Ask Ethan: Could The Fabric Of Spacetime Be Defective? (Synopsis)
“Weakness of character is the only defect which cannot be amended.” -Francois de La Rochefoucauld
So, you’d like to ruin the fabric of your space, would you? Similar to tying a knot in it, stitching it up with some poorly-run shenanigans, running a two-dimensional membrane through it (like a hole in a sponge), etc., it’s possible to put a topological defect in the fabric of space itself. This isn’t just a mathematical possibility, but a physical one: if you break a symmetry in just the right way, monopoles, strings, domain walls, or textures could be produced on a cosmic scale.
The differences between a Universe created according to standard cosmology (L) and one with a significant network of topological defects (R) give vastly different large-scale structures. We have good enough observations to rule out cosmic strings and domain walls as being a dominant component of the modern Universe. Image credit: Andrey Kravtsov (cosmological simulation, L); B. Allen & E.P. Shellard (simulation in a cosmic string Universe, R).
These could show up in a variety of ways, from abundant new, massive particles to a network of large-scale structure defects in space to a particular set of fluctuations in the cosmic microwave background. Yet when it comes time to put up or shut up, the Universe offers no positive evidence of any of these defects. Save for one, that is: back in 1982, there was an observation of one (and only one) event consistent with a magnetic monopole. 35 years later, we still don’t know what it was.
In 1982, an experiment running under the leadership of Blas Cabrera, one with eight turns of wire, detected a flux change of eight magnetons: indications of a magnetic monopole. Unfortunately, no one was present at the time of detection, and no one has ever reproduced this result or found a second monopole. Image credit: Cabrera B. (1982). First Results from a Superconductive Detector for Moving Magnetic Monopoles, Physical Review Letters, 48 (20) 1378–1381.