> Antimatter... it may be possible to find or scrape together an approximately Earth-sized chunk of rock and simply to "flip" it all through a fourth spacial di

> Antimatter... it may be possible to find or scrape together an approximately Earth-sized chunk of rock and simply to "flip" it all through a fourth spacial dimension, turning it all to antimatter at once. Obviously this idea is entirely speculative, but I haven't heard of it before and was wondering what the theoretical foundation for it is. I think it's alluding to a 4D rotation causing a change in parity, which seems plausible. Physics is very nearly symmetric under a conjugation of parity and charge (the CP symmetry, which is violated only by the weak nuclear force); so the idea would be that a change in parity through this 4D rotation causes a charge conjugation, maintaining CP symmetry. I don't think this would work. Symmetries in Physics imply a conserved quantity, through Noether's theorem. The problem is that the conserved quantity associated with a charge-conjugation symmetry is not charge itself, but 'charge parity', a multiplicative quantum number. Under CP-symmetry, the product 'charge parity' * 'spatial parity' is the conserved quantity, so a change in spatial parity from the 4D rotation would cause an associated change in charge parity (assuming CP symmetry), which merely means the system would behave differently under a charge conjugation operation, not that the charge is actually changed. Charge conservation itself originates from the gauge invariance of electromagnetism, and I'm not sure how that would be affected by this scenario. I'm not saying the idea is necessarily wrong, but I think it's likely to have originated from a misunderstading. For further information: - https://en.wikipedia.org/wiki/Symmetry_%28physics%29#Conservation_laws_and_symmetry https://en.wikipedia.org/wiki/Symmetry_%28physics%29#Conserv...