Can you answer the following Fermi question: How many people worldwide are having sex right now this minute?

Asked by mattbrowne (31643) April 2nd, 2009

In physics, particularly in physics education, a Fermi problem, Fermi question, or Fermi estimate is an estimation problem designed to teach dimensional analysis, approximation, and the importance of clearly identifying one’s assumptions. Named for 20th century physicist Enrico Fermi, such problems typically involve making justified guesses about quantities that seem impossible to compute given limited available information. The classic Fermi problem, generally attributed to Fermi, is ‘How many piano tuners are there in Chicago?’ A typical solution to this problem would involve multiplying together a series of estimates that would yield the correct answer if the estimates were correct. For example, we might make the following assumptions:

1. There are approximately 5,000,000 people living in Chicago.
2. On average, there are two persons in each household in Chicago.
3. Roughly one household in twenty has a piano that is tuned regularly.
4. Pianos that are tuned regularly are tuned on average about once per year.
5. It takes a piano tuner about two hours to tune a piano, including travel time.
6. Each piano tuner works eight hours in a day, five days in a week, and 50 weeks in a year.

I also want to find out if this Fluther question will be accepted by the moderators. Are all words in my question acceptable? What about the protection of minors using Fluther? I’m not even sure about the minimum age. Are there minor Flutherites?

Observing members: 0 Composing members: 0

I highly doubt your question would be modded for language. If anything, your question would be modded because it is too complex and unanswerable. Then again, some questions that are unanswerable are still permitted due to them being “interesting” or likely to create an interesting debate. I’m not sure if this question fits that description, but I’m not a mod, so my opinion here doesn’t really matter too much.

Regarding minimum age, when signing up it says one must be 13 years or older to use the service. Of course, there’s nothing checking this for accuracy, nor is there a way to do so. There have been a few younger users, but the last one I knew of (90s_kid) left the site.

dynamicduo (14352)

This is certainly a better question for a 13-year-old than those about poop color, fart jokes, sexual positions and non-traditional sexual behavior.

Is a query about when to put the apostrophe in “its” considered a Fermi question?

gailcalled (54579)

DragonFace (570)

@gailcalled – You mean its versus it’s? This would be a grammar question.

mattbrowne (31643)

Wouldn’t the answer have to be ZERO? If they were, they couldn’t be typing in an answer here.

Mr_M (7596)

does this question include self service? We may have too many variables…

EVERYONE, except You! and me :(

Bagardbilla (4565)

Your questions are better than sex, matt. So I stopped, and came here to read your latest.

Zen (7748)

Matt,
Since it is a Fermi question: I’ll send my assumptions to you off line Like the 1.05 question you posted. However, I will show you my answer: 744,047.
I included the people that started and finished while I was reading the question and working on the solution.
That answer really bothers me. 750,000 and I’m not getting any now!

Lupin (4385)

@mattbrowne No, it’s a punctuation question, isn’t it?

gailcalled (54579)

I read xkcd this week, too. ;)

tonedef (3935)

your question reminded me of a scene in Amelie ,she asks the same question but I think she limits it to Paris.

lercio (768)

everybody but me, I assume

lazydaisy (1505)

@gailcalled – I’m not sure the apostrophe in “its” is considered punctuation like commas, periods and m-dashes. It certainly changes the word class.

mattbrowne (31643)

@Lupin – Thanks, I’ll check it out. Several months ago we had a similar discussion on wis.dm and a few came up with a solutions, but there many assumptions to be made. No self service, average activity per week, average duration of the activity, time of the day of the question and the population density of the related time zone.

mattbrowne (31643)

Hey! Am I the only other tech nerd out here? This is a Fermi question. We need to have at least one other person throw out an answer. @mattbrowne You’re up I guess.

Lupin (4385)

@Lupin – Here’s one answer: Let’s start with the average cycle of 24h – we need 8h of sleeps; 8h of work; and 8h to do all of the stuff we normally do (including sex). So with any given weekday (M-F) the odds of being in the “sex window” (lets call it 2h out of the 24) are 1/12 – the rest of the 11/12ths population are in sleep/work/other_stuff mode (this number could go up to say 6h out of the 24 or 25% on a weekend Sat/Sun). We now have to define sex: Is it two (or more) people who lust after each other in various states of undress and arousal (with or without the whipped cream & whips) or can we include those solo performances as well. For the purpose of this estimate, solo is just fine (“I know just how I like it”). Also, we will include solo humans who prefer their partners to be off genus. So we have a candidate pool of 550M on a weekday and a candidate pool of 1.65B on weekends. Now, out of this candidate pool we have to take out those people too old to have sex; those too young to have sex; those too tired to have sex; and those who say they have given up sex (either for the clergy or are practicing teen abstinence (are you kidding?). So we would “bell curve” the population and include 15y through 55y – lets call that a whopping 60% of the population which reduces our candidate pool to 330M (weekday) and 990M (weekend). Lets say, for arguments sake, not everyone in the pool has opportunity, monogamous couples might do it once a month, that some people are taking up the slack and doing it with multiple partners every night, etc. A sexual frequency of once a week doesn’t sound that off. So if we reduce the candidate pool to 1/7th. We get: 47M (weekday) 141M (weekend).

Makes sense?

mattbrowne (31643)

I came up with a smaller number. I answered the question “how many are having sex right now?” I believe your result answered the question “how many have sex today?” I included an average duration for the blissful event and then modified it a bit to add a time duration for reading the question.
I did not include solo flights. Now are we close?

Lupin (4385)

Don’t mention the duration assumption in public. We wouldn’t want to surprise the ladies.

Lupin (4385)

@Lupin – So how exactly did you end up with 744,047 ?

mattbrowne (31643)

@mattbrowne I’ll answer you off line so I don’t influence the outcome. Could it be we are the only two math nerds on this site?

Lupin (4385)

@Lupin – Thanks, got your PM!

mattbrowne (31643)

or