Indeed they do. Although the gravitational field of a galaxy is extremely weak by earth or solar system standards, a galaxy's gravitational field encompasses so many millions of cubic light years that the cumulative weak effect becomes the dominant force acting between galaxies in the universe. These effects can be so powerful that they can tear apart entire galaxies, shred their delicate spiral patterns, and cast their constituent stars into the dark abysses of intergalactic space. The above Hubble Space Telescope photo shows two galaxies colliding and creating quite a mess.
Copyright 1997 Dr. Sten Odenwald
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