411 REFERENCE · Wiktionary
Roman ring
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Etymology
en why Roman?
Noun
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.
en Black holes Hypothetical means of transport Relativity Time Time travel