It is a well known fact that, in the eyes of a grandchild, grandfathers are the indisputable source of all knowledge. They know everything there is to know about everything. Grandmothers are the source of all yummy food and the great healers of tummy upsets and grazed knees.

So when my young grandson came to me with a question, it was reasonable for him to expect a definitive answer, me being the fountain of all wisdom. Imagine my dismay when I realised I did not have an answer. The reputations of all us most wise grandfathers was at stake. I did what any granddad would do in the circumstances. I told him it was bedtime and that I would answer his question tomorrow. A cop out, of course, but it has bought me some time. So all you most wise grandfathers out there, please come to my aid.

Here is the question: “If the Arabs are taking oil out of the ground at several thousand barrels a day, what is filling up the space left behind?”

My first reaction was to say “groundwater”. “But,” came the response, “water is ‘thin’ (his word). “Won’t the rocks above sink into the water?”

Get out of that one. “And if they sink is that why we have earthquakes?” Good point. Err. “And grandfather, you said that the centre of the earth is a fireball, like a big furnace. Won’t the water boil? And if it boils is that why we have volcanoes?”

Err. “And you said the oil in the car cools the engine so if we take it from the earth will the surface of the earth warm up? Is that why we have global warming?” Answer: “Is that the time already? Off to bed my boy. We will talk later.”

Please help me. The clock is ticking. My position in my grandson’s mind as an equal to Solomon, to Socrates, to Eratosthenes and to Pythagoras is seriously threatened. Thus, your wise advice will be greatly appreciated.