Per 
Item #: SCP-XXXX
Object Class: Safe
Special Containment Procedures: SCP-XXXX is to remain in Vault-12, and should not be entered without approval from the current site director.
Description: SCP-XXXX is a wooden door. Upon stepping through SCP-XXXX, an individual becomes superposed between an unknown amount of realities. Said individual will remain in this state until someone checks which reality they are in, destroying the other realities in the process.
A better explanation of this anomalous effect can be seen in the "Schrodinger Cat" thought experiment. If a cat is in a box, an outside observer would be unable to know if said cat was dead or alive without opening the box. As such, until the box is opened the cat is both dead and alive. This special state of being collapses upon opening the box, wherein the cat is either dead or alive.
Similar to how the cat can be both dead and alive, subjects who enter SCP-XXXX exist in multiple realities at once. Furthermore, like said cat, a subject inside of SCP-XXXX will only exist in one of those realities when someone checks their location. This can occur by communicating with said individual, or by reading transcripts of past conversations.
Addendum 1:
The following is an experiment log recorded by Researcher Grey. It should be noted that this experiment was originally supposed to be performed by Dr. ███████, while Ms. Grey observed and helped when necessary. However, due to a last minute familial issue, Dr. ███████ was unable to perform this experiment, and authorized Ms. Grey to perform it in his place.
Ms. Grey: D-3903, can you hear me? I repeat, D-3903, can you hear me?
D-3903: Yeah, I can hear you. I appear to be in some sort of market, although I can't see anyone. I also can't see the door.
Ms. Grey: Understood. Feel free to wander the market, let me know if you see anything interesting.
D-3903: Sure thing.
D-3903: One of the market stands has a stack of blue watermelons. Permission to try one?
Ms. Grey: Permission denied. We don't know whether or not those watermelons are edible.
D-3903: Understood.
D-3903: There is another stand, this time it has a sword and a compass. Permission to take one? They could be useful.
Ms. Grey: Sure.
D-3903: I will take the sword… | I will take the compass…
D-3903: I will take the compass. It seems to be moving in erratic circles.
Ms. Grey: Understood.
D-3903: That's odd, as soon as I picked it up it started pointing towards a side road. Permission to follow the compass?
Ms. Grey: Permission granted.
D-3903: Understood. The side road is narrow and surround by buildings on either side. The compass seems to be pointing towards the end of this path. By the way, I was curious about something.
Ms. Grey: Can you please elaborate? What are you curious about?
DR. RAM
D-3903: I heard a noise from a building, should I investigate? |The compass is pointing down the street, should I follow it? I can see the end of the road…
D-3903: I heard a noise from a building. Should I investigate it?
Ms. Grey: What did the noise sound like?
D-3903: It sounded familiar… Like a voice I've heard before.
Ms. Grey: Can you please elaborate?
D-3903: It sounded like a muffled women's voice. I heard it again, but it seems like she is farther away. Please let me try and find her… I can't explain it, but I know that voice.
Ms. Grey: Permission denied. I think that voice is playing a mind game with you. It's calle-
D-3903: She's in danger. I need to save her. Please let me help her… I need to find her… I can save her.
The sound of a door opening can be heard as D-3903 presumably enters the building where he heard the voice
D-3903: There is a basement. The voice has to be in the basement… I just know it.
Ms. Grey: D-3903, please proceed with caution.
The sound of footsteps echoing can be heard
D-3903: Can I tell you something?
Ms. Grey: What?
STORY OF WIFE - MIGHT BE LAST PERSON I HAVE CHANCE TO CONVINCE
REACH BOTTOM
ENTER, CANT LEAVE
VOICE TORMENTING HIM, WHATEVER YOU DO DON'T ENTER THE DOOR
