If he or she is made of antimatter, you will both annihilate in a big flash. The reason for the observed asymmetry between matter and antimatter has so far not been resolved, but it is believed that the origin is cosmological, i.e. that it results from some particle-physics process in the very early universe. Many astrophysicists now believe that this magnetic field has evolved from a primordial field, i.e. one that existed before the galaxies even formed. The next section talks about such phase transitions. In both cases H 2 O remains the same type of matter, but its phase changes.
Phase transitions happen naturally in the early universe, because it cools when it expands.
When the universe goes through a phase transition it changes appearance, just as water does when it turns to ice, but essentially remains the same universe. Such strings would interact with matter and could have important consequences for the clumping of matter in the early universe and the formation of galaxies. Cosmic strings would also give rise to a very particular kind of irregularity in the cosmic microwave background radiation . This is the radiation left over from Big Bang which is still reaching us from all corners of Cosmos. A cosmic string would show up as a rather sharp silhouette against this background, and such a signature will be detectable in either of two very precise experiments, called MAP and the Planck Surveyor, that will soon be operating on satellites in orbit around the earth.