> [!infobox] <s class="aside-in"><em>mentioned in 4 topics</em></s> #### <s class="topic-title">[[dark matter]]</s> > [!wikipedia] [dark matter](https://en.wikipedia.org/wiki/Dark%20matter) > > Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the [[universe]]. Various astrophysical observations — including gravitational effects that accepted theories of [[gravity]] cannot explain unless more matter is present than can be seen — imply dark matter's presence. > > Dark matter is called "dark" because it does not appear to interact with the [[electromagnetic field]], which means it does not absorb, reflect, or emit [[electromagnetic radiation]] (like light) and is, therefore, difficult to detect. > > The primary evidence for dark matter comes from calculations showing that many galaxies would fly apart, that they would not have formed, or that they would not move as they do if they did not contain a large amount of unseen matter. Other lines of evidence include observations in gravitational lensing and the cosmic microwave background, along with astronomical observations of the observable universe's current structure, the formation and evolution of galaxies, mass location during galactic collisions, and the motion of galaxies within galaxy clusters. In the standard Lambda-CDM model of [[cosmology]], the total mass-energy content of the universe contains 5% ordinary matter and energy, 27% dark matter, and 68% of a form of energy known as [[dark energy]]. Thus, dark matter constitutes 85% of the total mass/energy, while dark energy and dark matter constitute 95% of the total mass-energy content. Because no one has directly observed dark matter yet – assuming it exists – it must barely interact with ordinary [[baryonic matter]] and radiation except through [[gravity]]. > > Although the scientific community generally accepts dark matter's existence, some astrophysicists, intrigued by specific observations that are not well-explained by ordinary dark matter, argue for various modifications of the standard laws of [[general relativity]]. These include [[modified Newtonian dynamics]], [[tensor–vector–scalar gravity]], or [[entropic gravity]]. These models attempt to account for all observations without invoking supplemental non-baryonic matter. > ##### ^dataviews > [!dataview]+ Related unlinked notes > > No results to show for list query. > [!dataview]- Other unlinked mentions > > - [[Lambda-CDM model]] > - [[Standard Model]]