When we imagine a large nuclear physics laboratory we might think of a place where energy is produced, like in a nuclear power plant, or of a place where more efficient ways of producing energy are studied. Or even a place, like a large particle accelerator, where elementary particles such as protons are brought to an energy corresponding to that prevailing at the birth of the Universe.

  The Gran Sasso Laboratories are none of this. In the Laboratories electrical power is used to run the electronic devices of the experimental apparata. Energy is neither produced nor converted into particles (with a small exception that we will describe that later).

Inside of the BOREXINO experiment sphere
Photo> PAOLO LOMBARDI INFN-MI/LNGS

    It is now appropriate to give a very sketchy description of our Universe.

   From a merely anthropic point of view, the Universe can be considered as a gigantic (in fact the biggest possible) machine producing energy, or, better, converting gravitational energy into all kinds of radiation, especially light and heat (that are indispensable for life).

   This description of the Universe does not intend suggesting a causal connection: this is only what man thinks the Universe produces. It is fair to add, however, that even a Universe slightly different from this would make antropomorphic life very difficult. Let’s now take a snapshot of the Universe when it was only a few hundred million years ‘old’ (its age is now estimated to be approximately 14 billion years). At that stage, the Universe contained matter (essentially hydrogen and helium with traces of some heavier elements) and possibly some form of exotic matter that nowadays is called ‘dark’.
 

There was also very little light: stars had not yet formed 

This ‘almost’ is extremely important: if the gas filling the Universe had been completely uniform, it would have been extremely difficult for the present Universe to emerge. Being matter distribution not exactly uniform, gravitational force was stronger where matter concentrated. These concentrations of matter attracted more matter, that generated more gravity… and so on until “structures”, (that is Galaxies and stars), were formed. Matter was no longer uniformly distributed but in clumps, more or less like in the present Universe.
 

Inside of the BOREXINO experiment sphere
 Photo> PAOLO LOMBARDI INFN-MI/LNGS