claim: Dark matter is hypothetical.
evidence: Dark matter is a hypothetical type of matter distinct from baryonic matter -LRB- ordinary matter such as protons and neutrons -RRB- , neutrinos and dark energy .. dark energy. dark energy. matter. matter. baryonic matter. Matter#Baryonic matter. neutrinos. Cosmic neutrino background. ordinary. Baryon#Baryonic matter. The existence of dark matter would explain a number of otherwise puzzling astronomical observations .. matter. matter. The name refers to the fact that it does not emit or interact with electromagnetic radiation , such as light , and is thus invisible to the entire electromagnetic spectrum .. electromagnetic radiation. electromagnetic radiation. electromagnetic spectrum. electromagnetic spectrum. Although dark matter has not been directly observed , its existence and properties are inferred from its gravitational effects such as the motions of visible matter , gravitational lensing , its influence on the universe 's large-scale structure , on galaxies , and its effects in the cosmic microwave background .. matter. matter. gravitational lensing. gravitational lensing. large-scale structure. Observable universe#Large-scale structure. cosmic microwave background. cosmic microwave background. The standard model of cosmology indicates that the total mass -- energy of the universe contains 4.9 % ordinary matter , 26.8 % dark matter and 68.3 % dark energy .. dark energy. dark energy. matter. matter. standard model of cosmology. Lambda-CDM model. ordinary. Baryon#Baryonic matter. mass. mass. Thus , dark matter constitutes 84.5 % Since dark energy , by convention , does not count as `` matter '' , this is 26.8  /  -LRB- 4.9 + 26.8 -RRB- = 0.845 of total mass , while dark energy plus dark matter constitute 95.1 % of total mass -- energy content .. dark energy. dark energy. matter. matter. mass. mass. The great majority of ordinary matter in the universe is also unseen , since visible stars and gas inside galaxies and clusters account for less than 10 % of the ordinary matter contribution to the mass-energy density of the universe .. matter. matter. ordinary. Baryon#Baryonic matter. mass. mass. The most widely accepted hypothesis on the form for dark matter is that it is composed of weakly interacting massive particles -LRB- WIMPs -RRB- that interact only through gravity and the weak force .. matter. matter. weakly interacting massive particles. weakly interacting massive particles. weak force. weak interaction. The dark matter hypothesis plays a central role in current modeling of cosmic structure formation and galaxy formation and evolution and on explanations of the anisotropies observed in the cosmic microwave background -LRB- CMB -RRB- .. matter. matter. cosmic microwave background. cosmic microwave background. structure formation. structure formation. galaxy formation and evolution. galaxy formation and evolution. anisotropies. anisotropy. All these lines of evidence suggest that galaxies , galaxy clusters , and the universe as a whole contain far more matter than that which is observable via electromagnetic signals .. matter. matter. Many experiments to detect proposed dark matter particles through non-gravitational means are under way ; however , no dark matter particle has been conclusively identified .. matter. matter. Although the existence of dark matter is generally accepted by most of the astronomical community , a minority of astronomers , motivated by the lack of conclusive identification of dark matter , argue for various modifications of the standard laws of general relativity , such as. matter. matter. general relativity. general relativity. MOND , TeVeS , and conformal gravity that attempt to account for the observations without invoking additional matter .. matter. matter. MOND. Modified Newtonian dynamics. TeVeS. Tensor–vector–scalar gravity. conformal gravity. conformal gravity