well... taken from wiki and once we put them together...
* quantum indeterminacy, state of a system does not determine a unique collection of values for all its measurable properties.
* indeterminacy due to chaos as described in chaos theory ("Sensitive dependence on initial conditions").
* indeterminacy caused by limited powers of observation and integration of the facts.
* limitations due to the nature of human memory and thought processes.
and then summing up with S.Hawking's own conclusion...
"These quantum theories are deterministic in the sense that they give laws for the evolution of the wave with time. Thus if one knows the wave at one time, one can calculate it at any other time. The unpredictable, random element comes in only when we try to interpret the wave in terms of the positions and velocities of particles. But maybe this is our mistake: maybe there are no positions and velocities, but only waves. It is just that we try to fit the waves to our preconceived ideas of positions and velocities. The resulting mismatch is the cause of the apparent unpredictability."
We would have in conclusion that the existence of everything is just like how we define existence of self using "I think, therefore I am". Some physicists are going into the protoscience with this by putting quantum mechanics into the study of human mind and subsequently using the idea of curved space and folded space (roll several dimentions into a wee dot) to explain conscience and the strange nature between wave and matter over the macroscopic world.
...and theoratical physic becomes philosophy.
Another interesting explaination to why is it we human typically are dull and are square, thus failing to see quantum indeterminacy in a universe where the interminacy laps on top of one another going from microscopic to macroscopic. (von Neumann's crisis)
* Wigner's friend resolves the inconsistency by asserting that human consciousness not only measures the physical world, but physically changes it from an indeterminate state to an absolute environment. This is known as the Consciousness causes collapse theory. <- Esse est Percipi, to be is to be perceived!
* According to the Copenhagen interpretation, humans created the quantum state vector because it was the only known way to describe the subatomic world mathematically, but there is no catastrophe because quantum mechanics doesn't exist in any real sense.
* The Many-worlds interpretation asserts that humans don't notice the indeterminate state of the universe because all possibilities but the one we observe happen in other dimensions that are beyond our ability to directly monitor.
* The Bohm interpretation avoids catastrophe and allows for determinism without splitting the universe into many worlds by asserting that the positions of particles are fixed by latent variables that are definite in cause and effect, but which can only be calculated in terms of probability by humans. (Like how that we don't know the exact formula for drop rate in MMORPG but we do know of the probability for drops)
* The Transactional interpretation allows for only one measurement while also permitting the existence of the entire wavefunction by requiring that the observer only detect the part of the source wave that phases positively with his own advanced wave. (We filter anything else as just noise... or we can't 'see' it)
Now we're finally heading back to the story premise of Haruhi
I am moving this to speculation since... it's time to make a guess at the story.