Per 
SCP-XXXX
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 Junior 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.
Note from Dr. Grey:
I am so excited! My first SCP! I cant wait!
Date: September 8, 20██
Time: 6:38 PM
Procedure:
D-3903 was given a portable communication device, and was instructed to enter SCP-XXXX. Below is a recorded transcript of said device.
D-3903: Fine, I see a tree. I ginormous tree. It must be at least 30, maybe even 40 meters wide, and at least twice as tall as a skyscraper.
Dr. Grey: And around the tree?
D-3903: Nothing. Well, not nothing, just grass. All I can see is a grassy plain and a giant tree. I have no idea where the door went.
Dr. Grey: Would it be possible for you to climb this tree?
D-3903: Sure. Not to brag or anything, but I used to be pretty good at climbin' trees back in my day.
Dr. Grey: Uh huh, sure.
The next 21 minutes are filled with the sound of grunting from D-3903 as he presumably climbs the tree
D-3903: Okay, I have reached a branch.
Dr. Grey: That's excellent! Co-
D-3903: Give me a sec, my legs aren't what they used to be.
Around 7 minutes of heavy breathing and panting from D-3903 can be heard
D-3903: What were you saying?
Dr. Grey: Can you describe your surroundings?
D-3903: Sure, sure. I'm on a branch that is way bigger than me, and when I look up all I see are leaves and wood, and… That's odd… I didn't notice before, but nestled in the leaves of the branch I am on is a door. It looks similar to the door I just stepped through a few moments ago.
Dr. Grey: Can you please enter the door, and tell me what you see upon entering said door?
D-3903: Sure thing.
D-3903: I see a waterfall... | I see a red carpet...
