D = a square 3D = a cube 4D = !?!? the building has all the elements that define a 4D cube. double the edges, faces and points of a normal cube. i saw it on a Horizen episode with Allan Davies and some Oxbridge maths proffessor - watch it somehow!
7. it is very simple! 3D is three Dalmation and 4D is four Dalmation. when you draw or see something which seem you real is 3D.
8. Forget space for a second. Imagine a grid. Let's say you have information at point 5,6. That is a 2 dimensional array. You don't need to see the grid to know that it consists of 2 axis. Now imagine a 3d array. The co ordinates to a particular location might be 5,6,8. You can still imagine a 3d array being like a cube made of lots of smaller cubes. What happens in 4d? Now you need 4 sets of co ordinates to locate a particular piece of information. Eg 5,6,8,2. Now our brains can't comprehend a 4 dimensional shape because we exist in a 3d world... But you don't have to imagine what the shape would look like to be able to use this array. This works for 10d or however many dimensions you want. FYI arrays are used in programming.
9. the first three dimensions tell where in space a point is. The fourth, is time. That tells you when. Imagine having to catch a bus. You can plot it's position using the first three dimensions. But if you want to catch it at 9am, then that is it's position at that time. If you try to find it at ten minutes to, it won't be there. You need to know where and when it is at 9am to catch it. Or another example would be if you wanted to take a photograph of a plane. You need to know where and when it is to be able to take the picture. Longitude - 1st dimension, latitude - 2nd dimension, height - 3rd dimension and time - the 4th dimension. By the way, Carl Sagan just gave me a headache! Although the animated representative of a 4 dimensional cube below is cool, for god's sake don't read the description...
10. 1D, 2D and 3D all refer to spacial dimensions i.e., length, breadth and height. 4D refers to time, movement, or direction.