Abstract
Attempts to make observations at Planck scales are likely to cause formation of black holes .They will limit the possibility of observation at these scales.Such limitations can be accounted for by making the coordinates of spacetime not commute, just as in quantum theory, the Heisenberg uncertainty principle is taken care of by noncommuting position and momentum. These ideas go back to the 1930’s and Heisenberg and Schrodinger. This interesting history is traced. We then explain the formulation of such quantum spacetimes and their physical consequences. They modify the Pauli principle and lead to Pauli-forbidden transitions.They also lead to violations of causality at Planck scales with observable consequences for cosmic microwave background, Lorentz invariance, equality of particle-antiparticle lifetimes, CPT theorem etc. All these are reviewed in an elementary manner.
