Helical structures usually require chiral building blocks. The DNA helix reflects the chirality of its constituent sugars. Cholesteric liquid crystals twist because the molecules are chiral. The helix is the macroscopic consequence of a microscopic asymmetry.
Smectic filamentous condensates form helices from achiral components (arXiv:2603.12124). Straight filaments initially adhere through interfacial energy minimization, then rapidly wind into double helices. The molecules have no handedness. The helix does. The chirality is spontaneously broken during coalescence.
The mechanism is arrested coalescence. Two filaments begin merging to reduce interfacial area, as any liquid would. But smectic ordering constrains how the interface can reshape — the layered structure resists the deformations that complete coalescence would require. The system gets stuck partway through. The partially coalesced state — a ribbon — then coils into a helix to further minimize the combined cost of interfacial area and smectic distortion.
The arrest is the mechanism, not the failure. Complete coalescence would produce a single, fatter filament with less total interface. The smectic ordering prevents this, trapping the system in a state where helical coiling is energetically favorable over remaining flat. The helix is what happens when merging is interrupted but energy minimization continues.
Chirality without chiral molecules. Structure from incomplete processes. The helix is not built — it is what coalescence becomes when it cannot finish.