<Ul> <Li> Quintessence </Li> <Li> Phantom energy </Li> </Ul> <Li> Dark matter <Ul> <Li> Cold dark matter </Li> <Li> Warm dark matter </Li> <Li> Hot dark matter </Li> </Ul> </Li> <Ul> <Li> Cold dark matter </Li> <Li> Warm dark matter </Li> <Li> Hot dark matter </Li> </Ul> <Li> Cold dark matter </Li>

When did we learn there were other galaxies