The word “quantum” comes from the Latin quantum (“how much, how much”) and the English quantum (“quantity, portion, quantum”). It has long been customary to call the science of the motion of matter “mechanics”. Accordingly, the term “quantum mechanics” means the science of the motion of matter in portions (or, in modern scientific language, the science of the motion of quantized matter). The term “quantum” was coined by the German physicist Max Planck (see Planck’s constant) to describe the interaction of light with atoms.
Quantum mechanics often contradicts our common sense. And all because common sense tells us things that are taken from everyday experience, and in our everyday experience we have to deal only with large objects and phenomena of the macrocosm, and at the atomic and subatomic level, material particles behave quite differently
. The Heisenberg Uncertainty Principle outlines the meaning of these differences. In the macrocosm, we can reliably and unambiguously determine the location (spatial coordinates) of any object (for example, this book). It doesn’t matter if we use a ruler, radar, sonar, photometry or any other measurement method, the measurement results will be objective and not dependent on the position of the book (of course, provided that you are careful in the measurement process). That is, some uncertainty and inaccuracy are possible – but only due to the limited capabilities of measuring instruments and observation errors.
To get more accurate and reliable results, we just need to take a more accurate measuring device and try to use it without errors.
Now, if instead of the coordinates of the book we need to measure the coordinates of a microparticle, for example, an electron, then we can no longer neglect the interactions between the measuring device and the object of measurement. The force of the action of a ruler or other measuring device on the book is negligible and does not affect the measurement results, but in order to measure the spatial coordinates of an electron, we need to launch a photon, another electron or other elementary particle of energies comparable to the measured electron in its direction and measure its deviation.
But at the same time, the electron itself, which is the object of measurement, as a result of interaction with this particle, will change its position in space. Thus, the very act of measurement leads to a change in the position of the measured object, and the measurement inaccuracy is due to the very fact of the measurement, and not to the degree of accuracy of the measuring device used. This is the situation we have to put up with in the microcosm. Measurement is impossible without interaction, and interaction is impossible without affecting the measured object and, as a consequence, distorting the measurement results.