Extraterrestrial intelligence

Extraterrestrial intelligence (ETI) refers to beings that might live beyond our planet and have the ability to think and solve problems like humans do. These beings could be living creatures from space or even advanced machines. So far, no one has ever found real proof that such life exists.

People have wondered if other worlds could be filled with life since very old times. When scientists learned that Earth is just one planet orbiting the Sun, and that other planets and moons exist, it became natural to ask if any of those places might also have life. This idea is now one of the most exciting and guesswork-filled questions in science.

ETI is also sometimes called "Extraterrestrial Technological Instantiations" to stay clear and simple. This name was created so we don’t have to use words like "civilizations", "species", or "intelligence", which might not always fit well.

Many scientists look for signs of advanced space technology, called technosignatures, to find if there are other clever beings out there. This search is a big part of science fiction stories and popular culture too.

Intelligence

Intelligence is a word we use to talk about life from space that might think and learn like humans do. Another word for this is sophoncy, meaning very wise or smarter, which was created by Karen Anderson and used in stories by her husband Poul Anderson.

Sometimes people use words like sentience or consciousness when they mean intelligence, but these words can also talk about life that isn’t smart or aware like humans. When we talk about an extraterrestrial civilization, we mean a group of smart, thinking life from space that might develop over a long time.

Probability

The idea that humans are not special observers of the universe leads many scientists to think that intelligent life must exist somewhere else in space. Famous scientist Stephen Hawking believed the vast size of the universe makes it likely that other smart beings are out there. But Fermi's Paradox asks why we haven't met or seen any of these other civilizations, even though we think they might be common.

Right now, we have not found any extraterrestrial life, smart or otherwise. Some ideas, like the Kardashev scale, try to guess how advanced a group of beings might be based on how much energy they can use. The Drake equation is another way to guess how many smart, communicating civilizations might exist in our Milky Way galaxy. One study in 2020 thought there might be about 36 such groups, very far apart from each other.

Search for extraterrestrial intelligence

Main article: Search for extraterrestrial intelligence

People have been looking for signals from intelligent life from other places in space for many years, but haven't found any clear signs yet. Some projects try to send messages out into space, hoping that intelligent life might receive them. These messages are often sent using radio waves, and sometimes even physical items like special plaques are used.

There are also efforts to understand how we might talk to other smart civilizations if they exist. One famous example is a message sent in 1974. Many groups and people around the world are working on these questions. Experts believe it is very unlikely we will make contact with smart life from space because the distances are so great. Sometimes, people think we might find signals from smart machines instead of living beings.

There was a famous radio signal called the Wow! signal, but it has never been seen again, so it is hard to know what caused it. In June 2022, scientists using a special telescope in China thought they might have found signals from outer space, but later found out these signals were probably caused by things here on Earth.

Potential cultural impact of extraterrestrial contact

Main article: Potential cultural impact of extraterrestrial contact

If humans ever met beings from space, the changes could be huge or small, depending on how smart and friendly those beings are. Some ideas suggest these beings might not even be alive in the way we are, but could live inside super-advanced computers. How we meet them—through signals, direct meetings, or strange objects—could also change what happens next.

People often compare meeting space beings to when different groups of humans first met on Earth, like during the Columbian Exchange. These meetings sometimes led to big problems for the group that was contacted. So, some worry that meeting space beings could also cause big changes for us. But since this hasn’t happened yet, these ideas are just guesses.

UFOlogy

The extraterrestrial hypothesis is the idea that some UFOs might be from space, carried by beings from other worlds, often called aliens. This idea is different from another thought called EDI, or extradimensional intelligence. In 2023, lawmakers in the United States House of Representatives had a meeting to talk about how the government deals with reports about UFOs.

In culture

The idea of intelligent life from space has been popular in stories and culture, especially since we started flying into space. In 2003, the state of New Mexico made February 14th "Extraterrestrial Culture Day."