Science does not always aim for exact numerical precision. So-called Fermi questions (questions that can be answered using Fermi's estimation technique) have been answered by science (not necessarily on SE) approximately, such as:

Many sciences rely heavily on Fermi questions. So do certain branches of biology.

Some Fermi questions can be easily answered due to public availability of all necessary information, but do require some expertise (for example knowledge of such information sources).

Are such questions welcome on Biology.SE? If not, which site guidelines say so?


Sure, Fermi questions are welcome.

It's Fermi answers we should all be cautious about. The way I see it, many laypeople tend to look for answers without considering or checking the method critically, so Fermi answers tend to be easy ways to spread misinformation.

It's important to explain the how one reaches the answer to a Fermi question. Without that transparency, Fermi answers are baseless, cannot be questioned, checked nor falsified, and often the answers do not highlight that they may be wildly incorrect approximation or based on invalid assertions or missing considerations. For example, when guessing how many planets there are in the universe, it is imperative to state the dubious assumption that each star on average has an n number of orbiting planets around it. If things are in the open, there is no problem. This of course does not mean anyone's guess is golden and the usual rules of science still apply. I don't think scientists see Fermi questions as a different kind of science or question about the natural world, anyway.

I personally recall recently answering some Fermi questions about glucose absorption in the mouth and about whether it is likely that daughter cells can inherit exactly zero mitochondria from the parent cell during cell division. Good questions.

  • $\begingroup$ Suggested edit: replacing "Fermi answers" by "(intransparent) answers to Fermi questions". $\endgroup$ – root Oct 16 '19 at 8:14
  • $\begingroup$ Indeed, transparency is crucial. The way a Fermi question is formulated can encourage transparent answers. $\endgroup$ – root Oct 16 '19 at 8:16
  • $\begingroup$ I'm accepting this answer because all discussion here (including comments of the other answer, now deleted by a moderator) identified guidelines that welcome such questions, and did not identify any guidelines that forbid such questions. $\endgroup$ – root Oct 16 '19 at 8:16

I looked up the definition of a Fermi question from the Wikipedia link you gave, and tried to think how the question "Approximately how many ribosomes are in a cell" would conform to such a definition. What are the rule of thumb approximations on which such a question would be answered? Presumably a knowledge the dry weight of a cell, the percentage of the dry weight of a cell that is RNA, the percentage of RNA that is rRNA and the molecular weight of rRNA.

I have two observations on this:

  1. I don't think this is interesting or important for modern biology.
  2. If the answer can be estimated in this way, why don’t you do it yourself, rather than expect someone on this list to do it for you? And in any case it’s unlikely that anyone would go around with their memory stuffed with such information.

I personally do not welcome this sort of question, which I refer to as a “Guiness Book of Records” question, and which I would vote to close on the basis of it being “dull and stupid” if I didn’t know that it would incur the displeasure of the moderators. It seems to me that sort of question asked by the bored for no other reason to be able to respond with a “fancy that!”. I don’t.

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    $\begingroup$ Ya'll were getting a bit chippy in the comments here and raising flags, hence the cleanup. Try to keep the comments focused to asking for clarification; you can show your agreement and disagreement on meta by voting up and down. If you have new meta questions you can ask a new question; if you have a different opinion on the topic asked in a question, you can post a new answer and let others show agreement and disagreement by voting. $\endgroup$ – Bryan Krause Mod Oct 16 '19 at 16:07

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