The term 'Noumena' was a plural term for things that are in and of themselves, rather than just things that we perceive via our senses. The term was first popularised by philosopher Immanuel Kant in the Critique of Pure Reason, published in 1781. The singular term for 'Noumena' is 'noumenon'.
The term 'Noumena' is widely used today to refer to the apparently infinite processing environment in which we live. 'Noumena' is usually capitalised to represent the extreme importance of the concept. The term 'Noumena' should not be used to refer to the actual realities simulated within this processing environment; these are referred to as 'phenomena'. The singular term for 'phenomena' is 'phenomenon'.
The term 'phenomena' was also popularised by Immanuel Kant in the Critique of Pure Reason; he defined phenomena as being things that we perceive via our senses. This definition is the reason why 'phenomena' was chosen to define the simulated realities.
The singular term 'noumenon' is used to refer to the processing environment responsible for the simulation of one phenomenon.
The Noumena runs simulations using a system similar to lattice quantum chromodynamics. Lattice quantum chromodynamics is based on the theory of quantum chromodynamics, developed through the latter half of the twentieth century, and provides a way of perfectly simulating a volume of space-time by means of a simulated lattice of pixels following set mathematical rules. Lattice quantum chromodynamics demands a huge amount of computing power, and even the most powerful supercomputers at the turn of the twenty-first century could only simulate a volume of space-time smaller than an atomic nucleus. It is these taxing processing requirements that first allowed humanity to determine for sure that it exists within a reality simulation.
The origin of the Noumena or, indeed, the nature or construction of the computing systems that run the Noumena is completely unknown, as nobody has found a way to leave the Noumena, which are apparently a completely closed system. However, there are many theories to try to explain the origins of the Noumena in the 'real' world.
Some think that the Noumena are part of some sort of huge simulation computer built by a post-human civilization, designed to run ancestor simulations and universe simulations for research and perhaps entertainment. Proponents of this theory usually put forward a network of matrioshka brains or jupiter brains as the processing system that runs the Noumena, but there are many doubters of the idea, based on the fact that the Noumena have not proven to be finite (and therefore running on a finite computing system), and humans do not seem to posess any special position within the Noumena, which would be expected to be the case if the controlling covilization was post-human.
Others claim that there is no reason that the computing systems of the Noumena should exist in a universe with the same laws of physics as the Datum Phenomenon. They point out that a universe with a Planck distance, Bekenstein bound or Boltzmann constant that is very different from that of the Datum Phenomenon could fit a much larger computational capacity into a much smaller volume, to the point at which the Noumena would seem infinite, but are in fact extremely large but finite.
A different idea is proposed based on the works of Omega Point cosmologists such as Frank Tipler. They theorise that if an extremely advanced civilization were to transform their whole universe into computer supstrate, then trigger a Big Crunch (universal collapse), then diminishing distances of communication and an increasing vacuum energy-density would result in a continuous increase in processing capacity. Once their universe collapsed down to a point, it is claimed that the 'Omega Point' is reached, at which an infinite amount of computation spanning an infinite amount of subjective time can be performed within aero volume in a zero duration of subjective time.
Possibly the most widely accepted theory is that there are no creators or originators of the Noumena, and that thay have come about through random natural processes that emulate computing. Even if such processes were apparently random and chaotic, the work of renowned futurist Hans Moravec shows that an infinite number of finite simulations could take place in such a finite region; the conclusion would be that the previously clear line drawn between simulation and reality is, in fact, flawed, and that there is effectively no distinction. Though this seems the most likely theory for the origins of the Noumena, it is commonly accepted that we will never know for sure.
The Datum Phenomenon is our originating reality; it is simulated with a lattice resolution of 10-48 metres - smaller than Planck length. As far as we know, Earth is the only planet on which life evolved in the Datum Phenomenon; this is not surprising, considering Pierre Lecomte de Nouy's calculation in his 1947 book Human Destiny, which shows that the probability of a complex molecule conductive to the emergence of life forming in a primordial soup is effectively zero.
Given the scale of the Datum Phenomenon, it cannot be assumed that it was the intent of the creators (if there were creators at all) of the Datum Phenomenon that life would form. It is more likely that life evolved purely by chance in a phenomenon intended for some other purpose which cannot be confirmed.