Imminent Science by Giovanni F. Bignami

Author:Giovanni F. Bignami
Language: eng
Format: epub
Publisher: Springer Milan, Milano

Nowadays are we already able to operate a connection between the Universe and our “living” selves, that is to follow the fil rouge from Big Bang to humankind? More or less, in the sense that there are at least a couple of gaps in the fil rouge, albeit regrettably important ones. The first we already saw: it is that initial moment, brief (10−43 s) but crucial, in which the whole of physics was born and we don’t know how. Then, and here we are faring much better, matter was born, and cosmological nucleosynthesis among lighter elements in the first 3 min took place, as it did a little later (a few hundreds of millions of years later? Not so very little), when stars were turned on. From such stellar nucleosynthesis (the final explosive stage included) come the elements we know, such as Iron, Calcium, Uranium and so on. Including the mythical CHNOPS cocktail included (Carbon [C], Hydrogen [H], Nitrogen [N], Oxygen [O], Phosphorus [P] and Sulphur [S]), upon which our own chemistry is based.

But to arrive all the way to the making of us humans, stars began first to make interstellar grains, that is specks of cosmic dust scattered among stars or wrapped around them like a warm cocoon. From stardust we can also arrive at the formation of planets (would you say this is something Immanuel Kant taught us in 1755?), starting unerringly from circumstellar matter that organises itself around a newborn star and that then clots up like porridge. But this inter- and circum-stellar matter is also the one in which ever more and more complex cosmic organic molecules take shape.

Here something very interesting can be immediately remarked. To make complex molecules the ideal is to shape up a sort of framework of multipurpose atoms, that is atoms able to hook up in a multiple and stable way both with each other and with other atomic species. Then up crops our friend Carbon, the best in his class in building complex structures. By means of radioastronomy and infrared astronomy from space, in the sky we have up to now discovered over 110 molecules based on Carbon, including some rather strange organic things, such as HC10CN (H = Hydrogen, C = Carbon, CN = Cyanide), a sort of cyanoacetylene, only more complex. No other atom is by far as clever as carbon in making up complex molecules: the second one is Silicon that yet only makes up one-tenth of it.

Then of course we receive and constantly analyse the great quantity of organic molecules, even very complex ones that reach us on board meteorites. They are objects that have been falling onto the Earth since it was generated 4.67 billion years ago, at the respectable pace nowadays of 40,000 tons a year (earlier on in the life of Earth they were certainly more numerous). They carry on board a most interesting sequence of organic molecules of increasing complexity, up to the so-called “bricks of life”. They are sugars and, most of all, amino acids, which are also present in minor bodies in the Solar system, for instance.

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