I am planning a short story set in modern times where the protagonist has a ghost encounter but is not believed when reporting it to others. Produce a list of plausible justifications explaining how ghosts could have existed in this world without their existence becoming common knowledge, and describe potential plot ramifications associated with each one.
Here are some plausible justifications for how ghosts could exist in the world without their existence becoming common knowledge:

1.    Ghosts may exist in alternate dimensions or realities, meaning that they are hidden from the view of the average person. Plot ramifications associated with this could include the protagonist discovering a way to access these alternate dimensions and having to find their way back to the real world.

2.    Ghosts may be bound to a certain location, meaning that only those in close proximity can see them. Plot ramifications associated with this could include the protagonist having to travel to a certain location in order to encounter the ghost and being unable to prove the existence of the ghost to those not in the vicinity.

3.    Ghosts may only be visible or audible to certain people, meaning that only a select few can experience them. Plot ramifications associated with this could include the protagonist attempting to find others who can see or hear the ghost, so that they can provide evidence of its existence.

4.    Ghosts may only be visible or audible during certain times of the day or year, meaning that they can only be experienced during those specific moments. Plot ramifications associated with this could include the protagonist having to figure out when the ghost will appear and trying to convince others that the ghost is real during their brief window of visibility.
What are some places where I could set the story?
Here are some locations that could serve as a fitting backdrop for your ghost story:

1. An old, deserted house or mansion that is said to be haunted. This location could provide an eerie and creepy atmosphere while also serving as a classic setting for a ghost story.
2. A historical site or memorial, such as a castle or battlefield. This location may provide a rich historical context, allowing the ghost to be associated with a specific event or person from the past.
3. A secluded forest or park where the protagonist could experience the ghost away from modern life's distractions. This setting may provide a sense of isolation and unease while also allowing for exploration of the natural world and its potential mysteries.
4. A busy city street or public place where the protagonist encounters the ghost in the midst of daily life. This setting could serve as a contrast between the mundane and the supernatural, as well as highlight the protagonist's struggle to be believed.
5. An old, run-down hospital or mental institution, where the protagonist may run into the ghost of a former patient or staff member. This setting could evoke feelings of dread and foreboding while also allowing for an exploration of the darker aspects of the medical profession.