Mystics claim, whatever we experience as our reality, is depending very much on the experiencer. And indeed, if we take the mystical approach and look, who is experiencing, we cannot come to an unambiguous conclusion. It’s impossible to define clearly with words, who we are. What we can do, however, is to exclude, what we are not, for example by stating
“You are never, what you think you are, and reality is never, what you think it is.”

Why? Because any thought that appears on our inner screen is a representation of a phenomenon or a group of phenomena of your sensual impressions and not the phenomenon or the group of phenomena itself. The mind never deals with the world out there directly, it is identifying and naming objects and thus creating internal symbols, words and sentences from the impressions it receives through the senses. The objectivity of our world is imaginary as we are only dealing with interrelating symbols within ourselves, which are forming thoughts and emotions, which are transformed into chains of thought in our brains. These processes are happening so fast, that we usually don’t realize their complexity and consequently we also fail to notice that each perceiver has his own unique version of an object.
The ancient yogis and rishis of the East understood the deceptive illusionary character of the world of phenomena through self observation and created the terms maya or samsara for the fleeting world of material and virtual objects.
In natural sciences on the other hand, we took the world as fairly static, solid and objectively real for many centuries . But since Einstein, Heisenberg, Bohr and the development of quantum physics the scientists and mystics have been coming very close to each other. Here are a few examples from the world of science, to make it clear, that there is also no absolute truth in science:

1. P.D. Ouspensky, a Russian mathematician and theosophist, who worked with George Gurdjieff, is giving a nice example from the field of mathematics:
Anybody will agree that 1+1=2, right? If you, however, allow infinite as a value, you can make an equation ∞+1=∞, because infinite is always infinite, whether you add something or take something away. Then you take ∞ on both sides away and you’re left with 1=0 and the whole system comes crumbling down! That’s why the mathematicians have to exclude infinite and zero for certain operations, because math will not work otherwise. Which means, however, that mathematics is only true within a certain defined range and not absolutely, universally and indefinitely. When we look into realms beyond the mind the defined range is not valid any longer. Even Stephen Hawking, a famous contemporary genius of physics, admits in one of his books, that all of our scientific statements are not THE truth, but only auxiliary devices, as long as they give us a reasonable explanation and allow certain predictions about a phenomenon. Therefor there cannot be a guarantee that a formula, which works today, will also work tomorrow.
George Lakoff, one of the leading linguists of the last fifty years, comes to similar conclusions in his studies: “Mathematics turns out not to be a disembodied, literal, objective feature of the universe but rather an embodied, largely metaphorical, stable intellectual edifice constructed by human beings with human brains living in our physical world.” (Metaphors We Live By. 2003)

2. For a long time people believed in the flatness of the earth. Most of us laugh about it today, but for 15th century European citizens it was an experiential truth, that our planet is level like the surface of a frozen lake. Spheres were not rolling down to the left or right, when placed on the ice or an even board and generally in their own lives the concept of a flat earth worked perfectly well. So in fact the idea of the world as a sphere would have sounded rather weird to them. After Columbus, Kopernikus, Galilei and Newton the official views changed (after some trouble with the churches) and anybody, who still believed in a flat earth, was regarded as ignorant, even though from the perspective of the normal citizens nothing had changed. Even in our present day lives we are still partially thinking in terms of a geocentric plain, i.e. when we are using the words “sunrise” or “sunset” we are talking as if the sun would be circling around our planet, and architects are planning our houses on flat grounds as if the world would be flat. Also most distances are still calculated in a two dimensional flat surface model. Meanwhile Newton’s gravitational laws have been proven inaccurate to some extent by Einstein and his formulas are regarded as the real laws of physics. But one day somebody else will find even better equations …So, it is clear, we don’t have absolute values in science and all in all we can say that instead of looking at “true or untrue” we are dealing with a variety of concepts. Some of them allow us better predictions and others are allowing not so good predictions. 

3. The coastline paradox: The measured length of the coastline of an island depends on the accuracy of the method, which we use to measure it. Since a landmass has features at all scales, from hundreds of kilometers in size to tiny fractions of a millimeter and below, there is no obvious size of the smallest feature that should be measured around, and hence no single well-defined perimeter to the landmass. For example the coastline of England can be measured from a satellite view (1), from an airplane view (2) or from actually observing the coast (3). Obviously we will have a problem with the last method as the level, frequency and power of the incoming waves are changing constantly. Various approximations exist when specific assumptions are made about minimum feature size.
(excerpts from Wikipedia, full article see here: the coastline paradox)
If we are given the task of measuring such an object, we have to decide, which method is appropriate for our purpose. In case we want to make a bicycle trip along the coast of the main British island, we will probably not measure each stone on the shore, but rather we will measure the length of the roads in the vicinity of the coastline. The difficulty of multiple solutions arises not only in regard to the coastline of an island, but to many objects and processes in our world. In order to preselect from the infinite options, which we are facing in every moment of our lives, we are developing certain structures, routines and beliefs, which in turn influence our perception of reality.

Modern science confirms the view of the mystics, that we create our reality through our means of perception individually and subjectively. There might be a big overlap between your reality and your friends reality, and all societal groups have certain reality overlaps within their members, but ultimately your reality is unique. Each sentient being, each reflector of existence operates within their own reality and their own universe. If you take in account additionally that each being creates a new universe every moment (again with large overlaps from the universe of the moment before, but still fresh and new), it is not surprising that there is big chaos everywhere. In fact it is truly amazing that anything works at all! Yet, for reasons unknown, extremely unlikely and complex phenomena are continuously appearing (and disappearing) on our planet. And we actually have no chance to find out, why it’s all happening, as in the process of observation reality is already changing and being recreated. All we can say, is, that there is a something, a vague potentiality, an energy flow, which becomes a temporary actuality through being observed.