Reality is fickle and impossible to prove. We all experience it in some form or another and do our best to connect all the variants. Minds across time and the planet have come up with very intriguing theory of the nature of our realities and unpercieved ones beyond our own. You will not agree with all of these supositions, but its fun to see what other people think and dream.
This theory describes the direction and final state of the universe. Developed in the early 1800's in Europe, it supposes that the is a finite amount of energy and once that energy is spent the universe will stop and freeze. There is nothing that can be done to create more energy so once that final molecule commits it's final vibrations the universe will be a dark, cold, silent place devoid of life. This definitely sounds very Victorian.
A philosophical theory expressing the view that, 'I am only the mind which exists'. According to this theory we can not verify anything outside of our minds. This includes every object you can see, the earth we reside on, even the idea of 'we'. Everything is potentially fictional. It easiest to relate this viewpoint to dreams or an LSD trip. Everything is so detailed so believable but we don't acknowledge those as a true reality. So once we come back to our 'base line' reality how do you differentiate with any real distinction what is 'real' or not.
This an old idea that we now view as a group of philosophies that span the globe. The general assertion is that the reality we can knowingly perceive is entirely a mental construction and entirely immaterial. A split in the philosophy occurs when deities enter the picture. The gods or god being omnipotent being focu and creation to our universe. On the flip side the universe is the sum of the minds of the sentients in the universe. Which side of the coin do you favor?
Plato and Logos
Plato was the famous Greek philosopher in the times of the roman empire. His understandings of the universe are still shared with the students of today. Logos refers to many schools of thought including the provability of the Judean christian God. We'll focus on Plato's version which our realm of experience everything we see is a compromise of its 'true' form and what we can understand and connect with. He surmised that there is a world of 'perfect' formations beyond our own.
This understanding relates to time and how humans naturally divide it. According to presentism anything beyond the moment we live in are imagined concepts. The past and future are not real. The meal you ate earlier and the words you are reading now will stop
existing until you come across it again. Time is central to to an occurrence and does not exist before or after the occurrence.
Presentism's opposite, this speculation states that time is 'multi layered'. All time exists simultaneously, but the ability to view events is dependent on the observer's location and where he is looking. According to this Trump and Gandhi exist simultaneously. Because all events are events in the universe you have already done everything you will ever do and are constantly revisiting everything you have ever done. This eliminates free will by its definition. How can you choose some different in the future if you're already committing the opposite action?
The Multiverse Theory
This is one of my favorite theories of the realities of the universe. It states that there are an infinite number of universes. In every one of the realities events happen differently. In a parallel universe you are a king among men, or you don't exist, or everyone is a saurian! I like this one the most because it is a blanket theory encompassing many theories for the difference in universes and the connections between them.
A branch of the multiverse theory that asserts that when we imagine something we bring into reality somewhere across time and space that imagined reality. So you write a little poem about a short man and big boat who has silly adventures. Well once imagined that person now exists in a world somewhere. There are varying thoughts on whether it must be written down or at least orally shared with someone for the creation to happen. Also there are split off theories that the more people view the characters or imagined world the more energy is put into the creation and separation process.
This theory explains the fallibility of object permanence. That is to say that when you stop viewing or interacting with an object it disappears until needed again. Philosophers supporting this believe that objects need awareness belief and perception to keep them in the physical world. Otherwise it becomes a memory.
source = http://thespiritscience.net/2016/01/28/9-theories-reality/