Fixing Scientific Publishing

I have already written in the last post how scientific publishing works. A lot of people has been arguing for open access journals, and there is some good in that. Of course, open access has its own problems, like the fact that you have to pay huge fees and still doesn't have freedom to choose your own copyright rules. 

My favourite site is, of course, arxiv.org. However, in order to make sites like it really work there is a circle that must be broken. It's the funding one. Call it the Funding Feedback Loop if you like. I will use the initials FFL just for convenience here. This is one of the worst things that exist in science today and one of the responsible (if not THE responsible) for the tyranny of the scientific publishers. It works like this.

Science needs money to keep running (as everything else) and, as is common in life, those who really have money to invest in science are not scientists in general. Therefore, they need to decide how to invest their money and where. For simplicity and laziness reasons, the people they hired to make this decision came up with "objective" criteria, which means finding some numbers which are easy to get to create a ranking system. Those people are not really interesting in evaluating the research itself, because this is a complex task which involves thinking and decision taking, and they are not really interested in that. Instead, they do a quick search and find a bunch of indices which seems reasonable.

For some reasons, good ones in the past, some scientific publications became highly prestigious, like Nature and Science. There are others, of course, but they can be ranked by something which is called "impact index", something objective and calculable. No need to think. This, associated with number of citations and things like that, are the dream of the decision taking groups. They just need to gather those numbers and their job is done.

Of course, classifying science according to those numbers is like classifying countries according to GDP. There is a correlation, but ask the poor people of Brazil if the fact that its GDP is high does really matter to them. The problem is that, after people start to rely on the numbers to take the decision, they forget that those numbers are biased, incomplete, full of noise and, in many cases, prone to a lot of corruption and manipulation.

In science, what happened is that people stopped concentrating on scientific knowledge and started to aim in what journal they wanted their paper to be published. The funding agencies only give money to those who publish in Nature, so people struggle to publish in Nature and Nature gets more and more power. The same for other prestigious publisher.

Unless funding agencies stop requiring scientists to publish in certain journals to get funding, there is no way to liberate scientific knowledge simply because scientists need money to survive! Are you going to pay the scientists if the funding agencies don't? Don't try to fool me, I'm pretty sure you won't. But then, how can we break the FFL?

Part of the solution is for funding agencies to stop being lazy and doing a serious job on decision making! But that's complicate! Yes! It is! But if you do easy things the result is invariably rubbish! Everyone knows that, or SHOULD know that! Stop relying on easy reading ranks and do a serious analysis of what is really important in scientific research. That would increase the costs? Yes, it would. There's no free lunch. If you want to do something with quality, you need to invest time and money.

Therefore, to break the monopoly of the powerful publishers, the FFL needs to be broken. In order to do that, the decision taking about funding needs to rely on a more detailed analysis of what to fund. One that relies on the quality of the research independently on where it is published. Invest on that and you start to take power from the publishers. Of course they will react to that, and they will react aggressively! That's because there is a lot of money involved and nobody wants to let it go! They obviously have powerful lobbies. There's obvious a lot of corruption in the system, the kind of legal corruption of course. But the only way to minimise it is to doing the right thing.

So, if you are a serious funding agency, one which is not chained by lobbies or agreements and really wants to invest your money in serious science. If you are a rich person that loves science and want your money invested in a way that really creates free knowledge for future generations, here is my advice:

Take part of the money available for the funding and invest in a serious group of people to analyse the scientific value of the proposals instead of their "objective" measures. Pay them to do a damn good job! Hire scientists who like science to do that analysis job, not administrators. Spending part of the money on that might guarantee a better use of it.

There is only one thing: be careful with corruption on that process! As I said before, there is not free lunch. If you want things to be of quality, you need to be always alert! It's like democracy. If you stop paying attention to it, it gets corrupt.

How Scientific Publishing Works

I have written small posts about this for some time now but the sad loss of Aaron Swartz seemed to help bringing the issue to the headlines. I think it's time to clarify better how scientific publishing worked in the past, how it works now and how it should work. 

However, before starting, I cannot resist but criticise the horrible article from John Gapper entitled Aaron Swartz's illusion over research. Far from me to believe that everything someone says is true, and that includes Aaron. I disagree, although only partially, with many of his views and I might talk about that in other posts. But Gapper writes about scientific publishing in a way that seems that he never actually had to publish. I don't really know if that's true, but it surely looks like.

If you check most blogs from academics, you will see the true side of the story. You should also take as a piece of evidence that a lot (A LOT!) of academics at least try to leave their papers in their websites for free access. Gapper claims that scientific publishers increase the efficiency of the system and that, without them, things would be worse. That might have been true in the past, but only because they added the value of distributing the papers in large scale, something that today can be done by the internet.

He also claims that the quality of free journals with open access would be much lower because the usual journals keep standards. It's not difficult, however, to keep certain standards and the price we pay for those standards is much higher than we should. Of course you have to pay an editor, but remember that journals DON'T PAY ANYTHING TO REVIEWERS, and although editors do an important job, it's the reviewers who go through the papers in details and are responsible for a higher quality standard. 

Okay, I already wrote too much about that article. Let's see how things really are. 

The Basic Idea

In the ideal world, we scientists write papers because we discovered interesting things and we want to:

1. Make our discoveries widespread known

2. Allow other scientists, or anyone who feels capable of, to check our results (hopefully confirming we were right ;) )

In the very past, this was difficult. Even if you don't consider the work in copying your documents over an over again if you don't even have a photocopy machine, disseminating them is a huge obstacle. Before emails, things had to be sent by letter. Printed. That's not efficient at all.

Evolution

The solution, of course, is to publish things in journals, which are then distributed to a certain audience. But think of a newspaper. It reaches more people because people knows where to buy it, are interested in it and effectively go there. Scientific journals were then printed in the universities. However, as you may think, it was still difficult to transmit things far away in space. So, at some point, larger companies took over and were able to guarantee an even larger distribution. They also contributed to a nice formatting of the papers as well, I must say.

That sounds nice, but there are some catches. First of all, these ARE NOT non-profit companies. On the contrary. And as any normal company, they are interested in minimize costs and maximize gains. And they did a pretty good job exploiting the willingness of scientists to be known and their moral convictions. How?

1. Willingness to be known: whatever the reason, scientists like to be recognised. In order for this to happen, you have to make your work known. If people are only reading papers in a journal, well, you might choose not to, but no one will read you. So, because scientists NEED to publish in journals, they started to accept any kind of agreement with them. This culminated in the absurd copyright agreements that still exist today. In other words, these agreements allow the publisher to sell the scientist's paper and forbid the scientist of doing the same. :) And there's more, the journal doesn't pay anything for this copyright. Actually, most scientists are even happy that they don't have to pay for the publication!

2. Moral Convictions: but to keep some standards of quality, you cannot publish anything. You can hire editors, but editors are not specialists in everything. The journals needed specialists to evaluate and correct the papers, but they didn't want to pay much. Actually, they discovered a way of not paying anything at all! They send papers to the specialists and ask them to evaluate the papers. There are, of course, scientists that review paper for evil reasons, like stealing ideas, but they are minority. Usually, we feel compelled to review papers to help colleagues to publish. And also to guarantee that science is being done properly. So, we do that because we are moral. For free.

Then, things ended up this way. We, scientists, give our papers and rights to the publisher. We work for them reviewing for free. They sell everything.

But, unfortunately for those who found an exploitable niche, the world changes all the time. Computers and the internet practically nullified the advantages of publishing in scientific journals. How?

1. Formatting: today, most scientists use LATEX to write papers. You must know that all formatting work done by the publishers today can be summarized in producing a LATEX template and a guide for the authors to do the formatting by themselves! (I have to admit, those guys are damn smart!) LATEX is freely available on the web. If you think LATEX is too complicated, you can always use Word, which unfortunately is paid, or the freely available Open Office. So, formatting today is so easy that this advantage doesn't exist.

2. Distribution: another one that bit the dust. The fact that putting in the webpage and sending by email completely compensated all advantages in distribution publishers can offer is so obvious that here lies the thing against they fight most. Anyone, in virtually any country in the world, can INSTANTLY have access to a paper we upload to our page or to a repository like the free arXiv.

What about quality? Well, maybe this should be the area of focusing of these guys, but they just want a free ride. They should pay reviewers and, if they think they would not get enough profit if they do, than too bad for them. If I want someone to work for me I have to pay, unless I want a slave, be it a willing one or not.

They store the papers and they need to pay for the server and maintenance. They do. True. But think about it. They are just storing the work of others, selling access to it and charging for that. Are you allowed to do that with, let's say, artwork you find in the internet? Of course not, because of the copyright. That's why they need the authors to give it to them. But that's a very easy job and everyone who stores things in mass on the internet has to pay something. Too bad for them again. 

But if they do not offer any advantage today, why do they still exist? Ah... let's see.

Money

Everyone needs to survive. Everyone needs money. Scientists are no different. We really work very hard. As hard as any other hard-worker. But we usually earn less in average. Yes, that's the truth. If you compare our work with physicians or lawyers with the same level of intellectual training... well, it's enough to say that they laugh on us.

But we are proud and we do it for love. But we need jobs. However, contrary to arts or sports, nobody is willing to sponsor us. If we go to the streets and try to sell our papers as artists do with their works, we will starve to death. Some of us can find places in the industry, but most scientists cannot. Those depend on universities.

Universities live on students and funding from agencies. Students are not related to research, they are related to teaching and we can talk about that another time. Agencies, governmental or not, are the ones who allow research to be made. But to get grants, the agencies today use "objective" criteria to select who is gonna get them. One of these is number of publications in peer reviewed journals and in which journal they are published. There you go!

That means that in order to get money for leaving, we scientists NEED to publish in those journals. So, we have to accept their terms, otherwise we don't publish and we don't get jobs. I've seen people saying that you can negotiate the copyright agreements, for instance, like in this article. But the truth is that, if you're not known, is in the beginning of your career or is not in Oxbridge, chances are that you're doomed. In those cases, you do need to publish or your career simply ends. THAT is the main, and maybe only, reason why it's difficult to get rid of the middle man (publishers) today. We gave them a lot of power, it's not easy to take it back...

The Moral, The Ideal, The Right

Is it moral to do what the publishers do? Well, it's business, but you can keep at leas some moral... I think it would be okay for them to store, publish and even charge for scientific papers IN THEIR WEBSITE as long as:

1. Scientists keep TOTAL rights over their papers. The right to disseminate them FREELY if they want to do so. They right even to SELL it if they want to, although nobody will buy it...
2. They PAY reviewers.
3. They accept that, it's business, so if the model is not profitable enough for them, get over it and open another company.

I said IT WOULD, if scientists were not forced to do that, which you've seen is another story.

What about freedom of knowledge? Should scientists be forced to release their papers to public domain? First of all, remember that public domain means that anyone can sell derived work based on that. I'm not sure it's fair. On the other hand, creative commons seems good enough for most purposes. In both cases, I do think that people should be able to read and download for free any government-funded research, but the scientists should be allowed to earn money from that work if he wants to. We need to eat, people.

In all cases, even when the paper has been privately funded, the full copyright has to remain with the scientist. As it has been said many times, no scientist has ever became rich by selling papers, so none of us will charge for people to read ours. It simply doesn't happen!

This means that we couldn't care less if Aaron Swartz was going to spread our papers for free in the internet. I certainly don't about mine! First of all, we never earn anything with those papers and he was not hurting us economically. Only the publishers that forced us to give up the rights. I'm really don't empathize with their melodramatic stories about storing and distributing for the sake of spreading knowledge. They earn much more than me. Secondly, he was doing us the job that should be done by the publisher: dissemination.

Can we eliminate the need for publishers? Can we break the vicious circle that we ourselves created when we had no choice, or when that was a better choice? I think we can. I have some ideas, but I need to work better on them and I will write about it later. What would be yours?

Aaron Swartz (1986-2013)

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PDF Tribute: My papers are here.

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Aaron Swartz committed suicide. He is one of those persons who falls in the same category of people like Julian Assange, people who are most hated by companies and governments in general, because they expose their actual behavior and fight against laws that are nonsensical and stupid. Unfortunately, the time when people like them will be more valued by society than Mark Zuckenberg, Steve Jobs and Bill Gates is far, far away. I wonder if most people can even see what's the difference between them. Today, I will not give any clue. Instead, I will write about the desperate times we are living in.

We do live in desperate times. Well, WE are always living desperate times. But from time to time, desperation hits those who look at us as their assets. Aaron Swartz was being  judged by hacking the site of JSTOR, a scientific publisher like Elsevier (do you remember this one? That from the boycott...), and distributing the content (scientific articles) for free. Although MIT, which administrates JSTOR, decided to drop the charges, the government of the USA decided that they should continue with them, which meant that Aaron was facing the possibility of being forced to spend 35 years (3 5 Y E AR S ! ! !) in jail for the horrible, despicable, inhumane crime of spreading knowledge for free. A crime that no government in the world can leave unpunished.

Let us put things in context a bit. Aaron would spend 35 years together with murderers, rapists and whoever else committed that kind of crime for committing the, once gain, horrible, despicable, inhumane, grotesque, crime of spreading scientific papers in the internet for free. How many years do you get for murder? And for rape? Because, of course, they are basically the same kind of crime as distributing knowledge for free. As Carmen Ortiz, the Attorney for Massachusetts, said “Stealing is stealing, whether you use a computer command or a crowbar, and whether you take documents, data or dollars.” Is there anyone in the 21st century that really believes that every theft, from everyone, in every circumstance is the same? I surely don't.

Yes, it's true that if you do something against the law you should be punished. But remember that taking this literally would mean that it was okay to mistreat black people in South Africa under the Apartheid law. Some laws need to be changed. And some punishments need to be put into context! Come on, we are not naive. We know that many laws are concerned with protecting the interests of those who detain some power, simply because governments rely on them (or are them many times) to remain ruling. All laws, I repeat, ALL LAWS should be continuously discussed and, eventually, changed. Ask all minorities.

Aaron's death brings back many other issues. For instance, the role of scientific publishers today. I wrote many times in this blog explaining that they not only used to force the author to pass to them the copyright of the paper, but also pay nothing for peer reviewing. Today, some "nice" journals just forces you to release the copyright under a creative commons attribution. If they cannot have it, you can't too. :)

The point is that, in the past, these publishers could force those things because the scientists had no other way of mass dissemination of papers. We were forced to accept their terms if we wanted our work to be seen by a larger community. Other ways of dissemination were too limited. But today, we have the internet. We have email. They really don't add any value to our papers that we cannot do ourselves, to be very honest and direct. Because we noticed that, they have to fight to keep their niche in the market. So they use the law, which likes to protect their likes, and lobbies. Yes, lobbies. Everyone in the scientific community knows that to be awarded a grant, whoever is giving you the money will look in what scientific journals you published your papers. And they know that, today, that is the only reason why we still publish on them. It's not because they add anything in terms of science and knowledge, it's because we are chained to this money-feedback-loop.

This, to a lesser extent, also happens in cinema and music. Of course, you must take into consideration the differences in the areas. Still, whenever I rent a DVD I am forced to watch an advertisement saying that if I copy a DVD I'm not better than a thief. I'm not sure what is the penalty for that, but I wouldn't be surprised if that is also harsher than for murder and rape. Now, if you consider that Hollywood movies have profits (PROFITS!) of the order of MILLIONS OF DOLLARS, and in some cases of the order of HUNDREDS OF MILLIONS OF DOLLARS, how do they really want to convince people that if you copy a DVD you're damaging their industry. Of course, you shouldn't do it because it's against the law, but we are looking here at some disproportionate claim. One thing is to say "Don't do it, it's against the law.". I can accept that, because it's the truth, but saying to you that "Don't do it, because you would be an evil people that is destroying the cinema industry" while some movies have a profit of $100 000 000 dollars is outrageous! Again, they misuse the motto stealing is stealing.

I really hope that people don't forget Aaron Swartz or the still-alive-but-we-don't-know-for-how-long-yet Julian Assange. In fact, it's important not to forget the reason why they are persecuted rather than simply their faces or names. As humans, they probably have many flaws which we don't even know (I wouldn't threaten my reputation by any of them, by the way), but the deeds by which their are (or were) being hunted were noble (yes, tacky, but true!). It's also important to know that they are not the only ones that suffered or are suffering for fighting for free knowledge and truth. There are others and, trust me, you will see many more stories in the coming years. I assure you.

By the way, before I finish, I've been reading in many places that everyone is blaming the prosecutor for Aaron's death and calling that person a bully. While that may be true, something I'm not gonna discuss, a deeper truth is that this person is just being a scapegoat for the position and behavior of the government and the lobbies that pressed for it. Don't let them distract you. Please.

Democracy and Frustration

No, this is not a post on statistical physics of disordered systems. It's a plain and simple article about how people get frustrated because the idea they have about democracy does not agree with reality.

What is the idea most people associate with democracy? The school sentence that says that "democracy is the government of the people, by the people and for the people" of course is just marketing. The term "democracy" has origins in Greece (around the 5th century) and is basically the idea that, instead of having just one person deciding things, we can put them to vote. Although as time passes we would like this voting to extend to everyone, that was not the original idea. The vote would be extended to some classes of people.

Is democracy the best system of government possible? No. Definitely no. It's the best we could find, but the system where the majority decides what the minority also has to do can be very unfair, although the tyranny becomes spread to a large portion of the population instead of being from only one individual. It's a logical fallacy, and there are plenty of experimental evidence, that the majority is always right. Even that the majority should have the right to decide about what is best for the community. That's why democracy HAS to be regulated somehow. The ideal way would be a rational one, but people are hardly rational.

But that's not exactly the issue I want to write about, even because that is something that is reasonably well-known. The false expectation I'm talking about is another one, the idea that, in a democracy, the government will try to help the people. Don't get me wrong. That is truly what they should do. Actually, the rulers should be employees like any other. The truth, however, is that they are not.

Let's be honest. Whoever gets power wants to keep it, and that is independent of the government style. That happens as much in South America as in Europe (I know, I lived in both). But it's not enough to stay there, you also want to keep the privileges which make being there worthwhile, which we know are many. One of them is the privilege to take decisions that will benefit yourself.

The fact is that, for those who rule, the rest of the people are seen as an asset. An asset to generate resources and an asset to be used in case of war. This asset has to be managed to fit their objectives, which in general are not the same as the rest of the people simply because the ruler's position of power makes his/her objectives automatically different. A ruler doesn't need to worry about being mugged, or about not having money to eat, or many other things that the citizens in general do.

Now, how do you manage to make people do what you want? The modern way can be summarised by the word "marketing". Marketing is heavily based on playing with people's psychology. And it's rather effective too. The only problem is that, if people start to think too much, they might as well understand what is happening and refuse to follow "the plan". For instance, why would you invade a country that is not invading yours if you're happy at peace in your home? How could people be convinced that decreasing their pensions while not touching the salary of the politicians is the best option when the budget needs a cut?

The answer, of course, is by making people not think. That's what governments do all the time. It's a give and take game, of course. They cannot be too greedy, because today there is a whole moral code among democratic nations. There is the press. It's part of the marketing. However, things like cutting funding for "not practical" research can be done, even with the support of the majority, which never notices that they are being robbed from the right to learn how to think.

So, don't be ever fooled. Even in the most democratic government, the objective of the rulers is to stay there and gather more and more power. They do that bit by bit. It's their nature. The role of the citizen is NOT to trust that the government will do thing right. The role of the citizen is to keep an eye, to complain, to expose whatever is unreasonable and to fight for their rights. If you expect the government to be nice to you, you're just being the kind of naive person they like most and, invariably, will be disappointed.

The Fundamental Axiom of Science

I was checking my list of unpublished drafts (it is reasonably large, I must say) and found an interesting thing. It refers to an old article by now, but as the theme is recurrent, I think it's worth to write about it anyway. 

The article is here and is about the role of faith in science. After some introductory material, the author says that there is something called "the fundamental axiom of science", which I quote here:

Patterns observed in the past enable us to predict what will happen in the future. 

It's also said that Hume argued that there is no rational basis to believe in that and that Kant tried to solve this problem, but failed. Therefore, according to the article, this must be taken as an act of "faith" and that science only works if the axiom is true.

To be fair with the article, I have to say that the author argues correctly that the usual meanings of the word faith have no place in science, but at the end he really confuses me by saying that the above "axiom" of science has to be simply believed if you want to do science. It doesn't. And I will explain why. In the last paragraph, the author gets close to the answer, but he blows it up in the same way as Mt Saint Helens in his example.

So, as always, things boil down to Bayes and I will try to be as brief as possible. The example of Mt Saint Helens given by the author above is a wrong critique to Bayesian inference. It talks about a guy who refused to leave the place after being warned that it would blow up because it had never blown up before, so it would continue like that. The guy died.

In fact, if no one has ever warned the guy, that was the most sensible decision he could take. A sensible decision is not something that leads to a successful result, but one that is the best given the information you have. When the guy refused to listen to the warning, he ignored extra information.

Bayes inference is carried out by taking into account ALL available information, not only what you choose to take according to your personal taste. Here enters the reason why we DO believe in the so-called fundamental "axiom" written above. That's because ALL the information we have today (and I truly mean ALL) points to the fact that we actually can use models to (within limits) make predictions. It's not a question of faith, it's a question of inference. Bayesian inference. Now, if you want to call Bayesian probabilities by the word "beliefs", as it is sometimes done in technical jargon, and if you want to associate this with faith, well, that's up to you, as long as you understand that this IS NOT an arbitrary kind of belief AND CHANGES as more information comes about.

In any case, as all other things in science, if we could never find models that would work, or if suddenly our models stop working, we have to abandon that idea. That is how true science is made. Nothing is a dogma. Everything is subject to change and revision. If you don't like uncertainty, I'm sorry, but that's how science is.

About the "fundamental axiom", I prefer a less pompous name, like "basic working hypothesis", but I don't think that's very catchy.

Negative Temperatures

A friend of mine saw this article from Nature

Quantum gas goes below absolute zero

Ultracold atoms pave way for negative-Kelvin materials

and asked me how is that possible, I mean, how is it possible to have Kelvin temperatures below zero? I gave him a very quick answer, but I think he deserves a more enlightening explanation, so I decided to write this article to explain what's the meaning of a negative Kelvin temperature.

First of all, I have to say that his concern is justified. Although there is nothing very unusual with negative Celsius or Fahrenheit temperatures, the Kelvin scale is constructed in a different way. Without going to irrelevant details, in general the Kelvin temperature is associated with the average kinetic temperature of the molecules (or atoms) of a material. The zero in the Kelvin scale would mean zero kinetic energy, or no molecular movement (either vibrational, rotational or translational). Therefore, in principle, there should be no negative Kelvin temperature as we cannot have less than no energy at all by what energy is supposed to be. (Some of you will say that you can talk about negative energy, but that is not what I mean here. Think of this as differences in energy relative to the ground state, which have to be positive. If someone wants, I can write another post about this later.)

Well, to find out what is wrong here, I need to introduce some concepts, but I'll do that in the most basic way possible. The first concept is that of a derivative. This is a very simple mathematical concept and the only reason why it's not taught in school much earlier is because people are silly. A derivative is a rate of change of one quantity relative to other. For instance, speed is the derivative of space relative to time as it is the amount of space you travel in certain amount of time. You divide one by the other, basically. Acceleration is the derivative of speed with respect to time. There are other examples, and some subtleties, but the idea is that the speed, for instance, allows you to calculate how farI have traveled if you know for how long I've been traveling.

Let's keep using speed as our best example for a derivative. To calculate how much I traveled, I need sticks marking the distance from a zero point in the road. Then I define that the space I traveled is given by the number in the marking I stopped minus the one in which I began. If it's positive, I traveled forwards, if it's negative, I traveled backwards. For instance, if I started on kilometer 4 and finished on kilometer 9, I traveled 9-4=5 kilometers forwards. If I start on kilometer 2 and end on kilometer -3, I traveled -3-2=-5, or 5 kilometers backwards. The convention is that when I calculate the derivative, the sign must be there, be it negative or positive. So if I traveled -6 kilometers in 3 hours, I would say that my average speed is -2 km/h, the minus sign meaning that I traveled backwards with respect to the marking sticks.

By what I explained above, a negative derivative means that one quantity is decreasing while the other increases and a positive derivative means that the it's increasing. But what does it have to do with temperature? To make the connection, I need to introduce some concepts of thermodynamics... and a small model.

Let me start by defining the model and we can use it to understand the rest. The first piece of the puzzle is to understand that what the guys from the paper are looking at is NOT kinetic energy. That's because energy can also be used to define what is called a cost function. You probably learn that all systems try to find the state of least possible energy. This is called a ground state. Whenever the system has more energy than that, it is in an excited state. So, energy is a cost to move the system from its ground state.

When we study thermodynamics, sometimes we look at systems where kinetic energy has no usefulness at all, but there are other measures of cost that will give us an idea about how far the system is from the ground state. One of these systems is a one dimensional line of spins in a homogeneous magnetic field. Calm down, I will explain each term.

The word spin is associated with a property of elementary particles which is very subtle, but what is important for us here is that a charged particle with spin works as a tiny magneto. In order to make it clear on paper we draw a particle with spin as an arrow, where the tip of the arrow is supposed to indicate the north pole of our magneto. A homogeneous magnetic field is a magnetic field which has the same value everywhere in space. As a magnetic field has also a direction, if it's homogeneous the direction is also the same everywhere. Now, if you put a charged particle with spin in a magnetic field and let it go, it will try to align itself with the field. The energy associated with that spin will then be a measure of how misaligned the spin is. The worst case, of course, is when the spin is pointing in the totally opposite direction. I'll draw a picture to make it clearer:

It goes like this. The black lines with arrows represent a homogeneous magnetic field. The green arrows are spins (of electrons, for instance) pointing in some direction. The letters below represent the energy of the spin state in the field. When the spin is pointing in the same direction as the field, the energy is the minimum possible. In the picture I gave the value zero, but the actual number is irrelevant. The important thing is that as you move to the right, the misalignment increases and so does the energy. Remember, physically the spins want to align, so we attribute a number to the state that indicates the amount of misalignment and call it energy. We're almost there.

Now you need to imagine a line of spins in a magnetic field. Each one pointing in a different direction. It helps to introduce right now the concept of entropy. I will not give it in details, but here the association of entropy with disorder is a useful picture. So, if all the spins in a line are pointing to the same direction like this

We can say that the state is highly organized and that the entropy is low. If one of the spins is flipped like this

this state is said to have a higher entropy as it is a bit more disorganized than the previous one. The correct definition of the entropy is achieved by the following procedure. I will use some conventions. I will assume that our magnetic field is ALWAYS pointing upwards and that the spins can have only two positions, upwards and downwards. Then, for each spin, there are only two possible values of the energy to which we will give the value E=0, when it points upwards as the field, and E=1, when it points downwards opposite to the field. The total energy of the line is the sum of the energies for each spin. Therefore, our first line above has energy zero and the second line has energy 1.

The entropy S is related to the number of possible states with the same energy. In fact, it's the logarithm of it. It's easy to see that there is only one state with energy zero (everyone up!) and the logarithm of 1 is zero, so the entropy of our first line is S = 0. There is also only one state with energy 9, as we have nine arrows, it's everyone pointing down. So, again, this state has zero entropy. There are exactly 9 states with one spin down and the rest up, meaning, 9 states with energy 1. These states have, therefore, entropy S = log 9, which is higher than zero, of course.

The final blow is the fact that, a long time ago, we understood that we could define temperature as the derivative of the energy with respect to entropy. This could be done for kinetic energy, but we physicists like to generalize things, and we decided to generalize this definition of temperature even for our line of spins above! Now, let's see the consequences of this generalization. One important thing to bear in mind is that this generalization is not talking about average amounts of kinetic energy anymore. It coincides with that in the case of moving molecules, but surely has nothing to do with it for our line of spins as they are not moving!

Remember that derivatives are rates of change. If we define temperature as the rate of change of energy with entropy, then what happens with the sign of the temperature? If everyone is pointing up and we flip one spin down, we increased the energy and, at the same time, we increased the entropy. So, the temperature is positive and so far so good. 

We finally arrived at the trick! If we start with everyone pointing down, the energy is the highest possible (E = 9) but the entropy is zero (S = 0) because there is only one state with energy 9. If we flip one of the spins up, then the energy will decrease to 8, so the variation in energy will be -1, negative! But the entropy will increase because there are 9 possible states with one spin up and the rest down. So the entropy will increase from zero to log 9. In the same way as our speed, the energy now decreased with and increasing entropy, therefore the derivative is roughly -1/log 9, which is negative! Ta-dah! Negative temperature. Nothing to do with average kinetic energy. Just a trick that plays with the definition.

What the guys do is basically the same thing we did with our line of spins, technically called a spin chain, but in a larger scale. :)

UPDATE: I finally found the footnote I was looking for with a paper of 1956 which deals with negative absolute temperatures. It's a technical paper, but what I would like to leave clear is that, contrary to what I read in many places, this is known to exist for more than half a century:

Thermodynamics and Statistical Mechanics at Negative Absolute Temperatures
Norman F. Ramsey - Phys Rev 103, 20 (1956) - Free PDF

Confirmation

Some time ago I wrote about the Elsevier Boycott and how us, scientists, are stupid enough to give away eternally all the rights of the papers we publish in such a way that sometimes we cannot even access what we ourselves wrote.

Well, a lot of scientific journals have appeared recently with the open access philosophy. We don't have to give up our rights anymore, we can access the articles for free, all we need to do is to PAY a processing fee of ONLY a couple of dollars. For instance, Physical Review X, charges you the SMALL amount of $1500,00 ! Oh, and we actually do not retain the rights, we have to agree to licence the work with a creative commons license. If they cannot own our paper, we can't either!

Well, we are all happy again...

Just to make it clear that we really deserve this, this is the submission guideline of the online sci-fi magazine Kasmagazine:

Payment

We pay a flat rate of twenty-five dollars per story that we accept. Payments are made via Paypal only. 

Legal

Upon having your work accepted by Kasma, you are able to and are automatically giving us non-exclusive electronic publishing rights, or reprint rights if applicable, to publish your story on our website. We do not own your story. You are free to publish and sell it elsewhere, as long as whatever publication you sell it to understands that the rights you are giving them are non-exclusive. After a period of one year, all rights revert back to you and you may, if you wish, ask us to remove your story from our site. We hope that you won't however, as we would like to include your story in our archive of great, short science fiction.

Let's compare with Physical Review X:

Initial submission

Physical Review X is an open-access journal that is financed by article-processing charges to the authors of published papers or to their institutions. The articles are published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Before making submissions authors must take steps to ensure that they or their institutions accept the responsibility for the payment of an Article Processing Charge ($1500 for up to roughly twenty formatted pages) should their manuscripts be accepted for publication.

Ha! We scientists are so smart!