Every minute, million of particles coming from the sun pass through our bodies—and their trajectory continues, passing right through the planet. It is as if "matter" simply did not exist to them. We are speaking of course, about neutrinos: the particles "without mass." These miniature mischiefs (recent investigations of which reveal that they actually do possess mass) are the most difficult subatomic particles to study for modern physicists, mainly because they basically do not make any impact against atomic structures on their journeys to who-knows-where. Due to their tiny size they pass through everything, as though they were ghosts. What's more, thanks to a few neutrinos which have actually been able to be observed with the latest technology, (by special detectors set-up in the middle of the South Pole) confirmation of the existence of more than three dimensions of space could now almost be a reality. These great laboratories, buried several tens of meters under the Antarctic ice, can detect the tiny sparkles that are made when a high-energy neutrino (trillions of which bombard us every second) crashes into an atomic nucleus of the layer of ice which make up the walls of the installation. Analyzing these studies, scientists of the Amanda laboratory have concluded that it is very probable that Superstring Theory (ST) has hit the nail on the head in as far as it suggests that apart from the three spatial dimensions in which we now live, there must actually be 9, 10 or even more. The million dollar question is: why can't we perceive more than the three dimensions in which we live? The answer is simple, but at the same time also very complex to understand: the extra dimensions of which ST refers would be tiny, smaller than the diameter of an atom. But being unable to mentally visualize a fourth spatial dimension is nothing to be alarmed about. Brian Greene, one of the pioneers of ST, said "I've never found anyone who could visualize more than three dimensions", "it's very complicated when your own mind is implied in a world that seems to have three dimensions, and is well adapted to visualize that world." Another view quite different from that of multiple dimensionality is being investigated by scientists of NASA. Using computerized models they have taken to the task of creating thousands of possible parallel universes, as though they were bubbles. According to the experts, these spheres (called universes) could either possess a set of physical laws similar to those of our universe, or could well have adapted themselves to a completely different set. This opens the classic, spooky sci-fi possibility that each person has many "versions" of themselves in each one these similar universes. It is further thought that these universes could be at times connected, and at other times separated, at times making travel between them impossible. Whatever the case, NASA knows that it is treading on somewhat difficult territory, especially when it comes to which of these theories are to be presented as real and which simply imaginary. According to studied published in The Scientific American , at the moment four theories of possible multi-universes are proposed (also called multiverses): Level I or open multiverse: it postulates that the number of possible universes are as many as bubbles of a certain diameter that can exist. Since the volume of each bubble is finite, it leads to the conclusion that each certain universe is repeated in all its possible variants. Level II or bubbles: these universes would be separated by each other by an empty space. This empty space would expand faster than it would be possible to travel through. They would also have, in addition, different basic conditions as well as different fundamental physical constants. Level III or the interpretation of many worlds: in these universes, whenever a quantum function collapses, the universe unfolds itself into as many "versions" as necessary to realize all possible results. Level IV or the last assembled theory: universes with other mathematical structures leading to fundamental differences in physical laws.