According to classical thermodynamics, with every breath that you take, there is approximately a 100% chance that you will inhale at least one air molecule that was exhaled by Julius Caesar in his dying breath. I just thought you might like to know. Please Register or Log in to view the hidden image!
And with each breath that we take we may also inhale air particles that someone let out thousands of years ago, from a body hole below the belt. On the serious note, where did you get that piece of information? Please provide a link and further ideas of the sort.
No link, this is a simple calculation. I ran across this classical factoid in college. If we consider the volume of air inhaled with each breath, about one liter I think, call this liter A, and then the number of molecules in that liter (A), and then if we distribute those molecules evenly throughout earth's atmosphere, we find that we have at least one of the original molecules from liter A, per liter [liter B] of atmosphere. One liter of air contains about 2.7 E22 molecules The mixing atmosphere is about 50 KM high; which yields a total mixing volume of about 6 E8 cubic miles. 2.7E22 / 6 E8--> ~4.5 E13 molecules from liter A per cu mile of atmosphere. This reduces to about 300 molecules per cu ft, and finally 10 molecules from liter A in liter B. So by this rough estimate, and after sufficiently mixing the air for about 2000 years, we expect to find about 10 molecules from liter A in any liter B. Edit: the first number was given as 2.7 E23 instead of E22, however the next calculation accounts for this.
Eh, that's just a cup-of-coffee-and-the-back-of-a-napkin problem. You should see what I can do with a pot of coffee and a few paper towels. Please Register or Log in to view the hidden image!
Okay <i>quoted from Ivan Seeking</i> <b>So by this rough estimate, and after sufficiently mixing the air for about 2000 years, we expect to find about 10 molecules from liter A in any liter B. </b> That's what I questioned.Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! Would the 10 molecs figure decrease or increase if the 'mixing' period were, say, 10 millenia (10000 years)?
That's just how long we must stir the pot before mixing is complete. After that, in principle it makes no difference; its mixed. In reality, eventually something will break down those molecules by reacting with them chemically. So eventually we start getting into trouble. I don't know how long this takes.
Broken down chemically..... Are you suggesting that the 10 molecs figure may fall into some new figure like 5 for a longer period?
No, I mean that the O2 and CO2 molecules will react and be split up such that the Oxygen and Carbon atoms will still be around, but they are no longer associated as a complete molecule. They go their separate ways to to speak. If we look more closely this get much more complicated. Note that I kept using the word "classical". This means that we can ignore some of the tremendous complications brought into this problem by Quantum Mechanics. That would go way beyond the scope of my napkin. Please Register or Log in to view the hidden image!
Well since you're typing it, it's beyond your napkin already, so.... Develop your idea as far as you can.
Here is the error in your computations How do you know that the air we breath distributes evenly throughout the earth? Don't you think that's an overly simplistic dumb assumption considering that density layers, temprature, wind, ect...all considered variable unknown parameters plays an important role in the air distribution across our atmosphere.
Well, this in an interesting fact from thermodynamics; not my idea by the way. I'm not inclined to write a paper on the subject. Please Register or Log in to view the hidden image!