Thursday, 22 December 2011

There's no "Science crisis of Faith"

I don't like to much to criticize other people's work, but came to learn that it's an important part of letting people aware of the wrong things that appear in the press. Not only that, it's important also for people to know that even scientists are not error-proof and free from prejudices. Even Nobel Prizes. 

But I am not going to criticize the work of a Nobel Prize, even because such works usually are technically accurate, at least accurate enough to deserve the prize. I am going to criticize a horrible, horrible popular science article that I read recently. This one:

It's full of logical fallacies, prejudices and misleading sentences, although they are probably not intentionally so. So, let's analyse it. The title already is intended, of course, to draw attention. Anything that relates science to faith is certainly going to attract many readers. The scientists because they always get annoyed with that, the believers because they are always delighted in seeing how those arrogant bunch of scientists are just as believers as they are. Let's then excuse the title, as anyone knows that publishers need to draw attention. As much as I don't like it, I also learn that marketing IS necessary.

The first paragraph is okay. As usual, it talks about the fact that the Greek thought about almost everything first. In this case, about the atomic theory. They just did not have enough technology (in all senses) to verify that. So far, so good. The second paragraph is a bit dubious, but I will skip it as I don't want to be too pick at this point. Then comes the next paragraph, which I will quote almost in its entirety here:
(...) Dramatic developments in cosmological findings and thought have led some of the world’s premier physicists to propose that our universe is only one of an enormous number of universes with wildly varying properties, and that some of the most basic features of our particular universe are indeed mere accidents—a random throw of the cosmic dice. In which case, there is no hope of ever explaining our universe’s features in terms of fundamental causes and principles.
You can already notice the beginning of the "authority argument" here. Of course, in this case, it must be partially excused as the author is not an expert in the field. I just want to remind the reader that even if ALL world's premier physicist's believe in something, even though it doesn't mean that it's true. Now, the last sentence is just nonsense. Even if our universe is just one among many with different physical properties, that doesn't mean that we cannot explain features in terms of fundamental principles. The variety of universes would itself be a principle! But let's continue, I'll talk more about that later on at the appropriate place. Let's take an excerpt of the next paragraph.
(...)Alan Guth, a pioneer in cosmological thought, says that “the multiple-universe idea severely limits our hopes to understand the world from fundamental principles.” And the philosophical ethos of science is torn from its roots. As put to me recently by Nobel Prize–winning physicist Steven Weinberg, a man as careful in his words as in his mathematical calculations, “We now find ourselves at a historic fork in the road we travel to understand the laws of nature. If the multiverse idea is correct, the style of fundamental physics will be radically changed.”
Two authority arguments here again. Guth and Weinberg are really competent physicists, but that doesn't mean that their philosophical views are correct. When Guth says that the multiverse idea "limits our hopes to understand the universe from fundamental principles", he's talking about HIS hopes, or better, what he thinks that fundamental principles are, whatever it is. And to let it clear, NOTHING in the ethos of science is torn from it's roots, because science is based on evidence and if evidence says so, that's the right thing to think independently of our prejudices. Now, Weinberg may be correct in say that the style of PART of fundamental physics changes only because most theoretical physicists are happy to share the same group thinking about philosophy, which again, might be absolutely wrong. All Weinberg is saying is that they will have to revise their "beliefs" in face of new evidence, which is actually what science is all about. Hardly any problem from the scientific point of view, but maybe a large one from the HUMAN point of view... Now, things get worse. Let's see some parts of the next paragraph.
Theoretical physics is the deepest and purest branch of science. It is the outpost of science closest to philosophy, and religion.
I happily can accept the compliment to theoretical physics, but the allusion to religion here is absolutely unnecessary, wrong and only a means to draw the attention of the reader once more. Besides, all science is close to philosophy. Philosophy underlies science and precedes it in the exploration of possibilities. They are, in some sense, interlinked. Religion is another story and science, no matter what branch, IS NOTHING LIKE RELIGION. Scientists may be religious though. Many are. Next bit.
Experimental scientists occupy themselves with observing and measuring the cosmos (...). Theoretical physicists, on the other hand, are not satisfied with observing the universe. They want to know why. 
That represents a huge prejudice against experimental physicists. I'm a theoretical one, but I doubt that my experimental friends are only interested in taking measurements for the fun of doing it. Some may be, but I doubt that it's the majority. They are also driven by the curiosity of understanding, they just have other abilities. Just that. Everybody wants to know "why", the problem being that different people are differently satisfied with the answers. Moving on.
The underlying hope and belief of this enterprise has always been that these basic principles are so restrictive that only one, self-consistent universe is possible, like a crossword puzzle with only one solution.
The author is talking about the idea that it's possible to find a set of principles that uniquely leads to our universe. That's, however, is only an idea. That is not the fundamentals of science. It's a hypothesis and can be as wrong as any other hypothesis. Again, although many scientists believe in it, that might simply be wrong and good scientists have no problem in admitting that. Now, after talking about string theory, multiverse, internal inflation and calling ALL theoretical physicists "Platonists" without a clear meaning, the author jumps to this conclusion:
 We are living in a universe uncalculable by science.
Of course, that's just a sensationalist sentence. In truth, the correct one would be that, according to THOSE theories (which might be wrong) many laws of our universe may not be uniquely determined or constrained. We still can pinpoint a set of axioms and constants though from which we can calculate things. It's just that they are not the way many of us expected. Well, IF it's correct, get over it. That's life. But we can still calculate things, believe me. There is no risk that the universe around us will suddenly fall in total chaos. A bit ahead, there is a sentence from Guth:
“Back in the 1970s and 1980s,” says Alan Guth, “the feeling was that we were so smart, we almost had everything figured out.”
That's actually what Guth thought. Lord Kelvin thought that as well in the 1900's, just before Relativity and Quantum Mechanics. We would hope that 80 years later, scientists would know better. In fact, I think that most do. In fact, the next paragraph reveals that Guth was only talking about his OWN expectations:
“The reason I went into theoretical physics,” Guth tells me, “is that I liked the idea that we could understand everything—i.e., the universe—in terms of mathematics and logic.” 
Which is a completely personal opinion which might not be shared by other physicists. Not by me, for instance. But who am I, right? (I love authority arguments... People fall so easily for them...) Then, the next paragraph contains all that old nonsense about how life could not evolve if the laws or constants of the universe were different. I don't need to say that this is based on a largely prejudicial and short sighted view of what is life. There is no reason to believe that life could not arise with a different set of physical laws. All that discussion is just, in a way, trivial as it says that life is the way it is because those are the numbers and would be different if the numbers were different. By the way, let me say something once more, the weak anthropic principle IS TRIVIAL. The strong is religion and, therefore, not science.

The next two paragraphs reveal something scaring about the author. He really considers that "Intelligent Design" is a solution, it's simply not appealing! I hope that was just an impression, but it really looks like that. Then, it's said that the multiverse solves the fine tuning problem. Honestly, there is not really a fine-tuning problem, in the sense I have already argued. The multiverse might though be an alternative explanation why we see the laws and constants we see. It's, at least, a solution if we cannot find a set of laws that restrict the possibilities to the ones we observe. Again, it's a possibility which, to be honest again, is not in any sense more philosophical appealing by any rational arguments unless the theories that lead to it become more and more plausible with more evidence. With respect to the example of dark energy as fine-tuning, I don't really get it. The alleged fine-tuning seems more like a consequence of poor understanding of its nature than anything else.

In fact, at the end of the article, it's clear that the author hopes is that science becomes more like religion and he says that scientists are not used to take some beliefs on faith as theologians are. Well, you bet not! And I hope that doesn't change. As I said, science IS NOT like religion and should NEVER be. As much as the multiverse might be an interesting idea, it must be supported by evidence and NEVER EVER took for granted just because some people say so.

The most important difference between science and religion is that NOTHING in science is exempt from being questioned. Scientists may take it wrongly many times because we're humans as well, but that's our fault.

Tuesday, 20 December 2011

Bayes and Particle Physics

I have just read a very nice paper on how badly confidence levels are interpreted as probabilities of events in Particle Physics:

It explains well how the frequentist hypothesis-test language can be misleading, to say the least. To be honest, it's amazing how after so many examples of how the Bayesian (although it should be called Laplacian) reasoning is the correct way of doing probabilistic inference, people still are stubborn enough to reject it by the silliest reasons.

It's extremely simple to see that the frequentist approach is a particular case of the much more general, Bayesian framework (once more, read Jaynes or Sivia). The last arguments I heard were related to quantum mechanics. Some people say that, because probabilities are fundamental on QM, the frequentist framework is the correct one. That's nonsense, of course. QM probabilities are still Bayesian. They give the odds of a result given the preparation of an experiment. Obviously, as always, they coincide with the frequentist calculations in the long run, but still, whenever your quantum state is |+>, you can safely say that the probability of measuring a spin up or down is the same, even if you do only one experiment (not an infinity amount of them). The meaning is simply that you don't have any reason to prefer either result, up or down, in your next measurement.

The important thing to remember is this: frequentists cannot say that your NEXT coin throw have a probability of 1/2 tails and 1/2 heads because that should be meaningless for them (although it can be masked by a lot of tricky justifications). On the opposite hand, that kind of reasoning is totally allowed by Bayesian inference, where it has the simple and intuitive clear meaning that there is no reason to favour either tails or heads.

That should be simple, isn't it? In this case, it is.