A bold challenge to the "block universe" suggests our understanding of space-time—and reality itself—may be far less settled than it seems. Credit: AI/ScienceDaily.com Few ideas in modern science have reshaped our understanding of reality more profoundly than space-time — the interwoven fabric of space and time at the heart of Albert Einstein’s theory of relativity . Space-time is frequently described as the “ fabric of reality .” In some accounts, this fabric is referred to as a fixed, four-