Wednesday, November 23, 2011

The Thermodynamic Meaning of Thanksgiving




How can thermodynamics have any bearing on a holiday of giving thanks for the bounty we enjoy? I will not bore you all with statistics of how many BTUs it took to raise the turkey, kill, clean, and freeze the turkey, or even roast the turkey. Rather this blog will remain philosophical (hence vague) and will tie in for you all how the third law of thermodynamics indeed explains the fundamental reason why we have Thanksgiving. Simply put the third law states that as temperature approaches absolute zero, entropy will approach a constant positive minimum, for perfect crystalline substances this constant minimum is zero. The three aspects of this law are Temperature, Zero, and Perfection.

These aspects are also the underlying principles of Thanksgiving. Thanksgiving is a late fall beginning of winter holiday. It is always celebrated on the fourth Thursday in November. Note not the last Thursday but the fourth Thursday. Thanksgiving and cold temperatures are synonymous. The zero aspect of Thanksgiving is not the quantity of food and drink consumed. This quantity is enormous and bordering on ridiculous. The zero aspect of Thanksgiving is the elimination of animosity between people and that differences become unnoticeable. The perfect crystal is found in the sugar in one of the pies that are eaten. For me it is Pecan Pie for others it is pumpkin pie.

Several years ago I wrote a blog about tryptophan. There is a myth that turkeys are loaded with this satisfying amino acid (sub unit of protein). Actually on a unit mass basis cheddar cheese has more tryptophan than turkey. For kids and adults who love grilled cheese one can have a far simpler and less expensive Thanksgiving meal and yet get the tryptophan trip. The news is filled that the price of turkey is at an all-time high and this is due to the high price of corn. Of course the price of corn is high because of bio-ethanol but I do not want to ruin your Thanksgiving by opining on the stupidity of bio-fuels. Instead I just want to wish you all a happy Thanksgiving. Enjoy the day that truly is as close to perfection as we get. For those nerds who want an explanation of the third law of thermodynamics I extracted this simple explanation from Wiki.

With the development of statistical mechanics, the third law of thermodynamics (like the other laws) changed from a fundamental law (justified by experiments) to a derived law (derived from even more basic laws). The basic law from which it is primarily derived is the statistical-mechanics definition of entropy for a large system:

S = kB log Ω

Where S is entropy, kB is the Boltzmann constant and Ω is the number of microstates consistent with the macroscopic configuration. In the case of a perfect crystal at zero degrees there is only one microstate and hence the log of 1 is 0 and the entropy is zero.

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