kisma Johnson's blog: "Peering into the heart of a black hole"

Giant-sized telescopes such as Hubble, Spitzer and Chandra offer unprecedented views of the cosmos, but astronomers are eager to put more powerful tools into orbit around the Earth. Without the extra help, said Rachel Somerville, an astronomer at the Max Planck Institute for Astronomy in Germany, it may be impossible to resolve some of the universe's greatest mysteries. "We need better observations to make our models better," Somerville said, noting her search to understand galaxy formation and mysterious quasars. "... If you just put theorists in a room for the next 15 years with the biggest supercomputer you can find, it will never happen." NASA expects the James Webb Space Telescope (JWST) to launch in 2013, and many scientists are already pondering their future observations of tiny extrasolar planets, elusive black holes and distant galactic arms. Somerville and other astronomers laid bare their sky-watching hopes—including telescopes beyond JWST—at the recent Astrophysics 2020 conference, sponsored by Johns Hopkins University and held at the Space Telescope Science Institute in Baltimore. JWST will boast a segmented mirror nearly 21 feet (6.4 meters) in diameter, which has seven times the light-collecting area of Hubble. Somerville thinks the sensitive infrared observatory will be crucial for understanding galaxy formation. "If you don't have a high enough resolution, galaxies you're trying to observe are going look like fuzzy blobs," Somerville said. "Seeing the star-filled arms of galaxies in detail, for example, can tell us how some galaxies evolved." And the higher the resolution, the further a telescope can see back in time, as light can take millions or billions of years to reach Earth. While Somerville said NASA's next "great observatory" will deliver unprecedented views of galactic arms, she thinks the telescope could use some help to speed along other cosmic discoveries.

Astronomers may have unwittingly hastened the end of the Universe by simply looking at it, according to a theory reported in next Saturday's New Scientist. The novel idea is being aired by two US physicists, who attack the notion that the Universe, believed to have been created in the "Big Bang" some 13.7 billion years ago, will go on, well, forever. In fact, the poor old cosmos is in a rather delicate state, they say. Until recently, a common idea was that the energy unleashed in the Big Bang happened when a "false vacuum" - a bubble of high energy with repulsive gravity - broke down into a safe, zero-energy "ordinary" vacuum. But recent evidence has emerged that places a cosmic question-mark over this cosy thought. For one thing, cosmologists have discovered that the Universe is still expanding. And, they believe, a strange, yet-to-be-detected form of energy called dark energy pervades the Universe, which would explain why the sum of all the visible sources of energy fall way short of what should be out there. Dark energy, goes the thinking, is a result of the Big Bang and is accelerating the Universe's expansion. If so, the Universe is not in a nice, stable zero-vacuum state but simply another "false vacuum" state that may abruptly decay again - and with cataclysmic consequences. The energy shift from the decay would destroy everything in the Universe, "wiping the slate clean," says Lawrence Krauss of Case Western Reserve University in Cleveland, Ohio. The good news is: the longer the Universe survives, the better the chance that it will mature into a stable state. We are just beyond the crucial switching point, believes Krauss. The bad news is: the quantum effect, a truly weird aspect of physics that says whenever we observe or measure something, we reset its clock. Krauss and colleague James Dent point to measurements of light from supernovae in 1998 that provided the first evidence of dark energy. These measurements may have reset the decay clock of the "false vacuum" back to zero, back before the switching point and to a time when the risk of catastrophic decay was greater than now, say Dent and Krauss.

According to a group of mathematicians, it may be possible to create devices with internal tunnels that are invisible to detection by electromagnetic waves—wormholes, in a sense. The group discusses the idea in a paper published in the October 29 online edition of Physical Review Letters. The scientists say that by custom designing the values of two parameters that describe electromagnetic (EM) materials, the electrical permittivity and magnetic permeability, around and inside a cylinder, a novel optical device could be produced. Essentially, most of the device would be invisible to detection by external EM radiation of a certain frequency, with only the ends of the cylinder being visible and accessible to the EM waves. “The chosen values for the permittivity and permeability would cause the coating to manipulate EM waves in a way that is not seen in nature,” explained University of Rochester mathematician Allan Greenleaf, one of the paper's authors, to PhysOrg.com. Permittivity is a measure of a material's readiness to become electrically polarized in response to an applied electric field (how well it “permits” the field). Permeability describes how magnetized a material becomes when a magnetic field is applied. Modern EM materials known as metamaterials allow theoretical designs, such as a wormhole, to be physically constructed, at least in principle. Greenleaf and his colleagues, Yaroslav Kurylev of University College in London, Matti Lassas of the Helsinki University of Technology, and Gunther Uhlmann of the University of Washington, use the word “wormhole” in more of a mathematical sense than physical. That is, the devices would act as wormholes from the viewpoint of Maxwell's equations, the four fundamental equations that describe the relationship between electric fields, magnetic fields, electric charge, and electric current. For any other frequencies than those for which the permittivity and permeability were designed, the tunnel region would look roughly like a solid cylinder.

Quantum mechanics might be capable of stripping bare a black hole to reveal the mysterious and unseeable 'singularity' that exists at its heart, say George Matsas and André da Silva of the São Paulo State University in Brazil. It has long been suspected that these singularities "where the known laws of physics break down" are always decorously veiled behind the 'event horizon', a boundary beyond which light cannot escape from the fearsome gravitational pull of a black hole. Theoretically, nothing within an event horizon can ever be perceived or investigated by an outside observer, because no light can escape. So the singularities remain insulated from the rest of the Universe. This amounts to what in 1969 physicist Roger Penrose called 'cosmic censorship', whereby the laws of physics conspire to save us from having to gaze on the unthinkable. According to Einstein's general theory of relativity, in the middle of a black hole, its mass collapses in on itself to form an infinitely small, infinitely dense point, where space-time itself is punctured. Even causality " the relation of a cause and its effect " breaks down, which seems to defy not only physics but logic. "Penrose's motivation seemed to be to preserve the decorum of physics," Matsas says. But physicists have wondered whether event horizons are ever stripped away, leaving these absurdist singularities naked. One possibility, for example, is that the event horizon might vanish if a black hole spins very fast. Light and matter might then be flung out by centrifugal force. "It is widely believed that quantum gravity will unveil the structure of the singularities."In September, physicists Arlie Petters of Duke University in Durham, North Carolina, and Marcus Werner of the University of Cambridge, UK, proposed that singularities stripped naked by fast rotation should be detectable by astronomers because they act as very strong 'gravitational lenses', bending the light coming from stars behind them by their distortion of space-time.