## Saturday, February 17, 2007

### Spreng's triangle

A fundamental question facing our civilization is: which direction do we wish to go on Spreng's triangle?

Let me explain. Daniel Spreng conceived the eponymous triangle illustrated here to demonstrate the inter-relationship between the energy, time, and information expended or used to complete economic tasks. Each point in the lattice represents a different combination of energy, time and information.

For example, the more information (knowledge, understanding) we have, the more efficiently we can achieve a task; i.e., we can achieve the same task by expending less energy. We can think of a particular task as being achieved in a certain time (in rough terms, at a certain speed), by expending a certain amount of energy, at a certain level of efficiency.

A task can be achieved quicker if either (i) the amount of energy expended is increased, whilst the efficiency with which it is expended remains constant, or if (ii) the amount of energy expended remains constant, but the efficiency with which it is expended is increased, (or if (iii) both energy and efficiency are increased). As a sweeping generalisation, the technological history of the 20th century is one in which tasks have generally been achieved quicker by the expenditure of more energy.

If we are about to suffer an energy crisis, either due to global warming, or due to the end of cheap oil and gas, then we may need to travel in a different direction on Spreng's triangle. To consume less energy in the completion of a task, one must either (i) achieve the task more slowly, or (ii) expend the energy more efficiently, (or both).

As an example of the interplay between energy, time and information, (which I mentioned on Bryan Appleyard's blog last year: www.bryanappleyard.com/blog/, and which has been emphasised by Autosport's Mark Hughes) motorcar manufacturers are steadily increasing the efficiency of the internal combustion engine. In motorsport, this increasing efficiency is used to make the cars go faster whilst expending the same amount of energy; in road-cars, this increasing efficiency is used to make the cars expend a smaller amount of energy whilst going at the same speed.

John Barrow has also written about Spreng's triangle in his book, 'Impossibility'. See p146-147 here: www.angelfire.com/indie/green_economics/Limits.pdf