Saturday, 26 January 2008

Strings, LQG and all that

During a week long business trip I have finished reading a book by Peter Woit, Not Even Wrong, about the failure of the String Theory. I have then augmented it by several articles by Carlo Rovelli (especially Notes for a brief history of quantum gravity, and A dialog on quantum gravity, Int. J. Mod. Phys., 2003, D12, 1509-1528). Just to preserve the balance I leafed through Brian Greene books and Leonard Susskind Cosmic Landscape.

Results? Of course I do not understand String Theory not Loop Quantum Gravity. But as for human side, it is quite interesting.

The situation seems more than lightly skewed. While Woit and Rovelli discuss at length the pros and cons of string theory and its alternatives, the proponents of string theory behave somewhat differently. For example, Susskind devotes a single paragraph (about six lines of text) to Loop Quantum Gravity,
stating that it `is an interesting proposal, but it is not nearly as well developed as String Theory'. He continues:
As much as I would very much like to balance things by explaining the opposing side, I simply can't find that other side.

Very similar stance is taken by Greene in The Elegant Universe. He devotes about four pages to `criticisms of String Theory', which he starts as follows:
Is string theory right? We don't know. If you share the belief that the laws of physics should not be fragmented into those that govern the large and those that govern the small, and if you believe that we should not rest until we have a theory whose range of applicability is limitless, string theory is the only game in town.
You might well argue, though, that this highlights only physicists' lack of imagination rather than some fundamental uniqueness of string theory. Perhaps. You might further argue that, like the man searching for his lost keys under a street light, physicists are huddled around string theory merely because vagaries of scientific history have shed one random ray of light in this direction.

But, as Greene argues, these arguments are less and less important as the theory climbs up the mountain of understanding. The fact that it does not have any connection with experiment and reality is, for Greene, but a temporary matter, a `historical asynchrony'. What he hopes is that soon experiment would be able to confirm the results. The book has been written before the number of solutions of String Theory grew so much that any solution became possible, somewhere within the immense landscape which made the falsification near impossible. But the departure from the classical ideal of falsifiability by experiment is not critical for many proponents. The beauty of String Theory with its self-consistent finite number of dimensions, slightly spoiled that the number is wrong, not four but ten or eleven, and deep mathematical relationships is for many enough to continue the work. Both books by Greene and Susskind (as well as the one by Woit) are of the popular science genre. Thus, they may be considered as examples of what the scientists want to communicate to the lay public. And in the proponents of the String Theory it is clearly the excitement of research but also a lot of Public Relations. Look, we are climbing the mountain! We're just below the summit! The critics voices, more sombre, point out the less optimistic perspective. Is this good PR? Should we, scientists, show the public that we might be spending their money without getting results? Should we admit that some efforts (and funds) are wasted on wrong theories and failed experiments? If one looks through most of the books on history of science we usually see an uninterrupted march of progress, leaping, from tree to tree, like the Monthy Pythons lumberjack. Yes, there are some pet `wrong theories', like the phlogiston, or Ptolemaic system to show that progress is sometimes at expense of old ideas. But finding the day-to-day struggle with failed concepts, with ideas that caught fire for a couple of years only to be forgotten after a decade, is much more difficult. And for anyone who does dig deeply enough into the history of science, it is soon clear that this waste of funds and effort is an indispensable part of the success of science. Discovery can be achieved only by going into unknown. And this, by definition, means traveling without paths, often in a wrong direction.

The String Theory controversy, even taking into account its relatively low profile and the disproportions in the numbers of critics and supporters, is one of the crucial disputes in modern science. First, because it touches issues of group behaviour, career development, freedom of research. The question is: how can we expect to boost creativity if all the money (from limited and shrinking funds) is directed into one approach? What is the result of all the young, enthusiastic physicists flocking into one path?

The second issue is the role of Public Relations in science. In which way should the work be portrayed, is is allowed to publicize the controversies and questions? At first glance the situation in String Theory looks like a perfect case study for the radical `science studies' proponents, the deconstructivists and others. There is a lot of political agenda visible, a lot of social and psychological motives. But then the question becomes: can we separate the human and political aspects from the scientific content of the debate? Ultimately, some of the equations, some of the experiments would show who was right and who was not. This is at least what most of the physicists on both sides of the dispute hope for. How, then, could a sociologist decide who is right today, without understanding the physical problems? I am quite sure that most of the hard words expressed by the participants of the debate result not from some character flaws or political agendas but from deep convictions about the nature of the Universe. Yet, on the other hand, the social phenomena, such as tenure track selection or funding decisions are real.

The third issue is more physical: can we expect that any of the theories would touch with any experiments or observations in a foreseeable future? It seems that a small (but very fundamental) part of physics has turned into speculative metaphysics, where theories are laced so far ahead of experiment, that decisive factors are mathematical beauty or popularity. Some people might think that these are sufficient motivations for support. Some disagree.
But whatever our human inclinations are, the real verdict is still out --- there is no Quantum Gravity today.

Sunday, 13 January 2008

A scan(ny) for your thoughts, my dear

I got interested in a recent news reported by Science Daily. Apparently a group of researchers from Carnegie Mellon University has been able to
identify where people's thoughts and perceptions of familiar objects originate in the brain by identifying the patterns of brain activity associated with the objects.

A dozen study participants enveloped in an MRI scanner were shown line drawings of 10 different objects -- five tools and five dwellings --one at a time and asked to think about their properties. Just and Mitchell's method was able to accurately determine which of the 10 drawings a participant was viewing based on their characteristic whole-brain neural activation patterns. To make the task more challenging for themselves, the researchers excluded information in the brain's visual cortex, where raw visual information is available, and focused more on the "thinking" parts of the brain.

I'll need to have a deeper look at the original work, because the news reporting is, perhaps, a bit on the hype side, but nevertheless, this sounds like Science Fiction, doesn't it?

Thursday, 10 January 2008

Judging by appearances - String Theory

In the recent issue of the New Scientist (january 5th, 2008) I have found an article on an new development in string theory, String theory may predict our universe after all, by Anil Ananthaswamy. The news is that instead of the `traditional' string theory landscape of Universes, with maybe 10^500 possible universes, differentiated by 10 dimensional manifolds, there may be a way to arrive at our Universe, via some kind of path through the landscape. An evolution through the landscape if you will.
The idea is quite interesting, it offers a new way of explaining our own Universe, other than anthropic principle of pure luck. So I read the article, and also adhered to my usual advice: I followed the sources, in this case a paper by Philip Candelas, Xenia de la Ossa, Yang-Hui He, Balazs Szendroi, titled Triadophilia: A Special Corner in the Landscape. I looked at both and come out with quite a lot of observations.

However, before I present them, a word of warning: I do not have any special knowledge of string theory beyond the popular books and papers. I would not recognize a string-theoretic equation. I have met most of the terms used in the discussion below for the first time. I am a perfect amateur here.
But - does it make me totally unqualified to judge the matter by appearances? I let you decide...


My problems started with the following paragraph in the New Scientist article, describing what Candelas and coworkers did:
The group placed all of the known Calabi-Yau manifolds on a diagram, plotting their topological complexity - for instance, how twisted and contorted the manifold is - against their "Euler number", which mathematicians use to dictate how the extra dimensions can be compacted.

The plot turned out to have the shape of a cone (see Diagram).

When I turned to the original paper I found a diagram that was similar, yet significantly different.

It is not the question of colour. It is, for example, how the axes are labelled. In case of New Scientist the vertical axis is a mysterious `complexity of manifolds'. In the original paper it is also rather mysterious quantity h^11+h^21. But knowing this makes the mysterious cone shape very simple of origin: The oblique axes bound the region where h^11 and h^21 are greater than zero.

The next problem is the visual suggestion that all interesting things happen at the bottom triangle, strengthened by the arrow in NS picture. Well, this is what the authors argue, that's true. But we should be really cautious to let us be guided away from the top of the triangle. The facts that points representing manifolds are getting sparser as one moves up is not a property of string theory (I think) but rather reflects our limited knowledge of the manifolds. as Candelas et al. write, the diagram represents only manifolds from Kreuzer-Skarke list. There are no informations on all the 10^500 (?) manifolds allowed by String Theory.

The question becomes: can such editing of the original research, undoubtedly aimed at improving understanding and making `the story' more colourful, be considered fair? Does the triangular shape comes from simple mathematical condition and not from profound discovery? Or am I oversensitive, and all journalist media, including blogs (such as mine) have to exaggerate...

Monday, 7 January 2008

Global warming again

recent days in Poland were rather cold (-10C) with wind chilling us to the bone. In such a weather it is quite strange to think about global warming, but still...

I have found recently the following paper:
Douglass, D. H.; Christy, J. R.; Pearsona, B. D. & Singer, S. F.
A comparison of tropical temperature trends with model predictions International Journal of Climatology, 2007.

The article compares several General Circulation Models (GCMs) with observations. And, not surprisingly for a topic of my blog, it finds some discrepancies.

In the summary of the article, the authors state
We have tested the proposition that greenhouse model
simulations and trend observations can be reconciled. Our
conclusion is that the present evidence, with the application
of a robust statistical test, supports rejection of this
proposition. [...] On the whole, the evidence indicates that
model trends in the troposphere are very likely inconsistent
with observations that indicate that, since 1979, there
is no significant long-term amplification factor relative to
the surface. If these results continue to be supported, then
future projections of temperature change, as depicted in
the present suite of climate models, are likely too high.

Now I do not have the time nor the knowledge to follow my usual advice and to go for the sources. But the paper, with its controversial claims, has been published in a peer-reviewed journal of the Royal Meteorological Society. Presumably these people know what they write about. Or can anyone tell me that they are wrong?

The World Climate Report blog
discusses the paper and and the opening comments are quite important. I think anyone who wants to discuss the Global Warming should remember that the scientific research on the matter is far from over, and that giving politically motivated Nobel Prizes does not settle the discrepancies between observations and predictions.
Over and over, we hear that the global warming debate is over, the science is settled, and it is time to move past the science and turn the focus onto the policy side of the issue. Anyone who suggests that the science is not settled and the debate is still alive is immediately accused of being heavily funded by industry and discredited by the mainstream scientific community. Who could forget the August 13, 2007 Newsweek issue with its cover suggesting “naysayers” are well-funded by industry and apparently unaware that the Earth is becoming the red planet.

Anyone who reads World Climate Report regularly is aware that the debate is very much alive and well in the major scientific journals related to global warming. We find numerous articles each year presenting results that are clearly at odds with the popular predictions and claims of the global warming advocates.

By the way, I am not funded by the industry in writing this blog. Anyone willing to change that?

Sunday, 6 January 2008

Evolution wars continue

Recent publication of a booklet promoting evolutionary biology by the National Academy of Sciences in US, downloadable from here, has led me to a response from the chief institution promoting the so called `Intelligent Design' theories, the Discovery Institute (found here).

Dear Educator:
This briefing packet was developed in order to provide you with
clear and accurate information about the scientific theory of
intelligent design: what it is, how it originated, and how it differs
from Neo-Darwinism. [...]

This presentation which is aimed at US educators who would wish to teach ID contains nothing new (at least for me) in terms of science. But it does contain a very interesting assertions regarding education:
Discovery Institute opposed the Dover policy from
the start and urged the Dover school board to repeal
it. [...]

As a matter of public policy, Discovery Institute opposes
any effort to mandate or require the teaching the theory
of intelligent design by school districts or state boards of

Why? Because:
Attempts to mandate
teaching about intelligent design only politicize the theory
and will hinder fair and open discussion of the merits of the
theory among scholars and within the scientific community.

Now, this is very politically correct language. In fact the presentation reeks with pro-science wording, long reference links list, all four peer-reviewed papers to support ID, and all in all it is as academic and pro-educational as one can imagine. Discovery Institute advocates teaching evolution. (Stressing, of course, the shortcomings of it).

Fine with me. If the children are really taught evolution properly, whether in the US or in Poland, with enough detail to understand the nature of the `weaknesses' singled out by the ID proponents, I would be happy. I have already written in the "CoB" that I would be happy with the children going thoroughly through the challenged curriculum of the Dover district. The problem is, that the criticism can not be addressed without detailed knowledge of other disciplines than biology. For example detailed understanding of geology (to understand the fossil record). Or understanding the basics of information theory, to understand the cornerstone of ID: the irreducibly complex information (ICI).

Try as I did I could not understand the ICI concept myself. And I went through quite a lot of available sources. It sounded like a repeated incantation to me. So, maybe there is someone who can explain it to me?