1: The cosmological red shift of galaxies and quasars
2: The Cosmic Microwave Background Radiation
3: The ratio of hydrogen to helium in the Universe
4: The existence of heavy elements in stars (and Earth!)

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1: ... electrons first combined in large numbers with protons to form atoms.
2: ... the first helium nuclei were formed.
3: ... light elements combined to form heavy elements.
4: ... photons first decoupled from electrons to spread freely through space.

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1: ... they will eventually stop at the outside boundary of the Universe.
2: ... we can work backwards in time, much like running a videotape in reverse.
3: ... the Universe will eventually 'evaporate' out of existence.
4: ... it will eventually stop and fall back in on itself.

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1: about 5-6 percent.
2: about 24-25 percent
3: about 50 percent
4: None of these are correct because the helium abundance in the Universe cannot be measured.

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1: about 1000 Kelvin
2: 98.6 Kelvin
3: just under 3 Kelvin
4: Absolute zero

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