Inertia is a great thing. It keeps us rolling down the motorway when we let go of the gas pedal. It makes sure that big ships are not capsized by every little wave. It literally keeps the world turning. Now, Michael Faraday proposed that there was such a thing as mental inertia (his writing on this appears in ‘Life of Faraday’, pages 236–244). This means that when you are at rest, it’s difficult to get going (like trying to get a lorry moving). However, it also means that when you are already active it’s easier to keep going and you become almost unstoppable (like a moving lorry). These thoughts on the concept of mental inertia are all the more interesting as Faraday was a prolific scientist himself.
Getting into the bathtub is like entering the Dirac sea.
Now, when my daughter sits at the table and is drawing lots of beautiful things and it is time for her to take a bath, does she want to go? Well, she’s already drawing, so it’ll require some good motivation to make her go into the bath. What can make this unstoppable lorry change its course? I have found a trick to use here. It involves a little chewy vitamin that the kids can eat every day. They like the flavour and it is healthy too. When it is time to get the kids into the bath, I place the chewy vitamin on the edge of the bathtub just out of their reach. The only way for them to get it is to get into the bath. Then, I call them and say that there is this tasty vitamin chewy waiting for them. This then gives them the motivation to get into the bath as fast as possible so that they can grab and eat that vitamin. As it turns out, even unstoppable lorries like a tasty sweet.