universe

The Universe comprises everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term Universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world or Nature.
Current interpretations of astronomical observations indicate that the age of the Universe is 13.73 (± 0.12) billion years,[1] and that the diameter of the observable Universe is at least 93 billion light years, or 8.80 × 1026 metres. (It may seem paradoxical that two galaxies on opposite sides can be separated by 93 billion light years after only 13 billion years, since special relativity states that matter cannot be accelerated to exceed the speed of light in a localized region of space-time. However, according to general relativity, space can expand with no intrinsic limit on its rate; thus, two galaxies can separate more quickly than the speed of light if the space between them grows.) It is uncertain whether the size of the Universe is finite or infinite.
According to the prevailing scientific model of the Universe, known as the Big Bang, the Universe expanded from an extremely hot, dense phase called the Planck epoch, in which all the matter and energy of the observable Universe was concentrated. Since the Planck epoch, the Universe has been expanding to its present form, possibly with a brief period (less than 10−32 seconds) of cosmic inflation. Several independent experimental measurements support this theoretical expansion and, more generally, the Big Bang theory. Recent observations indicate that this expansion is accelerating because of the dark energy, and that most of the matter and energy in the Universe is fundamentally different from that observed on Earth and not directly observable. The imprecision of current observations has hindered predictions of the ultimate fate of the Universe.
Experiments and observations suggest that the Universe has been governed by the same physical laws and constants throughout its extent and history. The dominant force at cosmological distances is gravity, and general relativity is currently the most accurate theory of gravitation. The remaining three fundamental forces and all the known particles on which they act are described by the Standard Model. The Universe has at least three dimensions of space and one of time, although extremely small additional dimensions cannot be ruled out experimentally. Spacetime appears to be smooth and simply connected, and space has very small mean curvature, so that Euclidean geometry is accurate on the average throughout the Universe. Conversely, on a quantum scale spacetime is highly turbulent.
The word Universe is usually defined as encompassing everything. However, using an alternate definition, some have speculated that this "Universe" is just one of many disconnected "universes", which are collectively denoted as the multiverse. For example, in Bubble universe theory, there are an infinite variety of "universes", each with different physical constants. Similarly, in the many-worlds hypothesis, new "universes" are spawned with every quantum measurement. These universes are usually thought to be completely disconnected from our own and therefore impossible to detect experimentally.
Throughout recorded history, several cosmologies and cosmogonies have been proposed to account for observations of the Universe. The earliest quantitative geocentric models were developed by the ancient Greeks, who proposed that the Universe possesses infinite space and has existed eternally, but contains a single set of concentric spheres of finite size – corresponding to the fixed stars, the Sun and various planets – rotating about a spherical but unmoving Earth. Over the centuries, more precise observations and improved theories of gravity led to Copernicus' heliocentric model and the Newtonian model of the Solar System, respectively. Further improvements in astronomy led to the characterization of the Milky Way, and the discovery of other galaxies and the microwave background radiation; careful studies of the distribution of these galaxies and their spectral lines have led to much of modern cosmology.

Infrared could shed light on secrets of cosmos

Infrared could shed light on secrets of cosmos
Stephen Cauchi
July 12, 2009

CALL it the space telescope with night-vision goggles. Nearly 20 years after the Hubble Space Telescope offered the first crystal-clear views of the cosmos, the Herschel Space Observatory is set to lift the veil on parts of the universe that are, even to the Hubble, invisible.

For Herschel is an infrared telescope — it observes heat, in the form of infrared radiation, rather than light. Active infrared night vision works on the same principle. Astronomers, as it turns out, enjoy being able to see in the dark as much as soldiers.

"I think there will be some spectacular images that will excite the public," said Chris Fluke, of Swinburne University's Centre for Astrophysics. "Even the test image that came through, of a galaxy, is a spectacular image in its own right. What we're seeing for the first time is clouds of cold gas sitting in the galaxy."

Herschel — which was successfully launched on May 14 — is different from Hubble in other respects as well. It's a much bigger telescope, with a mirror 3.5 metres wide compared to Hubble's 2.4 metres. Hubble is primarily a NASA project; Herschel is the work of the European Space Agency. Hubble orbits the Earth; Herschel orbits the sun and is 1.5 million kilometres from Earth, to avoid contamination from ground-based infrared radiation. The telescope is en route to this final orbit and will reach it later this month.

And Herschel will be kept cold — very cold. The irony of infrared astronomy is that even though it is based on detecting heat, it is most useful for observing cold objects. Clouds of gas and dust that are invisible to Hubble can be detected by Herschel because they emit heat at infrared wavelengths — even if that heat is hundreds of degrees below zero.

Andrew Hopkins, of the Anglo-Australian Observatory, said Herschel would be kept at minus 272 degrees below zero — only 1.4 degrees above absolute zero, the coldest possible temperature.

"Observations at (infrared) wavelengths require detectors to be kept exceptionally cold," said Dr Hopkins. "Even in an Earth orbit, the heat from the Earth would warm Herschel's detectors too much."

Dr Fluke said Herschel's primary mission would be to uncover one of the universe's great mysteries — how galaxies began to form after the Big Bang. "There are lots of unanswered questions on how galaxies form and evolve, and I think that's the big thing that Herschel's going to look at. Every time we've put up a new telescope — whether on the ground or in space — we need to keep changing our view on this. That's the biggest question in galactic astronomy at the moment."

Herschel, like Hubble, is powerful enough to see back in time to the evolution of the first galaxies, which occurred within a billion years of the 13.7 billion-year-old Big Bang. The even bigger James Webb Space Telescope, due for launch in 2013, will allow astronomers to see back to the evolution of the first stars, which predated galaxy formation.

Dr Fluke said the current view was that galaxies formed via smaller galaxies clumping together. "But there seem to be other galaxies where that idea doesn't work. By being able to study some of the formation processes in more detail with Herschel, we might be able to unlock the secret as to whether there's a different process for galaxies to form or whether all our models are correct."

Galaxies and stars formed from lumps of cold gas collecting together and then igniting, Dr Fluke said. Infrared astronomy is the only way to observe this process. "We're looking at temperatures of minus 200 degrees, or even minus 250 degrees. They're very cold places in the universe and cold gas must somehow collect together to form stars, at which point the gas heats up and it becomes visible."

Dr Hopkins said the Anglo-Australian Telescope — which primarily uses the observatory at Siding Springs in northern NSW — would be collaborating with Herschel astronomers to study galaxy formation.

"We will be combining our measurements with theirs to identify the relationship between dust and star formation in galaxies and how these depend on the mass of a galaxy and the environment — clusters, groups or voids — in which a galaxy lives."

Dr Fluke said Herschel would also be looking very close to home, within our own solar system. "Some of the other things that it's good for is looking at the atmosphere of comets and planets in more detail.

"By looking at what's on comets, we have a clue what the early solar system was like and it gives us a better idea of how the Earth developed and got its atmosphere."

And, he said, there was the thrill of the unexpected.

"Although we have a vague idea about what we hope to find," Dr Fluke said, "I also expect there'll be other things that we never thought would be there — which is what happens when you have a new telescope."

Secrets of the cosmos: the answers to all the biggest questions in the universe

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At the Culham Science Centre in Oxfordshire they make stars every day – one every 15 minutes, when everything is going to plan. Star-makers on Earth generally use two heavy forms of hydrogen called deuterium and tritium. On Earth, they need hydrogen plasma. We are used to seeing, say, water as either a solid (ice), a liquid (water) or a gas (steam). But there is also a fourth state of matter – plasma. It forms under extreme conditions, such as those that occur inside a bolt of lightning, or inside stars. At millions of degrees, atoms are stripped of their electrons and separate into a sort of electrically charged cloud.

Magnets can be used to manipulate this electrically charged plasma. The Culham star-making machine squeezes it tightly into a sort of magnetic bottle. As the power is cranked up, and the plasma squeezed more tightly, it eventually does a remarkable thing: it ignites as a tiny star. The intense glow doesn't last long. Scientists film it in ultra-slow motion to see how it starts and, more importantly, why it breaks down after such a short time.

In the fiery furnace, hydrogen succumbs to the heat and pressure, and some of the hydrogen nuclei fuse to make a new element, helium. The energy that is released should, in theory, help to raise the temperature and keep the reaction going – something the Sun and the other stars manage to do for billions of years. At Culham, they are still working on it. But, with the turning of one element into another, the process that happens in stars has begun. In the lab, the nuclear fusion goes no further but, in stars, more and more fusion takes place, making heavier and heavier elements, all the way up to iron.

2) We're all being stretched, all the time

Although Isaac Newton's famous work told us what gravity does, he did not explain what it is. Particularly bothering was the implication that gravity acted instantly: if you could somehow conjure a second Sun in the sky, in Newton's world, the Earth would feel its pull immediately. But Albert Einstein didn't like the idea of something acting instantly at a distance, and instead thought of gravity as acting locally on space. He imagined massive objects making a "dent" in space into which others could fall. Although the "dent" would be deepest close to the object, it would reach across the universe so that Earth would be attracted even by distant stars. If a new large object were created, or an existing one moved, Einstein predicted, it would create ripples across the universe, travelling at the speed of light.

Unfortunately, he also predicted that, by the time they reached us, these ripples – called gravitational waves – would be far too faint to detect. Rather than a prediction of failure, some people have taken this as a challenge.

The site of the European Gravitational Observatory (EGO) near Pisa in Italy is a contrast to those selected for optical telescopes. It is on a flat plain, rather than a mountain; in a frequently cloudy area, and close to a town. The main requirement was to find a patch of flat ground measuring 1.8 miles square, because the Virgo detector is huge. The principle of detecting gravitational waves is very simple. As they pass through Earth, the waves slightly change the length of everything. Imagine a football pitch. As a gravitational wave goes through it is stretched first one way, so it gets shorter and fatter; then the other, so it gets longer and thinner, before returning to its original shape. So gravitational-wave detectors have two arms at right angles, with sensitive equipment measuring the length of the arms. If this sounds simple, it isn't. The expected change in length of each of the 1.8-mile arms will be the same as one-thousandth the diameter of a hydrogen atom's nucleus.

3) The zero-gravity lavatory

In the early days of space flight astronauts wore nappies ("intimate contact devices" in Nasa's euphemism), but these were not acceptable for flights of longer than a few hours. For Skylab there was a new system of waste management – the Waste Collection System (WCS) with a modesty curtain to shield the user from view. The WCS comprised a cylinder about 50in high and 12in across, like an old-fashioned spin dryer. From the front came a flexible plastic hose, as from a vacuum cleaner. This urine collector was intended for both men and women, and was fitted with a triangular rubber nozzle on the end. Unfortunately the sexes have different peeing systems, and as a result the nozzle never fitted anyone very well. What's more, the vacuum was never much good, so the nozzle was always a bit wet from the last user.

The alternative involved taking your trousers down and sitting on top of the cylinder, with your feet in stirrups, and then pulling a pair of spring-loaded restraints over your thighs. Remember, you were weightless, and you would not want to float off in the middle of the operation. Then you opened the sliding lid and...

Next problem: zero gravity. The seat was fitted with 11 channels to blow air upwards from all around so as to cause faeces to fall. Unfortunately, the air was icy cold. Once inside the cylinder, the matter was spun to the outside and freeze-dried to keep it out of the way.

At least one astronaut ate nothing at all for an entire mission in order to avoid having to use the WCS. But, sadly, this stratagem does not work. The body produces solid waste even when it receives no food.

4) Gravitational wobble

When a massive planet, such as Jupiter, orbits the Sun it exerts a gravitational pull on the Sun, which by Newton's third law (action and reaction are equal and opposite) must be the same as the pull needed to keep Jupiter in orbit. This means that Jupiter does not revolve around a stationary Sun; rather the pair of them actually revolve around a common centre of gravity. Because the Sun is a thousand times more massive than Jupiter, this centre of gravity is below the surface of the Sun, but it is still well away from the Sun's core, and as Jupiter swings round to the "east" the Sun will be swinging "west" to balance the pair.

5) Did life come from outer space?

The idea that life might have started all over the universe by seeding from space is called panspermia. In 1996 a meteorite from Mars was found to contain what appeared to be fossilised bacteria. According to the idea of panspermia, biological seeding from space not only kick-started life on Earth, but continues, and may be responsible for some of our diseases and infections.

We now know that, even in the emptiness of space, there are many kinds of molecules floating about, and some of them are complex organic compounds. Organic compounds have also been found inside meteorites – chunks of metal and rock that fall to Earth.

Where did those organic compounds come from? One wild theory is they were left behind, either by mistake or on purpose, by alien creatures touring through the galaxy. Another possibility is that they were formed naturally from simple molecules under the influence of ultraviolet light from the Sun – and, presumably, from other stars, too.

If organic compounds are drifting about in "empty" space, then they might have floated down through our atmosphere – or fallen inside a meteorite – and started reacting in ponds and shallow seas when conditions were favourable. Alternatively, they could have been part of the original cloud of dust that was pulled together to create Earth 4,500 million years ago. In that case they must have survived millions of years of Earth's turbulent early history before the climate settled down into a favourable state.

Various fragments of evidence support the idea that living things could migrate through space: high-altitude balloons have detected bacteria 20-25 miles above Earth's surface, in concentrations apparently increasing with altitude, suggesting that the bacteria either came from space or that bacteria from Earth could drift into space. Also, sudden showers of red rain in the Indian state of Kerala in late summer 2001 contained red material that was originally thought to be dust, but appeared under electron microscopes to be living cells. Some scientists thought these were simple algal spores, but others claimed they contained no DNA, and must therefore be some form of extraterrestrial life.

The idea that bacteria could survive the vacuum of space may seem absurd, but in 1967 the unmanned American probe Surveyor 3 landed a television camera on the Moon; it was retrieved in 1969 by Apollo 12, and when examined was found to contain a little colony of a bacterium called Streptococcus mitis. These had survived on the Moon, in a vacuum and with extreme monthly temperature changes, for 31 months. So perhaps bacterial life could indeed have come from outer space.

6) Stars can create their own telescopes

In his famous paper on general relativity, Albert Einstein said that gravity does not really make two masses attract one another; instead it distorts space in such a way that the two are pulled together. One consequence of this is that a massive star distorts the space around it.

So the space around the star acts as a lens, attracting light rays towards its centre, and thus magnifying the image of a distant object on the far side. This happens when, by chance, a star passes in front of a distant planet, which then flashes bright for between a few minutes and an hour or so.

Using this method, a planet called OGLE-2005-BLG-390Lb was found on 25 January 2005; it orbits a red dwarf 21,500 light years away. It seems to have a mass only 5.5 times that of Earth, and is nearly three times as far from its own star as we are from the Sun.

The Cosmos: A Beginners Guide by Adam Hart-Davis, is published by BBC Books, an Ebury Publishing imprint. © Adam Hart-Davis and Paul Bader. To buy a copy at the special price of £13.50, including P&P, call Independent Books Direct on 08700 798897 or go to www.independentbooksdirect.co.uk

Biggest black holes may grow inside 'quasistars'

The biggest black holes in the universe might have grown within the bellies of giant stars, a new study suggests. If these hole-bearing "quasistars" exist, then they might be bright enough to see from across the universe.

Quasistars are one attempt to explain the existence of supermassive black holes, which astronomers have detected at the hearts of most large galaxies, and whose origin is still unknown.

Smaller black holes are easier to account for - a massive star's core can sometimes collapse into a black hole with around 10 times the mass of the Sun. But their big brothers can be a billion times as massive.

It is possible that the smaller siblings can grow that big by eating stars and gas or by colliding with each other and merging. But they would have to grow up very quickly in cosmic terms, because some supermassive black holes were already around just a few hundred million years after the big bang.

Mitchell Begelman and colleagues at the University of Colorado in Boulder, US, have worked out how the big holes might have gotten a head start in life.

Large clouds of hydrogen and helium were common in the early universe. Begelman says that if such a cloud collapsed into a massive star, a dense knot of the gas could pile up so rapidly in its core that it would collapse into a small black hole.

When that happens in stars just a few times as massive as the Sun, the enormous energy released is enough to blast away the surrounding layers of gas, revealing a brilliant supernova explosion.

Great bulk

But as long as a quasistar is at least 1000 times the mass of the Sun, its great bulk could have absorbed all that energy, containing the supernova with no more than a shudder, becoming a black-hole sun.

The black hole embryo could then grow fast, nourished by the dense body of the quasistar. Gas falling onto the hole would heat up and release an immense amount of light, so much that its pressure would hold up the layers of the star above it.

That could lead to a potentially unstable situation, with dense gas sitting on a lighter layer. Begelman suspects that the pressure would be released as some of the light would escape in "photon bubbles", large blobs of radiation that would burst from the surface of the star. "My guess is it would have to be bubbly," Begelman told New Scientist.

Gestation would last about a million years, at which point the hole could reach at least 10,000 solar masses - not yet an adult supermassive black hole, but a pretty big baby. With such a head start, it would be relatively easy to reach a billion solar masses on a diet of stars and other black holes.

Bright beacons

Astronomers may be able to test the idea by searching for the objects. A quasistar would be a little cooler than our Sun, Begelman calculates, but at more than 10 billion kilometres across, it would produce about as much light as a small galaxy.

Detecting them will be difficult, however. They are most likely to have existed in the early universe, when stars are thought to have been much more massive than today. The expansion of space since then would have stretched their light into a band of the infrared spectrum that is absorbed by Earth's atmosphere.

The James Webb Space Telescope, due for launch in 2013, will be sensitive to infrared light and might be able to spot quasistars, although even then they would appear dim.

Biggest black holes may grow inside 'quasistars'

The biggest black holes in the universe might have grown within the bellies of giant stars, a new study suggests. If these hole-bearing "quasistars" exist, then they might be bright enough to see from across the universe.

Quasistars are one attempt to explain the existence of supermassive black holes, which astronomers have detected at the hearts of most large galaxies, and whose origin is still unknown.

Smaller black holes are easier to account for - a massive star's core can sometimes collapse into a black hole with around 10 times the mass of the Sun. But their big brothers can be a billion times as massive.

It is possible that the smaller siblings can grow that big by eating stars and gas or by colliding with each other and merging. But they would have to grow up very quickly in cosmic terms, because some supermassive black holes were already around just a few hundred million years after the big bang.

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Mitchell Begelman and colleagues at the University of Colorado in Boulder, US, have worked out how the big holes might have gotten a head start in life.

Large clouds of hydrogen and helium were common in the early universe. Begelman says that if such a cloud collapsed into a massive star, a dense knot of the gas could pile up so rapidly in its core that it would collapse into a small black hole.

When that happens in stars just a few times as massive as the Sun, the enormous energy released is enough to blast away the surrounding layers of gas, revealing a brilliant supernova explosion.

Great bulk
But as long as a quasistar is at least 1000 times the mass of the Sun, its great bulk could have absorbed all that energy, containing the supernova with no more than a shudder, becoming a black-hole sun.

The black hole embryo could then grow fast, nourished by the dense body of the quasistar. Gas falling onto the hole would heat up and release an immense amount of light, so much that its pressure would hold up the layers of the star above it.

That could lead to a potentially unstable situation, with dense gas sitting on a lighter layer. Begelman suspects that the pressure would be released as some of the light would escape in "photon bubbles", large blobs of radiation that would burst from the surface of the star. "My guess is it would have to be bubbly," Begelman told New Scientist.

Gestation would last about a million years, at which point the hole could reach at least 10,000 solar masses - not yet an adult supermassive black hole, but a pretty big baby. With such a head start, it would be relatively easy to reach a billion solar masses on a diet of stars and other black holes.

Danger ahead as the Sun goes quiet

THE sun's ability to shield the solar system from harmful cosmic rays could falter in the early 2020s, just in time to threaten the health of NASA astronauts as they return to the moon.

As well as the 11-year cycle of sunspots and solar flares, the sun's activity experiences longer-term shifts lasting several decades. The sun is currently in a long-term high, having been relatively active for nearly a century, but it is not known when this will end.

To find out, a team led by Jose Abreu of the Swiss Federal Institute of Aquatic Science and Technology in Duebendorf analysed 66 long-term highs from the past 10,000 years, as recorded in fluctuating levels of rare isotopes such as beryllium-10 in ice cores from Greenland. These are produced when cosmic rays break down the nuclei of oxygen and nitrogen atoms in the Earth's atmosphere. Production of these isotopes peaks when ...

how big can a black hole grow?

Two astronomers reckon they have worked out the answer: colossal black holes with a mass of up to 50 billion suns could be lurking out there - but that's the limit.

Giant black holes sit at the cores of virtually all galaxies, and are thought to have grown from smaller seed black holes that swallowed lots of matter. The biggest well-measured one resides in the galaxy Messier 87 and has the mass of 3 billion suns, a measurement based on the speed of the gas swirling around it.

Even bigger black holes are waiting to be found, say Priya Natarajan of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and Ezequiel Treister of the European Southern Observatory in Santiago, Chile.

In a study to appear in Monthly Notices of the Royal Astronomical Society, the pair examined the "feeding habits" and growth of black holes. They used data from surveys carried out by other teams that observed the X-rays and visible light emitted by matter as it is devoured by black holes. The properties of this radiation can be used to estimate a black hole's mass and how quickly it is gobbling up its surroundings.

The team analysed how many galactic black holes of various masses were present at each stage in the universe's history. The distribution of masses they found today and in the past can only be explained if there is a limit on how fast black holes can grow, the researchers say.

Ultramassive black hole

Previous studies have also suggested this, and it may be due to the way radiation from infalling matter blasts the black hole's neighbourhood free of additional sustenance. "They self-regulate," says Natarajan. "They never grow beyond a certain mass in any epoch."

Knowing this growth rate allowed them to work out the modern-day size of the biggest known black holes that existed in the early universe. Back then, they are estimated to have had the mass of about a billion suns. According to Natarajan and Treister, a few black holes of this size may have bloated to "ultramassive" size by now, with between 5 and 50 billion times the sun's mass, at the most. Even a black hole at the lower end of this range would be gargantuan - more than 3 times as wide as our solar system.

One ultramassive black hole may already have been spotted 3.5 billion light years away in the galaxy OJ 287, which is thought to harbour a pair of giant black holes circling each other at its centre. The larger of the two has been estimated to be 18 billion solar masses, based on the properties of radiation outbursts from the system, but astronomers disagree on how accurate this is.

Scott Tremaine at the Institute for Advanced Study in Princeton, New Jersey, says that examining the growth history of black holes is important because it appears to be closely tied to the growth of galaxies, including our own.

But he cautions that estimating black hole masses from the amount of radiation they give off - as Natarajan and Treister have done - is fraught with uncertainty because a black hole's brightness can vary depending on how much material it eats.

The Worst Kept Secret In The Universe

Israel's nuclear weapon arsenal is arguably the worst kept secret in the world. There seems little logical point to continue to pretend you don't have them after forty years. The Israeli Lobby is screaming bloody murder anyway, because the Obama administration wants Israel to admit is has nukes and wants it to sign the Nuclear Non-Proliferation Treaty.

President Obama's efforts to curb the spread of nuclear weapons threaten to expose and derail a 40-year-old secret U.S. agreement to shield Israel's nuclear weapons from international scrutiny, former and current U.S. and Israeli officials and nuclear specialists say.

The issue will likely come to a head when Israeli Prime Minister Benjamin Netanyahu meets with Mr. Obama on May 18 in Washington. Mr. Netanyahu is expected to seek assurances from Mr. Obama that he will uphold the U.S. commitment and will not trade Israeli nuclear concessions for Iranian ones.

Assistant Secretary of State Rose Gottemoeller, speaking Tuesday at a U.N. meeting on the nuclear Non-Proliferation Treaty (NPT), said Israel should join the treaty, which would require Israel to declare and relinquish its nuclear arsenal.

"Universal adherence to the NPT itself, including by India, Israel, Pakistan and North Korea, ... remains a fundamental objective of the United States," Ms. Gottemoeller told the meeting, according to Reuters.

Which makes sense to me. However, Israel and its supporters see this as akin to the most foul betrayal imaginable by Obama, and are readily making it known that this will never, never happen.

Mr. Netanyahu, whose meeting with Mr. Obama on May 18 will be the first since both took office, raised the issue of the nuclear understanding during a previous tenure as prime minister.

Israeli journalists and officials said Mr. Netanyahu asked for a reaffirmation and clarification of the Nixon-Meir understanding in 1998 at Wye River, where the U.S. mediated an agreement between Israel and the Palestinians. Mr. Netanyahu wanted a personal commitment from President Clinton because of concerns about a treaty that Mr. Clinton supported to bar production of fissile materials that can be used to make weapons. Israel was worried that the treaty would apply to de facto nuclear states, including Israel, and might oblige it to allow inspections of Dimona.

In 2000, Israeli journalist Aluf Benn disclosed that Mr. Clinton at Wye River promised Mr. Netanyahu that "Israels nuclear capability will be preserved." Mr. Benn described as testy an exchange of letters between the two leaders over the Fissile Material Cut-Off Treaty. He said Mr. Netanyahu wrote Mr. Clinton: "We will never sign the treaty, and do not delude yourselves - no pressure will help. We will not sign the treaty because we will not commit suicide."

The Bush administration largely dropped the treaty in its first term and reopened negotiations in its second term with a proposal that did not include verification.

It will be interesting nonetheless. But at every turn Israel has won every concession it has demanded from the US, despite strong language from the Obama White House. Israel certainly has every right to exist as a sovereign country and to defend itself. But let's be honest...the country has nukes and refuses to admit them, just as it accuses Iran of doing.

Does the Universe have a secret? If you say 'no', then you must already know everything. This is the true story of how I stumbled on the long sought after 'unification theory' or 'theory of everything' or 'quantum gravity,'... completely by accident. I wasn't even looking for the answer to the mysteries of 'dark matter' or 'dark energy.' I just tripped over them by mistake.

The New History of Black Holes: 'Co-evolution' Dramatically Alters Dark Reputation

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.
Black Holes & Co-evolution: A Primer
A merger may have triggered the output of energy in this galaxy, Centaurus A.
The puzzleVery compact but bright objects called quasars, which can outshine a thousand normal galaxies, were abundant when the universe was less than 10 percent of its present age. Quasars are powered by black holes weighing more than a billion suns. How did they get so big so fast?
The front-running theoryCo-evolution holds that galaxies and supermassive black holes evolve together, each counting on the other for its ultimate heft. If true, and once fully understood, the new theory should help solve the growth puzzle.
The evidence
Early quasars appear to be surrounded by large galaxies loaded with tons of gas, which fuels star formation and feeds the black holes, a report last week suggested.
Black hole mass increases with galactic bulge mass.Near the quasars in time are other, normal galaxies that have likely just passed through a quasar phase, as seen in images released earlier this month.
Central bulges of stars in many galaxies, such as our Milky Way, are directly related to the masses of the black holes buried inside, as detailed in June of 2000. A galaxy's dimensions seem tied to its black hole's dietary habits.
Most black hole mass seems to come from direct consumption (called accretion) of gas, indicating that a black hole needs a surrounding galaxy to grow.
Dark matter is studied in part by examining hot gas clouds like this one.
The dark horseA halo of mysterious dark matter is thought to infuse the space surrounding each of the bulge-packing galaxies. The invisible gravity generator would play a crucial role in galaxy and black hole construction.
The also-ransIf co-evolution reigns, as most researchers believe, then two older (but not-dead-yet) theories are wrong: that a galaxy forms first and directs the development of a black hole; or that a black hole is generated first, providing the seed around which a galaxy can coalesce. It is also possible that different types of galaxies form by different means, and that co-evolution will only be found to describe one path to galactic adulthood.
-- Robert Roy Britt
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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.

Black Holes and Galaxy Formation

Carnegie Mellon physics professor Tiziana Di Matteo is finding the answers to long-standing questions about black holes and how they help shape the galaxies.
For years, scientists have observed that the total mass of stars in today's galaxies corresponds directly to the size of a galaxy's black hole. But until now, no one could account for this observation. By incorporating Di Matteo's calculations for black hole dynamics into a computational model of galaxy formation, researchers have been able to piece together the evolution of galaxies more accurately.
"With these computations, we now see that black holes must have an enormous impact on the way galaxies form and evolve," said Di Matteo.
Her work was recently featured in Monster of the Milky Way, a NOVA documentary about black holes. Viewers were treated to stunning computer imagery as researchers revealed new insights into one of the most destructive objects of the universe.
Super-massive black holes, whose activities Di Matteo simulates as part of her research, lie at the heart of most, if not all, large galaxies. They are formed through the collision of galaxies drawn together by the pull of gravity, and once formed, these powerful giants consume all of the cosmic matter that surrounds them.
Could the black hole believed to lie at the center of our galaxy flare up and consume our entire galactic neighborhood?
"When our galaxy collides with the Andromeda galaxy, which has a black hole almost 10 times larger than our Milky Way's, their black holes will merge and all the gas and stars will be rearranged to form a giant new galaxy," explained Di Matteo.While Di Matteo acknowledged a chance that our solar system might end up close enough to a new black hole to be swallowed up, she added, "we should only worry about this if we are planning to be around in 2 billion years' time