[Note: this story was written for the New Scientist 2010 competition Forgotten Futures, which asked entrants to write a very short story -- 350 words or fewer -- about how things might have worked out if some scientific event or discovery had turned out differently. My entry wasn't shortlisted, so I'm sharing it here.]
Hugh Everett III eased himself into the oversized leather chair, taking care not to spill his cognac. Outside, he could hear the laughter of his children, grandchildren, and great-grandchildren, still loudly celebrating the 80th birthday of the Grand Old Man of Physics, as he had become known. The door opened quietly and his son Mark slipped inside, cradling the glass display case that held Hugh’s Nobel Prize medal. Mark reverently returned the medal, the centerpiece of the party, to its accustomed place on the bookcase.
Hugh gestured to the chair next to him where another glass of cognac waited, and Mark settled in next to his worlds-famous father.
“It’s ironic,” said Hugh, toasting the medal with his glass. “The press called me ‘the new Einstein’, and just like him, they gave me the Prize for my second-best work.” Few people outside the physics community realized that Everett’s Prize had been awarded for his audacious doctoral thesis that introduced the Many Worlds interpretation of quantum mechanics, not his later quantum gravity insights that had led to the exploitation of Dark Energy, the basis of the peace and prosperity enjoyed by everybody on Earth, not to mention it’s colonies on Mars and Ganymede.
“I’ll tell you what else is ironic,” replied Mark with a mischievous smile. “If everything possible happens in some universe, then somewhere out there is a world where everything went as wrong as it possibly could. Imagine if nobody had paid attention to your thesis and you had abandoned physics. In that world you became bitter and disillusioned, turned to cigarettes and drink, and died long before your time, leaving a world still suffocating and sweltering in its own pollution.”
Hugh laughed warmly. “Mark, that story gets worse every time you tell it. Many Worlds requires everything possible to happen, but it doesn’t allow for the impossible.” He took another sip of cognac and pushed away the thought of a life and a world gone to ruin. What ever might be might be, he mused to himself, but whatever must be must be.