Question of the behavior of particles in observation

[sshort75]

I've never been formally educated in quantum mechanics but to my knowledge particles' behavior changes when they are being observed or measured. What causes this change and is there any theory as to why, or if it is possible to deliberately change behaviors to a desired outcome?

 

[Jivesh]

That is one of the main questions in QM. What causes the wavefunction to collapse on measurement is unknown. However, a theory called decoherence was developed as a more general concept of wavefunction collapse. By constantly measuring a system, it is possible to keep the system in that state as long as we want. This is known as the Quantum Zeno effect. It has been observed in decaying atoms. The repeated measurement of the state of the atom prevented it from decaying.