3 ms·

I think they missed a great title opportunity. A "fart detector that works a mile away" seems to be great way to phrase it; it's concise, easy to imagine, relat

I think they missed a great title opportunity. A "fart detector that works a mile away" seems to be great way to phrase it; it's concise, easy to imagine, relatable and comical. The article could then go into the specifics of what the detector actually picks up (e.g. CH4). I find the diffusion of the smell of flatulence to be a better comparison, because it invokes a visceral reaction ("eww", "yuck", etc.). Imagining a device which does this seems easier. I have a worse idea of what "1/4 of a human exhalation" means.

gsaga 9y ago
And the comment of the year award goes to...
evrydayhustling 9y ago
Unfortunately for the fart detector (but fortunately for us!), human farts average around 100ml [1], whereas an adult male breath averages about 500ml [2]. That could still be sorted out for your title, but we also have to consider that a fart is only about 7% methane [3]. This suggests the one mile sensitivity is going to be at around 18 simultaneous average farts, or 5 at the record-breaking end of the scale -- conditions which might indeed justify further surveying the region at altitude. If we're willing to get closer than a mile (questionable in the above scenario), we can apply an inverse law for gas diffusion [4] (I was surprised it wasn't inverse square!) and find that the apparatus can can detect a single average fart at a distance of around 30 feet -- easily covering most elementary school classrooms and automating away the "whom smelt it dealt it" dilemma. [1] https://www.chemistryworld.com/news/explainer-the-chemistry-of-farts/2500168.article https://www.chemistryworld.com/news/explainer-the-chemistry-... [2] https://en.wikipedia.org/wiki/Tidal_volume https://en.wikipedia.org/wiki/Tidal_volume [3] https://en.wikipedia.org/wiki/Flatulence https://en.wikipedia.org/wiki/Flatulence [4] https://physics.stackexchange.com/questions/290059/inverse-square-law-equivalent-for-concentration https://physics.stackexchange.com/questions/290059/inverse-s...
ggambetta 9y ago
Sounds like a real-life version of Futurama's Smelloscope?
kragen 9y ago
Methane doesn't smell of flatulence; that smell consists of much larger molecules, which diffuse correspondingly much more slowly, and whose distribution is therefore more affected by advection.

gsaga 9y ago

And the comment of the year award goes to...

evrydayhustling 9y ago

Unfortunately for the fart detector (but fortunately for us!), human farts average around 100ml [1], whereas an adult male breath averages about 500ml [2]. That could still be sorted out for your title, but we also have to consider that a fart is only about 7% methane [3]. This suggests the one mile sensitivity is going to be at around 18 simultaneous average farts, or 5 at the record-breaking end of the scale -- conditions which might indeed justify further surveying the region at altitude. If we're willing to get closer than a mile (questionable in the above scenario), we can apply an inverse law for gas diffusion [4] (I was surprised it wasn't inverse square!) and find that the apparatus can can detect a single average fart at a distance of around 30 feet -- easily covering most elementary school classrooms and automating away the "whom smelt it dealt it" dilemma. [1] https://www.chemistryworld.com/news/explainer-the-chemistry-of-farts/2500168.article https://www.chemistryworld.com/news/explainer-the-chemistry-... [2] https://en.wikipedia.org/wiki/Tidal_volume https://en.wikipedia.org/wiki/Tidal_volume [3] https://en.wikipedia.org/wiki/Flatulence https://en.wikipedia.org/wiki/Flatulence [4] https://physics.stackexchange.com/questions/290059/inverse-square-law-equivalent-for-concentration https://physics.stackexchange.com/questions/290059/inverse-s...

ggambetta 9y ago

Sounds like a real-life version of Futurama's Smelloscope?

kragen 9y ago

Methane doesn't smell of flatulence; that smell consists of much larger molecules, which diffuse correspondingly much more slowly, and whose distribution is therefore more affected by advection.