26 février 2010

13 énigmes qui confondent la science moderne

Je viens de me taper ce livre intitulé "13 Things That Don't Make Sense: the most baffling mysteries of our time". Le site officiel est ici.

J'ai adoré. J'ai dévoré ce bouquin comme d'autres se taperaient un roman à l'intrigue extraordinaire. Je n'ai pas de formation spéciale en science, je suis juste un type curieux, et cela ne m'a pas empêcher d'adorer et de comprendre... presque tout. Je l'avoue, y'a des bouts où le gars me perdait... mais la plupart de temps, je suivais sans problème.

L'auteur, Michael Brooks, est un journaliste scientifique britannique. Il tient également un blogue ici.

Alors, je vous sens trépigner d'impatience... quels sont ces 13 mystères que la science moderne est incapable de résoudre? Voici un court résumé des chapitres, en quelques mots.

1- L'univers manquant (ou la matière noire):
If you take our best understanding of gravity, apply it to the way galaxies spin, and you'll quickly see the problem: the galaxies should be falling apart. (...) there is not enough mass in the galaxies to produce the observed spin. The best response from physicists is to suggest there is more stuff out there than we can see, and that the gravity of this stuff is holding everything together. Just as they called the mysterious accelerating stuff dark energy, they call this mysterious gravitating stuff dark matter. We’ve been searching for dark matter for decades now, but we still have no idea what it might be.

2- L'anomalie Pioneer:
(...) the Pioneer probes are of interest (...) because they are drifting off course in a very intriguing way. In every year of travel, the probes veer 8000 miles further away from their intended trajectory (...) and decades of analysis have failed to find a straightforward reason (...) So it is possible that these errant spaceprobes are telling us something extraordinary. Maybe Newton’s law of gravitation, the law that describes how their trajectories should be playing out, is in need of an overhaul. Or is there is a new and strange force waiting to be discovered?


3- Des constantes... variables?
The laws of physics might be rather more flexible than we thought. The physical laws and constants have helped us define and tame the natural world. But what if there are no immutable laws? What if the constants aren’t constant? Or, as Webb puts it, a wry smile playing across his lips, “Who decided they were constant, anyway?”

4- La fusion froide?
Over a 10-year period from 1989, US navy labs ran more than 200 experiments to investigate whether nuclear reactions generating more energy than they consume - supposedly only possible inside stars - can occur at room temperature. Numerous researchers have since pronounced themselves believers.
 
5- Qu'est-ce que la vie?
THIS might seem like a strange thing to label as an anomaly, but no one knows what life is. Researchers have even given up trying to define it. Now they are just trying to understand it by making it from scratch. It sounds like an audacious, ridiculously ambitious project, but it isn’t really. After all, what makes you so special? You are made up of lifeless chemicals; what makes you alive?
 
6- De la vie sur Mars? Ou alors quoi?
JULY 20, 1976. Gilbert Levin is on the edge of his seat. Millions of kilometres away on Mars, the Viking landers have scooped up some soil and mixed it with carbon-14-labelled nutrients. The mission's scientists have all agreed that if Levin's instruments on board the landers detect emissions of carbon-14-containing methane from the soil, then there must be life on Mars. Viking reports a positive result. Something is ingesting the nutrients, metabolising them, and then belching out gas laced with carbon-14. According to all the criteria, this should have triggered a party: it was a sign of life on Mars. But, despite the evidence, NASA said it wasn’t life.
 
7- A-t-on capté un signal d'une civilisation extra-terrestre?
IT was 37 seconds long and came from outer space. On 15 August 1977 it caused astronomer Jerry Ehman, then of Ohio State University in Columbus, to scrawl "Wow!" on the printout from Big Ear, Ohio State's radio telescope in Delaware. And 28 years later no one knows what created the signal.
 
8- Le virus géant
IN a freezer in Marseille, France, sits a virus that is by far the biggest virus known to science; it is huge, around thirty times bigger than the rhinovirus that gives you a common cold. (...) Mimivirus doesn’t fit with the established story of how life on Earth got going. Viruses are not classified as alive, yet Mimi has a genome that, in parts, looks like yours. Mimivirus seems to be part of the story of life on Earth – and it may even rewrite the book of life itself.
 
9- Pourquoi la mort?
WHY do living things die? Obviously, things kill each other – that’s part of the natural order. But what causes “natural” death? It is a question that splits biologists. It has become like a game of ping pong – over the years, theories have been batted back and forth as new evidence comes to light.
 
10- L'énigme du sexe
NO one knows why we reproduce by having sex. All the arguments in favour of sex are countered by stronger arguments in favour of self-cloning: asexual reproduction, where an organism produces a copy of itself, is a much more efficient way to pass your genes down to the next generation. The puzzle is, why hasn’t asexual reproduction taken over? Asexual reproduction does exist in patches of the natural world, but sex is everywhere.
 
11- Le libre arbitre est-il un mythe?
EVERY day, we live under the spell of an illusion: that our conscious mind is autonomous, and in control of our bodies and decisions. We think we have free will, yet as neuroscience digs ever deeper into the mystery of the human brain, that delusion becomes harder to justify. We are, as one neuroscientist told me as he used a powerful magnet to take control of my body’s movements, brain-machines. This runs contrary to our every impulse. Our gut instinct, our experience, is that we make the decisions to move, to think, to eat, to steal, to lie, to punch and kick. We have constructed the entire edifice of our civilisation on this idea. Is science wrong when it says free will is a delusion? If not, what does it mean for our sense of self? And for our morality – can we prosecute people for acts over which they had no conscious control?

12- L'effet placebo
IT used to be thought of as just a manipulation, a mind-trick. Doctors wore white coats, spoke in soothing tones, exuding confidence and medical know-how, and if they told you a pill would make you better, it would. By the time you found out it was just a sugar pill, you were feeling great, so who cares? The placebo effect works. Or does it? Recent experiments suggest things are a lot more complicated than that.

13- L'homéopathie
Homeopathy’s claim is that you can take a substance of dubious properties, dilute it to the point where there are no molecules of the original substance left in the sample you have, and your sample will nevertheless have retained healing properties related to the original compound. There is no justification in all of science for this idea -- and yet there remains some slim evidence that homeopathy works.

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