The Void is the philosophical concept of nothingness manifested. The notion of the Void is relevant to several realms of metaphysics. The Void is also prevalent in numerous facets of psychology, notably logotherapy.
The manifestation of nothingness is closely associated with the contemplation of emptiness, and with human attempts to identify and personify it. As such, the concept of the Void, and ideas similar to it, have a significant and historically evolving presence in artistic and creative expression, as well as in academic, scientific and philosophical debate surrounding the nature of the human condition.
In this sense, knowledge or experience of the Void could be said to actually be unknowing, given its inherent ineffability. In Western mystical traditions, it was often argued that the transcendent 'Ground of Being' could therefore be approached through aphairesis, a form of negation.
Western philosophers have discussed the existence and nature of void since Parmenides suggested it did not exist and used this to argue for the non-existence of change, motion, differentiation, among other things. In response to Parmenides, Democritus described the universe as only being composed of atoms and void.
Peter Matthiessen in The Snow Leopard (1978) described an experience of sitting on rocks in the Himalayas as leading to an awareness of a Void at the centre, or the source, of phenomenal existence: "These hard rocks instruct my bones in what my brain could never grasp in the Heart Sutra, that 'form is emptiness and emptiness is form' - the Void, the emptiness of blue-black space, contained in everything."
For Ken Wilber in Spectrum of Consciousness (1977), the Void is not mere nothingness, and is therefore distinct from something that can be subsumed into the category of nihilism, and is instead "reality before we slice it up into conceptualism". Here he explores the idea of nyat?, which cannot be "called void or not void; or both or neither" but can be referred to as 'the Void' with, again, the proviso that it exists beyond the limit of language.
Stanislav Grof's distinction between holotropic and hylotropic experience is important here, with the former encapsulating experiences which connect to the Void.
A similar line of argument is explored in The Void (2007) by Frank Close, who discusses the concept of 'empty space' from Aristotle through to Newton, Mach, Einstein and beyond (including the idea of an 'aether' and current examinations of the Higgs field).
Another perspective on the matter from a scientific angle is the work of the physicist Lawrence Krauss, particularly his 2012 book A Universe from Nothing, in which he explores the idea of the universe having been derived from a quantum vacuum (which may or may not be the same as a philosophical concept of the nothingness of the Void, depending on how it is defined). A further consideration is the enigmatic nature of dark energy which may be seen as coterminous with the Void. His work has received sustained criticism from David Albert and others working in both philosophy and physics.