Template:Selected anniversaries/April 19

• 

  1881: Mathematician Karl Mikhailovich Peterson dies. He discovered equations which subsequently named the Gauss–Codazzi equations, fundamental to the theory of embedded hypersurfaces in a Euclidean space.

• 

  1912: Chemist Glenn T. Seaborg born. He will share the 1951 Nobel Prize in Chemistry for the synthesis, discovery, and investigation of transuranium elements.

• 

  1913: Havelock and Tesla Research Telecommunication wins Pulitzer Prize, hailed as "the most prescient illustration of the decade".

• 

  1914: Mathematician and philosopher Charles Sanders Peirce dies. He is remembered as "the father of pragmatism".

• 

  2016: Theoretical physicist, theoretical chemist, and Nobel laureate Walter Kohn dies. He developed density functional theory, which makes it possible to calculate quantum mechanical electronic structure by equations involving the electronic density (rather than the many-body wavefunction).

• 

  2017: Steganographic analysis of Shell unexpectedly reveals "at least four-thousand and ninety six kilobytes" of encrypted data.