this poll refers to this other thread https://www.physicsforums.com/showthread.php?t=81295 when I first read the "sum over topologies" papers linked there, i was very optimistic. Loll and Westra have been able to make the CDT path integral in 2D sum over topological variation the topological variation allowed in the sum is carefully controlled, it is regulated using their causal layer structure. they are able to allow microscopic variation (like that envisioned by Wheeler in the "foam" image with its tiny wormholes) but to prevent large-scale weird stuff from happening. this all sounds good, but can they make this work in 3D spacetime, and ultimately in 4D? I have been thinking about this and now I am not sure that Loll etc. will be able to do this. Topo variation is inherently more controllable in 2D. what do you think? I invite you to record your hunch about this in the poll here. It is public so we know who guesses what and check back. Frankly, right now I am undecided! I used to feel confident they could jack this result up to 4D and now I dont.