Durante il periodo natalizio, Radio3Scienza ha chiesto a scienziati, storici, scrittori, attori e giornalisti di raccontare storie di scienza. La serie si chiama "Io ti racconto" e andrà avanti fino al 6 gennaio, quindi c'è ancora tempo per iniziare adesso (e recuperare le puntate precedenti sul loro sito).

Nella puntata dell'ultimo dell'anno, io ho provato a raccontare la storia di un errore che non c'era: quello di Einstein e della costante cosmologica. La puntata si riascolta qui. Continue reading →

Qualche tempo fa, quel genio di xkcd provò a spiegare come funziona un Saturn V usando solo le mille parole più frequenti della lingua inglese. Che non sia facile lo si può intuire, ma bisogna provarci per capirlo davvero. E allora qualcuno ha creato un editor che vi bacchetta se usate una parola non inclusa nella lista. Funziona solo in inglese, ma non dovrebbe essere difficile farlo in altre lingue.

Io mi sono divertito a raccontare in modo semplice una cosa che conosco bene. Ne è venuta fuori una storia buona da leggere durante le feste, magari aspettando la mezzanotte.

HOW EVERYTHING THAT THERE IS CAME TO BE

We now have reasons to believe that everything started a long long time ago, from very hot matter that filled all space. At that time, matter was in a very different state from anything we see around us today. It was made of very tiny pieces, flying very fast in every direction. At the beginning, everything was too hot for the pieces to stay together and form larger things. Much hotter than a star, in fact, so that there was also a lot of light all around.

But the space between things got bigger and bigger as time passed, and things cooled down all along. Then, the tiny pieces of matter started sticking together and forming other, slightly bigger pieces of matter, which then joined with other pieces, and so on. Then, things calmed down for some time. Everything went dark, and there were all those tiny pieces of matter around.

But, from the very start, there were some places in space where there happened to be a little bit more matter than in other places. Slowly, as space kept getting bigger and things kept cooling down, more and more matter was pulled toward those places. After some time, there was really a lot of matter in those places, and some balls of matter kept getting heavier and heavier, and hotter and hotter, until they lit up and became stars, and in the end there were huge groups of stars every where.

We now live inside one of those groups, on a ball of rock flying around one of those stars. It took a very long time, but forces acting on matter formed everything we see around -- and us, as well. That's how the story went. It's a great and long story, and we were able to figure it all out. Well, most of it, at least.

Ah, and you know what? We can still catch the light that was there at the beginning. We can not see it with our eyes, but it became a noise filling all space, so that we can listen to it using some sort of big strange phones, so to speak. And we can also make pictures out of it. Cool, huh?

Of course, there are many things we still don't know. There is a lot of dark stuff all around: in fact, we think that this dark stuff is most of the stuff that there is. We can not see it, though, and we have no idea of what it is. But we need it to explain many different things: how the big groups of stars can turn around as fast as they do and still stay together, or why space is growing faster and faster.

We still have to figure out this part of the story. And one day we will do it, I guess. Continue reading →