The damage was done

The damage was done.

The damage was done, there was no going back, the arrow of time only runs in one direction and entropy will increase until the inevitable heat death of the universe. If you don’t believe this, try removing all the honey you just stirred into your morning bowl of porridge or check with Brian Cox.

The question had been asked and it stood there in the room like a grey pachyderm with a leg at each corner slowly coiling and uncoiling its prehensile nose. It could not be ignored and demanded answers.

‘Why are there black gaps between the stars, Dad?’

Son was kneeling on the cushioned window seat looking up at the stars blinking like light shining through holes in the dark satin sheet of the night sky.

            ‘It’s because some stars are so faint we cannot see them and others are so far away we cannot see them either’ answered Dad.

            ‘How far away are they?’

            ‘Many light years’

‘What’s a light year?’

‘It’s a very long distance’

‘Longer than the road to Granny’s house?’

‘Yes’

            ‘Why can’t we see the ones that are a long way away?’

            ‘Because there is a limit to how faint a star can be before we cannot see it’

            ‘Whats a limit?’

‘It’s like a fence, it lets you go so far and no further’

            ‘Why?’ said Son.

Dad pretended an exasperated sigh as he tossed his latest copy of “Embalmer’s Weekly” carelessly onto the floor and gave his full attention to Son. He knew all about the Three Wise Men but still had problems dealing with a ten “whys” 8 year old.

            ‘I think the best thing is that I tell you the full story’, said Dad. ‘Come over here and sit on the sofa next to me and I’ll explain it all’

Son knew this was the prelude to one of Dad’s “I know everything and look how clever I am” sagas but the truth was that Son liked these evenings on the sofa with his hero Dad’s arm around him, he felt safe and loved.

Mum was in the next room, struggling with her latest TMA which would cut off  in 2 days.

            ‘A long time ago, a man called Barney wanted to move a rock but it was too heavy. He then found that if he poked the end of a branch under one corner and put a small rock under the branch, he could easily lift the rock off the ground. Barney had invented a first order lever. He still could not move the rock, however so he found a bigger branch and got his mate Rocky to put the big branch under the rock while he lifted it with his lever. They could now push it along but is was a hard, slow job because the rock was big and heavy.

He went down the trail to see his neighbour Dobbin, who had been trying to make bigger, stronger horses by selectively breeding them, and asked if he could borrow two of his biggest, latest specimens.

‘Neigh problem’ said Dobbin, ‘I’ll bring them up to you. So they tied the horses to the rock, levered it up, placed branches under and off they rolled. Problem! How to steer it? They cut the rollers short and put them around the outside. They had invented wheels and were really on a roll now.

Next problem was that the trail was very narrow so they had to have the horses as close together as possible and the rollers, which by now had developed into proper wheels were set at the same width – which turned out to be 4 foot 8.5 inches. This width can still be seen in the grooves cut by chariot wheels in Pompey.

‘When were there chariots in Portsmouth, Dad?’ asked Son

‘I spelt it wrong Son,’ said Dad, ‘it should have been Pompeii’

‘This gauge width has been adopted through history, for cart tracks and eventually railways – apar from the Reckless Engineer of course. This limits the width of loads that can be carried on railways so the main mirror for the Hubble telescope had to be designed down to this size. The light gathering potential of a telescope is limited by the surface area of its mirror and so limits how far away stars can be seen.’

            ‘So you see Son, it is the genius of Barney and Dobbin all those years ago that decided how far away we can see stars in the universe’ ’said Dad triumphantly, as he turned to look down at his sleeping Son.