On the use of common sense in science
Posted by horsservice on April 6, 2010
“If common sense was a reliable guide, we wouldn’t need science in the first place.”
A.Gefter, New Scientist
I have noted that on this blog, the expressions “it’s common sense”, “it’s obvious”, “it’s natural” are widely diffused, and are not often based on realities.
Apart from the fact that there are things that seem obvious for some people but not for others, the goal of this small article is to show you a few illogical but true examples, and that Common Sense is something really fuzzy. We’ll find that the further we go into the “exactness” of the science fields, the more unreasonable it gets.
(I’m not a professional in all of these subjects, and there may be some mistakes there and there.)
Let’s begin with something that, as we all know, isn’t very sensible, but is even less sensible than we would imagine: human behaviour.
In fact, we would imagine that when people know that something is bad for them, they would stop. Generally speaking, at least.
Well, results of studies show that it isn’t the case: people take their decisions almost exclusively based on their feelings, and not based on reasonable thought. It has been particularly shown in state-run programs to prevent the use of drugs and cigarettes among students, e.g. in the USA the D.A.R.E program, which has repeatedly been proven inefficient. In England, a long-time study has been held among a group of young people, which were following education classes on the dangers of smoking and how cigarettes work: in the end, they were cigarette specialists, but the same proportion of them were regular smokers than in the non-educated control group. Even more amazing: in Africa, long-running campaigns are in place to incite people to wash their hands after going to the toilets. Essentially informative, but ineffective. The governments then decided to hand over the problem to advertisement specialists. In a few months, problem solved. The solution? A simple series of TV ads: they were showing usual people, with bacteria marked in bright violet after going to toilets and not washing their hands, passing some violet on to the food they were eating. Disgusting. It worked. It’s something that, and I assert, we are ALL are subject to.
“Reasonable” people have just learned to give an emotional value to reason.
Next step: biology.
Everyone knows the anomalous Platypus, the egg laying mammal, which by the way is one of the many evidences of evolution. But recently, scientists discovered reptilian genes (this was expected) in his genome that date back after the mammals-reptilian separation (this wasn’t expected at all). How did they get here? Well, not sure yet, but viruses are strongly suspected.
In fact, viruses are now presumed responsible for a wide variety of prehistoric genetically modified organisms among all species.
Talking of viruses: Living? Not living? They’re not eating, not breathing, not reproducing by themselves, but they spread. And some of them are very little more than a pack of chemicals. Their classification is still in discussion.
And now that we have viruses, we found that some viruses are infecting other viruses! How is it possible? Where to put them?
And what about prions (responsible for Mad Cow disease, for example)? They are really only degenerated proteins. Living, not living? These days, the line is blurred.
See, not so easy to tell if something is living or not.
You thought that tree couldn’t move? Then you should hear about this mangrove tree of the Rhizophora family. Usually, it’s a normal mangrove tree. But if one of its lower branchs (usually containing roots as well) is cut of from the bulk of the plant, the ends towards the plant begins to die out, as usual. But the end towards the exteriors goes on growing roots! And the branch begins living a life of its own, slowly advancing of 1-2 meters per month. Not bad for a plant, isn’t it?
It has also been widely believed until now that animals could be sociable with the same species, but never between species, except if there is a reward. Several cases have been shown since then of the adoption by groups of animals of different species, without any threat or reward. Monkeys are the usual subjects, but we have a case involving the adoption of a gazelle by a… lion!
There exists one documented case of real humour among animals: a monkey, trained by scientists in sign language, one day answered to a biologist holding a banana “that’s a peach”. With every signs of enjoying the surprise of the examiner, because it was a standard test done every morning with never a mistake until then. Looks like laughter isn’t exclusive to Man any more.
Next step: Chemistry.
We’re supposed to be getting on solid ground here. Like, every chemical reaction is supposed to naturally tend to a consumption of the reactors and a homogeneous repartition of the products. Well, not in the case of “chemical clocks”, or oscillatory chemical systems. Just let the reactors of one of this type of reactions in a glass, homogeneously, and they will create themselves a spatial organisation. Even movement (in theory, even eternal movement, but as usual in science theory doesn’t exactly fits experience). It’s so disturbing that the first chemist to give an example of these reactions was forced to publish in a third-class paper with no reading committee, because every other one said at that time that this was going against the second law of thermodynamics (which states, basically that things go from order to disorder).
It’s supposed that something like that generated the universe.
Diffusion of gas through a solid usually increase when decreasing the thickness of the solid. Normal. Logical. Not true under a certain thickness. At nano-scales, the diffusion of a gaseous specie decreases when decreasing the thickness of the film. How so?! The gas is probably condensing in nanopores, blocking the way for the rest. It took 10 years to get this idea from the astonishing experimental result.
Next step: Physics.
The territory that will blow your minds out!
First of all, Causality: The old Cause/Effect thing, where some on this blog base Science on Determinism. Well, it has been knocked over for like 80 years, by quantum mechanics. Sorry to bring this to you. We know now that what we see of the world is merely a statistical effect: determinism only really works within our scale of proportion. How to explain quantum physics? Basically, it says that there’s random variation from equilibrium everywhere, anytime. Don’t laugh: this mechanism is believed to be the cause of Giant waves (30 m high, formerly legends), impossible waves formed at high sea during storm. They’re random, and they’re deadly. Mechanism also involved in evolution, and in tunnel microscopy for example.
Oh yeah, tunnelling. Did you know that according to quantum physics, an electron can cross an energy barrier too high for it with a non-zero probability? It means something like there’s a non-zero probability for you to pass through a wall. But it works. Of course, according to classical physics and common sense, it’s impossible.
Other exotic properties of everything: electrons and other elementary particles are both a wave and a particle. At the same time. It’s also impossible to know their position and their velocity with exact precision at the same time: it’s the well-know Uncertainty Principle of Heisenberg. I don’t want to go into details, but it’s absolutely fascinating.
Total emptiness has energy! In fact, particles are being generated permanently around us from void. In fact, not really generated as such: they are immediately annihilated with their anti-particle, they don’t exist enough time to be called “particles”. But they exist. A “simple” experiment to prove it: take two movable parallel plates, put them into very good vacuum. They are going to move slowly towards each other, because the pressure of the “waves” (remember? waves=particles) on the exterior of the plates is more important than between the plates, because there is more space available on the exterior of the plates (between the plates and the walls of the box) to put waves in.
The Universe is infinite, but expanding! How is it possible? It is, if his 3 dimensions are shaped into a torus! It would be expanding in the rest of the dimensions, like an inflatable balloon, while at the same time containing everything.
Oh, I haven’t talked about the rest of the dimensions we are supposed to be living in? Probably 11 or 12, depending on the theory used to imagine it.
And now: Mathematics.
Totally illogical. Ok, 1+1=2. But there’s more Real numbers (like square root of 2) than Natural numbers (like 1, 2, 3), but they are both infinite ensembles. And there’s exactly as much Relative numbers ( -1, – 238, 2…) as Natural numbers, even if the ensemble of the Relatives includes the one of the Naturals!
Oh, and 0,999999999999…=1.
Probabilities? Take for example a drop of water. If I’m in a building and letting fall this drop on you from the top, what would be the luck of me hitting you? Then, what would be the luck if I was on a cloud, and not looking? Then, imagine what’s the probability of a drop of water taken randomly in the whole history of Earth hitting me? I’m wet after a storm. That’s certainly a miracle!!
Well, it’s approximately the same principle about the origin of life. Very improbable, but there were so many trials… In fact, extreme and/or improbable phenomena are following non-linear rules, not like normal events. They don’t follow a bell curve. It’s a matter of uttermost interest to insurance companies.
And beware of imaginary numbers: they are based on i. i² = -1. Impossible? They exist, and not only as purely formal tools.
Traditionally, there are 5 axioms that define geometry, as edicted by Euclid. The last one is: by one point exterior to a line, passes one and only one line parallel to the first line.
Logical? But not true: it is perfectly possible to consider that this postulate is false, and then get spherical planes (positive curve, with no parallel to a line passing through a point exterior to this line) or hyperbolic planes (negative curves, with an infinity of parallels to a line passing through a point exterior to this line).
And since Einstein we have strong presumptions that the Universe is non-euclidian.
And there are hundreds of these examples. It’s even worse if you want to understand them, especially the physics and the mathematics behind all that. Some people spent their lives demonstrating that common sense was wrong all along, in sociology, in astronomy, in history…
Some of them got the Nobel Prize for that. Some died for that.
As for myself, I got a headhache.
It’s the job of scientists to try to go against what was widely believed until then. By the way, it’s also one of the reasons why I trust paleontologists and geologists when they say that there is evolution: glory and fundings come to those who discover things going against nature’s laws, at first glance.
Hope you enjoyed. Now be carefull with what you believe is “common sense”;)
To stay comprehensible and to avoid being too long, I’ve made some shortcuts. I you would like some more science, I suggest you get the wikipedia of this examples.
Many thanks to dorian for her kind corrections and advices!
PS: the LHC has started finally his first collisions!!! The Eight marvel of the World is on her way to blow everything that we know about particle physics and the origin of the universe, whatever the results are!! Yay!