<http://webisa.webdatacommons.org/prov/92745003> <http://www.w3.org/ns/prov#wasDerivedFrom> <http://webisa.webdatacommons.org/3574849> . <http://webisa.webdatacommons.org/3574849> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/prov#Entity> . <http://webisa.webdatacommons.org/3574849> <http://www.w3.org/ns/prov#value> "Is there such a thing as a Black Hole or is the center of the galaxy something else like heavy-matter that creates a hub of a wheel that all ordinary matter spins around through its gravitational vortex?" . <http://webisa.webdatacommons.org/3574849> <http://www.w3.org/ns/prov#wasQuotedFrom> <harvard.edu> .