The CMB Cold Spot, a temperature depression reaching roughly -150 microkelvin at its core over several degrees of sky, sits along a line of sight that passes through the Eridanus supervoid, and the natural hypothesis was that the void explains the spot: an underdensity that deep should chill crossing photons through the integrated Sachs-Wolfe and Rees-Sciama effects (Finelli et al. 2014; Kovacs and Garcia-Bellido 2016).
The arithmetic refused to cooperate. Within ΛCDM, the measured depth and size of the Eridanus supervoid account for only a small fraction of the Cold Spot's depression, and lensing constraints rule out a single void deep enough anywhere along the sightline to close the budget (Zibin 2014; Mackenzie et al. 2017). The standard model is left in the worst of both positions: it cannot explain the Cold Spot with the void, and it cannot explain why an improbable supervoid and an improbable cold spot sit on the same line of sight if they are unrelated. Dismissing the alignment as coincidence costs probability; accepting it as causal contradicts the model's own ISW physics.
The standing is a stalemate with sharpening instruments. The void is confirmed and mapped; the Cold Spot is robust across CMB missions; the connection between them is the open question. Deeper void profiling from DESI and dedicated cross-correlation of void catalogs with Simons Observatory and CMB-S4 maps will measure how much cold the void actually contributes, and how much remains for something else to explain.