[PvK]

I haven't been paying a lot of attention to new physics for over ten years, but Last I heard, practically all of our ability to observe all phenomena was fundamentally electro-magnetic. Therefore, it's quite difficult to prove the existence, not to mention the non-existence, of phenomena which have zero or near-zero electro-magnetic effects.

There could be entire classes of phenomena which we simply haven't observed, because we haven't noticed any interactions with our senses or equipment.

PvK