Abstract: A misconception in quantum mechanics is that when the measurement of position or momentum

alone is performed，completely accurate values will be obtained. We take the measurement of position for an oscillator

in a ground state for instance，and calculations show that the oscillator must gain some energy during the measurement

and the amount of the energy increases without bound along with degree of the accuracy. Therefore，neither

position nor momentum can be accurately measured.

Key words: position measurement, harmonic oscillator, energy divergence