A good theory, but I think you have slightly misinterpreted the findings of this particular research. This new model holds that, whilst travel into
the past is theoretically possible, doing so will render you unable to alter those specific events of which you have certain, definitive knowledge of
in the future. It does not mean that you will be intangible, it just means that if you know something to be true in the future, you will be unable to
alter that thing in the past.
To illustrate: say you really hated your boss and decided to travel back in time to kill him before he becomes your boss. After you travel back in
time to commit the deed, one of two things will be possible, according to this theory:
1) If, when you left the future, you knew for a fact that your boss was alive and well in the year 2005, you would be unable to subsequently kill him
in the year 1985 (or whatever year you had travelled back to). However ...
2) If, when you left 2005, you were uncertain as to whether your boss was alive or dead, then you may indeed be able to kill him in the past. Sound
crazy? Let me explain, because it is kind of crazy (that's quantum physics, after all).
First of all, this theory rejects the concept of parallel universes splitting off from one another based on the choices individuals make. The theory
argues that, since we do not see evidence of time travellers affecting the present (eg. people simply 'popping' out of existence), that the past
must be unchangeable to a certain extent. The theory then utilises the
uncertainty principle to explain why it is not possible to change certain
things in the past.
Basically, this principle states that, before you know something to be true, there exist a number of possibilities regarding its state. However, once
you know the truth, those possibilities shrink to one. Therefore, if you are unsure of whether something is true in the year 2005 (for example, you
are unsure as to whether your boss is alive or dead), you may be able to affect it in the past, since there are a number of possibilities regarding
it. However, if you know it to be true in the year 2005 (for example, you know it to be true that your boss is still alive), then you will be
prevented from affecting it in the past. In the article, they use the example of trying to kill your own father and state that:
If we don't know your father is alive right now - if there is only a 90% chance that he is alive right now, then there is a chance that you can go
back and kill him.
But if you know he is alive, there is no chance you can kill him.
You are still able to interact physically with the past but, according to the theory, you will be prevented from altering anything you know to be true
in the future:
You go back to kill your father, but you'd arrive after he'd left the room, you wouldn't find him, or you'd change your mind," said Professor
Greenberger.
You wouldn't be able to kill him because the very fact that he is alive today is going to conspire against you so that you'll never end up taking
that path leads you to killing him.
So you see, any 'ghosts' in this scenario would be quite solid, tangible human beings. They would simply be limited in their actions as a result of
quirky quantum laws.
I still like the essential core of your theory. I believe that there may be some merit to the concept of ghosts being a visible example of some kind
of overlap between different dimensions. How one would go about proving or disproving this, I have no idea.