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Quite some time ago (perhaps 12 years ago?) I was loaned a novel which I cannot remember the name of.
Someone invents a way to create stable wormholes in time too small to travel through, but used to view events in the past. Results in the removal of all personal privacy, crimes are watched in court from any angle - nothing can be hidden. People begin to walk around wearing masks with projections from these wormholes on them, so you could be wearing the face of a Roman Centurion with his facial expressions changing in real time. I don't remember too much else about the finer plot.
Pretty thin on description, but if it sound familiar to you....