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Harvard University researchers have halted a pulse of laser light in its tracks and revived it a fraction of a millimeter away. Here's the twist: they stopped it in a cloud of supercold sodium atoms, known as a Bose-Einstein condensate (BEC), and then restarted it in a second, distinct BEC as though the pulse had spookily jumped between the two locations. "It's odd," says atomic physicist Lene Hau, the team's leader. "We can actually revive the light pulse and send it back on its way as if nothing had happened." ~snip~ BEC clouds are prized because their atoms' delicate quantum...

Nate Merrill of Old Orchard Beach was browsing through a New Yorker magazine recently when he noticed a cartoon of a man walking by a joint named "Harvey's Place." A sign in the window advertised an evening discussion titled: "Is String Theory (expletive)?" Funny? Perhaps. Offensive? Merrill thought so. "I said I think the New Yorker has taken a step back," he said. "Five years ago, there's no way they would have published cartoons like that." There are times in life when a person needs to say something a little stronger than "Oh, fudge." And "fiddlesticks" doesn't pack quite the...

A new study demonstrates that the shapes of extra dimensions can be "seen" by deciphering their influence on cosmic energy released by the violent birth of the universe 13 billion years ago. The method, published today (Feb. 2) in Physical Review Letters, provides evidence that physicists can use experimental data to discern the nature of these elusive dimensions -- the existence of which is a critical but as yet unproven element of string theory, the leading contender for a unified "theory of everything." ...According to string theory mathematics, the extra dimensions could adopt any of tens of thousands of possible...

In 2006, string theorist Allan Adams of MIT in Cambridge, US, and others offered a more promising check. They showed that some particle collisions could reveal whether certain fundamental assumptions underlying string theory are wrong. Now, another team has shown that the energies needed to reveal such effects are achievable at the LHC, which is being built in Geneva, Switzerland. The team was led by Jacques Distler of the University of Texas in Austin, US. One of string theory's assumptions comes from Einstein's theory of relativity – that the speed of light is the same for all observers, a principle...

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. The cyclic model proposed by Dr. Paul Frampton, Louis J. Rubin Jr. distinguished professor of physics in UNC's College of Arts & Sciences, and co-author Lauris Baum, a UNC graduate student in physics, has four key parts: expansion, turnaround, contraction and bounce. During expansion, dark energy -- the unknown force causing the universe to expand at an accelerating rate -- pushes and pushes until...

The subject of the debate was the Anthropic Principle, which states that the observable universe has to be as it is in order to support life. That is, the fundamental constants of the universe are precisely chosen such that if they were tweaked only slightly, then life, the earth or even our galaxy would not have formed. Thus, these values are as we observe them only because we are here to observe them in the first place. Paul Davies, director of Beyond: The Institute for Fundamental Concepts in Physics at Arizona State University, was the first to speak, arguing that...

Scientists' theories such as Einstein's relativity and string theory mock up mathematical worlds where linear and multidimensional time travel are a reality... String theory is an attempt to bring quantum physics and relativity together, according to Blondin. String theory supports the view that the universe is made of multiple dimensions and opening a porthole between these dimensions could cross time barriers... These examples focus mainly on a one-dimensional travel experience, meaning a person can only travel forward and backward in one pathway. But with the introduction of string theory became the possibility of a multidimensional universe and multidimensional time travel.

For decades, scientists have taken issue with "string theory"-a theory of the universe which contends that the fundamental forces and matter of nature can be reduced to tiny one-dimensional filaments called strings-because it does not make predictions that can be tested. But researchers at the University of California, San Diego, Carnegie Mellon University, and The University of Texas at Austin have now developed an important test for this controversial "theory of everything." Described in a paper that will appear in the January 26 issue of the journal Physical Review Letters L, their test involves measurements of how elusive high-energy particles...

As exciting as the news of our immanent destruction is, science still has yet to fully explain how all of this works. According to the "slimy string theory" of modern physics, subatomic particles begin as a oozy, mucus-like substance and can eventually take recognizable forms of matter like solids, liquids, and gasses but only for a while, about four to eight billion years. With the calculations from the Doomsday Clock group, it now appears that our time is just about up. As soon as their famous clock strikes midnight, all those tiny elemental bits will return to their original state,...

The sun, it turns out, isn't yellow. The earth isn't a perfect sphere. Asteroids can and do have moons. Saturn will soon (in 100 million years, anyway) be shorn of its rings. The equinoxes do not consist of exactly 12 hours of daylight and 12 hours of darkness. Intergalactic space is so empty of matter that a random cube of it, "200,000 kilometers on a side, contains about the same number of atoms as the air that fills the usable volume of your refrigerator." ...Dark energy, dark matter, the failures of string theory, the origins of life -- Tyson happily...

String theorists state that electrons, photons, protons, and all other particles are not zero-dimensional point-like objects (which form the basis of the Standard Model) but rather tiny one-dimensional extended objects that behave like strings. A group of strings vibrate at a specific resonant frequency -- similar to the movement of strings to produce different sounds on musical instruments such as the violin and guitar -- depending on what type of particle they are, such as electron, photon, proton, and so forth. Over the years, string theorists have not generated any experimental data based on fundamental physical law that proves or...

Researchers found that the same law governing the gravitational pull between planets continues to work when objects are separated by as little as 56 micrometers. The finding rules out extra dimensions of 44 micrometers or larger, they report in this week's Physical Review Letters. Discovering extra dimensions with the relatively huge size of a few micrometers would offer spectacular confirmation for string theory, the still unproved body of equations that may unify gravity with the normally incompatible realm of quantum physics. "Even though we haven't seen anything, these results put boundaries on what people can legitimately propose," says experimental physicist...

Particle physics is in the doldrums. Since 1974 it has not made any major advance except to add to the particle zoo and to tweak the Standard Model. String theory has claimed the attention many young physicists, eager for both fresh challenges and new intellectual adventures. But save for a daunting set of equations, string theory to this day is devoid of even a scintilla of direct observational evidence. For these reasons, a lot is riding on the Large Hadron Collider (LHC) that was completed last year and will begin full operation this year... It’s the world’s biggest particle accelerator...

Ramanath Cowsik, a Washington University physicist, will poke and prod at some of the most daunting problems remaining in physics: What is causing the universe to fly apart, faster and faster each year?Why is gravity so weak and so different from the other basic forces in the universe? And what is the true shape of the universe? In an era of big science -- billion-dollar space telescopes and atom smashers -- Cowsik's approach is refreshingly small. The apparatus, called a torsion balance, is cheap and based on a centuries-old idea. He says the torsion balance will cost about $100,000. When...

The poster child for dark matter, which got a lot of attention last summer, is the Bullet Cluster of galaxies... What's less well known is that the smaller of the two colliding clusters is a cluster in a hurry, zipping along at 4700 kilometers per second... Farrar... and her graduate student Rachael Rosen estimated a few months ago that gravity should have accelerated the cluster to maybe 3000 km/s. Even if the cluster had an improbable combination of elongated shape, high initial velocity, and special viewing geometry, it should move no faster than 3400 km/s. Farrar concluded that some new...

Many physicists consider a complex and sometimes-controversial premise called string theory to be a leading candidate to unify their understanding of the four basic forces of nature -- gravity, electromagnetic, weak and strong. String theory is sometimes criticized for being untestable or even unscientific, but some versions now predict an exotic behavior with observable effects: the formation of cosmic superstrings, narrow tubes of energy left from the beginning of the universe that have been stretched to enormous lengths by the expansion of the universe, said UW cosmologist Craig Hogan... "They're so light that they can't have any effect on cosmic...

At the time when Hamilton and Friedan discovered the Ricci flow, there wasn't much communication between physicists and mathematicians, Morrison says. "They arrived at this notion completely independently." But the communication between the fields has partially improved in recent years, he says. "In Perelman's first preprint, he seems really inspired by the occurrence." And since Perelman's proof appeared, there has been renewed interest to investigate the applications of the Ricci flow to string theory, he says. Perelman's proof was the first mathematical discovery to be recognized by Science magazine as the Breakthrough of the Year.

Throughout history scientists from Galileo to Andrei Sakharov have been persecuted for challenging the orthodoxy of their societies. But in The Scientist as Rebel, Freeman Dyson advocates rebellion of a broader kind. Science, the theoretical physicist writes, should rebel "against poverty and ugliness and militarism and economic injustice." Benjamin Franklin is Dyson's ideal of the scientific rebel, one who embodied "thoughtful rebellion, driven by reason and calculation more than by passion and hatred." If science ever stops rebelling against authority, Dyson insists, it won't deserve to be pursued by our brightest children... Dyson also rebels against the idea that scientists...

I recently completed writing a high school/college-level history of physics in the 20th century. It was a great opportunity to catch up on developments in the field. The biggest surprise turned out to be historical. For the first three-quarters of the century, progress in both theoretical and experimental physics steadily transformed our fundamental understanding of the physical universe. Then a multidimensional mathematical approach called string theory caught fire. To many physicists, it appeared to be the path to their science's holy grail, the "grand unification" of all known forces and fundamental particles into a single theory. But, instead of continuing...

Using Einstein's recorded utterances, Carrière crafts a loving if slightly idealized portrait of a great man. (Einstein's failed marriage and his indifferent parenting are alluded to only offhandedly, and there is no mention of what his otherworldliness must have cost those around him.) Because of his search for understanding and his recognition of the human being's place in the cosmos, we find Einstein still very much a needed figure for our times, with nationalism still virulent, religious conflict occupying more and more space in the newspapers, and the awful prospect of atomic weapons in the hands of zealots.