Proofs of the Hot Big Bang (of Georges LeMaitre):
1. The red shift of distant galaxies.
2. The cosmic microwave background. Penzias and Wilson 1976.
     A black body curve at T = 2.7 K results from electrons combining with protons
     to make hydrogen. Ultraviolet stretched to microwave
     with the expanding universe. This has small lumps in different directions of
    about 1 part in 10,000 indicating early inflation.
3. Nucleosynthesis–Burbidge, Fowler, and Hoyle in 1960 calculated
    Big Bang made 75% He, 25% He–observed in unrecycled material.
Georges LeMaitre