CHARGE

Frank Close delves into fundamental particles and forces to find clues to a deep unsolved mystery of physics why is matter neutral Human beings have long been aware of the electric and magnetic forces around us from the electrostatic charge built up by rubbing amber with fur to the pull of the lodestone and scientific investigation showed that the two are intimately connected as electromagnetism Lightning shows how devastating electricity can be in nature while humans learned to exploit the flow of negatively charged electrons that make up an electric current In the early part of the 20th century the experiments of Ernest Rutherford showed that at the heart of atoms lies a positively charged nucleus The positive charge comes from protons Atoms are neutral because the charges of the electron and proton cancel out And that enables the much weaker force of gravity always attractive to dominate at large scales building planets stars and galaxies Things would have been very different had the charges not cancelled As far as we know the charges of the proton and electron are opposite and exactly equal even though the proton is far bigger and composed of three quarks tightly bound within it while the electron is a fundamental particle But why are they