![]() Polchinski's talk to the New York University physics department drew a standing-room-only crowd, not a single person snuck out early, and he was still fending questions an hour after it ended.Īlmost as much has been written about Hawking's original paradox (including by me) as about the fiscal cliff, so I'll jump straight to the new version. Polchinski blogged about it a few months ago, and another theorist who helped to usher in the idea, John Preskill, did so last week. I first heard about their brainstorm while visiting the Kavli Institute for Theoretical Physics in Santa Barbara this spring, and the team-Polchinski and fellow Santa Barbarans Don Marolf, Ahmed Almheiri, and James Sully- wrote it up over the summer. Polchinski and his colleagues have shown that the predicament is even worse than physicists used to think. The worst trouble is the black hole information paradox that Stephen Hawking loosed upon the world in 1976. ![]() Black holes are where the known laws of physics come into their most direct conflict. They are just insanely curious about what would happen. It's not because they have some peculiar death wish or because science funding prospects are so dark these days. ![]() He can find meaningful information from these data.In chatting with colleagues after a talk this week, Joe Polchinski said he'd love to fall into a black hole. Thus, the physicist can compare and interpret the data intelligently. The numbers in the reports are translated into data in Schwarzschild coordinates, which provide a systematic means of evaluating and describing the events globally. The bookkeeper gathers and combines the reports from various places. Observers local to the events are enlisted to make measurements and send the results to him. Instead, he is far away from the black hole and the events. He does not directly make measurements of events that occur in different places. The metric is expressed in the +−−− sign convention.įree falling worldlines in classic Schwarzschild-Droste coordinatesĪ Schwarzschild observer is a far observer or a bookkeeper. The gravitational constant has a value of 1. The speed of light in flat spacetime has a value of 1. The derivation of GP coordinates requires defining the following coordinate systems and understanding how data measured for events in one coordinate system is interpreted in another coordinate system.Ĭonvention: The units for the variables are all geometrized. That these solutions were simply coordinate transformations of the usual Schwarzschild solution, although Einstein immediately believed that to be true. It was not explicitly shown until 1933 in Lemaître's paper The solution was proposed independently by Paul Painlevé in 1921 and Allvar Gullstrand in 1922. ![]() The outgoing ones are simply the time reverse of ingoing coordinates (the time is the proper time along outgoing particles that reach infinity with zero velocity). There is no coordinate singularity at the Schwarzschild radius (event horizon). ![]() The ingoing coordinates are such that the time coordinate follows the proper time of a free-falling observer who starts from far away at zero velocity, and the spatial slices are flat. Gullstrand–Painlevé coordinates are a particular set of coordinates for the Schwarzschild metric – a solution to the Einstein field equations which describes a black hole. Coordinates suitable for following a free-falling observer of a Schwarzchild black hole ![]()
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