Quote from Aéius Cercle:
"See, this is why it's so difficult for people who are cemented & used to the idea that there must be «a beginning» or even «THE beginning» when in «reality» (beyond the physical from where the physical even «manifests» into existence) there are actually numerous & multiple-beginnings."
You are confusing the mental realm and the physical realms. What you say is true for the mental realm, but not for the physical realms, and the explanation is simple: The Law of Cause and Effect is the very idea that makes physicality possible.
So, in a physical realm (universe), time is linear, because it's part of the identity of the universe. It's not straight though, but revolves in spirals. If you stretched it, it would be a line – that's why we call it a time_line_.
Each timeline has a beginning. It begins when a previous timeline is splitted, or when a universe is created from the mental realm (which is essentially the same process). You even say it yourself: "...from where the physical even «manifests» into existence". This manifestation is the beginning.
Now, here's a very important question: Can you leave a universe, go back into the mental realm, and enter the same universe at a time before you left?
The answer is: No, because it would violate the law of that universe (the rules of that game). For example, imagine you're playing chess with another person, and the other person made a move you don't like. Can you take back the move of the other player? Of course the other player won't accept it. You can't disturb the progress of the other players, as it would violate free will.
But it's totally possible to make a copy of that universe and create your own game.
Now, how does the Mandela effect fit into the picture? As far as I'm concerned, it's totally possible that people remember a different universe. But it's not possible that someone changed an already existing timeline retroactively. A universe where the timeline can be changed that way is corrupt – or in other words: It's a game nobody wants to play because it's buggy. It would be like a chess game where the pawns can move like the queen – it wouldn't be chess anymore.
What I described here is called the Law of Identity, which is the foundation of Logic. Every universe is based on this simple law in order to have integrity, which is needed for cause and effect to create time.
Re: «Now, here's a very important question: Can you leave a universe, go back into the mental realm, and enter the same universe at a time before you left?»
It's actually been done before.
Read the reincarnation-research of Dr. Ian Stevenson in the 7th Chaptre of his book : «You Cannot Die : The Incredible Findings of a Century of Research on Death»
The spirits (beings/ISBEs), some of them, literally do «choose a time» when to incarnate/re-incarnate, some of them choosing «medieval-times» because, for some reason, they thought it would be fun, perhaps live those fantasy story lives found in fiction-books, only to find the reality that live in those conditions was actually every difficult, more like toiling 80h/week for survival.
Two objections:
1. How did he prove it?
2. How do you know that the ISBE chooses a life within the same universe?
Re: «that's why we call it a time_line_»
Geometry exists in more shapes than just lines; there are certainly time-lines, but, there are also time-loops, time-dilations, time-pockets, time-configurations, even time-waves, etc., although the «time-_line_» is certainly a «dominant» prevailing construct of this material-universe.
There are no time loops.
Time dilation is just a different perception of a timeline, as explained below.
Time pocket/configuration/wave: What does that even mean? Can you please explain how they differ from a timeline?
Re: 1
That takes a very long time of gathering a lot of pain-staking evidence.
Re: 2
For both questions just read this whole entire chaptre...
http://guild.quantum-note.com/m/book/isbn/0-416-00191-2/You-Cannot-Die-ISBN-0-416-00191-2-Chaptre-VII-Reincarnation.doc
I can't guarantee that it will «prove» anything to you, but, I guarantee you that you will get a lot of very useful information from it as to how the evidence was gathered (pain-stakingly), many instances of the evidence being gathered by «skeptics» who set out to literally «debunk» everything to do with re-incarnation, only to find that they ended up proving its existence to themselves and many others who familiarised themselves with the research-data.
For a copy from Amazon go to https://www.amazon.com/You-Cannot-Die-Incredible-Findings/dp/0458937509/ref=sr_1_1 or which-ever country which you may choose to order it from or ask a librarian at a library if they have a copy available.