I'm pretty new to quantum physics, so there's a good chance that I have this all backwards.
However, by my understanding of the Copenhagen interpretation, the wave function 'collapses' upon observation. In the many worlds interpretation, the observer becomes decohered and collapse never occurs.
I understand that it's fairly difficult to super-position big things. However, if many-worlds holds correct, then it should be really easy to super-position a human. For example, they observe the result of an experiment. Upon seeing result
A they take a step back. Upon seeing result
B they take a step forward. Bam, we have a massive super-positioned object.
So the question is, is it possible to super-position a human such that they can interfere with themselves in some way? Or at least such that we can measure whether or not they are super-positioned?
For example, perhaps the super-positioned person carries a "photon gun", and shoots it at where his super-positioned self would be. He may not see anything special, but could it be set up such that an outside observer (unaware of where the super-positioned human is standing) could measure the interference between the photons shot by the photon gun?
If so, then it seems that there is an experiment which can differentiate between the Copenhagen interpretation and many-worlds. I've been told that this is not the case, so I'm wondering where my logic failed.