Provoked by a comment by Steve Mangiameli.
In my short story series, Penniless Joe is a down on his luck archaeologist/(al?)chemist that is struggling to get employment.
One day he goes to a pawn shop sell some stuff. The pawn shop owner convinces him to buy some weird liquor bottle he found. Joe is intrigued by the ceramic vial, with some uncommon characters he barely recognizes. He buys it for $1.99 and takes it home to decipher it.
He finds out that it is a "Groundhog day potion" that supposedly allows one to re-live one single day.
Joe decides to use the potion to get out of his wealth predicament. His choice is to win the state lottery.
Unknown to him, he made a mistake translating the inscriptions on the potion, and become a permanent "groundhogger".
The rules so far are:
- A groundhogger re-lives each day from 3 to 5 times before moving on to the next day. The amount of repetitions is random and cannot be predicted.
- A "repeat day" is day that will be erased and repeated. Days 1 and 2 of a cycle are always a "repeat day", day 3 is a repeat day ~33% of the time, and so on.
- The "last day" or "real day" is the day where "tomorrow" is "calendar tomorrow".
- If a groundhogger stays awake until midnight of a repeat day, everything goes black exactly at midnight, and the day begins anew at his first conscious moment of that day.
- If a groundhogger stays awake until midnight of a last day, he does not black out, and tomorrow's repeat days begin exactly at midnight.
- Anything that happens on a repeat day has no permanent effect. He just wakes up again next(this) morning. Just like Bill Murray's, even death is not permanent. He just awakes again this morning (to his subjective perception, immediately after losing consciousness and dying).
- That includes internal body changes, like catching a disease or impregnation (for a female groundhogger).
- Physical fatigue/wounds are completely erased. Mental fatigue is relieved completely if he wakes up from sleep. but only partially if he stays awake overnight. For that reason, they prefer to sleep.
- Since days 1 and 2 are always repeat, they are more daring on these days.
- He probably becomes permanently dead if he dies on a "last day". But he did not try that so it is unknown.
- He is not bound to a specific location. So he can travel to Vegas on a "last day" and wake up in Vegas tomorrow.
- He retains full knowledge/memories of what happened in the repeat days, to the limit of his own cognitive capabilities. No physical objects (paper notes, files on a USB drive, etc) are retained or changed on a repeat day.
Later on he finds other groundhoggers. It is dead easy to spot one when you meet him, because it is the only thing that changes on repeat days.
So on the interaction between groundhoggers:
- Both groundhoggers freely and independently retain memories of repeat days.
- Both of them can act on their own free will and do whatever they want on repeat days. Even avoid/escape meeting the other guy again.
- If a groundhogger is killed by another groundhogger on a repeat daynote1, the dead one awakes next morning (to his subjective perception, immediately).
- If a groundhogger kills another one in a last day, the effect is unknown. Probably permanent, but nobody tried.
- There is no compulsion over groundhoggers (no, there can be more than one) to act or interact with each other. There may be curiosity or kinship, but most avoid each other out of fear.
- Even on repeat days, the actions of one groundhogger can cause changes on the environment of another (thus causing the repeat days not to be equal). This (things not happening exactly the same way) is usually the tip to the presence of another groundhogger.
- It is unknown if all of them experience the same amount of repeat days for each day.
Given the rules above that already fleshed out on the written stories (and considered canon), what is the best explanation to how it works? I thought of some:
- Physical Time travel: groundhoggers do travel back in time. This does not explain how their bodies are repaired/recovered.
- Subjective space/precognition: they aren't actually repeating the days. They gain a very precise precognition ability, and are only mentally re-living that in their minds. This does little to explain how groundhoggers can interact with each other independently.
- Mental Time travel: groundhoggers send their consciousness back in time. This has the problem of explaining how their consciounsness are replaced.
- Alternate dimensions: each repeat day happens in an alternate dimension. This burns even more handwavium than the first one, above.
The list above is not meant to be exhaustive. Other explanations might exist.
So, what explanation to the effect described above requires the least handwaving, what its pros and cons, and where does it fall short?
- They know days 1 and 2 are always repeat. So they can be rather daring and open to experiments on these days.