Hello! I'm an Engineer by profession with less knowledge of physics, so please be basic with me. After recently being intrigued by the double slit experiment, I started to read more and more about the same. At most of the places, it says that as soon a sensor is kept near one of the slit to find out which slit the electron passes from, the wave nature of the electron collapses and the interference pattern disappears, i.e. a "conscious mind" collapses the wave function. My question is, is it the act of measurement that is causing the change or is it just the sensor that is altering the particle nature? I mean, if I shoot a particle and a sensor is mounted at one of the slits, but I am not measuring which slit it is passing through; will I see an interference pattern? Will the electron behave as a wave like it normally would, or will the wave function collapse and particle like properties will be seen? It may be a basic question but please bear with me and explain. Thank you.