The FT Money Machine by Financial Times

In 1949, the economist Bill Phillips created a legendary interactive analogue computer, commonly referred to as the ‘Moniac’. It simulated the flow of money through an economy using hydraulics based on Keynesian economic principles. Users could make changes to taxation, consumption, investment and government spending and see how they would combine to affect national income, interest rates, imports and exports. To achieve this, the machine ingeniously solved nine differential equations every time a parameter was changed and plotted subsequent changes onto time series charts using fluid logic alone: an electric pump, floats, weights, electrodes, and cords rather than semi-conductors!

It was a triumph of engineering, a genuinely interactive, physical data visualisation long before the development of modern computer graphics. Its status as a landmark computing machine is confirmed by its presence in the mathematics wing of the British Science Museum, alongside the works of Babbage, Lovelace and Turing. But, more than just a museum piece, the machine remains unparalleled as a physical teaching device, although just three of the original 14 machines built remain fully functioning today.

Adapting the machine into a digital app would not work for a conventional web app because of the sheer physicality of the original (it is over 2 metres tall!). Based on meticulous measurements and scans of a restored original at the University of Cambridge, the Financial Times and Infosys have developed a fully faithful digital twin in Extended Reality (XR) for Apple Vision Pro.

The new CGI version was modelled in Maya, and textured in Adobe Substance 3D Painter before being brought to life in the cross-gaming platform Unity. Interaction design took advantage of Apple’s Vision OS’ support for eye tracking and gesture recognition, recreating the experience of operating the Moniac with startling realism.

As well as faithfully replicating the workings of the original machine,, the new app includes lessons on the history of the machine and an explainer on the ‘Circular Flow of Money’, which remains a staple of modern high school economic curricula.

An event at the London School of Economics in September 2024 celebrated the launch of the new app as a free download in the Apple Vision Pro app store at the venue where the original machine was introduced 75 years previously. It was a joyous event with a unique audience of eminent economists and high school students - exactly the broad range we think this app appeals to.

To accompany the app, we produced a comprehensive FT magazine front page package covering both the amazing history of the machine and the process of adapting a 75-year-old analogue computer into a canonical example of ‘spatial computing’ using the very latest immersive technology. The online version is free-to-read at ft.com/money-machine.