Friday, 26 May 2006

Evergrow Workshop

I'm going to Israel in two weeks to attend The EverLab Cluster and Numerical Experimentation in the Virtual Observatory - Evergrow SP2 Workshop in Jerusalem. It will be a workshop to learn how to use a network of clusters of computers that will connect machines in different european countries which are members of the project Evergrow. The idea is that if you need powerful computational resources to run some program, you can distribute the job between all these machines and reduce the computation time.

Evergrow project is an european community project spread around universities in the whole continent. The aim of the project is to study the mathematics and physics of networks with an eye in practical applications in the Internet. There are different modules of the project divided between each member country and here in the NCRG I'm a research fellow of this project.

As I'm going to Israel, I've just put a little map of the countries I visited in the sidebar at your left. :) Okay, it has just two countries till the moment, but I hope that it will change in the next future. At least, it will have Israel when I come back from the workshop.

There is also one interesting news I found today about invisibility cloaking: Physicists draw up plans for real 'cloaking device'. I have already seen a jacket made of optical fibers once that would render you almost invisible (if someone could remember the link and tell it to me, I would be glad). The idea of invisibility is to find a way to let an incoming light ray contour your body in such a way that it proceeds from the other side in a path that is the exact continuation of the path that was being traced by the incoming ray. The fiber jacket works just aproximately because you have some distortion as it is very difficult to make the outgoing ray follow the path that is the exact match of the incoming ray. But I believe that this difficulties will be down some day.

On my desk:

Picture: logo of the Evergrow Project taken from its website.

Wednesday, 24 May 2006


Reactor, by Carl Goodman

I have nothing too specific to put here today, but I found some things in the web these days that I think it would be interesting to share:

HTML Book from John Baez
John Baez is a well-known mathematical-physicist that usually works with Quantum Gravity (most of the time with Spin Networks I guess) and writes a lot of interesting stuff. Particularly interesting is his book Gauge Fields, Knots, and Gravity which has a lot of introductory math and physics. Well, let us come back to the main point. The text I found interesting from him is Higher-Dimensional Algebra and Planck-Scale Physics and here is the abstract:

This is a nontechnical introduction to recent work on quantum gravity using ideas from higher-dimensional algebra. We argue that reconciling general relativity with the Standard Model requires a `background-free quantum theory with local degrees of freedom propagating causally'. We describe the insights provided by work on topological quantum field theories such as quantum gravity in 3-dimensional spacetime. These are background-free quantum theories lacking local degrees of freedom, so they only display some of the features we seek. However, they suggest a deep link between the concepts of `space' and `state', and similarly those of `spacetime' and `process', which we argue is to be expected in any background-free quantum theory. We sketch how higher-dimensional algebra provides the mathematical tools to make this link precise. Finally, we comment on attempts to formulate a theory of quantum gravity in 4-dimensional spacetime using `spin networks' and `spin foams'.

I also found this site from a guy named Eric S. Raymond. I came to his homepage clicking in the glider (from the Game of Life) image that I'm reproducing here:

hacker emblem

and following the Eric's Home link. You will find that hackers are not exactly those evil programmers you see in movies, which are really crackers. About this, he wrote an interesting page named How to become a hacker.

There is also this news about Gravitational Lensing:
Galactic lens reveals its inner self

This Quantum Poem that I found in the same page where I took the picture in the beginning of the post:

Quantum Physics: There's a Thing
by Graham Adair

Quantum physics. There’s a thing.
I’ve heard of nothing stranger.
You fancy juggling atoms? Well
Be mindful of the danger.
For thoughts of protons, quarks and muons:
Such exotic matter,
Are apt to tie your brain in knots,
Your sleepful nights to shatter.

The Big Bang. Sheesh! Well strike a light!
Is that what really happened?
You’re telling me we all began
As matter crushed and flattened?
And then some great explosion
Thrust us all forth into being?
I think The Big Baloney’s
A better name for what we’re seeing.

Black Holes -- what? You’re kidding me!
A huge contrivance, surely.
A ruse by Stephen Hawking
(Who accepts his praise demurely.)
So if it’s true that black holes
Suck and swallow up all matter,
Why don’t they eat up physicists
And all their nonsense patter?

And what of blessed Einstein
And his General Relativity?
Accepted though it may be
It’s a triumph of complicity.
You test it by experiment,
And analyse the outcome.
And if it makes no sense
You just amend the main theorem!

Herr Heisenberg is in a quandary,
Can’t make up his mind.
He’s dreaming up a Principle,
But unsure what he’ll find.
He thinks the laws of physics
Pose a crisis he’s averting,
But ‘til his theory’s testable
We’ll all remain Uncertain.

Well hip-hooray for SuperStrings!
A unifying theory!
At last we have a model
That’ll settle every query.
But hang on -- it’s just wacky concepts
Fraught with terminology…
It makes no sense; it’s full of holes,
It’s rubbish!
All apologies.

Now here’s a laugh: you take a clock,
And send it into space.
When down it comes, you check the time.
And Lo! It’s lost its pace.
It seems that hours pass slower
As you near the speed of light.
Time-travel’s a reality! And pigs are airborne.

There’s dark misgivings on the rise:
Dark Energy, Dark Matter.
A new theory for why
The Universe is getting fatter.
But is it really growing?
Maybe we ourselves are shrinking!
Collapsing to a speck
Beneath the weight of quantum thinking!

A Cyclic Universe
Is what they’re telling us we live in.
A Big Bang first, expand, contract;
Then Big Crunch, new beginning.
The contents of the universe
Are bound for all eternity
To grow and live, then shrink and die,
Repeating to infinity.

In which case, all the laws of physics
Won’t be here for long.
Like us, they’ll bend and buckle
When the Big Crunch comes along.
The point of Singularity
Will deconstruct all logic,
Our physics theories then will seem
Less real than Discworld magic!

In closing, here’s an observation
Likely to confuse.
The Uncertainty Principle
Declares surprising news:
“To take a thing and look at it
Will change its very state.”
So don’t read my opinions, lest you change them.
Oops. Too late

And finally, you noted that I added a column named "I support" at the side of this blog. It would be worth to click in those links, they're interesting movements that maybe you should consider support too and put a link in your site. :)

Picture: Reactor, by Carl Goodman.

Thursday, 18 May 2006


Some 'digital books' I found these days:

A news about the ending of the sequencing of the human genome:
Last chromosome in human genome sequenced

And finally:

On my desk:

  • Do Black Holes Destroy Information?, John Preskill (hep-th/9209058)

  • Quantum Mechanics of Black Holes, Steven B. Giddings (hep-th/9412138)

  • Quantum information in loop quantum gravity, Daniel R. Terno (gr-qc/0512072)

  • Survey propagation for the cascading Sourlas code, Jonathan PL Hatchett, Yoshiyuki Kabashima (cond-mat/0604267)

Picture taken from: Ecliptic Illustration & Multimedia

Tuesday, 16 May 2006

Fear & Shame


No science today. I'm not in the mood. I'm in UK now, but my family is still in Sao Paulo, Brazil. By now, everyone in the world should know what happened and still is happening in the city. For those who don't, news in four languages:

Sao Paulo, the second largest city in the world, the largest and richest city in Brazil, the industrial and financial centre, is in war. As the news above show, the bosses of organized crime are so powerful in Brazil that they could organize a war operation inside the jail. When I lived in Sao Paulo I was anxious to leave the city because of the violence. This apparent "new" state of civil war is something that citizens of Sao Paulo suffer, in a smaller scale, everyday. Even me, someone who has very little knowledge of politics and social sciences, could see that the situation would reach this chaos someday. And it happened. The sad thing is that, although I'm safe here in UK (or as safe as I can be...), I'm worried with my parents and my relatives.

Brazilian mentality is a stupid one! Brazil has plans of being a "first world country" but wants to do that without any organization, without investing in education and research and without putting an end to the widespread corruption and impunity. In summary: they want to be a great country without any effort.

My wife looked at me with fear yesterday when I told her about the events in Sao Paulo as her family is there too. She said to me: "I don't want to come back". And I had to agree: "Me neither." It's a shame. It's sad, because all my friends and family are there. People who I love and miss. All my memories and belongings are still there. Last week I was thinking that maybe Sao Paulo was not that bad city as I used to think when I was there, but this week I realized that it is simply worst than that.

Now, every brazilian knows what will happen. The politicians of the federal government will use the events to attack the politicians of the oppositians who held the Sao Paulo government as this year is the presidential elections. Very few measures will be taken. They will enhance the vigilance by police (from whom the attacks shown that the criminals have no fear...) for a while until people forget and life goes on, as it always happen in Brazil. Nothing will get better, people simply will get used.

I have friends that say to me: "Situation in Brazil is getting better. The country will be better." I use to say: "Yes, but I'm almost sure that it will not happen in my lifespam". I'm upset, I'm ashamed, I'm said and I'm scared. Unhappily, nothing will change.

Picture: the cap of a cop with bullet holes and his and his friends blood on the floor. Source: Folha de Sao Paulo

Just an update. I've just read that the attacks in SP decreased because THE GOVERNMENT NEGOCIATED WITH THE CRIMINAL LEADERS AND REACHED A CONSENSUS. If this is true, this means that the criminals got what they wanted. It would just show how the government in Brazil is weak and, as I said, things never change there... The government negates the pact. It may be true and this can be a false information, but in Brazil you never know. I hope that I'm wrong.

Friday, 12 May 2006

Pasta Bang

Sometimes you give reasonable arguments about some subject. Sometimes all the scientific community gets involved and give more than reasonable arguments about a subject. But even then, there are people that completely ignore the rational discussion and simply stick to absurd positions for a lot of reasons: proud, fanatism and, sometimes, votes.

Well, when reason fails and the situation becomes so bad sometimes the only thing you can do is to laugh and try to show how absurd the situation is appealing to people's sense of humor. That's what this guys do. Actually, they are trying to show that creationism and intelligent design are just a way of spreading an absurd belief using beautiful words. When you change just the words without changing the core idea (this is fundamental) you can really see what the idea is.

The 'Church of the Flying Spaghetti Monster' is obviously a joke reacting against the teaching of religion masked as science in some schools in the USA, but if you read through carefully, you will see that the arguments they use are exactly the same which are used by creationism and intelligent design. The 'adepts' of the church 'believe' that the universe was created (and is still ruled) by a huge omnipotent pasta god! And they give a lot of evidence in their favor! And talking about evidence, there is even a graphic showing how the global warming is related to the decreasing of pirates in the world as an example that correlation has nothing to do with cause and effect, something well-known in statistics but that most of people forget.

Well, changing subject, I found this interesting news today:
Light's Most Exotic Trick Yet: So Fast it Goes ... Backwards?

Monday, 8 May 2006

QFT: New Online Book

Event from CDF Detector at Fermilab

Professor Jorge de Lyra, of University of Sao Paulo (USP) has just made avaiable online a draft of his book on Lattice Quantum Field Theory. Professor de Lyra works with Lattice Field Theory and in addition is responsible for the group taking care of the Physics Institute network of computers in USP.

I didn't read the book yet and I'll probably will not have the time to do so now, but I encourage anyone to comment on it.

Picture: Event from CDF Detector at Fermilab - taken from David Tong: Research

Friday, 5 May 2006


It has been a long time since my last post. The reason is that I was making arrangements for moving to UK to work in the Neural Computation Research Group in Aston University, Birmingham. Well, I'm in Aston now. But after my arriving I had to solve a lot of problems. The most bizarre one was that I needed to open a bank account to receive my salary, but to open a bank account in UK you need a permanent address. When I arrived here, I was living in a hotel, therefore I didn't have a permanent address. I started to look for a flat to rent, but to my surprise the agencies asked me for a bank account number in order to rent a flat! I could not rent because I didn't have a bank account and I could not open a bank account because I didn't have a permanent address!

The circle was broken by a kind landlord who agreed in renting his flat even without a bank account. So, I could rent the flat, open the bank account and receive my salary. Everything is fine now (at least at the moment...) and I've already started to work.

I'm working here with Statistical Mechanical (SM) approaches to Information Theory (IT). What does it mean? Well, IT is an important area because it deals with exchange and storing of information, coding and decoding and everything else you can imagine you can do with information. There is even a feeling that some fundamental laws of the universe are based on informational concepts. IT was born with french engineer Claude Shannon, although I think I've already said this a lot of time in other posts. Shannon proved a lot of theorems finding bounds to some important quantities like how many information you can transmit when you have noise. This means that the results always are related to worst case situations.

However, sometimes you just want to know what is typical, not the worst case. Let me give an example. Let us say you need to save money to buy a car and you want to know how much money you need to save. Well, the worst case would be a Ferrari or a Porsche, but it will not help cause you (at least most of us) will not be able to save that amount. What you need to know is how much a car 'typically' costs, so you can have an idea of how much you have to save even without choosing the car in advance.

It turns out that SM has the appropriate techniques to do that. The most important one is a technical matter that I'll explain someday named 'Replica Theory'. How is it used in IT? Well, IT deals with transmitting information. We can choose do that bit by bit. We can encode, decode, compress and do a lot of things with information, bit by bit. In practical issues, we deal with a lot of information, that's why your HD has more than 80G today. When we do calculations, this amount of bits can be very well approximated by saying that we have an infinite number of bits. Now we arrived at the point: SM calculations always use the so-called 'thermodynamical limit' (TL), or the limit of an infinite number of components in the system. So, treating each bit as a component of the system formally, we can use SM to analyze what happens in the limit of infinite information! The results obtained can give typical behaviours that approximate very well the cases of practical interest!

Now, I need to come back and study broadcast, multiple access and relay network channels. I'll take some time to talk about them someday, when I learn them better...

On my desk:

  • Remarks on gravity, entropy, and information, Robert Carroll (physics/0602036)

  • Unknown Quantum States and Operations, a Bayesian View, Christopher A. Fuchs, Ruediger Schack (quant-ph/0404156)

  • Why can states and measurement outcomes be represented as vectors?, Piero G. L. Mana (quant-ph/0305117)

  • Quantum Theory From Five Reasonable Axioms, Lucien Hardy (quant-ph/0101012)

  • The Born Rule in Quantum and Classical Mechanics, Paul Brumer, Jiangbin Gong (quant-ph/0604178)

Picture taken from: