In my space sci-fi story set in the 2340s, I opened it with Helen musing on the small menorah on her table and the Hanukkah she celebrated a year prior (well, it's three paragraphs into the story, but still.) I had also planned for one of the other major characters, Lt. Heridon Copper to celebrate Christmas and sometimes later in the story, Helen ponders what he would like and even helps him decorate his cabin with a tree and Christmas ornaments. Question: would it be realistic for them to still celebrate their respective holidays in the 24th century? You'd think that after meeting the various alien civilizations over the centuries, they would kind of also incorporate their holidays into their own. To sum it up, is this realistic? Should they be celebrating other holidays? On a tangent, what of holiday/religious holiday music. If I had Heridon whistling Rudolf the Red-Nosed Reindeer while at his station, what would you think? Would they also still be singing the classical songs or would it be better for me to make up new holiday/religious holiday songs they would sing this far into the future?