using certain principles of quantum physics, one sees that the universe can be affected by the human mind. Alchemy employs that ability of willpower to decompose things down to the basic elements (or even elementary particles, but that requires more energy), then rebuild them, using the Law of Equivalent Trade (the show Full Metal Alchemist gets really close to the science). YOU CANNOT TURN LEAD INTO GOLD. That has been a great arguement over the years, and it has been found that the decay doesnt work right........but lead can be turned into about a quarter its wieght in U-238....