Suppose we have an electron and a proton, floating in space, minding their own business. For the most part, they would continue in a straight line. The odds of their doing anything else are rather low. However, should they pass close to one another, this changes. The odds are high that the electron will throw off a photon, losing energy, but keep precisely enough energy to drop into an orbital and form a hydrogen atom.
Not news. Happens all the time.
But the photon is emitted before the electron interferes with itself for the first time. The energy level of the photon is precise enough that we know the electron is interfering with not just its first future orbit, but with many future orbits. If orbits are determined by single particle interference, this implies that cause can at times come before effect. The probability of an event that occurs at time T is altered by the possibility of things happening at time T+ (integer * period of the orbital).
We are about to leave the realm of subatomic particles, of photons, electrons and protons, and enter the largescale world of dice, coins and people. Before clicking next and returning to the every day observable universe, some time might be spent comparing and contrasting the common sense Newtonian world view with the paradoxical quantum reality, and perhaps develop further the concepts of Many World and temporal interfering reality. In what sort of weird universe might particles interfere with their future selves, and psi experiments work?
Quantum effects are visible, barely, in the every day world immediately accessible to the senses. Electrons moving between electron shells emit light at specific and well known energy levels. Analyzing the bands of light emitted by a material tells one much about the material. Semiconductors are also designed based on an understanding of quantum interactions and control of electron interactions. Still, these effects are subtle. If one doesn't need to analyze a material or design a semiconductor, one can live one's everyday life in ignorance of quantum effects. For practical purposes, living in Newton's causal word view is still a valid option.
Psi is an equally subtle effect. There is a probability shift, though a small one. As probability is an artifact of quantum reality, rather than Newtonian reality, looking for a quantum explanation of psi is reasonable.
Newton's reality is analog. One deals with shades of gray, with fractions, with soft smooth curves that flow into one another. Quantum reality is, well, quantized. It is digital. Newtonian objects are unique. No matter how hard one strives, no two objects can be precisely identical. Quantum objects, particles, are inherently identical. They are described by integer state variables. Properties with fanciful and poorly understandable properties like spin, beauty, and charm, are given firm numbers which might be 1 or zero or occasionally 1/2, but are never 3.6453. One doesn't find a smooth range of particles falling along a bell curve. One moves starkly from one well defined and precise state to another quite distinct state, zero chance of observing any form of gray in between.
Why are quantum events quantized? Is reality ultimately Newtonian analog or quantum digital? How is it that the analog behavior of larger objects breaks down at quantum levels but not before?
Interference. Quantum level objects are positively interfering with each other, or themselves. A few specific configurations self reinforce each other as standing wave patterns. It is highly probable that these configurations will be observed. Other configurations, the gray in between states, might be in some sense possible, but they do not positively self interfere.
The chance of observing an electron orbiting an atom at energy levels different from the selfinterfering energies is zero. There are many energy levels at which electromagnetic forces could curve an electron into a cyclical orbit, but only if the period of the orbit is a multiple of the period of the electron might the electron be observed. Similarly, there are an infinite variety of particles with properties like spin, beauty and charm in noninteger amounts. Perhaps as these particles don't self interfere, the probability of observing them is slim to none? The universe is in one sense analog. The analog rules observed in the mundane Newtonian real world still apply at smaller scales. However, lack of selfinterference makes most analog behaviors not truly impossible, but they have a zero chance of being observed none the less.
This might be interpreted as a quantum level manifestation of the psi force, a force which doesn't move particles as explicitly as electricity, gravity or magnetism, but which none the less guides particles into specific configurations that self reinforce. The universe resonates. Configurations that fit certain flows and patterns are probable, while other patterns cancel themselves out, can never occur. It is not sufficient that a particle exist here and now, and in a few other alternate nows. The particle must also have reality in the pasts and/or futures, and in many alternate parallel realities.
An overly simplistic first impression of this resonance can be seen in single particle interference and electron orbitals. If there are many ways for a particle to reach the same place in the same phase at the same time  or an integer multiple of the particle's period later or earlier  there is a high probability of observing the particle there. This reflects the beginnings of reverse time causality, of temporal selfinterference. A particle is apt to be observed somewhere at time T if there is one or more probabilities it might return there at time T+IP, where P is the period of the particle, and I is an integer.
Extending this principle, one might reinterpret the uncertainty principle. Under the Copenhagen Convention, it is understood that one might never completely know everything about a particle. The more precisely one measure some of its properties, the less one can know about others.
Under a psionic variation of Many Worlds, this might be restated. One can never directly observe a single manifestation of a particle. One never observes just one of the Many Worlds. One is actually observing a group of selfinterfering alternate versions of the particle, particles representing very nearly identical alternate realities, realities which differ only plus or minus a fudge factor corresponding to the uncertainty principle. One might not view the uncertainty principle as a fundamental limitation on measurement, but as a window limiting the number of alternate realities that can be concurrently observed.
In making any such observation  in looking at a set of manifestations of a particle  one is causing a collapse, is forking off alternate realities. Observing through the a window into one set of Many Worlds alternate realities voids the possibility of observing any of the many other possible sets of alternate possibilities.
(Next) Moving from quantum reality to psi.

Many Worlds  Single
Particle Interference  Orbitals 