THE FINAL THEORY: Rethinking Our Scientific Legacy

          
DARK ENERGY ARTICLE EXCERPTS

"Dark Energy Fills The Cosmos"

"The universe is made mostly of dark matter and dark energy," says Saul Perlmutter, leader of the Supernova Cosmology Project headquartered at Berkeley Lab, "and we don't know what either of them is."

"Astrophysics Challenged By Dark Energy Finding"

"This starts to look incredibly ugly and complicated," says Mario Livio of the Space Telescope Science Institute. "I even wonder if we are we asking right questions." "Dark energy is something we have no clue as to what is causing it, and it doesn't fit into current physics theories, and they have to develop new approaches to explain it," said Perlmutter, an astrophysicist at the Lawrence Berkeley National Laboratory. "One of our goals is to test for dark energy and see if this is preposterous because we are just dead wrong, or find out that we really do live in a preposterous universe," says astrophysicist Michael Turner of the University of Chicago.

"New South Pole Telescope to Study Mysterious Dark Energy"

According to one idea, dark energy is Albert Einstein's cosmological constant: a steady force of nature operating at all times and in all places. Einstein introduced the cosmological constant into his theory of general relativity to accommodate a stationary universe, the dominant idea of the day. Another version of the dark energy theory, called quintessence, suggests a force that varies in time and space. Some scientists even suggest there is no dark energy at all, and that gravity merely breaks down on vast intergalactic scales.

"More evidence for the accelerating universe"

The energy density of the universe is composed of matter and the energy density of the vacuum. The size of the latter, which is sometimes called quintessence or "dark energy", defines the cosmological constant. This constant was first introduced by Einstein to explain why the universe did not appear to be expanding. Hubble later showed that the universe was expanding, causing Einstein to call it his "biggest blunder". Although some astronomers still have doubts about the accelerating universe, evidence in its favour continues to grow. All of which means that the accelerating universe still presents lots of challenges to astronomers.

"Dark Energy: Astronomers Hot on Trail of Mysterious Force"

At first there was disbelief. Then widespread befuddlement. Then a period of quantification. Now, five years after discovering that the universe is expanding at an ever-faster pace, scientists know exactly how much mysterious "dark energy" is behind the acceleration and have turned to figuring out what it is. The task may eat up a lifetime, researchers admit. Or perhaps some new Einstein will figure it out next year in a light-bulb moment. Scientists admit they've made almost zero progress in understanding dark energy. They have no idea what it is or how it works. Various researchers describe the phenomenon as a repulsive force, as vacuum energy, as anti-gravity, and as possibly no more than a different manifestation of gravity over large distances. Some say the repulsion could be a response to dark matter, unseen stuff that is known to make up nearly a quarter of the universe, but such a link has never been established. Michael Turner, one of the world's foremost cosmologists from the University of Chicago, said solving the dark energy problem "is going to require a crazy idea."

"Dark Energy: Astronomers Still 'Clueless' About Mystery Force Pushing Galaxies Apart"

It sounds like something out of a Star Trek episode: Dark energy, a mysterious force that no one understands, is causing the universe to fly apart faster and faster. Only a few years ago, if you'd suggested something like that to astronomers, they would have told you to spend less time in front of the TV and more time in the "real" world. But dark energy is real or at least, a growing number of astronomers think it is. These researchers found that the supernovas were dimmer than they should have been, and that meant they were farther away than they should have been. The only way for that to happen, the astronomers realized, was if the expansion of the universe had sped up at some time in the past. Other researchers questioned the result; perhaps the supernovas were dimmer because their light was being blocked by clouds of interstellar dust. Or maybe the supernovas themselves were intrinsically dimmer than scientists thought. But with careful checking, and more data, those explanations have largely been put aside, and the dark energy hypothesis has held up. No one, however, can truly explain it. "Frankly, we just dont understand it," says Craig Hogan, an astronomer at the University of Washington at Seattle. "We know what its effects are," Hogan says, but as to the details of dark energy, "Were completely clueless about that. And everybodys clueless about it." In one sense, the idea is not completely new. Einstein had included such an "anti-gravity" effect in his theory of general relativity, in his so-called cosmological constant. But Einstein himself, and later many other astronomers, came to regard this as a kind of mathematical contrivance that had little relationship to the real universe. Still, anti-gravity isnt the right way to describe dark energy, says Virginia Trimble of the University of Southern California at Irvine. "It doesnt act opposite to gravity," Trimble says. "It does exactly what general relativity says it should do, if it has negative pressure." Dark energy is causing quite a bit of upset for astronomers who have to adjust to an unexpected and outlandish new view of the universe. Already, they have had to accept the notion of dark matter, which is now thought to far outnumber ordinary matter in the universe, but which has never been detected in any laboratory. Now, the arrival of an unknown force that rules cosmic expansion has added insult to injury. "When you teach undergraduates, and they say, 'Well, what is dark matter?' Well, nobody's really sure. 'What is dark energy?' We're even less sure. So you have to explain to a student, that 90 percent of the universe, 95 percent, is in two ingredients that nobody really understands," says Ellis. "This isn't really progress." "It took two generations for people to be comfortable with quantum mechanics," she says. "The fact that you do not have good intuition about [dark energy] is true for quantum mechanics, general relativity, and lots of other things, because we cant easily mock them up in the laboratory." "If the supernova results were not to hold up … because supernova were found to be different at early times than today -- perhaps they're dimmer for some reason we don't understand -- then the universe wouldn't be accelerating," Ellis says. "I think it's unlikely, but I think it's so important that we have to check. It's such a big claim, and it's so counter-intuitive that the universe would be accelerating, in my opinion, that no stone should be left unturned. We should verify this as best as we possibly can."

"What Is the Universe Made Of?"

In the past few decades, cosmologists have discovered that the ordinary matter that makes up stars and galaxies and people is less than 5% of everything there is. Grappling with this new understanding of the cosmos, scientists face one overriding question: What is the universe made of? Even multiplying all the visible "ordinary" matter by 10 doesn't come close to accounting for how the universe is structured, and there isn't enough visible matter to keep galaxies spinning at the right speed. Cosmologists now conclude that the gravitational forces exerted by another form of dark matter, made of an as-yet-undiscovered type of particle, must be sculpting these vast cosmic structures. They estimate that this exotic dark matter makes up about 25% of the stuff in the universe--five times as much as ordinary matter. But even this mysterious entity pales by comparison to another mystery: dark energy. In the late 1990s, scientists examining distant supernovae discovered that the universe is expanding faster and faster, instead of slowing down as the laws of physics would imply. Is there some sort of antigravity force blowing the universe up? Ordinary matter and exotic, unknown particles together make up only about 30% of the stuff in the universe; the rest is this mysterious anti-gravity force known as dark energy. What is exotic dark matter? And finally, what is dark energy? This question, which wouldn't even have been asked a decade ago, seems to transcend known physics more than any other phenomenon yet observed. At the moment, the nature of dark energy is arguably the murkiest question in physics.

"Dark Energy and Dark Matter – The Results of Flawed Physics?"

There are few scientific concepts as intriguing and mysterious as dark energy and dark matter, said to make up as much as 95 percent of all the energy and matter in the universe. And even though scientists don't know what either is and have little evidence to prove they exist, dark energy and dark matter are two of the biggest research problems in physics. But what if they were conceived in error? This is what three Italian physicists have recently asked. In a paper in the August 3 online edition of the Institute of Physics' peer-reviewed Journal of Cosmology and Astroparticle Physics, they put forth the idea that scientists were forced to propose the existence of dark energy and dark matter because they were, and still are, working with incorrect gravitational theory. "Our proposal implies that the 'correct' theory of gravity may be one based solely on directly observed astronomical data," said lead author Salvatore Capozziello, a theoretical physicist at the University of Naples. Dark energy and dark matter were originally conceived to explain, respectively, the accelerating expansion of the universe (despite the tendency of gravity to push matter together) and the discrepancy between the amount of matter scientists expect to observe in the universe but have not yet found. Astronomers suggested the existence of dark matter when they noticed something odd about spiral galaxies: Stars at the middle and edge of a spiral galaxy rotate just as fast as stars near the very center. But according to Newtonian mechanics, stars further away from the galactic center should rotate more slowly. Scientists thus assumed that some sort of "dark" matter, not observable by emitted light, must be boosting the total gravity of the galaxy, giving the stars extra rotational speed. "We can show that no 'exotic' ingredients have to be added to fill the gap between theory and observations," said Capozziello. Despite this, the notion that dark matter and dark energy are "wrong" is potentially very unpopular.

            
          
BIG BANG ARTICLE EXCERPTS

"Welcome to the new age of enlightenment"

"Often in error but never in doubt." This accusation has sometimes been levelled against cosmologists - and justifiably so. They have frequently embraced poorly grounded speculations with irrational fervour, and been led by wishful thinking to read too much into vague and tentative evidence.

"Universe in crisis as experts question Big Bang model"

The widely accepted idea that the universe began with a Big Bang could be wrong, according to astrophysicists who took part in a "Crisis in cosmology" meeting in Portugal and reported in this month's Physics World magazine. Eric Lerner of Lawrenceville Plasma Physics, who organized the Portuguese meeting, says that certain properties of the cosmic microwave background - the so-called "echo of the Big Bang" - do not match predictions from the theory. Others are unhappy that cosmologists have had to introduce weird concepts like dark matter and dark energy to explain the universe. Mainstream scientists, however, have hit back, saying that we just need to tweak the Big Bang model and tie up "loose ends".

" 'Brane-Storm' Challenges Part of Big Bang Theory"

A movement has taken hold that would blow one of the basic tenets of the Big Bang to smithereens. "It's almost crazy enough to be correct," says Michael Turner, a longtime University of Chicago cosmologist. Turner said astronomers have reacted with great excitement to the new theory, in part because the idea of alternate dimensions is largely new to most of them. Cosmologists tend to welcome the idea as a healthy potential alternative to certain aspects of the Big Bang. In textbooks a century from now, Turner believes there will be one of the following two paragraphs: "A hundred years ago, people were so desperate to try to understand how to put it all together, they invented additional spatial dimensions. What were they smoking?" Or: "A hundred years ago, people were so provincial that in spite of much evidence that there should be extra dimensions they refused to accept it."

"Big bang pushed back two billion years"

The new observation implies that the value used for the constant is off by 15%, says Przybilla. That suggests the universe is 15% larger, and 15% older than previously thought. Recent estimates have put the age of the universe at 13.7 billion years, and the new research suggests it may actually be 15.8 billion years old. "Our result hints that there may be something interesting happening with the Hubble constant," says Norbert Przybilla at the University of Erlangen-Nuremberg, Germany.

"New String-Theory Notion Redefines the Big Bang"

The problem with the Big Crunch/Big Bang model is that the mathematical laws of classical general relativity do not work at a singularity. And if scientists cannot mathematically understand the singularity, they cannot, in theory, fully understand the geometry of spacetime, either before the Big Crunch or after the Big Bang.

"New Look At Microwave Background May Cast Doubts On Big Bang Theory"

A new analysis of 'cool' spots in the cosmic microwave background may cast new doubts on a key piece of evidence supporting the big bang theory of how the universe was formed. Proving Einstein right might become a problem for the standard cosmological model of how the universe was formed because Einstein's theory also predicts that the cosmic microwave background shouldn't look the way it does, according to Dr. Richard Lieu, a physics professor at The University of Alabama in Huntsville. "There appear to be no lensing effects whatsoever. This lack of variation is a serious problem." Lieu says cosmologists are left with several alternative explanations. The first is that the cosmological parameters used to predict the original, pre-lensed sizes of the cool and hot spots in the microwave background might be wrong, but this still result in an overhaul of the standard model. The most contentious possibility is that the background radiation itself isn't a remnant of the big bang but was created by a different process, a "local" process so close to Earth that the radiation wouldn't go near any gravitational lenses before reaching our telescopes. Although widely accepted by astrophysicists and cosmologists as the best theory for the creation of the universe, the big bang model has come under increasingly vocal criticism from scientists concerned about inconsistencies between the theory and astronomical observations, or by concepts that have been used to "fix" the theory so it agrees with those observations. These fixes include theories which say the nascent universe expanded at speeds faster than the speed of light for an unknown period of time after the big bang; dark matter; and dark energy, an unseen, unmeasured and unexplained force that is apparently causing the universe not only to expand, but to accelerate as it goes. Recent observations by NASA's new Spitzer space telescope found "old" stars and galaxies so far away that the light we are seeing now left those stars when (according to big bang theory) the universe was much too young to have galaxies with red giant stars that have burned off all of their hydrogen. Other observations found clusters and super clusters of galaxies at those great distances, when the universe was supposed to have been so young that there had not been enough time for those monstrous intergalactic structures to form.

"No Big Bang? Endless Universe Made Possible by New Model"

A new cosmological model demonstrates the universe can endlessly expand and contract, providing a rival to Big Bang theories and solving a thorny modern physics problem, according to University of North Carolina at Chapel Hill physicists.

"New data clouds cosmic distance measurements"

A new measurement of the distance to the Pleiades star cluster is casting doubt on the reliability of one of astronomy's most widely used databases, reigniting a seven-year controversy over how cosmic distances are determined.

"Hubble tackles paradox of Universe's age"

One troubling implication was that the oldest stars in our galaxy appeared to have formed before the Universe began expanding. Astronomers had previously put the Universe's age at nine billion years, based on the current rate of expansion. But Freeman says that including the effects of dark energy raise the age to 13 to 14 billion years.

"Surprising telescope observations shake up galactic formation theories"

A heavy form of hydrogen created just moments after the Big Bang has been found to exist in larger quantities than expected in the Milky Way, a finding that could radically alter theories about star and galaxy formation, says a new international study led by the University of Colorado at Boulder.

"NASA Researcher Finds Evidence That The Universe May Be Younger Than Previously Thought"

Dr. Eyal Maoz of NASA Ames Research Center, Moffett Field, CA, and astrophysicists from a variety of U.S. and Canadian institutions have found evidence suggesting that the universe may be younger than scientists had previously thought, and that it is expanding faster than expected. This implied relatively low age of the universe revives an old paradox in the field of astrophysics that the universe seems to be younger than some of the stars in it. The finding suggests that a revision of the cosmological model may be required.

"Study Questions Big Bang (Scientists Question the Study)"

A study of nearby galaxy clusters has failed to detect distortions in the ancient microwave radiation many scientists have linked to the creation of our universe. The finding could cast doubt on the entire Big Bang theory, but other experts have serious misgivings about the results. They say the space probe used in the study is not the ideal instrument for detecting the distortions and that the discrepancy is less a reflection of problems with the Big Bang theory than of how little scientists really know about galaxy clusters.

"Are galaxy clusters corrupting Big Bang echoes?"

In recent years, astronomers have obtained detailed measurements of the cosmic microwave background radiation - the 'echo' from the birth of the Universe during the Big Bang. These results appear to indicate with remarkable precision that our Universe is dominated by mysterious 'cold dark matter' and 'dark energy'. But now a group of UK astronomers has found evidence that the primordial microwave echoes may have been modified or 'corrupted' on their 13 billion year journey to the Earth. The consequences for cosmology could be highly significant. The signature for dark energy and dark matter lies in the detailed structure of the ripples detected in the microwave background. If this primordial pattern has been corrupted by processes taking place in the recent past, then it will, at best, complicate the interpretation of the microwave echo and, at worst, begin to undermine the previous evidence for both dark energy and cold dark matter. Both the WMAP and Durham results suggest that the microwave echo of the Big Bang may have had to come through many more obstacles on its journey to the Earth than had previously been thought, with consequent possible distortion of the primordial signal. "Our results may ultimately undermine the belief that the Universe is dominated by an elusive cold dark matter particle and the even more enigmatic dark energy," said Professor Shanks. The standard model does contain very uncomfortable aspects. These arise first because it is based on two pieces of "undiscovered physics" - cold dark matter and dark energy - neither of which has been detected in the laboratory. Indeed, the introduction of these two new components greatly increases the complication of the standard Big Bang inflationary model. The problems of dark energy run particularly deep: for example, its observed density is so small that it may be quantum mechanically unstable. It also creates problems for the theories of quantum gravity, which suggest that we may live in a Universe with 10 or 11 dimensions, all of them shrunk, with the exceptions of three in space and one in time. Many theorists would therefore like an escape route from today's standard model of cosmology and it remains to be seen how far these observations discussed by the Durham group will go in this direction. But if correct, they suggest that the rumours that we are living in a "New Era of Precision Cosmology" may prove to be premature!

"Did the big bang really happen?"

What if the big bang never happened? Ask cosmologists this and they'll usually tell you it is a stupid question. But a small band of researchers is starting to ask the question no one is supposed to ask. Last week the dissidents met to review the evidence at the first ever Crisis in Cosmology conference in Monção, Portugal. There they argued that cosmologists' most cherished theory of the universe fails to explain certain crucial observations. "Look at the facts," says Riccardo Scarpa of the European Southern Observatory in Santiago, Chile. "The basic big bang model fails to predict what we observe in the universe in three major ways." The temperature of today's universe, the expansion of the cosmos, and even the presence of galaxies, have all had cosmologists scrambling for fixes. "Every time the basic big bang model has failed to predict what we see, the solution has been to bolt on something new - inflation, dark matter and dark energy," Scarpa says. For Scarpa and his fellow dissidents, the tinkering has reached an unacceptable level. All for the sake of saving the notion that the universe flickered into being as a hot, dense state. "This isn't science," says Eric Lerner who is president of Lawrenceville Plasma Physics in West Orange, New Jersey, and one of the conference organisers. "Big bang predictions are consistently wrong and are being fixed after the event." So much so, that today's "standard model" of cosmology has become an ugly mishmash comprising the basic big bang theory, inflation and a generous helping of dark matter and dark energy. The trouble, says Lerner, who headed the list of more than 30 signatories, is that cosmology is bankrolled by just a few sources, and the committees that control those purse strings are dominated by supporters of the big bang. According to the accepted view, when we observe ultra-distant galaxies we should see them in their youth. But there is a problem. "We don't see young galaxies," says Lerner. "We see old ones. They have pretty much the same range of stars as present-day galaxies." And that is bad news for the big bang. So if there was no big bang, where did the cosmic microwave background come from? Rather than coming from the big bang, Lerner believes that the cosmic background radiation is really starlight that has been absorbed and re-radiated. It is an old idea that was widely promoted by the late cosmologist and well-known big bang sceptic Fred Hoyle. Lerner's idea is similar, though he thinks that threads of electrically charged gas called plasma are responsible. "All astronomers know that 99.99 per cent of matter in the universe is in the form of plasma, which is controlled by electromagnetic forces," he says. "Yet all astronomers insist on believing that gravity is the only important force in the universe. It is like oceanographers ignoring hydrodynamics." In Scarpa's case, the mysterious dark matter is at fault. Dark matter has become an essential ingredient in cosmology's standard model. That's because the big bang on its own fails to describe how galaxies could have congealed from the matter forged shortly after the birth of the universe. Cosmologists fix this problem by adding to their brew a vast amount of invisible dark matter which provides the extra tug needed to speed up galaxy formation. Scarpa's team believes the answer might be a breakdown of Newton's law of gravity, which says an object's gravitational tug is inversely proportional to the square of your distance from it. He insists that cosmologists are interpreting astronomical observations using the wrong framework. For now, his plea seems to be falling mostly on deaf ears. Yet there is more evidence that there could be something wrong with the standard model of cosmology. And it is evidence that many cosmologists are finding harder to dismiss because it comes from the jewel in the crown of cosmology instruments, the Wilkinson Microwave Anisotropy Probe (WMAP). "It could be telling us something fundamental about our universe, maybe even that the simplest big bang model is wrong," says João Magueijo of Imperial College London. The probe measures the way the temperature of the cosmic microwave background varies across the sky. Cosmologists believe that the tiny variations from one place to another are an imprint of the state of the universe about 300,000 years after the big bang. Rather than being spattered randomly across the sky, the spots in each pattern seemed to line up along the same direction. The result flies in the face of big bang theory, which rules out any such special or preferred direction. Another suggestion is that heat given off by the Milky Way's dusty disk has not been properly subtracted from the WMAP. "Certainly there are some sloppy papers where insufficient attention has been paid to the signals from the Milky Way," warns Bennett. Clearly, such a universe would flout a fundamental assumption of all big bang models: that the universe is the same in all places and in all directions. "People made these assumptions because, without them, it was impossible to simplify Einstein's equations enough to solve them for the universe," says Magueijo. And if those assumptions are wrong, it could be curtains for the standard model of cosmology. That may not be a bad thing, according to Magueijo. "The standard model is ugly and embarrassing," he says. "I hope it will soon come to breaking point."

"Big bang echoes through the universe"

Radiation from the big bang was first detected by accident in 1964, when two astronomers from Bell Laboratories in New Jersey were trying to measure faint radio waves coming from the outer parts of the Milky Way. The only interpretation that fits is that this cosmic background radiation must be coming from hot gas that filled the universe soon after the big bang. But the discovery raised a conundrum. The background radiation showed that the gas 300,000 years after the big bang was extremely smooth. Yet the universe today is very clumpy, with galaxies in clusters and filaments. Cosmologists believed that if they looked hard enough at the background radiation, they ought to be able to find some fluctuations in its temperature. This is what NASA's Cosmic Background Explorer satellite, COBE, was designed to find. The data from these instruments, as shown in the colour map, do indeed contain a lot of bright and dark blobs. Cosmologists have unanimously welcomed the news from COBE. "If COBE hadn't found the fluctuations, we would have had to rethink a lot of our basic theories - including general relativity," says Jasper Wall of the Royal Greenwich Observatory.

"Physicists attack cosmological model"

Now, however, a group of astrophysicists in the UK has found that this radiation - the microwave 'echo' of the big bang - may in fact have been modified or ‘corrupted’ as it passed through galaxy clusters on its way to Earth. The result could undermine previous evidence for both dark matter and energy.

"Astronomers Crunch Numbers, Universe Gets Bigger"

This finding implies that the Hubble constant, a number that astronomers rely on to calculate a host of factors -- including the size and age of the universe -- could be significantly off the mark as well. That means that the universe could be 15 percent bigger and 15 percent older than any previous calculations suggested. "Ten years ago, we didn't even know that dark energy existed. Now we know how much dark energy there is -- better than we know the Hubble constant, which has been around for almost 80 years," said Kris Stanek, associate professor of astronomy at Ohio State.

" 'Astounding' Findings Pin Down Age of Universe, Birth of First Stars"

The study finds that the early universe was 4 percent real matter in the form of atoms, about 23 percent unseen dark matter, and about 73 percent dark energy, a totally unknown and exotic force that causes the universe to accelerate at an ever-faster pace. Princeton University's David Spergel, co-investigator for MAP, said the new findings result from using the MAP data and running them against millions of computer simulations to look for matches of what the composition and geometry of the young cosmos must have been like. The process is as daunting as taking a picture of a 12-hour-old baby and morphing it into an image of a 50-year-old adult, said John Bahcall of the Institute for Advanced Study in Princeton, N.J. Bahcall said the observations and analysis were so precise that they must be believed. "Before the WMAP results, astronomers and physicists had put together a very implausible picture of our universe," Bahcall said. "It had a tiny amount of ordinary matter. It had a modest amount of dark matter, whatever that is. It had an overwhelming amount of dark energy, which is a strange beast. I have to confess I was very skeptical of this picture. But the WMAP results have convinced me." "We live in an implausible, crazy universe, but one whose defining characteristics we now know," Bahcall said.

"Big bang sound waves explain galaxy clustering"

The results back the standard models of a flat universe, dominated by dark matter and dark energy, that has been expanding since the rapid period of inflation just after the big bang. He adds that it dovetails with observations of the big bang's afterglow - called the cosmic microwave background radiation - which supports a universe composed of just 4% normal matter, 25% dark matter, and the rest dark energy. "The concordant picture we have of the universe is hanging together amazingly well," says Sir Martin Rees, The Astronomer Royal, Royal Society Research Professor at Cambridge University, UK. "In a way, it would be more exciting if we found a glaring inconsistency."

"Experts hoping to pin down gravity : Nobody knows what it is, but scientists at UW seek answers"

Though most of us think scientists have nailed down gravity thanks to Isaac Newton and Albert Einstein, it remains the most mysterious and least understood of the four basic forces of nature. Particle physicists have discovered that matter at the smallest level, the subatomic level, behaves very differently than either Newton or Einstein expected. This is the quantum realm of reality, in which everything is reduced to ultimate particles -- photons for light, electrons for electricity and the supposed graviton for gravity. Trouble is, nobody's ever detected a graviton and gravity refuses to behave in a way that quantum mechanics can explain.

"Quantum Leap in Understanding Gravity"

Gravity is relatively easy to observe in the everyday world of orbiting planets and falling apples. Yet even the smartest physicists don't know where gravity actually comes from.

"Newtonian Physics - All The Wrong Moves"

A team of planetary scientists and physicists has identified an unexplained sunward acceleration in the motions of the Pioneer 10, Pioneer 11 and Ulysses spacecraft. The accelerations are so persistent that they could be pointing to some relevant physics that's been overlooked in trying to explain the motions of bodies in the universe.

"The Problem with Gravity: New Mission Would Probe Strange Puzzle"

One candidate is dark matter. Another idea is that gravity tugs slightly harder at things farther away. That radical suggestion, if proved true, would force a modification of Einstein's general theory of relativity and might eliminate dark matter as a player. Yet one more exotic possibility: Dimensions exist beyond the four we know (three directions and time). No fancy theory in existence, however, properly explains the Pioneer data.

"Leaking Gravity May Explain Cosmic Puzzle"

Scientists have known since the 1920s that the universe is expanding. In the late 1990s, they realized that it is expanding at an ever-increasing pace. At a loss to explain the stunning discovery, cosmologists blamed it on dark energy. But the existence of dark energy is far from proven, and some researchers believe they and their colleagues simply don't understand gravity at larger scales.

"Modifying Gravity to Account for Dark Matter"

While it is the earliest-known force, gravity is still very much a mystery with theories still unconfirmed by astronomical observations in space. The 'problem' with the golden laws of Newton and Einstein is whilst they work very well on earth, they do not explain the motion of stars in galaxies and the bending of light accurately. Dr Benoit Famaey,of the Free University of Brussels, commented "It is possible that neither the modified gravity theory, nor the Dark Matter theory, as they are formulated today, will solve all the problems of galactic dynamics or cosmology. The truth could in principle lie in between, but it is very plausible that we are missing something fundamental about gravity, and that a radically new theoretical approach will be needed to solve all these problems."

"New Spin Source Could Offer Insight Into Gravity"

Many scientists today are working on unified theories, including String Theory, to explain universal forces. And, while many forces fit nicely into the Standard Model of particle physics, the characteristics of gravity, which are not very well understood, present a problem. "We have a situation in physics where we understand very well the quantum forces," Clive Speake, a scientist at the University of Birmingham in the UK, tells PhysOrg.com. "But gravity, as we understand it, is a problem."

"Physicists Find More Precise Gravity Number"

Newton's gravitational constant tells how much gravitational force there is between two masses - the Earth and sun, for instance - separated by a known distance. The gravitational constant along with the speed of light and Planck's constant are considered the three most fundamental and universal constants in nature. But while measurements of the other two constants have grown continually more precise through the years, the reverse has happened for the gravitational constant, called "Big G" in physics parlance. In fact, new attempts to measure Big G in the 1990s brought results widely different from the previously accepted figure. That prompted the National Institute of Standards committee that establishes the accepted value to determine that there actually was 12 times more uncertainty about the figure last year than in 1987. "That is a huge embarrassment for modern physics, where we think we know everything so well and other constants are defined to many, many digits," said Gundlach, a UW research associate physics professor. "Gravity is the most important large-scale interaction in the universe, there's no doubt about it," Gundlach said. "It is largely responsible for the fate of the universe. Yet it is relatively little understood."

"Big Bang afterglow reveals dark energy's repulsion"

"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," adds Albert Stebbins, at the Fermi National Accelerator Laboratory.

"Dark Energy May Be Vacuum"

Either the universe is made up of around 70% 'dark energy' (something that has a sort of anti-gravity) or our theory of gravity is flawed.

"Observatory Tries to Catch a Gravitational Wave"

Physicists also may uncover the mysterious "dark matter" that is believed to be all around us but has never been measured. Some think they might find gateways into extra dimensions.

"Superstrings could add gravitational cacophony to universe's chorus"

Albert Einstein theorized long ago that moving matter would warp the fabric of four-dimensional space-time, sending out ripples of gravity called gravitational waves. No one has observed such a phenomenon so far, but University of Washington researchers believe it is possible to detect such waves coming from strange wispy structures called cosmic superstrings.

"Scientists aim to unlock gravitational wave mysteries"

"We know that gravitational waves produced from cataclysmic astrophysical events are immensely powerful. We know that they play a significant role in the physics of the universe. But we have not been able to yet successfully detect and measure them." said Associate Professor Susan Scott, from the Physics Department at ANU.

"LIGO once again looking for gravitational waves"

LIGO researchers said they hope this run will lead to the first direct detection of gravitational radiation since Albert Einstein predicted its existence in 1916.

"Leading physicists convene in Tucson for conference on gravity"

More than three dozen leading physicists and astrophysicists will convene in Tucson for the conference, "Rethinking Gravity: from the Planck scale to the size of the Universe". "Scientists have understood for several decades that Einstein's theory of gravity, which describes our universe at astronomical scales, is incompatible with quantum field theories, which describe phenomena at atomic scales," physicist Dimitrios Psaltis of The University of Arizona, a conference organizer, said. "Despite numerous efforts, scientists have yet to come up with a satisfactory quantum theory of gravity.

"LSU professor resolves Einstein's twin paradox"

The twin paradox is known as one of the most enduring puzzles of modern-day physics. If one twin is placed on a space shuttle and travels near the speed of light while the remaining twin remains earthbound, the unmoved twin would have aged dramatically compared to his interstellar sibling, according to the paradox. But, in the previous scenario, the paradox is that the earthbound twin is the one who would be considered to be in motion – in relation to the sibling – and therefore should be the one aging more slowly. Einstein and other scientists have attempted to resolve this problem before, but none of the formulas they presented proved satisfactory.

"Did Einstein cheat?"

Van Flandern was hired to do some consulting work for the physics department at the University of Maryland on the global positioning system (GPS). According to him, the confusing "rigmarole" of relativity isn't needed to maintain the GPS, even though it clearly should be. Van Flandern also told the American Spectator's Washington correspondent, Tom Bethell, that he had reason to believe Einstein manipulated his field equations for one of his most momentous predictions: the advance of the perihelion of Mercury. It was a classic problem by the time Einstein came along, and his general theory of relativity solved it immediately. Too brilliantly, for some. Einstein knew that Mercury's observed perihelion was 43 arc seconds per century more than predicted by Newton's theory. "A lot of people say that he didn't know it, but he did," said Carroll Alley, a Princeton physics doctorate.

"Berkeley Lab Physicist Challenges Speed Of Gravity Claim"

Albert Einstein may have been right that gravity travels at the same speed as light but, contrary to a claim made earlier this year, the theory has not yet been proven. A scientist at Lawrence Berkeley National Laboratory says the announcement by two scientists, widely reported this past January, about the speed of gravity was wrong. Stuart Samuel, a participating scientist with the Theory Group of Berkeley Lab's Physics Division, in a paper published in Physical Review Letters, has demonstrated that an "ill-advised" assumption made in the earlier claim led to an unwarranted conclusion. "In effect, the experiment was measuring effects associated with the propagation of light, not the speed of gravity."

"Researchers extend Einstein's work"

"The original EPR work was undertaken by Albert Einstein in the 1930s and questioned the basis of what is today known as quantum mechanics," Dr Kheruntsyan said. "Einstein was never happy with certain aspects of quantum mechanics and the EPR paradox has been one of the most puzzling physics problems for the past 80 years. The essence of the paradox is that it suggested that classical concepts of physical reality were not applicable in the quantum domain.

"Was Einstein right when he said he was wrong?"

When in 1929 Edwin Hubble proved that the universe is in fact expanding, Einstein repudiated his cosmological constant, calling it "the greatest blunder of my life." Then, almost a century later, physicists resurrected the cosmological constant in a variant called dark energy. The requisite amount of dark energy is so difficult to reconcile with the known laws of nature that physicists have proposed all manner of exotic explanations, including new forces, new dimensions of spacetime, and new ultralight elementary particles. "Whether Einstein was right when he first introduced the cosmological constant, or whether he was right when he later refuted the idea will soon be tested by a new round of precision cosmological observations," said Fermilab's Kolb.

"The Genesis of Relativity"

Commenting on the publication of The Genesis of General Relativity, Bernard Schutz, director at the Max Planck Institute for Gravitational Physics said: "As a physicist living at a time when physicists are re-inventing gravity once again, I find this history not only fascinating and compelling but deeply relevant."

"Steering atoms toward better navigation, physicists test Newton and Einstein along the way"

Another mystery that ultracold atoms may help solve is Einstein's equivalence principle, which to date hasn't been proved or refuted. The implications are profound, says Stanford physicist Mark Kasevich. "If Einstein's equivalence principle doesn't hold, that means that we would have to rethink the law of physics at a very basic level."

"Dark Doings: Searching for signs of a force that may be everywhere . . . or nowhere"

Gia Dvali of New York University and his colleagues propose that gravity parts company with Einstein's theory because some of it leaks away into extra, hidden dimensions.

"Einstein In Need Of Update? Calculations Show The Speed Of Light Might Change"

In 1905, Einstein made major changes to laws of physics when he established his theory of relativity. Now Einstein's laws might also undergo significant changes. "This frequency-dependence of the speed of light changes drastically our view of the theory of relativity," says Nanopoulos, who chairs the Theoretical Physics Division of the Academy of Athens.

"100 years after E=mc2"

Even a century after Albert Einstein conjured up his world-changing equation, the nature of most of the universe still eludes us. For decades, relativity and quantum mechanics have provided the foundation for modern physics. Now this foundation is cracking. Enigmatic discoveries of dark matter a few decades ago and of dark energy a few years ago have thrown physics into turmoil.

"Physics' greatest endeavour is grinding to a halt"

Physics' greatest endeavour has ground to a halt. We are in "a period of utter confusion", said Nobel laureate David Gross, summing up last week's prestigious Solvay conference on the quantum structure of space and time. That is worrying because the topic is central to finding a "theory of everything" that will describe every force and particle in nature. Einstein's relativity, which reigned supreme for a century, is a flawed basis for such a theory.

         
        
STRING THEORY ARTICLE EXCERPTS

"Physicists to mark 20th anniversary of first string theory revolution"

Physicists are anxious because string theory has become popular but it is not yet grounded in experiment. Mathematicians, meanwhile, are nervous because it produces new mathematical ideas that aren't backed up by formal mathematical proofs.

"Has string theory tied up better ideas in physics?"

String theory isn't any more wrong than preons, twistor theory, dynamical triangulations, or other physics fads. But in those cases, physicists saw the writing on the wall and moved on. Not so in string theory. "What is strange is that string theory has survived past the point where it should have been clear that it wouldn't work," says Peter Woit of Columbia University.

"No sign yet of extra dimensions"

"It is possible that some day string theory will be understood well enough to make very precise predictions about new forces such those as we seek. Until then, it's a fishin' expedition," says John Price at the University of Colorado in Boulder.

"Yale Scientist Says Clues To String Theory May Be Visible In Big Bang Aftermath"

String theory attempts to unify the physics of the large (gravity) and the small (the atom). These are now described by two theories, general relativity and quantum theory, both of which are likely to be incomplete. Critics have disdained string theory as a "philosophy" that cannot be tested. Easther stressed it is a long shot that string theory might leave measurable effects on the microwave background by subtly changing the pattern of hot and cold spots.

"The Inelegant Universe"

In this grim assessment, string theory--an attempt to weave together general relativity and quantum mechanics--is not just untested but untestable, incapable of ever making predictions that can be experimentally checked. With no means to verify its truth, superstring theory, in the words of Burton Richter, director emeritus of the Stanford Linear Accelerator Center, may turn out to be "a kind of metaphysical wonderland." The counterargument, of course, is that string theory is dominant because the majority of theorists sense that it is the most promising approach--that the vision of oscillating strings singing the cosmic harmonies is so beautiful that it has to be true. But even that virtue is being called into question. "Once one starts learning the details of ten-dimensional superstring theory, anomaly cancellation, Calabi-Yau spaces, etc., one realizes that a vibrating string and its musical notes have only a poetic relationship to the real thing at issue," writes Peter Woit, a lecturer in mathematics at Columbia University, in Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law. The contortions required to hide away the seemingly nonexistent extra dimensions have resulted in structures Woit finds "exceedingly complex" and "exceedingly ugly." With no proper theory in sight, they assert, it is time to move on. "The one thing everyone who cares about fundamental physics seems to agree on is that new ideas are needed," Smolin writes. "We are missing something big." Unable to fit the four forces of nature under the same roof, a few theorists in the 1970s began adding extra rooms, but there were an infinite number of ways to do this. The despair turned to excitement when the possibilities were reduced to five and to exhilaration when, in the mid-1990s, the five were funneled into something called M Theory, which promised to be the one true way. That was six years ago, and to hear Smolin and Woit tell it, the field is back to square one: recent research suggests that there are, in fact, some 10500 perfectly good M theories, each describing a different physics. The theory of everything, as Smolin puts it, has become a theory of anything.

"String Theory? Knot!"

But string theory has one teensy-weensy problem; it has, as yet, no testable hypothesis. It's this bit of scientific sacrilege that makes it all too easy for critics of the theory to lambaste and lampoon it. One such critic is Peter Woit, lecturer in the Mathematics Department of Columbia University, claiming that without a testable hypothesis, string theory is no better than religious dogma. Woit suggests that string theorists, starved of anything tangible to go on, seem to be appropriating known physics to suit their own ends. According to Woit, string theorists are offering dramatic and outrageous rhetoric, rather than science, to support their case.

"Nobel laureate admits string theory is in trouble"

"We don’t know what we are talking about. Many of us believed that string theory was a very dramatic break with our previous notions of quantum theory," he said. "But now we learn that string theory, well, is not that much of a break." -- Nobel laureate David Gross at the 23rd Solvay Conference in Physics in Brussels, Belgium.

"Can String Theory Explain Dark Energy?"

Quantum field theory allows for the existence of such a universal tendency. Unfortunately, its prediction for the value of the density of dark energy (a parameter referred to as the cosmological constant) is some 120 orders of magnitude larger than the observed value.

"Quantum vibe"

String theory may go the way of theories of the luminiferous ether, a 19th century explanation of light that Einstein and others washed away in the early decades of the 20th. String theorists' life work hangs on a series of suppositions, and while their daily work is to strengthen those suppositions by both fleshing them out and looking relentlessly for holes, there is a chance that the whole enterprise will come crashing down.

"Learning the alphabet of particles"

As Greene points out in "The Elegant Universe," these theories clash when applied to the same phenomena. For instance, when equations from quantum theory and general relativity are combined to describe the behavior of a black hole, they provide answers that turn out to be meaningless. Greene thinks this means one or both theories must have something wrong. But string theory introduces some very bizarre ideas of its own. It says that the universe must have 10 dimensions of space and time, instead of the three dimensions of space and the one dimension of time that we know. Physicists feel they're on the right track when they find a mathematical description that is both simple and universal; other physicists question whether string theory has a basis in the physical world or is just mathematical abstraction. Perhaps the most revolutionary idea of string theory is that it defies the scientific tradition of developing a hypothesis to be tested by experiment.

        
     
HIGGS 'GOD PARTICLE' ARTICLE EXCERPTS

"Underground search for 'God particle' "

The Higgs is nicknamed the God particle because of its importance to the Standard Model, the theory devised to explain how sub-atomic particles interact with each other. The 16 particles that make up this model (12 matter particles and 4 force carrier particles) would have no mass if considered alone. So another particle - the Higgs boson - is postulated to exist to account for this omission.

"Physicists Closing In On Mysterious Missing Particle That Gives Matter Mass"

So far, the Higgs-boson only exists in mathematical formulas and has stumped physicists since it was theorized by Peter Higgs in 1964.

"Scientists close in on elusive particle"

Scientists may have spotted the most sought-after prize in particle physics, the elusive Higgs particle. Hundreds of particle physicists heard that all four experiments at the Large Electron Positron (Lep) collider had found the first hints of the elusive Higgs boson. The atom-smasher that produced these events is scheduled to close down in a few weeks, meaning that researchers have little time to confirm their discovery. The committee that decides Cern's research programme will decide next week whether the Lep accelerator will continue running until December. Particle physicists nervously await its decision.

"No sign of the Higgs boson"

The legendary particle that physicists thought explained why matter has mass probably does not exist. So say researchers who have spent a year analysing data from the LEP accelerator at the CERN nuclear physics lab near Geneva. The elusive Higgs boson is so central to the standard model - the theory on which physicists base their whole understanding of matter - that it has been dubbed the "God particle". If there is no Higgs, they will be left totally unable to explain mass. Higgs’ work triggered a 30-year quest to find the Higgs boson. This is what members of the Electroweak Working Group at CERN were doing for the 5 years until LEP (the Large Electron Positron Collider) closed down last year. Since then they've been sifting through the data they gathered--and found nothing. For many it's a big disappointment, because last year researchers from another group at LEP claimed they had found the Higgs. Their announcement came shortly before LEP was due to close, and it won them one month's extra time on LEP. But they later admitted to having botched their calculations in the heat of the moment. This isn't the first bad news for the standard model. In February, researchers at Brookhaven National Laboratory in New York ruffled feathers by saying that the magnetic moment of the muon was different to the predicted value. But the latest blow is more serious. The non-appearance of a key particle would signal the end of large parts of the standard model. The problem for physicists is that without the Higgs particle they don't have a viable theory of matter. "There is nothing remotely as plausible or compelling to replace it," says Wilczek. For physicists who have spent years trying to find the Higgs, admitting it could be fantasy is a huge and difficult step.

" 'God particle' may not exist"

But the Cern researchers have told New Scientist magazine that studies in its giant accelerator which should have shown up the presence of the Higgs found absolutely nothing - and this could mean particle physics having to revisit some of its most cherished ideas. If there is no Higgs, science will be left totally unable to explain mass. Just before the Lep was due to be closed down and scrapped, one team declared last year that it had seen tantalizing "shadows" of something which could be the sought after particle. The Lep got a one-month reprieve for follow-up work and was then closed. Since then, researchers at Cern have been sifting their data. Their conclusion is that there was nothing in the data at all to suggest the Higgs is out there. Cern's David Plane is also still hopeful. "It's just at a higher energy than we're sensitive to," he told the magazine. The Lep is making way for a bigger facility, the Large Hadron Collider, which is due to start crunching particles at even higher energies in 2007.

"Dark matter and 'God particle' within reach"

The boundaries of knowledge in particle physics look set to be broken soon with scientists around the globe locked in a multi-billion-dollar race to solve two great mysteries. Last week, an international consortium stepped up the pace by announcing in Beijing, China, a design for the world's most expensive atom smasher - the US$6.7 billion International Linear Collider (ILC). If the Higgs exists, it would fill a worrying gap in the Standard Model, the century-old notional structure for describing the fundamental nature of matter. But if the Higgs doesn't exist, it will be back to the drawing board.

"Physics failure could mean success"

It might sound like a bit of a surprise, but a handful of scientists participating in the $4-billion international experiment to discover the Higgs boson, the Holy Grail of particle physics, hope the effort fails. "We expect to see the Standard Model Higgs boson and/or some new physics. If we don’t see the Higgs boson, then the Standard Model is wrong. Either way, the LHC guarantees a discovery," says Dr. James Pinfold, a University of Alberta physics professor who is leading an international team of scientists in a separate experiment at CERN. Pinfold himself suspects the Standard Model is wrong.

"Fermilab data hint at Higgs boson"

Physicists analyzing data taken by the HyperCP experiment at Fermilab in the US claim it may have glimpsed the first Higgs boson -- the particle many think is responsible for all mass in the universe. However, for their claim to be correct our current 30-year-old Standard Model of particle physics would have to be set aside in favour of an alternative "supersymmetric" model. The great triumph of the Standard Model is that it unites two of the fundamental forces – the weak and electromagnetic force – into a single, symmetric "electroweak" force at high energies. But at low energies, a symmetric electroweak theory would imply that particles have no mass, which is clearly wrong. Theoretical physicists say Fermilab might have got there first – that is, if we are prepared to consider an "extension" to the Standard Model. That experiment appeared to show three "events" in which a sigma-plus particle decays into a proton and a muon-antimuon pair. Although just three events would not normally be regarded as significant, German Valencia from Iowa State University in the US and colleagues suggest that the events could be interpreted as evidence for a new particle. The particle does not fit into the current Standard Model. However, it could be explained using the "next-to-minimal supersymmetric standard model" (NMSSM). This model is one of several "supersymmetric" models proposing twice or more the number of particles. In the NMSSM there are seven Higgs bosons. This is not the first time physicists have laid claim to a Higgs as part of an alternative supersymmetric theory. Earlier this year, John Conway and Tommaso Dorigo suggested that a 160-GeV "bump" in Fermilab data could have been one of five Higgs bosons in the more favoured "minimal supersymmetric standard model" (MSSM).

"Experts home in on 'God particle' "

The hypothetical Higgs boson, often dubbed the "God particle", is fundamental to our understanding of the Universe but has yet to be detected. "And if we don't find it, it is going to be back to the drawing board for particle physics." Dr Mark Lancaster, UK spokesman for the Collider Detector at Fermilab

"The Higgs particle just got lighter"

The Higgs particle just got a bit lighter and the race to find it a little tighter, thanks to the most precise measurement yet of the mass of the W boson. Based on this, the team recalculated the predicted mass of the yet-to-be-found Higgs boson, the particle thought to give all other particles their mass. If the Tevatron or the LHC do not find the Higgs at these energies, physicists will be forced to look beyond the Standard Model of particle physics.

"Racing to the 'God Particle' "

"One thing we expect the Higgs to open up is the question of supersymmetry," says John Womersley, co-spokesman of the D0 experiment at Fermilab. Supersymmetry is a relationship between the particles of matter and the forces of the universe. Mathematically, it's beautiful. Not one piece of direct experimental data really supports it yet. Finding a Higgs in the place we expect would be a piece of evidence. Not finding it would be a big problem for the advocates of this idea. "What would shake the foundation of physics much more than finding the Higgs would be a definitive 'ruling it out.' That would upset all of our conceptions about how the universe works."

"Higgs boson: Glimpses of the God particle"

If the blips in the debris of the Tevatron particle smasher really are signs of the Higgs boson then it's not what we expected. It might mean that it's time to replace the standard model with a more complex picture of the universe. If the Higgs is discovered, the standard model could justifiably claim to be the theory that unifies everything except gravity. But the model is creaking. Take the Higgs itself. The standard model tightly links the masses of the Higgs, the W boson, and the top quark. Experiments at the LEP collider at CERN have homed in on the mass of the W boson and the top quark. If you use these measurements to calculate the mass range of the Higgs, and compare it with the standard model's predictions, you run into trouble. "The best measurements of the W and top quark mass don't agree well with the standard model," says Conway, who is based at the University of California, Davis.

GENERAL PHYSICS ARTICLE EXCERPTS

" 'Theory of everything' tying researchers up in knots"

The most celebrated theory in modern physics faces increasing attacks from skeptics who fear it has lured a generation of researchers down an intellectual dead end. Skeptics suggest it's the latest sign of how string theorists try to colorfully camouflage the theory's flaws, like "a 50-year-old woman wearing way too much lipstick," jokes Robert B. Laughlin, a Nobel Prize-winning physicist at Stanford. "People have been changing string theory in wild ways because it has never worked."

"Can the Laws of Physics Be Unified?"

As lovely as the Standard Model's description is, it is in pieces, and some of those pieces--those that describe gravity--are missing. A unified theory should have observable consequences. For example, if the strong force truly is the same as the electroweak force, then protons might not be truly stable; once in a long while, they should decay spontaneously. Despite many searches, nobody has spotted a proton decay, nor has anyone sighted any particles predicted by some symmetry-enhancing modifications to the Standard Model, such as supersymmetry. Worse yet, even such a unified theory can't be complete--as long as it ignores gravity. Gravity is a troublesome force. The theory that describes it, general relativity, assumes that space and time are smooth and continuous, whereas the underlying quantum physics that governs subatomic particles and forces is inherently discontinuous and jumpy. Gravity clashes with quantum theory so badly that nobody has come up with a convincing way to build a single theory that includes all the particles, the strong and electroweak forces, and gravity all in one big bundle. But physicists do have some leads. Perhaps the most promising is superstring theory. Or it may be that the struggle to unify all the forces and particles is a fool's quest.

"Physicists say universe evolution favored three and seven dimensions"

Physicists who work with a concept called string theory envision our universe as an eerie place with at least nine spatial dimensions, six of them hidden from us, perhaps curled up in some way so they are undetectable. The big question is why we experience the universe in only three spatial dimensions instead of four, or six, or nine. Two theoretical researchers from the University of Washington and Harvard University think they might have found the answer. They believe the way our universe started and then diluted as it expanded -- what they call the relaxation principle -- favored formation of three- and seven-dimensional realities. The one we happen to experience has three dimensions. "That's what comes out when you do the math," said Andreas Karch, a University of Washington assistant professor of physics. "There are regions that feel 3D. There are regions that feel 5D. There are regions that feel 9D. These extra dimensions are infinitely large. We just happen to be in a place that feels 3D to us," he said. "We know there are people in our three-brane existence. In this case we will assume there are people somewhere nearby in a seven-brane existence. The people in the three-brane would have a far more interesting world, with more complex structures." Karch said they hope the work will spark extensive scientific exploration of many other questions involving string theory, extra dimensions and the evolution of the cosmos.

"What's Wrong with Quantum Mechanics?"

Albert Einstein never really liked quantum mechanics. In 1935, he and two colleagues argued in the Physical Review that the theory was missing something essential. Although the argument was essentially disproved later, it still leaves difficult questions unresolved, if largely ignored, by most working physicists. Einstein, Boris Podolsky, and Nathan Rosen, of the Institute for Advanced Study in Princeton, concluded that quantum mechanics was incomplete … Einstein found Bohr's reply unconvincing, since it carefully avoided any attempt to say what was going on behind the scenes. Einstein, Podolsky and Rosen used "unequivocally good reasoning," says Abner Shimony of Boston College. The flaw is that quantum mechanics has an element of non-locality--a subtle connection between the two particles that persists even after they separate. But Bohr as much as Einstein, Shimony believes, would not have welcomed non-locality, whose implications for our understanding of the fundamental nature of the physical world remain obscure.

"Speed Of Light May Not Be Constant, Physicist Suggests"

A University of Toronto professor believes that one of the most sacrosanct rules of 20th-century science -- that the speed of light has always been the same - is wrong. Ever since Einstein proposed his special theory of relativity in 1905, physicists have accepted as a fundamental principle that the speed of light is a constant and that nothing has, or can, travel faster. John Moffat of the physics department disagrees. Recent theory and observations about the origins of the universe would appear to back up his belief. For instance, theories of the origin of the universe -- the "Big Bang"- suggest that very early in the universe's development, its edges were farther apart than light, moving at a constant speed, could possibly have travelled in that time. To explain this, scientists have focused on strange, unknown and as-yet-undiscovered forms of matter that produce gravity that repulses objects.

"Speed of light may have changed recently"

The speed of light, one of the most sacrosanct of the universal physical constants, may have been lower as recently as two billion years ago - and not in some far corner of the universe, but right here on Earth. The controversial finding is turning up the heat on an already simmering debate, especially since it is based on re-analysis of old data that has long been used to argue for exactly the opposite: the constancy of the speed of light and other constants. A varying speed of light contradicts Einstein's theory of relativity, and would undermine much of traditional physics. But some physicists believe it would elegantly explain puzzling cosmological phenomena such as the nearly uniform temperature of the universe. It might also support string theories that predict extra spatial dimensions. It would be a boost to versions of string theory in which extra dimensions change the constants of nature at some places in space-time. Variable "constants" would also open the door to theories that used to be off limits, such as those which break the laws of conservation of energy.

"Light So Fast It Actually Goes Backwards"

In the past few years, scientists have found ways to make light go both faster and slower than its usual speed, but now researchers have gone one step further: pushing light into reverse. As if to defy common sense, the backward-moving pulse of light travels faster than light. "I've had some of the world's experts scratching their heads over this one," said lead author Robert Boyd of the University of Rochester. "I know this all sounds weird, but this is the way the world works," Boyd said. The problem with the results is they seem to violate Einstein's tenet that nothing can travel faster than light – not even light.

"The Enduring Mystery of Light"

Because it is so many things, defining light is a bit of a philosophical quandary. What ties together microwaves, X-rays and the colors of the rainbow is that they are all waves—electromagnetic waves to be exact. But waves are not the whole story. Light is composed of particles called photons. The classic example of particleness is the photoelectric effect, in which light hitting a metal sheet causes electrons to fly out of the surface. Surprisingly, light longer than a certain wavelength cannot liberate electrons, no matter how bright the source is. A strict wave theory of light cannot explain this wavelength threshold. Albert Einstein deciphered the mystery in 1905 by assuming that particles of light smacked into the electrons. Despite this success, the particle theory never replaced the wave theory. We therefore have to live with light being both a particle and a wave—sometimes acting as hard as a rock, sometimes as soft as a ripple. Instead of worrying about what light is, it might be better to concentrate on what light does. All this shows that light wears many different hats in its manipulation of matter. It is perhaps fitting then that light's true identity—wave or particle—is unanswerable.

"Shadowy T-rays: Hunting Tumors and Exploring the Universe"

Between microwaves and X-rays, in the least explored region of the spectrum, lie T-rays, or terahertz radiation, the most common form of radiation in the universe. If you've never heard of T-rays, it's because scientists have had trouble harnessing them. Although the first scientific paper on the subject was published in the 1890's on the first page of the first issue of the journal Physical Review, the challenges of generating, detecting, and manipulating terahertz radiation have hindered the technology's research and development. "At this point the technology is very young," said electrical engineer Daniel Mittleman, of Rice University's T-ray lab. "Terahertz is now where X-rays were in 1905," ten years after Wilhelm Conrad Rontgen discovered X-rays.

"New particle baffles physicists"

To their surprise, they found that their new meson had a lifetime that was three times longer than that of lighter mesons. Normally, the half-life of a meson gets shorter as the mass increases. Moreover, the new meson decayed into another meson known as the eta meson six times more often than predicted by theory. "It suggests that some intriguing new dynamical aspect of the strong force is at work, and it opens the door for many future explorations, at Fermilab and around the world." said Christopher Hill, a theorist at Fermilab. The new meson is the latest in a list of recent surprising discoveries in particle physics.

"Mystery Particle May Hold Clues To Universe"

The University team of 14 is part of a group of 300 physicists from 13 countries known as the 'Belle collaboration'. They have discovered a sub-atomic particle that they are having difficulty explaining and difficulty fitting with any current theory that attempts to describe matter. "It could mean some of the standard and accepted theories on matter will need to be modified to incorporate some new physics," says University of Melbourne doctoral student in physics and Belle team member, Mr Craig Everton. The sub-atomic particle they believe could be a meson. This 'mystery meson' weighs about the same as a single atom of helium. The Belle discovery was recently confirmed by researchers with the CDF (Collider Detector at Fermilab) experiment at the Fermi National Accelerator Laboratory in Illinois, home of the Tevatron, the world's largest electron collider.

" 'Milestone' Study Challenges Basic Laws of Physics, Universe"

An international team of researchers announced Thursday findings in the subatomic world that, if proven accurate, could upset a basic set of laws that scientists use to describe the physical world. The potential change in thinking would force cosmologists to reconsider the origin, evolution and daily operation of the universe. Brad Keister, director of the nuclear physics program at the National Science Foundation, said the finding, if it holds up, will change how cosmologists view the evolution of the universe back to and including the Big Bang, though this basic theory of how everything began would not necessarily be tossed out. The finding could mean that new and strange types of physics might be possible. These companion particles, while never before seen, would not surprise most theorists, who have long suspected that "empty" space is actually a sea of virtual particles that appear and disappear almost instantaneously. These particles, if found to exist, might account for some or all of the missing mass in the universe. The scientists involved in the study -- 68 researchers from 11 institutions in the United States, Russia, Japan and Germany -- agree that more research is needed to confirm the work.

"Supercomputers Help Physicists Understand A Force Of Nature"

The strong nuclear force that binds these particles together, which is also called quantum chromodynamics, is one of the four basic forces of nature, along with gravity, electromagnetism and the weak force. The strong nuclear force is very powerful at short ranges, binding quarks and gluons into neutrons and protons at the core of atoms. The basic equations that describe the nuclear force have been known since the mid 1970s, and were the subject of the 2004 Nobel Prize in physics. But physicists still know very little of how the force described by these equations binds protons and neutrons into the nuclei of atoms.

"Scientists Dubious of Quantum Claims"

Quantum computing is such an elusive goal that even the company claiming to have the "world's first commercial quantum computer" acknowledged it isn't entirely sure the machine is performing true quantum calculations.

"Picking on Einstein"

But scientists today have reason to think that even Einstein's theory isn't the whole story; another revolution seems inevitable. The reason for doubt is that Einstein's theory is incompatible with quantum mechanics, another pillar of modern physics that describes the odd world of subatomic particles. When the theories are used together, sometimes, their combined equations produce nonsense. This leads scientists to believe that current theories will eventually be replaced by a single, elegant theory that explains all physical phenomena from the subatomic to the cosmic, the so-called "Theory of Everything."

"Expert says universe hard to understand"

London delegates to a global conference on the future have been warned that our universe may be just "too queer" to understand.