Information Preservation and Weather Forecasting for Black Holes by Stephen Hawking
It has been suggested (arXiv) that the resolution of the information paradox for evaporating black holes is that the holes are surrounded by firewalls, bolts of outgoing radiation that would destroy any infalling observer. Such firewalls would break the CPT invariance of quantum gravity and seem to be ruled out on other grounds. A different resolution of the paradox is proposed, namely that gravitational collapse produces apparent horizons but no event horizons behind which information is lost. This proposal is supported by ADS-CFT and is the only resolution of the paradox compatible with CPT. The collapse to form a black hole will in general be chaotic and the dual CFT on the boundary of ADS will be turbulent. Thus, like weather forecasting on Earth, information will effectively be lost, although there would be no loss of unitarity.
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The idea that there are no points from which you cannot escape a black hole is in some ways an even more radical and problematic suggestion than the existence of firewalls, but the fact that we’re still discussing such questions 40 years after Hawking’s first papers on black holes and information is testament to their enormous significance.
Image source: commons
Quantum quest by Andy Potts
Structure of a proton via @smoot_
Hydrogen Atom Orbitals
First few hydrogen atom orbitals; cross section showing color-coded probability density for different n=1,2,3 and l=”s”,”p”,”d”; note: m=0
The picture shows the first few hydrogen atom orbitals (energy eigenfunctions). These are cross-sections of the probability density that are color-coded (black=zero density, white=highest density). The angular momentum quantum number l is denoted in each column, using the usual spectroscopic letter code (“s” means l=0; “p”: l=1; “d”: l=2). The main quantum number n (=1,2,3,…) is marked to the right of each row. For all pictures the magnetic quantum number m has been set to 0, and the cross-sectional plane is the x-z plane (z is the vertical axis). The probability density in three-dimensional space is obtained by rotating the one shown here around the z-axis.
Note the striking similarity of this picture to the diagrams of the normal modes of displacement of a soap film membrane oscillating on a disk bound by a wire frame. See, e.g., Vibrations and Waves, A.P. French, M.I.T. Introductory Physics Series, 1971, ISBN 0393099369, page 186, Fig. 6-13. See also Normal vibration modes of a circular membrane.
A class of fluorescent organic molecule has been designed that enables highly efficient light-emitting diodes to be made. The devices may turn out to be competitors to their conventional analogues.
Image caption: a, Energy diagram of a conventional organic molecule. b, Molecular structures of CDCBs. Me, methyl; Ph, phenyl.
Image source: Uoyama H., Goushi K., Shizu K., Nomura H. & Adachi C. (2012). Highly efficient organic light-emitting diodes from delayed fluorescence, Nature, 492 (7428) 234-238. DOI: 10.1038/nature11687
Fully fledged quantum computers are still a long way off. But devices that can simulate quantum systems are proving uniquely useful.
Phase diagram of QCD matter in the temperature–baryon density plane. Baryons are hadrons containing three valence quarks; the most common are protons and neutrons, shown at the lower left. Colored spheres indicate individual quarks, which are not bound together in the quark-gluon plasma. RHIC (blue ovals) and LHC (green oval) explore matter with almost equal numbers of quarks and antiquarks. At lower beam energies, RHIC produces matter with a surplus of quarks, corresponding to high net baryon density. There may be a critical point (yellow circle) in the phase diagram, at the end of a line indicating a first-order phase transition.
Credit: Brookhaven National Laboratory
Researchers at JPL and Caltech have developed an instrument for exploring the cosmos and the quantum world.
This new type of amplifier boosts electrical signals and can be used for everything from studying stars, galaxies and black holes to exploring the quantum world and developing quantum computers. An amplifier is a device that increases the strength of a weak signal.
One of the key features of the new amplifier is that it incorporates superconductors—materials that allow an electric current to flow with zero resistance when lowered to certain temperatures. For their amplifier, the researchers are using titanium nitride and niobium titanium nitride, which have just the right properties to allow the pump signal to amplify the weak signal.
Although the amplifier has a host of potential applications, the reason the researchers built the device was to help them study the universe. The team built the instrument to boost microwave signals, but the new design can be used to build amplifiers that help astronomers observe in a wide range of wavelengths, from radio waves to X-rays.
Image Credit: NASA/JPL-Caltech
My mysterious Mr. Higgs, from The God Particle: If the Universe Is the Answer, What is the Question? by Leon Lederman