Friday, 31 August 2007

Opinion formation in real societies

When I have published the previous post, which was simply prompted by my personal interest in modelling social phenomena using some tools coming from physics, I had absolutely no idea of connecting it to current turmoil in Polish politics.

For those of you from abroad, who (rightly so) are not really interested in Polish power struggle, I owe a brief exposition: the Polish government, since about a month led by minority Law and Justice party is making crazier and crazier decisions. Should you want to look, with imparial eye on the situation, here is the Reuters news bite Polish government critic detained, opposition outraged.
The opposition and human rights groups say the government's anti-corruption drive has turned into a witch-hunt in which anyone who does not share the ruling party's views is branded a criminal or a traitor to Polish interests.

But this blog is not political (although I do have very definite political opinions). So why do I mention the topic? It is because of the statement issued by the Prime Minister to Gazeta Pomorska, in which he reiterates not only his opinions about the existence of `the system' (układ) - setup of criminal activities linking everybody to everybody (excluding only his closest collaborators). This is old story. But the interview confirms that the government conducts a scientific investigation using computer model that shows that the układ is real!

Wow! And I called for developing the model only two days ago! There must be really powerful people reading my blog.

Wednesday, 29 August 2007

Opinion formation in network models of societies

Some years ago I have dabbed for a while in simple simulations of social phenomena. My rather rusty programming skills and some elementary physical mathematics has allowed to produce some models. I got interested in the network models, especially the preferential attachment networks (for details hunt down works of Barabasi, Dorogovtsev, Mendez or Newman, see also bibliography of the In the Country of the Blindfolded).

Since this time I have received a few papers on close subjects to review, which I have done to the best of my ability. I no longer have the time to continue my own studies (they were done during a forced sabbatical between two jobs caused by non-competitiveness clauses in the contract). But looking through the literature on the subject, which seems to grow exponentially (the subject is relatively easy, it is also quite easy to obtain funding - from either physics or soccial sciences departments, and it seems to be one of the fashionable ones), I do see a less trodden path.

Perhaps someone would like to take it?

The idea is based on the reversal of the preferential attachment (`the rich get richer') phenomenon that seems to be found in many networks (from the physical Internet infrastructure, throuth WEB, to scientific collaborations and actor's relationships). In processes that govern the formation of opinions in modern societies, such networks, with influential hubs play an important role. While many early models were based on 1D or 2D close proximity opinion exchanges, in today's small world we interact via networks.

But one phenomenon that is quite crucial for the models dealing with information spread and opinion formation in such networks is that people quite readily cut the links with those who are `not to their liking'. Thus, instead of getting converted to majority opinions, the enclaves of like minded people are formed, cut off from the main network. We all see it in real life, especially in dramatic circumstances of terrorist gropups and their supporters.

Computer modelling would help in establishing the conditions that would diminish this tendency to cut off the links with those who do not share our opinions. Some incentives for keeping the links open (for example through promoting participation in `open' activities and societies, where ideas are exchanged) might be included in the models and studied.

One of my friends has remarked that such computer models in themselves are worthless, as they are purely artificial. Without reference to real life data (experimental or observational) the models are just toys. I agree. But the phenomenon of cutting the links is easy enough to study in reality. One can imagine, for example, monitoring the evolution of links between students on a campus of a University, as they go throught the period of study and later disperse to their jobs. Smaller groups could be used to monitor susceptibility of connections to differences in opinions. So, it does not have to be a purely artificial topic.

Question: does anyone know of works already done along these lines?

Monday, 27 August 2007

Quantum Mechanics again

QM seems to have a practically unfathomable reservoir of surprises. A recent work on Progressive field-state collapse and quantum non-demolition photon counting by Christine Guerlin, Julien Bernu, Samuel Deléglise, Clément Sayrin, Sébastien Gleyzes, Stefan Kuhr, Michel Brune, Jean-Michel Raimond & Serge Haroche, published in Nature 448, 889-893 (23 August 2007) has caught my attention.

The experiment is designed to observe, with as little disturbence as possible, the quantum state of a cavity containing an initially unknown number of photons. The authors describe it as follows:

The irreversible evolution of a microscopic system under measurement is a central feature of quantum theory. From an initial state generally exhibiting quantum uncertainty in the measured observable, the system is projected into a state in which this observable becomes precisely known. Its value is random, with a probability determined by the initial system's state. The evolution induced by measurement (known as 'state collapse') can be progressive, accumulating the effects of elementary state changes. Here we report the observation of such a step-by-step collapse by measuring non-destructively the photon number of a field stored in a cavity. Atoms behaving as microscopic clocks cross the cavity successively. By measuring the light-induced alterations of the clock rate, information is progressively extracted, until the initially uncertain photon number converges to an integer. The suppression of the photon number spread is demonstrated by correlations between repeated measurements. The procedure illustrates all the postulates of quantum measurement (state collapse, statistical results and repeatability) and should facilitate studies of non-classical fields trapped in cavities.

I must admit that my understanding of QM gets more and more inadequate with every such report. For example I do not understand how the `non-destructive' measurements, proposed by the authors really influence the state of the photons. Perhaps they do not change their number.

In this experiment, light is an object of investigation repeatedly interrogated by atoms. Its evolution under continuous non-destructive monitoring is directly accessible to measurement, making real the stochastic trajectories of quantum field Monte Carlo simulations

What is observed is the collapse of the state into one with a defined number of photons. Then the observed number remains constant - until the cavity absorbs one of the photons (on a much larger timescale) and then the measurements show this smaller number.

When I find the words `repeated interrogation' my mind jumps to `continuous measurement' and thus to the Quantum Zeno Effect. Is there any connection?

And one more remark: the short article on the discovery on has attracted a few comments. By far the most extensive is one by Andrei P. Kirilyuk, who is a champion of "Universal Concept of Complexity by the Dynamic Redundance Paradigm: Causal Randomness, Complete Wave Mechanics, and the Ultimate Unification of Knowledge"

OK, OK - I admit I do not iunderstand him neither. But there are some tell-tale signs of going beyond normal science. Such as mentioning by Kirilyuk that ALL famous science creators, from Descartes and Newton to Einstein and de Broglie were notorious mavericks understood by almost nobody at the time of their discoveries. Which supposedly builds up his credentials. This reminds me of a famous quote:
They laughed at Copernicus.
They laughed at the Wright Brothers.
Yes, well, they also laughed at the Marx Brothers.
Being laughed at does not mean you are right.

Another signal is that Citebase lists 18 articles quoting the Kirilyuk work ... all of them by ... Kirilyuk himself.

Concluding: it is difficult to follow the new developments in physics. A lot depends on the peer review. But - should we have some sort of mechanism for the strange approaches that are out of the mainstream science? Would the famous EPR paper be published today? Especially if the author list did not include Einstein?

Monday, 20 August 2007

Marvel (at the) Universe

That physicists are a curious crowd I knew since my own science days. But that government officials are willing to pay them for the fun they have is sometimes, astonishing.

Consider the recent paper by P. M. Gleiser, How to become a superhero.
It is devoted to analysis of
collaboration network based on theMarvel Universe comic books. First, we consider the system as a binary network, where two characters are connected if they appear in the same publication. The analysis of degree correlations reveals that, in contrast to most real social networks, the Marvel Universe presents a disassortative mixing on the degree. Then, we use a weight measure to study the system as a weighted network. This allows us to find and characterize well defined communities. Through the analysis of the community structure and the clustering as a function of the degree we show that the network presents a hierarchical structure. Finally, we comment on possible mechanisms responsible for the particular motifs observed.

Hmm. Looking at the results we find all the typical traits of complex networks: power law distributions, hubs, giant components. Funny. Even funnier is the acknowledgements part of the paper:
This work has been supported by grants from CONICET PIP05-5114 (Argentina), ANPCyT PICT03-13893 (Argentina) and ICTP NET-61 (Italy).

It makes me wish to come back to physics. At least in Argentina or Italy...

Sunday, 19 August 2007

Divination solved?

Wandering through one of the largest Polish Internet bookshops I have found, in the physics section couple of books on divination, pendulums and rods. Well, I know that there are publishing houses that would publish anything, but my habit of checking the sources and trying to find the roots kicked in. I had no intention of making the authors richer (there are enough people for this) I searched the WEB for the original works. And, indeed I did find some. For example I have found a publication in a Polish language Fizyka i Przyroda (Physics and Nature), by Piotr Tyrawa, titled "How I solved the rod and pendulum phenomena"

Wow! There is thus ONE person in the world who has solved the phenomenon! I went through the paper (in Polish, unfortunately) and it is as far from a solution as possible.

You might say - just another crank, just another esoteric WEB site and publication. But it is not so: the Fizyka i Przyroda is sponsored by the Polish Academy of Sciences Institute of Physics and Institute of Nuclear Studies. It promotes physics competitions. The publications include some very good - though elementary - texts, such as a study of radioactive properties of granite by a high school student. Hardly surprising - but solid piece of intrioductory experimental work.

And I wonder how would the two Institutes feel to be associated with absurd divination studies.

Thursday, 16 August 2007

Classical physics is fun

Should anyone think that only the quantum boundaries of physics are interesting, here is an example: The Existence of Noncollision Singularities in Newtonian Systems by Zhihong Xia
The Annals of Mathematics, 2nd Ser., Vol. 135, No. 3 (May, 1992), pp. 411-468.

Unfortunately, I know this article only by reflected light, I have not been able to find a freely accessible version. But the ripples and comments it has made are quite numerous, for example Noncollision Singularities: Do Four Bodies Suffice? by Joseph L. Gerver, or EJECTIONS AND CAPTURES BY SOLAR SYSTEMS

What is the point: simple that there is a possibility to cleverly construct a classical (Newtonian) system of five bodies that would result in expulsing one of them to infinity in finite time.

Just pure fun? Not really - it turns out that such result has implicationsas to physical computability, Church-Turing hypothesis, the whole issue of determinism in classical physics. If a body can be expulsed to infinity that by simple time reversal and initial conditions reversal a body can appear in the system and become a part of it, in finite time from infinity! And this means that there might be an essentially unknown and unknowable influence (unknowable because it is infinitely removed) that would act on the system - again, not infinitely far in the future but in finite time.

The paper is quite old (15 years) but compared to the age of Newtonian theory it simply shows that an old dog still has a lot of tricks to learn.

Wednesday, 8 August 2007

Light faster than light

Browsing through arXiv repository of preprints I have found a short paper Macroscopic violation of special relativity by
Authors: G. Nimtz, A. A. Stahlhofen.

At first I was surprised by the bold statements of the authors:
We demonstrate the quantum mechanical behavior of evanescent modes with digital microwave signals at a macroscopic scale of the order of a meter and show that evanescent modes are well described by virtual photons as predicted by former QED calculations.

Several QED and QM calculations predicted that both evanescent modes and tunneling particles appear to propagate in zero time.

All three properties - the violation of the Einstein energy relation, the zero time spreading, and the non observability of evanescent modes - can be explained by identifying evanescent modes with virtual photons as predicted by several authors, see for instance references. Tunneling and evanescent modes are properly described by quantum mechanics

The (unpublished) paper's form is `unacademic' (i.e. not TeX-ed...) and at first I had doubts as to the credentials of the experiment. Was it another out-of-nowhere Einstein basher? But further search has showed that this is a paper from a long series of publications involving light and microwave signal processing in unusual setups. For references it suffices to search arXiv for au:Nimtz_G

Signaling faster than light speed? Not only possible but observed?
In the light of a recent discussion with a friend (also on this blog...) how would one describe it in a quantum way? or photons as billiard balls way?

Saturday, 4 August 2007

Islam and physics

In a recent issue of Physics World I found a very interesting interview with an Iranian Physicist, Reza Mansouri.
It provides a very clear explanation of the problems that deeply religious society and religious government pose for science education. According to Mansouri `there is little research activity in most areas of physics, and indeed science as a whole, in Iran'. There are maybe 500 PhD educated physicists, and we can only guess how many of them work on the state nuclear programme. Who really believes Iran needs atomic reactor for peacefil energy purposes?. The problem, says Mansouri, is
that Iran, like other Muslim countries, has a very distorted view of what science is – a problem that is rooted in culture and reflected in language. He points out that the Arabic term elm (which is used in almost all Muslim countries) is often taken to mean `science', but this word in fact refers to a deep knowledge of Islam. Indeed ahl e elm means `religious scholar'. Consequently, there is no clear distinction between the meaning and purpose of science and the meaning and purpose of theology.

Iranian universities today do teach science beyond that required for practicing Islam, but Mansouri believes that the legacy of this narrow mindset means that students still learn a very prescribed curriculum by rote, rather than being encouraged to investigate subjects for themselves. [...]

This view of science as a fixed body of knowledge then shapes the way politicians think of science and therefore how they fund it, he says. They view a scientist as an ahl e elm sitting in a small study who will at most need money for new books rather than the far greater resources needed for experiments, lab technicians and computers. The result is that Iran spends only about 0.5% of its gross domestic product on R&D.

It is quite interesting to note that in Poland the R&D spending is about 0.59%, very, very close to Iran. Is there a sign of some deeper similarity? (This compares to USA with 2.76%, Japan with 3.12% or European Union average of 1.93% (data for 2002)).