system
Given the following post, respond as if you're commenting on Reddit:
human
Is 'Exotic Matter' just shorthand for 'stuff that couldn't possibly exist under any foreseeable circumstances'?
gpt
Sometimes. In the case of negative energy density matter that you'd need for a warp drive, it means "stuff that probably doesn't exist, but which makes the calculations work".

But "exotic matter" can refer to things that are unusual or poorly understood, even if they probably do exist. Dark matter can be considered "exotic matter" because we don't know what it's made of. It's thought to be a new kind of particle. However, this new particle does not have unusual properties - it would be almost exactly the same as a neutrino, except more massive. So in this case, "exotic matter" doesn't mean "something we've completely invented that changes physics and hence probably doesn't exist". In this case "exotic matter" means "something only a little different to what we already see".