When searching for signs of extraterrestial life, exactly what are looking for?
In: Biology
Anything that’s not natural, or what we consider to be natural. On earth for example, an alien might see straight line structures and conclude they’re a sign of intelligent life (straight, symmetrical structures are very rare in nature).
In space we’re focusing on energy emissions, especially radio waves, and their patterns.
A burst of radiation that occurs once or twice every few years? Probably natural. One that appears precisely every two hours, follows a pattern, and originates from the same place? Might be worth investigating.
Our theory is that a space-faring species will have developed technology to either broadcast their presence through the galaxy, or significantly alter their environment at a planetary scale in a way that we could observe, whether directly or indirectly.
We also look for signs of chemicals in the atmospheres of other planets that we know are critical to life on Earth, or we believe are only produced through biological processes. This is what got everyone excited about Venus last week- phosphine gas. The scientists that discovered it in Venus’ atmosphere believe only a living thing could produce it.
mostly radio signals. The idea is that any advanced civilization will almost certainly at some point start using radio to transmit data. And while radio signals are made naturally, artificial ones will show complex repeating patterns that you don’t see in nature.
Since they travel at the speed of light in all directions, they’re a good thing to search for.
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