The burden of evidence is on the original claim if it is not widely accepted or reasonably obvious. The only evidence is a lack of evidence. There are document

The burden of evidence is on the original claim if it is not widely accepted or reasonably obvious. The only evidence is a lack of evidence. There are documented examples that surface on a rare basis. The fact something has a term has no impact on the frequency of the event. Unless you think that a Dyson Sphere is something that's been observed.