TO BE, or not to be? The question that tormented Hamlet also seems to have been an obsession with Ettore Majorana, the celebrated Italian physicist who disappeared in mysterious circumstances in the 1930s. An analysis of his letters suggests that Majorana answered the question with his own unique quantum mechanical twist, managing to achieve the illusion of being both dead and alive at the same time.
Born 100 years ago this week, Majorana鈥檚 genius was likened to that of Newton and Galileo by Nobel laureate Enrico Fermi, his supervisor at the Institute of Physics in Rome. Majorana is today credited with predicting that neutrinos have mass 鈥� something that was only confirmed during the last decade. And more of his prescient theories are now coming to light (see 鈥淎head of his time鈥�), suggesting that Majorana鈥檚 achievements were underestimated when he was alive.
The young physicist鈥檚 promising career was cut short with his sudden disappearance at the age of 31 during a boat trip between Palermo and Naples in Italy. His body was never found despite several investigations, and opinion is divided on whether he committed suicide, was kidnapped, or changed his identity and started a new life.
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Now, theoretical physicist Oleg Zaslavskii at Karazin Kharkiv National University in Ukraine is suggesting that the ambiguity surrounding his fate was part of an elaborate illusion engineered by Majorana himself to demonstrate quantum superposition. This paradox, in which a particle can simultaneously exist in two mutually exclusive quantum states, is exemplified by Schr枚dinger鈥檚 cat, a thought experiment in which the cat can be both alive and dead.
Majorana wanted to mirror this paradox with events in his own life, says Zaslavskii (). The argument centres on a bizarre series of messages that Majorana sent to his family and to Antonio Carrelli, the head of the Institute of Physics at the University of Naples. First, Majorana sent a letter expressing his intention to commit suicide, which he followed with a telegram refuting the idea that he was suicidal. It was his third letter, however, that struck Zaslavskii as most odd. In it, Majorana describes his hope that Carrelli received both the original letter and the telegram at the same time.
鈥淎 sender should hope that the second message came first, to cancel the earlier one with the more disturbing content,鈥� says Zaslavskii. Instead, Majorana wanted two mutually exclusive outcomes 鈥� his suicide or survival 鈥� to co-exist, making it the 鈥渜uantum mechanical version of the Hamlet question鈥�, he says.
鈥淢ajorana wanted two mutually exclusive outcomes 鈥� his suicide or survival 鈥� to co-exist鈥�
When Zaslavskii analysed other events surrounding the disappearance he saw the same pattern. For instance, Majorana is thought to have hired impostors to pose as himself during the boat trip. 鈥淚 suddenly realised that all these separate and seemingly extravagant details are united by the same underlying idea,鈥� says Zaslavskii. 鈥淚t was very impressive.鈥�
鈥淶aslavskii has quite consistently shown how skilfully Majorana could have implemented his knowledge of quantum physics,鈥� says Gennady Gorelik, a science historian at Boston University. 鈥淗is theory resolves the strange and crazy behaviour of a great physicist and shows that it could have been logically organised.鈥�
But Majorana鈥檚 actual fate and motivations will probably remain a mystery. 鈥淚t鈥檚 very difficult for any historian to know what is going on in the mind of another figure,鈥� says Gorelik. 鈥淏ut perhaps it takes another theoretical physicist like Zaslavskii to be able to make the intuitive leap into Majorana鈥檚 mind.鈥�
Ahead of his time
Ettore Majorana often refused to publish his theories or speak in public about his ideas. Now, newly translated lecture notes show that Majorana may have anticipated Nobel laureate Richard Feynman鈥檚 work on quantum physics.
Just before he disappeared in 1938, Majorana handed a folder of notes accompanying a rare series of lectures to one of his students. Physicist Salvatore Esposito of the University of Naples, Italy, analysed the notes, and was surprised to see that Majorana had intuitively stumbled on an idea that was developed by Feynman in 1948: the so-called path integral formulation, which says that the state of a particle at any time is the sum of an infinite number of paths that it could have followed until then. 鈥淢ajorana was probably the first to conceive quantum mechanics according to the picture introduced later by Feynman,鈥� says Esposito (European Journal of Physics, vol 27, p 1147).
Majorana鈥檚 notes also contain attempts to connect this path integral formulation to Heisenberg鈥檚 uncertainty principle. 鈥淭his relationship has not yet been pointed out by anyone else,鈥� says Esposito.
