Showing posts with label Wald. Show all posts
Showing posts with label Wald. Show all posts

Monday 29 September 2014

The One That Got Away


Abraham Wald, was a gentle kind-hearted man with a genius that was breathtaking.  He was born in Hungary in 1902 and was the son of a Jewish baker.  Fascinated with equations he studied hard and became a graduate student at the University of Vienna.  His mentor was the great mathematician Karl Menger.  Karl Menger had attended the Döblinger Gymnasium in Vienna where two of his fellow students were Wolfgang Pauli (Nobel Prize for Chemistry in 1938 ) and Richard Kuhn (Nobel Prize for Physics in 1945).  It is perverse that in just one city during a short period of time so many great minds began their careers.

Menger would pose problems to the young Wald, problems that stumped great minds across academia.  Wald would spend time reflecting on his given task and invariably return within a month with a solution to the problem and an urgent request for another to solve.  His hunger for problems and ability to solve them became known to mathematicians in the US.  When the Nazi threat grew this mathematical prodigy was able to flee, albeit reluctantly, to the US from Vienna.  It was a timely move.  His entire family of nine members, bar one single brother, died in the extermination camp Auschwitz.

Wald was put to work in the US on the Applied Mathematics Panel.  This group was posed questions by the military and they would use their mathematical ability to answer the query.  For example, the navy was trying to shoot torpedoes against Japanese vessels  The panel was able to work out the speed of the ship from the distance between the crests of waves.  They then had to factor in some adjustments to take into account the turning motion of the ship but once they had the equations their predictions matched real life experience and proved invaluable in targeting ships.  At times what appeared real life observations could be the thing that gives you a totally wrong answer. 



The World War 2 bombing crews would limp back home peppered by bullet holes.  So high were the losses, the military examined the planes that returned to see what particular areas on the plane needed reinforced with steel plates.  It would be impossible to reinforce the entire plane as they could not fly with such weight.  After careful investigation they noticed that the bullet holes were found mostly along the wings, down the centre of the body and in the tail.  The military wanted to put the armour on the areas where holes appeared to be clustered.  Wald with his usual insightful genius stated that putting the armour there would be of no benefit at all.  He had instantly recognised that the holes showed where a bomber could be shot and still make it home.  The armour should be put on the areas where there were no bullet holes, the engine, stabilisers etc.  Any bullet hitting those would never have made it home.  He could see the survivor bias that was derailing the statistical analysis the military was so proud of.

This quiet likeable genius was an inspired problem solver.  It was his passion and his talent.  Wald published papers on geometry which were described, by his mentor Menger, as:-


... deep, beautiful and of fundamental importance.

He was an excellent teacher who was renown for being

“ a master at deriving complicated results in amazingly simple ways”.

He died in his late forties while on a lecture tour in India in a plane crash.  Having saved so many who flew, with his mathematical genius, it is strangely disturbing that it was a plane that ended his life.