Here's an initial proposal, on the plane of ideas only:
1. General relativity
2. Quantum field theory
3. DNA and the genetic code (or: the "New Synthesis" of Mendel + Darwin,
if this included the knowledge that genes are encoded in DNA)
4. Goedel's theorem -or- the concept of the Turing machine
5. The neuron hypothesis - published by Ramon y Cajal (sp?) in 1900, I think!
-or- the connectionist concept
I am assuming that pre-20th century ideas like atomism and evolution will
survive.
-- -mitch http://desire.apana.org.au/~qix