Keswick AFC have a fantastic banner which reads "We only do positive". I think that's a great way to love but I was wondering where that leaves Physics. We have positive and negative charges. Positive and negative have meaning in vector fields. All gravitational potentials are negative. Maybe I should concentrate on scalar quantities like kinetic energy. The velocity, which as a vector can be positive or negative, is squared to make all values positive. Kinetic energy: we only do positive.
