If there is no "most accepted" explanation, then what would be the most scientifically probabilistic explanation to the Fermi paradox?

The Fermi paradox, named after Italian-American physicist Enrico Fermi, is the apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability (such as some optimistic estimates for the Drake equation)

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    $\begingroup$ There is none, it's all opinions based on the limited data, $\endgroup$
    – GdD
    Apr 21 '20 at 8:05
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    $\begingroup$ I believe, instead of closure as "opinionated", giving an answer explaining the comment above, would be the right thing to do. The keyword: popular science. $\endgroup$
    – peterh
    Apr 21 '20 at 8:33
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    $\begingroup$ @peterh-ReinstateMonica I agree that despite the fact that someone just posted an opinion-based answer, a good answer can be written and we shouldn't close this question. $\endgroup$
    – uhoh
    Apr 21 '20 at 11:42
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    $\begingroup$ @user30007 Have you checked his website? "Please note: Barry is not a Ph.D. and should not be referred to as "Dr." " setterfield.org/GSRbiography.html It sounds like he didn't finish his undergrad degree. $\endgroup$ Apr 22 '20 at 18:54
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    $\begingroup$ @OrganicMarble an untestable hypothesis jumps to a stable theory quickly it seems. $\endgroup$ Apr 24 '20 at 15:56

That's Not How Science Works

We don't need an explanation for the Fermi paradox, because we have no evidence that needs explaining. We have a sample size of exactly one when it comes to life in the universe, and we can't draw scientific conclusions from that.

Of course, scientists love to speculate like everyone else, so lots of them have opined on possible reasons why we haven't spotted other civilizations. But until we have actual hard data to work with, none of this is scientific.

That said, some explanations are more grounded in reality than others. For example, speculating that a galactic civilization might destroy anyone who becomes known is just pure science fiction. On the other hand, exoplanet surveys, studies of supernovae and gamma-ray bursts may help us constrain some aspects of the issue and rule out certain reasons.

But as of now, there just isn't enough data to have 'scientific' theories, let alone have enough of them for one or more to be leading candidates. It's all just speculation and thought exercises now, and there's not even enough information to know which ones are better than others.

If you were to ask most scientists informally, I think you'd find that most of them suspect that life is common, based on the speed at which it appeared on Earth after it was capable of sustaining life, but that complex life may be very rare, given that it took billions of years to develop on Earth after single-celled life arrived. They might also apply the Copernican principle that the Earth is not special, so we should expect to find life elsewhere.

But again, with a sample size of one that can only be speculation.

  • $\begingroup$ Well, science works by proposing hypotheses and testing them. The Drake equation can be viewed as a hypothesis and the Fermi paradox can be viewed as the results of the first attempt to test it, so I think that this is precisely how science works! Considering that Enrico Fermi made significant contributions to the development of statistical mechanics, quantum theory, and nuclear and particle physics he probably knew something about how to apply the scientific method. $\endgroup$
    – uhoh
    Apr 23 '20 at 21:33
  • $\begingroup$ Formulating the question is science. Astronomy used to narrow down terms in the Drake Equation is science. but speculating as to the reason for the Fermi paradox is not, since we simply don't have any evidence favouring one reason over another. Nothing wrong with brainstorming possible reasons, and that brainstorming may even inform lines of scientific research, but we just don't have the data to draw any conclusions, or even to have favored hypotheses. $\endgroup$
    – Dan Hanson
    Apr 23 '20 at 21:38
  • $\begingroup$ okay +1 because I see your point I think, but I feel that this paradox does indeed need explaining. While perhaps we can not at the moment evaluate those explanations sufficiently, we can use the nature of and differences between those explanations to possibly guide the design of future experiments; better instruments for optical, radio or other observations just as an example. $\endgroup$
    – uhoh
    Apr 23 '20 at 21:43
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    $\begingroup$ Sure! It's also great fun to think about. But the OP was looking for a 'most accepted' explanation by scientists. My point was that there can't be one, because we can't draw scientific conclusions without data. Maybe I'm being a little too picky, but it's an important distinction. And it's subject to change. For example, if Kepler had not found a single exoplanet, we'd probably have a scientific consensus that the most likely reason for the Fermi Paradox is that planets are rare. But every time we look we fail to find anything unique about Earth, so we just don't know. $\endgroup$
    – Dan Hanson
    Apr 23 '20 at 21:55
  • $\begingroup$ okay I think I've got it now. No I see what you mean and you are not being too picky. thanks for your help! $\endgroup$
    – uhoh
    Apr 23 '20 at 22:03

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