Malcom J. Perry "Black Hole Memory"
See Also: Backreaction: More about Hawking and Perry’s new proposal to solve the black hole information loss problem
What are black holes? What are they made of? What is string theory? Is everything we see just vibrations of strings? How are string theory and black holes related? What are the fundamental laws of Nature?
For decades, since the discovery of quantum mechanics and Einstein’s theory of relativity, scientists have been trying to combine the two perspectives of the world into one single unified theory. One of the results was string theory: where the strangeness of quantum reality and the weirdness of relativity theory come together and create something even more puzzling - a world with extra dimensions
String theory says that there is only one fundamental object in the universe: the string. Much like the strings in a guitar give rise to different sounds when you pluck them, the strings of string theory give rise to the different constituents of the observed reality when you make them vibrate at different energies. Is everything in the world made of strings? If so, what is a black hole? SEE: Black Holes, String Theory and the Fundamental Laws of Nature with Andrew Strominger
Volume 66, Issue 4, April 2013
Quantum mechanics teaches that black holes evaporate by radiating particles—a lesson indicating that at least one pillar of modern physics must fall. See: Black holes, quantum information, and the foundations of physics by Steven B. Giddings, in Physics Today, April 2013
Citation: Phys. Today 66, 4, 30 (2013); http://dx.doi.org/10.1063/PT.3.1946
Citation: Phys. Today 66, 4, 30 (2013); http://dx.doi.org/10.1063/PT.3.1946
|Black Holes Shine for NuSTAR Image Credit: NASA/JPL-Caltech|
NASA's black-hole-hunter spacecraft, the Nuclear Spectroscopic Telescope Array, or NuSTAR, has "bagged" its first 10 supermassive black holes. The mission, which has a mast the length of a school bus, is the first telescope capable of focusing the highest-energy X-ray light into detailed pictures. See: Catching Black Holes on the Fly
In February 2013 I was invited by the Institute of Physics to give a lecture in the famous lecture theatre of the Royal Institution of Great Britain as part of their Physics in Perspective series. I was to expect about 400 students and teachers from schools across the country. See: How to Find Black holes with Lasers
NuSTAR is opening a new window on the Universe by being the first satellite to focus high-energy X-rays into sharp images. NuSTAR’s high-energy X-rays eyes see with more than 100 times the sensitivity of previous missions that have operated in this part of the electromagnetic spectrum, and with 10 times better resolution. NuSTAR sheds light on some of the hottest, densest, and most energetic objects in the universe.Education & Outreach
The Foundational Questions Institute (FQXi) 2nd International Conference in Ponta Delgada, Azores. July 7-12, 2009. Topics include cosmology, astrophysics, gravity, quantum gravity, quantum theory, and high-energy physics. http://www.fqxi.org/
Meduso-Anthropic Principle is a speculative theory by Louis Crane (1994). The theory develops Cosmological natural selection by leading cosmologist, Lee Smolin and suggests the development of the universe is similar to the development of Corals and Jellyfish. The Medusa generations alternate with Polyp generations. Similarly it is suggested, the Universe develops Intelligent life and Intelligent life produces new Baby universes. Our universe may also exist as a Black hole in a Parallel universe. Extraterrestrial life there may have created that black hole.
Bringing the Heavens down to Earth
If mini black holes can be produced in high-energy particle interactions, they may first be observed in high-energy cosmic-ray neutrino interactions in the atmosphere. Jonathan Feng of the University of California at Irvine and MIT, and Alfred Shapere of the University of Kentucky have calculated that the Auger cosmic-ray observatory, which will combine a 6000 km2 extended air-shower array backed up by fluorescence detectors trained on the sky, could record tens to hundreds of showers from black holes before the LHC turns on in 2007......Thus, hypothetically, the energy required to produce black holes is well within the range of the LHC, making it a "black-hole factory". As Stephen Hawking has taught us, these mini black holes would be extremely hot little objects that would dissipate all their energy very rapidly by emitting radiation and particles before they wink out of existence. The properties of the Hawking radiation could tell us about the properties of the extra spatial dimensions, although there are still uncertainties in the theory at this stage. See: here
We have been assured black hole production can be quite safe so we can deal with the idea that such production quickly dissipates on the level with which we would and can make them?:) So the level at which such an idea is presented would of course be as suggested as to say that this universe in all it's ability is at the level with which we can make black-holes useful? Black holes of sufficient size.:) I find that really interesting, just because we are here.
Which leads to a prediction or an observation that after many, many generations the population of the universes should be fine-tuned to maximize the production of Black Holes. And that has further implications for things that we can actually try to measure and disprove experimentally. So that's, very briefly, the idea of cosmological natural selection.
You see, people are uncomfortable with this information loss. It’s the minority view.Pg 64, The Cyclic Universe: A Conversation with Roger Penrose
|(Courtesy: NASA E/PO, Sonoma State University, Aurore Simonnet)|
The birth of a black hole may be signalled by a characteristic cosmic flash, according to researchers in the US. It was previously thought that only the most massive of black holes would produce gamma-ray bursts – narrow beams of electromagnetic radiation that shoot out of the poles of the collapsing star – when they form. But other dying stars were thought to produce a black hole without any kind of flash – seemingly disappearing from the visible sky in an event known as an "unnova". The US researchers' work suggests that unnovae might also have their own characteristic flash, allowing astronomers to witness the birth of stellar- and intermediate-mass black holes. See:
Cosmic flashes could herald birth of black holes
The continuing difficulty of achieving a reliable explosion in simulations of core-collapse supernovae, especially for more massive stars, has led to speculation concerning the observable transients that might be produced if such a supernova fails. Even if a prompt outgoing shock fails to form in a collapsing presupernova star, one must still consider the hydrodynamic response of the star to the abrupt loss of mass via neutrinos as the core forms a protoneutron star. Following a suggestion by Nadezhin (1980), we calculate the hydrodynamical responses of typical supernova progenitor stars to the rapid loss of approximately 0.2 to 0.5 M_sun of gravitational mass from their centers. In a red supergiant star, a very weak supernova with total kinetic energy ~ 10^47 erg results. The binding energy of a large fraction of the hydrogen envelope before the explosion is of the same order and, depending upon assumptions regarding the neutrino loss rates, most of it is ejected. Ejection speeds are ~ 100 km/s and luminosities ~ 10^39 erg/s are maintained for about a year. A significant part of the energy comes from the recombination of hydrogen. The color of the explosion is extremely red and the events bear some similarity to "luminous red novae," but have much lower speeds. See: Very Low Energy Supernovae from Neutrino Mass Loss
NASA contracted with Orbital Sciences Corporation to launch NuSTAR (mass 772 pounds (350 kg)) on a Pegasus XL rocket for 21 March 2012. It had earlier been planned for 15 August 2011, 3 February 2012, 16 March 2012, and 14 March 2012. After a launch meeting on 15 March 2012, the launch was pushed further back to allow time to review flight software used by the launch vehicle's flight computer. The launch was conducted successfully at 16:00:37 UTC on 13 June 2012 about 117 nautical miles south of Kwajalein Atoll. The Pegasus rocket was dropped from the L-1011 'Stargazer' aircraft.
On 22 June 2012 it was confirmed that the 10 m mast was fully deployed.
We argue that the following three statements cannot all be true: (i) Hawking radiation is in a pure state, (ii) the information carried by the radiation is emitted from the region near the horizon, with low energy effective field theory valid beyond some microscopic distance from the horizon, and (iii) the infalling observer encounters nothing unusual at the horizon. Perhaps the most conservative resolution is that the infalling observer burns up at the horizon. Alternatives would seem to require novel dynamics that nevertheless cause notable violations of semiclassical physics at macroscopic distances from the horizon. Black Hole: Complementarity vs Firewall
|See:The elephant and the event horizon 26 October 2006 by Amanda Gefter at New Scientist.|
Various neutron interferometry experiments demonstrate the subtlety of the notions of duality and complementarity. By passing through the interferometer, the neutron appears to act as a wave. Yet upon passage, the neutron is subject to gravitation. As the neutron interferometer is rotated through Earth's gravitational field a phase change between the two arms of the interferometer can be observed, accompanied by a change in the constructive and destructive interference of the neutron waves on exit from the interferometer. Some interpretations claim that understanding the interference effect requires one to concede that a single neutron takes both paths through the interferometer at the same time; a single neutron would "be in two places at once", as it were. Since the two paths through a neutron interferometer can be as far as 5 cm to 15 cm apart, the effect is hardly microscopic. This is similar to traditional double-slit and mirror interferometer experiments where the slits (or mirrors) can be arbitrarily far apart. So, in interference and diffraction experiments, neutrons behave the same way as photons (or electrons) of corresponding wavelength. See: Complementarity (physics)
|Illusions of Gravity|
Three spatial dimensions are visible all around us--up/down, left/right, forward/backward. Add time to the mix, and the result is a four-dimensional blending of space and time known as spacetime. Thus, we live in a four-dimensional universe. Or do we?
Amazingly, some new theories of physics predict that one of the three dimensions of space could be a kind of an illusion--that in actuality all the particles and fields that make up reality are moving about in a two-dimensional realm like the Flatland of Edwin A. Abbott. Gravity, too, would be part of the illusion: a force that is not present in the two-dimensional world but that materializes along with the emergence of the illusory third dimension.
UC Berkeley's Raphael Bousso presents a friendly introduction to the ideas behind the holographic principle, which may be very important in the hunt for a theory of quantum gravity. Series: "Lawrence Berkeley National Laboratory Summer Lecture Series" [3/2006] [Science] [Show ID: 11140]
What good is a universe without somebody around to look at it?
COSMIC SEARCH: How did you come up with the name "black hole"?
John Archibald Wheeler:It was an act of desperation, to force people to believe in it. It was in 1968, at the time of the discussion of whether pulsars were related to neutron stars or to these completely collapsed objects. I wanted a way of emphasizing that these objects were real. Thus, the name "black hole".
The Russians used the term frozen star—their point of attention was how it looked from the outside, where the material moves much more slowly until it comes to a horizon.* (*Or critical distance. From inside this distance there is no escape.) But, from the point of view of someone who's on the material itself, falling in, there's nothing special about the horizon. He keeps on going in. There's nothing frozen about what happens to him. So, I felt that that aspect of it needed more emphasis.
“Roger Penrose and I worked together on the large scale structure of space and time, including singularities and black holes. We pretty much agree on the classical theory of theory of relativity but disagreements began to emerge when we got into quantum gravity. We now have different approaches to the world, physical and mental. Basically, he is a Platonist believing that’s there’s a unique world of ideas that describes a unique physical reality. I on the other hand, am a positivist who believes that physical theories are just mathematical models we construct, and it is meaningless to ask if they correspond to reality; just whether they predict observations.”See: Phil Warnell's comment.
( Chapter Six-The Large, the Small and the Human Mind-Roger Penrose-Cambridge University Press-1997)
Whereas Stephen Hawking and Kip Thorne firmly believe that information swallowed by a black hole is forever hidden from the outside universe, and can never be revealed even as the black hole evaporates and completely disappears,
And whereas John Preskill firmly believes that a mechanism for the information to be released by the evaporating black hole must and will be found in the correct theory of quantum gravity,
Therefore Preskill offers, and Hawking/Thorne accept, a wager that:
When an initial pure quantum state undergoes gravitational collapse to form a black hole, the final state at the end of black hole evaporation will always be a pure quantum state.
The loser(s) will reward the winner(s) with an encyclopedia of the winner's choice, from which information can be recovered at will.
Stephen W. Hawking, Kip S. Thorne, John P. Preskill
Pasadena, California, 6 February 1997
The black hole Information Paradox results from the combination of quantum mechanics and general relativity. It suggests that physical information could "disappear" in a black hole. It is a contentious subject since it violates a commonly assumed tenet of science—that information cannot be destroyed. If it is true, then cause and effect become unrelated, and nothing science knows, not even our memories, can be trusted.
Three Different Views of Quantum Weirdness
(and What It Means)
A: According to the orthodox view of quantum mechanics, called the Copenhagen interpretation, a system (represented here by a child’s block) does not occupy a definite state or location until it is measured. Before then it is just a blur of overlapping possibilities.
B: The many worlds interpretation insists that the system occupies all its possible states but that every one of them exists in its own alternate universe. Each universe sees one state only, which is why we never observe the block in two states at once.
C: In Penrose’s interpretation, gravity holds our reality together. In each potential state, the block generates a separate gravitational field. Over time, the energy required to maintain these multiple fields causes the block to settle into one state only—the one that we observe.
fancier way of saying that is that in general, it's okay to model the space around us using the Euclidean metric. But the Euclidean model stops working when gravity becomes strong, as we'll see later. The Euclidean model for space
We are told that "mathematics is that study which knows nothing of observation..." I think no statement could have been more opposite to the undoubted facts of the case; that mathematical analysis is constantly invoking the aid of new principles, new ideas and new methods, not capable of being defined by any form of words, but springing direct from the inherent powers and activity of the human mind, and from continually renewed introspection of that inner world of thought of which the phenomena are as varied and require as close attention to discern as those of the outer physical world, ...that it is unceasingly calling forth the faculties of observation and comparison, that one of its principal weapons is induction, that it has frequent recourse to experimental trial and verification, and that it affords a boundless scope for the exercise of the highest efforts of imagination and invention. ...Were it not unbecoming to dilate on one's personal experience, I could tell a story of almost romantic interest about my own latest researches in a field where Geometry, Algebra, and the Theory of Numbers melt in a surprising manner into one another.
It was the beginning of what might be called (and in fact is called) Stringy Geometry. The point is that strings are not points, and specifically, their extended nature means that in addition to being able to see the usual geometrical properties of a space that the theory like General Relativity can see, the strings can see other, intrinsically stringy, data. There is a quantity in the theory that is called the Kalb-Ramond field (or just the “B-field”) that can be used to measure how much the string can winds on or wraps a piece of the geometry, in essence. The parameter a that measures the size of a piece of the space that collapses when the geometry becomes singular, is essentially joined by another parameter, b, that sort of measures how much the strings have wound or smeared themselves on that piece of the space. The upshot is that a and b naturally combine themselves into a complex parameter that naturally describes the resolution process, solving the puzzle that the Mathematicians faced.Beyond Einstein: Fixing Singularities in Spacetime
Quantum geometry differs in substantial ways from the classical geometry underlying general relativity. For instance, topology change (the "tearing" of space) is a sensible feature of quantum geometry even though, from a classical perspective, it involves singularities. As another example, two different classical spacetime geometries can give rise to identical physical implications, again at odds with conclusions based on classical general relativity. Brian Greene
Consider any physical system, made of anything at all- let us call it, The Thing. We require only that The Thing can be enclosed within a finite boundary, which we shall call the Screen(Figure39). We would like to know as much as possible about The Thing. But we cannot touch it directly-we are restricted to making measurements of it on The Screen. We may send any kind of radiation we like through The Screen, and record what ever changes result The Screen. The Bekenstein bound says that there is a general limit to how many yes/no questions we can answer about The Thing by making observations through The Screen that surrounds it. The number must be less then one quarter the area of The Screen, in Planck units. What if we ask more questions? The principle tells us that either of two things must happen. Either the area of the screen will increase, as a result of doing an experiment that ask questions beyond the limit; or the experiments we do that go beyond the limit will erase or invalidate, the answers to some of the previous questions. At no time can we know more about The thing than the limit, imposed by the area of the Screen. Page 171 and 172 0f, Three Roads to Quantum Gravity, by Lee Smolin
TWO UNIVERSES of different dimension and obeying disparate physical laws are rendered completely equivalent by the holographic principle. Theorists have demonstrated this principle mathematically for a specific type of five-dimensional spacetime ("anti–de Sitter") and its four-dimensional boundary. In effect, the 5-D universe is recorded like a hologram on the 4-D surface at its periphery. Superstring theory rules in the 5-D spacetime, but a so-called conformal field theory of point particles operates on the 4-D hologram. A black hole in the 5-D spacetime is equivalent to hot radiation on the hologram--for example, the hole and the radiation have the same entropy even though the physical origin of the entropy is completely different for each case. Although these two descriptions of the universe seem utterly unalike, no experiment could distinguish between them, even in principle. by Jacob D. Bekenstein
The old version of string theory, pre-1995, had these first two features. It includes quantum mechanics and gravity, but the kinds of things we could calculate were pretty limited. All of a sudden in 1995, we learned how to calculate things when the interactions are strong. Suddenly we understood a lot about the theory. And so figuring out how to compute the entropy of black holes became a really obvious challenge. I, for one, felt it was incumbent upon the theory to give us a solution to the problem of computing the entropy, or it wasn't the right theory. Of course we were all gratified that it did. Black Holes and Beyond: Harvard's Andrew Strominger on String Theory
Holography encodes the information in a region of space onto a surface one dimension lower. It sees to be the property of gravity, as is shown by the fact that the area of th event horizon measures the number of internal states of a blackhole, holography would be a one-to-one correspondence between states in our four dimensional world and states in higher dimensions. From a positivist viewpoint, one cannot distinguish which description is more fundamental.Pg 198, The Universe in Nutshell, by Stephen Hawking
This year marks the hundredth anniversary of Einstein's "miraculous year", 1905, when he formulated special relativity, and explained the origin of the black body spectrum and Brownian motion. In honor of this occasion, I will describe the modern view of spacetime. After reviewing the properties of spacetime in general relativity, I will provide an overview of the nature of spacetime emerging from string theory. This is radically different from relativity. At a perturbative level, the spacetime metric appears as ``coupling constants" in a two-dimensional quantum field theory. Nonperturbatively (with certain boundary conditions), spacetime is not fundamental but must be reconstructed from a holographic, dual theory. I will conclude with some recent ideas about the big bang arising from string theory.
The purpose of this note is to provide a possible answer to this question. Rather than the radical modification of quantum mechanics required for pure states to evolve into mixed states, we adopt a more mild modification. We propose that at the black hole singularity one needs to impose a unique final state boundary condition. More precisely, we have a unique final wavefunction for the interior of the black hole. Modifications of quantum mechanics where one imposes final state boundary conditions were considered in [6,7,8,9]. Here we are putting a final state boundary condition on part of the system, the interior of the black hole. This final boundary condition makes sure that no information is “absorbed” by the singularity.Gary T. Horowitz and Juan Maldacena,
3) It is claimed that cosmic rays can energy exceeding that of colliders, and they have not caused trouble, suggesting that colliders will not cause trouble either. However, the analogy is not precise. It assumes two things that may not be true. First, cosmic ray center of mass energy exceeding that of colliders has never been measured directly. Measurements that seem to show this are based on showers of secondary particles. Second, the product of a collision between a cosmic ray and an earth particle will always be moving at an appreciable fraction of the speed of light. If it has a small capture radius, it will always pass right through earth like a neutrino. The product of a collider collision can (sometimes) be moving at less than escape velocity from earth. If so, it will fall into earth where it will have forever to accrete other matter. Some calculations show rapid accretion.See: Risk Evaluation Forum
"I’m a Platonist — a follower of Plato — who believes that one didn’t invent these sorts of things, that one discovers them. In a sense, all these mathematical facts are right there waiting to be discovered."Donald (H. S. M.) Coxeter
Thus RHIC is in a certain sense a string theory testing machine, analyzing the formation and decay of dual black holes, and giving information about the black hole interior.
"String theory and other possibilities can distort the relative numbers of 'down' and 'up' neutrinos," said Jonathan Feng, associate professor in the Department of Physics and Astronomy at UC Irvine. "For example, extra dimensions may cause neutrinos to create microscopic black holes, which instantly evaporate and create spectacular showers of particles in the Earth's atmosphere and in the Antarctic ice cap. This increases the number of 'down' neutrinos detected. At the same time, the creation of black holes causes 'up' neutrinos to be caught in the Earth's crust, reducing the number of 'up' neutrinos. The relative 'up' and 'down' rates provide evidence for distortions in neutrino properties that are predicted by new theories."