I remember in my math class awhile ago there was a poster full of statistics like your chances of getting a royal flush on your first hand in a poker game.
Well anyway, it said that you have a 1 in 100 or 1000 chance in breathing a molecule of air once breathed by Napolean.
How is this possible?
I don’t know to what extent the molecule is separated during photosynthesis and respiration, but it is and interesting statistic.
I suppose that atoms inside the molecules could have been inhaled and exhaled by Napoleon, but I doubt that the entire molecule remained intact.
The facts, although interesting, are irrelevent.
sometimes when i am drinking water, i think to myself: ‘hey, some of this probably passed through a stegosaur’s intestine.’
what is essential is invisible to the eye -the fox
Air isn’t actually a molecule. It is a mixture of several different elements and compounts. We take in nitrogen, oxygen, CO2, water vapor, and argon. The only one on the list I would not see undergoing chemical changes is the argon. Argon is not a molecule, but an atom, but I will not read that much into the question.
Now, this would be the amount of argon Napoleon breathed during his lifetime dispersed throughout the planet. A person has his/her entire lifetime to take into their lungs one of those argon atoms taken into the lungs of Napoleon and then exhaled.
It sounds possible. Even more likely is an atom of any molecule taken in by Napoleon has been taken in by a significant number of humans today. I’ll stop at that.
Krish
I think the way the figured that was, calculating the number of air molecules, probably nitrogen molecules, someone breathed in their lifetime. Then they probably estimated how many unique molecules that would be, i.e., not counting those you breathed the second, third, or thousandth time.
Molecular nitrogen is fairly inert. I don’t know the half-life offhand, but only a small portion of molecular nitrogen gets fixed in a given year.
If they used oxygen molecules, all bets are off.
Matter is already created, it just gets recycled.
If you took all the matter of the earth & compressed it, you’d probably get something the size of a football so said my prof at UCSD.
You can say that every atom that makes up you was once a part of a star. At least that is what they told me back in sixth grade. The statement seems okay. Any objections?
This is exactly why I always use bottled water. 
Yer pal,
Satan
It’s all probability. You may want to take a laxative before you read further.
The assertion as I remember it was: If you take a deep breath, what are the chances you just inhaled a molecule that Julius Cesar exhaled in his dying breath? The surprising answer is better than 99%.
Assume that more than two thousand years the exhaled molecules are uniformly spread about the world and the vast majority are still free in the atmosphere. Apply straightforward probability: If there are N of air in the world and Cesar exhaled A of them, then the probability that any given molecule you inhale is from Cesar is 1-(A÷N). By the multiplication principle, if you inhale three molecules, the probability that one of them is from Cesar is (1-A÷N)³. Therefore, if you inhale X number of molecules, the probability becomes (1-A÷N)^X. Now, the probability f the complimentary event (your inhaling at least one of his exhaled molecules) is 1-(1-A÷N)^X.
A, X (each about 1/30th of a liter, or 2.2×10^22 molecules) and N (about 10^44 molecules) are such that the probability is more than .99.
Don Ho can sign autographs 3.4 times faster than Efrem Zimbalist Jr.
Methinks there’s a tiny error in opus’s calculation. A is the number of molecules ever breathed by Caesar, which should be order of 10^8 larger than the number of molecules in a single breath of air (X).
Though it does still come out to “better than 99% chance.” In fact, there’s about one in a hundred million chance that it does not contain any air inhaled by Caesar. There’s about (very roughly) 50% chance that every single breath you take in your lifetime contains at least one molecule inhaled by Caesar.
I wouldn’t say every single atom has been part of a star. There is some hydrogen from the Big Bang still floating around. But most other elements were created by fusion in stars.
I always find it more interesting to think that all iron and heavier metals were once part of a supernova. That’s the only way the can be created and released into space again.