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Faded Stars Show Universe Is 14 Billion Years Old

graham

Well-Known TRIBEr
WASHINGTON (Reuters) - The dimmest, most faded old stars, glimpsed by the Hubble Space Telescope (news - web sites), offered confirmation that the universe is just under 14 billion years of age, scientists said on Wednesday.

That is an estimate, scientists at NASA (news - web sites) headquarters told reporters, with an error margin of 500 million years either way.

But because it was calculated by a completely different method than earlier estimates, it offers independent verification that astronomers are on the right track.

"It's almost as if we were saying, you always thought you knew how old you were, but you never had proof," Bruce Margon of the Space Telescope Science Institute explained. "One day, you open a drawer and there's your birth certificate, and you get the same answer. That's a real triumph."

To get this confirmation, astronomers aimed the orbiting Hubble telescope at a globular cluster of stars in the constellation Scorpio, some 7,000 light-years from Earth. A light-year is the distance light travels in a year, about 6 trillion miles (10 trillion km).

Such clusters are thought to be the oldest structures in the universe, coming into being about a billion years after the theoretical big bang.

Within these clusters are scores of so-called white dwarfs, burned-out stars that have spent all the nuclear fuel at their cores and are simply fading slowly into darkness.

"They're about the most boring stars you can think of, they're just cinders cooling off," Margon said. "It's just the glowing ember of a fire that is gradually cooling down at a predictable rate."

That predictable cooling rate is the key to calculating the age of the universe, Margon and other astronomers said. Since they knew how fast these old stars were cooling, they could figure how old they were by how bright they were.

That number turned out to be just under 13 billion years; the astronomers -- led by Harvey Richer of the University of British Columbia in Vancouver, Canada -- added 1 billion years to account for the billion years that they believe had elapsed before the globular cluster formed, and got their universe age estimate.

PREVIOUS ESTIMATES

Previously, scientists had calculated the age of the universe by measuring how fast galaxies were speeding away from each other as the universe grew. Many scientists have long believed that the universe is expanding at a predictable rate, but there was disagreement over just what this rate was.

In 1997, the Hubble telescope gave a precise measurement for the expansion rate, and a reliable age for the universe of around 15 billion years.

This estimate got complicated in recent years when astronomers using Hubble and other observatories encountered a strange force they called dark energy, which was making the universe expand more rapidly.

With dark energy factored into the equation, astronomers put the universe's age at 13 billion to 14 billion years -- in the same cosmic ballpark as the figure reached by tracking the fading out of the oldest stars.



The dimmest, most faded old stars, glimpsed by the Hubble Space Telescope, offered confirmation that the universe is just under 14 billion years of age, scientists said on April 24, 2002. In the top panel, a ground-based observatory snapped panoramic view of the entire cluster, which contains several hundred thousand stars. The box at left indicates the region observed by the Hubble telescope. The Hubble telescope studied a small region of the cluster. A section of that region is seen in the picture at bottom left. A sampling of an even smaller region is shown at bottom right. This region is only about one light-year across. In this smaller region, Hubble pinpointed a number of faint white dwarfs. The blue circles pinpoint the dwarfs. It took nearly eight days of exposure time over a 67-day period to find these extremely faint stars. (Nasa/Reuters)
 

Subsonic Chronic

TRIBE Member
Think of the jam we're gonna have when the Universe finally turns 14 billion years old!

tonight... we're gonna party like it's 13,999,999,999!

Pete :)
 

Stan

TRIBE Member
Gravastars Vie to Replace Black Holes, in Theory

Thick-Skinned Gravastars Vie to Replace Black Holes, in Theory (originally taken from http://www.space.com)

By Robert Roy Britt

As if black holes weren't mind-bending enough, a new hypothesis suggests an entirely new idea for Nature's densest objects. In fact, the idea goes black holes aren't holes at all but black bubbles with very thick skins.



The new idea, presented this week at a meeting of the American Physical Society, was conceived to provide an alternative to the exotic description of where stuff goes when a star collapses and becomes, in present theory, a black hole.

For most of us, the matter of where the matter goes is no less mysterious under the new notion.

Emil Mottola of the Los Alamos National Laboratory and Pawel Mazur of the University of South Carolina suggest that instead of a star collapsing into a pinpoint of space with virtually infinite gravity, its matter is transformed into a spherical void surrounded by "an extremely durable form of matter never before experienced on Earth."

The researchers call the objects gravastars. And, as with a black hole, you wouldn't want to get to close.

"Since this new form of matter is very durable, but somewhat flexible, like a bubble, anything that became trapped by its intense gravity and smashed into it would be obliterated and then assimilated into the shell of the gravastar," Mottola said.

There is no proof that this new form of matter exists, and thus gravastars remain for the moment no more than a potentially convenient proposal. But other astronomers are intrigued, both because black holes themselves remain mere theory, not fact, and because gravastars might explain strange physical observations that black holes don't.

Losing their grip

Black holes were conceived during World War 1 by the German astronomer Karl Schwarzschild, who while serving in the war was scratching solutions to Einstein's theories.

Black holes are theorized to be so dense that nothing, not even light, escapes the gravitational grip. Einstein first thought the idea was nuts. In a way, though, the concept is not as odd as one might think. Astronomers have clearly seen how any large object, such as the Sun or another star bends light and sends it on a new course. Black holes just bend light a whole lot more, folding its photons right into the object, Schwarzschild proposed.

Such excruciating bends cause the warping of both space and time, or space-time, as the theorists put it. Gravastars would be no less forgiving of what we traditionally call reality.

Inside a gravastar, space-time would be "totally warped," the researchers say. Further, the inner space would exert an outward force, which would enhance the durability of the bubble.

Mottola and Mazur have not worked out all the details of how gravastars might form. Yet they say the objects solve a flaw in black hole theory.

Physicists have long struggled to account for the tremendous entropy, or information, that a black hole would harbor. Theory holds that a black hole should have a billion, billion times more entropy sometimes referred to as states, than the star it formed from.

"Where are all these zillions of states hiding in a black hole?" Mottola said in a recent article in New Scientist magazine. "It is quite literally incomprehensible."

Gravastars don't have the same problem, as their entropy is said to be very low.

Remarkable properties

From the outside, a gravastar would appear much like a black hole; visible only by the high-energy emissions it spits from its jowls while consuming matter. Astronomers use X-ray observations, created by such cosmically carnivorous activity, to detect black holes. By noting the small region of space that can't be seen within a sphere inside those emissions, and by looking at the gravitational effects that the space has on surrounding matter, the black hole is deduced.

But inside, the material in a gravastar would have undergone a phase change, something like when water freezes to the solid state. The newly conceived, wildly dense phase of matter is theoretically rooted in a recent discovery.

In 1995, researchers cooled matter to near absolute zero and created a new form of matter called a Bose-Einstein condensate, in which the motion of electrons, protons, and everything else comes to a complete halt. Everything reaches a single state, called a quantum state, creating what's been called a "super atom."

The matter inside a gravastar would be akin to the Bose-Einstein condensate. It would exist in a vacuum, surrounded by an ultra-thin, ultra-cold, ultra-dark bubble, hence the name gra (vitational) va (cuum) star, or gravastar.

The "unique and remarkable properties" of a gravastar "could explain several high-energy astrophysical phenomena that now are puzzling," says Marek Abramowicz, a black hole expert at Gothenburg University.

Abramowicz thinks the violent creation of a gravastar might explain gamma ray bursts, distant explosions of incredible energy that puzzle researchers.

But Neil Cornish, an astrophysicist at the University of Montana, wonders whether an exploding star could shed enough entropy to become a gravastar. "I don't think that is a likely scenario," he told New Scientist.

Other theorists have criticized the gravastar hypothesis. Mottola and Mazur defend it but admit they have work to do before they can explain how the objects actually develop when a star collapses.

Yet even before they've figured this out, Mottola and Mazur have taken their extreme idea to a mentally dizzying new level: They say our entire universe may be the interior of a giant gravastar.
 

Locke

TRIBE Member
That gravastar stuff is pretty neat-o. Kudos to those scietists for putting fwd the theory...
I for one like it, what happens when matter gets so dense... subatomic particles have nowhere to go hence they are stationary kinda like the Bose-Einstein condensate.
I love new quantum cosmological thories, bends my mind.

On another note we might now know how long it took for earth to form
- universe ~ 15 billion years old
- earth ~ 3.4 - 4.5 billon yrs. old

BILLIONS PEOPLE, BILLIONS. and to think some people don't belive in evolution sheeesh! :)
 
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kurtz

TRIBE Member
Originally posted by Locke
On another note we might now know how long it took for earth to form
- universe ~ 15 billion years old
- earth ~ 3.4 - 4.5 billon yrs. old

BILLIONS PEOPLE, BILLIONS. and to think some people don't belive in evolution sheeesh! :)
*In full english-prof accent*
But where is the uncaused cause?? :D
 

G-FrEsH

TRIBE Promoter
Originally posted by Subsonic Chronic
Think of the jam we're gonna have when the Universe finally turns 14 billion years old!

tonight... we're gonna party like it's 13,999,999,999!

Pete :)
That is soo 1972...
what that means i dunno....

DAve...
 

G-FrEsH

TRIBE Promoter
Originally posted by kurtz
*In full english-prof accent*
But where is the uncaused cause?? :D
Dude you gotta watch the discovery channel..
they talk about this all the time.
They actually estimated along time ago that the earth was close to 10 not 14. But the scientist ran into sum problems involvin comets and Metero's being older then space. Then the scientist estimated around 14 to 15...
I learn more on Discovery then i ever did of 4.5 years of highskool.

DAve......
 
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Gavin the Bass

TRIBE Member
Big bang or cosmic crunch?


Reuters News Agency


Washington — What if the big-bang theory is wrong? What if the universe never began and will never end, driven forever to expand in a series of monster explosions and contract every eon or so in a cosmic crunch?

Princeton University physicist Paul Steinhardt suggested just that in a report published Thursday that even he called "mind-bending."

The big-bang theory, accepted by many scientists for decades, holds that the universe was born some 14 billion years ago when an unimaginably small, dense entity blew up, sowing the seeds of every bit of matter and energy.

Soon after that first explosion, it says, the universe expanded rapidly, in a phenomenon astronomers call inflation, and then continued to spread out at varying speeds until the present day. Under the theory, time would begin but never end.

But the model of the universe envisioned by Dr. Steinhardt and Neil Turok of Cambridge in the journal Science sees the big bang as merely a turning point on an infinite road: an endless series of big bangs make the universe expand and an equally endless series of subsequent crunches make it contract.

The current estimated age of the universe according to the big-bang theory would seem like the blink of an eye under the cyclic universe theory, which assumes the universe waxes and wanes in cycles lasting as long as trillions of years.

"Time does not have to have a beginning," Steinhardt said in a telephone interview. He said that what scientists theorize as the dawn of time might, in fact, be "only a transition or a stage of evolution from a pre-existing phase to the present expanding phase."

Scientists who favour the big-bang model see the expansion of the universe as governed by the amount and kinds of energy that comprise it. If the energy is the kind earthlings know — gravitationally self-attractive energy that clumps into galaxies, stars and planets and also makes a set of keys fall off a table — it tends to slow down the expansion.

But if it is a mysterious kind of gravitationally self-repulsive energy, known as dark energy, that would tend to speed expansion up.

Astronomers and others who ponder this question have been at pains in recent years to explain why the universe's expansion has been accelerating over the last several billion years after a long slowdown.

Dark energy's strange ways could be responsible.

"We can see, both directly and indirectly, that most of the stuff in the universe is not composed of ordinary matter, nor of dark matter, but of some third species," he said. "And we can see that the ratio is roughly 70:30 — 70 per cent exotic stuff, 30 per cent ordinary stuff."

What Dr. Steinhardt calls ordinary stuff is what allows the slower expansion of the universe, which permits gravity to create galaxies, stars and planets, including Earth. The accelerated expansion driven by dark energy would blow all that away before it could coalesce.

"This stuff, once it takes over the universe, it pushes everything away at an accelerating pace," he said. "So the universe will double in size every 14 to 15 billion years so long as there is this gravitationally self-repulsive energy that dominates the universe."

The big crunch comes when dark energy changes its character, according to Dr. Steinhardt. He likened it to a ball rolling down a hill that picks up speed as it goes along.

"This field of dark energy is picking up more and more energy as it rolls down the hill, the nature of the force that controls it causes it to rebound and go back to where it started, back and forth in a very irregular fashion," he said.

"When it's changing slowly, it's gravitationally self-repulsive and when it's changing fast, it picks up speed, it's gravitationally self-attractive," Dr. Steinhardt said.

Dr. Steinhardt admitted this made dark energy sound capricious.

"It is capricious but it's no more capricious than the standard picture," he said. "It's just different."
 

InFa

TRIBE Member
^
I've read that this theory is called the sustainable universe theory, however. I've also read that it defies the second law of thermodynamics which as I understand deals with entropy... over time entropy is constantly increasing because that's the direction energy flows in the real world -- toward diffusion. In other words things would be very chaotic by now and our 'odered' universe would pretty much be destroyed (if it is a closed system)... ie energy not created or destroyed... basically if no one was there to clean up your house it would eventually decay into a state of total chaos.

Ideas?

drew.
 
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