The cosmologist and pop-science icon Stephen Hawking, who died last March on Einstein's birthday, spoke recently in the form of his latest scientific work from the grave. Fitting for a man on the other side in the newspaper is about how to escape a black hole.
Purified from his abstract mathematics, the paper is an ode to memory, loss and the oldest human yearning, the desire for transcendence. As the damn character in Bruce Springsteen's "Atlantic City" sings, "Everything dies, baby, that's a fact, but maybe everything that dies someday will come back."
Black holes are objects that are not so dense according to Einstein's law of general relativity, even light can escape. In 1974 Dr. Hawking these objects and the rest of the physics from the inside out. He discovered to his surprise that the random quantum effects that govern the microscopic world leach black holes and eventually explode and disappear.
In the fullness of time (which in many cases would be longer than the current age of the universe), all the mass and energy that had fallen into the hole would come out again. But according to the classical Einstein equations, black holes are disturbingly simple; their only properties are mass, electric charge and angular momentum. Every other detail about what falls into a black hole disappears from the memory banks of the universe. A black hole has no complications – no hair – that was the saying.
So the Well of Matter and Energy emanating from a black hole would be accidental. Hawking emphasized in 1975 in a newspaper. If you fell in one and came back, you would miss all the details you have made: male or female, blue eyes or brown, Yankee fan or Red Sox fan. The equation that describes this fate is on Dr. Hawking's grave stone is inscribed in Westminster Abbey, where it is likely to outlast the ages.
This is a kind of incarnation . If nature can forget you, it could forget everything – a killing blow to science's ability to reconstruct the past or predict the future. "It's the past that tells us who we are," Dr. Hawking at a conference in Harvard several years ago. "Without it we lose our identity."
In fact, Dr. Hawking in his 1975 work added the paradoxical quantum effects that Einstein once dismissed by saying that God does not roll dice, adding an additional forgetfulness to nature. "God does not just dice," wrote Dr. Hawking, "but he often throws them where they can not be seen."
They fought with other physicists; It was a fundamental principle that the proverbial film of history can run backwards to reconstruct what happened, for example, in the collision of two subatomic particles in a high-energy collider.
The last few years have brought a ray of hope. Harvard's Andrew Strominger discovered that black holes, when viewed from the right mathematical perspective – that of a ray of light that faces the infinite future – are more complicated than we thought. You have what Dr. Strominger has called "soft hair" in the form of these imaginary rays of light that can be fluted, caressed, twisted and rearranged by material that enters the black hole. In principle, this hair could encode information about the surface of the black hole and record all the details that allegedly omit Einstein's equations
Whether that's enough to save physics, let alone a person falling into a black hole the Dr. Hawking worked in the years before his death.
"When I wrote my work 40 years ago, I thought the information would move to another universe," he told me at the Harvard conference. Now, he said, it's on the surface of the black hole. "The information will be broadcast again when the black hole evaporates."
Other experts, including Juan Maldacena of the Princeton Institute for Advanced Study, are doing more and saying that if soft hair does not solve the information paradox, it could at least help.
Dr. Hawking and his colleagues tried in his latest, posthumous report that caused a stir to show how this optimistic idea could work. Besides Dr. Hawking were the authors of the article. Strominger and Malcolm Perry and Sasha Haco from the University of Cambridge.
Dr. Strominger hopes physicists will one day be able to understand black holes just by reading what's in that soft hair.
"We have not proved it," he said in an e-mail. But, he added, they managed to show how all the pieces might fit together: "If our guess is correct, this paper will be central, if not, it will be a technical footnote."
Few of us , including Dr. Hawking, ever hoped that solving the information paradox would bring back our parents, the dinosaurs, or Joe DiMaggio from everything that was waiting in Atlantic City. Somewhere along the way, we all made some sort of lodging with the idea that our personal schedules will come to an end, but we comfort something about being remembered and that our genes, books and names continue
Last Year Pixar / Disney movie "Coco", which I recently saw with my daughter, tells the story of a young Mexican boy who visits the Land of the Dead to find an ancestor who can help him on his quest after a musician. The Land of the Dead is a living place, but its inhabitants can only stay there, as it turns out as long as someone remembers them. When the memories disappear, so do the animated skeletons
Some astronomers now say that even this pale version of salvation might be in danger. A mysterious force called dark energy accelerates the expansion of the universe. One day these experts say that as expansion progresses and the galaxies fly faster and faster, the rest of the universe will be out of sight forever and we will be out of sight forever. It would be like being surrounded by a black hole where all our information and memories disappeared.
Our little Bubble of the Milky Way could always remember Aretha and Cleopatra and Shakespeare and Hawking. But will the rest of the universe remember us?