On 3 September 2026 the Ig Nobel Prizes left the United States for the first time and landed at the Kongresshaus Zürich, as AP reported. Four researchers walked onto the stage in bright yellow raincoats to collect the physics prize for designing a urinal that barely splashes. The raincoats were a joke. The research was not.

The team is Zhao Pan and Kaveeshan Thurairajah at the University of Waterloo, Randy Hurd at Weber State University and Tadd Truscott at KAUST. They published the work in PNAS Nexus in 2025 under the title “Splash-free urinals for global sustainability and accessibility: Design through physics and differential equations” (DOI 10.1093/pnasnexus/pgaf087). The EurekAlert release that came with the paper gives the core finding in one line: “when the flow of urine impinges on the surface of the fixture at 30° or less, splashback is greatly reduced.”

That is the whole rule. A jet that grazes a surface slides along it. A jet that hits a surface head-on comes back as droplets. So the design question turns geometric: which curve shows the same shallow angle to the stream wherever the stream lands, at any height? Mathematicians call this an isogonal curve, one that crosses a family of lines at a constant angle. Here the answer is a logarithmic spiral. Pan put it plainly to ASME: “We have to solve differential equations, and the solution that governs our urinal is the same as the equation that governs the Nautilus seashell.” The work produced two designs, Cornucopia and Nautilus. Waterloo’s own news story points out the pun: Nauti-loo.

For about a century the default fixture was a bowl, a surface that meets a falling jet at close to a right angle. The industry then added mats, signage, chemicals and cleaning rotas to manage what the bowl kept producing. Nobody was the villain here. The default was. Every wet-floor sign was a geometry problem wearing a hi-vis vest.

The scale is not trivial. Per the EurekAlert release, replacing the 56 million urinals in US public restrooms with the Nautilus “would prevent one million liters of urine from splashing onto the floor each day.” Each litre is cleaning water, detergent and labour never needed. The trade-off is just as plain: a spiral surface is harder to cast and fit than a stock bowl, and all of its performance depends on the angle. If the mounting height drifts on site, the rule drifts with it.

Then comes the accessibility twist. ASME reports a standard version and a lower, ADA-accessible version, and the Nautilus works for children and wheelchair users across a range of heights. One curve serves many bodies. Anyone detailing obstacle-free rooms to SIA 500 will recognise the value of one surface that works for everyone instead of a separate “accessible” fixture.

←TODAY: A 2025 PNAS Nexus paper turned a 30° impact rule into two fixtures, and Zurich gave it a prize.
→3012: In Zurich-3012 every wet surface is drawn backwards from the jet: angle first, shape second.
Fulcrum: The physics is old. The care lay in treating a humble fixture as worth a differential equation.

Atelier: Wet rooms, balcony drips, facade scuppers and green-roof outlets all receive a jet or a drip, and offices usually draw them as shapes, not as impact angles. The same rule applies to all of them. Monday move: add one line to the office’s wet-room and drainage detail checklist, “jet impact angle ≤ 30°, checked in section”, and apply it to the next detail that leaves the studio.

Hack: Draw a surface that meets every incoming ray at the same 30° angle. In this simplified planar version, rays leave a single point. A logarithmic spiral r = a·e^(bθ) crosses every ray from its centre at a constant angle ψ, where b = 1/tan ψ. Paste this into a GhPython component in Rhino 8 and feed the points to Interpolate Curve:

import math, Rhino.Geometry as rg
psi = math.radians(30)            # impact angle the jet sees, everywhere
b = 1 / math.tan(psi)             # log-spiral growth that holds psi constant
ts = [i * 0.05 for i in range(21)]
pts = [rg.Point3d(0.05*math.exp(b*t)*math.cos(t), 0.05*math.exp(b*t)*math.sin(t), 0) for t in ts]

Change psi to 60 and watch the curve close up into something bowl-like. That shape is the splash. We teach this kind of small parametric check, sized for one detail, in PAZ Academy’s Grasshopper courses.

Pan, to the University of Waterloo: “Without physics and math, we cannot design a humble urinal, let alone anything more complex. With a pinch of art and humour, our ordinary, everyday lives can be just a bit better.” Thurairajah added: “This prize is kind of a symbol of that, of learning things just to be learned. Even if it seems a little silly or funny, it’s beautiful to know about how the world works.”

Open your next wet-room section, find the surface the water hits first and measure the angle.