Hall Effects (IMAGE) Foundational Questions Institute, FQXi Caption The Hall effect can come in classical or quantum forms. The quantum version is an emergent property of vast numbers of electrons, which underlies the bizarre condensed-matter phenomena seen in many topological materials, such as topological insulators. Credit Created by Elfy Chiang for the Foundational Questions Institute, FQXi. © FQXi Usage Restrictions Free to use if correctly attributed. Credit: Created by Elfy Chiang for the Foundational Questions Institute, FQXi. © FQXi License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.