هیچ مفهومی است که نیستی هر چیزی را به کلی شرح میدهد. هیچ معمولاً همراه اسم و با فعل منفی برای سلب ویژگی یا حکمی از کلیه اعضای یک مجموعه یا جنس بهکار میرود. هیچ همچنین به معنی نیست و نابود و نیز فاقد ارزش و اعتبار است.
در ادبیات فارسی، اصطلاحات گوناگونی با ترکیب دیگر واژهها با هیچ ساخته میشوند:
هیچ در هنر و فلسفه[ویرایش]
هیچ در هنر، همیشه به معنای نیستی، تباهی و پوچی نیست، بلکه گاهی نمادی از عطش و تمنا بهشمار میرود. پرویز تناولی مجسمهساز مشهور ایرانی، آثار متعددی را با بهکارگیری شکل فارسی واژه «هیچ» خلق کردهاست. در
پیوند به بیرون[ویرایش]
"Nothing", used as a pronoun subject, is the absence of a something or particular thing that one might expect or desire to be present ("We found nothing", "Nothing was there") or the inactivity of a thing or things that are usually or could be active ("Nothing moved", "Nothing happened"). As a predicate or complement "nothing" is the absence of meaning, value, worth, relevance, standing, or significance ("It is a tale/ Told by an idiot, full of sound and fury,/ Signifying nothing"; "The affair meant nothing"; "I'm nothing in their eyes"). "Nothingness" is a philosophical term for the general state of nonexistence, sometimes reified as a domain or dimension into which things pass when they cease to exist or out of which they may come to exist, e.g., God is understood to have created the universe ex nihilo, "out of nothing".
Some would consider the study of "nothing" to be foolish. A typical response of this type is voiced by Giacomo Casanova (1725–1798) in conversation with his landlord, one Dr. Gozzi, who also happens to be a priest:
However, "nothingness" has been treated as a serious subject for a very long time. In philosophy, to avoid linguistic traps over the meaning of "nothing", a phrase such as not-being is often employed to make clear what is being discussed.
One of the earliest Western philosophers to consider nothing as a concept was Parmenides (5th century BC), who was a Greek philosopher of the monist school. He argued that "nothing" cannot exist by the following line of reasoning: To speak of a thing, one has to speak of a thing that exists. Since we can speak of a thing in the past, this thing must still exist (in some sense) now, and from this he concludes that there is no such thing as change. As a corollary, there can be no such things as coming-into-being, passing-out-of-being, or not-being.
Parmenides was taken seriously by other philosophers, influencing, for instance, Socrates and Plato. Aristotle gives Parmenides serious consideration but concludes, "Although these opinions seem to follow logically in a dialectical discussion, yet to believe them seems next door to madness when one considers the facts."
In modern times, Albert Einstein's concept of spacetime has led many scientists, including Einstein himself, to adopt a position remarkably similar to Parmenides. On the death of his friend Michele Besso, Einstein consoled his widow with the words, "Now he has departed from this strange world a little ahead of me. That signifies nothing. For those of us that believe in physics, the distinction between past, present and future is only a stubbornly persistent illusion." 
Leucippus (early 5th century BC), one of the atomists, along with other philosophers of his time, made attempts to reconcile this monism with the everyday observation of motion and change. He accepted the monist position that there could be no motion without a void. The void is the opposite of being. It is not-being. On the other hand, there exists something known as an absolute plenum, a space filled with matter, and there can be no motion in a plenum because it is completely full. But, there is not just one monolithic plenum, for existence consists of a multiplicity of plenums. These are the invisibly small "atoms" of Greek atomist theory, later expanded by Democritus (circa 460 BC – 370 BC), which allows the void to "exist" between them. In this scenario, macroscopic objects can come-into-being, move through space, and pass into not-being by means of the coming together and moving apart of their constituent atoms. The void must exist to allow this to happen, or else the "frozen world" of Parmenides must be accepted.
Bertrand Russell points out that this does not exactly defeat the argument of Parmenides but, rather, ignores it by taking the rather modern scientific position of starting with the observed data (motion, etc.) and constructing a theory based on the data, as opposed to Parmenides' attempts to work from pure logic. Russell also observes that both sides were mistaken in believing that there can be no motion in a plenum, but arguably motion cannot start in a plenum. Cyril Bailey notes that Leucippus is the first to say that a "thing" (the void) might be real without being a body and points out the irony that this comes from a materialistic atomist. Leucippus is therefore the first to say that "nothing" has a reality attached to it.
Aristotle, Newton, Descartes
Aristotle (384–322 BC) provided the classic escape from the logical problem posed by Parmenides by distinguishing things that are matter and things that are space. In this scenario, space is not "nothing" but, rather, a receptacle in which objects of matter can be placed. The true void (as "nothing") is different from "space" and is removed from consideration. This characterization of space reached its pinnacle with Isaac Newton who asserted the existence of absolute space. René Descartes, on the other hand, returned to a Parmenides-like argument of denying the existence of space. For Descartes, there was matter, and there was extension of matter leaving no room for the existence of "nothing".
The idea that space can actually be empty was generally still not accepted by philosophers who invoked arguments similar to the plenum reasoning. Although Descartes views on this were challenged by Blaise Pascal, he declined to overturn the traditional belief, horror vacui, commonly stated as "nature abhors a vacuum". This remained so until Evangelista Torricelli invented the barometer in 1643 and showed that an empty space appeared if the mercury tube was turned upside down. This phenomenon being known as the Torricelli vacuum and the unit of vacuum pressure, the torr, being named after him. Even Torricelli's teacher, the famous Galileo Galilei had previously been unable to adequately explain the sucking action of a pump.
John the Scot
John the Scot, or Johannes Scotus Eriugena (c. 815–877) held many surprisingly heretical beliefs for the time he lived in for which no action appears ever to have been taken against him. His ideas mostly stem from, or are based on his work of translating pseudo-Dionysius. His beliefs are essentially pantheist and he classifies evil, amongst many other things, into not-being. This is done on the grounds that evil is the opposite of good, a quality of God, but God can have no opposite, since God is everything in the pantheist view of the world. Similarly, the idea that God created the world out of "nothing" is to be interpreted as meaning that the "nothing" here is synonymous with God.
G. W. F. Hegel
Georg Wilhelm Friedrich Hegel (1770–1831) is the philosopher who brought the dialectical method to a new pinnacle of development. According to Hegel in Science of Logic, the dialectical methods consists of three steps. First, a thesis is given, which can be any proposition in logic. Second, the antithesis of the thesis is formed and, finally, a synthesis incorporating both thesis and antithesis. Hegel believed that no proposition taken by itself can be completely true. Only the whole can be true, and the dialectical synthesis was the means by which the whole could be examined in relation to a specific proposition. Truth consists of the whole process. Separating out thesis, antithesis, or synthesis as a stand-alone statement results in something that is in some way or other untrue. The concept of "nothing" arises in Hegel right at the beginning of his Logic. The whole is called by Hegel the "Absolute" and is to be viewed as something spiritual. Hegel then has:
The most prominent figure among the existentialists is Jean-Paul Sartre, whose ideas in his book Being and Nothingness (L'être et le néant) are heavily influenced by Being and Time (Sein und Zeit) of Martin Heidegger, although Heidegger later stated that he was misunderstood by Sartre. Sartre defines two kinds of "being" (être). One kind is être-en-soi, the brute existence of things such as a tree. The other kind is être-pour-soi which is consciousness. Sartre claims that this second kind of being is "nothing" since consciousness cannot be an object of consciousness and can possess no essence. Sartre, and even more so, Jaques Lacan, use this conception of nothing as the foundation of their atheist philosophy. Equating nothingness with being leads to creation from nothing and hence God is no longer needed for there to be existence.
The understanding of 'nothing' varies widely between cultures, especially between Western and Eastern cultures and philosophical traditions. For instance, Śūnyatā (emptiness), unlike "nothingness", is considered to be a state of mind in some forms of Buddhism (see Nirvana, mu, and Bodhi). Achieving 'nothing' as a state of mind in this tradition allows one to be totally focused on a thought or activity at a level of intensity that they would not be able to achieve if they were consciously thinking. A classic example of this is an archer attempting to erase the mind and clear the thoughts to better focus on the shot. Some authors have pointed to similarities between the Buddhist conception of nothingness and the ideas of Martin Heidegger and existentialists like Sartre, although this connection has not been explicitly made by the philosophers themselves.
The Kyoto School handles the concept of nothingness as well.
In computing, "nothing" can be a keyword (in VB.Net) used in place of something unassigned, a data abstraction. Although a computer's storage hardware always contains numbers, "nothing" symbolizes a number skipped by the system when the programmer desires. Many systems have similar capabilities but different keywords, such as "null" (e.g. SQL), "NUL", "nil", and "None" (Python).
To instruct a computer processor to do nothing, a keyword such as "NOP" may be available. This is a control abstraction; a processor that executes NOP will behave identically to a processor that does not process this directive.