Sunday, August 12, 2007

Evolution of beauty & physics

"Beauty", the latest blog post on a Western European physics blog, is about beauty and is, much like many others on that website, very thought-provoking and mostly incorrect.

Let me first mention the less serious aspects of her essay that I don't want to discuss in detail:

The most important point of Smolin's book is that all leading physicists used to be small pimply insecure boys who used math classes to revenge to their peers who got all the girls.
You can see how much Lee Smolin loves the people whom he self-confidently considers to be his fellow physicists. Incidentally, this nasty attack against scientists is a Smolin's tool to promote affirmative action. Whoops. But whom would I support?

First of all, I don't think that Smolin's statement about the inverse correlation is true. But even if there were such an inverse correlation, I would still have mixed feelings about the situation but my sympathies would probably go to the pimply scientists at the end. A scientist can be obnoxious in a certain situation. He can be ugly, he can be sissy, he can be a leftist. But from the viewpoint of eternity, I don't really care about some mostly stupid girls that the giants of science loved as teenagers, and whatever these girls and their boyfriends did that inspired the giants to make their discovery was a pretty good thing. ;-)

What is even more interesting about the quote above is that the author of the blog post I started with or at least Lee admit that (almost?) all leading theoretical physicists were boys when they were young. If the Harvard president said the same thing, the "progressive" segments would fire her and choose another one with XXX chromosomes instead. ;-) Of course, he doesn't mean it this way. What he really criticizes is that physicists and other people feel a relationship between math skills and maleness. What he doesn't say is that this relationship is real.


The author of the original blog post thinks that people mostly want to be tall and not hairy all over their bodies, to have soft skin, white teeth, big boobs, and/or tough muscles, and recommends you junk e-mail to find the right path to these goals. ;-) She also adds blonde hair: this preference is her nation's heritage from their famous chancellor in the 1930s. Incidentally, a recent study found that women only like macho men for occassional sexual adventures but they prefer sissy and feminime men in the long run.

Most of these preferences are well-known, some of them are obvious, while others are silly, surprising, or overly sensitive. I don't want to talk about them individually. What I want to focus on are the mistakes of the original blogger at the top about the general principles. She writes:

However, once we've outlived our evolutionary program that suggests a link between the appearances that are currently considered 'beautiful' and healthy spouses, these labels of attractiveness are destined to loose their appeal...
From a biological viewpoint, this is clearly a wrong conclusion. Quite on the contrary. If we imagine that evolution no longer makes any selection and no longer pushes our species in certain directions, it means that the perception of beauty from the last moment when evolution did exist would freeze and last forever. If innate instincts of humans keep on changing, then it proves that some selection still exists.

This leads me to the other problem with her idea: I don't think that the main assumption is correct. Evolution still acts but the selection looks at very different characteristics than it used to evaluate in the past. Sometimes the selection is perverse and pretty much the opposite than it used to be and/or than it should be according to common sense - but it is still at work. Whether the future generations will like the product of this new kind of evolution will depend on their tastes that can be very perverse, too.

But the future mankind will probably have enough technology that will allow them to afford perverse tastes. I am pretty sure that our tastes would already be perverse for most people who lived a few centuries ago.


The author wants to design or engineer the following generation. I don't know whether it is a joke or not but I will not join her plans at this moment. Seventy years ago, eugenics was a scientific consensus but it has become pretty unpopular even though there's no doubt that some people have only abandoned it because they don't want to hurt themselves in the society. If the author wants androids instead of normal people, she's ahead of time but the result will be the same as in the case of eugenics. It won't work for a few more years or decades.

Back to science

All the topics above have been silly. The real content of the essay I primarily discuss here is summarized here:

Our perception of beauty has developed with evolution. What reason do we have to believe it is good guidance to understand the fundamental laws of nature?
That's a good question but the author of "Beauty" will surely be shocked that this question also has a good answer.

Our perception of beauty is a reflex that allows us to quickly evaluate certain situations, without using our brains for too long. What's important is that different groups of people have different reflexes and different perceptions of beauty. People in general perceive beauty of other people as being correlated with the ability to produce and sustain healthy and safe off-spring. Their perception of beauty of other things is mostly a by-product of the beauty from the previous sentence.

However, people with innate mathematical and physical aptitude simply feel certain things about mathematics and physics in their bones. You may argue that this ability is a by-product of their pimples but it is really not the most important thing. It is more important that they can do it. They either have this ability from the very beginning, or they train themselves to have this ability, or some combination of these two possibilities occurs.

Besides portions of the brain, these reflexes and sentiments use pretty much the same parts of the neural or even hormonal system as other reflexes and sentiments. They end up with similar feelings. That's why these people have a very good reason to use the same word "beauty" as they use for the right "big boobs", if you allow me to choose a representative slogan for the "common type of beauty". This simplification was only chosen to simplify my terminology.

OK, so is the appreciation for "big boobs" useful to find the right fundamental laws of physics? Not really. But it's also a different thing than what I want to claim. I don't think that the intuition of most of the folks for whom "big boobs" are the most important things is the best tool to find the correct theory of quantum gravity. I am talking about those people who actually have a good intuition about physics and who feel what answers are right and what answers are wrong in their bones.

Is that possible? How do these people understand beauty?

See also: Beauty of string theory
Yes, it is surely possible. As I have said, these people have a much more refined understanding of the word "beauty" in the scientific context. In fact, one can define these people as those whose sense of beauty is more tightly correlated with the scientific truth than the sense of beauty found in other people. Although this reflex is certainly not the only quantity that determines how much they find at the end, it is important and it is the topic of this essay.

The term "beauty" is both good as well as bad for the actual criterion that these people use. It is good because their conclusion is often equally fast and reflexive as their conclusions about the beauty of women, among other things. It is bad because the actual algorithms they use to decide about the beauty of a law of physics are completely different from those applied to women. They are, in fact, extremely rational in character.

When such a "natural" physicist decides that certain laws are more beautiful, he has actually run a subconscious algorithm that has determined at least some of the following things:
  • the prettier laws have survived a couple of consistency checks: they don't lead to any contradictions
  • the prettier laws have survived a couple of fast comparisons with a few general or special observational facts that the physicist realizes
  • the amount of agreement seems higher or much higher than in the case of competing laws that the physicists can quickly design, run, and subconciously evaluate
  • the prettier laws are based on a more coherent set of assumptions that imply each other - which is effectively equivalent to a smaller number of independent assumptions
  • the prettier laws have some internal symmetry that is non-trivial and absent for generic laws in wider classes of candidate laws
  • the prettier laws are robust and the same set of principles, constraints, and symmetries determines the laws either uniquely or these laws only have a few parameters; these properties make the laws more likely to be true because the agreement from the first two categories (self-consistency and agreement with observations) has much stronger information value in this case because it can't be just a result of curve-fitting
  • the prettier laws don't have any unnatural discontinuities (such as Hansen's Y2K bug) or other awkward features and assumptions that would be extremely hard to justify; in this sense, the laws are as smooth as "big boobs".

I have probably forgotten a couple of other criteria that are being analyzed at the same moment. But what I want to stress is that if the concept of beauty is used for physical laws by a person who really knows what he is talking about, the concept becomes a rational one - as rational as possible. The criteria above represent procedures that a good physicist should think about even if he uses no reflexes. They are parts of the process.

In each case, if the beauty criterion is satisfied, the candidate laws of physics show that they are more serious candidates than a random guess and they are consequently more likely to be true. You may also say that this rule is a part of Bayesian inference. There's no doubt that the criteria above are positively correlated with validity of scientific theories. 350 years of progress in physics shows that the winning laws have most of the properties above and most of the competing wrong laws are "ugly" in the sense that they don't satisfy them. They have features that do not belong to the overall picture, features that expose an intervention of a human being with a bad taste.

In some sense, and one must be careful about this sense, beautiful laws of physics indeed resemble a beautiful painting. If someone can appreciate this kind of beauty, it really means that he or she is able to look at the whole theory an bloc and efficiently figure out whether there are wrong features that do not belong to the picture (ugly features, apparently added by someone with bad taste instead of Mother Nature) and whether the whole thing fits together. Details of this evaluation surely differ from artists' perception of beauty.

Moreover, physicists' perception of beauty has to evolve if they want to be able to answer new questions correctly. New general characteristics that are found to be associated with correct laws of physics are included in these algorithms and fast, "natural" physicists can imprint these algorithms directly to their wires and use the sense of beauty to get some answers efficiently.

I am not saying that these methods can completely circumvent experiments but what I am saying is that a person with much more refined sense of scientific beauty doesn't need a lot of observational input that others would need, and can get the right answers anyway and faster. This is something that pure thought is able to do - it is like predicting one "big boob" using your reflexes about beauty and another "big boob" although the analogy is not 100% perfect. ;-) But the point is that with the sense of beauty that is really nothing else than a concentrated hard-wired gadget to perform complicated intellectual operations involving complex interconnected frameworks of objects and ideas, one can deduce things that couldn't be deduced without these chips.

Generic people haven't been trained to evaluate candidate equations of quantum gravity or other segments of physics. That's certainly the case but this fact agrees with the principles above because generic people are also not those who can successfully use their perception of beauty to pick the right solutions. It's the people who have actually been trained to judge these things correctly - either by evolution, genes, schools, or their own research.

I am almost certain that every theoretical physicist who has been a sort of visionary (or "seer" if you wish) has been using some fast reflexes and sentiments to determine the right directions or answers in many situations and these fast reflexes may be interpreted as "perception of beauty" even though some of these people would prefer to avoid this language.


There is nothing wrong about beauty and it has been a key tool in theoretical physics for at least 350 years and probably much longer. Even though ugliness is not enough to falsify a candidate law of physics, perception of beauty as sketched above is a legitimate component of a rational, quantitative, Bayesian evaluation of the likelihood of various theories. A majority of the candidate laws that are eventually eliminated by the natural selection of science - the falsification process - can be shown to be ugly according to the most refined criteria of scientific beauty. Scientists' perception of beauty is constantly evolving so that it is imperfectly optimized for finding the right answers.

Finally, let me quote two obvious physicists and some extra ones.

"A physical theory must possess mathematical beauty." That was the epigraph that Paul Dirac chose in 1956 when asked to express his view of the essence of physics. It is the guy who unified all existing forms of quantum mechanics, extracted the common features of all quantum-mechanical theories, and reconciled quantum mechanics with relativity in his theory that also predicted anti-matter and that controls all elementary particles of matter (I mean fermions) that we have observed so far.

Needless to say, Albert Einstein agreed with this position. He once went so far as to say that "the only physical theories that we are willing to accept are the beautiful ones." These two Gentlemen are responsible for quite a significant portion of the 20th century physics and their equations often compete for the "most beautiful equation" award.

Richard Feynman would always emphasize that a disproven theory must be abandoned even if it is beautiful. But no doubt, he saw beauty in our description of a flower at all distance scales, too. ;-)


  1. Evolution is a mythology but...

    If evolutionists want to end the arguments all they have to do is, get their brilliant heads together and assemble a 'simple' living cell. This should be possible, since they certainly have a very great amount of knowledge about what is inside the 'simple' cell.

    After all, shouldn't all the combined Intelligence of all the worlds scientist be able the do what chance encounters with random chemicals, without a set of instructions, accomplished about 4 billion years ago,according to the evolutionists, having no intelligence at all available to help them along in their quest to become a living entity. Surely then the evolutionists scientists today should be able to make us a 'simple' cell.

    If it weren't so pitiful it would be humorous, that intelligent people have swallowed the evolution mythology.

    Beyond doubt, the main reason people believe in evolution is that sources they admire, say it is so. It would pay for these people to do a thorough examination of all the evidence CONTRARY to evolution that is readily available: Try The evolutionists should honestly examine the SUPPOSED evidence 'FOR' evolution for THEMSELVES.

    Build us a cell, from scratch, with the required raw material, that is with NO cell material, just the 'raw' stuff, and the argument is over. But if the scientists are unsuccessful, perhaps they should try Mother Earth's recipe, you know, the one they claim worked the first time about 4 billion years ago, so they say. All they need to do is to gather all the chemicals that we know are essential for life, pour them into a large clay pot and stir vigorously for a few billion years, and Walla, LIFE!

    Oh, you don't believe the 'original' Mother Earth recipe will work? You are NOT alone, Neither do I, and MILLIONS of others!

    PS: Please don't lie about the 'first life' problem, scientists are falling all over themselves to make a living cell. Many have admitted publicly that it is a monumental problem. And is many years away from happening, if ever. Logical people understand this problem and have rightly concluded that an Intelligent Designer was absolutely necessary. Think of it this way, if all the brilliant scientists on earth can't do it how on earth can anyone believe that it happened by accident?????