Short story with a time loop initiated by aliens studying humans for one million years

Question

Back in the 80s I read a story in an anthology book, in which unseen aliens "invade" Earth and force everyone to relive the same day over and over. They do this in order to thoroughly study humanity and find out what makes us tick. At the end of 1 million years (!), the experiment will be over and they'll grant everyone immortality.

The main character argues with his wife that morning, so ends up having the same argument every day for years. Eventually he meets a haunted looking woman on his daily commuter train. She tells him she's a "ghost." She dies in an accident on the loop day, and has to relive her death over and over. Worse yet, once the experiment's over, she'll die one last time and won't become immortal.

Answer 1

This may be "Absent Thee From Felicity Awhile" by Somtow Sucharitkul. There is a description here:

And speaking of Somtow, I recall someone asking about a short story last fall which they had the plot to and wanted to know the title and author. The story involved the Earth being forced into a time loop which made everyone repeat the same day over and over again as a study project for a sort of inter-galactic elementary school. The only reprieve the people on Earth get is two free hours every day early in the morning. Talk about being stuck in a rut... Well, anyway, in case that someone is still wondering, I just recalled those details; it's: "Absent Thee from Felicity Awhile..." by, of course (ah, that's the connection!), Somtow Sucharitkul. Hope my answer didn't come too late!

I found it by looking at the Literature section of TVTropes's Groundhog Day Loop and noting that one mentioned aliens and a million years.

It appeared in Analog Science Fiction/Science Fact, September 14, 1981 among other locations.

I don't see any text of it available online, but the following excerpt shows up in the the Google Books preview:

Gail stirred uneasily. We had breakfast, and I didn't slap her face.

Answer 2

Pretty sure that story was "The Giftie Gie Us" by Timothy Zahn, originally published in Analog July 20 1981 and later collected in Cascade Point and Other Stories (looks like you can get it on Amazon). I remember that story too and think about it from time to time.

1. Aliens observe human beings who are caught in a timeloop which repeats the same day for a very long period of time (one million years, I think). In the story, the aliens don't force the humans to live through the event; it's a natural event, and the aliens are just along to observe.

2. Main character has an argument with his wife, which involved slapping her; but he is able to overcome that motion.

3. I don't remember the "ghost woman" part, I'm afraid, but it sounds like something Zahn would do.

The line "The Giftie Gie Us" comes from a Robert Burns poem, "To a Louse".