What are dimensions?

Answer 1

We humans view the world in three dimensions of space and one of time.

You could say that one dimension is width the second height, and the third is depth (the order of these is arbitrarily chosen). The fourth dimension of time is when an object appears at a specific location.

An object that is two dimensional is flat; it has no depth. An example is a piece of paper. A photograph or a map can be a two-dimensional representation of a three-dimensional world. So a shadow is a two dimensional projection onto a (flat) surface of a three dimensional object.

Some conjecture that time is the fourth dimension, while others call the fourth dimension "space-time" to reflect how space bends out of three dimensions when gravity gets involved. For an interesting discussion, read Steven Hawking's A Brief History of Time, which is probably available at your local library.

Other contributors have said:

• They are depth width and length of an object
• Some 'string' theories hold that there are 6 or 9 or 10 dimensions of space and one of time
• A dimension is a concept