You mean like a new element? We haven't even managed to synthesize all the ones we believe can exist, because they get very unstable. Or maybe a way to make u

You mean like a new element? We haven't even managed to synthesize all the ones we believe can exist, because they get very unstable. Or maybe a way to make up different non-atom things out of subatomic particles and keep them stable? So long as the new thing has some signature on some of our sensor technology we should probably be able to deduce what it is (this is sort of what particle physics folks have been doing for some time). If we were presented with somethign truly novel like this it would be a "drop-everything, go all in on the science" while also sort of reflecting on how little we really know.