For example, we ask questions like: Why is there something rather than nothing? it implies that we know the characteristics of what constitutes nothing and something. What if what we perceive as something are the characteristics of nothing, and therefore we don't exist?
Why do we assume that we know there is a difference between something and nothing?
The question "why is there something rather than nothing?" is so old and recurrent, which I think we do not know what it is "nothing" and "existence of the world".
Why is there something rather than nothing?
If nothingness means nonexistence, this is an illogical nonsense question because impose an impossible explanatory demand, to deduce the existence of something without using any existential premises. Since there can be no piece of reality that makes a statement true for an empty world, there is an objection to an empty world. A world is a totality of facts, a factless world is a contradiction in terms.
Why are there any contingent truths? What is the reason of the principle of sufficient reason?
The principle of sufficient reason states that nothing is without reason, but why are there any contingent truths? On the one hand, contingent truths cannot be explained by any contingent truth because the explanation would be circular. On the other hand, contingents truths cannot be explained by a necessary truth because a necessary truth can only imply other necessary truths, not contingent truths. Therefore the principle of sufficient reason impose an impossible explanatory demand, explain the existence of contingent truths without using either contingent or necessary truths. The principle of sufficient reason is absurd. The existence of anything could be proved by reason alone. We might still be able explain the existence of each event even if it is illogical nonsense to try to explain everything all together and to answer the question "Why is there something rather than nothing?"
What is nothingness?
The absolute physical nothingness, in the sense of void, the absolute vacuum, is impossible. Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the black body photons. Vacuum contains vacuum fluctuations, virtual particles that hop into and out of existence, and a finite energy called vacuum energy. To say that vacuums have energy and energy is convertible into mass, is to deny that vacuum is empty. Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. This can answer the question of why there is something rather than nothing. Why is there now something (particles) rather than nothing (energy in a quantum field)? Indian philosophers associate nothingness with lack of differentiation. The basic idea goes back to an issue raised by the symmetry of matter and anti-matter. Given that the symmetry implies equality, matter and anti-matter should have annihilated each other. But a small random change could trigger a phase transition, a slight numeric imbalance that biases the universe toward states in which there are many particles.
What is the existence of the “world”?
Our direct knowledge of the universe is confined to a limited region of space and time. In order to obtain some idea of the universe as a whole we must extrapolate and construct a world-model which will reproduce satisfactorily the principal features of the observable region. Therefore when a scientific realist looks at cosmology, no reason of principle dictates that its models taken as whole structures must stand for the "world" as a whole. There is no reason of principle for the scientific realist to say that cosmology implies that there is such a thing as the whole "world". Success could consist in every real physical system being adequately represented in a model, without there being a single physical system which is composed by all the others. We cannot simply go and check to see whether other possible "worlds” are real. There is no single thing which it denotes all dictionary occurrences of "world”. The term is context-dependent. For each occurrence of "world" in dictionary we identify some plausible region, system, or set of entities which delimits the statement's domain of discourse. In other words, we treat the general and unqualified use of "world" as schematic only, relying on contextual factors to turn the schema into a statement. We should not pretend that we have specified all uses of them. There are things that exist mind-independently but no entity as the collection of all things that exist mind-independently, the “world”.
Are things illusory? What is the “world” stuff?
If there are no objects which have the persistence conditions that we think, then there are no non-fundamental stuffs. But the very same arguments given for rejecting ordinary objects, like water, and reducing it for water molecules, can be given for water molecules. If there are in fact gluons and electrons which exist, are objects, and are particular things with identity and persistence conditions, then, if they are in fact simple, they form the basis out of which we could construct the other objects. But if so, and non-individual “world” stuff is going to play a fundamental role, it seems that we must eliminate fundamental particles as well. Some argue that both ordinary macroscopic objects and putative fundamental particles are only epiphenomenal manifestations in the electromagnetic or gravitational fields, which are fundamentally non-individual, some kind of “world” stuff. But the "everything theory" of fundamental physics, to tie all the known forces into a unity does not yet exist, monism is a hope. Why is there space-time? Answers to any riddles about space-time reduce to facts about objects. If there were no objects, there would be no space-time. One can wonder why there is space-time, but this is only to wonder why there are objects.
“The creation of the universe itself makes no sense. Time didn't exist before the big bang, so there is no time for to make the universe in. It’s like asking directions to the edge of the earth; The earth is a sphere; it doesn't have an edge; so looking for it is a futile exercise. If the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end.” (Stephen Hawking).
From Wikipedia, Stanford Encyclopedia of Philosophy, van Fraassen, van Inwagen.
Nothing is very difficult to conceptualise - we only approach it by analogy. It was first thought at least since Epicurus wrote on atoms that if air or matter is removed we have a vacuum and a nothingness. After the discovery of quantum field theory it was realised that vacuum itself is (very unlikely) to be empty. At around the same time Einstein discovered that spacetime is a thing. To truly have nothing one has to remove the whole of spacetime. But one can speculate that actually all this means is that our causally connected world disappears - something may still be left over.
Similar thoughts have been expressed by theological speculation - Christian and Islamic. Kant referred to a when the world was not as a place of nothingness in one of his antinomies, I expect this argument has a history probably back to Aquinas. The Ash'arite school of theology inspired by Greek atomism declared that spacetime was atomic. That is they realised that spacetime was a thing too.
Although, it has been said by Hawking and others that outside our world there is nothing. This cannot be accurate - empirically we can never know. There could be or there could not be. This is the space within which philosophical & theological speculation works - as one has no other forms of knowledge. As it is not empirically based there can never be objective agreement on their speculations - one decides for oneself. For example in certain schools of Indian philosophy time is cyclical - the world is destroyed and then remade, in the tradition inspired by the Upanishads there is not nothing as Brahman is the ground for all. In Spinoza extension & mind are just two modes of God, so the world is immanent in God. In materialism or atheism, as promoted by Dawkins amongst others the world itself is all that there is.
What if what we perceive as something are the characteristics of nothing, and therefore we don't exist
You can turn this back on its head - and say that since nothing has the characteristics of something then nothing is a thing too. More accurately one has to ask what can it mean for nothing to have characteristics? It appears only in a negative way, that it has none. Whereas as things has a characteristics in a positive way.
In Buddhism philosophy the idea of nothingness is central. Unfortunately I don't know enough to say anything about that. But, apparently Nagarjuna a Buddhist Philosopher said that the essence of something is that it has no essence.