Money is energy, d$/dt is power.

I was thinking today about Star Trek, money, communism, and the phrase "money is power." In the future Trek universe, they supposedly don't use money. But they must use some unit of exchange to mediate the supply and demand for raw resources. And even in the Trek world, people clearly own things ranging from trombones to space ships. A Soviet-style centralized approach is probably mal-adaptive even in the future, so there must be some mode of exchange for goods services.

So I thought, what unit of exchange would these future people use? The answer seemed immediately obvious: Joules. Conservation of energy is the one universal limitation on wealth. Energy is literally a measure of work and is therefore closely tied to value. I'm sure economists have always been aware of this, but it seemed like a surprising realization to me. There must be some proportionality between real energy (in Joules) and the value of the dollar.

As an almost trivial example, I buy 11.25 kWh (40.5 MJ) of electrical energy for $1. I might there for say that a dollar is worth approximately 40.5MJ, which is really a hell of a lot of energy. Through mechanical labor alone, I would have to push a cart containing 100kg of stuff over 405km to earn a single damn dollar. At the other end of the spectrum, Bill Gates is currently worth about $29G, or 1.1745e+18 J. This is enough energy to shift the Moon's orbit by about 15um, which is quite a lot for a man whose own mass is 21 orders of magnitude smaller than that of the Moon.

Now on to the phrase "money is power." Actually, power is the rate of spending. Every dollar I spend per day is roughly 470W of power. The average human body consumes about 100W of power. The human brain, that mighty seat of the soul, knowledge and wisdom, consumes about 23W of power. Damn, do we use a lot of energy.

As an aside, the United States alone consumes over 22 million barrels of oil per day. There are 6.17MJ in a barrel of oil. There are about 300 million people in the US. That works out to an average of 452kJ of oil per person per day, which you might say is an average consumption of 5.3kW of oil per person. Dayum.