Gauge Invariance

Happy 2012

2012-01-05T15:03:00.000-06:00

Happy new year to all readers of gauge invariance, this year I made a sign for you guys on Canadian snow,

and at the middle of the work I realized Invariance is too long for the size of my camera!

Hope you guys all have a productive year ahead!

- Mohammad

Spectroscopy of a black hole and its horizon entropy

2011-12-15T21:46:00.000-06:00

The idea of Isolated and Dynamical Horizon theory was first worked out by Heyward in 1994. He derived the complete definition of a marginally null surface that is trapped on a black hole horizon.

A few years later Ashtekar and his colleagues re-wrote the same theory in the language of Ashtekar- Sen variables. Before this development Rovelli has argued that a black hole entropy should be proportional with its horizon area. Lee Smolin linked loop quantum gravity to topological field theory and argued that a black hole should be described by a Chern Simon’s action.

Later on, Krasnov based on all the above mentioned ideas argued the derivation of a black hole entropy from the counting of puncture states. A ‘sequence’ of punctures on a horizon explains the wave function of the horizon. Being a sequence, the punctures are ordered and this make them distinguishable. However, there is no physical evidence why should one restricts the wave functions into a sequence and not a set of punctures in which there is no generic order, thus no distinguishability.

Given this in the quantum horizon theory, I noticed an internal degeneracy in the nature of area operator. Since the area eigenstates are insensitive to the completely tangential edges residing on the horizon, the edges describing a quantum surface carries a local distinguishability. The complete spectrum of area provides the Bekenstein-Hawking entropy, which using Olaf Dreyer’s conjecture it becomes consistent with the evaporation of minimal area cell with the corresponding area of the highly damping quanta.

This proposes a kinematical picture for defining a quantum horizon via spin foam models, however the dynamics of such a model has not yet initiated to be studied. . A new value was devoted to the Immirzi parameter. Considering the full spectrum of area and using the semi-classical conjecture that on a black hole the horizon area and the hole energy are proportional

I noticed a strong amplification in some selected frequencies radiated away from a black hole due to its horizon fluctuations. The full spectrum of a black hole radiation was extracted and the bright lines in the spectrum turn out to be unblended and narrow enough to become observable.

Josephson and Feynman in low temperature!

2011-12-13T12:25:00.000-06:00

We recently calculated noise power spectrum due to the presence of magnetic impurities in a Josephson junction explicitly, using Feynman diagrams. The long paper includes all details of integrations and calculations.

The results were presented is written in a way that serves as a good source to understand step by step the details of analysis of decoherence in mesoscopic superconducting systems that includes the Kondo effect through the Coulomb interactions Feynman diagrams in low temperature.

It was recently published in PRB in 19 pages.

Strom in Waterloo, Ontario

2011-09-04T00:29:00.000-05:00

I took this photo tonight from my balcony at Waterloo, where I was spectator of a rain storm. after many attempts I finally succeeded to take this shot from a lightning.

Irrelevant news from nature to loop quantum gravity

2011-08-28T13:36:00.000-05:00

Today I read this article from BBC that LHC results put supersymmetry theory in trouble.

The results do not rigorously demonstrate anything because Strings can exist without low-energy supersymmetry of Loops with supersymmetry. I do not understand why the community of loop quantum gravitists are this much happy about it?! Its certainly bad news for preliminary string theory, but how about loop quantum gravity? Loop Quantum Gravity does not rely on superstring theory but it can certainly handle that. Loop quantum gravity certainly is an alternating theory, but there are many other candidates to seek for using the foundations of quantum mechanics.

But certainly this result is without doubt so important to be argued for a long time between experts.

The paper of Kondo noise ...

2011-08-17T16:12:00.001-05:00

I and Frank worked on it, was accepted for publication in Physical Review B in the third week after submitted. This is a new score in short-time reviewing process perhaps because we paid it off from working on it for almost a year!

If you are working on the critical current noise in superconducting materials or in general you deal with superconducting qubits or SQUIDS, reading this paper is highly recommended.

You will find in it a good analytical approach to understand the complicated physics of a magnetic impurity inside a Josephson junction. With the consistency it provides with the Wilson type renormalization group method so far was used in the Kondo community, it equips us to study the critical current noise in a tunnel junction in the presence of a few free Oxygen molecules inside the tunnel junction oxide layer.

2011-07-12T10:49:00.001-05:00

Theory Canada 6 in the city of Corner Brook in Newfoundland, Canada was exciting and interesting. The nature of the city is unique and the core idea of the conference was intriguing: some of the Canadian theorists who due to the wide geography of this country cannot meet each other in a regular base gather in one place a few days before CAP conference and collaborate on exchanging ideas and thoughts.

Mohammad H. Ansari

Noise and microresonance of critical current in Josephson junction

2011-06-23T20:07:00.000-05:00

Along with Frank Wilhelm I enjoyed working on the noise study of a Josephson junction. The results appeared today at

arxiv.org/abs/1106.4794

We analyze the impact of trap states in the oxide layer of a superconducting tunnel junctions, on the fluctuation of the Josephson critical current, thus on coherence in superconducting qubits.

Two mechanisms are usually considered: the current blockage due to repulsion at the occupied trap states, and the noise from electrons hopping across a trap. We extend previous studies of noninteracting traps to the case where the traps have on-site electron repulsion inside one ballistic channel.

The repulsion not only allows the appropriate temperature dependence of 1/f noise, but also is a control to the coupling between the computational qubit and the spurious two-level systems inside the oxide dielectric.

We use second order perturbation theory which allows to obtain analytical formulae for the interacting bound states and spectral weights, limited to small and intermediate repulsions.

Remarkably, it still reproduces the main features of the model as identified from the Numerical Renormalization Group.

We present analytical formulations for the subgap bound state energies, the singlet-doublet phase boundary, and the spectral weights.

We show that interactions can reverse the supercurrent across the trap.

We finally work out the spectrum of junction resonators for qubits in the presence of on-site repulsive electrons and analyze its dependence on microscopic parameters that may be controlled by fabrication.

Meet other creatures

2011-03-29T08:49:00.003-05:00

Meet them in these scales of a meter:

10^-35: Quantum gravity domain. Planck's length.
10^-30:
10^-28:
10^-24: Neutrino
10^-21: Perons, the ingredients of quarks.
10^-18: Quarks. Electron cores.
10^-15: Protons.
10^-14: size of light nuclei.
10^-12: Gamma ray wavelength.
2*10^-12: electron Compton wavelength.
5*10^-12: X-ray wavelength.
2.5*10^-11: distance between two Hydrogen atom nuclei.
3.1*10^-11: distance between two Helium atom nuclei.
7.0*10^-11: distance between two Carbon atoms nuclei.
10^-10: distance between two Sulfure atom nuclei.
5*10^-10: width of Protein alpha Helix.
10^-9 (1 nano meter): Carbon nanotube.
2*10^-9: the smallest transistor gate of microprocessor.
3*10^-9: thickness of DNA.
10*10^-9: the width of cell membrane.
50*10-9: ultraviolate wavelength.
90*10^-9: HIV.
300*10^-9: Violate wavelength.
500*10^-9: largest virus.
600*10^-9: red light wavelength.
7*10^-6 (7 micrometer): red blood cell.
10*10^-6: infrared wavelength. Fog droplet. White blood cell.
50*10^-6: Pullen grain. Silt particle.
10^-4 (a tenth of milimeter): smallest things visible to naked eyes. Width of human hair.
2.5*10^-4: human egg.
3*10^-4: computer pixel.
5*10^-4: salt crystal grain. Thickness of human skin. Largest bacteria. Pencil lead.
7*10^-4: thickness of credit card.
10^-3: Ant. Sesame. etc.

The Fritz London Prize 2011

2011-03-03T18:04:00.001-06:00

is happy to hear the Fritz London Prize - highest award in low temperature physics after the nobel - is awarded to Hans Mooij in recognition for his experimental contributions to the understanding of nonequilibrium superconductivity, Josephson flux qubits, etc; at the same time to Gerd Schön in recognition of his theoretical contributions to the understanding of superconductivity in mesoscopic systems, including charge qubit; as well as to Humphrey Maris in recognition for his original theories and experimental discoveries in liquid helium, concerning phonons, Kapitza resistance, levitation, nucleation, electron bubbles and vortex imaging.

Conference Announcement NCMT 2011

2011-02-03T13:40:00.001-06:00

Another major event in the region of South Western Ontario for the community of nanostructure phyicisits:

International Conference on Frontier Topics in Nanostructures and Condensed Matter Theory
March 9-11, 2011at Western

URL: http://ncmt2011.uwo.ca/

The Kondo theory

2011-01-21T11:44:00.003-06:00

Additional unwanted qubits in a phase qubit due to the Kondo effect.
Simmonds et.al. Phys. Rev. Lett 2005

The Kondo effect is one of the interesting features of low temperatur physics where temperature is seen not to play as a smoother, instead it ruines the results taken from perturbation theory. Last Monday I presented a talk titled "the Kondo effect" in a Colloquium at the Institute for Quantum Computing IQC in Waterloo. It was a good opportunity to face with some interesting questions and comments...

In this talk I presented two exotic behavior of electron in low temperature, one in a quantum dot, and the second in the Josephson junction between two superconductors. In a quantum dots I explained the Kondo plateaus predicted in 1988 by Glazman and Raikh in JETP Lett. and they observed by van der Wiel et.al. Science 2000. In the second half, I explained how this effect can causes the presence of additional unwanted qubits interacting with the computational qubit. And finally our recent idea of how to suppress them to prevent errors on computations...

How much snow

2010-12-21T11:18:00.003-06:00

In the last three weeks there was about 2 meters of snow falling over London Ontario that caused the University to be closed for 4 days and the city buses not to operate for almost two days, due to the heavy load of snow on roads.

How much this city became heavier then?

With the area of almost 400 (km^2), so the volume of snow is 0.8 billion (m^3). The mass density of freshly fallen snow is around 10% of that of water, let let be it 100 (kg/m^3).

So the total mass of the snow is huge: 80 billions (kg).

This is equal to the mass of a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a small probability that it would strike the Earth in the year 2029!

How much power does this mass create?

If we consider the speed of rain droplets is a few meters per second, let us consider the speed of snow is at least 0.1(m/s), which produces the kinetic energy 1/200 (J/kg). This much snow fell on the city in 4 days therefore the rate of falling was 80 billions kilograms per four days, or 200,000 kg/s. The total power is 1000 Watts.

This snow generated 5% of the solar power radiated by sun over this city.

QISS 2010

2010-05-21T10:17:00.004-05:00

The wonderful QISS 2010 workshop was definitely a success for the organizer Institute. We saw the most modern form of qubits in semiconductors, superconductors, and the buckyball fullerenes. More information can be found in here, where the talks are supposed to become available online soon.

Quantum Amplification Effect on black holes

2010-05-21T09:20:00.003-05:00

Black holes radiate.

But recently it is shown they even more radiate!

In fact when their horizon fluctuates, they radiate on two or three frequencies that are heavily resonated, like a quantum amplifier.

These lines are at the range of frequency sensitivity that INTEGRAL may become able to find them. Perhaps we have observed them and do not recognize them as black hole QAE lines.

These lines could be foud in evenly or unevenly spaced fashion. in fact, Yakov Bekenstein and Viatcheslav Mukhanov predicted these lines (if are more than two) are exactly evenly spaced. With the support of theories that predict the spectrum of area scaling with the square-root of integers, we predicted they must be found in an unevenly-spaced fashion.

Details can be found in my recent Physical Reviews D paper...

This figure illustrates a quantum black hole horizon in the vicinity of a null boundary (the black sphere). In other words, you see a black hole as the interior black sphere underneath a discrete shell (the outer shell) that represents the hole's horizon area fluctuations.

The spectrum of a black hole radiation should be discrete, intense, and narrow line on top of weak the Hawking radiation.

The search for these lines in observational data is continued...

How to work with jpeg2ps software in Windows

2010-04-09T00:23:00.006-05:00

How to work with jpeg2ps software in Windows:

1- After installing GSView (read here for instruction), download jpeg2ps from here, (thanks to sourceforge.com!)

2- After downloading is finished, click on the file and install the software. Note at what folder it's going to be installed. Its default location is usually at "C:\Program Files\GnuWin32\"

3- (Copy and) paste a JPEG, which you want to convert it into eps, into "C:\Program Files\GnuWin32\bin".

4- On Windows "Start" click on "Run" and write in its empty box "cmd". A black DOS window will appear inside which a default directory is written, usually it is "C:/Program Files/Username>". Each time you write "cd.." in front of the ">" and enter this folder goes one root backwards, so by repeating this you can go back to "C:>". Write "cd Program Files\GnuWin32\bin" or "cd [The "bin" folder address where you installed jpeg2ps at]. Now you are where the software jpeg2ps is! (If you are DOS expert you know how to write shortcut.)

5- Write "jpeg2ps" and you'll see the option menu. It is time now to actually convert a sample picture. Assume the file "sample.jpeg" (which is located at C:\Program Files\GnuWin32\bin) should be converted to EPS.

6- Write "jpeg2ps sample.jpeg > filename.eps". Doing this will create the file "filename.eps" in the folder C:\Program Files\GnuWin32\bin. This will be your desired eps file. You can change the resolution as well as other options.

Enjoy!

More information:
How to convert quality jpeg images into eps. (Guage Invariance)

Timing backwards

2010-03-02T21:09:00.007-06:00

Let's assume we are watching 10 seconds of a basketball game. It is right at the moment when two players are standing near the basket and the ball is passed from one player to the other who reside under the basket. This player after, grabbing the ball, turns about his waist and shoots the ball into the basket such that the ball enters into the net from its below. We no longer see the game.

Now consider time goes backwards. The ball enters the basket from above, one player grabs it and passes it to the farther player. Consider the way how the players act is such that we cannot distinguish the difference between the first scenario and the second one only by watching their action.

It seems in the lack of the rest of the play, we cannot distinguish between these two degenerate scenarios. However, there is a tiny difference between the two that breaks the degeneracy. In fact, by noticing that we can distinguish between the correct and the backward time directions. Guess what is the point?

Mohammad H. Ansari

A new solution to the statistics of hard elongated objects

2009-11-29T23:42:00.002-06:00

A new solution to the statistics of hard elongated objects
M.Ansari, [0911.5312] (cond.mat/statistical Mechanics)

On: an analytical solution to the statistics of hard elongated objects (e.g. needles, rectangles, ellipses, etc)

Elasticity theory describes how a system under distortion is mechanically deformed. There are two approaches to quantitatively study this. The traditional approach is
to analyze the dislocation of fluid rigid boundaries. Depending on the properties of fluid (e.g. viscosity, compressibility, etc.) a variety of different cases appears.

The other approach, which is of our interest, replaces fluid with discrete objects and studies the short-range interaction between these objects. If the objects are spherically-symmetric, their alignments lead to translational ordered/disordered phases.

Frenkel et.al. in a series of papers developed a method that enables to analyze the stress and elasticity of hard spherically-symmetric objects.

A natural generalization is to replace the spherically-symmetric objects with elongated objects. These objects carry a coupling between their translational and rotational degrees of freedom and display orientational ordered/disordered phases; similar to liquid crystals.

Recently, in a series of papers a formalism for direct calculation of elastic properties of hard non-spherically symmetric objects was proposed by Murat, Kantor, and Farago. They considered hard stiffness for these objects in order to prevent the influence of orientational degrees of freedom into kinetic energy. Their method was
developed on the basis of different types of central and non-central short-range interactions; central potential depends only on the relative distance between particles, whereas noncentral potential depends on individual object orientations.

This formalism has been so far applied in different problems such as the wrapping of proteins in DNA, the ordering of complex liquids systems and percolation transitions, and the jamming transitions.

However, this formalism is hard to be solved analytically and a Monte-Carlo simulation should been used to extract its physical properties. Kantor and Kardar in
proposed a self-consistency check for this formalism in one dimension, where instead of non-spherically symmetric objects, needles are applied. The center of needles
are on a line and the angle of each needle orientation is randomly chosen. They solved this model by transfer matrix method numerically and reported an agreement
between the numerical and MC results.

The purpose of my recent publication is to reconsider elongated objects in one dimension and propose an analytical solution that, in our opinion, goes a step forward since it allows to obtain analytical formulation for some collective properties obtained so far only numerically.

To this end, we eliminate the dependence of free energy on the absolute value of an angle, thus make the orientation completely isotropic.

Interparticle distance and elasticity coefficients are derived into analytical formulations and verify the exact model results of Kardar and Kantor. We generalize our formalism to cover different types of elongated objects and repeat to derive them and verify recent results. This formalism allows to evaluate other properties of the same class, such as inverse distance between needles.

We verify the inverse distance law of sound pressure in high densities. As expected from a previous study on spherically-symmetric object, in needles model the expectation value of inverse distance below a critical pressure does not scale as the inverse of distance.

Energy released by Volcano and earthquake

2009-09-26T20:39:00.007-05:00

The energy released from a Volcano is 10^13 Joules. The chemical bond energy between carbon molecules to form 12 grams of carbon compound is typically 10^5 Joules. With the 10^13 Joules one can vaporize 10^3 Tonnes of Carbon.

In the case of an earthquake of magnitude 6, about 10^15 Joules of energy is released, some of these are released before the main shock. This amount is necessary to vaporize 10^5 Tonnes of carbon. Although most of the energy is released in the thermal form, but anyhow should it be unrealistic that one studies the formation of an earthquake cloud before an earthquake on top of the region gaining this energy.

P.S.> The above picture is taken from here.

Reports on NPB findings from M.H. Ansari and co-researchers provide new insights

2009-04-29T17:27:00.002-05:00

Source: VerticalNews Physics

May 5th, 2008

"Without imposing the trapping boundary conditions and only from within the very definition of area it is shown that the loop quantization of area manifests an unexpected degeneracy in area eigenvalues," researchers in Waterloo, Canada report.
"This could lead to a deeper understanding of the microscopic description of a quantum black hole," wrote M.H. Ansari and colleagues.

The researchers concluded: "If a certain number of semi-classically expected properties of black holes are imposed on a quantum surface its entropy coincides with the Bekenstein-Hawking entropy."

Ansari and colleagues published their study in NPB...

Classical and Quantum Geometry Conferences in 2009

2009-02-01T18:25:00.004-06:00

Very High Energy Phenomena Feb 1-8 La Thuile

http://moriond.in2p3.fr/J09/

Dark Matter Feb 2-6 CERN
http://indico.cern.ch/conferenceDisplay.py?confId=44160

Dark Matter Feb 9-11 Florence
http://ggi-www.fi.infn.it/index.php?p=events.inc&id=34

High-Freq Grav. Waves Feb 24-27 Huntsville

Dark Side of Gravity Mar 2-4 Florence
http://ggi-www.fi.infn.it//index.php?p=events.inc&id=40

New Directions in Cosmology Mar 16-20 Beijing tangxin@itp.ac.cn

Black Holes and LQG Mar 26-28 Valencia

http://www.uv.es/bhlqg/

25th Pacific Coast Meeting Mar 27-28 Eugene
http://www.tapir.caltech.edu/pcgm25/index.html

Intermediate-Mass Black Holes Apr 1-3 Irvine
http://www.physics.uci.edu/IMBH/

Non-Gaussianities Apr 6-8 Tokyo
http://ipmu.jp/seminars/20090406-focusweek.html

Grav09 Apr 13-17 Cordoba
http://www.famaf.unc.edu.ar/~gdotti/grg/grav09/grav09.htm

BritGrav 9 Apr 15-16 Cardiff
http://www.astro.cf.ac.uk/research/gravity/?page=britgrav

Grishchuk Fest Apr 17 Cardiff
http://www.astro.cf.ac.uk/research/gravity/

NAM/JENAM Meeting Apr 20-23 Hatfield

http://www.jenam2009.eu
(Grav Waves session 21)

Zeldovich 95th Apr 20-23 Minsk

http://www.icranet.org/zeldovich

Relativity in Astrometry Apr 27-May 1 Virginia Beach
http://www.aas.org/divisions/meetings/iau/

Black Holes VII May 9-15 Banff
http://fermi.phys.ualberta.ca/~gravity/BH7

GW+HEN Workshop May 18-20 Paris

http://www.gwhen-2009.org

Relativistic Astrophysics May 19-21 Atlanta
http://www.cra.gatech.edu/CenterConference/

Sobral Meeting May 26-29 Sobral secretariat@icranet.org

Chalonge Colloquoium May 28-29 Paris
http://chalonge.obspm.fr/colloque_ES2009.htm

Cosmological Magnetic Fields May 31-Jun 5 Ascona
http://theory.physics.unige.ch/CMF/

Standard Model of Universe Jun 4-5 Paris
http://chalonge.obspm.fr/colloque_ES2009.html

12th Eastern Gravity Meeting Jun 15-16 Rochester EGM2009@ccrg.rit.edu
http://ccrg.rit.edu/~EGM2009/

Mathematical Relativity Jun 18-19 Lisbon
http://www.math.ist.utl.pt/~jnatar/Mira/

21st Rencontres de Blois Jun 21-26 Blois
http://confs.obspm.fr/Blois2009/index.htm

Amaldi 8 Jun 21-26 New York amaldi8@gmail.com
http://www.amaldi8.org/

ICGA 9 Jun 28-Jul 1 Wuhan zhouzb@mail.hust.edu
http://ggg.hust.edu.cn/ICGA9/icga9.htm

Unity of the Universe Jun 29-Jul 1 Portsmouth
http://www.icg.port.ac.uk/sciama09/

Invisible Universe Jun 29-Jul 3 Paris
http://www.universe2009.obspm.fr

Marcel Grossmann MG12 Jul 12-18 Paris mg12@icra.it
http://www.icra.it/MG/mg12/

Chalonge: 13th Paris Cosmology Jul 23-25 Paris

http://chalonge.obspm.fr

CosmoSTATS09 JUl 26-31 Ascona
http://www.itp.uzh.ch/cosmostats

Loops '09 Aug 2-8 Beijing

IAU General Assembly Aug 3-14 Rio de Janeiro

Neutron Stars: IAU JD Aug 3-5 Rio de Janeiro

IAU2009extreme@brera.inaf.it
http://www.brera.inaf.it/IAU2009extreme/index.html

NIJMEGEN09 Aug 18-28 Nijmegen

http://nijmegen09.hef.kun.nl/

Grassmannian conference Sept 14-19 Szczecin
http://cosmo.fiz.univ.szczecin.pl

Challenges in Cosmology Sept 2-5 Talloires
http://cosmos.phy.tufts.edu/conference/

Space, Time and Beyond Oct 8-9 Golm
http://spacetimebeyond.aei.mpg.de/

Galileo - Xu Guangqi Oct 26-30 Shanghai
http://www.icranet.org/index.php?option=com_content&task=view&id=399&Itemid=686

Thanks to Malcolm MacCallum

Revewing a review on my work!

2009-01-13T19:42:00.014-06:00

In Mathematical Reviews, all of my papers so far have been reviewed. One of the reviews is more extensive and after reading that I felt it could be a good idea if I have the chance to review this review in Gauge Invariance blog. I thank Maria Cristina Abbati for writing the original review.

Let me emphasize this review by no mean is to criticize the original review as it is fair in its real meaning. Moreover, this paper under discussion has been already published in NPB a year ago and the review was written recently. The review written for Math Rev is only a way to explain, publicize and partially simplify the contents of the paper briefly. Mathematical Reviews is a large archive of Physics and Math papers where these papers are reviewed again to be resorted.

The original review is in green color. The red words in between are not so to criticize something. The are marked red only to make my review easy to read and conclude. The red words do not oppose anything in the green lines, as they are mostly after one another.

In a previous paper [M. Ansari, NPB 783 (2007), no. 3, 179--212; MR2356347], the author gave an accurate description of the spectrum of the area operator as it is defined in loop quantum gravity.

He improved on previous results in the area, gave a new minimum value of the area in Planck's area unit, a_{min} = (3^0.5) * 2 \pi \gamma (where \gamma is the Immirzi parameter), and found a classification of the spectrum as a union of equidistant subsets which he called generations.

[I should correct the first part of the 2nd paragraph. In that article, I have not tried to give any new minimum value to the area.

In fact, this minimum value of area was reported by Abhay Ashtekar and Jerzy Lewandowski. They reported a spectrum of area in 1996. A few months later, Carlo Rovelli and his colleague reported the same spectrum of area using a completely different technique. Later on, Thomas Thiemann also studied this spectrum in more details and reported the same spectrum for a quantum of area.

And Yes!, in that paper I reported a new classification of the specrum of area, the so-called ladder symmetry. In fact there exists a universal formula for area that is way more compact that the one reported originally.]

This paper is complementary to the above paper and contains a detailed analysis of the degeneracy of the area's eigenvalues. The numerical results for the first hundred levels of the spectrum are summarized in scatterplots. Taking into account the generating properties, the degeneracy for a large area is estimated and results in \Omega(A) = g(a_{min} ^N, where g(a_{min} is the degeneracy of the minimum value.

[Yes, I reported a hidden degeneracy as well as a ladder symmetry on area eigenvalues.

However, one should not mistake this "numerical result" mentioned here as an approximation to an analytical result. In fact, there is no numerical result in this work. Everything has been reported in terms of theorems and they are exact result. Recently, Takashi Tamaki extended this classification of area eigenvalues in a different way. I will give it a brief review in later posts in gauge invariance.]

A kinematical entropy S is assigned to each area value, defined as the log of its degeneration. Assuming that A=Na_{min} for a large area, the formula S=A log ( g(a_{min}) ) / a_{min} is obtained.

The formula is relevant when it is applied to the entropy of a non-rotating black hole and, compared with the Bekenstein-Hawking formula, determines the value of \gamma giving \gamma= log 3 / ( \pi 2^0.5 ) .

As the author remarks, he follows here the approach to black holes used by C. Rovelli (see the bibliography), where a surface in spacetime is initially considered and the expected properties of a black hole are imposed on its entropy at the semiclassical level. Another approach to black holes in loop quantum gravity was first studied by A. Ashtekar et al. [Phys. Rev. Lett. 80 (1998), no. 5, 904--907; MR1606489 (98k:83051)]. There, a boundary condition on spacetime was given at the classical level and the resulting Hamiltonian was quantized along the lines of loop quantization, giving a completely different kinematical space. In this approach the value for the Immirzi parameter is double Ansari's value.

[ The only notice to add here is that in the last sentence of above apargraph, one should note that this comparison is done in SO(3) group representations.]

A comparison of the two approaches is given by the author himself in the paper, but the question of the right black hole theory in loop quantum gravity and the value of the Immirzi parameter seems to be still open.

[ There is a main difference between the spin network black hole strategy, the one I studied in this paper, and the other opponent strategy that is called 'quantum isolated horizon picture.'

The difference is that in the latter picture one needs to *believe* that different parts of a black hole horizon are distinguishable from one another. If this is not assumed, one does not get the entropy proportional to area, instead it will be proportional to A^0.5. This is a strange fact that honestly is true! This distinguish-ability is an additional assumption and since 1996 till now nobody showed why should we assume this when the states associated with the Chern-Simons horizon does not show that as a quantum fact to us.

I neglectdiscussing the recent claims that the state of punctures are reported to be a sequence of punctures not a set of puncture. This assumption if is true generates an orderly difference between punctures, breaks a huge number of diffeomoerphism invariant class on the horizon and make each puncture distinguishable. However, there is no physical reason why should we prefer a sequence of punctures to a set of them. All of this seems to be passing a problem from distinguished states into an underlying diffeomorphism invariance breaking.

In the spin network black hole picture, which turns out to be a more quantum approach to understand a black hole, although the Thermodynamics of black hole and their evolutions have not been developed yet, but instead this picture does not suffer from the illness the other opponent suffers from. In other words, the entropy based on the degeneracy of spin network states is really proportional to the area A, and not A^0.5.

The reason is simple. The area operator when acts on the spin network states, it is in-sensitive to the completely tangential edges. The spin network states with different completely tangential edge states may belong to the same unification class of area eigenstates. However they may at the same time belong to completely different classes of other physical operators such as energy. As a consequence, any physical object that is described only by one parameter semi-classically, manifest area unification classes as a surface with distinguishable parts. In other words, two states with the same area that reside on a black hole horizon are distinguishable from one another only because their difference in their completely tangential edges, thus under the action of other operators they become recognizable. ]

Ice Crystal Patterns on My Home Window

2008-12-21T19:49:00.002-06:00

Today I was amazed by seeing the little funny crystals on the window of my home. The following picture show them.

From Guage Invariance Photoblog

What are these crystals?

My window has double pans, the outer one touches a freezing temperature and the inner one a comfortable high temperature of +25 Celsius. My living room heaters are right underneath that window, therefore the transmission of hot air around the window is high. Moist cools to water and gradually into ice on the outer glass.

When the outside temperature falls gradually, the water molecules have enough time to cool down less disorderedly and form a crystal. The water crystals are frosted based on the glass surface conditions. In fact, when a piece of glass is polished at the time it was made in the glass factory, or when we scrub its surfaceby soap or glass cleaners some hidden patterns are left on it. These patterns play an important role of being the main base to nucleate the way these frost crystals condensate and grow on the window.

The main question is where these symmetric flower patterns come from? To learn it, see here.

Below there are some more photo of my window:

From Guage Invariance Photoblog

Snow strom in Waterloo

2008-12-19T17:12:00.007-06:00

Today, I was excited in the morning. Finally the moment of having a real snow storm in our city has arrived! Interesting, because this was the only way to see Navier-Stocks equations in front of your eyes, specially when winds are blown out from the edge of a building. You see how the smooth wind fronts get hurly and produces the little funny curly wind flows right after the edges.

I took some pictures in the university that I put here some.

From Guage Invariance Photoblog

Scientific inquisition

2008-11-18T17:34:00.009-06:00

It is difficult to talk about the things that I like because you see them in my works. They are in my paintings, in my radio theaters, in my papers. It is easier for me to talk about things that I don't like. I mean I cannot describe what I like in words. They are more interesting than words.

But in all, I do not like to engage in telling some useless stories in my papers about towards this theory and that theory. I like to be mystified by physical world instead of ordering to the reality on how it should be. I don't like to arouse the readers of my papers emotionally or give them some advices about how should he or she study from now on. I don't like to belittle him or burden him with a sense of guilt that he or she is ignorant and there are a lot to learn before thinking about nature. These are things I don't like to read in papers written by others as well. I think a good paper is one that has a lasting power and you start to reconstruct it right after you leave reading it.

There are lots of papers that seem to be boring but they are decent pieces of science. On the other hand, there are papers written by sometimes famous people that nail you to your seat in your office when you read it and overwhelm you to the point that you forget everything. I have experienced this feeling in the near past and now I feel I am cheated. These are the well-written papers that took me hostage! I absolutely don't like the papers in which the scientist provoke his or her readers with some fake calculations that artificially describe what was raised by that great mind in a seminar as an imaginary problem of some imaginary concepts.

I have to confess there are some papers in my office right now that have made me doze off when I read them, but the same papers have made me stay up at night, wake up thinking about them in the morning and keep on thinking about them for weeks. Those are the kind of papers I like.

I have imaginations but there are differences between illusion and reality. Not everything I imagine will be found in nature even if they are linked to theoretical physics. I can't tell you what part of me is reality and what part is illusion, or why I've had this game of vacillation from reality to illusion and back to reality in my ordinary life, not necessarily as a physicist. The capacity to dream is the most important human characteristic, shared not proportionality but enough for each. Though all of us dream, only a very few of us can write it in the form of formulae.

Imagination is one of the most extraordinary gifts granted to human beings. But, why must we dream? I think, we resort to dreaming at times when we are unhappy with our circumstances. And how extraordinary is it that no dictatorship in research institutions can control it?

Obviously there is a scientific inquisition running in some of the academic research institutes even where freedom in science is being advertised from. However, it is surely true these only can affect the most boring part of science. No interesting part that really exists let the scientific inquisition control a true scientist's fantasies. They can throw you in a jail (i. e. a dark well) of ideas, but you still have the ability to live your sentence outside the prison without anyone holding you there. Through the imagination, you can pass over the insurmountable walls of stupid ideas without leaving any trace of yourself, and you can always go back. Now the question is, once out why we go back?

Entropy of a Research Center

2008-10-24T12:35:00.021-05:00

In an interview with Martinus Veltman back to 1999 hosted in the Nobel Prize Organization website, Veltman talks about differences in the educational systems of Europe and USA in the first two minutes. It goes this way:

Interviewer: What was a difference between being a student today and the time when you were a student?

Veltman: It was less disciplined [then]. In my student era you could do nothing for a few years. And you start working again, and I liked that a lot and I did nothing for a number of years. But today in Europe, it is no more possible because they stop supporting you and so on. They made the system such that you cannot do it.

I am strongly in favor of a system in which someone can momentarily go out and later on come back again, for whatever reason; maybe he is not mature enough or maybe he wants to have other experiences. That was [possible] in a system of my time. Today, it is no more possible, it is very difficult.

Given that such a freedom is necessary to create new science, unfortunately what he says and we are experiencing is a lack of free-thinking in today's science.

I personally have no professional academic experience in my home country Iran to be in a University as a faculty member but from what I heard from friends, I think, this is still possible one can do nothing for a number of years without being kicked out of the University in Iran. I hope they keep up the good job!

However, there are some model research institutes in Iran that are supposed to percolate the body of Iranian science within universities and these Institutes seems to be very well disciplined. This is unfortunate because if anywhere else in the world must become more and more disciplined, this should be the other way around and the entropy should get raised inside research institutions. A scientist needs new ideas to be extracted from a Hurley burly of thoughts.

Learning Ethics in a few months!

2008-09-18T08:54:00.057-05:00

My life went into a terrible crisis for a few months that I have lost a research job because of the resignation of my nominal postdoctoral mentor. In less than two months until starting that research job and during the time I was working on my defence and marriage travel plans and expenses, I suddenly was informed of this change. But this enlightened me with some new ideas.

There are a few people including scientists who do not keep their promises and invitation letters. Anyways, in a few weeks I concentrated on what should I do. Today, I received an interesting offer from C&O at Waterloo to start a different position int there. I could not imagine how interesting these scientists at C&O are! Very active seminars, interesting research subjects and precise in wording mathematical ideas. Today I transferred my Homepage into this new server.

I am grateful that I am paused on learning science for a few month during this turmoil and instead I understood how important is Ethics for scientists. I learned not every scientist knows about its importance.

Sometimes there is no law for something to obey and it is ours to adjust ourselves with our nature (that matches the external Ethical laws). For instance, there is no law to realize the most appropriate sound volume of music in a car. The decision is ours and depends on the situation we are in. We should check if somebody is taking a nape or if there is a passenger whose hearing aids may get serious damages from listening to a loud music. Having these inputs, we decide. This is ethics, not law.

Similarly, consider one checks the permission of breaking a contract letter only and only with related officers of companies or universities and as soon as it is realized it is not illegal, one immediately takes it into action and breaks it, no matter how this may damage others. Neglecting how our desires might be harmful for others, if is even legal certainly, it is not ethical.

Tusi is a wonderful scientists whose books should be read by every scientist and student, especially Tusi's very short paper on ethics which is only 3 pages but it is, to be honest, a treasure of words and wisdom.Tusi was the chair of the Maraqeh research institute in Iran 400 years before Galilei.

Given that I do not like to recall the crisis I was in during the last few months, the structure of my scientific character is now blessed by knowing the importance of ethical behaviour and that a scientist no matter how smart he or she is needs to gain some cultural background.

Tusi on page 1, the sentence 4 says:

Do not test men of science with the abundance of knowledge, but respect their condition by refraining from evil and mischief.

Tusi says on sentence number 18 of the same paper:

Recognize that Man's vileness derives from his speaking much to no purpose, and know him from his declarations on things that do not concern him.

Tusi was living 8 centuries ago in Iran. He has proved many mathematical theorems including the Tusi couple and many other original models and proofs. He was living at the time when Monglians attacked Iran and occupied it.

Mohammad

Gravity in small scales (Part 1 - Tradiational Gravity)

2008-05-13T22:19:00.013-05:00

By: Mohammad H. Ansari

What sort of laws shape the universe? The answer is given by understanding two
things: 1) what is space-time, 2) what is the dynamics of space-time.

The first question has no unique answer. In fact, there could be many answers to it, among some of which are: metric fields, frame fields and connections, causal sets, causal sites, strings, topological fields, spin networks, etc. Usually any reasonable assumption for simplifying a physical system such as space-time is acceptable as long as its dynamics satisfies some physical facts. What makes a theory successful is mostly its dynamics.

So far there have been many different models for studying space-time dynamics in quantum scales; from perturbative to non-perturbative and also from continuum to discretized ones.

The traditional quantum gravity started with fixing a background metric and defining quantum effects as the perturbations of background metric. The diffeomorphism constraint is linearized and it appears to be solvable. This theory in this format becomes similar to a local field theory with two degrees of freedom defined at each point. The Feynman rules for constructing the diagrams are obtained from the Einstein-Hilbert Lagrangian coupled to matter using standard procedures of quantum field theory.

Comparing to other field theories, in this localized field theory of gravity the perturbative part of metric turns out to interact with itself on the fixed background by some additional derivatives. This suggests the interaction coefficient to be of length dimension.

Quantum field theory of gravity has an infinite number of complicated interaction vertices. Where the momentum of the internal loop propagator becomes arbitrary large the loop diagrams diverge. In other theories such as chromodynamics the similar UV divergences appear; however those theories are renormalizable. Renormalizability means that the divergences from high energy scales can be absorbed into the redefinition of original parameters appearing in the theory. However, in the quantum field theory of gravity, we cannot eliminate UV divergences in the original Lagrangian because the gravity coupling G carries dimension of length.

To be continued ...

The Intelligent Village

2008-04-16T22:29:00.005-05:00

The following Bulgarian Animation by Donyo Donev explains one of the most common problems in quantum gravity papers for years now. Somebody makes a model. It contradicts a classical fact. It is modified. It breaks something. It gets modified. It is redone again and again for several times. Finally, the initial problem for whose solution the initial assumption was made is forced to be back to the theory. It is back and resolves some post-created problems but yet there exists the main problem there.

How to convert jpeg images into eps?

2008-04-02T10:56:00.008-05:00

If you use windows to write LaTeX files (by editors like WinEdit etc.) you may feel that it is terribly hard to find an effective way to convert a picture with format jpeg, bmp, etc into the appropriate format of LaTex, which is eps.

If you google it you will get many softwares which are mostly non-free. I tried several of them and faced with funny problems. For instant when you convert a picture in one of them, it does it on its trial version but it stamps (!) the outcome eps picture with a very large signature of their company, which makes the picture useless. Another software convert it with very poor quality in its trial version, etc.

I found two simple way to overcome this problem.

First method:

1- First install GSview and GhostScript from this page on your windows.

2- Download the humble, effective and small software called "jpeg2ps" that let you convert jpeg to eps with acceptable quality (and you can increase its quality manually). jpeg2ps is available from here and many other sites, notably CTAN mirrors.

UPDATE: If you are lost and do not know how to work with jpeg2ps software in Windows, read my jpeg2ps pedagogical helps on it.

Second method:

1- First install GSview and GhostScript from this page on your windows.

2- Install the driver of a Postscript printer (denoted by a "PS" at the end of the printer name. This can be done as follows: Start -> Control Panel -> Printers -> Add printer. Press next a couple of times until you reach the page where you can choose between different manufacturers. Choose a Postscript printer.) I have chosen the printer "Apple Color LW 12/660 PS."

3- Now come back to My Computer and find the picture you want to convert. Right click on it and press Edit, or you Open With - > Paint. If you do not know what Paint is, go to Start -> Accessories -> Paint. Now, File -> Print. Choose the printer you just installed. Tick on "Print to a file." Click on the printer Preferences - > Advanced. Where there is "PostScript Option" in the tree diagram, click on the little + sign next to it such that you see its sub-branches. In the "PosScript Output" change the default which might be Optimized for Speed into "Encapsulated Post Script (EPS)." You also can play with other features and properties to change the quality of the outcome EPS picture. Then OK everything and choose a name for the outcoming file. It will be created at the same foldr as the original file was in.

Enjoy!

More information:

How to work with jpeg2ps software in Windows? (Gauge Invariance)

Area, ladder symmetry, degeneracy and fluctuations of a horizon

2007-11-14T17:03:00.000-06:00

By: Mohammad H. Ansari

My latest article about the fluctuations of a horizon was finished: abs/0711.1879

What is new?

After introducing ladder symmetry and degenerate state in area operator of loop quantum gravity, ...

based on a more precise method it is shown

... a few of harmonic modes appear to be extremely amplified on top of the Hawking's radiation. They are expected to form a few brightest lines with the wavelength not larger than the black hole size.

Politics and the English Language

2007-10-03T19:55:00.001-05:00

By George Orwell, 1946
Listen (16 Mb)

Most people who bother with the matter at all would admit that the English language is in a bad way, but it is generally assumed that we cannot by conscious action do anything about it. Our civilization is decadent and our language — so the argument runs — must inevitably share in the general collapse. It follows that any struggle against the abuse of language is a sentimental archaism, like preferring candles to electric light or hansom cabs to aeroplanes. Underneath this lies the half-conscious belief that language is a natural growth and not an instrument which we shape for our own purposes.

Language becomes ugly and inaccurate because our thoughts are foolish, but the slovenliness of our language makes it easier for us to have foolish thoughts.

Now, it is clear that the decline of a language must ultimately have political and economic causes: it is not due simply to the bad influence of this or that individual writer. But an effect can become a cause, reinforcing the original cause and producing the same effect in an intensified form, and so on indefinitely. A man may take to drink because he feels himself to be a failure, and then fail all the more completely because he drinks. It is rather the same thing that is happening to the English language. It becomes ugly and inaccurate because our thoughts are foolish, but the slovenliness of our language makes it easier for us to have foolish thoughts.

The point is that the process is reversible. Modern English, especially written English, is full of bad habits which spread by imitation and which can be avoided if one is willing to take the necessary trouble. If one gets rid of these habits one can think more clearly, and to think clearly is a necessary first step toward political regeneration: so that the fight against bad English is not frivolous and is not the exclusive concern of professional writers. I will come back to this presently, and I hope that by that time the meaning of what I have said here will have become clearer. Meanwhile, here are five specimens of the English language as it is now habitually written.

Examples of poor language

These five passages have not been picked out because they are especially bad — I could have quoted far worse if I had chosen — but because they illustrate various of the mental vices from which we now suffer. They are a little below the average, but are fairly representative examples. I number them so that I can refer back to them when necessary:

I am not, indeed, sure whether it is not true to say that the Milton who once seemed not unlike a seventeenth-century Shelley had not become, out of an experience ever more bitter in each year, more alien [sic] to the founder of that Jesuit sect which nothing could induce him to tolerate. (return)
~ Professor Harold Laski (Essay in
Freedom of Expression)
Above all, we cannot play ducks and drakes with a native battery of idioms which prescribes egregious collocations of vocables as the Basic put up with for tolerate, or put at a loss for bewilder. (return)
~ Professor Lancelot Hogben
(Interglossia)
On the one side we have the free personality: by definition it is not neurotic, for it has neither conflict nor dream. Its desires, such as they are, are transparent, for they are just what institutional approval keeps in the forefront of consciousness; another institutional pattern would alter their number and intensity; there is little in them that is natural, irreducible, or culturally dangerous. But on the other side, the social bond itself is nothing but the mutual reflection of these self-secure integrities. Recall the definition of love. Is not this the very picture of a small academic? Where is there a place in this hall of mirrors for either personality or fraternity? (return)
~ Essay on psychology in
Politics (New York)
All the ‘best people’ from the gentlemen's clubs, and all the frantic fascist captains, united in common hatred of Socialism and bestial horror at the rising tide of the mass revolutionary movement, have turned to acts of provocation, to foul incendiarism, to medieval legends of poisoned wells, to legalize their own destruction of proletarian organizations, and rouse the agitated petty-bourgeoise to chauvinistic fervor on behalf of the fight against the revolutionary way out of the crisis. (return)
~ Communist pamphlet
If a new spirit is to be infused into this old country, there is one thorny and contentious reform which must be tackled, and that is the humanization and galvanization of the B.B.C. Timidity here will bespeak canker and atrophy of the soul. The heart of Britain may be sound and of strong beat, for instance, but the British lion's roar at present is like that of Bottom in Shakespeare's A Midsummer Night's Dream — as gentle as any sucking dove. A virile new Britain cannot continue indefinitely to be traduced in the eyes or rather ears, of the world by the effete languors of Langham Place, brazenly masquerading as ‘standard English’. When the Voice of Britain is heard at nine o'clock, better far and infinitely less ludicrous to hear aitches honestly dropped than the present priggish, inflated, inhibited, school-ma'amish arch braying of blameless bashful mewing maidens!(return)
~ Letter in Tribune

Each of these passages has faults of its own, but, quite apart from avoidable ugliness, two qualities are common to all of them. The first is staleness of imagery; the other is lack of precision. The writer either has a meaning and cannot express it, or he inadvertently says something else, or he is almost indifferent as to whether his words mean anything or not.

This mixture of vagueness and sheer incompetence is the most marked characteristic of modern English prose, and especially of any kind of political writing. As soon as certain topics are raised, the concrete melts into the abstract and no one seems able to think of turns of speech that are not hackneyed: prose consists less and less of words chosen for the sake of their meaning, and more and more of phrases tacked together like the sections of a prefabricated hen-house.

The worst offenders

I list below, with notes and examples, various of the tricks by means of which the work of prose-construction is habitually dodged.

Dying metaphors

A newly invented metaphor assists thought by evoking a visual image, while on the other hand a metaphor which is technically ‘dead’ (e. g. iron resolution) has in effect reverted to being an ordinary word and can generally be used without loss of vividness. But in between these two classes there is a huge dump of worn-out metaphors which have lost all evocative power and are merely used because they save people the trouble of inventing phrases for themselves.

Examples are:

ring the changes on
take up the cudgel for
toe the line
ride roughshod over
stand shoulder to shoulder with
play into the hands of
no axe to grind
grist to the mill
fishing in troubled waters
on the order of the day
Achilles’ heel
swan song
hotbed

Many of these are used without knowledge of their meaning (what is a ‘rift’, for instance?), and incompatible metaphors are frequently mixed, a sure sign that the writer is not interested in what he is saying.

Some metaphors now current have been twisted out of their original meaning without those who use them even being aware of the fact. For example, toe the line is sometimes written as tow the line. Another example is the hammer and the anvil, now always used with the implication that the anvil gets the worst of it. In real life it is always the anvil that breaks the hammer, never the other way about: a writer who stopped to think what he was saying would avoid perverting the original phrase.

Operators or verbal false limbs

These save the trouble of picking out appropriate verbs and nouns, and at the same time pad each sentence with extra syllables which give it an appearance of symmetry. Characteristic phrases are:

render inoperative
militate against
make contact with
be subjected to
give rise to
give grounds for
have the effect of
play a leading part (role) in
make itself felt
take effect
exhibit a tendency to
serve the purpose of

The keynote is the elimination of simple verbs. Instead of being a single word, such as break, stop, spoil, mend, kill, a verb becomes a phrase, made up of a noun or adjective tacked on to some general-purpose verb such as prove, serve, form, play, render. In addition, the passive voice is wherever possible used in preference to the active, and noun constructions are used instead of gerunds (by examination of instead of by examining).

The range of verbs is further cut down by means of the -ize and de- formations, and the banal statements are given an appearance of profundity by means of the not un- formation. Simple conjunctions and prepositions are replaced by such phrases as:

with respect to,
having regard to,
the fact that,
by dint of,
in view of,
in the interests of,
on the hypothesis that;

...and the ends of sentences are saved by anticlimax by such resounding
commonplaces as:

greatly to be desired,
cannot be left out of account,
a development to be expected in the near future,
deserving of serious consideration,
brought to a satisfactory conclusion;

...and so on and so forth.

Pretentious diction

Words like:

phenomenon,
element,
individual (as noun),
objective,
categorical,
effective,
virtual,
basic,
primary,
promote,
constitute,
exhibit,
exploit,
utilize,
eliminate,
liquidate;

...are used to dress up a simple statement and give an air of scientific impartiality to biased judgements. Adjectives like:

epoch-making,
epic,
historic,
unforgettable,
triumphant,
age-old,
inevitable,
inexorable,
veritable;

...are used to dignify the sordid process of international politics, while writing that aims at glorifying war usually takes on an archaic colour, its characteristic words being:

realm,
throne,
chariot,
mailed fist,
trident,
sword,
shield,
buckler,
banner,
jackboot,
clarion.

Foreign words and expressions such as cul de sac, ancien regime, deus ex machina, mutatis mutandis, status quo, gleichschaltung, weltanschauung, are used to give an air of culture and elegance. Except for the useful abbreviations i.e., e.g. and etc., there is no real need for any of the hundreds of foreign phrases now current in the English language. Bad writers, and especially scientific, political, and sociological writers, are nearly always haunted by the notion that Latin or Greek words are grander than Saxon ones, and unnecessary words like expedite, ameliorate, predict, extraneous, deracinated, clandestine, subaqueous, and hundreds of others constantly gain ground from their Anglo-Saxon numbers (See appendix 1).

The jargon peculiar to Marxist writing (hyena, hangman, cannibal, petty bourgeois, these gentry, lackey, flunkey, mad dog, White Guard, etc.) consists largely of words translated from Russian, German, or French; but the normal way of coining a new word is to use Latin or Greek root with the appropriate affix and, where necessary, the size formation. It is often easier to make up words of this kind (deregionalize, impermissible, extramarital, non-fragmentary and so forth) than to think up the English words that will cover one's meaning. The result, in general, is an increase in slovenliness and vagueness.

Meaningless words

In certain kinds of writing, particularly in art criticism and literary criticism, it is normal to come across long passages which are almost completely lacking in meaning (See appendix 2). Words like romantic, plastic, values, human, dead, sentimental, natural, vitality, as used in art criticism, are strictly meaningless, in the sense that they not only do not point to any discoverable object, but are hardly ever expected to do so by the reader. When one critic writes, ‘The outstanding feature of Mr. X's work is its living quality’, while another writes, ‘The immediately striking thing about Mr. X's work is its peculiar deadness’, the reader accepts this as a simple difference opinion. If words like black and white were involved, instead of the jargon words dead and living, he would see at once that language was being used in an improper way.

Many political words are similarly abused. The word Fascism has now no meaning except in so far as it signifies ‘something not desirable’. The words democracy, socialism, freedom, patriotic, realistic, justice have each of them several different meanings which cannot be reconciled with one another. In the case of a word like democracy, not only is there no agreed definition, but the attempt to make one is resisted from all sides. It is almost universally felt that when we call a country democratic we are praising it: consequently the defenders of every kind of regime claim that it is a democracy, and fear that they might have to stop using that word if it were tied down to any one meaning.

Words of this kind are often used in a consciously dishonest way. That is, the person who uses them has his own private definition, but allows his hearer to think he means something quite different. Statements like:

Marshal Petain was a true patriot,
The Soviet press is the freest in the world,
The Catholic Church is opposed to persecution;

...are almost always made with intent to deceive. Other words used in variable meanings, in most cases more or less dishonestly, are: class, totalitarian, science, progressive, reactionary, bourgeois, equality.

A move away from concreteness

Now that I have made this catalogue of swindles and perversions, let me give another example of the kind of writing that they lead to. This time it must of its nature be an imaginary one. I am going to translate a passage of good English into modern English of the worst sort. Here is a well-known verse from Ecclesiastes:

I returned and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all.

Here it is in modern English:

Objective considerations of contemporary phenomena compel the conclusion that success or failure in competitive activities exhibits no tendency to be commensurate with innate capacity, but that a considerable element of the unpredictable must invariably be taken into account.

This is a parody, but not a very gross one. Example 3 above, for instance, contains several patches of the same kind of English. It will be seen that I have not made a full translation. The beginning and ending of the sentence follow the original meaning fairly closely, but in the middle the concrete illustrations — race, battle, bread — dissolve into the vague phrases ‘success or failure in competitive activities’. This had to be so, because no modern writer of the kind I am discussing — no one capable of using phrases like ‘objective considerations of contemporary phenomena’ — would ever tabulate his thoughts in that precise and detailed way. The whole tendency of modern prose is away from concreteness.

Now analyze these two sentences a little more closely. The first contains forty-nine words but only sixty syllables, and all its words are those of everyday life. The second contains thirty-eight words of ninety syllables: eighteen of those words are from Latin roots, and one from Greek. The first sentence contains six vivid images, and only one phrase (‘time and chance’) that could be called vague. The second contains not a single fresh, arresting phrase, and in spite of its ninety syllables it gives only a shortened version of the meaning contained in the first. Yet without a doubt it is the second kind of sentence that is gaining ground in modern English.

I do not want to exaggerate. This kind of writing is not yet universal, and outcrops of simplicity will occur here and there in the worst-written page. Still, if you or I were told to write a few lines on the uncertainty of human fortunes, we should probably come much nearer to my imaginary sentence than to the one from Ecclesiastes.

The debasement of language

As I have tried to show, modern writing at its worst does not consist in picking out words for the sake of their meaning and inventing images in order to make the meaning clearer. It consists in gumming together long strips of words which have already been set in order by someone else, and making the results presentable by sheer humbug. The attraction of this way of writing is that it is easy. It is easier — even quicker, once you have the habit — to say In my opinion it is not an unjustifiable assumption that than to say I think. If you use ready-made phrases, you not only don't have to hunt about for the words; you also don't have to bother with the rhythms of your sentences since these phrases are generally so arranged as to be more or less euphonious.

By using stale metaphors, similes, and idioms, you save much mental effort, at the cost of leaving your meaning vague, not only for your reader but for yourself.

When you are composing in a hurry — when you are dictating to a stenographer, for instance, or making a public speech — it is natural to fall into a pretentious, Latinized style. Tags like a consideration which we should do well to bear in mind or a conclusion to which all of us would readily assent will save many a sentence from coming down with a bump. By using stale metaphors, similes, and idioms, you save much mental effort, at the cost of leaving your meaning vague, not only for your reader but for yourself.

This is the significance of mixed metaphors. The sole aim of a metaphor is to call up a visual image. When these images clash — as in The Fascist octopus has sung its swan song, the jackboot is thrown into the melting pot — it can be taken as certain that the writer is not seeing a mental image of the objects he is naming; in other words he is not really thinking.

Look again at the examples I gave at the beginning of this essay. Professor Laski (Example 1) uses five negatives in fifty three words. One of these is superfluous, making nonsense of the whole passage, and in addition there is the slip — alien for akin — making further nonsense, and several avoidable pieces of clumsiness which increase the general vagueness.

Professor Hogben (Example 2) plays ducks and drakes with a battery which is able to write prescriptions, and, while disapproving of the everyday phrase put up with, is unwilling to look egregious up in the dictionary and see what it means.

Example 3, if one takes an uncharitable attitude towards it, is simply meaningless: probably one could work out its intended meaning by reading the whole of the article in which it occurs. In Example 4, the writer knows more or less what he wants to say, but an accumulation of stale phrases chokes him like tea leaves blocking a sink.

In Example 5, words and meaning have almost parted company. People who write in this manner usually have a general emotional meaning — they dislike one thing and want to express solidarity with another — but they are not interested in the detail of what they are saying. A scrupulous writer, in every sentence that he writes, will ask himself at least four questions, thus: What am I trying to say? What words will express it? What image or idiom will make it clearer? Is this image fresh enough to have an effect? And he will probably ask himself two more: Could I put it more shortly? Have I said anything that is avoidably ugly?

But you are not obliged to go to all this trouble. You can shirk it by simply throwing your mind open and letting the ready-made phrases come crowding in. They will construct your sentences for you — even think your thoughts for you, to a certain extent — and at need they will perform the important service of partially concealing your meaning even from yourself. It is at this point that the special connection between politics and the debasement of language becomes clear.

Insincere language and its uses

In our time it is broadly true that political writing is bad writing. Where it is not true, it will generally be found that the writer is some kind of rebel, expressing his private opinions and not a ‘party line’. Orthodoxy, of whatever colour, seems to demand a lifeless, imitative style. The political dialects to be found in pamphlets, leading articles, manifestos, White papers and the speeches of undersecretaries do, of course, vary from party to party, but they are all alike in that one almost never finds in them a fresh, vivid, homemade turn of speech.

When one watches some tired hack on the platform mechanically repeating the familiar phrases one often has a curious feeling that one is not watching a live human being but some kind of dummy.

When one watches some tired hack on the platform mechanically repeating the familiar phrases — bestial, atrocities, iron heel, bloodstained tyranny, free peoples of the world, stand shoulder to shoulder — one often has a curious feeling that one is not watching a live human being but some kind of dummy: a feeling which suddenly becomes stronger at moments when the light catches the speaker's spectacles and turns them into blank discs which seem to have no eyes behind them.

And this is not altogether fanciful. A speaker who uses that kind of phraseology has gone some distance toward turning himself into a machine. The appropriate noises are coming out of his larynx, but his brain is not involved, as it would be if he were choosing his words for himself. If the speech he is making is one that he is accustomed to make over and over again, he may be almost unconscious of what he is saying, as one is when one utters the responses in church. And this reduced state of consciousness, if not indispensable, is at any rate favourable to political conformity.

In our time, political speech and writing are largely the defence of the indefensible. Things like the continuance of British rule in India, the Russian purges and deportations, the dropping of the atom bombs on Japan, can indeed be defended, but only by arguments which are too brutal for most people to face, and which do not square with the professed aims of the political parties. Thus political language has to consist largely of euphemism, question-begging and sheer cloudy vagueness.

Defenceless villages are bombarded from the air, the inhabitants driven out into the countryside, the cattle machine-gunned, the huts set on fire with incendiary bullets: this is called pacification. Millions of peasants are robbed of their farms and sent trudging along the roads with no more than they can carry: this is called transfer of population or rectification of frontiers. People are imprisoned for years without trial, or shot in the back of the neck or sent to die of scurvy in Arctic lumber camps: this is called elimination of unreliable elements.

Such phraseology is needed if one wants to name things without calling up mental pictures of them. Consider for instance some comfortable English professor defending Russian totalitarianism. He cannot say outright, ‘I believe in killing off your opponents when you can get good results by doing so’. Probably, therefore, he will say something like this:

‘While freely conceding that the Soviet regime exhibits certain features which the humanitarian may be inclined to deplore, we must, I think, agree that a certain curtailment of the right to political opposition is an unavoidable concomitant of transitional periods, and that the rigors which the Russian people have been called upon to undergo have been amply justified in the sphere of concrete achievement.’

The inflated style itself is a kind of euphemism. A mass of Latin words falls upon the facts like soft snow, blurring the outline and covering up all the details. The great enemy of clear language is insincerity. When there is a gap between one's real and one's declared aims, one turns as it were instinctively to long words and exhausted idioms, like a cuttlefish spurting out ink.

In our age there is no such thing as ‘keeping out of politics’. All issues are political issues, and politics itself is a mass of lies, evasions, folly, hatred, and schizophrenia. When the general atmosphere is bad, language must suffer. I should expect to find — this is a guess which I have not sufficient knowledge to verify — that the German, Russian and Italian languages have all deteriorated in the last ten or fifteen years, as a result of dictatorship.

The invasion of ready-made phrases

But if thought corrupts language, language can also corrupt thought. A bad usage can spread by tradition and imitation even among people who should and do know better. The debased language that I have been discussing is in some ways very convenient. Phrases like a not unjustifiable assumption, leaves much to be desired, would serve no good purpose, a consideration which we should do well to bear in mind, are a continuous temptation, a packet of aspirins always at one's elbow.

Look back through this essay, and for certain you will find that I have again and again committed the very faults I am protesting against. By this morning's post I have received a pamphlet dealing with conditions in Germany. The author tells me that he ‘felt impelled’ to write it. I open it at random, and here is almost the first sentence I see:

‘[The Allies] have an opportunity not only of achieving a radical transformation of Germany's social and political structure in such a way as to avoid a nationalistic reaction in Germany itself, but at the same time of laying the foundations of a co-operative and unified Europe.’

You see, he ‘feels impelled’ to write — feels, presumably, that he has something new to say — and yet his words, like cavalry horses answering the bugle, group themselves automatically into the familiar dreary pattern. This invasion of one's mind by ready-made phrases (lay the foundations, achieve a radical transformation) can only be prevented if one is constantly on guard against them, and every such phrase anaesthetizes a portion of one's brain.

Silly words and expressions have often disappeared, not through any evolutionary process but owing to the conscious action of a minority.

I said earlier that the decadence of our language is probably curable. Those who deny this would argue, if they produced an argument at all, that language merely reflects existing social conditions, and that we cannot influence its development by any direct tinkering with words and constructions. So far as the general tone or spirit of a language goes, this may be true, but it is not true in detail. Silly words and expressions have often disappeared, not through any evolutionary process but owing to the conscious action of a minority. Two recent examples were explore every avenue and leave no stone unturned, which were killed by the jeers of a few journalists.

There is a long list of flyblown metaphors which could similarly be got rid of if enough people would interest themselves in the job; and it should also be possible to laugh the not un- formation out of existence (See appendix 3), to reduce the amount of Latin and Greek in the average sentence, to drive out foreign phrases and strayed scientific words, and, in general, to make pretentiousness unfashionable. But all these are minor points. The defence of the English language implies more than this, and perhaps it is best to start by saying what it does not imply.

The defence of the English language

To begin with it has nothing to do with archaism, with the salvaging of obsolete words and turns of speech, or with the setting up of a ‘standard English’ which must never be departed from. On the contrary, it is especially concerned with the scrapping of every word or idiom which has outworn its usefulness. It has nothing to do with correct grammar and syntax, which are of no importance so long as one makes one's meaning clear, or with the avoidance of Americanisms, or with having what is called a ‘good prose style’.

What is above all needed is to let the meaning choose the word, and not the other way around.

On the other hand, it is not concerned with fake simplicity and the attempt to make written English colloquial. Nor does it even imply in every case preferring the Saxon word to the Latin one, though it does imply using the fewest and shortest words that will cover one's meaning. What is above all needed is to let the meaning choose the word, and not the other way around.

In prose, the worst thing one can do with words is surrender to them. When you think of a concrete object, you think wordlessly, and then, if you want to describe the thing you have been visualising you probably hunt about until you find the exact words that seem to fit it. When you think of something abstract you are more inclined to use words from the start, and unless you make a conscious effort to prevent it, the existing dialect will come rushing in and do the job for you, at the expense of blurring or even changing your meaning.

Probably it is better to put off using words as long as possible and get one's meaning as clear as one can through pictures and sensations. Afterward one can choose — not simply accept — the phrases that will best cover the meaning, and then switch round and decide what impressions one's words are likely to make on another person. This last effort of the mind cuts out all stale or mixed images, all prefabricated phrases, needless repetitions, and humbug and vagueness generally.

But one can often be in doubt about the effect of a word or a phrase, and one needs rules that one can rely on when instinct fails. I think the following rules will cover most cases:

Never use a metaphor, simile, or other figure of speech which you are used
to seeing in print.
Never use a long word where a short one will do.
If it is possible to cut a word out, always cut it out.
Never use the passive where you can use the active.
Never use a foreign phrase, a scientific word, or a jargon word if you can think of an everyday English equivalent.
Break any of these rules sooner than say anything outright barbarous.

These rules sound elementary, and so they are, but they demand a deep change of attitude in anyone who has grown used to writing in the style now fashionable. One could keep all of them and still write bad English, but one could not write the kind of stuff that I quoted in those five specimens at the beginning of this article.

Simplifying English

Political language is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind.

I have not here been considering the literary use of language, but merely language as an instrument for expressing and not for concealing or preventing thought. Stuart Chase and others have come near to claiming that all abstract words are meaningless, and have used this as a pretext for advocating a kind of political quietism. Since you don't know what Fascism is, how can you struggle against Fascism? One need not swallow such absurdities as this, but one ought to recognise that the present political chaos is connected with the decay of language, and that one can probably bring about some improvement by starting at the verbal end.

If you simplify your English, you are freed from the worst follies of orthodoxy. You cannot speak any of the necessary dialects, and when you make a stupid remark its stupidity will be obvious, even to yourself. Political language — and with variations this is true of all political parties, from Conservatives to Anarchists — is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind.

One cannot change this all in a moment, but one can at least change one's own habits, and from time to time one can even, if one jeers loudly enough, send some worn-out and useless phrase — some jackboot, Achilles’ heel, hotbed, melting pot, acid test, veritable inferno, or other lump of verbal refuse — into the dustbin where it belongs.

Appendix

An interesting illustration of this is the way in which the English flower names which were in use till very recently are being ousted by Greek ones, snapdragon becoming antirrhinum, forget-me-not becoming myosotis, etc. It is hard to see any practical reason for this change of fashion: it is probably due to an instinctive turning-away from the more homely word and a vague feeling that the Greek word is scientific. (return)
Example: ‘Comfort's catholicity of perception and image, strangely Whitmanesque in range, almost the exact opposite in aesthetic compulsion, continues to evoke that trembling atmospheric accumulative ginting at a cruel, an inexorably selene timelessness... Wrey Gardiner scores by aiming at simple bull's-eyes with precision. Only they are not so simple, and through this contented sadness runs more than the surface bitter-sweet of resignation’. (Poetry Quarterly). (return)
One can cure oneself of the not un- formation by memorizing this sentence: A not unblack dog was chasing a not unsmall rabbit across a not ungreen field. (return)

By George Orwell, 1946

George Orwell
(1903-1950) was a noted British writer and journalist, and one of the most gifted cultural commentators of the 20th century. He is now best known for his two classic novels, Animal Farm and Nineteen Eighty-Four, although he was also a prolific essayist and contributed to many publications during his writing career. He was especially concerned about the uses and abuses of language, in particular how its gradual disintegration made a direct contribution to poor quality thinking; a central theme in his dystopian novel Nineteen Eighty-Four.

Reference

Confident or Arrogant speakers

2007-08-01T15:44:00.000-05:00

When you listen a talk, you may judge whether the speaker is confident or arrogant, by the use of following ways I introduce:

1- Arrogance is often underplayed by "insecurity". An arrogant speaker tends to be so in order to compensate for weaknesses. However, a confident speaker has self acceptance, accepts the restrictions of the theory or model.

2- An arrogant speaker tends to put others down in an attempt to be the best or come out the coolest model. A confident person is beyond this way of viewing models.

3- Body language of an appearant speaker is often associated with a posture that is overly dominating.

Since arrogance often accompanies a lack of confidence, the poor arrogant speaker hurts underneath.

Slides of my talk

2007-06-23T00:15:00.000-05:00

I have posted today the slides of my recent presentations about the two new properties in loop quantum gravity to my homepage. You can find them in PDF format from here.

John Brodie Prize

2007-06-22T18:27:00.000-05:00

On October 2006 I received a prize for "Creativity and Independence in Research" from perimeter Institute.

Here is the official announcement:

I remember John Brodie from the first year of my coming to PI. He was gentle and open to new faces. I talked to him several times mostly baout art. He was a very kind boy. God bless him.

The works I became nominated for were my recent works on two new properties in loop quantum gravity: 1) the Generic Degeneracy, and 2) the Ladder Symmetry. Based on these two I proposed a macroscopic effect of loop quantum gravity in black hole Hawking's radiation. (1, 2)

Quantum black hole in Loop Quantum Gravity

2007-01-09T14:53:00.000-06:00

Today micro black holes are known (seeing the brief review). However, we do not know what is a quantum black hole?

A quantum black hole is not necessarily a very small black hole. In fact, large black holes may or maynot demonstrate some quantum effects when they touch their outer pace.

In Loop Quantum Gravity, there are two crucial pictures for a quantum black hole.

1- Quantum Isolated Horizon,(aka ABCK model, proposed about 1996-7 by Ashtekar, Baez, Corichi, and Krasnov - major reference).

In this picture, first a spacetime with internal boundary (at the horizon of a black hole) is considered. Then, some conditions are imposed on this boundary in order to make it behave like a black hole horizon from the thermodynamic point of view.

After that, the spacetime is quantized. This is done by promoting the gravitational degrees of freedom (the Ashtekar variables -on holonomies- and their conjugate momenta) to operators. The Hilbert space of such a spacetime is separated into the one of the bulk and the one of the internal boundary.

The Hilbert space associated to the bulk fields contains the spin network states, defined on one dimensional floating graphs embedded into the bulk. The Hilber space of the boundary is simplified by gauge-fixing. The contribution of the boundary in the spacetime action is a Chern-Simons term.

Each bulk edge interesect at the boundary at a puncture. The wave function associated to a puncture is not unique. This is pretty similar to regular quantum mechanics in which when the angular momentum j is projected on the z-axis it takes 2j+1 possible components m, where m=-j, -j+1, ..., j-1, j. In fact, each puncture is a degenerate state. A puncture corresponding the edge of spin j takes 2j+1 degenerate states on the horizon Hilbert space.

On the other hand, each interesecting edge carries the area proportional to the edge spin. An edge of spin j generate the area proportional to [j*(j+1)]^0.5. Thus, associated to the degenerate wave function of a puncture, there is one area. This degeneracy is the root of black hole entropy, this picture says.

These punctures are responcible for the curvature of the horizon and everywhere else on the horizon is flat.

Following picture shows the portrait of a quantum isolated horizon:

A quantum isolated horizon

This model is conceptual restricted and a more fundamental microscopic description should be possible. I can give three reasons for this:

(i) in general relativity metric extends through a black hole via the junction conditions. However in quantum limits, the spin network states must extend through the horizon. A quantum isolated horizon forbid the extention by treating the black hole as the internal boundary of space.
(ii) the horizon in this picture is defined by the classical notion of localization. However, it is completely known that the notion of quantum localization is different than its classical version. Thus a quantum horizon must be localized as a ‘quantum boundary’ of its interior states.
(iii) the bulk edges may only end at the boundary at punctures and no tangential edge is allowed. Why? This is a too strong assumption!

2- Black Hole Spin Network (Proposed recently. Reference)

As a second picture, spacetime is first geometrically quantized, without reference to the horizon. Instead of partial gauge-fixing, a condition that a surface be a horizon of a black hole is imposed on a surface in the full quantum state. The result is that no dynamical constraint is imposed at the horizon. Instead, a black hole horizon is defined by a partition of a spin network.

In this picture all of the above ambiguities are resolved, although the dynamics of this model has not been completed yet. See the papers of Viqar Husain and Oliver Winkler (see 1 and 2), Martin Bojowald (see here), and I (see 1, 2).

The portrait of a Black Hole Spin Network is as the following

A black hole spin network

Two results quickly followed from this picture of black holes.

1- The first is a new computation of black hole entropy on the basis of a degeneracy in the spectrum of areas.

These came from states that were excluded from the isolated horizon boundaryconditions. In fact, their exclusion is a result of imposing a classical notion of black hole horizon as a boundary condition, and then quantizing, rather than quantizing and then identifying a surface as an horizon.
The fact is that the background independent area operator is generically a degenerate operator. The area eigenstates associated to quantum surfaces are not unique! Some of the are eigenstates in the complete spectrum may be associated to one area eigenvalue.

The following graph shows how the degeneracy is correlated

Genericness of area degeneracy in loop quantum gravity (from here)

2- The second payoff of the new definition of a black hole horizon is the prediction of small, but potentially observable corrections to the Hawking’s thermal black hole radiation formula. This happens by considering the fluctuation of horizon area in the kinematical step of the black hole definition. The full spectra of the area operator have an unexpected symmetry that was previously unnoticed. This leads to a physical effect, which is amplification of some modes of black hole radiation. This conclusion differs from Hawking’s original prediction even for massive black holes.

Let me explain this a bit more.

The complete spectrum of area in LQG is such that the gap between different levels of area eigenvalues become smaller in higher levels. But it is proved mathematically this spectrum can be split exactly into evenly spaced subsets. The gap between levels in each one of the subsets is unique and propostional to square roots of all square-free numbers

(Squarefree numbers are those numbers whose prime number ingridients are not repeated. For example 18=2*3*3 is not a square-free number, but 15=3*5 is. These numbers have been studied heavily in Number theory. You can see some of their amazing propeties here.)

Each one of the evenly spaced subsets, to which the complete spectrum of area eigenvalues are splitted, is called a "generation".

Black hole is a sector of spacetime on which horizon area A is proportional to mass squared M^2. Thus, the quantum of energy and the quantum of area are relevant, (1/M) dA = dM. Consequently, the fluctuations of the horizon are seen as the transition of black hole mass, the emission of energy (energy radiation).

Having splitted the complete spectrum of area into different evenly spaced sets of numbers (with different gaps), the area transitions fall into two categories:

Generational Transitions, those transitions occuring between two area levels of the same generations.
Inter-generational Transitions, those transitions occuring between two area levels of different generation.

The frequencies emitted via generational transitions are all proportional to each other by integers and thus are called "harmonics". This is not the case for the intergenerational transitions. The following picture discribes this graphically.

The area transitions as how loop quantum gravity discribes. (from here

In one generation, a harmonic frequency can be generated by transitions from many pairs of levels. For example: the frequency of the emission from te level 3 to 1 can be reproduced by the transitions from level 4 to 2, the levels 5 to 3, etc. This is not the case with the intergenerational frequencies.

Therefore the average number of photons at the harmonic frequancies exceeds the other frequencies. Among the harmonic frequencies themelves, the number of photons corresponding to the transitions from nearby levels are more than others. The reason is simple. The more the gap between levels decreases, the more photons are created at each generational transition.

Therefore, a few of the lines in the radiation spectrum are expected to be the brightest lines. These lines are all unblended. Exact calculation predicts the following spectrum for a black hole radiation:

The spectrum of a black hole radiation as how loop quantum gravity predicts (from here)

Here wo is of the order of 10^16/M(kg) electronVolts, which can be of the order of 10keV for a primordial black hole of mass M=10^12kg.

This makes it possible to test loop quantum gravity with black holes well above Planck scale. These predictions will become amenable to experimental check if primordial black holes are ever found. In fact, this prediction has opened a window upon quantum gravity that does not require reaching down to Planck scale physics.

Cosmic Variance

2005-11-09T06:17:00.000-06:00

Cosmic Variance is a new group weblog that is written time to time by Mark Trodden, Risa Wechsler, Sean Caroll, etc. It is about astrophysics and the newest outcomes of the relevant theories of cosmology. Very interesting job!

Shahriar Afshar's weblog

2005-11-09T03:32:00.000-06:00

Shahriar Afshar is known in physics community by his quantum experiment of single photon. Shahriar has made a weblog and write time to time about his experiment in it. He wanted his readers to ask him their questions and he will be answering them. A good opportunity to learn more about the experiment.

I welcome Shahriar to the community of scientific webloggers.

Buissiness of Citation in Physics Community

2005-11-08T00:15:00.000-06:00

Yes, in today's Physics community there is such a very important buissiness. Yes, the lack of fair scientific view on papers.

"He never references us, so we're not gonna reference him."

A statistical formalism of Causal Dynamical Triangulations

2005-05-18T22:30:00.000-05:00

Recently, I and Fotini Markopoulou rewrote the Causal Dynamical Triangulations model as a spin system and provided a new method of solution of the model. The model was studies before this by Ambjorn (Niels Bohr Institute), Anagnostopoulos (Univ. of Crete) and Loll(Institute for Theoretical Physics, Utrecht University). They invented this path integral approach toward 2d quantum gravity and applied the generating functional method in their solution. (Refrence)

In addition, they have extended the model to higher dimensions (refrence) and coupled it to matter (refrence). It is interesting that a 4 dimensional spacetime is emereged by gluing 4 simplices in a specific way.

Now one can have enough fun with the new approach to the solution of the 2 dimensional model, RG transform its couplings easliy and predict the value of cosmological constant!

These models are based on the notion of the existence of a pre-assumed time in the universe and construction is led into that direction, otherwise the dimensionality of the global spacetime grows fast to infinity.
(The paper - more pictures)

Meeting on non-perturbative background independent Quantum Gravity

2005-05-13T12:39:00.000-05:00

Here is the official webpage of this year's meeting on non-perturbative background independent Quantum Gravity, which takes place from 10-14 October 2005 at the Albert-Einstein-Institute in Potsdam, Germany.

Sean Carroll's lectures

2005-05-11T04:49:00.000-05:00

Sean Carroll, the author of the book of Spacetime and Geometry, is giving a series of lectures in CERN about cosmology for particle physicists. The video of these talks are available a few hours after each in here. More information about this lecture.

Self-organized criticality in quantum gravity

2004-12-28T21:43:00.000-06:00

Recentely I and Lee Smoin studied a simple model of spin network evolution motivated by the hypothesis that the emergence of classical space-time from a discrete microscopic dynamics may be a self-organized critical process. Self organized critical systems are statistical systems that naturally evolve without fine tuning to critical states in which correlation functions are scale invariant. We study several rules for evolution of frozen spin networks in which the spins labelling the edges evolve on a fixed graph. We find evidence for a set of rules which behaves analogously to sand pile models in which a critical state emerges without fine tuning, in which some correlation functions become scale invariant.