There is a theory that gravity could pull galaxies back together, causing a reverse big bang.

which observation makes this theory less likely than the idea that the universe may continue to expand?

background radiation is present.
galaxies exist outside of the milky way.
the expansion of the universe is accelerating.
gas giants form farther from the sun, where temperatures are cooler.

Cold case files recently began re-investigating an old murder case. the murder took place in the park; a young man, james, was hit over the head with a brick and killed. police suspected the jealous former boyfriend of james' wife, karen. whoever killed james may have washed their hands in a near-by bird bath as detectives found blood in the bird bath. since the murder took place before dna fingerprinting was available, the suspected killer, ronnie, went free. detectives are now reviewing the blood evidence using dna fingerprinting. based on the dna fingerprints of all possible suspects, who is james' killer?