
How much air did Julius Caesar breathe in his lifetime?
Fact:
He was killed at the age of 56 (Et tu Brute?).
Fact:
On average, a human being uses between 1 and 2 m^{3} of air per hour.
A part of the exhaled air will be reinhaled, so let's say it is 1 m^{3}/hour.
Conclusion:
In a 56 year lifetime that is 56×365.25×24
= ca. 500000 m^{3}.
What fraction of the Earth's atmosphere is that?
Fact:
The Earth's circumference is 40000 km,
so its surface is 40000^{2}/pi = ca. 5×10^{8} km^{2}.
Fact:
The air pressure at ground level is 1 kg/cm^{2}
and the density of air at ground level is 1.225 kg/m^{3}.
Conclusion:
The air column above 1 cm^{2}
is 1/(1.225 kg/m^{3}) = ca. 0.82 m^{3} effectively,
and (0.82 m^{3})/(1 cm^{2}) = 8200 m,
so the effective thickness of the atmosphere is 8.2 km.
This leads to a total effective atmospheric volume
of 8.2×(5×10^{8})
= 4.1×10^{9} km^{3}
= 4.1×10^{18} m^{3}.
Thus, the fraction of the atmosphere breathed by Julius Caesar
is (5×10^{5})/(4.1×10^{18})
= 1.2×10^{13},
so about every 1.2 in 10,000,000,000,000 molecules of the Earth's atmosphere
have been inhaled and exhaled by Julius Caesar.
The Oxygen component of the air is an essential part of biological cycles,
but the 80% Nitrogen is chemically inert, so let's reduce this result
to 10^{13} = 1 in 10,000,000,000,000.
What does this mean?
Since the weather is a very turbulent global phenomenon (it takes only a week for a Caribbean hurricane to become a European depression),
all of Julius Caesar's exhaled air has been very homogeneously mixed with the atmosphere in the
(Julian) years that passed since he died.
Your own lungs contain ca. 3 to 4 litres of air right now,
let's calculate with 4 litres.
That is (using Avogadro's law: 6×10^{23} molecules
is ca. 25 litres at room temperature)
a total of 6×10^{23}×4/25
= ca. 10^{23} molecules.
Combining these results leads to the following conclusion:


Wherever you are on Earth, right now, at this very moment,
your own lungs contain 10,000,000,000 of the very same
molecules that were in/exhaled by Julius Caesar!
And now this:
Julius Caesar also has passed lots of water throughout his lifetime,
and to make a long story short:
say CHEERS to J.C. when you drink your next beer...

