Inward Bound

Mostly from 1895 to 1945.

The breakdown of the proton-electron model#

From about 1925 to 1934, one sought for a common cure of both the structure problem of nucleus (paradoxes, everyone of which consequences of the presumption that electrons are nuclear constituents) and the \(\beta\)-decay spectrum problem (why are \(\beta\)-spectra continuous?).

• During 1932-4, following the discovery of the neutron, gradual expulsion of the electron as nuclear constituent.
• In around 1930, Pauli's neutrino hypothesis, in contrast to Bohr who proposed a statistical version of energy conservation.

Only after Fermi's application of field theory to \(\beta\)-decay, it was asserted that electrons and neutrinos are created in the very act of \(\beta\)-disintegration. Before that it was believed by many that the neutron itself was a proton-electron composite.