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We May Be All Alone In the Known Universe, a New Oxford Study Suggests (fortune.com)
A new study by Oxford University's Future of Humanity Institute determined that it's quite likely humans are alone in the observable universe. Fortune reports: The study looked at the Fermi paradox -- the apparent discrepancy between the seeming likelihood of alien life, given the billions of stars similar to our sun, and the scant evidence that such life actually exists. The paradox was named after physicist Enrico Fermi, who famously asked his colleagues at Los Alamos, N.M.. "Where Is Everyone?"
The study authors then examined various hypotheses and equations used to resolve the Fermi paradox. The results weren't pretty: "Our main result is to show that proper treatment of scientific uncertainties dissolves the Fermi paradox by showing that it is not at all unlikely ex ante for us to be alone in the Milky Way, or in the observable universe. Our second result is to show that, taking account of observational bounds on the prevalence of other civilizations, our updated probabilities suggest that there is a substantial probability that we are alone." SpaceX CEO Elon Musk cited the study's conclusions as an "added impetus" for humanity to become a spacefaring civilization capable of extending life beyond Earth. He tweeted: "This is why we must preserve the light of consciousness by becoming a spacefaring civilization & extending life to other planets..."
The study authors then examined various hypotheses and equations used to resolve the Fermi paradox. The results weren't pretty: "Our main result is to show that proper treatment of scientific uncertainties dissolves the Fermi paradox by showing that it is not at all unlikely ex ante for us to be alone in the Milky Way, or in the observable universe. Our second result is to show that, taking account of observational bounds on the prevalence of other civilizations, our updated probabilities suggest that there is a substantial probability that we are alone." SpaceX CEO Elon Musk cited the study's conclusions as an "added impetus" for humanity to become a spacefaring civilization capable of extending life beyond Earth. He tweeted: "This is why we must preserve the light of consciousness by becoming a spacefaring civilization & extending life to other planets..."
I'm going to be pedantic here and point out that there's a difference between the Fermi paradox and the Drake equation, I think you're referring to the latter. Fermi simply asked the question - if the universe is so big and so old, where is everyone else? Frank Drake came up with the equation and the variables to which you're referring, and Carl Sagan popularised it by estimating these probabilities quite optimistically high.
One thing I know, and that is that I am ignorant...
Simple answer to the paradox is that space is just too big. Technology to visit other stars may not be possible, or be sufficiently rare that expansion can go undetected.
The Fermi Paradox is an utterly useless test. It takes variables you have no data on and then says to compute their probability.
There are not variables in the Fermi Paradox, otherwise it would not be a paradox but an equation or a function. I do not know why you mentioned an equation, but probably it is because you do not know what we are talking about.
Note: I find it particularly annoying that random guys on the internet think they are masters of the known universe and _every time_ there is a discussion, you have to read caustic, trenchant comments using words like "utterly useless", "drunk frat students", "easily published paper out to boo[t] their careers". Discussions are rational processes, not political calls to arms, where you have to convey simple concepts to masses of mindless commoners.
The Fermi Paradox is an utterly useless test. It takes variables you have no data on and then says to compute their probability.
You mean the Drake equation, not the Fermi Paradox, and you're wrong about its usefulness, as you'd know if you bothered to read the paper. The authors make a very convincing statistical argument that the Drake equation actually resolves the Fermi Paradox.
Statistical probability, to be of any use in the real world at all, must by definition be based off already measurable data.
True
That we have basically no measurement of any of this data
False. As the paper points out, we can estimate the distribution of many of the astrophysical numbers with relatively low uncertainty -- a few orders of magnitude. And while the others are much more difficult, when we don't know how to estimate a parameter, it is often feasible to bound the parameter and estimate the degree of uncertainty. In this case, the authors construct plausible estimates for the uncertainty of the really difficult parameters. The uncertainties are enormous precisely because we know so little. For example, they estimate that our best estimate of f_l ranges over 200 orders of magnitude. They note that this is a conservative estimate, that the actual uncertainty may be much larger, but that larger uncertainties merely strengthen their result.
The authors assume that the parameter values are uniformly distributed, calculate the resulting PDF of N and conclude that based on our best knowledge (which is very poor -- that's the whole point of the paper, to make sure the paucity of data is properly considered), there is a significant probability that we are alone in the galaxy, and in the observable universe. Their PDF also shows that there is a significant probability that we are not alone. In fact the probabilities of being alone and not being alone are close to equal.
Thus, the paper rigorously demonstrates that the Fermi Paradox is not paradoxical, precisely because we cannot estimate the parameters to Drake's equation. They show that because our knowledge is so poor, universes that are both empty and teeming with intelligent life fall well within the bounds of a careful, rational, and mathematical analysis based on our best knowledge.
In short, they rigorously demonstrated that your intuition about Drake's equation is correct, that our knowledge of the parameters is so weak that the resulting equation does not allow us to predict anything.
However, they also note that the amount of effort we've put into SETI provides us with actual data we can use to revise our estimates of the Drake Equation parameters, albeit only a little bit. They apply Bayes Theorem under a few different models to update their uncertainty estimates, and use the updated parameters to recalculate the probability that we're alone. This is a process that we can continue over time, updating the parameter PDFs based on observations (of various kind, not just SETI null results), gradually narrowing the uncertainty.
That a paper from Oxford uses it is, one would hope, a joke from a couple drunk frat students hoping to get an easily published paper out to boos their careers.
You should read the paper. It's actually quite carefully reasoned and interesting.
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