P

erhaps you have read the above article. It is an overview of present theories about various many worlds hypothesis. Here it is proposed that there are four levels of other universe theories.

Level 1

This is the level of "parallel universes". They are parallel because they exist in the same overall space as us but haven't come into view yet. For instance, a section of the universe 10¹⁰⁰ light years away right now would be a parallel universe. It exists parallel to us but we can't see it ... too far away ... light hasn't reached us yet ... and perhaps may never reach us due to the rate that the universe expands. Hence, it is "another universe".

Level 2

These universes are of the baby bubble type created when space stretches. They are infinite spaces within our infinite space ... or something like Hawking's baby universes? (This is supposedly the domain of the P(pea)-branes ;o)

Level 3

This is the quantum "many worlds" hypothesis. Here, every time a "choice" is made ... the universe branches into multiple other universes in which all possibilities are played out.

A level 1 and 3 disagreement:
    from Sciam -
    Whenever observers are asked a question, make a snap decision and give an answer, quantum effects in their brains lead to a superposition of outcomes, such as "Continue reading the article" and "Put down the article." From the bird perspective, the act of making a decision causes a person to split into multiple copies: one who keeps on reading and one who doesn't. From their frog perspective, however, each of these alter egos is unaware of the others and notices the branching merely as a slight randomness: a certain probability of continuing to read or not.
    As strange as this may sound, the exact same situation occurs even in the Level I multiverse. You have evidently decided to keep on reading the article, but one of your alter egos in a distant galaxy put down the magazine after the first paragraph. The only difference between Level I and Level III is where your doppelgängers reside. In Level I they live elsewhere in good old three-dimensional space. In Level III they live on another quantum branch in infinite-dimensional Hilbert space. - Tegmark (sciam 05/03)

from EBTX -
The view expressed here is that there are only a finite number of possible universes (after you have established a given size and temperature of a section of the universe). So ... it must repeat itself (exactly) over and over albeit at incredible distances such that this hypothesis could never be verified. Then there would be multiple copies of yourself - and the Earth - wherein you do different things instead of what you actually did (meaning that one of your copies actually gets all the babes you only imagine).

I don't believe this is true. The "set A" we are currently experiencing may disallow a conceivable "set B". Hence, that branch would be contradictory. State A must go to state B by causal mechanisms for all events at the humanly observable level. This should rule out most (or perhaps all) other possibilities. Thus, I am saying that ... given the "set A" of the Earth in 1945 ... the conceivable event (set B) - Hitler Wins WWII - is a contradictory result. There may be many initial sets "A" (the initial universe) which result in a Hitler loss (set "B") following a 1945 which is substantially the same as what we actually experienced.

Also, though there may be a finite number of quantum states for a given volume of universe to be in (this too is debatable) ... some strings of events are absolutely incompatible. Thus, not everything conceivable can occur. If we allow that any "set B" may occur, we are left with the cubic planet anomaly (wherein there must be a finite probability that a planet size body will form up as a cube and remain that way in defiance of gravity) ... and ... the mass suicide anomaly (wherein there must be a finite probability that an entire planet's population commits suicide simultaneously for no reason) ... or how about a cubic planet on which everyone commits suicide?.

This is what Aristotle referred to as "babbling" in Sophistical Refutations (one of my all time favorite comedic documents). More accurately it is an inability to see determinism when one has fully focused on inderterminism as the sole driving mechanism of existence. Even though seemingly contradictory, both are present.

A speculation:
I believe that there may be a mathematical mechanism wherein probability is altered as the number of trials goes up ... something like the Law of Large Numbers where the probability that the number of heads or tails in coin flips will converge on 50% as the number of trials approaches infinity ... but applied to individual complex events. Thus, if the likelyhook of an event occuring in X number of trials is 25% ... then the probability of it occurring in 1000X trials may go down to, say, 2%. ... that is, past results influence present results, in direct violation of what is presently known about probability. But ... human behavior is like that ... non-random ... past results influence future behavior. Past history influences the behavior of present "matter" through the abstract information carrying capacity of human beings.

At this level ... anything goes.

A level 4 disagreement:
    "... all mathematical structures exist physically as well. Every mathematical structure corresponds to a parallel universe. The elements of this multiverse do not reside in the same space but exist outside of space and time." - Tegmark (sciam 05/03)

This is the explicit statement that physicists believe there exists a one to one correspondence between reality and mathematics. Hence, they need only find an equation derived from anywhere then imagine a physical situation that might correspond to it ... and ... that's enough ... discovery by fishing exclusively in mathematical waters.

My own view here is that this is a complete impossibility. Because the universe is the manifestation of the only logic there is, there can be only one universe. What we see is not the subject of logic. It is the thing itself. Hence, we may not take parts of it and make a viable universe. All of it goes at once ... and ... what you see is the result.

At the end of the article ... a laugher:

   "But an entire ensemble is often much simpler than one of its members ...

    In this sense, the higher-level multiverses are simpler. Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, |much simpler!| upgrading to Level II eliminates the need to specify physical constants, |simpler yet!| and the Level IV multiverse eliminates the need to specify anything at all." |Hey,. I'll buy that for a dollar!| - Tegmark (sciam 05/2003)

I'll go ya' one better, Max. No further need for science ...

That's even simpler by your criteria ... ;o)