The great tallyboard in the sky

Driving anywhere in the centre of Sydney, one of the first things one sees when turning a corner is Centrepoint Tower. Yesterday was one of those days:

You know your youngest son ...

Who's that?

Ross ... your youngest son ... well he helped with Centrepoint.

I didn't know that. Why didn't I know that?

Well, Dad, I only found this out when he was down for your birthday and the conversation turned to hot-rivetting just like ours did down under the bridge a few minutes ago. You remember Ross is a metallurgist, right?

They don't hot rivet any more. What did Rossie do?

He worked out the tensile strength required of the struts that hold the tower up.

(pause)

I didn't know that. Why didn't I know that? (pause) Is that an achievement?

Yes, Dad. That is an achievement.

(pause)

Have you achieved anything?