Cosmologic philosophy: new estimates say we are alone (Introduction)

by David Turell , Saturday, June 23, 2018, 17:59 (2345 days ago) @ David Turell

Using the Fermi paradox and the Drake equation, plus estimates of life's probability, new calculations say we are alone in the observable universe:

https://cosmosmagazine.com/space/stop-looking-for-et-modelling-suggests-we-re-alone-in-...

"The Fermi Paradox is named after physicist Enrico Fermi, who noted in 1950 that there are so many stars, just in the Milky Way, that given the age of the universe even a small probability that intelligent life has evolved would mean that their existence should be plain to humanity by now.

"Yet, he continued, in terms of evidence, we have squat, which, given the probability of intelligent life emerging, is odd. Hence the paradox. “Where are they?” he asked.

"The Drake Equation, formulated by American astronomer Frank Drake in 1961, attempts to place an analytical framework around Fermi’s contention, by estimating the number of intelligent civilisations that exist in the universe, regardless of the fact that we can’t see them.

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"Many outcomes from Drake Equation calculations yield probabilities that range over hundreds of orders of magnitude.

In a not altogether unrelated sidebar, the researchers acknowledge a recent calculation by Swedish-American cosmologist Max Tegmark, estimating the chances of intelligent civilisations arising in the universe.

"Tegmark assumes there is no reason two intelligent civilisations should be any particular distance from each other, and then argues that – given the Milky Way is a minuscule fraction of the observable universe, which is itself only a tiny part of the universe beyond what we can see – it is unlikely that two intelligent civilisations would arise in the same observable universe. Thus, to all intents and purposes, we are very probably alone.

***

"Sandberg, Drexler and Ord use a different approach in their modelling, incorporating current scientific uncertainties that produce values for different parts of the equation ranging over tens and hundreds of orders of magnitude. Some of these concern critical questions regarding the emergence of life from non-living material – a process known as abiogenesis – and the subsequent likelihoods of early RNA-like life evolving into more adaptive DNA-like life.

"Then there is the essential matter of that primitive DNA-like life undergoing the sort of evolutionary symbiotic development that occurred on Earth, when a relationship between two different types of simple organisms resulted in the complex “eukaryotic” cells that constitute every species on the planet more complicated than bacteria.

"The results are depressing enough to send a thousand science-fiction writers into catatonic shock. The Fermi Paradox, they find, dissolves.

“'When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations,” they conclude.

“'When we update this prior in light of the Fermi observation, we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe.

“'‘Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.'”

Comment: We certainly appear to b e alone in our local neighborhood.