# Definition:Ordinary Space

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## Definition

**Ordinary space** (or just **space**) is a word used to mean **the universe we live in**.

The intuitive belief is that space is $3$-dimensional and therefore isomorphic to the real vector space $\R^3$.

Hence **ordinary space** is usually taken as an alternative term for Euclidean $3$-dimensional space.

## Also known as

**Ordinary space** can also be referred to as **physical space** but that term is also used in common parlance to mean a particular volume for day-to-day deployment of stuff.

*I would love to take my entire collection of cuddly toys on holiday with me to St. Petersburg, but I don't have the***physical space**in my suitcase.

In a wider sense, the term **natural world** can be used.

## Sources

- 1942: William H. McCrea:
*Analytical Geometry of Three Dimensions*: $\S 1$ - 1952: T. Ewan Faulkner:
*Projective Geometry*(2nd ed.) ... (previous) ... (next): $1.2$: The projective method - 1986: David Wells:
*Curious and Interesting Numbers*... (previous) ... (next): $3$ - 1997: David Wells:
*Curious and Interesting Numbers*(2nd ed.) ... (previous) ... (next): $3$