Paradox Solved? How Information Can Escape from a Black Hole
Every black hole conceals a secret — the quantum remains of the star from which it formed, say a group of scientists, who also predict that these stars can later emerge once the black hole evaporates.
The researchers call these objects “Planck stars” and believe that they could solve a very important question in modern physics: the information paradox, or the question of what happens to information contained in matter that falls into a black hole.
The idea could also finally reconcile quantum mechanics and Albert Einstein’s general theory of relativity that describes gravity, thus showing how a theory of quantum gravity might solve longstanding puzzles in the world of physics.
Life Cycle of Stars
In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA’s Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.
Image Credit: NASA, Wolfgang Brandner JPL-IPAC, Eva K. Grebel
Rhea, the second largest moon of Saturn, is a dirty snowball of rock and ice. The only moon with an oxygen atmosphere, thin though it may be, Rhea is one of the most heavily cratered satellites in the solar system.
A very faint oxygen atmosphere exists around Rhea, the first direct evidence of an oxygen atmosphere on a body other than Earth. The atmosphere is thin, with oxygen measuring about 5 trillion times less dense than that found on Earth. Oxygen could be released as the surface is irradiated by ions from Saturn’s magnetosphere. The source of the carbon dioxide is less clear, but could be the result of similar irradiation, or from dry ice much like comets.
On March 6, 2008, NASA announced that Rhea may have a tenuous ring system. This would mark the first discovery of rings about a moon. The rings’ existence was inferred by observed changes in the flow of electrons trapped by Saturn’s magnetic field as Cassini passed by Rhea. Dust and debris could extend out to Rhea’s Hill sphere, but were thought to be denser nearer the moon, with three narrow rings of higher density. The case for a ring was strengthened by the subsequent finding of the presence of a set of small ultraviolet-bright spots distributed along Rhea’s equator (interpreted as the impact points of deorbiting ring material).However, when Cassini made targeted observations of the putative ring plane from several angles, no evidence of ring material was found, but there’s still something around Rhea that is causing a strange, symmetrical structure in the charged-particle environment around Saturn’s second-largest moon.
Image credit: NASA/JPL-Caltech/SSI,Gordan Ugarkovic