What is the speed of smell? How far can smell spread? This is prompted by a bizarre dream I had. There we were when an alien space ship landed nearby, and then there was an overpowering acrid smell. The smell spread around the world extremely quickly. How could it spread so fast? Was it a weapon or instrument of the aliens? Were we going to die from whatever made the smell?
The speed of light is 186,282 miles per second. The speed of sound is 761.2 miles per hour. If it was going the speed of light it would only take 0.13 seconds to go around the earth. We wouldn't have time to ask the question if smell travelled as fast as light.
In comparison to light and sound there isn't a set speed to smell - the speed of smell is dependent on the odorous compounds that make up the air - we would ask how fast does air travel in the air?
Here is the article on the science behind the speed of smell. Let's jump to the fun comparison:
"So then, let's use Graham's Law to compare the effusion rates of two odorous molecules, geraniol and skatole. Gerianol has a rose-like fragrance that is commonly used in perfumes, and it's naturally found in geraniums and lemons. Skatole is a somewhat toxic compound that occurs naturally in feces, and it's thought to be one of the main causes of odor in flatulence. Yes, in one of the most high-brow and intellectual thought experiments ever devised, I'm basically asking which odor, under ideal conditions, you would smell first: a rose or a fart?
Gerianol is composed of ten carbon atoms, eighteen hydrogen atoms, and a single oxygen atom, which gives it a molar mass of 154.25 grams per mole. (A mole is a unit equivalent to about 6*10^23 individual molecules). Skatole, one the other hand, has nine carbon atoms, nine hydrogen atoms, and one nitrogen atom, which adds up to a molar mass of 131.17 grams per mole. Graham's Law says that the rate of gerianol effusion divided by the rate of skatole effusion will equal the square root of the molar mass of skatole divided by the molar mass of gerianol. In other words...
This means that the rate of effusion of gerianol is about 92% that of the rate of effusion of skatole. In other words, the speed of smell of a fart is faster than the speed of smell of a rose. Admittedly, that's all one hell of a massive approximation, but that still seems like the sort of information that's just worth knowing"
Let's ask the question: how fast does a fart travel? And the answer is 10 feet per second, or 6.8 miles per hour. That's going to take a long time to get around the earth.
Maybe that dream came about from this picture I took a few years ago. I was putting images through that Watercolour Filter the other day, and this delightful abstract came out. Starry sky sort of theme.
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