Bitcoin and the Law of Conservation of EnergyIn physics, the definition of "energy" is "that which allows work to be done."
This means that money is energy, since it can be used to do work via payments to people. The energy in money can be thought of as "economic energy". Economists call economic energy "price" and measure it in terms of "euros" or "Kenyan shillings" and so on.
But, these units are abstract because their quantity changes over time. Physicists would prefer to use units such as joules or kilowatt-hours, which have a concrete basis in physical realities of mass (kg), length (m), and time (s).
http://www.coindesk.com/bitcoin-law-conservation-energy/
