[Marxism] No Escape From Black Holes? Stephen Hawking Points to a Possible Exit

Louis Proyect lnp3 at panix.com
Tue Jun 7 07:24:01 MDT 2016


(I find myself utterly captivated by these kinds of articles even if I 
can't understand a single word.)

NY Times, June 7 2016
No Escape From Black Holes? Stephen Hawking Points to a Possible Exit
By DENNIS OVERBYE

CAMBRIDGE, Mass. — “A black hole has no hair.”

That mysterious, koan-like statement by the theorist and legendary 
phrasemaker John Archibald Wheeler of Princeton has stood for half a 
century as one of the brute pillars of modern physics.

It describes the ability of nature, according to classical gravitational 
equations, to obliterate most of the attributes and properties of 
anything that falls into a black hole, playing havoc with science’s 
ability to predict the future and tearing at our understanding of how 
the universe works.

Now it seems that statement might be wrong.

Recently Stephen Hawking, who has spent his entire career battling a 
form of Lou Gehrig’s disease, wheeled across the stage in Harvard’s 
hoary, wood-paneled Sanders Theater to do battle with the black hole. It 
is one of the most fearsome demons ever conjured by science, and one 
partly of his own making: a cosmic pit so deep and dense and endless 
that it was long thought that nothing — not even light, not even a 
thought — could ever escape.

But Dr. Hawking was there to tell us not to be so afraid.

In a paper published to be published this week in Physical Review 
Letters, Dr. Hawking and his colleagues Andrew Strominger of Harvard and 
Malcolm Perry of Cambridge University in England say they have found a 
clue pointing the way out of black holes.

“They are not the eternal prisons they were once thought,” Dr. Hawking 
said in his famous robot voice, now processed through a synthesizer. “If 
you feel you are trapped in a black hole, don’t give up. There is a way 
out.”

Black holes are the most ominous prediction of Einstein’s general theory 
of relativity: Too much matter or energy concentrated in one place would 
cause space to give way, swallowing everything inside like a magician’s 
cloak.

An eternal prison was the only metaphor scientists had for these 
monsters until 40 years ago, when Dr. Hawking turned black holes upside 
down — or perhaps inside out. His equations showed that black holes 
would not last forever. Over time, they would “leak” and then explode in 
a fountain of radiation and particles.

Ever since, the burning question in physics has been: When the black 
hole finally goes, does it give up the secrets of everything that fell in?

Dr. Hawking’s calculation was, and remains, hailed as a breakthrough in 
understanding the connection between gravity and quantum mechanics, 
between the fabric of space and the subatomic particles that live inside 
it — the large and the small in the universe.

But there was a hitch. By Dr. Hawking’s estimation, the radiation coming 
out of the black hole as it fell apart would be random. As a result, 
most of the “information” about what had fallen in — all of the 
attributes and properties of the things sucked in, whether elephants or 
donkeys, Volkswagens or Cadillacs — would be erased.

In a riposte to Einstein’s famous remark that God does not play dice, 
Dr. Hawking said in 1976, “God not only plays dice with the universe, 
but sometimes throws them where they can’t be seen.”

But his calculation violated a tenet of modern physics: that it is 
always possible in theory to reverse time, run the proverbial film 
backward and reconstruct what happened in, say, the collision of two 
cars or the collapse of a dead star into a black hole.

The universe, like a kind of supercomputer, is supposed to be able to 
keep track of whether one car was a green pickup truck and the other was 
a red Porsche, or whether one was made of matter and the other 
antimatter. These things may be destroyed, but their “information” — 
their essential physical attributes — should live forever.

In fact, the information seemed to be lost in the black hole, according 
to Dr. Hawking, as if part of the universe’s memory chip had been 
erased. According to this theorem, only information about the mass, 
charge and angular momentum of what went in would survive.

Nothing about whether it was antimatter or matter, male or female, sweet 
or sour.

A war of words and ideas ensued. The information paradox, as it is 
known, was no abstruse debate, as Dr. Hawking pointed out from the stage 
of the Sanders Theater in April. Rather, it challenged foundational 
beliefs about what reality is and how it works.

If the rules break down in black holes, they may be lost in other places 
as well, he warned. If foundational information disappears into a gaping 
maw, the notion of a “past” itself may be in jeopardy — we couldn’t even 
be sure of our own histories. Our memories could be illusions.

“It’s the past that tells us who we are. Without it we lose our 
identity,” he said.

Fortunately for historians, Dr. Hawking conceded defeat in the black 
hole information debate 10 years ago, admitting that advances in string 
theory, the so-called theory of everything, had left no room in the 
universe for information loss.

At least in principle, then, he agreed, information is always preserved 
— even in the smoke and ashes when you, say, burn a book. With the right 
calculations, you should be able reconstruct the patterns of ink, the text.

Dr. Hawking paid off a bet with John Preskill, a Caltech physicist, with 
a baseball encyclopedia, from which information can be easily retrieved.

But neither Dr. Hawking nor anybody else was able to come up with a 
convincing explanation for how that happens and how all this 
“information” escapes from the deadly erasing clutches of a black hole.

Indeed, a group of physicists four years ago tried to figure it out and 
suggested controversially that there might be a firewall of energy just 
inside a black hole that stops anything from getting out or even into a 
black hole.

The new results do not address that issue. But they do undermine the 
famous notion that black holes have “no hair” — that they are shorn of 
the essential properties of the things they have consumed.

About four years ago, Dr. Strominger started noodling around with 
theoretical studies about gravity dating to the early 1960s. Interpreted 
in a modern light, the papers — published in 1962 by Hermann Bondi, M. 
G. J. van der Burg, A. W. K. Metzner and Rainer Sachs, and in 1965 by 
Steven Weinberg, later a recipient of the Nobel Prize — suggested that 
gravity was not as ruthless as Dr. Wheeler had said.

Looked at from the right vantage point, black holes might not be not be 
bald at all.

The right vantage point is not from a great distance in space — the 
normal assumption in theoretical calculations — but from a far distance 
in time, the far future, technically known as “null infinity.”

“Null infinity is where light rays go if they are not trapped in a black 
hole,” Dr. Strominger tried to explain over coffee in Harvard Square 
recently.

 From this point of view, you can think of light rays on the surface of 
a black hole as a bundle of straws all pointing outward, trying to fly 
away at the speed of, of course, light. Because of the black hole’s 
immense gravity, they are stuck.

But the individual straws can slide inward or outward along their futile 
tracks, slightly advancing or falling back, under the influence of 
incoming material. When a particle falls into a black hole, it slides 
the straws of light back and forth, a process called a supertranslation.

That leaves a telltale pattern on the horizon, the invisible boundary 
that is the point of no return of a black hole — a halo of “soft hair,” 
as Dr. Strominger and his colleagues put it. That pattern, like the 
pixels on your iPhone or the wavy grooves in a vinyl record, contains 
information about what has passed through the horizon and disappeared.

“One often hears that black holes have no hair,” Dr. Strominger and a 
postdoctoral researcher, Alexander Zhiboedov, wrote in a 2014 paper. Not 
true: “Black holes have a lush infinite head of supertranslation hair.”

Enter Dr. Hawking.

For years, he and Dr. Strominger and a few others had gotten together to 
work in seclusion at a Texas ranch owned by the oilman and fracking 
pioneer George P. Mitchell. Because Dr. Hawking was discouraged from 
flying, in April 2014 the retreat was in Hereford, Britain.

It was there that Dr. Hawking first heard about soft hair — and was very 
excited. He, Dr. Strominger and Dr. Perry began working together.

In Stockholm that fall, he made a splash when he announced that a 
resolution to the information paradox was at hand — somewhat to the 
surprise of Dr. Strominger and Dr. Perry, who has been trying to 
maintain an understated stance.

Although information gets hopelessly scrambled, Dr. Hawking declared, it 
“can be recovered in principle, but it is lost for all practical purposes.”

In January, Dr. Hawking, Dr. Strominger and Dr. Perry posted a paper 
online titled “Soft Hair on Black Holes,” laying out the basic 
principles of their idea.

In the paper, they are at pains to admit that knocking the pins out from 
under the no-hair theorem is a far cry from solving the information 
paradox. But it is progress.

Their work suggests that science has been missing something fundamental 
about how black holes evaporate, Dr. Strominger said. And now they can 
sharpen their questions. “I hope we have the tiger by the tail,” he said.

Whether or not soft hair is enough to resolve the information paradox, 
nobody really knows. Reaction from other physicists has been reserved.

Juan Maldacena of the Institute for Advanced Study in Princeton, N.J., 
said of the new proposal, “Its significance for the black hole 
information problem remains to be seen. But it is probable that it plays 
some role.”

Escape Plans?

Dr. Strominger has serious street cred when it comes to black holes. In 
a celebrated calculation in 1996, he and Cumrun Vafa computed the 
information content of a black hole, verifying Dr. Hawking’s famous 
conjecture that black holes explode.

Their work is still one of the greatest achievements of string theory, 
the vaunted and yet unproved theory of everything. If this estimate of 
the content in a black hole matches one made from supertranslations, 
physicists would arrive at a fundamental, new understanding of how they 
work.

But Dr. Strominger and Dr. Perry admit that they are not anywhere near 
doing that yet. In a new paper not yet released, Dr. Strominger said 
that they had been able to show that information could also be encoded 
in the twisting of light beams trying to escape from the black hole, not 
just their sliding back and forth.

At Harvard last month, Dr. Hawking, who has a taste for dramatic 
statements, doubled down on his Stockholm declaration.

“When I wrote my paper 40 years ago, I thought the information would 
pass into another universe,” he told me. Now he thinks the information 
is stored on the black hole’s horizon.

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“The information will be re-emitted when the black hole evaporates. My 
work with my colleagues Andy Strominger of Harvard and Malcolm Perry of 
Cambridge has shown us the mechanism for information retrieval from a 
black hole.”

You could even get out of a black hole, at least in principle. Limits 
can always be transcended.

Dr. Hawking himself is proof enough.

He has long been confined to a wheelchair, yet raised three children, 
published the best-selling “A Brief History of Time,” lost his voice to 
a tracheotomy, divorced, remarried, divorced again. He has become 
something of a pop icon. Last week, he called Donald J. Trump a “demagogue.”

He has survived several pneumonia episodes. Prior to his appearance in 
Boston, he arrived in New York on a Swiss ambulance airplane with a 
retinue that includes nurses and an IT expert to keep his computer and 
voice synthesizer working. His intellect is perhaps exceeded only by his 
stubbornness.

Dr. Hawking and his colleagues worked in a hotel by day and were feted 
at night, including a party at the home of the media baron Rupert Murdoch.

The considerable expense was covered by Yuri Milner, a Russian 
philanthropist and entrepreneur, who wanted Dr. Hawking on hand to help 
announce a new project to see if we can fly iPhone-like spaceships to 
Alpha Centauri, the nearest star.

“What makes humans unique?” Dr. Hawking asked rhetorically during the 
ceremony atop One World Center. “Gravity keeps us down, but I flew here 
on an airplane. I lost my voice, but I can speak through a voice 
synthesizer.”

“How do we transcend these limits?” he went on. “With our minds and our 
machines.”




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