Science

In mathematics, "nothing" does not have a technical meaning. The number zero is often used interchangeably with the term. It could also be said that a set contains "nothing" if and only if it is the empty set, in which case its cardinality (or size) is zero. In other words, the word "nothing" can be an informal term for an empty set.

In physics, the word nothing is not used in any technical sense either. A region of space is called a vacuum if it does not contain any matter, though it can contain physical fields. In fact, it is practically impossible to construct a region of space that contains no matter or fields, since gravity cannot be blocked and all objects at a non-zero temperature radiate electromagnetically. However, even if such a region existed, it could still not be referred to as "nothing", since it has properties and a measurable existence as part of the quantum-mechanical vacuum.

In computing, "nothing" (in VB.Net), or "null" (in Java, C#, and others), can be a keyword used to represent an unassigned variable, a pointer that does not point to any particular memory address, or a reference that does not refer to a specific object. Similarly, null is used in SQL as a symbolic representation of the absence of data. This meta-data usage of null is different from the unprintable ASCII and unicode null character, which has a numerical value of zero—although this is different from the ASCII character for zero ("0"). The ASCII blank character (" ") is not the same as an empty string (""), which is itself sometimes confused with the null pointer in languages such as C. Most forms of assembly language have a no-operation (NOP) instruction (often with a numerical value of zero)—that is, a command to do nothing, which can prove useful for blanking out areas of problem code.