Extraterrestrial intelligence

Extraterrestrial intelligence (ETI) means beings that might live far away from Earth and can think and solve problems like humans. These beings could be living things from space or very smart machines. No one has found real proof that they exist yet.

People have wondered if other worlds have life since ancient times. When scientists learned that Earth is just one planet around the Sun, and that other planets and moons exist, they started to ask if any of those places might also have life. This idea is now one of the most exciting questions in science.

ETI is also sometimes called "Extraterrestrial Technological Instantiations" to keep things simple. This name was made so we don’t have to use words like "civilizations", "species", or "intelligence", which might not always work well.

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

Intelligence

Intelligence means life from space that might think and learn like humans do. Another word for this is sophoncy, which means very wise or smarter. This word was made by Karen Anderson and used in stories by her husband Poul Anderson.

Sometimes people use words like sentience or consciousness when they mean intelligence. 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.

Probability

Many scientists think that because the universe is so big, intelligent life must exist somewhere else. Famous scientist Stephen Hawking believed this too. 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.

Search for extraterrestrial intelligence

Main article: Search for extraterrestrial intelligence

People have been looking for signals from smart life in space for many years, but haven’t found any clear signs yet. Some projects try to send messages into space, hoping smart life might receive them. These messages are often sent using radio waves, and sometimes 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.

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, life could change a lot or just a little. This would depend on how smart and friendly these beings are. Some ideas say these beings might not even be alive like we are, but could live inside very advanced computers. How we meet them—through signals, direct meetings, or strange objects—could also change what happens next.

People sometimes compare meeting space beings to when different groups of humans first met on Earth, like during the Columbian Exchange. These meetings sometimes caused big problems for the group that was contacted. So, some people 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. These beings are 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 talked about how the government handles reports about UFOs.

In culture

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