Millikan's oil drop experiment has showed that the electric charge in oil drops is quantized, and has allowed a determination of its value to . The experiment has neither proved that the value of the fundamental electric unit is on the order of nor that electric charge in itself is quantized. All it has proved is that electric charge appears in quanta of magnitude in oil droplets. Other experiments which followed Millikan's experiment, like Johnson's shot noise experiment, indicated the same quantization of charge as the one found in this experiment. One might therefore believe that the discussion on whether the charge is quantized in quanta of or appears in quanta of is a purely philosophical one, with little relevance to physics. However, with the emergence of elementary particle physics, it has been showed that there do exist particles with a lower charge than the 'elementary' charge. These particles have a charge of 1/3 times the elementary charge, but under 'normal' conditions they always appear in groups of three, so the elementary charge unit in 'everyday physics' is indeed the one observed above.