Exactly, that's the whole point. As long as you don't measure it, you don't know it. But as soon as you start to measure something, you also alter it by examining it.

There is a rather weird experiment for instance, if you take one foton, and you don't look at it, and let it go headed for two holes in a wall. If you don't examine it while it travels it'll go through BOTH holes at the SAME time, because you will see a dispersion pattern which can only be made by multiple projections. Things like that can getv very complicated, and also very interesting.