Infinite loop theory

Infinite loop theory theorises the universe operates in a type of closed-loop event in order to avoid contradicting the second law of thermodynamics, which proposes all energy eventually has to run out, and thus would contradict the suddenly appearing big bang (or the big bang the second law of thermodynamics).

Theory origin
The theory originated when the big bang theory (the sudden appearance of a large amount of energy from nowhere) was observed to contradict the second law of thermodynamics (that energy decays over time and cannot appear spontaneously).

Although quantum physics state energy can appear anywhere spontaneously given a set of probabilities, it's not sufficient to counteract constant decay rate over time, and thus a theory for solving the problem of the supposed one-way energy decay conversion was required.

Theory details
As noted with Einstein's observations that energy eventually decays into matter, it was theorised that all matter, emitting mass (of which gravity has supposedly infinite reach regardless of how trivial), would eventually draw back to itself once all energy had finalised conversion from energy to matter and therefore mass and gravity.

The result would be a contraction-based implosion resulting in an expansion-based explosion (a variant of the big bang) and thereby generating a stable infinite loop sufficient to solve the contradiction of the origin of the in-universe energy. It's worth noting that such a system does not exclude the possibility of God, and only supplies a theoretical mechanism for internal universe energy stability.

The infinite loop theory is an example of an in-universe closed-timelike curve.

Single infinite loop:
Single infinite loop is basically that the contraction-expansion loop always produces the same result every time it expands and contracts. This could be considered a truly closed-loop as nothing can ever stop the system from looping as it never changes.

Multi-infinite loop
Multi-infinite loop suggests that it changes with every loop, for good and bad, and could be considered akin to multi-universe theory, although multi-universe theory suggests that the universes are running parallel (parallel worlds), side-by-side, at roughly the same time, multi-infinite loop implies it's one universe after the other and thus not parallel but consecutive. This might be considered a variation of the many-worlds interpretation.

In terms of lateral reincarnation
The theory basically suggests you will always return as yourself always doing the things you have previously done assuming an immutable (unchangeable) closed-loop system. There are however two variations of the infinite loop theory in regards to lateral reincarnation: single infinite loop and multi infinite loop.

Single infinite loop
Single infinite loop suggests the persons actions never change, never improve, never get any worse and they will always experience the same thing, noting parallels with eternity. However this system is considered flawed as the system never revises towards positive improvement (which should be the goal of any system tending towards energy efficiency and improvement).

Multi infinite loop
Multi infinite loop suggest the persons actions can change, and thus either improve or get worse. Assuming memories of previous iterations survive (see deja vu, fragments of memory , temporal distortions and iteration), it would trend upwards towards improvement (roughly) as previous mistakes are learned from. This forms the basis for the theory matrix of perfection.

Related
The inter-universe machine is a theoretical idea for a machine capable of travelling between multi-infinite loop universes. The machine will not work in single infinite loop universes. Iterations are based on multi-infinite loop theory in that each iteration occurs in a different multiverse.