Re-inventing the lightbulb

[pamphonica]

As an aside, we went from not just cats whiskers but also FETs (first patented by Lilienfield in 1926) to "hollow state" and then back again! The only reason we couldn't have workable FETs (actually thin film MOSFETS) in the 20s was that Lilienfield could not get the silicon pure enough to get a usable "gain" in the device. It took 20+ years before the materials science caught up enough for practical transistors to emerge.
Jeremy