Showing posts with label Jacob Bekenstein. Show all posts
Showing posts with label Jacob Bekenstein. Show all posts

Friday, October 04, 2013

A Deeper Search for Building Blocks of Nature

National High Magnetic Field Laboratory
The strange properties of superconducting materials called “cuprates” (bismuth strontium calcium copper oxide is shown here), which cannot be described by known quantum mechanical methods, may correspond to properties of black holes in higher dimensions.
According to modern quantum theory, energy fields permeate the universe, and flurries of energy in these fields, called “particles” when they are pointlike and “waves” when they are diffuse, serve as the building blocks of matter and forces. But new findings suggest this wave-particle picture offers only a superficial view of nature’s constituents. See:

Signs of a Stranger, Deeper Side to Nature’s Building Blocks 
By: Natalie Wolchover, Quanta Magazine, July 1, 2013

Tuesday, May 15, 2012

Illusions of Grandeur?

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]


This is just a recoup of what had been transpiring since 2005. We have a pretty good picture of the ways such distinctions are held for perspective so that we may look inside the black hole? The labels of this blog entry help with this refreshing.

See Also:

Monday, September 05, 2011

A Holograpical Universe

Plato likened our view of the world to that of an ancient forebear watching shadows meander across a dimly lit cave wall. He imagined our perceptions to be but a faint inkling of a far richer reality that flickers beyond reach. Two millennia later, Plato’s cave may be more than a metaphor. To turn his suggestion on its head, reality—not its mere shadow—may take place on a distant boundary surface, while everything we witness in the three common spatial dimensions is a projection of that faraway unfolding. Reality, that is, may be akin to a hologram. Or, really, a holographic movie.

The journey to this peculiar possibility combines developments deep and far-flung—insights from general relativity; from research on black holes; from thermodynamics, quantum mechanics, and, most recently, string theory. The thread linking these diverse areas is the nature of information in a quantum universe.
Physicists Jacob Bekenstein and Stephen Hawking established that, for a black hole, the information storage capacity is determined not by the volume of its interior but by the area of its surface. But when the math says that a black hole’s store of information is measured by its surface area, does that merely reflect a numerical accounting, or does it mean that the black hole’s surface is where the information is actually stored? It’s a deep issue and has been pursued for decades by some of the most renowned physicists. The answer depends on whether you view the black hole from the outside or from the inside—and from the outside, there’s good reason to believe that information is indeed stored at the event horizon. This doesn’t merely highlight a peculiar feature of black holes. Black holes don’t just tell us about how black holes store information. 
Black holes inform us about information storage 
in any context. See:Our Universe May Be a Giant Hologram

See Also: Physics and Philosophie Pay attention too, #8. (And Stefan submits: What is the ontological status of AdS/CFT?)[also pay attention to comments relating to #8]

Wednesday, June 15, 2011

A Conformal Field Theory Approach?

Using the anti–de Sitter/conformal field theory correspondence to relate fermionic quantum critical fields to a gravitational problem, we computed the spectral functions of fermions in the field theory. By increasing the fermion density away from the relativistic quantum critical point, a state emerges with all the features of the Fermi liquid. See:String Theory, Quantum Phase Transitions, and the Emergent Fermi Liquid





Spacetime in String Theory
Dr. Gary Horowitz, UCSB
.

Conformal Field Theory

A conformal field theory is a quantum field theory (or statistical mechanics model at the critical point) that is invariant under the conformal group. Conformal field theory is most often studied in two dimensions where there is a large group of local conformal transformations coming from holomorphic functions.

If your not sure what I mean,  have a look at what is happening on the surface of the sphere, as a means from which  a 2D description,  is describing the black hole in a 5d space. Have you seen this image before?

String theorists describe the physics of black holes in five-dimensional spacetime. They found that these five-dimensional objects provide a good approximation of the quark-gluon plasma in one fewer dimension, a relationship similar to the one between a three-dimensional object and its two-dimensional shadow. Image: SLAC National Accelerator Laboratory
Recreating the conditions present just after the Big Bang has given experimentalists a glimpse into how the universe formed. Now, scientists have begun to see striking similarities between the properties of the early universe and a theory that aims to unite gravity with quantum mechanics, a long-standing goal for physicists.
“Combining calculations from experiments and theories could help us capture some universal characteristic of nature,” said MIT theoretical physicist Krishna Rajagopal, who discussed these possibilities at the recent Quark Matter conference in Annecy, France.

One millionth of a second after the Big Bang, the universe was a hot, dense sea of freely roaming particles called quarks and gluons. As the universe rapidly cooled, the particles joined together to form protons and neutrons, and the unique state of matter known as quark-gluon plasma disappeared.See: String theory may hold answers about quark-gluon plasma
***
Bekenstein Bound 


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
                                                                                ***


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 restrictied 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

*** 



Juan Maldacena:
The strings move in a five-dimensional curved space-time with a boundary. The boundary corresponds to the usual four dimensions, and the fifth dimension describes the motion away from this boundary into the interior of the curved space-time. In this five-dimensional space-time, there is a strong gravitational field pulling objects away from the boundary, and as a result time flows more slowly far away from the boundary than close to it. This also implies that an object that has a fixed proper size in the interior can appear to have a different size when viewed from the boundary (Fig. 1). Strings existing in the five-dimensional space-time can even look point-like when they are close to the boundary. Polchinski and Strassler1 show that when an energetic four-dimensional particle (such as an electron) is scattered from these strings (describing protons), the main contribution comes from a string that is close to the boundary and it is therefore seen as a point-like object. So a string-like interpretation of a proton is not at odds with the observation that there are point-like objects inside it.

***

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 correspondance between states in our four dimensional world and states in higher dimensions. From a positivist viewpoint, one cannot distinquish which discription is more fundamental.

Pg 198, The Universe in Nutshell, by Stephen Hawking

***

In 1919, Kaluza sent Albert Einstein a preprint --- later published in 1921 --- that considered the extension of general relativity to five dimensions. He assumed that the 5-dimensional field equations were simply the higher-dimensional version of the vacuum Einstein equation, and that all the metric components were independent of the fifth coordinate. The later assumption came to be known as the cylinder condition. This resulted in something remarkable: the fifteen higher-dimension field equations naturally broke into a set of ten formulae governing a tensor field representing gravity, four describing a vector field representing electromagnetism, and one wave equation for a scalar field. Furthermore, if the scalar field was constant, the vector field equations were just Maxwell's equations in vacuo, and the tensor field equations were the 4-dimensional Einstein field equations sourced by an EM field. In one fell swoop, Kaluza had written down a single covariant field theory in five dimensions that yielded the four dimensional theories of general relativity and electromagnetism. Naturally, Einstein was very interested in this preprint .(sorry link now dead)

Wednesday, March 26, 2008

Blackhole Information Paradox

What good is a universe without somebody around to look at it?
Robert Dicke


John Archibald Wheeler (born July 9, 1911) is an eminent American theoretical physicist. One of the later collaborators of Albert Einstein, he tried to achieve Einstein's vision of a unified field theory. He is also known as the coiner of the popular name of the well known space phenomenon, the black hole.

There is always somebody who is the teacher and from them, their is a progeny. It would not be right not to mention John Archibald Wheeler. Or not to mention some of his students.

Notable students
Demetrios Christodoulou
Richard Feynman
Jacob Bekenstein
Robert Geroch
Bei-Lok Hu
John R. Klauder
Charles Misner
Milton Plesset
Kip Thorne
Arthur Wightman
Hugh Everett
Bill Unruh



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.


It is important to me to understand some of the history of the Blackhole, and the students who went on to develop the very ideas around them. To see how they interconnect at one time or another, to provide for the very insights from such gatherings.




Stephen Hawking’s says:

“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.”
( Chapter Six-The Large, the Small and the Human Mind-Roger Penrose-Cambridge University Press-1997)
See: Phil Warnell's comment.

Black hole information paradox


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


Drawing Credit: XMM-Newton, ESA, NASA-Image sourced from: Pictured above is an artist's illustration of a black hole surrounded by an accretion disk.

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.




Before the Big Bang

Professor Sir Roger Penrose, OM, FRS (born 8 August 1931) Before the Big Bang

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.


See:If an Electron Can Be in Two Places at Once, Why Can't You-by Tim Folger, Photograph by David Berry, Illustrations by Don Foley?

"In Penrose’s interpretation, gravity holds our reality together. In each potential state, the block generates a separate gravitational field.....," rings with a certain importance when one talks about what happens with the very nature of the blackhole. What happens to that information.

Phil Warnell:However, if the second is taken as truth and all is remembering, then what can the force of gravity do to a memory that is not in any, yet of all?

I tried to implement a method by which one could "gauge the significance of the emotive experience" as it may pertain to that "primitive part" of our nature. That we could see "remembering" had been assigned a "quantum reductionist state" within the confines of that methodology?

See:Quantum State reduction as a real phenomenon by Roger Penrose (Oxford)2 Sep 1999

"The block," while holding different gravitational defined consciousness states, had to settle to a strong emotive consolidating force from that experience. You repeatedly relive the experience, while current information saids that the memory can change. See Ledoux.

See:

Dennis William Sciama
Tipping LightCones and Escape Velocity of the Photon
What is Happening at the Singularity?
Science and the Mind: Sir Roger Penrose
Big Bang:One Man's Change of Heart

Friday, March 07, 2008

What is Happening at the Singularity?

WEll, some of the commentors like myself are not worth counting?:)Thanks for keeping it interesting Clifford of Asymptotia. I hope you won't mind the following quotes for consideration.( it was considered spam) so I reprint it here.

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




Is there not some way presented by Susskind which can help one approach understanding of what is going on in the blackhole by incorporating his "thought experiment" in relation to the entanglement process?

So of course questions about "the horizon" are interesting.



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


So we have these diagrams and thought processes developed from individuals like Jacob D. Bekenstein to help us visualize what is taking place. Gives us key indicators of the valuation needed, in order to determine what maths are going to be used? In this case the subject of Conformal Field Theory makes itself known, for the thought process?

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


So we are given the label in which to speak about the holographic notions of what is being talked about in the case of the blackhole's horizon.


Campbell's Soup Can by Andy Warhol Exhibited in New York (USA), Leo Castelli Gallery


Spacetime in String Theory-Dr. Gary Horowitz, UCSB-Apr 20, 2005

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,


See: Stringy Geometry

Saturday, December 15, 2007

The Gravity People of our History

What good is a universe without somebody around to look at it?
Robert Dicke


John Archibald Wheeler (born July 9, 1911) is an eminent American theoretical physicist. One of the later collaborators of Albert Einstein, he tried to achieve Einstein's vision of a unified field theory. He is also known as the coiner of the popular name of the well known space phenomenon, the black hole.

There is always somebody who is the teacher and from them, their is a progeny. It would not be right not to mention John Archibald Wheeler. Or not to mention some of his students.

Notable students
Demetrios Christodoulou
Richard Feynman
Jacob Bekenstein
Robert Geroch
Bei-Lok Hu
John R. Klauder
Charles Misner
Milton Plesset
Kip Thorne
Arthur Wightman
Hugh Everett
Bill Unruh



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.



While people are drawn to the "micro-perspective" it is in face of this, that I fall behind on the "many blog postings" and "current events." I try to maintain a perspective about GR and the development of this process through understanding the history.

I also pay attention to those who use "relevant phrases" to let me know they are continuing to read this blog site. Even in face of the layman status I have. I pay attention also to the information they are imparting and try to incorporate new information from their blogs, within the scope of my understanding, to make sure that I am not misleading others. Thinking this artist( in the conceptual developmental phases) has some wish to be firm in the places science is currently residing.



Most people think of space as nothingness, the blank void between planets, stars, and galaxies. Kip Thorne, the Feynman Professor of Theoretical Physics at Caltech, has spent his life demonstrating otherwise. Space, from his perspective, is the oft-rumpled fabric of the universe. It bends, stretches, and squeezes as objects move through it and can even fold in on itself when faced with the extreme entities known as black holes. He calls this view the “warped side of the universe.”

Strictly speaking, Thorne does not focus on space at all. He thinks instead of space-time, the blending of three spatial dimensions and the dimension of time described by Einstein’s general relativity. Gravity distorts both aspects of space-time, and any dynamic event—the gentle spinning of a planet or the violent colliding of two black holes—sends out ripples of gravitational waves. Measuring the direction and force of these waves could teach us much about their origin, possibly even allowing us to study the explosive beginning of the universe itself. To that end, Thorne has spearheaded the construction of LIGO [Laser Interferometer Gravitational Wave Observatory], a $365 million gravitational-wave detector located at two sites: Louisiana and Washington State. LIGO’s instruments are designed to detect passing gravitational waves by measuring minuscule expansions and contractions of space-time—warps as little as one-thousandth the diameter of a proton.
Despite the seriousness of his ideas, Thorne is also famous for placing playful bets with his longtime friend Stephen Hawking on questions about the nature of their favorite subject, black holes. Thorne spoke with DISCOVER about his lifetime pursuit of science, which sometimes borders on sci-fi, and offers a preview of an upcoming collaboration with director Steven Spielberg that will bring aspects of his warped world to the big screen.


So some are quick to call Kip Thorne and his ilk the fantasy and science fiction editors of our times, when progressing to the new movies they will collaborate on. So maybe rightly so here. But to bunch them into the likes of string theorists, to somehow further their goal on their own "mission to enlighten," how Peter Woit do you think so?

Peter Woit said,
Thorne expects that nothing in the film will violate fundamental physical law. He also seems rather involved in fantasy as well as science fiction, believing that the LHC has a good shot at producing mini-black holes, and that String theory is now beginning to make concrete, observational predictions which will be tested.


The very basis of research and development "has a long arm here" developed from the likes of the "small interferometer that we know "works," as a qualitative measure of the fabric of our universe, as the Ligo Operation.

Don't be so smug to think that what is fantasy in the world of good science people was somehow related to "what you may think" and does not have any validity in the mathematical realm of the string theoretical development.

It all happens in stages as we all know to well?