Two thoughts on this. If the Milky Way is one hundred light years in diameter and Andromeda is 2.5 million light years away that means Andromeda is 25 times the diameter of the Milky Way distant from us. That's not much. When will they merge? And I wonder how long it will take for the merging to take place. That is from the time the two just start to touch to complete merging. I ask because I wonder if in the process of merging and the resulting disruption if any of solar systems if there would be time for earthlike life to evolve. And then it's been found that the furthest galaxy is about 13,230 million light years away (according to Wikipedia) and that means it's about 5300 times further than Andromeda from us...I think. Having said that ( I finally used that worn out phrase) if you take one of those corkboard pins with the round colored head and call that 1/8 inch in diameter then Andromeda's pin would be 3.125 inches from the Milky Way's pin and the furthest galaxy's pin would be (1/8" = 100,000 light years. and 13,230,000,000 / 100,000 = 132,300/8= 16,538 inches...and 16,538 inches=1,378 feet or about a quarter mile away) from Earth's pin. Anybody want to check this?