The common definition of matter is anything that has both mass and volume (occupies space).[45][46] For example, a car would be said to be made of matter, as it occupies space, and has mass.
The observation that matter occupies space goes back to antiquity. However, an explanation for why matter occupies space is recent, and is argued to be a result of the Pauli exclusion principle.[47][48] Two particular examples where the exclusion principle clearly relates matter to the occupation of space are white dwarf stars and neutron stars, discussed further below.
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