[gmt2027]

Max Planck famously said science advances one funeral at a time. J. J. Thomson discovered the electron through his work on cathode rays in 1897. Up to that point the orthodoxy was that atoms were the smallest unit of matter. However there was evidence from the mid 19th century. What Thompson actually did was finally come up with incontrovertible experimental confirmation of a subatomic particle. The electron and other subatomic particles were the gateway to the rapid advance of 20th century physics.

The same pattern repeated itself in the early 20th century. Truly revolutionary ideas may take a generation to gain popular acceptance.

They had vacuum tubes in the 19th century, atomic theory and Maxwell's equations by the 1860s. I find it difficult to believe that they were incapable of isolating the electron.