This article first appeared on the FQXi community website, which does for physics and cosmology what Plus does for maths: provide the public with a deeper understanding of known and future discoveries in these areas, and their potential implications for our worldview. FQXi are our partners in our Science fiction, science fact project, which asked you to nominate questions from the frontiers of physics you'd like to have answered. This article addresses the question "Are there parallel universes?". Click here to see other articles on the topic and here to listen to the accompanying podcast on the FQXi website.

He certainly had a beautiful mind. This exceptionally gifted Princeton mathematician made key insights in game theory, yet throughout his life, he was haunted by personal demons. But this isn't the story of John Nash, complete with Nobel Prize, best-selling biography and Oscar-winning movie. It's the story of the equally compelling Hugh Everett III, the man who proposed the many-worlds theory of quantum mechanics.

Peter Byrne

Everett is not being depicted by Russell Crowe in a big Hollywood movie (yet). But this physics genius is finally having his story told thanks to Peter Byrne, a California-based investigative reporter, with help from a $35,000 FQXi grant.

Byrne's normal beat is "corporate and government malfeasance," a far cry from quantum physics and parallel worlds. But, in 2000, his friend Stephen Shenker, a physicist at Stanford University in California, introduced Byrne to what he calls "weird physics." After writing several popular physics articles Byrne was looking for another good story. What better than the man who invented the theory of multiple universes?

The seasoned reporter tackled the story like any other investigative assignment. His first "informant" was a Russian physics textbook printer, Eugene Shikhovtsev, who had written an online biography of Everett. Byrne became enthralled with the anti-hero Everett, an alcoholic who suffered from depression, and died before seeing his idea — initially dismissed as nonsensical — gain the respect it deserved.

As Byrne investigated, a picture began to emerge of a deeply troubled individual with tremendous gifts.

Birth of an idea

Everett's early home life was highly dysfunctional. His military father and artistic mother divorced at a time when you still had to travel to Mexico to break the marital bond. Everett never really reconciled with his mother, who also suffered from depression, but he adored his father.

Academically, however, Everett always stood out. In his first year at grad school at Princeton, he hung out with many pioneering game theorists and wrote a paper that is still considered a classic in the discipline.

In his second year, he attracted the venerable John Wheeler, a fundamental contributor to the fields of quantum mechanics and general relativity, as his thesis supervisor. It was Everett's PhD thesis that contains his revolutionary and lasting many worlds theory.

Byrne discovered new materials about the theory when he met with Everett's only son, Mark, who fronts the band Eels. In his basement, Mark had kept boxes upon boxes of his dad's belongings and documents.

"The basement was a biographer's dream to find untouched materials of that nature," said Byrne. "I found the handwritten draft of the original thesis. I found three little papers about certain elements of his theory that shed some light on his real thinking. It actually reinvigorated a lot of the discussion about what Everett really meant."

Hugh Everett in 1964 Image: Mark Everett

Everett was looking into the fundamental puzzle of measurement in quantum mechanics. In the 1920s, some of the founding fathers of quantum theory met in Copenhagen and decided upon what has become its standard interpretation: before observation, quantum objects don't exist in a single state, but are described by a wavefunction containing a superposition of multiple states, exemplified by Schrödinger's cat in a box that is both alive and dead at the same time. When a measurement is made, however, the wavefunction "collapses" and the quantum object snaps into one set state (see this Plus article for more information).

But Everett wasn't content with this picture. In essence, he wondered why a wavefunction should collapse just because an observer interacts with it. He argued that you don't need collapse if the observer becomes entangled with the superpositioned object. Instead, due to the correlation between the observer and the object, the observer splits into multiple copies. Each quantum option is satisfied — the cat both lives and dies — just in two parallel worlds.

Wheeler was impressed and presented the idea to quantum heavyweight Niels Bohr, who was largely responsible for the Copenhagen interpretation. But Bohr dismissed it. As a result, the thesis was cut by almost three quarters and reformulated to minimise disagreement with Bohr. When it was published in 1957, it didn't generate much immediate response.

Saving the world(s)

Bohr's rejection displeased Everett, but he had not planned to stay in academia. Before his thesis was published, he took a job with a Pentagon think-tank that studied how to fight nuclear wars. There he discovered that radioactive fallout would be much worse than anyone had previously imagined. He also worked on optimising the "cost-benefit" of both offensive nuclear weapons and defensive systems. And he wrote much of the original software for the first Single Integrated Operating Program, the ultra-secret hydrogen bomb targeting list.

"Everett himself would have been Dr. Strangelove," says Byrne. "He was the quintessential cold war technocrat. Here's this guy who is actually designing multiple scenarios for World War Three that believes that there are multiple universes where his designs are being implemented. Yet he did it anyway."

But while Everett was building a career for himself far away from esoteric questions about parallel worlds, his earlier work was gaining an underground following. One of the former students of Wheeler that Byrne spoke to was Wojciech Zurek, now at the Los Alamos National Laboratory, who explained that Everett gave a generation of physicists the permission to look at the universe quantum mechanically. This stood in stark contrast to Bohr's interpretation, which said that you can only talk about the universe in classical terms.

In the 1960s and 70s, Bryce DeWitt, a theoretical physicist and acting editor for the journal Reviews of modern physics, which published Everett's thesis, championed Everett's idea. Although DeWitt wasn't originally convinced by the outlandish idea, Everett's sharp wit won him over. When DeWitt wrote to Everett saying that he "could not feel himself split," Everett retorted that critics of Copernicus also said they could not feel themselves moving through the heavens.

Meanwhile, Everett and some colleagues had formed a private company that ran classified computational problems for the Pentagon. But, after several years, the business went under and Everett ended up working on relatively uninteresting computational problems just to make a living.

From left to right: Charles W. Misner, Hale F. Trotter, Niels Bohr, Hugh Everett, David Harrison. Image: Eugene Shikhovtsev

Personally, Everett was also struggling. An alcoholic, he drank three martini lunches and womanised in the work place and beyond. He ate raw hamburger and smoked three packs of cigarettes a day. More importantly, he was totally disconnected from his family. He was surprised, despite numerous warning signs, when his teenage daughter tried to commit suicide just one month before Everett himself died of a massive heart attack in 1982 at just 51 years of age.

Sadly, Everett didn't live to see his work gain the great following amongst physicists and cosmologists that it now commands. Several prominent quantum computer scientists believe that the power of quantum computers comes from the ability for superpositioned elements to compute complex problems in other universes and reassemble an answer in this universe. In 2007, the 50th anniversary of Everett's theory was celebrated on the cover of the journal Nature.

Of course, the theory remains controversial, and many find it just too hard to swallow. More seriously, Christopher Fuchs, a long term visitor and physicist at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, believes it is a contentless interpretation, that is, it doesn't tell us anything beyond the Copenhagen interpretation that could lead to new developments in quantum foundations.

"It was a reaction to the Copenhagen interpretation that went in a particular direction, and it was a healthy move because ultimately one does want to get away from thinking about observers as an integral part of quantum mechanics and it does do that," says Fuchs. "But, what price do you pay for a view of the world that is not very particular to that world?"

Exposing the past

Byrne doesn't have a science background, but he believes that his investigative journalism past has been a major asset in uncovering Everett's story. "One of my skills is to read through vast amounts of government gobbledy-gook and emerge with some interesting facts. Well, now I've read through vast numbers of physics papers — although I read around the equations for the most part — and emerged with enough interesting facts for a book."

Shenker agrees that, as journalist, Byrne illuminates new aspects of Everett's life, giving a very detailed picture of a great scientist who had deep human flaws.

"Peter teased out through documents, essential elements of the story," says Shenker. "It's not just a question of taking an article in print and trying to understand what it means. It's digging deep beneath the surface and finding real evidence of what's going on among the human beings that wrote this story."

So, does Byrne believe that there is a world where Everett didn't live a tortured, miserable life?

"When you look at how people are dealing with probability in the branching universe, our universe is more or less what most universes are like that Everett could have ended up in, so in most universes he wasn't a very happy camper," says Byrne. "But, there still would be uncountable numbers in which he was not only happy but his theory won the Nobel Prize."