Last week I posed the question: What is the greatest invention of the 20th century -- other than computers and anything related to computing?
The answers you gave were very interesting. Many were items I never would have thought -- the interstate freeway system, the Dada Art Movement, or the Pill. I find it equally interesting that some items were not mentioned -- like genetic manipulation, or refrigeration.
Here in alphabetical order are all the items nominated as the greatest invention of the 20th century, and the year they were invented (which, in some cases, is a matter of debate). Some things, like broadcasting, were invented in stages over several years; so I chose the date of the first regular broadcast as the date it was invented.
Airplane - 1903 if you believe the Wright Brothers theory; 1906 if you believe the Alberto Santos-Dumont theory.
Antibiotics - 1944, streptomycin
Atomic Bomb - 1945
The Beatles - 1960
Broadcasting - 1920, the first regular radio broadcast to an audience
Dada Art Movement - 1915
Interstate Freeway System - 1956, as the National System of Interstate and Defense Highways Act
Penicillin - 1928
The Pill - 1960
Plastic - 1907, first entirely synthetic material
Polio Vaccine - 1952
Sliced Bread - 1928
Sulfa Drugs (antibacterial) - 1935
Tampon - 1929
Television - 1922 - 1939, first broadcast