Final answer:
Edwin Hubble's ideas about the Hubble sequence conflict with several theories of galaxy evolution. These theories propose different mechanisms for galaxy formation and challenge the notion that elliptical galaxies evolve into spirals over time.
Step-by-step explanation:
Edwin Hubble's ideas about the Hubble sequence, also known as the Hubble turning fork diagram, suggest a specific scheme for galaxy evolution. According to Hubble, elliptical galaxies should evolve into spiral galaxies over time. However, several theories of galaxy evolution conflict with Hubble's ideas.
One theory proposes that massive elliptical galaxies formed in a single, rapid collapse of gas and dark matter, during which most of the gas was turned quickly into stars. This contradicts Hubble's idea of a gradual transition from ellipticals to spirals.
Another theory suggests that the differences between galaxy types are related to the rate of star formation. Ellipticals are said to have all their interstellar matter converted rapidly into stars, while spirals have a slower rate of star formation. This contradicts Hubble's idea that all galaxies evolve from ellipticals to spirals.