Nothing comes from nothing


Nothing comes from nothing is a philosophical dictum first argued by Parmenides. It is associated with ancient Greek cosmology, such as is presented not just in the works of Homer and Hesiod, but also in virtually every internal system: there is no break in-between a world that did not exist and one that did, since it could not be created ex nihilo in the first place.

Parmenides

The idea that "nothing comes from nothing", as articulated by Parmenides, first appears in Aristotle's Physics:
The above, in a translation based on the John Burnet translation, appears as follows:

Lucretius

The Roman poet and philosopher Lucretius expressed this principle in his first book of De Rerum Natura
He then continues on discussing how matter is required to make matter and that objects cannot spring forth without reasonable cause.

Modern physics

The law of conservation of energy states that the total energy of an isolated system cannot change. The zero-energy universe states that the amount of energy in the universe minus the amount of gravity is exactly zero. That is the only kind of universe that could come from nothing, assuming such a zero-energy universe already is nothing. Such a universe would need to be flat, a state which does not contradict current observations that the universe is flat with a 0.5% margin of error.
Some physicists—such as Lawrence Krauss, Stephen Hawking, and Michio Kaku—define or defined 'nothing' as an unstable quantum vacuum that contains no particles. This is different from the philosophical conception of nothing, which has no inherent properties and is not governed by physical laws.
Quantum mechanics proposes that pairs of virtual particles are being created from quantum fluctuations in this "empty" space all the time. If these pairs do not mutually annihilate right away, they could be detected as real particles, for example if one falls into a black hole and its opposite is emitted as Hawking radiation.
Alexander Vilenkin defines "nothing" as a universe of zero size: It is closer to nothing as one can get, but still not nothing.