Was Lord Kelvin wrong? 3D-printed shape casts doubt on his 150-year-old theory

[Judi Lynn]

By Ben Turner - Staff Writer about 5 hours ago

The weird shape may be more subtle than Kelvin assumed.



One of the team's 3-D printed isotropic helicoids. (Image credit: Greg Voth/Wesleyan University)
A 150-year-old theory about an otherworldly shape proposed by Lord Kelvin, one of history's greatest physicists, has finally been put to the test — and his conjecture is now in doubt.

In 1871, William Thomson, more commonly known as Lord Kelvin — a famed British physicist who made key contributions to electromagnetic theory, thermodynamics, navigation and the absolute temperature system that bears his name — proposed a theory about a strange hypothetical shape, which he called an isotropic helicoid.

The shape resembles a sphere with a number of fins protruding from its surface and looks the same (is isotropic) from any angle. Kelvin believed that if submerged in water and allowed to sink, a helicoid should spin like a tiny propeller.

But a new experiment led by two physics professors — Greg Voth of Wesleyan University in Connecticut and Bernhard Mehlig of the University of Gothenburg in Sweden — has cast doubt on Kelvin's predictions. By 3D printing five different isotropic helicoids according to Kelvin's instructions and then dropping them into silicone oil, the team discovered that the shapes didn't spin as they fell after all.

More:
https://www.livescience.com/was-lord-kelvin-theory-wrong.html?utm_source=notification

[marble falls]

1. Did they try dropping them into water, like Lord Kelvin postulated?