In quantum mechanics, the act of observation or measurement determines certain properties of subatomic particles. The specific properties that can be determined through measurement depend on the particular experiment and the observable being measured. Here are a few examples of properties that can be determined through observation:
Position: The position of a particle can be determined by making a position measurement. This collapses the particle's wave function, providing a specific value for its position at the time of measurement.
Momentum: Similarly, the momentum of a particle can be determined through a momentum measurement. This measurement collapses the particle's wave function into a particular momentum eigenstate.
Spin: Subatomic particles, such as electrons, have an intrinsic property called spin. Spin can be measured along a particular axis, such as the spin component in the z-direction. A measurement of spin collapses the particle's spin state into a specific value along the measured axis.
Energy: The energy of a particle can be determined through energy measurements. Energy eigenstates are associated with specific energy values, and a measurement collapses the particle's wave function into an energy eigenstate.
Polarization: For particles like photons, polarization is an important property. Polarization measurements can determine the orientation and state of polarization of a photon.
These are just a few examples of properties that can be determined through observation or measurement in quantum mechanics. It's important to note that the act of measurement disturbs the quantum system and collapses the wave function into a specific state corresponding to the measured value. The specific outcome of a measurement is typically probabilistic, and repeated measurements on identically prepared systems can yield statistical distributions that reflect the quantum nature of the particles.