we believe what we see

and here is a really good example a perpetual motion machine

and perpetual motion machines are inherently impossible.

They need energy to make the wheel go round and you cannot create energy out of nothing.

It has to have an energy supply.

But if you look at this wheel it is going round with no obvious way of propelling it

There's no motor. There all sorts of things around it but it's not clear how it works

and this perpetual motion machine belongs to me.

It was built by my friend David Jones who died last July 2017

and in his will he bequeathed me this machine.

He built it in 1980 or possibly 81 for an exhibition of the British Association.

This is a science festival that takes place every year

and it was displayed on the stand of the magazine New Scientist

and people were asked to guess how it worked. In all the years since then since 1981

only one person may have guessed the right answer and one of David's friends has got pretty close and

everybody else has got it wrong. So come and let me show you it a bit closer.

It's a bicycle wheel. A perfectly standard bicycle wheel

with three funny boxes on it

a copper stand something down here with heat sinks on it there are things that look as if there may be magnets round there

there's a box here labeled DREADCO. My friend David had a bogus company that he wrote about in his

funny column called Daedalus column in the journal New Scientist.

It stands for Daedalus Research

I'm not sure what E stands for

And Development Company.

It was completly bogus but quite often people tried to sue him

for patent infringement. I know because David was ill towards the end of his life

that this machine has been running for more than two years

without any attention

and it's a bit slower than it went before so presumably whatever it's mysterious energy source it's running down

But just before David died I persuaded him to write me a letter explaining, how the machine works

Here is the envelope

It's quite a funny envelope. It's a reused envelope from the UK tax authorities

but, you can see it says Sir Martyn Poliakoff and

it says here details of PMM one

perpetual motion machine one.

He built four of them. David was the only person in the world

who ever made and sold perpetual motion machines to people who knew they were fraudulent.

but they still bought them because they were fun.

They're only two people have read the letter, me and Neil.

and because i knew the secret would be safe with Neil

my guesses were completely wrong.

I thought i'd solved it one night lying in the bath.

I thought there was petrol in these cans which was some how being oxidized and acting as a jet engine

but was completely wrong

Brady: How did Neil react when he found out?

Neil is always inscrutable you can never tell what he's thinking

unless its when he's angry when I've made a mess and he's clearing it up.

So I think the answer is I don't know

But I know the secret is safe with him. It's much more interesting

to speculate about this than to know the answer

I felt a bit disappointed when I knew the answer.

I felt a bit cheated, oh it was that

But I hope you'll have fun thinking about it too.

You'll still see the flame going down then instead of going down in one great woosh

it jumps up and down the tube so it goes down a little bit and then up and down and up and down and so on...