About: http://webisa.webdatacommons.org/339570502

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Is it not the case that only a ???massless??? particle can have two helicity states(=spin directions?) + and ??? along its traveling direction such as a photon or gluon?
http://www.w3.org/ns/prov#wasQuotedFrom	profmattstrassler.com