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Barrel Expansion and Contraction is a Myth... Kinda (Part 1)

High School Physics Textbook
We have all heard the marketing.  Barrels and in many ways the Rickhouse are necessary for proper aging because of the ways that barrels expand and contract.  Without that you're not really aging the whiskey.  Its accepted as truth throughout the  bourbon and whiskey world, and there are definite results that back it up.  Barrels aged where temperature swings are smaller "age" much slower than those  where temperature swings are large. There are thousands if not millions of examples to back it up.  Well, what if all or part of that belief, held like a John 3:16 of the whiskey world, is false.

Lets take a brief detour to the wine world.  Wines that sell for thousands of dollars, new, come from some of the most prestigious vineyards in the old world.  That's thousands of dollars for 4 servings of alcohol.  Most of these top tier producers have expansive underground caves that were built hundreds of years ago where their wine is aged in barrels for roughly 2 years.  The flavors are different, but the aging process imparts the same changes to the liquid inside of the barrels as to the whiskey inside of barrels in a rickhouse in Kentucky.  The thing is that these caves essentially see zero temperature change, ever.  Where is the expansion  and contraction in the wine world?  Are these incredible wines  with hundreds if not thousands more years of tradition that whiskey not actually aging  in their barrels?  I think not.

So, if the expansion and contraction due to temperature swings isn't the magic that makes "aging" happen, how is the spirit going into and out of the wood?  I'll save  the bulk  of what was explained for part 2, but my high school physics teacher explained it all to me fairly quickly. (...and was fairly disappointed that I forgot the core basics of what he taught... maybe I was too busy playing  Ti-86 Tetris...)
You probably saw a diagram just like this in textbooks going as far back as elementary school.  It shows how liquid molecules behave.  Essentially they bounce around, filling any space they can, in near perpetual motion.  These liquid molecules don't freeze in place once they enter the wood of a barrel, they keep moving, and eventually work  their way deeper into the barrel, and eventually out of the barrel and back into the general body of liquid inside the barrel.  All of this takes place without any notable changes in temperature or pressure  swings.  ...Unless you get to absolute zero at –459.67°F, in which case all molecular motion stops.

Now, its obviously proven that things "age" faster when there are temperature swings in barrels, so the temperature swings obviously cause some difference.  If anything, these temperature swings can accelerate the rate at which the liquid molecules move into and out of the barrel, but that definitely isn't what is causing the "aging" to take place, it's merely changing the rate at which it happens. 

The acceleration in the "aging" caused by temperature swings is summed up  perfectly in the first law of thermodynamics.  Basically, as heat increases in a volume that is fixed, molecular motion aka pressure increases.  But again, this only accelerates the "aging" process.
Conclusion: The "aging" takes place in barrels with or without the temperature swings / expansion and contraction of the barrel. 
Now, Part 2 is going to get into some real controversy.  But for now, keep this in the back of your head since it will be key for Part 2:  The pressure the liquid molecules exert on each other (and on each wood molecule of the barrel) through basic molecular motion is both perfectly equal among all of the liquid molecules and perfectly omnidirectional on average.  

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