What IS true 1D (or 1-dimensional)?

[Hatchet90]

I recently saw this video on College Humor and it got me thinking. There's a little flame war going on in the comments and I was just wondering, what IS the first dimension. I always thought that 1d meant 1 single axis, usually called the x axis. Then 2d had 2 axes, usually called the x and y axes. Then 3d had 3 axes, usually called the x, y, and z axes. But is this correct thinking?

 

[isometry]

I recently saw this video on College Humor and it got me thinking. There's a little flame war going on in the comments and I was just wondering, what IS the first dimension. I always thought that 1d meant 1 single axis, usually called the x axis. Then 2d had 2 axes, usually called the x and y axes. Then 3d had 3 axes, usually called the x, y, and z axes. But is this correct thinking?

Yes, your understanding is mathematically correct. The video was entertaining, it reminded me of the book flatland, which explores what life would be like in 2D:

http://en.wikipedia.org/wiki/Flatland

In mathematics there are several ways to define the dimension of a space. The definition you gave is one of them, basically the number of coordinates necessary to specify any location (e.g. in 3D you need three coordinates x,y,z). The surface of the earth is 2D so we can specify any point with two coordinates, longitude and latitude. If we include points above and below the surface of the earth then it's a 3D space so we need another coordinate, altitude.