⇒ Universality is a counterfactual property (about what is possible), and it has sweeping consequences: it is universality that permits the existence of a Universal Computer, like the ones we use nowadays.
> This property was first grasped in the Victorian era. At that time, the inventor Charles Babbage proposed a scheme to build what he called the Analytical Engine. This would have been, if realised, the first programmable computer—the ancestor of our modern ones, only far larger and made of brass mechanical cogs and wheels. Ada Lovelace, Babbage’s collaborator and a brilliant mathematician, understood the universality of this machine, conjecturing in her notes that the Analytical Engine could be used to produce all sorts of
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MARLETTO, Chiara, 2021. The science of can and can’t: a physicist’s journey through the land of counterfactuals. New York: Viking. ISBN 978-0-525-52193-8, p. 92.