::: A definition of ordinary matter is right there in the sentence that refers to ordinary matter (emphasis added): "According to the Planck mission team, and based on the standard model of cosmology, on a mass–energy equivalence basis, the observable universe contains 26.8% dark matter, 68.3% dark energy (for a total of 95.1%) and 4.9% ordinary matter." I'm not clear what more we need. It's possible that that sentence has too many qualifiers and thus this important one gets lost; for example, the "According to the Planck mission team" bit could go; that's a detail that can be left to the reference and the body of the article. I'll tweak the sentence to be more clear. —Alex ( |  |