About: http://webisa.webdatacommons.org/341291155

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	Another reason could be that the tubes could be evacuated of all interstellar dust, gas, and other debris which such ultrarelativistic craft could otherwise run into and be destroyed in an instant.
http://www.w3.org/ns/prov#wasQuotedFrom	centauri-dreams.org