Quiet and loud aliens

{{Short description|Concept in astrobiology}}

The concept of quiet and loud aliens is used in the modelling of hypotheses for the prevalence of extraterrestrial intelligence, particularly in the context of the Fermi Paradox. Hypothetical "loud" aliens expand their sphere of influence rapidly in a highly detectable way; hypothetical "quiet" aliens are hard or impossible to detect.{{Cite journal |last1=Hanson |first1=Robin |last2=Martin |first2=Daniel |last3=McCarter |first3=Calvin |last4=Paulson |first4=Jonathan |date=2021-12-01 |title=If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare |journal=The Astrophysical Journal |volume=922 |issue=2 |pages=182 |doi=10.3847/1538-4357/ac2369 |arxiv=2102.01522 |bibcode=2021ApJ...922..182H |issn=0004-637X|doi-access=free }} A special type of loud alien civilizations are "grabby aliens" who also inhibit the development of other technological civilizations in their sphere of influence.{{Cite web |last=Williams |first=Matt |date=2021-09-18 |title=If Aliens Are Out There, We'll Meet Them in a Few Hundred Million Years |url=https://www.universetoday.com/152508/if-aliens-are-out-there-well-meet-them-in-a-few-hundred-million-years/ |access-date=2022-12-07 |website=Universe Today |language=en-US}}