The Nature of Dark Matter
Can
dark matter be composed of normal matter?
If so, then its mass would mostly come from protons and neutrons = baryons
The density of baryons right after the big bang leaves a unique imprint in the abundances of deuterium and lithium.
Density of baryonic matter is only ~ 4 % of critical density, total is 30%.
Most
dark matter must be non-baryonic!
