A man who went a very long way to prove a point

New Scientist press release

02 August 2006 The man who was both alive and dead under embargo until 02 Aug 2006 18:00 GMT

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’s 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 – something that was only confirmed during the last decade. And more of his prescient theories are now coming to light (see “Ahead of his time”, below), suggesting that Majorana’s achievements were underestimated when he was alive.

The young physicist’s 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.

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 Schrödinger’s 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 (www. arxiv.org/physics/0605001). 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.

“A sender should hope that the second message came first, to cancel the earlier one with the more disturbing content,” says Zaslavskii. Instead, Majorana wanted two mutually exclusive outcomes – his suicide or survival – to co-exist, making it the “quantum mechanical version of the Hamlet question”, he says. 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. “I suddenly realised that all these separate and seemingly extravagant details are united by the same underlying idea,” says Zaslavskii. “It was very impressive.”

“Zaslavskii has quite consistently shown how skilfully Majorana could have implemented his knowledge of quantum physics,” says Gennady Gorelik, a science historian at Boston University. “His theory resolves the strange and crazy behaviour of a great physicist and shows that it could have been logically organised.”

But Majorana’s actual fate and motivations will probably remain a mystery. “It’s very difficult for any historian to know what is going on in the mind of another figure,” says Gorelik. “But perhaps it takes another theoretical physicist like Zaslavskii to be able to make the intuitive leap into Majorana’s mind.”

Author: Zeeya Merali.