In the quantum world, things actually happening because of a clear cause is a total fluke. Most of the time, the universe just doesn't work that way.
March 27, 2026
Original Paper
Causality is rare: some topological properties of causal quantum channels
arXiv · 2603.25315
The Takeaway
Researchers proved that 'causality'—the principle that an effect cannot precede its cause—is a 'nowhere dense' property in the set of possible quantum operations. This suggests that the vast majority of mathematically possible quantum interactions actually break our fundamental understanding of time and logic.
From the abstract
Sorkin's impossible operations demonstrate that causality of a quantum channel in QFT is an additional constraint on quantum operations above and beyond the locality of the channel. What has not been shown in the literature so far is how much of a constraint it is. Here we answer this question in perhaps the strongest possible terms: the set of causal channels is nowhere dense in the set of local channels. We connect this result to quantum information, showing that the set of causal unitaries ha