 Some have argued that common-sense flow-of-time theories can be compatible with eternalism, for example John G. Cramer’s transactional interpretation.Kastner (2010) "proposed that in order to preserve the elegance and economy of the interpretation, it may be necessary to consider offer and confirmation waves as propagating in a “higher space” of possibilities.In "Time Reborn", Lee Smolin argues that time is physically fundamental, in contrast to Einstein's view that time is an illusion.