Cosmic Mysteries to ponder

Top 10 Space Mysteries for 2003
December 27, 2002

By Robert Roy Britt
Senior Science Writer, SPACE.com

The funny thing about discoveries is that they often produce new mysteries, too. This year was no exception, as many remarkable space science findings generated puzzling problems for astronomers to look into.

In some cases the puzzles are brand new. Other times a discovery merely confirms how little we knew. Either way, there's plenty for astronomers to do.

Here then are the Top 10 Space Mysteries that astronomers will be pondering in the New Year and beyond:


1. Dark Energy

Nobody knows what the heck it is, but it is officially repulsive. And man is it powerful! More powerful than gravity, even.

While gravity holds things together at the local level (and by local I mean within galaxies and even between them, forming galactic clusters) some unknown force is working behind the scenes and across the universe to pull everything apart. Scientists have only come to realize this dark force in recent years, by discovering that the universe is expanding at an ever-increasing pace.

Having no clue what it is, they've labeled it dark energy.

The past year was a good one for proving that dark energy is at work. Calculations have been refined: The repulsive force dominates the universe, comprising 65 percent of its makeup.

(Similarly unseen and exotic dark matter makes up 30 percent of the universe, leaving us with a universe that contains just 5 percent normal matter and energy.)

Two curious ideas related to the accelerating expansion, both of which emerged in 2002: All galaxies are destined to become frozen in time or, perhaps, time never ends.


2. Water on Mars?

Mars simply will not give up its most coveted secrets. Ultimately, the big quest for NASA (news - web sites) and all the Mars scientists is about whether there is life, but before that's answered, there is the question of liquid water, a requirement of life as we know it.

Despite two major discoveries of water ice in 2002, nobody can figure out yet whether any of it might exist in the melted state.

Meanwhile, clues mount. In one compelling study released in December, dark streaks on the surface were attributed to salty, running water. But many experts remain unconvinced. NASA's Odyssey spacecraft is circling Mars as you read this, hunting for more evidence.

3. The Murky, Mediocre Middle of the Milky Way

Something is eating at the black hole at the center of our galaxy. And whatever is bugging the gravity monster manifests as an utter lack of appetite.

In October, astronomers announced they'd watched a star zip around the black hole that anchors the Milky Way, all but proving the impossible-to-see object is actually there. Meanwhile, the region around the black hole is an active place, as the Chandra X-ray Observatory showed early this year.

However, the black hole is not devouring enough matter to generate the tremendous X-ray output seen with other supermassive black holes. Scientists are so far unable to fully explain the stark contrasts they've seen, this tremendous diversity in black hole behavior.

Hints emerged this year, however. A study in January suggested mergers between two black holes might serve as an on-off switch for the activity. Then observations announced in November showed two black holes involved in a pending merger. Astronomers now need to tie all this to a firm explanation of the differences between the mediocre output of our black hole and the brilliant illumination surrounding others in many distant galaxies.


4. The Origin of Life

Have you ever had one of those dreams where you try to run from a monster and you're legs go 'round and 'round but you don't get anywhere? The quest to understand the origin of life isn't much different.

In fairness, it must be pointed out that there is little data to work with. Earth does not retain a record of what went on billions of years ago, when life got going.

Meanwhile, there is no shortage of wild ideas. Scientists now generally agree that life could survive a trip to Earth from Mars, in the belly of a rock kicked up by an asteroid impact. A study in November revealed why a Mars rock lands on Earth once a month, on average. A wilder idea, that bugs simply rain down from space inside comet dust, gained support from a second scientist in December, who claimed to have found some of these space bugs in Earth's atmosphere.

Most mainstream scientists, however, figure there's a good chance that life on Earth was cooked up in a soup of pre-biotic chemicals right here on the planet. The ingredients -- water and organic chemicals -- may well have come from space, but Earth likely acted as the incubator.

The answer (and a lot of well-funded researchers are asking the question and debating the possibilities) bears on how likely it is that life might have begun elsewhere, on Mars or around another star.


5. Lunar Secrets

No place beyond Earth is more well studied than the Moon. We went there, stomped around. Sifted the soil. Brought some rocks back. But the Moon still holds many secrets. The most profound might be rocks launched from Earth billions of years ago by asteroid impacts.

These storehouses of terrestrial information have been presumed for years to exist on the Moon; this July an attempt was made to quantify them. The estimate: 11,000 pounds of Earth stuff sits within a few inches of the surface for every square mile on the Moon.

The rocks should hold information about the composition of the young Earth and its atmosphere, and possibly even the origin of life. This information is not available anywhere else because, unlike the Moon, Earth continually recycles its surface material, folding it inward and melting it beyond recognition.

Nobody can say for certain this stuff is there, or whether it can be retrieved, but researchers are optimistic.

"This [new study] gives us a compelling reason to go back -- to look at the Moon as a window to early Earth," said study leader John Armstrong of the University of Washington. He added that it would be the fastest and cheapest way to learn about planet's early years and the formation of the whole solar system.


6. Are We Alone?

If only we could click our heels and be swept off to another Earth, we'd know. Meanwhile, we're all stuck here on this planet with arguably lousy cosmic eyesight, forced to indirectly detect the presence of worlds around other stars, left to wonder if they might harbor life.

So far the worlds we find are huge, most bigger than Jupiter. Prior to 2002, every one of them orbited so close to its host star as to be decidedly strange by the standards of our solar system. This forced us to question whether ours is standard at all.

In June, however, new "Jupiters" were found in orbits similar to our own beloved gas giant.

Now the pressure is on to find smaller planets, and one study this year estimated there are billions of them out there. Few doubt the presence of at least some rocky planets in Earth-like orbits. But don't bet on any proof coming 2003. This is a mystery that probably won't be solved until a new generation of space telescopes goes into orbit, mid-decade at the soonest.

Meanwhile, another study this year estimated the chances for extraterrestrial life on Earth-like planets is 1-in-3.

Most scientists, when they talk about ET, would be thrilled to find microbes. The folks over at the SETI Institute, on the other hand, are listening for intelligent life, perhaps animals like us (or really smart microbes). While they may never get a signal, it could happen in 2003.


7. The Enigmatic Sun

If you're looking for a career with a really bright future, become a solar physicist. Amazingly, we still don't fully understand the dynamics of the star we orbit.

New pictures of sunspots in 2002, the most detailed ever, revealed canal-like structures reaching from bright regions into the dark hearts of sunspots. The strange structures are fueled by the Sun's tremendous heat and magnetic energy, but beyond that, their generation is a mystery.

"Exactly what happens and why these kind of structures are formed, we don't know," said study member Dan Kiselman.

And the Sun in general? "The amazing zoo of structures and dynamic phenomena on the Sun are not well understood in general, though they have been observed for a very long time," Kiselman said. Sounds like serious job security.


8. Age of the Universe

Scientists pretty much agree on the general method by which the early universe evolved. But they start to argue when the topic of the universe's actual age comes up.

The age of the universe has been put at 12 billion to 15 billion years for some time now, but every few months a revision or refinement is announced. Hubble Telescope observations yielded in April an estimate of 13-14 billion years.

We can't say when a firm answer will be presented, but we can predict the likelihood of another estimate sometime in 2003.

(A related and even more vexing set of questions: What exactly happened at the beginning of the universe, and what existed before that instant? These are questions cosmologists will likely wrangle with forever, since no direct observations can be made of those time frames and therefore, presumably, no proof can come.)


9. Missing Planets

Imagine the surprise of a really smart scientist who runs the latest computer model, loaded with a decades-old, widely accepted theory about how our solar system formed, and the computer spits out a diagram with only seven planets.

Uranus and Neptune have been missing, in theory, for some time now. The problem arises because the standard model of planet formation requires material to crash together and stick over millions of years. Once a large core is built, gas can be attracted to create planets like Jupiter and Saturn. But out where Neptune and Uranus roam, there would never have been enough hard material for this to work.

This year, theorist Alan Boss of the Carnegie Institution of Washington put forth a radical new idea, a planet-formation mechanism that conveniently builds the two outer ice giants, too. Boss figures the four big planets in our solar system did not develop from rocky cores, as the standard model once held, but that they collapsed from large gas and dust clouds.

To round out his theory, and the planets, Boss had to put our fledgling solar system in another part of space. He chose a region of intense star formation, so that the UV radiation from a nearby star could strip Uranus and Neptune down to fighting weight. The solar system then migrated to its present, more pleasant region of the galaxy.

All well and good, but other astronomers are very skeptical. We're left with an old theory that doesn't work and a new one that is, in the words of its creator, a wild idea.

Maybe in 2003, while some scientists are busy looking for planets around other stars, someone will figure out for sure how the planets in our own solar system were created!


10. Can We Survive 2003?

No space news made for more dramatic headlines in 2002 than the seemingly imminent risk of asteroid impacts. Over and over.

In the most celebrated case, an asteroid with a tiny chance of hitting Earth in the year 2019 was overhyped by the media in July, only to have the odds downgraded days later. The scenario is one that seems to repeat at least once a year.

For now, there are no space rocks known to be on a collision course with Earth. At the same time, there are tons of them out there that have not been found. Particularly taxing for astronomers will be the small objects, which roam space by the millions, could devastate a region of the planet, and all of which probably won't be catalogued for decades to come, if ever.

Meanwhile, asteroids continue to present new puzzles that make it difficult to imagine what to do with one that might be headed our way. Some seem to be relatively solid chunks of stone or metal. Others appear to be rubble piles, loosely bound smaller rocks. Blowing one of these up would have dramatically varying consequences based on the composition of the targeted material.

Importantly, the tally of asteroids with companion moons rose above 30 during 2002. Many other such pairs await discovery. Deflecting or destroying an incoming pair of rocks would present a daunting challenge to engineers who don't yet know how to deal with a lone asteroid.

For those who might worry, odds are good we can survive 2003, at least in terms of the threat from space rocks. And the chances are good that if a big one is coming our way, we'll know about it years if not decades in advance, astronomers say.

The challenge for scientists, however, is to begin a concerted effort to find smaller asteroids and unravel the remaining mysteries of this wildly diverse category of objects and to do so before they find one bearing down on our planet.

Top 10 Cool Moon Facts

Top 5 Cosmic Myths

5 Great Cosmic Mysteries

10 Confounding Cosmic Questions

Top 10 Apollo Era Moon Discoveries

Top 10 Space Science Images of 2002 (SPACE.com)

Now the pressure is on to find smaller planets, and one study this year estimated there are billions of them out there. Few doubt the presence of at least some rocky planets in Earth-like orbits. But don't bet on any proof coming 2003. This is a mystery that probably won't be solved until a new generation of space telescopes goes into orbit, mid-decade at the soonest.

Lazarus Long,

Are we alone?

Is faster than light travel possible?

Great questions!

bob

This topic thread is for astrophysics, cosmology, and the associated theories and phenomena that we need to study for a clearer image of our Universe conseptually. Many subjects we are describing here at Imminst overlap into this area of study but we should perhaps start by reviewing some articles and serious theoretical explainations and then follow-up with some discussion of the key issues. Please, let us all begin.

E and mc2: Equality, It Seems, Is Relative
By DENNIS OVERBYE

Roll over, Einstein.

In science, no truth is forever, not even perhaps Einstein's theory of relativity, the pillar of modernity that gave us E=mc2.

As propounded by Einstein as an audaciously confident young patent clerk in 1905, relativity declares that the laws of physics, and in particular the speed of light — 186,000 miles per second — are the same no matter where you are or how fast you are moving.

Generations of students and philosophers have struggled with the paradoxical consequences of Einstein's deceptively simple notion, which underlies all of modern physics and technology, wrestling with clocks that speed up and slow down, yardsticks that contract and expand and bad jokes using the word "relative."

Guided by ambiguous signals from the heavens, and by the beauty of their equations, a few brave — or perhaps foolhardy — physicists now say that relativity may have limits and will someday have to be revised.

Some suggest, for example, the rate of the passage of time could depend on a clock's orientation in space, an effect that physicists hope to test on the space station. Or the speed of a light wave could depend slightly on its color, an effect, astronomers say, that could be detected by future observations of gamma ray bursters, enormous explosions on the far side of the universe.

"What makes this worth talking about is the possibility of near-term experimental implications," said Dr. Lee Smolin, a gravitational theorist at the Perimeter Institute for Theoretical Physics in Ontario.

Any hint of breakage of relativity, scientists say, could yield a clue to finding the holy grail of contemporary physics — a "theory of everything" that would marry Einstein's general theory of relativity, which describes how gravity shapes the universe, to quantum mechanics, the strange rules that govern energy and matter on subatomic scales.

Even Einstein was stumped by this so-called quantum gravity.

For now, any clue would be welcome. There is very little agreement and much confusion about the possible end of relativity. "These are times when theorists are being very adventurous," said Dr. Andreas Albrecht, a physicist at the University of California at Davis. "It's hard to tell where things will go."

The avatars of new relativity have been encouraged by hints that some cosmic rays hitting Earth from outer space have more energy than normal physics can explain. But some scientists doubt that these rays exist or, if they do, that a violation of relativity is the only way to explain them.

The cosmic ray hints are not the only signs making physicists wonder about relativity. They have also been tantalized by evidence, as yet unconfirmed, from distant quasars that a fundamental constant of nature, a measure of the strength of electromagnetism known as the fine-structure constant, might have changed ever so slightly over billions of years, shifting the wavelengths of light emitted by the quasars.

The result has been a minor explosion of interest in strange relativity, with some 70 papers being published this year, said Dr. Giovanni Amelino-Camelia, a theorist at the University of Rome.

The field, while still small, is destined for at least 15 minutes of fame next year with the publication in February of "Faster Than the Speed of Light," by Dr. João Magueijo, a cosmologist at Imperial College London. The book is a racy account of Dr. Magueijo's seemingly heretical effort to modify relativity so that the speed of light is not constant, and he will promote it on a long lecture tour.

"Ruling out special relativity by 2005 is a bit extreme," Dr. Magueijo said in a recent e-mail message, referring to the coming centennial of Einstein's famous paper, "although I would be very surprised if by 2050 nothing beyond relativity has been found."

Most physicists have yet to buy into this presumed revolution. Dr. Edward Witten of the Institute for Advanced Study in Princeton, called recent arguments that some versions of quantum gravity would violate relativity "unimpressive."

Dr. Juan Maldacena of Harvard said he doubted relativity was violated in string theory — the leading candidate for a theory of everything. "But of course," he noted, "we should always test our theories."

Dr. Carlo Rovelli, a gravitational theorist at the University of the Mediterranean in Marseille, said it was a "risky" hypothesis, "but the prize if it happened to be true is so great that it is worthwhile taking the risk of exploring it in detail."

Dr. Andrew Strominger of Harvard pointed out that Einstein himself modified relativity in 1915, when he brought gravity into the picture with his general theory of relativity. Special relativity, as the 1905 theory became known, is only strictly valid in flat space without gravity, Dr. Strominger said.

He added, "It is natural to think that Einstein's relativity will in some sense be violated by small corrections, just as Newton's theory of gravity has small corrections." These corrections did not make Newton wrong, he said, they just meant his theory was not always perfectly applicable. Likewise, relativity may give way to a more complete and accurate theory.

How relativity could break down, if it does, depends on how physics might accomplish its grand dream of quantum gravity .

Many physicists are placing their bets on string theory's mathematically imposing edifice in which nature comprises tiny strings vibrating in 10 dimensions of space-time. But this theory may play out in billions of ways, and some physicists complain that it can be made to predict almost anything.

In the late 1980's, Dr. V. Alan Kostelecky, a particle physicist at Indiana University, and his colleagues pointed out that in some of these solutions, the spins of the strings could impart an orientation to empty space, like the lines left by the weave in a fine cloth. In that case, they say, a clock oriented in one direction could tick slightly faster or slower than one oriented differently, in violation of the rules of relativity. That is something Dr. Kostelecky and his colleagues have proposed to test using ultraprecise clocks on the space station.

Dr. Kostelecky and his colleagues have constructed an extension to the standard model of particle physics that catalogs all the possible ways that relativity can be violated. Others, including Dr. Amelino-Camelia, Dr. John Ellis of CERN, Dr. Tsvi Piran of the Hebrew University in Jerusalem and the Harvard theorists Dr. Sheldon Glashow and Dr. Sidney Coleman, have attempted to study the ways that relativity can be violated by quantum gravity or in the high-energy cosmic rays.

Violation is not inevitable, Dr. Kostelecky said. "Is it plausible? Yes. Is it likely? Enough so that I've invested years of my life."

Few physicists would seem to have as much invested in revising relativity as Dr. Magueijo. In his book he describes how beginning in 1996 he cajoled Dr. Albrecht, then at Imperial, into pursuing with him the heretical notion that the speed of light had been much higher in the dim cosmic past as a solution to various cosmological puzzles. Cosmologists did not rally to the idea, which even Dr. Magueijo admitted violated relativity. His co-author, Dr. Albrecht, himself called it an idea that is "not even properly born yet," and said it needed to find roots "in some convincing physics."

In the intervening years, as a sideline to his day job as a conventional cosmologist, he and a growing number of comrades have continued to tinker with modifying relativity in a variety of ways that go under the umbrella name of V.S.L., for variable speed of light theories.

In the science world, the book might attract attention for its jaunty and irreverent style as well as for its content. "What the hell, it's only Einstein going out of the window . . .," he writes in one passage. In others he describes the editor at a prominent journal as a moron, his bosses at Imperial as pimps and the rival quantum gravity camps as cults.

Asked how he expected his colleagues to react to the book, he answered, "It wasn't written for them; it was written for the public." He called it "a very honest view of how scientists feel," adding, "It's the language I use normally."

The main motivation for considering V.S.L. theories, Dr. Magueijo explained, comes from the as-yet undiscovered quantum gravity. In relativity there is only one special number, the speed of light, but in quantum gravity, he explained, there is another special number, known as the Planck energy, equivalent to 1019 billion electron volts. According to quantum gravity thinking, an elementary particle accelerated to that energy will behave as if space and time themselves are lumpy and discontinuous and all the forces of nature are unified.

According to relativity, however, Dr. Magueijo explained, differently moving observers could disagree on how much energy the particle had and thus whether it was displaying quantum gravity effects or not. In short, they would disagree on what the laws of physics were.

"Perhaps relativity is too restrictive for what we need in quantum gravity," Dr. Magueijo said. "We need to drop a postulate, perhaps the constancy of the speed of light."

The most recent buzz in V.S.L. circles is about something called "doubly special relativity." In 2000, hoping to fix the cosmic ray problem, Dr. Amelino-Camelia proposed modifying the rules of relativity so that there would be a limit to the momentum that any particle could have, just as now there is a limit to the velocity.

Subsequently Dr. Magueijo and Dr. Smolin of the Perimeter Institute proposed their own doubly special version in which there is a limit to the amount of energy that an elementary particle can attain, namely the so-called Planck energy, at which the forces are unified and quantum gravity effects dominate.

One casualty of this tinkering, the V.S.L. scientists agree, will be everyone's favorite formula, E=mc2, to be replaced by a more complicated, cumbersome equation that Dr. Magueijo reproduces in his book.

A mark of all the doubly special theories, Dr. Magueijo said, is that the speed of light will vary with its color, with higher frequencies and energies going slightly faster than lower ones. That might manifest itself in observations of gamma ray bursters, distant gargantuan outbursts by an upcoming NASA satellite called Glast (gamma ray large area space telescope), scheduled for launching in 2006.

The theory also predicts that light should slow down near massive objects and actually come to a stop at the end of a black hole, preventing anything from entering that dark gate, Dr. Magueijo said in his book. In principle the effect, he said, could be tested by spectroscopic measurements of the light emitted from dense objects like neutron stars.

To some physicists, however, the very idea of variations in the speed of light in a vacuum — the c in E=mc2 — is meaningless. The miles and seconds by which speed is measured are human inventions, they point out, defined in fact in terms of lightwaves, so the whole notion of the speed of light varying is circular. In the last analysis, they point out, all physical measurements boil down to a few dimensionless constants like the fine structure constant, alpha. "What we measure objectively is whether alpha varies," said Dr. Michael Duff of the University of Michigan in an e-mail message.

Dr. Magueijo said those criticisms were technically correct but said the speed of light was one factor of several in the formula for alpha. So if alpha varied, as some astronomical measurements have suggested, one could choose to think of it as a variation in the speed of light, of electric charge, or even a variation in another number known as Planck's constant — or all three — if that made the math simpler. "It's a matter of convention," he said, adding, "you make the simplest choice."

Despite all the activity, scientists agree that they are mostly in the dark about the deeper consequences of these conjectures. "Some may eventually be developed to the point of being a credible alternative to relativity," conceded Dr. Kostelecky, saying that he suspected that others might not really change relativity or might have already been excluded by existing experiments. Without a systematic analysis it was impossible to know.

Dr. Amelino-Camelia said that the doubly special theories preserve Einstein's principle that all motion is relative, but at an unknown cost to the rest of physics."We paid a dramatic price for relativity: the notion of absolute time," he said. "This time it is not completely sure what is the axiomatic principle we have to give up."

Dr. Albrecht urged caution and said physicists needed guidance from experiments before tossing out beloved principles like relativity. "The most dignified way forward," he said, "is to be forced kicking and screaming to toss them out."

Edited by Lazarus Long, 22 May 2003 - 11:40 PM.

New formulas for old ideas.

Chandra X-ray Observatory images of two distant massive galaxies show they are enveloped by vast clouds of high-energy particles that are evidence for past explosive activity. In both galaxies radio and X-ray jets allow this activity to be traced back to central supermassive black holes. The jets are heating gas outside the galaxies in regions hundreds of thousands of light years across.

http://www.space.com...wth_030522.html
Big Black Holes
By SPACE.com Staff
posted: 09:00 am ET 22 May 2003

Mother Nature apparently has a weight limit for galaxies with supermassive black holes at their cores.

Astronomers using NASA's Chandra X-ray Observatory found a pair of large galaxies whose black hole centers appear to regulate their growth based on its amount of energy. If the energy level is high enough matter can avoid falling into the all-consuming black hole, too low and it gets gobbled up.

The research stems from observations of vast clouds of high-energy particles surrounding two large galaxies. The galaxies, known as 3C294 and 4C41.17, are 10 million and 12 billion light-years from Earth, respectively. Their energy clouds, researchers said, are the remains of past explosive events that stemmed from central supermassive black holes.

"These galaxies are revealing an energetic phase in which a supermassive black hole transfers considerable energy into the gas surrounding the galaxies," said Andrew Fabian, lead author of the study on 3C294, in a written statement. "This appears to be crucial in explaining the puzzling properties of present-day galaxies, especially those that group together in large clusters," he said. Fabian, a professor at Cambridge University, will publish his findings in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.

The studies of both galaxies suggest a kind of a cosmic circle of galactic life. As a dense region of intergalactic gas cools, it forms several smaller galaxies that later merge to form a larger galaxy with a supermassive black hole at its core. Both galaxy and black hole continue to grow by absorbing other nearby galaxies.

This growth, however, appears to halt when energy generated by the jets produced around the black hole heat up the galaxy's gas until it is energetic enough to avoid being sucked into the cosmic pit. This seems to occur once a galaxy reaches a mass about 12 times that of our own Milky Way, researchers said.

Millions of years after the jet activity dies down, matter again starts falling into the black hole and the cycle starts all over again, with the galaxy growing in fits like a car in stop-and-go traffic.

"It's as if nature tries to impose a weight limit on the size of the most massive galaxies," said Caleb Scharf, lead author of the study on galaxy 4C41.17 and a professor at New York's Columbia University. "The Chandra observations have given us an important clue as to how this occurs. The high-energy jets give the supermassive black holes an extended reach to regulate the growth of these galaxies," he said. Scharf's research will appear in the Astrophysical Journal.

These magnetized jets of high-energy particles sweep up clouds of dust and gas and help trigger the formation of billions of new stars. The dusty, star-forming clouds of 4C41.17, the most powerful source of infrared radiation ever observed, are embedded in even larger clouds of gas.

Reseachers found these larger clouds to have a temperature of about 10,000 degrees. But the clouds are leftover material from the galaxy's formation and should have cooled rapidly by radiation in the absence of a heat source.

"Significantly, the warm gas clouds coincide closely with the largest extent of the X-ray emission," said Michiel Reuland of Lawrence Livermore National Laboratory in Livermore, Calif. Reuland is a a co-author on the 4C41.17 study. "The Chandra results show that high-energy particles or radiation can supply the necessary energy to light up these clouds," he said.

Most of the X-rays from 4C41.17 and 3C294 are caused by collisions of energetic electrons with the cosmic background photons from the early days of the universe. Because these galaxies are far away, their observed radiation originated when the universe was younger and the background was more intense. This effect enhances the X-radiation and helps astronomers to study extremely distant galaxies.

http://www.space.com...eds_030326.html


This quasar is at a distance of over 5 billion light years from Earth, a redshift of 3.91. This is an X-ray image captured by the orbiting Chandra X-ray Observatory. APM 08279 5255 is magnified naturally through gravitational lensing by a factor of about 100. This means that the quasars light, while en route to us, was distorted and magnified by the gravity of intervening galaxies acting like telescope lenses. CREDIT: NASA/CXC/G. Chartas et al.

Black Holes Blow Matter into Space with Tremendous Wind, Study Finds
By Robert Roy Britt Senior Science Writer
posted: 08:30 am ET 26 March 2003

Astronomers know that black holes spit energy back into space as they voraciously consume matter in a process that is not entirely efficient. Now it seems they propel matter outward, too, in a wind to end all winds.

Theory had predicted the fast-moving exodus of stuff, but no one had ever seen it happening. A new study found evidence of hydrogen, carbon, oxygen and iron rushing out from the vicinities of two separate black holes in winds of material moving at some 40 percent the speed of light, faster than astronomers expected.

The black holes are supermassive, weighing as much as millions or billions of regular stars and anchoring two distant, bright and fledgling galaxies called quasars. Quasars are thought to be surrounded by vast reservoirs of gas, which tends to move toward the center and fuel star birth while also feeding the black hole. The chaos leads to intensely bright objects which, astronomers believe, settle down and become conventional galaxies over time.

"The winds we measured imply that as much as a billion suns' worth of material is blown away over the course of a quasar's lifetime," said Penn State's George Chartas, who led the observations.

The wind is created by differences in radiation pressure, Chartas and his colleagues said, somewhat like how differences in air pressure create wind on Earth.

The winds might help regulate black hole growth, thwarting other incoming material that is compelled to spiral inward at the request of the black hole's gravity, Chartas and his colleagues say. The outrushing wind might also spur the creation of new stars, by causing pressure and temperature knots in the overall gas cloud.

Observations were made with NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite and announced today at a meeting of the High Energy Astrophysics Division of the American Astronomical Society at Mt. Tremblant, Quebec.


Quasar PG 1115+080: This quasar is at a distance of over 5 billion light years from Earth, a redshift of 1.72. This is an X-ray image captured by the orbiting Chandra X-ray Observatory.


The winds originate in a disk of material spiraling inward. This accretion disk of gas and dust is accelerated to ever-faster speeds before some of the matter disappears beyond a sphere of no return, the so-called event horizon of a black hole. Astronomers already knew with relative certainty that the process can create two jets of energy that shoot out along the black hole's axis of rotation. Other radiation emanating from the scene in all directions has also been imaged.

But by spotting evidence of matter pushing outward, researchers think they're on a path toward better understanding of how galaxies and their central black holes evolve.

"The wind might provide insight to the relationship between black hole mass and the central bulge of its host galaxy," said Niel Brandt, a Penn State researcher also involved in the discovery.

Only recently have other research teams begun to weigh the black holes in the most distant quasars. Theory holds that the black holes should typically contain less than 1 percent of the mass of the overall galaxy.

The study examined quasars called APM 08279+5255 and PG1115+080. Both are billions of light-years away but were magnified as their light was distorted by the gravity of intervening galaxies. This natural process, called gravitational lensing, allows astronomers to see distant objects in greater detail.

Gordon Garmire of Penn State and Sarah Gallagher of MIT also worked on the study.

http://www.space.com...rth_030319.html

Some internal engine, perhaps the collapse of a massive star, fuels a relatavistic jet of particles that collides with material to produce shock waves, and reverse shocks. This heats the material and produces light and gamma rays.

Birth of a Black Hole is Messy, New Observations Suggest
By Robert Roy Britt Senior Science Writer
posted: 02:19 pm ET 19 March 2003

The almost instant detection of a powerful deep-space energy burst, and the rapid follow-up by 33 telescopes around the world, has provided compelling evidence for the explosive birth of a black hole.

The aftermath appeared to be very messy, said astronomers who watched the event's energy output decline more slowly than had ever been seen before.

The observations were the most detailed ever made of a faraway explosive event known as a gamma-ray burst, or GRB. A study of the data, collected over several weeks, strengthens the connection between mysterious GRBs and even more mysterious black holes.


Hidden process

One way to make a black hole, theorists agree, is to explode a very massive star. In one of these supernova events, outer portions of the star are flung into space. Some material falls back, however, and collapses into a sphere so dense that nothing, not even light, can escape.

In recent decades, astronomers have observed mysterious gamma-ray bursts coming from all directions of the sky and mostly from outside our galaxy. Studies have gradually tied the bursts to the so-called collapsar model of black hole formation. Also, research last year made a strong connection between supernovae and gamma-ray bursts.

Still, the engine driving a GRB is not known with certainty. Researchers think gamma rays and other forms of radiation, including X-rays, visible light and radio waves, are generated prodigiously as the black hole swallows additional incoming gas and dust in sloppy fashion.

More important, fresh jets of energetic particles are created by the new setup. They zoom out along the axis of rotation of the star or the resultant black hole and blast through slower-moving material that's expanding away in waves from the site of the initial explosion.

The jets move at a significant fraction of the speed of light, speeds astronomers call relativistic. When they collide with the bubbles of material, shock waves heat the material. Gamma rays and light are unleashed, theory holds.

But there are loose ends in all these theoretical connections, not the least of which is the fact that the initial moments of gamma-ray bursts have gone largely unobserved in most wavelengths. Significant optical flashes have largely eluded astronomers.

New approach

Unlike previous gamma-ray observatories, NASA's High-Energy Transient Explorer (HETE) was designed to relay its observations to Earth in real time, instead of just once per orbit.

When HETE detected a gamma-ray burst called GRB 021004 last October, a worldwide alert went out within 11 seconds. Just more than three minutes later an automated Japanese telescope, at the Institute for Physical and Chemical Research, detected an optical counterpart to the burst. Within minutes, the explosion was recorded by the Palomar 48-inch Oschin Telescope and the Near Earth Asteroid Tracking (NEAT) camera.

Soon, telescopes all over the planet, and even NASA's space-based Chandra X-ray Observatory, were pointed at the event, which occurred in a galaxy several billion light-years away (which means that the explosion actually occurred billions of years ago and its light had just arrived at Earth).

The fading optical afterglow was monitored continuously for several weeks until it ended. The initial hours proved most compelling.

"What we have observed is a very slow decay of the optical emission for the first half-hour to 2 hours after the burst," said the study's leader, Derek Fox of Caltech. "This implies continuing energy input to the shock regions of the afterglow at these times, meaning that either the GRB's central engine is continuing to operate, or that the explosion itself was a 'dirty' explosion that ejected debris with a wide range of velocities."

Either explanation, Fox told SPACE.com, is a natural fit with collapsar models.

The results will be detailed in the March 20 issue of the journal Nature.

Fox noted that this was only the second burst to be caught so quickly by optical telescopes, so the slow decay of output may turn out to be a common feature.

"The main thing we can say for certain now, that we did not know before, is that a gamma-ray burst cannot be conceived of as a single monolithic explosion," Fox said. "Rather, it seems there is some intrinsic 'messiness' to the event -- either in the sense that the engine continues to burble for some time afterwards, or in the sense of the explosion itself being dirty, that is, having slow-moving as well as highly-relativistic debris."

Mysteries remain

"The results are exciting, but perplexing," said Tsvi Piran of the Hebrew University in Israel. Piran was not involved in the research but wrote an analysis of it for Nature.

Piran said the early afterglow faded "much more slowly than had been predicted" and exhibited significant "wiggles" or flashes as it wound down. A non-uniform structure in the jets that create the gamma rays had long been predicted, Piran said, and "this may be the first evidence for its existence."

Despite the new observations, gamma-ray bursts remain largely mysterious, Fox said. Even the link between black hole formation and the bursts is not yet proven.

"At their very core, GRBs are likely to remain mysterious for a very long time," he said. "Even if we determine that GRBs are produced by collapsars, we will still be at a loss to say, for certain, what the engine of the process is. Is it the inflow of the gases from the star feeding the black hole, is it nuclear reactions in these gases, as they are crushed and heated, or is it, possibly, the spin of the black hole itself?"

This article is a must and I suggest that any of you that are serious about astrophysics take the time to link back to the original for the great links you will find there.
LL/kxs

http://www.space.com...y_030128-1.html
The New History of Black Holes: 'Co-evolution' Dramatically Alters Dark Reputation
By Robert Roy Britt Senior Science Writer
posted: 07:00 am ET 28 January 2003

Black holes suffer a bad rap. Indicted by the press as gravity monsters, labeled highly secretive by astronomers, and long considered in theoretical circles as mere endpoints of cosmic evolution, these unseen objects are depicted as mysterious drains of destruction and death.

So it may seem odd to reconsider them as indispensable forces of creation.

Yet this is the bright new picture of black holes and their role in the evolution of the universe. Interviews with more than a half dozen experts presently involved in rewriting the slippery history of these elusive objects reveals black holes as galactic sculptors.

In this revised view, which still contains some highly debated facts, fuzzy paragraphs and sketchy initial chapters, black holes are shown to be fundamental forces in the development and ultimate shapes of galaxies and the distribution of stars in them. The new history also shows that a black hole is almost surely a product of the galaxy in which it resides. Neither, it seems, does much without the other.

The emerging theory has a nifty, Darwinist buzzword: co-evolution.

As a thought exercise, co-evolution has been around for less than a decade, or as much as 30 years, depending on who you ask. Many theorists never took it seriously, and no one had much evidence to support it. Only in the past six years or so has it gained steam. And only during the past three years have observations provided rock-solid support and turned co-evolution into the mainstream idea among the cognoscenti in both black hole development and galaxy formation.

"The emerging picture of co-evolving black holes and galaxies has turned our view of black holes on its head," says Meg Urry, an astronomer and professor of physics at Yale University. "Previously, black holes were seen as the endpoints of evolution, the final resting state of most or all of the matter in the universe. Now we believe black holes also play a critical role in the birth of galaxies."

The idea is particularly pertinent to explaining how massive galaxies developed in the first billion years of the universe. And it is so new that just last week theorists got what may be the first direct evidence that galaxies actually did form around the earliest black holes.

Chicken-and-egg question

Like archeologists, astronomers spend most of their careers looking back. They like to gather photons that have been traveling across time and space since well before Earth was born, some 4.5 billion years ago. Rogier Windhorst, an Arizona State University astronomer, has peered just about as deep into the past as anyone, to an era when the universe was roughly 5 percent of its present age.

Earlier this month, Windhorst and a colleague, Haojing Yan, released a Hubble Space Telescope image showing the most distant "normal" galaxies ever observed.

Though stretched and distorted by the technique used to spot them (an intervening galaxy cluster was used as a "gravitational lens"), the newfound galaxies, Windhorst's team assures us, resemble our own Milky Way. They are seen as they existed more than 13 billion years ago, within 1 billion years of the Big Bang.

Practically side-by-side in time, discovered in separate observations made as part of the Sloan Digital Sky Survey, are compact but bright objects known as quasars. These galaxies-to-be shine brilliantly because, researchers believe, each has a gargantuan black hole at its core, whose mass is equal to a billion suns or more, all packed into a region perhaps smaller than our solar system.

The resulting gravity pulls in nearby gas. The material is accelerated to nearly the speed of light, superheated, and swallowed. The process is not entirely efficient, and there is a byproduct: An enormous amount of energy -- radio waves, X-rays and regular light -- hyper-illuminates the whole scene.

Quasars also seem to be surrounded by halos of dark matter, a cryptic and unseen component of all galaxies. Co-existing around and amongst all this, researchers are coming to realize, is a collapsing region of stars and gas as big or larger than our galaxy.

It was no coincidence that the announcements of the two findings -- distant quasars and normal galaxies --were made together at a meeting of the American Astronomical Society (AAS) Jan. 9. Co-evolution was on the minds of the discoverers.

Among co-evolution's significant impacts is its ability to render mostly moot a longstanding chicken-and-egg question in astronomy: Which came first, the galaxy or the black hole?

"How about both?" Windhorst asks. "You could actually have the galaxy form simultaneously around a growing black hole."

Urry, who was not involved in either finding but was asked to analyze them, explained it this way: "We believe that galaxies and quasars are very intimately connected, that in fact quasars are a phase of galaxy evolution. In our current picture, as every galaxy forms and collapses, it has a brief quasar phase."

So when a quasar goes dormant, what's left are the things we associate with a normal galaxy -- stars and gas swirling around a central and hidden pit of matter.

Quasars are cagey characters, however. (The term is short for quasi-stellar radio source; astronomers first mistook the objects for stars within our galaxy in the early 1960s.) When one is firing, its brightness can exceed a thousand normal galaxies. The quasar outshines its entire host galaxy so significantly that scientists have not been able to see what's really causing all the commotion. That veil is lifting as you read this, however, as telescopic vision extends ever backward in time and data is fed into powerful new computer models.

Evolving idea

Demonstrations of co-evolution began to emerge in the mid-1990s when researchers found hints that the existence of a significant black hole at the center of a galaxy was related to the galaxy's shape, says Martin Haehnelt of the University of Cambridge. Only galaxies with a spherical bulge-like component appear to accommodate supermassive black holes.

Our Milky Way, if it could be viewed edge on, would display a good example of one of these galactic bulges: Imagine the profile of a stereotypical flying saucer, though with a wider and flatter disk. The Milky Way is smaller than many galaxies, however, and it has a correspondingly less massive black hole -- roughly 2.6 million suns worth. It almost surely once had a quasar phase, astronomers say.

At any rate, in the mid-1990s no one knew for sure how prevalent black holes were. Theory and some observational data pointed to the likelihood that they were ubiquitous.

Then, in the year 2000, astronomers found solid evidence that black holes lurk deep inside many and probably all galaxies that have the classic central bulge of stars. Further, an analysis showed a direct correlation between the mass in each black hole and the shape and scope of the bulge and the overall size of the galaxy.

At an AAS meeting in June of 2000, John Kormendy of the University of Texas at Austin, presented evidence for 10 mammoth black holes whose masses were related to their galactic bulges. Kormendy worked on a large team of researchers led by University of Michigan astronomer Douglas Richstone. This along with other studies in surrounding months by other teams served as a collective turning point for co-evolution, several researchers now say, advancing it to a stable quantitative footing.

"Subsequently the idea of the co-evolution of galaxies and supermassive black holes became more widely discussed and accepted," Haehnelt says.

Evidence continues to mount. In 2001, two separate teams showed that many smaller galaxies that don't have bulges also do not seem to contain significant black holes.

Over the past six months or so, other important studies have emerged, providing independent confirmation to some of the initial work. Haehnelt: "It becomes more and more clear that supermassive black holes can significantly change the structure and evolution of galaxies."

The first large-scale scientific meeting devoted to co-evolution -- a sure sign of a theory coming into its own -- was held just three months ago, sponsored by the prestigious Carnegie Observatories.

There are many variations on the basic theory of co-evolution. Each version attempts to explain a vexing fact: In the blink of a cosmic eye -- just a half a billion years -- invisible spheres of matter were born, and several gained the mass of a billion or more suns and were driving the shape and texture of swirling agglomerations of newborn stars.

Co-evolution is not a done deal. Perhaps, some have suggested, a huge black hole simply collapses out of a pre-galactic cloud and serves as a ready-made engine to drive further galaxy development. Even staunch supporters of co-evolution say there are still viable theories, not yet refutable, putting the immense black hole in place first, and others that have the galaxy solely responsible for driving the formation of a black hole.

If black holes did grow incrementally, it is unclear whether cooperative construction reigned from the beginning, or if it kicked in after some certain amount of mass was gathered.

"I think it is still unclear whether black holes play any role in the formation of the first galaxies," said Cambridge's Sir Martin Rees, who has collaborated with Haehnelt and who long ago authored some of the first scientific papers on the question.

"Indeed," Sir Martin says, "there is a lot of debate about whether black holes can form in very small galaxies, and whether there is a link between the 'small' holes that form as the endpoint of the evolution of massive stars and the holes of above a million solar masses that exist in the centers of galaxies."

Another dark matter

Infusing itself into the equation is an utter unknown: dark matter. This as-yet-undetected stuff permeates all galaxies, researchers believe. A halo of it surrounds our Milky Way. Dark matter does not interact with light, but it does possess great gravitational prowess, acting as invisible glue to help hold galaxies together.

Dark matter is taken into account in the leading co-evolution models, but only in a general, overall sense. Some researchers, however, think dark matter, more than a black hole, is clearly connected to a galaxy's birth and development.

Just last week, the first possible direct evidence was announced for dark matter halos around early quasars. The finding, by Rennan Barkana of Tel Aviv University and Harvard astronomer Abraham Loeb, appears to be the first glimpse at the anatomy of the most distant quasars. Importantly, it supports the fundamental ideas of co-evolution, Loeb said. But it also makes it clear that dark matter will not be denied a chapter in any book about the theory.

Laura Ferrarese, a Rutgers University physicist, analyzed the new dark matter finding. She says it shows that a supermassive black hole, the stars around it, and an all-encompassing dark matter halo are working in concert to build structure.

This image is an artist's concept of a quasar's engine - a black hole pulling in surrounding gas and dust. In this image, the black hole is buried in the center of a disk of gas and dust (brown and yellow cloudy area in center). This material whirls around the black hole before plunging in, like water down a drain. This generates intense friction, heating the gas and causing it to shine brightly. CREDIT: Aurore Simonnet, Sonoma State University

Taken with other evidence, Ferrarese sees dark matter's role as more significant, or at least more obvious, than many theorists have considered.

"There is an observational correlation between the mass of the black hole and the mass of the dark matter halo, not necessarily the mass of the galaxy itself," she said.

Through this haze of fuzzy information and diverse thinking, theorists must work to explain a stark and staggering fact: Somewhere between 300 million and 800 million years after the Big Bang, the first black holes were born and managed to each gulp down a mass of more than 1 billion suns.

Now before you ponder how these Sumo wrestlers of the early universe must have thrown their weight around in any evolutionary wrestling match, consider this: A black hole typically holds much less than 1 percent of the overall mass of the galaxy it anchors.

Shining light on the dark ages

The early history of black holes -- what went on in the 500 million years leading up to objects observable with current technology -- is tied back to the development of the very first stars. Speculating about it requires first rewinding to the very beginning.

When the universe was born, there was nothing but hydrogen, helium and a little lithium. All this raced outward for about 300,000 years before anything significant happened. The gas was too compacted and therefore too hot to be stable. Gradually, the stuff of space expanded and cooled enough for gas to "recombine and stabilize to neutral states," as scientists put it.

The hydrogen was still too hot to form stars, so more expansion was needed. A long stretch of boring darkness ensued, during which some ripples began to ruffle the otherwise smooth fabric of space.

"For 300 million years, nothing happened," explains Windhorst, the Arizona State University astronomer. "The universe is just sitting there. Then all of a sudden the first stars began to shine."

The exact timing for first light is not known. But the ensuing 500 million years are the so-called dark ages of cosmology. Or more precisely, they represent the illuminations of the universe and the elimination of the dark ages.

"The tail end of that is what we're seeing," Windhorst says of the latest Hubble and Sloan survey observations.

The first black holes

Scientists once imagined galaxies forming by a sort of monolithic collapse, in which a giant cloud of gas suddenly fell inward. The modern view is one of "hierarchical merging," in which bits and pieces build up over time. A rough outline of how it all went down is fairly well agreed upon.

The initial ripples in space drew together into knots and filaments, locally and over broader scales. Individual clumps of gas collapsed, and stars were born.

The first stars must have been massive, perhaps 200 times the weight of our Sun or more. They would have been almost pure hydrogen -- the primary ingredient of thermonuclear fusion, which makes a star shine.

Massive stars are known to die young. Some survive just 10 million years (the Sun is 4.6 billion years old and just reaching middle-age). A colossal explosion occurs, sending newly forged, heavier elements into space. Remaining material collapses. A mass equal to many stars might end up in a ball no larger than a city. The result: a stellar black hole. These object are so dense that nothing, not even light, escapes once inside a sphere of influence known as an event horizon.

Stellar gravity wells can weigh as little as a few suns. But the inaugural versions might have been 100 times as massive as the Sun or more.

During all these tens and hundreds of millions of years, more stars are being born from the detritus of the first stars. Locally denser regions of gas contract. Stars form groups of perhaps a few dozen, which might be attracted to other star clusters. Eventually, clusters of many thousands of stars develop and began to look and behave like something that could be called a sub-galaxy. Some probably harbored growing black holes near their centers.

Here, theory struggles. Intuition might suggest that many of these huge stellar black holes simply merged until one central object attained enough mass to drive the shape and future development of its galaxy.

If that intuition is right, however, which black hole became the center?

"It may be a question of being in the right place at the right time," says Roger Blandford, a theoretical astrophysicist at Caltech. "It could be accidental."

In fact, nobody knows for sure if the first super-sized black holes developed from a series of mergers -- several dozen solar masses becomes 200, then 1,000, then 10,000, and so on -- or if they collapsed from the condensing gas cloud. "Do they start from 100 solar masses or a million solar masses? That's a good question," Blandford said. "My personal guess is that they start from a few hundred solar masses, but that's a much more speculative business."

Elusive middleweights

Galaxy birth and development is a never-ending process, and clues to early black hole evolution are spread throughout our own galaxy and around the universe. Astronomers therefore examine modern-day cosmic creatures for clues to their ancestral roots.

Black holes are everywhere, for one thing. Millions of the stellar sort could litter our galaxy alone, based on early discoveries of a few.

If the mightiest black holes indeed developed out of the garden variety, then there ought to be some evidence lying around our cosmic backyard in the form of middleweight versions, one line of thinking goes.

A handful of astronomers are convinced they have found a couple of these missing links, and in fact are arguing their case this week at a conference in California. But the case of the middleweights is among the most controversial in all of astronomy.

"The existence of middleweight black holes is one of the big unanswered questions in this field," said Cambridge's Haehnelt. "The recent claimed detections are still very controversial."

Regardless, most experts agree middleweights would represent, at best, pocket change to the fully grown black hole, something like Microsoft's initial millions in annual revenue compared to the billions that poured into its coffers during the tech boom.

Researchers on both sides of the middleweight argument mostly agree that the bulk of a jumbo black hole doesn't come through early mergers. Once a critical mass is achieved -- and this appears to coincide with a point in time prior to what astronomers can see today -- a black hole seems to gain most of its mass by swallowing gas from its environment.

Amid all the squabbling over middleweights looms the likelihood of much larger merger candidates.

Mega-mergers

Galaxy merging is almost a given. It is thought to have contributed significantly to the past growth of the Milky Way, for example. The early universe, having not yet expanded much, was incredibly crowded. Like racked billiard balls, nascent galaxies were more likely to collide.

If two galaxies merge, so should their black holes. Recent computer modeling speculates the event would be violent, unleashing tremendous light as gas is trapped between the two black holes and then rushes toward the more massive one.

Galactic mergers take millions of years, so they can't readily be observed in progress.

A recent peek into a nearby galaxy provided evidence for the scenario, however. At the heart of galaxy NGC 6240 astronomers found not one but two black holes, roughly 3,000 light-years apart and closing on an apparent merger course. The Chandra X-ray Observatory observations show that NGC 6240 is actually two galaxies that started joining forces about 30 million years ago.

Other indications of mega-mergers come from relatively nearby quasars.

Richard Larson, a Yale astronomer who studies star formation in galactic nuclei, says galaxies can go through several quasar phases during their lives. In studying quasars at more reasonable distances (which also means not so far in the past), he consistently sees signs of recent galaxy mergers or other large-scale interactions that served as triggers.

"Interactions and mergers are an excellent way to dump a lot of gas into the center of a galaxy," Larson explains. "The first thing this gas does is suddenly form huge numbers of stars."

Bursts of intense star formation seem to last about 10 million to 20 million years around a typical quasar.

Some of the gas that does not go into generating stars falls on in to the black hole. This violent phase of consumption is the one that is readily observed, because the castoff energy turns the incoming gas and dust into a glowing cloud. Eventually, the chaos settles and the new stars become visible. Later, the quasar itself is left naked. Finally, it goes dormant.

Larson figures this scenario for black hole feeding probably applies to the most distant quasars, too. And it supports the notion that black holes do in fact gain most of their bulk by accreting gas.

Fresh spin

To sort out the specifics of co-evolution, astronomers will need to see more of the universe and inspect it in greater detail. The prospects are good, especially toward the end of this decade.

A project called LISA (Laser Interferometer Space Antenna) would search for "gravitational waves" kicked up in the aftermath of black hole mergers, perhaps proving that such colossal collisions do occur. The NASA satellite is tentatively slated for launch in 2008.

A vastly improved understanding of dark matter is also needed. Several telescopes should contribute to this effort, but since no one knows what the stuff is, forecasting any sort of resolution is highly speculative.

And the specific mechanics of black holes must be investigated fully. For now, theorists don't even know exactly how matter is shuttled inward and consumed. Much of this work can be done by observing the nearby universe.

Roger Blandford, the Caltech theoretician, has suggested a novel way to prove that early mergers were not serious contributors to black hole growth. Blandford says two primary parameters characterize black holes. Mass is the most obvious. A more subtle measurement is spin.

Yes, black holes seem to spin. The idea only emerged from theory to relatively firm observations in May of 2001, and it remains unproven.

But if spin can be proved a universal aspect of black holes, then the rate of spin can be used to infer something very important about a black hole's history.

"If black holes grow by merging, by combinations of black holes, they should spin down quite quickly," Blandford explains. "This then becomes a fairly good argument that, if you can show that black holes really are spinning rapidly, they probably didn't grow by merging, but would have grown by accreting gas."

Most important, vision simply must be extended further back in time, beyond the quasars that are now being studied, says Karl Gebhardt, a University of Texas astronomer and a member of Richstone's team.

"They're essentially the tip of the iceberg," Gebhardt says of the objects so far observed. "We are projecting from what we see in a very special number of objects to the whole sample. That is part of the problem of the uncertainty now."

Hubble may extend current vision a bit, but the next boon in deep-space discovery will likely have to wait for the James Web Space Telescope, planned for launch in 2010. Billed as the "first-light machine," the JWST will be Hubble on steroids, and it should muscle its way to a better view of a good portion of the cosmic dark ages.

It is ironic to think that when JWST goes up, many astronomers and cosmologists will be banking on black holes to light the way to a scientific account of the earliest epoch of the visible universe, an obscure time they have long dreamed about and can now, almost, see.

Edited by Lazarus Long, 22 May 2003 - 11:31 PM.

http://www.nature.co...9/030609-7.html
Universe can surf the Big Rip
Alternative proposed to dark energy's cosmic doomsday.
11 June 2003
PHILIP BALL

The Big Rip is a break down of all the forces of nature.
© NASA

The end of the world is not so nigh. A Spanish scientist has found a loophole in the suggestion that there might be a Big Rip in the universe about 22 billion years from now1.

Earlier this year, US researchers showed how the recent discovery of an accelerating universe raises the possibility that in future everything may rend asunder, starting with clusters of galaxies and ending with the smallest of subatomic particles2.

Now Pedro González-Díaz of the Consejo Superior de Investigaciones Científicas in Madrid is arguing that, even if the universe is built the way Big Rip proponents suggest, a cosmic doomsday is not inevitable. The universe might just go on expanding, he says.

Given the timescales involved, we needn't start fretting too much either way. But there's no denying how terrible the Big Rip sounds. It is a kind of breakdown of all the fundamental forces of nature, as empty space becomes so full of energy that it overwhelms them. When that happens, everything falls apart.

Phantom menace

The destruction begins, say Robert Caldwell of Dartmouth College in New Hampshire, USA, and his coworkers2, about a billion years before it ultimately ends in a Big Rip. First, gravity loses its grip at cosmic scales, allowing clusters of galaxies to drift apart.

Sixty million years before doomsday, our own galaxy, the Milky Way, fractures as stars slip from each other's grasp. A few months before the end, planetary systems like the solar system will be dismembered, and 30 minutes before the Big Rip, the planets and stars themselves disintegrate.

In the split-second before the end, atoms and molecules are torn apart, then the particles that constitute them. Finally, space itself flies open.

All of this is driven, the argument goes, by something known as phantom energy, which fills all of space. The density of phantom energy increases with time, like a bomb that grows ever bigger.

Energy bar

No one knows if phantom energy exists at all. But recent astronomical observations hint that it might.

Five years ago, astronomers found that the universe is expanding at an ever-accelerating rate. The cosmic speed-up suggests that space is permeated by dark energy, creating a kind of pressure that opposes the pull of gravity.

One explanation for this dark energy reinstates the idea of a cosmological constant, which Albert Einstein first proposed and then rejected in the early twentieth century. According to this hypothesis, the universe will merely expand forever, with distant galaxies gradually winking out of sight.

An alternative possibility is that the dark energy takes the form of so-called phantom energy. This is more pathological than the dark energy supplied by a cosmological constant, Caldwell and colleagues say. They point out that phantom energy will become ever more dominant over other kinds of matter and energy as time progresses.

Or perhaps not. González-Díaz points out that some kinds of phantom energy can be well behaved, avoiding the blow-ups and instabilities that lead to a Big Rip.

Dark energy can be thought of as a kind of gas filling all of space, the density of which is proportional to its pressure. González-Díaz shows that if one assumes that this 'gas' has certain properties - specifically, that the speed an oscillation passes through it decreases with time - then there is no longer a Big Rip. This might sound contrived, but actually, González-Díaz reckons it is a more realistic kind of behaviour than the alternatives.

To settle the debate over what's in store for the Universe, astronomers will have to probe deeper into how it looked soon after the Big Bang, and how it is expanding now. Questions like this are being investigated by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite operated by NASA.


References
González-Díaz, P. F.You need not be afraid of phantom energy. Preprint, http://xxx.arxiv.org...stro-ph/0305559, (2003). |Article|
Caldwell, R. R., Kamionkowski, M. & Weinberg, N. N. Phantom energy and cosmic doomsday. Preprint, http://xxx.arxiv.org...stro-ph/0302506, (2003). |Article|


© Nature News Service / Macmillan Magazines Ltd 2003

I am posting this excerpt of this old article here and will post the link in another topic on Natural Spirituality that overlaps the discussion.

http://www.nature.co...2/020812-2.html

Is physics watching over us?
Our Universe is so unlikely that we must be missing something.
13 August 2002
PHILIP BALL
(excerpt)

An expanding universe is destined to repeat itself.
© Nasa

In an argument that would have gratified the ancient Greeks, physicists have claimed that the prevailing theoretical view of the Universe is logically flawed. Arranging the cosmos as we think it is arranged, say the team, would have required a miracle1.

An ever-more-rapidly expanding Universe is destined to repeat itself, say Leonard Susskind of Stanford University, California, and his colleagues. But the chances that such re-runs would produce worlds like ours are infinitesimal.

So either space is not accelerating for the reasons we think it is, or we have yet to discover some principle of physics, the researchers conclude. Like a guardian angel, this principle would pick out those few initial states that lead to a Universe like ours, and then guide cosmic evolution so that it really does unfold this way.

Whoa, Lazarus, slow down! With a million different cosmic mysteries to ponder in the same thread, we're likely to find this one very large unorganized mess, especially if people besides you post on it in reply to one of the topics you mentioned.

However, regarding clocks running slower or faster depending on their orientation. Oh, wow, what a sticky problem in special relativity. However, being that I'm working on devising an experiment right now to detect any casimir amplified Lorentz transformations due to the earth's absolute velocity with respect to cosmic background radiation (it's fair enough for our purposes to call it absolute velocity, as the cosmic background radiation is uniformly distributed throughout the universe). According to Einstein, space is isotropic. We shouldn't be able to detect anything with the body of our current capabilities, or at least at the levels of funding I have access to [:o] , as our observational equipment, including our bodies, are subject to the same Lorentz transformations as what we're observing...

And that doesn't even touch super-string theory.

As for doubly special relativity... my word, there is a LOT to keep track of in this field. And my four hours of sleep last night isn't helping either. Okay, I've been dinking around with the equation for more than the last hour, my eyeballs are about to fall out of my head, and all I've been able to figure out is that the equation makes all values of E equal to EsubP in magnitude, 1X10^19 (Joules), regardless of mass. It's boggling my overworked brain, especially after that bit about MWI I wrote last night.

As for implications, I'm not sure. For immortalists who intend to see the end of the universe (all your nanotechnology won't prevent you from being compressed into a singularity at the end of time), by far the more important focus is on immediate, short-term, and mid-term goals (by mid-term, I only mean 75-150 years or so). It's rather irrelevant how the universe ends if you're dead, right?

Maybe I AM tired.

Dark Energy Confirmed: Shadow of Mystery Force Seen in New Study
8 minutes ago Science - Space.com

"I awoke on Friday and because the universe is expanding it took me longer than usual to find my robe."
-- Woody Allen, in "Strung Out," the New Yorker, July 28, 2003

In a recent satiric article in the New Yorker magazine, Woody Allen makes a passing reference (a sexual one, of course) to dark energy. I suspect he knows -- though he does not say so -- that the universe is actually expanding at an accelerating pace, driven by this mysterious force.

So I figure Allen would be interested to know about a new study that provides important confirmation for the existence of dark energy, even if scientists remain baffled over what it is and how it works.

Whereas gravity attracts, dark energy repels (or sucks, depending on whether its viewed as an internal or external force relative to the universe). Theorists have no clue what's behind this antigravity, but they say it fuels an increased pace by which all galaxies in the universe recede from one another. The end result, as best as they can figure, is a lonely universe in which folks in one galaxy can no longer see or hear from the folks in other galaxies because they're moving away at the speed of light.

Or perhaps, one fantastic theory posits, the acceleration will ultimately shred all matter in a Big Rip.

Observations of dark energy have so far been very indirect, limited to examining the light from distant supernovae to determine the state of the expansion at the time the light left the exploded stars.

The new study employed an entirely different method. Researchers compared millions of galaxies imaged by the Sloan Digital Sky Survey with a temperature map of the early universe recently developed with data collected by NASA (news - web sites)'s Wilkinson Microwave Anisotropy Probe (WMAP).


Dark energy's shadow

The researchers say they found dark energy's shadow on the cosmic microwave background radiation, a relic of the earliest epoch of the universe after the Big Bang that supposedly started it all.

Let's back up: The theorists theorized about what would happen to the microwave radiation over time, if there was dark energy and if there was not.

They determined that dark energy should leave a certain imprint, and it did.

Photons streaming from the cosmic microwave background, across time, pass through many concentrations of galaxies and dark matter, explained study team member Andrew Connolly of the University of Pittsburgh. As the photons fall into a gravitational well created by a large cluster of galaxies, they gain energy -- just like a ball rolling down a hill. As they come out they lose energy.

Photographic images of the microwaves become more blue (i.e. more energetic) as they fall in toward a well and become more red, or less energetic, as they climb away.

"In a universe consisting mostly of normal matter one would expect that the net effect of the red and blue shifts would cancel," said Albert Stebbins of the Fermi National Accelerator Laboratory. "However in recent years we are finding that most of the stuff in our universe is abnormal in that it is gravitationally repulsive rather than gravitationally attractive."


Welcome new data

The research, announced last month, shows that "dark energy, whatever it is, is something that is not attracted by gravity even on the large scales probed by the Sloan Digital Sky Survey," said David Spergel, a Princeton University cosmologist and a member of the WMAP science team. "This is an important hint for physicists trying to understand the mysterious dark energy."

John Blakeslee of Johns Hopkins University recently led a separate study of two very distant supernovae that helped pin down the timing of a switch from deceleration to acceleration in the universe, which occurred about 6.3 billion years ago. (Yes, the universe has always been expanding, but not always at an accelerating rate.)

Blakeslee told SPACE.com the Sloan result "provides an important consistency check" for assumptions about dark energy.

But are we sure now that dark energy exists as it has been described? "There still is some room for doubt," Blakeslee said.

If dark energy baffles the smartest scientists -- and it does -- then the rest of us can be excused for wondering what all this means to the evolution and fate of the universe. We can even be excused for not comprehending any of this. Woody Allen claims his grasp of general relativity and quantum mechanics "now equals Einstein's -- Einstein Moomjy, that is, the rug seller."

And Moomjy knows the source of dark energy just about as well as anyone.

All About Dark Energy
Space Myths, Mysteries & Hoaxes
Space Mailbag

Whoa, Lazarus, slow down! With a million different cosmic mysteries to ponder in the same thread, we're likely to find this one very large unorganized mess, especially if people besides you post on it in reply to one of the topics you mentioned.

However, regarding clocks running slower or faster depending on their orientation. Oh, wow, what a sticky problem in special relativity. However, being that I'm working on devising an experiment right now to detect any casimir amplified Lorentz transformations due to the earth's absolute velocity with respect to cosmic background radiation (it's fair enough for our purposes to call it absolute velocity, as the cosmic background radiation is uniformly distributed throughout the universe). According to Einstein, space is isotropic. We shouldn't be able to detect anything with the body of our current capabilities, or at least at the levels of funding I have access to  , as our observational equipment, including our bodies, are subject to the same Lorentz transformations as what we're observing...

Then you will love the recent map generated from the new orbital gravity sensor GRACE Mission that shows that Earth gravity is no where near uniform along its surface. I know the variations will be minute, to undetectable between various regions but if there is a relationship between the strength of gravity's acceleration and the actual rate of time's meter then even on the Earth's surface there will be slight yet real variations in the flow of time. This could account for recent discoveries as to differences in the Atomic Clock and weights and measures that showed up when comparing expected measures after nearly a century.

http://news.bbc.co.u...ech/3093927.stm

'Potato' Earth's deep secrets

By Jonathan Amos
BBC News Online science staff

It is a map the like of which you have probably never seen before.


Gravity highs are marked red; gravity lows are blue

The sweep of colours shows minute variations in the Earth's gravitational field.

If you were to fly over the red areas, you would be tugged ever so slightly downwards; the blues mark regions where the planet's attraction is much weaker.


Sharp focus

The map has been produced by the US-German Gravity Recovery and Climate Experiment (Grace) mission.

This model is the first full science product to come out of the mission which gathers its data from two spacecraft orbiting more than 450 kilometres above the Earth.

The Grace twins, which were launched last year, are still being tested but already their gravity map easily surpasses the detail of any other previously obtained.

(reference article for full text and links)

http://story.news.ya...onpushesforward

Gewis adds:

As for implications, I'm not sure. For immortalists who intend to see the end of the universe (all your nanotechnology won't prevent you from being compressed into a singularity at the end of time), by far the more important focus is on immediate, short-term, and mid-term goals (by mid-term, I only mean 75-150 years or so). It's rather irrelevant how the universe ends if you're dead, right?

All I am trying to establish is that there is a lot more we don't know than we do by these articles but if the recent data about Dark Energy and separately Dark Matter turns out to be accurate then the Universe may not die by compression into a Singularity after all. Hence we return to the infinite future problem, Cold Death and/or the Big Rip scenarios, or some alternative as yet undeveloped.

I am not even tired and this stuff makes my head spin. I like Cosmology and physics but I agree pragmatically that our general focus should be on first surviving the coming years and extending the organic and trans-organic possibilities for longevity that extend transhuman lifespans to first centuries and then millennium. I think then we can worry about surviving epochs. )

I am going to post this free book review from Nature in full because it raises issues that have been addressed in a number of the topics in physics here in this forum, from talking abut Lynd's work to Dark Matter/Energy relationships. The book should be of interest to all of us concerned with physics and Cosmology.

The short commentary is most helpful in phrasing what we know we don't know in concise language that allows a careful student to understand why some of us are sticking to our guns demanding more open discussion on radical theory regarding a definition of the Universe and all that entails.
LL/kxs

http://www.nature.co...425239a_fs.html
Cosmological questions
Nature 425, 239 (18 September 2003); doi:10.1038/425239a
MARTIN REES

Martin Rees is at the Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK.

Can 'big science' shed light on dark matter and the nature of the cosmos?

Connecting Quarks With the Cosmos: Eleven Science Questions for the New Century by the Committee on the Physics of the Universe, National Research Council of the National Academies

National Academies Press: 2003. 222 pp. $39, £27.95

LAWRENCE BERKELEY NATIONAL LAB.

Looking for clues: the Sudbury Neutrino Observatory in Canada provides insight into the nature of the Universe.

Astronomers have traditionally been 'users' of physics, but now they are returning the compliment. They can discover new physics by probing much more extreme conditions than could ever be produced in Earth-bound laboratories: neutron stars and supernovae reach exceedingly high densities and temperatures, and cosmic rays have millions of times more energy than can be achieved in the biggest terrestrial accelerator. There are growing links between the sciences of the very large and the very small — between cosmos and microworld. Exhilarating progress has already been made: recent advances in cosmology will provide an epochal chapter when the history of science in this decade is written.

Connecting Quarks With the Cosmos was written by a panel of experts, chaired by Michael Turner of Chicago University, who were charged with assessing the key challenges and opportunities at these scientific interfaces. They winnowed the list down to 11 key questions, and offered some recommendations about how to address them.

Heading the list of questions is: "What is dark matter?" Galaxies and clusters of galaxies would fly apart were they not held together by the gravitational pull of dark matter, which contributes five times more mass than the ordinary atoms that make up all the stars, planets and gas.

Dark matter consists of electrically neutral particles that have survived from the hot early Universe. Identifying these particles would not only clarify what the Universe consists of, but also reveal a new type of particle. The importance of searching for such particles provides an impetus for the further development of the underground laboratories. Underground measurements of neutrinos from the Sun have already led to one of the most important discoveries in particle physics of the past 20 years — that neutrinos have a mass greater than zero.

The favouritism for matter over antimatter in the Universe could only have come about if baryon number — the number of quarks minus the number of antiquarks — were not absolutely constant. The downside of this non-conservation of baryon number is that protons can decay. (The instability of protons is another of the key questions considered.) This incredibly slow process — maybe one decay per year in a thousand-ton tank — is another candidate for an experiment in an underground laboratory.

In the past few years an even more baffling mystery has emerged: 70% of the cosmic mass-energy seems to be neither in atoms nor in dark matter, but latent as 'dark energy' in empty space. Associated with this energy is a negative pressure; according to Einstein, this then exerts an 'antigravity', causing cosmic acceleration. The nature of the dark energy — another of the questions tackled in this book — can be pinned down by more careful measurements of the relationship between redshift and distance, a task that requires telescopes that can detect large numbers of distant supernovae.

Another question is: "Did Einstein have the last word on gravity?" Einstein has been impressively vindicated by high-precision tests within the Solar System, by gravitational lensing and by pulsar studies. These tests, however, pertain to the 'weak field' limit, where Einstein's theory only slightly modifies Newton's.

Einstein predicted that black holes should be standardized objects, characterized by just two numbers — mass and spin — and described precisely by equations first described by Roy Kerr, but we have no direct evidence that this is so. To test strong gravity, we need to detect (and model) gravitational waves from black holes crashing together, and study the radiation from gas swirling in the strong-field region, or energy extracted from the spinning hole itself. We know that Einstein's theory is transcended deep inside black holes, and also at the beginning of the Universe, where conditions are far more extreme than any extrapolation of physics that we can test.

Are there extra spatial dimensions beyond the three that we are familiar with? According to string theory, ten dimensions may have played a role in the ultra-early Universe — but if so, why did only three expand? Cosmological observations, particularly of the microwave background radiation, may offer clues.

Perhaps new physics is needed not only where space-time curvature is large, but when particles move very fast. The best probes for such an effect would be the most energetic cosmic rays, whose speed differs from that of light by just 1 part in 1022. The Auger array in Argentina, now under construction, should be able to collect enough date to settle some issues that have been tantalizingly uncertain for several years.

The focus of this book is 'big science' — spacecraft, accelerators and telescopes. But it is gratifying that some fundamental questions can still be tackled with tabletop experiments. For instance, ingeniously designed torsion balances can test the gravitational inverse square law on scales of less than a millimetre, constraining the scale on which extra spatial dimensions could be wrapped up.

The book reflects an admirable feature of the organization of big science in the United States. Long-term priorities are set by panels whose members are selected for scientific distinction and balance, and who engage in wide and open consultation. Such consultation has value in itself, broadening the perspective of individual researchers, and forging a firm consensus. Set up by the National Academies, the panels operate at arm's length from funding agencies, such as the National Science Foundation, NASA and the Department of Energy. Even so, their reports are taken very seriously by the funding agencies and by the congressional committees that sanction individual projects.

Given its collective authorship, one would expect this book to be authoritative, and it is, but it is also attractively readable. That such an excellent book can come from a committee testifies to the intellectual thoroughness with which US priorities in big science are optimized.

it will take me forever to read this

it will take me forever to read this

Take your time and digest it...

Or do you mean that as a bad thing? )

Another theory on the shape and extent of the universe:

Read the full story at Newscientist

 
Big Bang glow hints at funnel-shaped Universe

19:00 14 April 04
 
Exclusive from New Scientist Print Edition. Subscribe and get 4 free issues.
 
Could the Universe be shaped like a medieval horn? It may sound like a surrealist's dream, but according to Frank Steiner at the University of Ulm in Germany, recent observations hint that the cosmos is stretched out into a long funnel, with a narrow tube at one end flaring out into a bell. It would also mean that space is finite.

Adopting such an apparently outlandish model could explain two puzzling observations. The first is the pattern of hot and cold spots in the cosmic microwave background radiation, which shows what the Universe looked like just 380,000 years after the Big Bang.

It was charted in detail in 2003 by NASA's Wilkinson Microwave Anisotropy Probe. WMAP found that the pattern fades on the largest scales: there are no clear hot or cold blobs more than about 60 degrees across.

 
The shape of the cosmos
Steiner and his group claim that a finite, horn-shaped Universe fits this observation. It simply does not have room to hold very big blobs.

The present-day volume of their model universe is nearly 1032 cubic light years. Back when the Universe was only 380,000 years old it would have been a fraction of that size, too small to allow big fluctuations.


Infinitely long


In the model, technically called a Picard topology, the Universe curves in a strange way. One end is infinitely long, but so narrow that it has a finite volume. At the other end, the horn flares out, but not for ever - if you could fly towards the flared end in a spaceship, at some point you would find yourself flying back in on the other side of the horn (see diagram).

Horn-shaped models were suggested in the 1990s to fit a similar anomaly seen by the COBE satellite, but Steiner's group is the first to show that this idea fits the WMAP data. In 2003, another group claimed that the Universe might be finite (New Scientist, 8 October 2003.)

In this group's model, space had a soccer ball-like shape. But the model has run into trouble. It should have left a clear signature on the microwave sky - a set of circles that mirror each other's spot patterns - but these circles do not seem to be there.

The horn universe is harder to pin down. It would also make matching circles, but the pattern depends on what part of the horn we are in. "Our published search for matching circles probably does not rule out the Picard topology," says Neil Cornish of Montana State University in Bozeman.


Little ellipses


And the idea has another advantage. In the flat space of conventional cosmology, the smallest blobs on microwave sky maps ought to be round. But they are not. "If you look at the small structures, they look like little ellipses," says Steiner. The curve of the horn-shaped universe could be just right to explain this. If you look at any little piece of the horn, it is saddle-shaped like a Pringles potato chip - curving down in one direction and up in the perpendicular one. This "negatively curved" space would act like a warped lens, distorting the image of round primordial blobs in a way that makes them look elliptical to us. Mathematicians can construct an infinite number of different kinds of negatively curved space, most of them with one or more horns, and many of which might fit the data, but the Picard topology is one of the simplest.

This model would force scientists to abandon the "cosmological principle", the idea that all parts of the cosmos are roughly the same. "If one happens to find oneself a long way up the narrow end of the horn, things indeed look very strange, with two very small dimensions," says Holger Then, a member of the team.

I could put this in a half dozen different threads here but let's leave it here for the moment as it may not be a paradoxical mystery much longer if it turns out to be true.


http://www.newscient...p?id=ns99996151

Hawking cracks black hole paradox
19:00 14 July 04

After nearly 30 years of arguing that a black hole destroys everything that falls into it, Stephen Hawking is saying he was wrong. It seems that black holes may after all allow information within them to escape. Hawking will present his latest finding at a conference in Ireland next week.

The about-turn might cost Hawking, a physicist at the University of Cambridge, an encyclopaedia because of a bet he made in 1997. More importantly, it might solve one of the long-standing puzzles in modern physics, known as the black hole information paradox.

It was Hawking's own work that created the paradox. In 1976, he calculated that once a black hole forms, it starts losing mass by radiating energy. This "Hawking radiation" contains no information about the matter inside the black hole and once the black hole evaporates, all information is lost.

But this conflicts with the laws of quantum physics, which say that such information can never be completely wiped out. Hawking's argument was that the intense gravitational fields of black holes somehow unravel the laws of quantum physics.

Other physicists have tried to chip away at this paradox. Earlier in 2004, Samir Mathur of Ohio State University in Columbus and his colleagues showed that if a black hole is modelled according to string theory - in which the universe is made of tiny, vibrating strings rather than point-like particles - then the black hole becomes a giant tangle of strings. And the Hawking radiation emitted by this "fuzzball" does contain information about the insides of a black hole (New Scientist print edition, 13 March).


Big reputation

Now, it seems that Hawking too has an answer to the conundrum and the physics community is abuzz with the news. Hawking requested at the last minute that he be allowed to present his findings at the 17th International Conference on General Relativity and Gravitation in Dublin, Ireland.

"He sent a note saying 'I have solved the black hole information paradox and I want to talk about it'," says Curt Cutler, a physicist at the Albert Einstein Institute in Golm, Germany, who is chairing the conference's scientific committee. "I haven't seen a preprint [of the paper]. To be quite honest, I went on Hawking's reputation."

Though Hawking has not yet revealed the detailed maths behind his finding, sketchy details have emerged from a seminar Hawking gave at Cambridge. According to Cambridge colleague Gary Gibbons, an expert on the physics of black holes who was at the seminar, Hawking's black holes, unlike classic black holes, do not have a well-defined event horizon that hides everything within them from the outside world.

In essence, his new black holes now never quite become the kind that gobble up everything. Instead, they keep emitting radiation for a long time, and eventually open up to reveal the information within. "It's possible that what he presented in the seminar is a solution," says Gibbons. "But I think you have to say the jury is still out."


Forever hidden

At the conference, Hawking will have an hour on 21 July to make his case. If he succeeds, then, ironically, he will lose a bet that he and theoretical physicist Kip Thorne of the California Institute of Technology (Caltech) in Pasadena made with John Preskill, also of Caltech.

They argued that "information swallowed by a black hole is forever hidden, and can never be revealed".

"Since Stephen has changed his view and now believes that black holes do not destroy information, I expect him [and Kip] to concede the bet," Preskill told New Scientist. The duo are expected to present Preskill with an encyclopaedia of his choice "from which information can be recovered at will".


Jenny Hogan