Do aliens exist? And should we try to connect? | BBC Ideas

Summary

The video explores whether intelligent extraterrestrial life exists and whether humanity should try to contact it. The vastness of the Universe makes it seem unlikely to some scientists that Earth is the only place with life. But Enrico Fermi’s question remains: If other civilisations exist, where is everybody?

Two approaches are discussed:

• SETI (Search for Extra-Terrestrial Intelligence): Scientists such as astrophysicist Mike Garrett listen for unusual radio signals. Natural radio emissions from stars, planets, and galaxies tend to be smooth, while artificial signals may have distinctive patterns because they carry information.
• METI (Messaging Extra-Terrestrial Intelligence): Douglas Vakoch argues that humanity should send deliberate messages rather than only listen, on the grounds that someone has to make the first move.

Arguments and challenges

• Potential risks: Stephen Hawking warned that broadcasting could have harmful consequences, drawing an analogy with the disastrous effects of European colonisation on Native Americans. METI advocates counter that Earth has already been leaking radio and television signals into space for decades, so an advanced civilisation might already detect us.
• The Zoo Hypothesis: Aliens might know Earth exists but observe us without making contact, as humans observe animals in a zoo. Vakoch suggests that sending messages could show that humanity is intelligent and wishes to communicate.
• Who speaks for Earth? Garrett argues that messages sent by individuals or groups may not represent humanity as a whole, raising questions about who has the authority to transmit them.
• Communication and distance: Contact would involve more than translating language: alien life could be fundamentally different, and the immense distances mean long delays. A message sent 1,000 light-years away would take 1,000 years to arrive, with a reply taking roughly another 1,000 years if the recipient’s technology were comparable.
• The Arecibo Message: The first message sent into space for the benefit of extraterrestrials was transmitted in 1974. No reply has been received so far.
• Searching for potentially habitable worlds: METI plans to target planets in the Goldilocks Zone, where conditions may be neither too hot nor too cold for life. SETI continues to improve methods for detecting signals.

The video concludes that detecting another civilisation could help people recognise both the differences between civilisations and the similarities they share.

Researchers and sources featured

• Mike Garrett — astrophysicist and SETI member
• Douglas Vakoch — founder of METI
• Stephen Hawking — cosmologist, cited for his warning about transmitting signals
• Enrico Fermi — physicist, associated with the question “Where is everybody?”