For this reason, this newspaper has a role in letting the public know about science. I have previously tried to help by writing about gravity and how we are wasting it by flying members of the government to weddings interstate and overseas.

Today, I take up my responsibility again, this time to write about molecules.

We are all made of molecules, some of which have funny names like bastardane and cadaverine and Buckminsterfullerene. They are the submicroscopic things - even tinier than Mirabella's experience in submarines - that all matter is made up of, or that make up all matter, if you don't like sentences ending with a preposition.

Many years ago, the Irish novelist Flann O'Brien, writing in the days when policemen rode bicycles up and down the lanes of his native country, noticed how the bicycle saddle gradually took on the shiny shape of the thing that was normally placed upon it.

He proposed this was because molecules were transferred from the human to the saddle, filling out those areas where there was not perfect contact. He suggested, moreover, that the transfer also went the other way - molecules migrate from the saddle to the rear end of the rider, thus explaining the odd walk of people when they first get off their bike.

The effect is not as noticeable these days, what with modern, computer-designed saddles, but it still occurs, the effect showing itself, for example, in the cranky and generally constipated disposition of cyclists who want to send motorists to jail for driving too close to them.

In the same way, have you ever noticed how people who ride horses develop a big derriere? This is because each time they sit in the saddle, molecules of the seat go through their jodhpurs, or whatever it is they are wearing, and are absorbed into their rear end.

The phenomenon is called ''gluteal osmotic migration'' or GOM. Professional jockeys stand in the saddle in an effort to cut down the GOM effect.

Another example of this molecular transfer is provided by the trucks that go around collecting our garbage each week.

Some people think they drive on the wrong side of the road just to annoy other traffic or so the driver can get a better look through people's front windows.

In fact, there is a much less sinister and more environmentally friendly reason.

When cars travel on the left-hand side of the road, molecules of rubber come off the tyres and stick to the road surface.

With thousands of cars dropping 10-to-the-power-of-some-number of molecules, all with their axes of symmetry and magnetic poles pointing in the same direction, the road soon develops a rubber coating.

The idea of driving the garbage trucks in the opposite direction, against these axes, is so the tyres on the truck can pick up some of the molecules - it's like rubbing velvet the wrong way. By doing this, they build up their thread, while at the same time removing rubber from the streets and making them safer.

In case they pick up too much thread, thus causing the tyre to become so fat that it rubs on the mudguard, the trucks all meet somewhere at the end of their round and we get the familiar sight of empty trucks racing each other back to the depot - more or less on the correct side of the road, on this occasion.

By the way, if you don't understand the axis of symmetry bit, ask your teenager. You may, of course, be lucky enough not to have one of your own, in which case you're bound to find some hanging out at the local shopping centre.

Teenagers study these things on the days when they're at school instead of at the shopping centre. The mere mention of the words ''axis of symmetry'' will either put them to sleep or start them off on a non-stop ''he-said-she-said'' monologue about their social life. With some teenagers, it will induce talking in tongues. It's an interesting phenomenon, and I will come back to it some other time.

You could ask teenagers about molecules, too, while you are at it. They are likely to be more coherent in this case, but it is doubtful they will tell you about the role played by these particles in the effects raised in this article.

Perhaps if we had a minister for science, he - Mr Abbott's ministers have to be male - would be able to get my theories taught in schools.

Anyway, that's what I think.

Frank O'Shea is a Canberra writer.