Problem
Fantasy physics: all charges positive. What would happen if only positive charges existed in nature, and no negative ones? Discuss the effect on the existence of neutral atoms, on ordinary matter and on the role of gravity.
Solution
Neutral atoms impossible. The neutrality of an atom arises from the balance between positive protons and negative electrons. With only positive charges there would be no opposite charge capable of compensating: every aggregate of matter would remain globally positively charged and a neutral atom could not exist.
No bonds, no ordinary matter. Chemical bonding and the cohesion of solids rest on attractions between charges of opposite sign. If all charges were positive, the Coulomb force between any two of them would always be repulsive:
Every charge would flee from all the others, and macroscopic structures (molecules, crystals, solid bodies) would fall apart: ordinary matter as we know it could not form.
Role of gravity. The only attractive interaction left would be gravity. But at the atomic scale it is extremely weak — dozens of orders of magnitude smaller than the electric repulsion — and therefore entirely insufficient to hold the charges together. Gravity would dominate only on enormous astronomical scales, not on the atomic one.
Linked atoms
Topics: Elettrostatica Concepts: Carica elettrica Skills: Analisi di casi limite e fantafisica