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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.

Consider how differently the public treats physics and economics. Physicists can say that this week they think the universe has eleven dimensions, three of which are purple, and two of which are twisted clockwise, and reporters will quote them unskeptically, saying "Isn't that cool!" But if economists say, as they have for centuries, that a minimum wage raises unemployment, reporters treat them skeptically and feel they need to find a contrary quote to "balance" their story.

For many years, I’ve been a big fan of string theory, also known as superstring theory. A year and a half ago, I discovered a fascinating television program on PBS Nova, The Elegant Universe, that changed the way I looked at life around me... The show was split into 3-1 hour segments, in which I only caught the last 2; I found myself frantically calling PBS to obtain the DVD. It was like no other science program that I had ever watched; It was creative, had stunning visual effects and examples, and kept my full attention throughout the entire 3...

A U.S. high school senior has won the grand prize scholarship in the Siemens Competition in Math, Science and Technology for his research in mathematics. Dmitry Vaintrob of South Eugene High School in Eugene, Ore., was named Monday the winner of the $100,000 top math prize scholarship for his research in an abstract new area of mathematics called string topology. Seniors Scott Molony, Steven Arcangeli and Scott Horton from Oak Ridge High School in Oak Ridge, Tenn., will share the $100,000 prize in the team category for developing a technique that might help scientists engineer biofuel from plants. The awards...

Many scientists never liked it anyway, and now Glenn Starkman from Oxford/Case Western and Roberto Trotta from Oxford show that too many details—and too many unknowns—mean that anthropic reasoning gives inconsistent values of the cosmological constant, some that are far from current estimates. In their recent paper, "Why Anthropic Reasoning Cannot Predict Lambda" (Physical Review Letters), Starkman and Trotta find that different ways of defining the probability of observers in different universes leads to vastly different predictions of the cosmological constant... According to the Anthropic Principle, the fact that we are here to observe the universe explains why the laws...

According to string theory, the universe is composed of tiny, vibrating strings rather than point-like particles. Depending on a particular string's mode of vibration, it would take on the characteristics of some particular particle -- an electron, for example, or a photon of light... In its latest incarnation it is known as "M-Theory," in which one-dimensional strings are replaced by higher-dimensional membranes, or "branes" for short. Although some of these branes may be microscopic, others could be large, or perhaps even infinite -- with important implications for cosmology... While string theory begins with matter, loop quantum gravity begins with space...

In the time-travel thriller directed by Tony Scott, Washington stars as a federal agent investigating the bombing of a ferryboat full of sailors. Intrigued by one of the terrorist's victims (Paula Patton), he gets a chance to alter the day's tragic outcome after being recruited by a covert government surveillance lab capable of bending time and space. "Thank God I didn't have to play a scientist," Washington says, laughing. "They sent me some stuff on black hole theory by that scientist in the wheelchair -- Stephen Hawking -- and I didn't know what they're talking about." In the movie, researchers...

The existence of black holes is perhaps the most fascinating prediction of Einstein's Theory of General Relativity. When any mass, such as a star, becomes more compact than a certain limit, its own gravity becomes so strong that the object collapses to a singular point, a black hole. In the popular mind, this immense gravity well is a place where strange things happen. And now, a Center for Astrophysics-led team has measured a black hole spinning so rapidly - turning more than 950 times per second - that it pushes the predicted speed limit for rotation. "I would say that...

Hyperbolic space is an unimaginable concept, unless you're a Latvian mathematician who's handy with needle and yarn. ___ On a Thursday night in Ithaca, New York, Daina Taimina, an ebullient blond mathematician at Cornell University, sits at her kitchen table with her husband, David Henderson, a Cornell professor of geometry. In front of her sits a big Chinese bowl filled with crinkled forms made of gray, blue, red, and purple yarn. Reaching into the bowl, Taimina pulls out a woozy multicolored surface, the likes of which would have delighted Dr. Seuss. "This is an octagon with a 45 degree angle...

When played together, they compose the symphony of the universe. Or at least, that's the theory. There's a problem, though. The strings have too much range. So much, in fact, that for string theory to agree with the established laws of physics and mathematics, there must be not three but at least ten dimensions (including time) that are curled up and tucked away. And because each of these multidimensional landscapes requires a different string tuning, there are potentially billions and billions of different versions of string theory relating to billions and billions of different universes. Then there's the problem of...

In 1676, Isaac Newton explained his accomplishments through a simple metaphor. "If I have seen farther it is by standing on the shoulders of giants," he wrote. The image wasn't original to him, but in using it Newton reinforced a way of thinking about scientific progress that remains popular: We learn about the world though the vision of a few colossal figures... "The main difference today is there are so many people working on these deep problems," the physicist Brian Greene said recently. In one 15-page span of his best-selling book "The Elegant Universe" (1999), Greene mentions 24 scientists whose...

The essential claim of string theory is that what we perceive as electrons, photons and other sub-atomic particles are actually tiny one-dimensional snippets of energy vibrating furiously in 11 dimensions. The theory seemed, at first, to offer a promising path forward toward the goal of seamlessly melding relativity and quantum mechanics because it overcame mathematical problems that had dogged earlier efforts at reconciliation. Sadly, reality has turned out to be at odds with the dreams of string theorists. For starters, there seems to be no possible way to test string theory experimentally... More ominously, out of the deep mathematical recesses...

Dark energy - the mysterious force that is speeding up the expansion of the Universe - has been a part of space for at least nine billion years. That is the conclusion of astronomers who presented results from a three-year study using the Hubble Space Telescope. The finding may rule out some competing theories that predict the strength of dark energy changes over time. Dark energy makes up about 70% of the Universe; the rest is dark matter (25%) and normal matter (5%). "It appears this dark energy was already boosting the expansion of the Universe as much as...

Now a group of astronomers using the Hubble Space Telescope have discovered that billions of years before this mysterious antigravity overcame cosmic gravity and sent the galaxies scooting apart like muscle cars departing a tollbooth, it was already present in space, affecting the evolution of the cosmos... The new results, Dr. Riess and others said, provide new clues and place new limits on the nature of dark energy, a mystery that has thrown physics and cosmology into turmoil over the last decade... The data suggest that in fact dark energy has changed little, if at all, over the course of...

Why is it that string theory has become such a favoured paradigm? Have theoretical physicists deluded themselves? Have they been pressured by social forces to blind themselves to other possible theories? Is there a behind-the-scenes string-theory conspiracy that is propping up a pseudoscientific house of cards? ...An essential criterion is whether there is experimental evidence to support the theory. We have a description, called the Standard Model of particle physics, which agrees with observations exceedingly well, with a few small exceptions. A reactionary could ask, since the present model works so well, why bother to look for something new? From...