Consider the following. 1) Time runs slower downstairs than it does upstairs. 2) Time is affected by speed. Parents having been on a long, high-speed space journey might return to find themselves younger than their children. 3) At 90 per cent of the speed of light, a spacecraft is half its normal size. The bodies of the astronauts will also be squashed down to half their normal width - not that the astronauts would feel a thing. 4) If you know exactly where to find an electron, you can have no idea what it is doing; if you know what it is doing, you cannot know where it is doing it.

It’s no wonder people are inclined to dismiss such findings of relativity and quantum theory as defying common sense.

But be careful. Einstein once defined common sense as “that layer of prejudice laid down in the mind before the age of 18”.

I have long contended that our first introduction to the mind-blowing world of modern physics should be when we are young, when our minds are still open and flexible. As we get older, we become set in our thinking, our view of the world fossilised; we become resistant to new modes of thought.

But can eight to 12-year-olds absorb ideas traditionally regarded as difficult?

The American child psychologist Jerome Bruner thought so. “Any subject can be taught effectively in some intellectually honest form to a child at any stage of development,” he said. It is simply a matter of devising “a courteous translation”.

Naive optimism? Not really. At the Open University, before launching some innovatory type of teaching on our students, we developmentally test it on guinea pigs. That is the strategy I adopted when writing my introductions to modern physics for young people. Hundreds of children took part in the tests.

Did the children understand the physics? Not in the same way as a professional physicist does; that would have required mathematics. But they certainly appreciated what it was about: how relativistic and quantum processes affect things.

So that is the first reason for presenting modern physics to children: it is easier to be introduced to it as a child, than at a later age.

Second, it provides a way of motivating children to study physics in general. There is a growing concern over the relative unpopularity of physics as a course option. Physics is perceived as being hard and boring.

This is hardly surprising when you look at the national curriculum. At the time it was being drafted, I was vice-president of the Institute of Physics. The institute was asked for its views on the proposed topics. The education committee was dismayed and protested that, with a couple of minor exceptions, it could all have been written 100 years ago; it was as though nothing of interest had happened in physics this century.

But all to no avail. Such a lost opportunity. A survey of university physics undergraduates long ago revealed that it was an acquaintance with modern physics (gained casually rather than at school, presumably) that had fired their enthusiasm for the subject.

A boy once declared to me that he had read my introduction to quantum physics 87 times. I did not believe him. I told him he must be exaggerating; if it were true, he would by now know it off by heart. Whereupon he began to recite it word for word! Such is the power of quantum physics to excite the imagination.

A third reason for getting into modern physics early is that many of its pioneers, including Einstein, Heisenberg and de Broglie, were young (early twenties) when they made their discoveries; it was when their minds were still comparatively flexible. Who knows what further discoveries might be made by the physicists of the future if they can be introduced to the unresolved problems when they are really young - when they are children.

I once gave a talk on quantum physics to children at the Science Museum in London. A boy raised his hand. He reminded me how I had said in one of my books how matter collapses gravitationally down to a point at the centre of a black hole. “But now you’re saying that when things are small - like electrons - you need quantum theory to understand what’s going on.” I agreed.

Later I saw the boy being dragged out of the bookshop by his mother, his head already buried in his newly acquired book. He was searching it for what amounted to a quantum theory of gravity. He would be disappointed; that was a theory that eluded even Einstein.

Who knows, perhaps that boy will one day become the scientist destined to devise it. He at least has the advantage over Einstein that he has been thinking about it since the age of seven.

Russell Stannard, former professor of physics at the Open University, and author of the ‘Uncle Albert’ books, will present the Institute of Physics Lecture, ‘Stimulating interest in Physics’, at the ASE conference at Reading University on Saturday, January 9