出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/07/03 16:13 UTC 版)
A Roman ring, in theoretical physics, is a configuration of wormholes where for each individual wormhole the time difference across its mouths is such that it may not allow a closed timelike curve (CTC), or 'closed-time loop'. If these wormholes and their mouths are arranged in a suitable configuration, a closed time loop will be again possible.