# Time as a Dimension

1. Jun 16, 2009

### karkas

Since when is Time considered to be a dimension?

Is it after Einstein's G.T.R. or was it considered to be one before it?

2. Jun 16, 2009

### A.T.

People have used diagrams with time as a dimension long before Einstein/Minkowski. For example in order to visualize movement with a static diagram. There is nothing special about considering a physical quantity to be a dimension. But in GR it proves very useful.

3. Jun 16, 2009

### fleem

The concept of "dimension" and "vector" is just a way for us to keep from mixing different units and also to more easily define any transforms of conserved quantities that there might be between those dimensions, if any. For example, in a Euclidean space, transforms preserve distance. Also, one can imagine spaces in which the transforms are different depending on the particular dimensions involved.

Last edited: Jun 16, 2009
4. Jun 18, 2009

### brachid

Well ... first of all .. what is "dimension"? Whenever you use time or any other physical quantity as the component of some vector (including space components), is it enough to consider it as a dimension ?