Great Filter
The Great Filter, in the context of the Fermi paradox, is whatever prevents "dead matter" from giving rise, in time, to "expanding lasting life". The concept originates in Robin Hanson's argument tha...
Fermi paradox
The Fermi paradox (or Fermi's paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity's lack of contact with, or...
Fermi paradox - Wikipedia
Stellar engine
Stellar engines are a class of hypothetical megastructures which use a star's radiation to create usable energy. Some variants use this energy to produce thrust, and thus accelerate a star, and anythi...
Dyson sphere
A Dyson sphere is a hypothetical megastructure that completely encompasses a star and hence captures most or all of its power output. It was first described by Freeman Dyson. Dyson speculated that suc...
Dyson sphere - Wikipedia
Doomsday argument
The Doomsday argument (DA) is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far. Simply...
Doomsday argument - Wikipedia
Matrioshka brain
A matrioshka brain is a hypothetical megastructure proposed by Robert Bradbury, based on the Dyson sphere, of immense computational capacity. It is an example of a Class B stellar engine, employing th...
Project Ozma
Project Ozma was a pioneering SETI experiment started in 1960 by Cornell University astronomer Frank Drake, at the National Radio Astronomy Observatory at Green Bank, West Virginia. The object of the ...
Project Cyclops
Project Cyclops was a 1971 NASA project that investigated how SETI should be conducted. As a NASA product the report is in the public domain. The project team created a design for coordinating large...
Project Cyclops - Wikipedia
Sentience quotient
The sentience quotient concept was introduced by Robert A. Freitas Jr. in the late 1970s. It defines sentience as the relationship between the information processing rate (bit/s) of each individual pr...
Kardashev scale
The Kardashev scale is a method of measuring a civilization's level of technological advancement, based on the amount of energy a civilization is able to utilize. The scale has three designated catego...
Technological singularity
The technological singularity is the hypothesis that accelerating progress in technologies will cause a runaway effect wherein artificial intelligence will exceed human intellectual capacity and contr...
Relativity of simultaneity
In physics, the relativity of simultaneity is the concept that distant simultaneity – whether two spatially separated events occur at the same time – is not absolute, but depends on the obse...
Relativity of simultaneity - Wikipedia
Bracewell probe
A Bracewell probe is a hypothetical concept for an autonomous interstellar space probe dispatched for the express purpose of communication with one or more alien civilizations. It was proposed by Rona...
Project Orion (nuclear propulsion)
Project Orion was a study of a spacecraft intended to be directly propelled by a series of explosions of atomic bombs behind the craft (nuclear pulse propulsion). Early versions of this vehicle were p...
Project Orion (nuclear propulsion) - Wikipedia
SERENDIP
SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations) is a Search for Extra-Terrestrial Intelligence (SETI) program originated at the University of Calif...
Project Phoenix (SETI)
Project Phoenix was a SETI project: in this case a search for extraterrestrial intelligence by analyzing patterns in radio signals. It was run by the independently funded SETI Institute of Mountain Vi...
SETI
The search for extraterrestrial intelligence (SETI) is the collective name for a number of activities undertaken to search for intelligent extraterrestrial life. SETI projects use scientific methods i...
SETI - Wikipedia
Drake equation
The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The equation was written in 1961 by Frank D...
Drake equation - Wikipedia
Von Neumann probe
The idea of self-replicating spacecraft has been applied — in theory — to several distinct "tasks". The particular variant of this idea applied to the idea of space exploration is known as a von Neuma...
Allen Telescope Array
The Allen Telescope Array (ATA), formerly known as the One Hectare Telescope (1hT) is a radio telescope array dedicated to astronomical observations and a simultaneous Search for Extraterrestrial Inte...
Allen Telescope Array - Wikipedia
Project Longshot
Project Longshot was a conceptual design for an interstellar spacecraft, an unmanned probe, intended to fly to and enter orbit around Alpha Centauri B powered by nuclear pulse propulsion.
Develope...
Project Longshot - Wikipedia
Project Daedalus
Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible unmanned interstellar spacecraft. Intended mainly as a scientific probe, the de...
Project Daedalus - Wikipedia
Alderson disk
An Alderson disk (named after Dan Alderson, its originator) is a hypothetical artificial astronomical megastructure, like Niven's Ringworld, or a Dyson sphere. The disk is a giant platter with a thic...
Alderson disk - Wikipedia