Two months ago our astronomers detected in the atmosphere of our nearest planet, Venus, a molecule, phosphine, that on Earth is produced by microbes. So the question arose whether there is life on Venus. NASA is already planning an exploration launch for around 2030.
More interesting question is whether there is life, especially intelligent life, anywhere in the galaxy or the universe? After all the universe is unbelievable huge. With trillions of planets, we still might expect a few technological civilisations to have cropped up over a very long span of time. But have we overestimated the chance that extra terrestrial life, once it appears, evolves intelligence. My bet is that life is common, but intelligent life may be rare.
The universe may be teeming with simple cell life form, like bacteria, but a more complex life form – including intelligent life – is probably very rare. All animals, plants and fungi evolved from one ancestor, the first ever complex, or “eukaryotic”, cell. This common ancestor consisting of complex, membrane-bound cells with a central nucleus, had itself evolved from simple bacteria. But it has long been a mystery why this seems to have happened only once: bacteria, after all, have been around for billions of years. The jump from simple organisms to multicellular eukaryotic organisms may have been a complete fluke. It required two simple cells to bump into one another in a particular way, one absorbing the other – an event of mind-boggling improbability. Similarly unlikely, he thinks, is the development of culture and intelligence.
With at least 100 billion planets in our galaxy (the Milky Way), scientists have estimated that there might be at least 36 civilisations in our galaxy. They arrived at this figure by assuming that, given a planet hospitable to life, intelligent life typically appears after about 5 billion years, because that is how it played out here on Earth. Then they expressed this as a fraction of the length of time for which those hospitable conditions persist – roughly, the lifetime of the host star. They also assumed that once an intelligent civilisation arises, it lasts for at least 100 years.
Assuming that it is the case of 36 other civilisations in the Milky Way. In that case, the average distance between them works out to about 17,000 light years, which makes it unlikely we might have for back-and-forth communication. It would take 17,000 years for any signal to reach us. And even if we’re able to understand it, any signal we send back would take another 17,000 years – and then another 17,000 years for them to reply. If there are thinking things out there, we’re probably never going to make contact with them.
Merry Christmas and May your New Year Be much more better that this year of The Virus Pandemic.